of Each Workshop Paper - Princeton

Ill.

Summary and Discussionof Each Workshop Paper

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Summary and Discussionof Each Workshop Paper— — —

TOBACCO LEAF PROTEIN

The concept of using leaf protein as a foodis not new. Over the last 60 years, scientistsfrom several countries have researched the ex-tractability of proteins from leaves and prepa-ration of leaf protein concentrate (LPC). Thegreatest impetus for leaf protein research camein the early 1940’s when Norman Pirie of Eng-land examined the potential of producing LPCas a source of protein for human consumptionto alleviate wartime food shortages. AfterWorld War II the interest in leaf proteins forhuman use waned because their green colorand slightly grassy taste hindered consumer ac-ceptance of them as human foods. Since thattime, the Pirie process for leaf protein extrac-tion has been modified for commercial produc-tion of LPC for livestock feed. Recently, a newtechnique has been developed and tested at thepilot-plant stage that can extract a high-quality,purified protein from immature tobacco plants.It has been proposed that tobacco be used asa dual- or multi-product crop for proteins andsmoking and chewing tobacco,

The extraction process yields six products.They are:

Crystalline Fraction 1 Protein

Fraction 1 protein is a water-soluble, taste-less, and odorless white powder. It is nutri-tious; when fed to rats, crystalline Fraction 1protein exhibited a higher protein efficiencyratio (PER) than casein, the common standardfor comparing the nutritional quality of pro-teins. Because it is tasteless and odorless, Frac-tion 1 protein can be added to foods to improvetheir protein content and quality withoutchanging their taste or smell. This product canbe added to foods for its albumin-like func-tional properties such as heat set and gelling.It has been suggested that if crystalline Frac-

tion 1 is washed free of sodium and potassium,it might be useful for kidney patients as asource of high-quality protein, although this hasnot been substantiated by research.

Fraction 2 Protein

This product also is water-soluble and nutri-tious and might be used as a protein supple-ment for food products such as cereals. Itsfunctional properties are not so desirable asthose of Fraction 1 protein, however.

Green Sludge

Green sludge consists of water-insoluble pro-teins and starch. It possibly could be marketedas a feed for poultry and other nonruminantanimals. Green sludge can be converted by sol-vent extraction to a material similar to soybeanmeal in properties and amino acid com-position.

Green Residue

This product represents the fibrous materialleft after protein extraction. The solids are com-posed of more than 50 percent cellulose andhemicellulose and about 13 percent protein. Itis similar to alfalfa hay in nutritional value, Thegreen residue can be converted through organ-ic solvent extraction to white fibers suitable forcigarette manufacturing. The resultant depro-teinized cigarettes would be lower in tar andnicotine than commercial cigarettes today.

Pigments and OtherBio-Organic Compounds

Organic solvent extraction of the green res-idue and green sludge produces pigments andother organic compounds. Carotenoids can be

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16 ● Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

separated out and possibly marketed as poultryfeed supplements.

Low-MoIecular Weight Compounds

This product, composed of water-solublesugars, amino acids, vitamins, salts, and othercompounds, might be used as a fermentationliquor after it is concentrated by evaporation.

The extraction procedure for tobacco proteinis fairly simple. First, the aboveground portionsof the tobacco plants are crushed. The liq-uid is pressed out, leaving behind the solids(green residue). The green juice is heated rapid-ly to 1250 F (520 C) then quickly cooled to roomtemperature, causing green particulate matter(green sludge) to settle out of the now brownliquid. The brown juice is pumped to a storagetank where within 6 to 10 hours Fraction 1 pro-tein crystallizes out of solution. The crystalsare collected and washed. The remaining liquidis acidified, causing Fraction 2 proteins toprecipitate out of solution. They, too, are col-lected and washed.

The process has the following advantages:providing a high-quality protein from a plantalready grown on a total of 2.5 million hectaresover a wide geographical range, and providinga smoking product that is lower in the constit-uents believed to be health hazards. Althoughthe results of pilot-scale research seem prom-ising, several technical, economic, social, andenvironmental problems would have to besolved before tobacco protein extraction couldbe viable on a commercial scale.

This procedure was developed by Leaf Pro-tein, Inc. (LPI), a small venture capital corpora-tion. To investigate the potential of this proc-ess on a commercial scale, LPI formed a jointventure with the North Carolina Farm BureauFederation. The Federation, together with Gen-eral Foods Corp., helped finance a pilot plantin the tobacco growing region of North Caro-lina, a small plant able to process about a tonof fresh plants every 9 to 10 hours. The plantwas operated first in August 1980. Each experi-ment required a minimum of 600 lbs of freshplants. Climatic and technical problems were

encountered, and it was not until July 1982 thatthe pilot plant was consistently able to produceFraction 1 protein of high purity. Although thepilot-scale operations appeared promising, atthe end of the tobacco growing season the re-search facility was closed and the equipmentwas sent to the University of Florida which isusing it experimentally to produce pig feed.The research was discontinued because of lackof industry interest in investing in commercialscale-up of the LPI process. This lack of interestwas not caused by predicted scaling-up prob-lems but by fears that the products would havelimited marketability because of the socialstigma attached to tobacco and the changedcharacter of cigarettes and chewing tobaccowould not gain consumer acceptance. The riskinvolved in investment was perceived to be toohigh.

Consumer attitude is perhaps the most seri-ous deterrent to using tobacco as a source forprotein. Given tobacco’s negative image in theeyes of many American consumers, the appealfor foods containing tobacco leaf protein couldbe questionable. Tobacco protein would haveto compete with the already abundant sourcesof protein in the United States—ranging fromvegetable oilseed proteins to animal pro-teins—which are well-established and probablymore readily acceptable to the public. Thepotential retail value of the extracted proteinalone would not economically justify growingtobacco since all three proteins together ac-count for only about 20 percent of the totalestimated value of the finished products fromtobacco. As much as 55 percent of the crop’sestimated value would come from sale of thefibrous portion for cigarette manufacture.Unless the deproteinized fiber is acceptable tomanufacturers and consumers, the processwould not be profitable. No commercial firmhas been willing to invest in commercial scal-ing-up of the LPI system. Whether the changedcharacter of a cigarette would appeal to con-sumer taste is in question but will be a majorfactor in the economic success of tobacco pro-tein extraction.

There are many technical constraints facingthe LPI process, both at the agronomic and the

Ill.—Summary and Discussion of Each Workshop Paper ● 17

processing level. The time at which the tobac-co is harvested is critical because the leaf pro-tein is surprisingly variable on a daily basis.Because the proteins and other leaf constitu-ents deteriorate rapidly after harvesting, theharvested material must be processed almostimmediately. At the processing level, the leafpulp is difficult to work with when using con-ventional conveying machinery because it isviscous and is corrosive to metal. Anotherproblem which is not so apparent at the pilotlevel as on the commercial level is disposal ofwastes. Since about 90 percent of the plant ma-terial is water, handling and disposal of largeamounts of fluid must be arranged. The brownjuice left after extraction of the proteins andfiber has a high biological oxygen demand(BOD) so would be a source of pollution if re-leased unaltered into an aquatic system. Evap-oration processes to condense the liquids, how-ever, are expensive. Solvent recovery is anotherproblem. Because they are expensive, a certainproportion of the solvents used in processinggreen residue and green sludge must be recov-ered. This may be a problem encountered withcommercial scale-up.

The environmental impacts of tobacco as acrop should be examined. Tobacco needs largeinputs of energy, biocides (insecticides, herbi-cides, fungicides, nematicides), and fertilizersfor cultivation. When grown in the conven-tional manner, tobacco is “hard on the soil. ”It readily extracts soil nutrients, particularlynitrogen, so unless large amounts of fertilizerare applied to tobacco fields, the crops overtime will tend to decrease soil fertility. Whengrown for protein extraction, tobacco plantscould be harvested four times per growing sea-son. This faster rotation probably would leadto even faster nutrient depletion and would re-quire greater fertilizer inputs than even con-ventional tobacco crops. Cultivation of tobac-co, an annual planted at relatively wide spac-ing, presents an erosion hazard. The denserspacing used for protein tobacco comparedwith conventional tobacco might help reduceerosion rates. However, more frequent har-vests, repeatedly exposing the soil to wind andrainfall, probably would increase erosion.

Conventional tobacco production requireslarge inputs of biocides. Pesticide inputs maydecrease because the “cosmetic” appearancerequired of the cigarette tobacco leaf is notnecessary for protein extraction. Seedlingseither would be raised in seedbeds that havebeen fumigated to kill micro-organisms andthen transplanted in the field or would beraised directly in newly cleared land. The lat-ter obviously is not desirable or possible inmany places. The need for herbicide applica-tion would be greater if tobacco were grownfor protein extraction because repeated har-vests provide increased opportunity for weedencroachment. It seems that growing tobaccofor protein extraction would be equally, if notmore, ecologically disruptive than conven-tional tobacco, a crop widely recognized as aresource-demanding crop.

A great deal more economic information isneeded to assess the commercial viability of theprocess. No processing costs at the pilot levelor projected commercial processing costs areavailable. In addition, the ability of the prod-ucts to enter the marketplace must be assessed.The products would have to be able to com-pete on the market with alternative productsin price, availability, ease of use, and consumertaste preference (with products for human con-sumption). For example, Fraction 1 proteinwould have to compete with egg albumin asa functional food additive and the bio-organiccompounds from the green residence andgreen sludge with alfalfa as a source of carot-enoids for poultry feed. Both egg-whites andalfalfa are well-established in these markets andtobacco might have difficulty attracting a por-tion of these markets away from them. Mostimportant, the deproteinized tobacco fiberswould have to be able to compete with mature,cured tobacco leaves. Not only would a dif-ferent taste have to be acceptable to the con-sumer, but the processor would have to be will-ing to make processing changes for the newproduct, An important factor in market en-trance is the amount of product available. Ifonly limited quantities of a product in a large-volume market (e.g., fibers for tobacco or forlivestock feed) are available, industry may be


unwilling to go to the trouble and expense ofusing small and/or intermittent amounts of theproducts.

Although the LPI process appears promisingat the pilot-level scale, a great number oftechnical, ecological, social, and economic bar-riers stand in the way of commercial feasibili-ty. The cost of taking this process from the pi-lot-plant scale to commerical production scalecould be high. Although the pilot-plant opera-tion was supported by private capital, the pri-vate sector is showing reluctance to work witha tobacco-related product. Despite potential ad-vantages of the products, financial backing forfurther research on agronomic, extraction,and product testing and marketing has notbeen forthcoming. It seems that tobacco proc-essors are not interested in altering an alreadyprofitable manufacturing system to incorporateprocessing of tobacco proteins of uncertain

marketability, and that the food industry is un-willing to invest in a crop carrying such a so-cial stigma. In addition, tobacco proteins havenot undergone mandatory Food and Drug Ad-ministration (FDA) testing on animals to assesstheir safety for human consumption. Until thishappens food processors may be leery of thepossible presence of toxic compounds in theproteins.

There is some evidence that the protein ex-traction process might be used successfully onsoybeans, clover, alfalfa, tomato, spinach, andother crops which are less ecologically disrup-tive and more socially acceptable. These plantswould face many of the same problems withresearch and commercial scale-up that tobac-co faces, but could be more acceptable to pro-ducers and consumers. Perhaps further re-search should investigate these alternativecrops for LPI processing.

PROTEIN FROM TROPICAL PLANTS

At the present growth rate, world populationwill double within the next 30 to 40 years. Thispopulation increase will be most rapid in theless developed countries of the humid lowlandTropics, where annual increase in food produc-tion remains low. LPC extracted from tropicalplants is being investigated as a possible sourceof protein. LPC is prepared from alfalfa on alarge commercial scale in Europe and theUnited States. Because alfalfa has not beengrown successfully in the humid Tropics, suit-able tropical replacements are needed for leafprotein extraction.

Leaf protein fractionation is based on theprinciple that nitrogen-fixing plants containhigher levels of protein than can be used byruminant animals and that nonruminants, ableto assimilate only a portion of total plant pro-tein, cannot consume the volume of leaves nec-essary to meet their protein needs. The highprotein content of these plants allows for par-tial removal of protein for nonruminant useand subsequent use of the remainder of theplant by ruminants.

USDA’s Tropical Agriculture Research Sta-tion in Mayaguez, Puerto Rico, has tested atleast 500 introductions of tropical plants as pos-sible sources of LPC. Desirable characteristicsof plants as sources of leaf protein concentrateinclude high protein content, high dry-mattercontent, readily extractable protein from fresh-ly cut plants, good regrowth potential, abilityto fix nitrogen, erect growth for easy mechan-ical harvesting, nontoxicity, and low concen-tration of antinutritional substances.

The extraction procedure used was a rela-tively simple process in which the liquidpressed out of the leaves was subjected to suc-cessively higher temperatures, thus causing theproteins to precipitate out of solution. At 55°C, a green coagulum formed and was separatedby centrifugation, washed several times, andspread in thin layers on glass plates to dry. Thesupernatant from the centrifugation washeated carefully to 640° C. The white curd coag-ulum that formed was separated by centrifuga-tion, washed with acetone, and dried in a ro-tary evaporator. The liquid was heated further


to 820 C. After cooling, a light tan precipitateformed and was processed in the same way asthe 64° C fraction.

The spontaneous coagulation of protein inthe juice extracted from some plants (subse-quently called Type I plants), including cassava(Manihot esculenta), leucaena (Leucaenaleucocephala), and many other tree legumes,was observed during the survey of tropicalplants. Another group of plants (Type II)yielded a green protein coagulum after the ex-tracted green plant juice was heated to 55° Cand yielded a very small quantity of a light tanprecipitate at 820 C. This first was observedwith leaf protein extract of sorghum-sudangrass hybrids and other grasses. Careful heatfractionation of aqueous leaf extracts of otherplants (Type III) yielded three distinct proteinfractions: a greencoagulumat550 C, a copiouswhite protein precipitate at640 C, and a smallamount of light tan precipitate at 820 C. Theseare the most promising plants for leaf proteinextraction; species selected for further studywere chosen from this group. A final group(Type IV) includes plants in which the proteinsin the aqueous extracts do not precipitate eitherspontaneously or after heat treatment.

Leaf protein concentrates subsequently wereprepared from seven Type III plants (Vignaunguiculata, Clitoria ternatea, Desmodium dis-tortum, Psophocarpus tetragonolobus, Macrop-tilium lathyroides, Phaseolus calcaratus, Bras-sica napus) and leucaena and cassava, bothType I plants. The protein quality of the LPCextracted from these plants was evaluatedusing rats. The tropical legumes cowpea (Vig-na unguiculate), Desmodium distortum, ricebean (Phaseolus calcaratus), and winged bean(Psophocarpus tetragonolobus) gave excellentresults, comparable to those obtainable fromalfalfa LPC. The LPC from these plants hadamino acid contents similar to each other andto reported values for alfalfa LPC and soybeanmeal. The tests supported the suspicion thatthe spontaneously precipitated protein concen-trate from Type I plants would have less nutri-tional value; rats fed LPC from cassava and leu-caena grew poorly. USDA investigations indi-cated that with current methods, good quality

leaf protein concentrates for nonruminantscould not be prepared from many of the legu-minous tree leaves because the presence ofphenolic substances negatively affects thenutritional value of the extracted proteins. Theleaves of some of these species, however, couldbe used as feed for ruminants.

Investigations of tropical grasses as sourcesfor leaf protein extraction showed them to below in extractable protein. Nitrogen fertilizercould be applied to fields to increase the pro-tein content in grasses, but the increased valueprobably would not offset the cost of the fer-tilizer. Tropical grasses were considered poorsources of LPC because they have higher pro-duction and processing costs and lower quali-ty and quantity of extractionable proteins.

The following conclusions were drawn fromthis relatively short investigation of possibletropical plant sources for leaf protein extrac-tion:

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Some tropical plants are sources of LPCthat are equivalent to alfalfa LPC in yield,extractability, and nutritional quality.A single crop in the Tropics cannot beused for year-round production; a patternof different plants has to be formulated forrainy and dry seasons.Cassava, leucaena, other tropical trees,and tropical grasses seem to be unpromis-ing as potential sources of LPC.The type and number of protein fractionsobtained by heat fractionation can be usedas a rapid preliminary method to screenplants for protein extraction potential.

Machinery has been developed in Englandand the United States for LPC processing.Some are used for large-scale commercial LPCoperations in Europe and the United States,and others have been used to assess its viabili-ty for on-farm and village-level LPC produc-tion. Research on village-level LPC productionhas been carried out in India, Pakistan, and SriLanka. Work in Aurangabad, India, is the mostrelevant to practical application of the LPC pro-duction systems on the village level. Establish-ment of a commercially viable, locally operatedLPC production unit at a village farm was at-

20 . Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

tempted. The green protein concentrate fromalfalfa was used as a milk replacement forcalves (thus making the cow milk available forhuman consumption), as poultry feed, and ashuman food. The pressed crop was fed imme-diately to cows. The cost of equipment and adairy unit of five to six cows was assessed at$4,450, which is prohibitively expensive for asmall-farm operator but probably affordable forvillage cooperatives. Concurrent research inIndia on LPC production concluded that on anutritional basis, leaf protein would be muchless expensive than most protein from grainlegumes consumed in the area and that a LPC-containing product made for human consump-tion could provide half the daily protein re-quirements of a child at a price affordable tothe majority of Indian poor ($0.025 to $0.03 perday).

On-farm leaf protein fractionation has beenresearched in Britain, Australia, and the UnitedStates. The on-farm system is that after harvest-ing, the crop is processed to produce pressedforage for ruminants and a juice with solubleproteins for nonruminants. Processing takesplace on a farm and at least one of the productsis used at the production site. The ideal situa-tion would be a combined dairy and hog farmwhere the crop is grown and extraction prod-ucts used onsite, thus reducing transportationexpenses, storage costs, and spoilage. Researchat the University of Wisconsin at Madison hasconcentrated on development of a weather-in-dependent, on-farm forage-harvesting systemusing a protein fractionation process. Afterharvesting, the main produce is pressed foragethat can be preserved directly as silage. Fieldlosses from harvesting and baling are reducedand a higher percentage of the protein contentcan be retained in pressed residue than in sun-dried hays. Research results indicate that ru-minants respond to being fed pressed residueas they do nonfractionated plants. The juice ex-tracted from the plant material could be feddirectly to hogs to minimize storage and preser-vation expenses. The proteins in the juicedegrade rapidly and the carbohydrates fermentwithin a day, so the processing must be gearedto the feeding time of the animals. Proteins

could be isolated from the juice by fermenta-tion, but the product is not acceptable yet tohogs.

Commercial LPC production was initiated in1967 at the USDA Western Regional ResearchCenter in Berkeley, Calif. A highly mechanizedprocess, the Pro-Xan process, was developedfor obtaining LPC from alfalfa. The first com-mercial application of this process took placein France in association with a commercial al-falfa dehydrators plant. (Dehydration is carriedout immediately after harvesting to avoid lossesfrom haymaking and ensiling and to producea product higher in protein content than hayor silage.) Leaf protein concentrate from alfal-fa now is prepared on a large commercial scalein Europe and the United States for livestockfeed. There are plans to open a plant in NewZealand, and two pilot plants have been set upin Japan.

Attempts to process LPC to obtain an accept-able good-grade product have been unsuccess-ful. Green LPC from the 550 C fraction can beproduced economically, but its green color,grassy flavor, and low volubility have pre-vented acceptance by consumers and food pro-ducers. Purifying this protein concentrate bysolvent extraction is technically feasible butcostly and only partially effective. The whiteprotein fractions separated at 64° and 820 Care nutritious but are practically insoluble. Ifsoluble, they would be of greater use to the foodindustry. Producing a water-soluble, bland-tasting white protein using various filtrationtechniques including diafiltration, ultrafiltra-tion, and gel filtration has been attempted.Although gel filtration seems to be the most ef-fective system, it is very expensive. Anothermethod has been developed that produces apure, water-soluble protein at a lower pricethan gel filtration. This is a crystallization proc-ess used to extract Fraction 1 protein fromtobacco. * Although this process seems to betechnically feasible at the pilot-plant level, itseconomic feasibility has not been proven andhas encountered constraints to commercialscale-up.

*See paper by Wildman in the appendix.


Use of LPC technology in developing coun-tries is most promising as applied to medium-sized production systems such as cooperatives,organized communities, and large farms. On-farm production of LPC is too expensive andlabor-intensive to be feasible for most farmerswho own or lease small plots of agriculturalland. The system is probably most adaptableto cooperative farming operations, such as acombined dairy-hog operation. Onsite use ofthe products offers many advantages includinglower transportation and storage costs, reduc-ed waste because leaf production can be coor-dinated with demand for LPC and pressed fod-der, and ability to use excess pressed juice forirrigation water.

Large-scale LPC production might be possi-ble in developing countries if incorporated intoan integrated production system, such as anoperation combining dairy or beef cattle withhogs or poultry. The high degree of coordina-tion and planning of such an enterprise prob-

ably would restrict it to public ownership orto capital- and management-intensive privatefirms, such as beef exporters. While this wouldbenefit foreign exchange earnings, it would failto provide an inexpensive, efficient proteinsource for those in developing countries whoneed it most.

Screening of tropical plants for extractableprotein has produced several good candidatesfor LPC production in tropical and subtropicalcountries. Processing machinery has been de-veloped for alfalfa LPC production, but it mightbe adapted for use on tropical plants to meetdeveloping country needs. Before LPC produc-tion using tropical plants is feasible, however,comprehensive studies should be conducted onagronomic of plants chosen for protein extrac-tion, economic feasibility, farmers’ acceptanceof LPC extraction and use, and productiontechnologies. A variety of agricultural, econom-ic, and social factors and impacts must also beconsidered.

ENDOD IN COMBATING SCHISTOSOMIASIS

Rural people in Ethiopia and certain othercountries traditionally have washed theirclothes with a detergent solution made fromdried and ground ended berries. Ended (Phy-tolacca dodecandra), the soapberry plant, is ashrub that is closely related to the Americanpokeweed plant. In 1964, researchers studyingthe distribution of disease-carrying snails instreams found large numbers of dead snails im-mediately downstream from people washingclothes using ended as a detergent. Subsequentphytochemical studies indicated that endedcontains effective biocidal compounds. Endedis being studied as a potential molluscicide foruse against snails that carry schistosomiasis.

Schistosomiasis is a debilitating snail-bornedisease common throughout the Tropics andsubtropics. It is one of the most serious andrapidly spreading parasitic diseases of human-kind, affecting an estimated 200 million to 300million people and potentially infecting an ad-ditional 400 million. The disease is spread

when uninfected people work and bathe in thesame water as infected people. New shallow-water habitats for snails, the intermediatehosts, have been created by irrigation, hydro-electric power, and other water-related proj-ects, many of which have been funded by in-ternational agencies.

No single method to control schistosomiasiseffectively has been found. Ideally the most ef-fective treatment for the disease is site-specificand repeated molluscicide applications com-bined with mass treatment of all infected peo-ple, improved environmental sanitation, andhealth education. However, no safe, effective,and affordable drug suitable for mass treatmenthas been found, and available molluscicides areinadequate or expensive. Environmental san-itation and health education are long-rangemeasures. For now the most practical and ef-fective method to control schistosomiasis isthrough a combination of selective treatmentof infected individuals and control of new

22 ● Plants: The potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

transmission by killing the host snails at eachproven site of infection.

Although several chemical molluscicideshave been used within the last few decades tocontrol schistosomiasis and other snail-bornediseases (e.g., copper sulphate, Frescon, sodi-um pentachlorophenate, Yurimin), several ofthem are no longer produced either becausethey are ineffective or cannot be marketed. Theonly molluscicide recommended by the WorldHealth Organization is Bayluscide, an expen-sive chemical used only in a few developingcountries with the help of external financialassistance. The lack of a market as a result ofdeveloping countries’ limited foreign exchangehas discouraged the private sector from devel-oping other molluscicides. The discovery of en-dod and the lack of adequate and affordablechemical molluscicides have stimulated thetesting of plants as potential molluscicides.Croton (Croton tiglium, C. macrostachys), am-brosia (Ambrosia maratima), and jatrophaJatropha curcas) show some promising mol-luscicidal activity, but a great deal more workmust be done to evaluate their potential as com-mercial molluscicides. As recognized by aworkshop on plant molluscicides convened bythe United Nations Development Programme,World Bank, and World Health Organizationin January 1983, ended seems to be the mostpromising plant molluscicide evaluated to date.whereas several other chemical molluscicidesare unstable in intense sunlight or under dif-ferent water pHs and concentrations of organicor inorganic matter in the water, ended re-mains stable in sunlight and under a widerange of water conditions. It is a potent mol-luscicide, killing snails within hours. Testsshowed ended to have no mutagenic proper-ties, indicating that widespread use of it as amolluscicide might not pose a safety hazard tohumans.

A 5-year pilot study investigating the effectof ended on schistosomiasis was carried outin northern Ethiopia between 1969 and 1974.Systematic application of locally collected en-dod berries over the 5 years reduced the prev-alence of schistosomiasis in children aged 1 to6 from 50 to 7 percent, and in the entire popula-

tion (17,000) from 63 to 34 percent. The inci-dence of disease in an untreated nearby villagewas almost constant over the course of thestudy, indicating that the reduction in thetreated village was as a result of ended applica-tions. The cost of the treatment amounted toonly US $0.10 per person per year. A criticalelement in the success of this control study waslocal political support and community partic-ipation. The local political officials and munic-ipal council were involved in the planning andexecution of the study, and the council pro-vided finances, manpower, and facilities.

In addition to its value as a molluscicide, theended berry may have commercial potential asa detergent; an insecticide for the control ofmosquitoes, the black fly that carries riverblindness, and other water-breeding insects; afungicide against certain human skin diseases;a spermaticide or an abortifacient. Ended ber-ries have been used in Ethiopia and many othertropical countries for centuries to control anaquatic leach that is a major pest of livestock.The berries are also effective against snails thatspread fascioliasis, a serious cattle and sheepdisease.

Most chemical studies done on ended to datehave focused on saponins, the biocidal com-pounds in the berries. Saponins account foronly 25 percent of the dry weight of ended ber-ries, and the berries in turn represent only asmall proportion of the total plant biomass. Theberries, leaves, stems, and roots could be poten-tial sources of other useful products includingpectins, thickening agents, starches, sugars, an-imal feed, and fuels. As research on endedprogresses, these and other uses for the byprod-ucts might be developed. Ended is a potentialmultipurpose crop that could provide productsfor local use or support local industries.

The active chemical in ended berries hasbeen isolated, identified, and named Lem-matoxin. Three extraction procedures havebeen developed, two of which are based on sol-vent extraction and the third on fermentation.The fermentation method is simple; berries areground, soaked in water, and left in a warmplace to ferment by means of the yeast cells

III.—Summary and Discussion of Each Workshop Paper . 23

normally found on ended berries. This is per-haps the most practical extraction method fordeveloping countries to use. Processing equip-ment is affordable, it can be supplied andoperated locally, and no extraction solventshave to be imported. The fermentation extractcan be applied in a variety of ways. It can bedusted on the surface of the water as a powder,sprayed on the water as an emulsion, or com-pressed into briquettes to allow for slow releaseof the active chemical.

If high-potency ended varieties could begrown locally, the dried and ground berriescould be applied directly to rivers, streams, andirrigation channels. This would avoid the proc-essing costs involved in preparing an extract.A study carried out between 1976 and 1981tested 65 different strains of ended and chosethree on the basis of molluscicidal potency,berry yields, and resistance to insect pests anddrought. These three strains subsequently wereused in cloning experiments using tissue cul-ture. Plantlets developed through mass propa-gation have been distributed to Brazil and threeAfrican countries for field trials. Additionalresearch is using tissue-culturing for in vitrobiosynthesis of the active molluscicidal prin-ciple.

Although research on chemistry, extractionapplication, and toxicity of ended has pro-gressed rapidly since 1964, a great deal moretoxicological, agronomic, and economic re-search is necessary before large-scale applica-tion of ended for control of schistosomiasis andother snail-borne diseases could be possible.Toxicity studies on sheep and dogs showedthat while intravenous injection of ended canbe fatal, oral intake of small to moderateamounts can be tolerated by animals and largeamounts induce vomiting. This emetic proper-ty acts to protect people and animals from pos-sible overdoses. Ended berries, leaves, androots have been taken orally for centuries inseveral African countries for various medicalpurposes, including birth control and riddingthe body of internal parasites. Had endedshown negative effects, it probably would havebeen discarded long ago. Mutagenic tests onended berries carried out in vitro have been

negative. However, more comprehensive mu-tagenic and toxicity tests should be carried outon a variety of different animal species to pro-vide more complete evidence of ended’s safety.

Because ended has never been grown com-mercially on a large scale, it will have to be sub-jected to a range of agronomic studies. Agro-nomic research on ended during the last dec-ade has concentrated on selection and breedingof plants for good growth and berry produc-tivity and potency. Some studies have recent-ly been carried out in Ethiopia on its plant ecol-ogy and susceptibility to pests, particularly toa stem-boring fly that kills young shoots. Datahave also been collected on plant nutrition, ger-mination, spacing, and irrigation. This prelimi-nary work will have to be expanded; field trialsare needed to determine both the agronomicneeds of ended and the ecological effects ofcultivating the plant, including impacts on soil,water availability, and pest outbreaks.

Although no comprehensive ecological stud-ies to determine the effects of ended applica-tion on streams have been conducted, obser-vations indicate that local animal populationsare largely unaffected. Any localized effects ofended application are unlikely to be long-last-ing because the active chemical biodegradesrapidly. Within 24 to 48 hours ended’s poten-cy declines. Extensive research is needed toprovide comprehensive data on ecological im-pacts.

In summary, ended appears to be a promis-ing potential as a molluscicide for controllingschistosomiasis. Research on endod, however,is still at an early stage. Before ended can beused as a molluscicide, far more research isneeded on its toxicity, agronomy, ecology, eco-nomics, extraction, and application techniques,cost effectiveness compared to other mollus-cicides, and the distribution and marketing ofberries or the extracted molluscicide. In addi-tion, its potential as a multiproduct crop shouldbe examined.

Ended could be a community-controlled sol-ution in developing countries to the wide-spread problem of schistosomiasis. Because theplant can be grown locally and the biocidal

24 . P/ants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

compound extracted simply using a low-tech-nology fermentation method, inexpensive localproduction of the molluscicide is possible. Thealternative of importing expensive Bayluscideor another chemical molluscicide is not a viableoption for most developing countries with lim-ited foreign exchange. Ended could be culti-vated and extracted either publicly or private-ly and then applied to infection sites by thecommunity. The public sector would have tobear the startup research costs for such acommunity-based public health project, but fi-nancial assistance might be sought from devel-opment assistance agencies such as the U.S.Agency for International Development. Once

started, a project could be sustained by localrevenues and paid or volunteer communitylabor.

Ended use need not be restricted to schisto-somiasis control in developing countries. Fur-ther research may develop endod’s potentialas a source of larvicides, insecticides, sperma-tocides, or other products. A similar commu-nity-based project based on the use of endedas a larvicide for the control of malaria perhapsis another future application. Ended might alsobe investigated as a biocide for pest control inthe United States.

MILKWEED: A POTENTIAL NEW CROPFOR THE WESTERN UNITED STATES

Arid/semiarid-land plants in the UnitedStates represent relatively untapped sources ofvaluable oils, waxes, natural rubbers, insec-ticides, medicines, and important chemicalfeedstocks. These chemicals, produced byplants as defenses against predators, pests, andclimatic stresses such as temperature extremesand drought, could be extracted to provide avariety of commercial products. Interest inarid/semiarid-land plants as sources of insectrepellents, attractants, and toxicants; * fossilfuel substitutes; and chemical feedstocks** isgrowing. The showy milkweed (Asclepiasspeciosa), discussed in greater detail later, isan example of an arid/semiarid-land plantbeing investigated as a potential multipurposecrop for chemical feedstocks and fiber prod-ucts. Arid and semiarid lands, often consideredagriculturally unproductive in relation to tradi-tional U.S. food and fiber crops, could becomeimportant for the production of a variety ofcommercial chemical extracts.

Despite the general lack of attention to thecommercial potential of arid/semiarid-landplants, some of these plants already provide avariety of commercial products. Some arid/

*See paper by Jacobson in the appendix.**See paper by Tankersley and Wheaton in the appendix.

semiarid-land-plant extracts used in the UnitedStates are jojoba oil, gum arabic, tragacanthgum, candelilla wax, and natural rubber fromguayule. Jojoba oil is a valuable lubricant ableto withstand high temperatures. The first com-mercial harvest of cultivated jojoba plants inthe Southwest United States occurred in 1982;until then only wild plants had been harvested.The market value of imports of gum arabic,used in the food industry for its functionalproperties, was about $8 million in 1982. Gumarabic is obtained from an Acacia speciesnative to Africa and the Middle East, but a re-lated species could be grown in the UnitedStates to supply an equivalent gum and providesavings in foreign exchange. Tragacanth gumis used in pharmaceuticals and cosmetics andas a thickening agent in some prepared foods.Although the plant could be grown in theUnited States, gum is imported from Iran. Asa result of political instability in the area, im-ports recently have been erratic. The UnitedStates has had similar problems with procur-ing candelilla wax which is imported fromMexico. Imports dropped by over 50 percentbetween 1978 and 1982 as a result of harvest-ing problems. Guayule, a desert shrub that con-tains natural rubber, could be grown in theUnited States to provide a substitute for Hevea


rubber imported from Southeast Asia. DuringWorld War II when the supply of imported rub-ber was cut off, guayule was produced in theSouthwestern United States as an alternativesource of natural rubber. Production was dis-continued after the war when synthetic rub-ber became available and importation of natur-al rubber resumed. Interest in domestic pro-duction of guayule has again arisen with in-creasing demand for rubber and higher pricesfor hydrocarbons and petroleum-based indus-trial feedstocks. Semicommercial productionis being carried out in the Southwest UnitedStates. *

A major constraint to developing new arid/semiarid-land plants and plant products is lackof adequate field-screening procedures. Theavailability of good field-screening technologiescould help identify promising species for re-search and locate good sources of germ plasm(e.g., for high oil content, high biomass produc-tivity) for potential and existing crops. Chem-ical screening generally has been done in thelaboratory by solvent extraction. Fairly recent-ly, two laboratory techniques, wide-line nucle-ar magnetic resonance (NMR) and near-infra-red reflectance (NIR), have been developed formore rapid screening, All three methods re-quire that plants be brought in from the fieldfor laboratory analysis. Solvent extraction mustbe done in the laboratory; NMR is not portableenough for field screening; and even thoughportable NIR units are available, plant materialstill has to be brought to the lab. Collecting,preparing, and documenting field samples aretime-consuming activities, and because mostof the material will be unpromising and there-fore discarded, they are not cost effective. Theplants yielding good laboratory results have tobe relocated in the field, a task that is often dif-ficult. It would be far more time- and cost-effi-cient if plants could be screened rapidly in thefield and seeds or cuttings from the promisingplants collected then. Lack of adequate field-screening techniques poses a serious deterrent

*See OTA background paper entitled Water-Related Tech-nologies for Sustainable Agriculture in Arid/Semiarid Lands:Selected Foreign Experience, ch. V, for more information onguayule.

to the search for potential new crops and plantproducts.

A plant should be screened for a range ofchemical compounds to investigate its poten-tial as a multiproduct crop. Once the plant ma-terial has been collected and transported to theprocessing site, additional costs for extractingmore than one product may be relatively smallbut can add significantly to the total commer-cial value of the plant. Multiple-product devel-opment can justify the costs of growing, har-vesting, and transporting the crop and extract-ing the chemicals. In addition, the developmentof many products helps buffer the market riskof the crop; if one product fails, the other prod-ucts can help offset the economic loss,

Different techniques are used to extract par-ticular chemicals. In general, polar solvents ex-tract biologically active compounds and otherreactive chemicals, including dyes, antioxi-dants, and adhesives. Nonpolar solvents yieldcompounds that are useful as lubricants,waxes, and elastomers. The water or acidicaqueous fraction may provide polysaccharidessuch as gum or pectin and some water-solubleprotein. The residue from extraction is com-prised of cellulose, hemicellulose, protein, andlignin (if present). This material maybe burnedas fuel, used as livestock feed, fermented to pro-duce industrial chemicals, or the fiber mayberemoved and used for pulp, paper, or fabric.

Native Plants, Inc. (NPI) has been studyingthe showy milkweed (Asclepias speciosa) aspart of a program to investigate plants as newsources of commercial chemicals. This specieswas chosen for study because it is distributedover a wide range of climates and soil types.It is an herbaceous perennial found throughoutthe Western United States, from the Mississip-pi River to the Pacific Ocean, and from cen-tral Alberta and Saskatchewan to central Okla-homa. Milkweed is a potential crop for areasof low rainfall. For example, A. speciosa canbe grown easily in the western Great Plains,where overuse of the ground water stored inthe Ogallala aquifer is requiring a shift fromirrigated to dryland agriculture. Milkweedeventually may provide farmers with a substi-

26 . Plants: The Potentials for Etracting Protein, Medicines, and Other Usefu/ Chemicals—Workshop Proceedings

tute for irrigated crops or an alternative toother dryland crops (e.g., dryland wheat, grain,sunflowers, and sorghum) grown there. Mostof NPI’s work has been on milkweed’s photo-chemistry and extraction procedures. Althoughsome research has been done on agronomy andcrop storage, a great deal more is needed. Inaddition, the economic viability and ecologi-cal and social impacts of developing milkweedas a crop need to be examined carefully.

Fractionation of milkweed produces the fol-lowing extracts with commercial potential:pigments, rubber, and triterpenoids from non-polar solvent extraction; inositol and sucrosefrom polar extraction; and pectin from theacidic aqueous extract. The residue left afterextraction consists of fibers that can be mar-keted for various commercial uses and fibrousmaterial that is suitable for livestock feed. Thematerial that can be used for feed represents70 percent of the original plant biomass. It isequivalent to alfalfa in protein content andquality and in digestibility for sheep, but mustundergo exhaustive solvent extraction or heator acid treatment before it is rendered non-toxic.

Before commercialization of milkweed canbe successful, much additional research onagronomy, harvesting, and crop storage isneeded. Small test plots have been establishedby NPI in Utah, New Mexico, Texas, and Kan-sas. Attempts to establish stands elsewherewere unsuccessful and problems with control-ling weeds and obtaining uniform stands wereencountered. Developing effective methods ofweed control, especially when the milkweedplants are still seedlings, is critical. Harvestingresearch indicates that plants can be harvestedwith standard farm equipment such as thatused for alfalfa. Test plots gave yields of about4.3 tonne/ha, but denser planting might be ex-pected to yield between 6.7 and 9.0 tonne/ha.Storage tests indicated that although the non-polar extractable remain stable, the polar ex-tractable deteriorate over time when har-vested material is stored. Covering the storedmaterial alleviates the problem considerably.Storing the crop so that commercial process-ing could take place throughout the year would

provide considerable financial savings in plantcapacity.

Several environmental constraints must beconsidered before this crop is grown widely asa commercial crop. A major concern is that thearid and semiarid areas where milkweed cul-tivation has been tested are highly susceptibleto erosion, especially by wind. The effective-ness of zero till, crop overseeding, sod culture,narrow stripcropping, and various other op-tions should be evaluated. Another problem tobe considered is loss of soil nutrients causedby removal of plant material. Nitrogen willhave to be replaced by commercial fertilizerand possibly organic manure from cattle feed-lots. Some pest problems should also be antici-pated. Aphids are serious pests of milkweedand may become an economic liability in milk-weed plantations. Pest control using naturalpredators and both natural and synthetic in-secticides should be investigated. The dangerof milkweed itself becoming a pest is an im-portant consideration. Milkweed could causeconsiderable problems by spreading to neigh-boring fields planted in other crops. Wildpopulations of milkweed cause significantproblems as weeds in some agricultural fieldsof Minnesota.

Major technical constraints will affect theprofitability and competitiveness of milkweedcompared with other crops. First, commercialextraction and purification of inositol and pec-tin (sweeteners), which together represent 58to 73 percent of the total estimated value ofmilkweed products, are not yet commerciallyviable. Proto-commercial processing has un-covered other processing problems that mustbe resolved, and development of more efficientmethods for detoxifying the residue for live-stock feed is needed.

NPI calculated milkweed production costsusing a 2-hectare research plot. The costs werefound to be greater for milkweed than for dry-land wheat or grain sorghum. Weed control ac-counted for more than half of total productioncosts. If weed control and harvesting tech-niques were improved, production costs couldbe reduced significantly. The milkweed seeds

Ill.—Summary and Discussion of Each Workshop Paper . 27

used in the research were collected from wildplants. Seed improvement through breeding,selection, and denser spacing of the plantscould be expected to increase yields and im-prove the profitability of milkweed. The costsof erosion-control practices, not considered inthe NPI analysis, should be factored in.

The total value of milkweed products rangesfrom $511 to $645 per tonne. These figuresrepresent only the market value of the proc-essed goods. Because no figures are availableon processing costs to extract these materialsfrom milkweed, market values indicate littleabout crop profitability. Processing costs maybe considerable. For one thing, the costs of re-covering extraction chemicals might be veryhigh. As already mentioned, extraction andpurification of inositol and pectin are difficultand expensive; economically viable techniqueshave not yet been developed. The other high-value products are triterpenoids, sucrose,fibers, and livestock feed. It is questionablehow effectively sucrose and fibers from milk-weed could move into the high-volume, well-established markets for these products. Live-stock feed may prove to be competitive withother feed crops, especially on lands wherethese crops are unproductive such as areas ofthe western Great Plains. The potential of milk-weed to substitute for fossil fuels as sources ofhydrocarbons and chemical feedstocks can notbe assessed from the information given. Beforethe economic feasibility of milkweed produc-tion can be predicted with any accuracy, moredata on the costs of these products and thecosts of producing alternatives from milkweedare needed. If milkweed products were to bemoved into fossil-fuel related markets or otherlarge-demand markets, large acreages of semi-arid land might be converted to milkweed pro-duction. Ultimately, however, the competitive-ness of milkweed as either a small-demand“specialty” crop or a large-demand crop is con-tingent on the marketability of the products.A great deal more marketing research must bedone to assess milkweed’s economic feasibility.

The scale of production is a vital considera-tion to the economic viability of milkweed.Large-scale production probably is needed to

make it a profitable enterprise. Both the “spe-cialty” or high-cost products (e.g., inositol, pec-tin) and the low-cost products (e.g., livestockfeed, fiber) require large-scale production.Large amounts of milkweed are necessary toproduce even small amounts of the more val-uable products, and enough of the large-volumeproducts must be available to capture a por-tion of their markets. If the economic viabilityof milkweed were dependent on inositol andpectin, care would have to be taken to avoidflooding the markets. A balance that could sat-isfy the demands of the low- and high-volumeproducts would have to be reached. As will allnew crops, scaling-up from pilot studies tocommercial production would be the most dif-ficult step and would be contingent on milk-weed’s attractiveness to investors.

If milkweed were to become commerciallyviable, it could provide many benefits. Al-though dryland wheat, grain, sorghum, andsunflowers are grown on the western GreatPlains, the productivity of this area is not highin its contribution to total U.S. crop produc-tion. Substituting milkweed for these crops,therefore, would not reduce seriously the totalproduction of traditional U.S. food and fibercrops. The western Great Plains is a cattle-feeding center. If milkweed were to replacesome of the crops grown there for livestockfeed, it could continue to supply feed neces-sary to support this industry. Milkweed couldprovide farmers with an alternative crop, thusfreeing them from their dependence on com-modity goods. Grain prices have remained sta-ble, but operating costs have risen, so that theregion’s farming economy is severely de-pressed, If proven to be profitable, milkweedwould provide an alternative that could facili-tate the region’s economic recovery. Anotherpotential benefit would be import substitution.If the extraction problems were solved, milk-weed could fulfill the U.S. demand for inositol,all of which is imported. Milkweed triter-penoids could substitute for some imported oilsor waxes and for all domestically produced andimported pectin.

Although development of milkweed as a cropwould have many benefits and at this stage has

-

28 ● p/ants : The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

some promise, many economic, technological, crop. Its potential will have to be examined inagronomic, and ecologic problems must be re- relation to present crops as well as new arid-solved before it could be a commercially viable and semiarid-land crops being studied.

INSECT REPELLANTS, ATTRACTANTS, ANDTOXICANTS FROM ARID/SEMIARID LAND PLANTS

From the time of the early Remans until 1900only three efficient plant-derived insecti-cides—pyrethrum, hellebore, and nicotine—have had widespread use. Advances in chem-istry and improved screening techniques,however, have led to the discovery of manyplant-derived insect toxicants, repellents, at-tractants, feeding deterrents, growth inhibitors,and sterilants since the turn of the century.Some of these active compounds may be de-veloped commercially and would expand therange of available products for insect pest con-trol. New plant-derived insecticides might pro-vide substitutes for some synthetic insecticidesthat are ecologically disruptive and for othersto which insects have developed a resistance.

Arid- and semiarid-land plants are goodsources of insect toxicants and related com-pounds. Some of these biologically activechemicals are produced by the plants as de-fenses against pests and pathogens. In environ-ments of climatic stress where plant growth isslow, insect attack can be particularly debili-tating to a plant. A strong defense system maybe critical to survival and probably has beenan important factor in the evolution of arid/semiarid-land plants. Not only are these plantsgood sources of insecticides and related chem-icals but they are adapted to areas that aremarginal for production of traditional food andfiber crops. Arid/semiarid-land plants withcommercial potential offer the opportunity toexpand agriculture on land that is unproduc-tive for established crops. In addition, peren-nials such as the neem tree or mamey applemay be ecologically preferable to other cropson arid and semiarid lands which commonlyare highly susceptible to erosion.

The USDA Biologically Active Natural Prod-ucts Laboratory in Beltsville, Md., has been

studying plants as potential commericalsources of insect toxicants, deterrents, and at-tractants. Seven plants appear to be particular-ly promising. Most of these plants have beenused locally in different countries for variouspurposes including insect control. The plantsrepresent potential multiproduct crops for theUnited States and developing countries. Mostof the work done by USDA has been on extrac-tion and application of the chemicals. A greatdeal of applied research on agronomy, com-mercial processing, and marketing is neededbefore commercial production of most of thesespecies would be possible.

Calamus

Calamus, Acorus calamus is a semiaquaticperennial that can grow on dry land. The rootshave been used from ancient times in India andJapan for the treatment of a variety of ailmentsand as an insect repellant and toxicant. The dif-ferent varieties—American, Indian, Japanese,and European—have different insecticidalcharacteristics. Commercially available oilsfrom the Indian and European varieties are ob-tained either by steam distillation or solvent ex-traction. They are repellent or toxic to clothesmoths, house flies, fleas, lice, mosquitoes, andmany stored-grain insects. The Japanese varie-ty causes sterility in male house flies. Oil fromthe Indian variety is highly attractive to Medi-terranean fruit flies, melon flies, and orientalfruit flies. The roots are used in China as aninsecticide and vermifuge. The component pri-marily responsible for sweetflag’s repellencyand sterility is B-asarone which can be syn-thesized more cheaply than it can be extractedfrom plants. It is effective against the riceweevil, probably the most damaging insect pestof stored grains. Another active component,


asarylaldehyde, is commercially extracted fromthe plant material. These two compounds prob-ably would be useful as fumigants for protect-ing stored grain from insects because theypermeate grain-filled storage areas withoutleaving residues on the grain after the areas areventilated. Other potential uses of Calamuscompounds are for tuberculosis treatment, asa germicide, and in perfumery. One constraintto using Calamus chemicals is that B-asaronehas a depressant effect on the central nervoussystems of mice, rats, and monkeys. Althoughthese pharmacological properties may limit useof Calamus oil to certain applications, theyshould not prevent use of the oil for agricul-tural insect control and possibly for medicalpurposes.

Big Sagebrush

Big sagebrush, Artemisia tridentata, is amultibranched perennial that is the dominantplant of the Great American Desert. It has beencultivated in the West since 1881 as a fodderplant for range cattle. The brittle branchessometimes are used for thatch by Indians, theseeds are ground into a meal by the CaliforniaIndians, and a pollen extract is used againsthay fever. In the past, Artemisia has had vari-ous insecticidal uses. For example, sagebrushleaves and shoots were placed in granaries toprotect stored cereals from weevils and otherpests, and the water in which they weresteeped was used to kill or repel insect larvae,fleas, and locusts. An extract from sagebrushis effective as a feeding deterrent against theColorado potato beetle, a pest of growing eco-nomic importance. This pest’s resistance to in-secticides applied in potato-growing areas isan increasingly serious problem in severalareas of the world, and this resistance probablywill become more common. Only one of thecompounds responsible for the feeding deter-rent activity has been identified. It has not beensynthesized and it is unlikely that synthesiswould be economically feasible. However, thecrude, unpurified extract could be sprayed di-rectly on crops, although the potential ecolog-ical effects of doing so must be assessed first.

Neem

Neem, Azadirachta indica, a common treeof dry scrub forests in India and Burma, growson poor soils in hot, dry areas. Although allparts of the tree are repellent to insects, ex-tracts of the seeds are outstanding as repellentsand feeding deterrents for a broad spectrumof economic agricultural and household insects(e.g., Colorado potato beetles, Japanese beetles,scale insects, cotton bollworms). Seed extractsdeter at least 25 species of crop pests in theUnited States from feeding, inhibit the growthand development of others, and render otherssterile. These compounds seem to be nontox-ic to man, animals, and plants. Because theyare absorbed by the plant tissue, they offerrelatively long-lasting protection to cropseven after rain showers of high intensity. Threeantifeedants have been isolated from neem.The most potent is effective against a varietyof insect pests native to the United States. Thischemical cannot be economically synthesizedbecause its structure is so complex, but it canbe extracted in pure form.

Neem is a source of many potential productsin addition to insect antifeedants and repel-lants. Almost every part of the neem tree isused medicinally in India. Oil can be extractedfrom the seeds for soap, wax, lubricants, andlighting and heating fuel, and the residue canbe used as an organic fertilizer. Other parts ofthe tree are used in various countries for com-mercial products, including timber and cabi-netry wood, tannins, a toothpaste ingredient,and livestock fodder. Neem production couldsustain cottage industries in Asia and Africaand provide a base for large commercial opera-tions in the United States and Central andSouth America.

Neem plantations have been established innorthern Cameroon, Nigeria, Gambia, India,Honduras, and some Caribbean islands. TheU.S. Peace Corps is encouraging neem cultiva-tion in Cameroon and Gambia, and USDA hasstarted a program to develop neem commer-cially in Puerto Rico and the U.S. VirginIslands. Constraints to commercial develop-

30 Ž Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings—

ment include short-term seed viability, rapidphotodegradation by sunlight of the major ac-tive principle after field application, unpleasantsmell of the seed oil, frost susceptibility, poorgrowth on poorly drained soils, and poor agro-forestry potential because of interference withother crops and vice versa. Despite these con-straints, cultivating and processing neem seempromising. USDA is carrying out the majorbasic research on extraction and applicationof the chemicals. Universities and governmentagricultural institutes in India are focusing onapplied aspects (i.e., agronomy, product uses,marketing) of commercially developing neem.

Heliopsis Longipes

Heliopsis longipes, a perennial herb in theaster family, is native to Mexico. Heliopsisroots have been used locally in Mexico as aspice, medicine, anesthetic, painkiller, and aninsecticide against warble larvae found in cat-tle wounds. Root extracts have also been effec-tive against houseflies, mosquitoes, body lice,bean weavils, and other household and agri-cultural pests. The active ingredient has beenisolated, identified, and prepared synthetical-ly, but extraction is more economical than issynthesis. Some transplanting and cultivatingexperiments using wild plants have improvedplant biomass yields. However, in spite of thesucculent character of the roots, they dry outwhen exposed to air and will not grow whentransplanted. Therefore, care must be takenwhen transplanting wild plants that the rootsare kept moist or plants are replaced immedi-ately.

Mamey

Mammea americana is an edible fruit-bearing tree found in Latin America and theCaribbean. The flowers, fruits, seeds, andleaves are effective against a wide variety ofinsect pests including melonworms, fleas,ticks, lice, fall armyworms, mosquitoes, andcockroaches. Two major insecticidal com-pounds have been isolated and identified, andmethods to extract them have been developed.People have used the plant for many other uses,

but no serious attempt has been made at ex-port or commercial production. The wood isused in construction and cabinetmaking; theflowers are used to make a liqueur in theFrench Antilles; the fruit is eaten raw or isstewed and made into a drink or candles; andgum from the bark extracts chiggers from thefeet, The tree is cultivated on Caribbeanislands, and in Mexico and Central and SouthAmerica for the edible fruit. Mammea’s poten-tial as a commercial crop in southern Florida,Puerto Rico, and the U.S. Virgin Islands shouldbe investigated.

Basil

In addition to its widespread use as a spice,Ocimum basilicum, or sweet basil, is recom-mended for use against gastric disorders, ma-larial fevers and skin diseases, and for insectcontrol. The oil from basil is an effective re-pellant and larvicide for mites, aphids, andmost species of mosquitoes; a growth inhibitorfor milkweed bugs; and an attractant for fruitflies. Most repellant compounds in the oil havebeen identified. The oil content of plants variesdepending on soil fertility and weather imme-diately preceding harvesting. Because extrac-tion is simple and inexpensive, synthesis is notcommercially practical. The plant is cultivatedeasily and can be grown and its oil producedin many places in the United States.

Mexican Marigold

Tagetes minuta is an annual that is native toCentral and South America but also grows inparts of East Africa, India, Eastern UnitedStates, South Africa, and Spain. The oil pro-duced by the seed, leaves, and flowers isstrongly repellent to blowflies and is useful inthe Tropics as a blowfly dressing for livestock.The leaves are used locally in Africa and In-dia to repel mosquitoes and safari ants. The oilis more toxic to mosquito larvae than DDT. Theplant also has potential medical uses and theroots exhibit fungicidal and nematocidal activi-ty. An extraction method for the essential oilhas been developed. Although two larvicidalcompounds and the growth deterrent can be

III.—Summary and Discussion of Each Workshop Paper ● 31

synthesized, laboratory synthesis of several ofthe pesticidal compounds gives low yields andunreliable results. Because large-scale cultiva-

tion of the plant should be feasible, extractionof the essential oil seems to have the greatestcommercial potential.

Marine plants are represented both by sea-weeds, macroscopic forms that mainly live inshallow coastal waters, and by phytoplankton,free-floating, widely distributed unicellularplants. Although a few flowering plants (angio-sperms) are abundant in shallow waters, themajority of marine plants are algae, typified bytheir lack of a vascular system. Taxonomical-ly, algae are highly diverse. Their highlyspecific coloration has served as a basis ofclassification; marine algae are divided into atleast 12 distinct groups based on color (e.g., redseaweeds, brown seaweeds, blue-green algae,etc.). While no precise estimate has been made,it is thought that well over 100,000 species ofmarine algae exist. Biogeographically, marinealgae live in all parts of the ocean and frequent-ly are found in extremely high concentrations.Although precise figures are difficult to sub-stantiate, the primary productivity of 1 acre ofthe marine environment may be twice that ofa Midwest cornfield.

Marine plants have evolved unique and high-ly specialized biochemical pathways to adaptto their unique seawater medium and survivalpressures. The marine environment is rich inchloride and bromide salts and other chemicalentities such as sulfate. Marine plants use theseelements in biosynthetic processes to producecompounds that are unique to the marine en-vironment. Many marine plants have evolvedtoxins and deterrents as protection againstabundant and freely migrating predators. Eventhough the same evolutionary pressures haveproduced similar responses in terrestrialplants, the defensive chemicals from marineplants are novel and represent interesting newchemical species that are unprecedented in ter-restrial sources. Other chemicals representadaptations to the physical environment suchas wave shock and motion. For example, com-plex polysaccharides (complex sugars) act to

reduce the surface tension of seawater. Theseconstituents, too, are highly specific to marinealgae.

Marine algae have been used in differentcountries for a long time as sources of foods,food thickeners and flavorings, animal fodder,soil manure, potash, and herbal medicines. Forexample, “Nori” and “Wakami” have becomeintegral parts of Japanese diets, and over 18,000tonnes of Nori are commercially producedeach year. Numerous species of marine algaeare used in China as herbal medicines to treatmany maladies ranging from intestinal prob-lems to sunstroke.

A classical use for seaweeds has been the ex-traction of halogens and potash. Brown algaewere used for several decades as the majorsource of iodine, and the red seaweeds wereused occasionally for deriving bromine. TheU.S. Pacific coast between 1910 and 1930 wasthe site of a flourishing potash industry basedon the high potassium concentrations found inlocal brown algae. The uses of marine algae assources for elemental halogens, potash, andcrude food-thickeners largely were curtailedby the mid-1900’s as other, more cost-efficientsources were developed. But also during thisperiod, many currently used algal products,particularly algal polysaccharides, became es-tablished.

A well-established industry in the UnitedStates now harvests marine seaweeds and ex-tracts agar, carrageenan, and alginate. Agar isfound in many species of red algae and is usedmainly as a gelling agent and thickener infoods but also as a biochemical adsorbent, cul-ture and nutrient medium for bacteriologicalresearch, and major nutrient medium for theindustrial production of antibiotics. Carrageen-an, which is also extracted from red algae, haswidespread use within the food industry. The


total annual market value of polysaccharidesderived from red algae is about $200 million.Alginate, extracted from brown seaweeds, isparticularly valuable for incorporation into in-dustrial products and processes. It is used forits thickening, emulsion stabilization, and gell-ing properties.

Even though the majority of marine algalproducts come from the readily collectedmacroscopic forms, several products are beingproduced by the culture of unicellular forms.The green alga Dunaliella, for example, recent-ly has been established in mass culture as acommercial source for glycerol (glycerine) andthe orange pigment beta-carotene. Glycerol isused in the manufacture of many products(e.g., printing ink, antifreeze) and beta-caroteneis used to impart color and provide vitamin Ain animal feeds and human foods such as mar-garine and is also used as a sunscreen agent.

Several algal species have been used consist-ently in the biomedical sciences. In particular,active components of red algae Digeniasimplex and various Chondria species are ex-tracted, purified, and marketed as drugs inAsia. No other examples of successfully algae-derived pharmaceuticals exist, but there cer-tainly is a great potential for further develop-ment in this area.

Even though relatively little basic chemicalresearch has been performed on marine algae,mass culture techniques, both in the ocean it-self and in controlled coastal facilities, havegreat potential to provide industrially signifi-cant quantities of marine algae. Funding fromthe Department of Energy (DOE) through theSolar Energy Research Institute (SERI) andseveral other agencies has supported work onrequirements for effective algal growth. Marinealgae probably will be a focus of considerableattention over the next decade as we investi-gate new resources for both energy and indus-trial product development.

Although relatively few algal products havebeen developed successfully by industry, thepotential for the discovery and development ofa plethora of unique new products seems un-

limited. A few of the most notable areas for ex-ploitation in the near future are summarizedbelow.

Biomass Conversion

Work already has begun on assessing algaeas sources of biomass for conversion to meth-ane gas, ethanol, and other useful chemicals.Algae are efficient photosynthetically and arecultured conveniently in the open ocean,ponds, or controlled culture vessels. However,problems with fertilization of cultured sea-weeds must be solved. Biomass conversionprocesses are not cost efficient, but continu-ing research is needed so that the technologywill be available when required in the future.

Pharmaceutical Development

Although numerous biomedical uses for algalpolysaccharides have been established, themajority of applications involve use of theirphysical properties rather than their physiolog-ical activities. A surprising percentage of algalpolysaccharides, however, show antiviral ac-tivity. For example, a red seaweed extract con-tains an antiviral compound that is effectiveagainst Herpes simplex, a virus responsible fora disease that has reached epidemic propor-tions in the United States. Several substanceswith antibiotic and antitumor activity havebeen isolated from macroscopic seaweeds. Al-though few comprehensive studies of micro-scopic algae have been reported, some of thesealgae exhibit antimicrobial activities and areknown to produce powerful toxins. However,almost no information exists on the pharma-cological potentials of the tens of thousands ofmicroscopic marine algae mainly because ofthe difficulty in purifying a single species ofunicellular algae and growing it for biomedicalstudies. Much could be learned from such re-search.

The slow rate of developing new marinepharmaceuticals clearly can be linked to thelimited involvement of the major pharmaceu-tical companies. Pharmaceutical firms do nothave in-house expertise and marine biological


laboratories in the past have not employedscientists with biomedical expertise. This ischanging, however. Major programs have de-veloped under the Department of Commerce’sSea Grant Program. The Sea Grant effort in bio-medical development is an effective blend ofacademic and industrial (basic and applied) re-search that is yielding fruitful results. The SeaGrant project, “Marine Chemistry and Phar-macology Program, ” at the University ofCalifornia, for example, has discovered morethan 75 pure compounds with potential bio-medical use and the project has emphasizedcollaboration with the pharmaceutical indus-try. This collaboration is the vital link to en-sure that basic marine research finds its wayto the industry that is capable and interestedin developing new products.

Other governmental agencies have had morelimited involvement in marine biomedical de-velopment. For example, the National CancerInstitute has dedicated significant resourcestoward the isolation of new antitumor drugs.Here again, the need to involve basic marinescientists to locate, identify, and quantitatesuitable marine species for study was underem-phasized, and considerable difficulties wereencountered.

Agricultural Chemicals

Many synthetic pesticides are halogenatedcompounds. Since halogenation is a naturalprocess in marine plants, the compounds pro-duced are likely to possess agrichemical activi-ty. Initial collaborative investigations indicateconsiderable promise. Of 12 algal compoundsassessed in herbicidal and insecticidal bioas-says, 9 showed some activity, and 1 was near-ly equivalent to DDT in insecticide activity.

Here again, the success in developing marinealgal agrichemicals lies in developing a closerelationship between academic and industrialresearch. A limitation on commercial develop-ment of marine extracts is that little Govern-ment funding is available outside of USDA.Agricultural research funding should be ex-panded in the United States to include a greatercomponent of academic research.

Food and Food Products

In addition to agar, carrageenan, and algi-nate, marine algae are recognized sources ofnumerous useful food products, includingcooking oils. Although the seaweeds usuallyare low in protein, many phytoplankton arerich protein resources. The blue-green algaeare potential protein resources, and one blue-green algae, Spirulina, has already been mar-keted as a health food.

Enzymes

Marine enzymes, while almost completelyunknown, could be used beneficially in in-dustrial processes.

Industrial Chemical Feedstocks

Both macroscopic and microscopic marinealgae could be cultured to yield hydrocarbonmixtures that could be used as diesel fuelwithout further purification. Other compoundsfound in most marine algae could be used inthe plastics industry. Notwithstanding thework on agar, carrageenan, and alginate, phy-toplankton, in general, have been virtuallyunexplored for their polysaccharide com-ponents even though it is highly conceivablethat they could yield new and importantproducts.

Needs for DevelopingMarine Algal Resources

Small-volume products, such as a specialtypharmaceutical, could be developed from na-turally occurring populations but, in general,effective use of marine algal resources, espe-cially unicellular algae which cannot be col-lected in pure form, must be coupled with massculture technology. Mass algal culture andproduct derivation should be developed keep-ing in mind multiple-product development. Thealgal resources that should be considered fordevelopment are those that produce more thanone marketable product to offset the relative-ly high production costs.

34 Ž Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

A basic problem in considering developmentof marine algal resources is that there has beeninsufficient research on potential productsfrom algae. Although a significant number ofchemical investigations have been conductedon seaweeds, there have been few on unicel-lular algae. Considerable resources are beingdevoted to developing algal-culture technolo-gies, but generally these studies are not predi-cated on a solid knowledge of algal chemistry,genetics, nutrition, and reproduction. In addi-tion, mass culture techniques must be refined.

Biotechnological advances, particularly inthe field of marine genetics, can be expectedto have sizable impacts on use of marine re-sources. Marine products and biochemicalprocesses are unique, and this unique gene

pool could be highly useful in future productdevelopment.

A significant problem lies in the poorly de-veloped working relationships between Gov-ernment, universities, and appropriate in-dustries. Government funding agencies havedifficulty supporting applied research, par-ticularly as it may benefit a single private enter-prise. The university system finds its relationswith industry strained by patent and proprie-tary information problems. Close cooperationbetween these entities will be necessary, suchas has been developed by the Sea Grant Pro-gram. As this tripartite collaboration develops,it seems likely that marine algal species willbecome major sources of future products.

ANTICANCER DRUGS FROM THE MADAGASCAR PERIWINKLE

Although literature sources cite 3,000 plantspecies used or recommended for cancer treat-ment in different parts of the world, only onespecies has been used to produce a commer-cial cancer-chemotherapy drug. This plant isthe Madagascar periwinkle, Catharanthusroseus. It is an herb or subshrub foundthroughout the Tropics and cultivated as a gar-den plant worldwide. The development of theperiwinkle anticancer drugs from isolation andpurification of several Catharanthus alkaloidsto laboratory and clinical testing and sub-sequent marketing of two of them representsa tremendous success story in the field of plant-derived pharmaceuticals. In the short timesince first clinical use, these alkaloids havebecome two of the most valuable cancer chem-otherapy treatments available.

The Madagascar periwinkle was one of 440plants selected for study in an Eli Lilly plant-screening program for plant-derived drugs.The plants were chosen on the basis of careful-ly assessed reports of folklore use and reportedalkaloid contents. Alkaloids, complex nitrogen-containing plant compounds, are often physi-ologically active. They are the most commonactive ingredients in many plant-derived med-

icinals. C. roseus was reported to containalkaloids and folklore uses indicated that it con-tained biologically active compounds. Past useof the plant had been based on its blood-sugar-lowering properties, suggesting to Eli Lillyresearchers that it might provide a substitutefor oral insulin. When tested at Eli Lilly, how-ever, the plant initially did not exhibit hypo-glycemic activity but did show strong and re-peated antitumor activity when subjected to anantileukemia model. Ironically, the periwinklehad not been one of the 3,000 plants cited ascancer treatments in reports of folklore use.

Standard isolation and purification tech-niques were not successful in extracting theantitumor agents from the plant, so new extrac-tion methods were devised. Using these newtechniques (selective extraction followed bycolumn chromatography and gradient pH tech-nique), Eli Lilly isolated 55 alkaloids from C.roseus. A total of 74 alkaloids, 3 of which werepreviously unknown, have been isolated frommature periwinkle plants, and 21 additionalcompounds have been isolated from immatureplants. This extraction work and subsequentsterochemical research to determine thealkaloids’ chemical structures represent signifi-cant advances in the field of photochemistry.


Two of the periwinkle alkaloids that showedpotential as antitumor drugs have reached themarketplace. These are leurocristine (LC)-whose generic name is vincristine and ismarketed by Eli Lilly as ONCOVIN-and vin-caleukoblastine (VLB)-known generically asvinblastine. Although LC and VLB are closelyrelated chemically, they have different poten-cies against tumors because of minor differ-ences in their molecular structure. Leurocris-tine, called a “miracle drug” because it wasplaced on the market only 4 years after initialdiscovery and is extremely valuable in cancerchemotherapy, was responsible for a resur-gence of interest in plants as sources of anti-tumor compounds. LC is most effective in treat-ing childhood leukemia of the lymph system;alone it can induce a 50-percent response ratein children with acute lymphocytic leukemia,and in combination therapy gives a 90-percentresponse rate. It is also effective against a varie-ty of human cancer, including Hodgkin’s dis-ease, breast cancer, and primary brain tumors.VLB is used mainly in treating lymph tumors,especially in Hodgkin’s disease patients. Itshows a 70- to 80-percent response rate in pa-tients with lymphoma, is highly effectiveagainst testicular tumors, and shows activityagainst various other cancers.

These two compounds and other dimericCatharanthus alkaloids showing similar anti-tumor activity represent a new class of anti-tumor agents. Although their mechanism of ac-tion still is not completely understood, it seemsto be based on disrupting cell division, thus ar-resting tumor growth.

Chemotherapy treatments have improvedover the last two decades so that they are ef-fective alternatives for or additions to radiationand surgery as cancer therapies. Much of theimprovement in chemotherapy is the result ofcombination drug treatments in which variousdrugs with different mechanisms of action areused together. The periwinkle alkaloids are im-portant in these multidrug therapies and havebeen key elements in the increasing sophistica-tion of cancer treatments.

The potential of Catharanthus roseus alka-loids as medicines is by no means exhausted.A great deal of chemical work has yet to bedone both on LC and VLB and on the other per-iwinkle alkaloids showing antitumor activity.One alkaloid that seems particularly promisingand needs more research is leurosidine. Clin-ical tests for an experimental leukemia modelin mice indicate that leurosidine is the mostexperimentally active Catharanthus antitumoralkaloid. However, the yields from periwinkleplants are low and high doses are needed fortesting, so sufficient amounts of leurosidine forcomprehensive clinical trials have never beenstockpiled. Another compound that has notbeen fully investigated is an unidentifiedchemical called “super leurocristine” whichdisplays 300 times more antitumor activity thanleurocristine/leurosidine fractions. This wasnever clinically tested and the high cost tostockpile the active fraction for testing now isconsidered prohibitive.

Chemical derivatives of Catharanthus alka-loids also deserve additional research. Sinceslight chemical alteration may produce dra-matic changes in dose-limiting toxicity of acompound, work on chemical derivatives mayuncover potentially marketable compoundswith more benign side effects than the origi-nal compound.

Another area that should be explored furtheris the conversion of leurocristine to vincaleu-coblastine. The yield of leurocristine fromperiwinkle plants is 0.0003 percent, the lowestyield of any commercially used medicinalalkaloid. The yields of VLB are considerablyhigher, and since the chemical structures of thetwo are closely related, it maybe possible andeconomically beneficial to convert VLB intoleurocristine. This conversion has been donesuccessfully in the laboratory, but a great dealmore work must be done before it can becomea commercially viable operation.

Attempts to synthesize VLB and LC havebeen unsuccessful. This should continue to bea research priority. Until synthetic equivalents

36 • Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

can be produced, the active compounds willhave to be extracted from periwinkle plants.Catharanthus roseus plants were initially col-lected from the wild. As it became apparentthat there would be a demand for thousandsof tons of plant material, periwinkle cultivationbegan on farms in India and Madagascar. Toavoid the risk that the supply of raw materialmight be cut off and to guarantee an uninter-rupted supply of plants, cultivation was startedin Texas.

The success of the work on the Madagascarperiwinkle was dependent on two major fac-tors: careful plant selection and the availabil-ity of an appropriate test system (an experimen-tal mouse tumor) to monitor the effectivenessof purified active compounds. Plant selectionwas based on alkaloid content reported fromfolkloric use. Folkloric use can be a valuableindicator of the desired chemical activity ifcare is taken in interpreting the reports. If not,such reports can be misleading. Another meth-od by which to choose plants for screening israndom selection. The success of random se-lection could be improved by considering bo-tanical and chemotaxonomic relationships be-tween the plant to be tested and plants ofknown photochemistry and biological activi-ty. An experiment mouse tumor served as anappropriate biological test system to monitorthe purified alkaloids for the desired activity.

Perhaps the major lessons to be learned fromthe research and development (R&D) of Cath-

aranthus alkaloids as anticancer drugs are thatpharmaceutical drugs can be obtained from re-newable resources rather than petroleum-derived synthetics and the developing newplant-derived drugs can be profitable. Despitethe potential of plants for providing valuablenew drugs and high profits to the companiesdeveloping them, U.S. pharmaceutical firmshave eliminated their plant-screening programsand the Federal Government has discontinuedits program for plant-derived anticancerdrugs. * This disinterest is not because thepotential for finding valuable drugs in plantshas been exhausted. Only a tiny proportion ofthe Earth’s higher plant species has been phy-tochemically screened, and these species repre-sent a bank of potentially important drugs. Asalready mentioned, more than 3,000 plantshave been cited as possible anticancer treat-ments, not to mention known activity of nu-merous other plants that could be valuable forother medical uses. This disinterest in plantscreening for pharmaceuticals is not universal.The Germans, Japanese, Russians, and Chinesehave major investments in exploring potentialplant sources for pharmaceuticals and otherchemicals. Perhaps the reasons for the neglectof this research in the United States should beexamined and decisions to discontinue workreconsidered.

*See the paper by Farnsworth and Loub in the appendix,

STRATEGIC AND ESSENTIAL INDUSTRIAL MATERIALS FROM PLANTS

The United States depends on other nationsfor many materials and manufactured productsimportant to U.S. industry, including agricul-turally produced plant substances and minedmaterials. Some of these products are or couldbe agriculturally produced in the United Statesand used as industrial materials or as renew-able replacements for petroleum as sources offeedstock in the chemicals industry.

Some industrial materials are classified as“strategic, ” or critical to national defense.

Three “strategic” industrial materials arecastor oil and sperm whale oil, * which arehigh-quality lubricants, and natural rubber.Law requires that sufficient supplies of thesematerials be acquired and stored in the UnitedStates to meet national defense needs in caseof war. “Essential” materials are those required

*The Endangered Species Act of 1970 prohibits productionor importation of sperm whale oil so it is not stockpiled in theUnited States. A substitute for this high-quality lubricant mustbe provided. Jojoba is a promising substitute.

III.—Summary and Discussion of Each Workshop Paper Ž 37

by industry to manufacture products dependedon daily. Essential materials include itemsmanufactured or extracted from plants (e.g.,waxes, oils) and replacements for petroleumused as feedstock in manufacturing syntheticmaterials (e.g., plastics,. chemicals).

The United States imported an estimated $23billion worth of agriculturally produced in-dustrial materials and petroleum for feedstockduring 1979. Average annual growth in importsfor 1975-79 was 10 percent. The manufactureof synthetic organic chemicals consumed about470 million barrels of petroleum as feedstockin 1978, valued at $15.1 billion. U.S. industrypurchased nearly $2 billion worth of agricul-tural imports, $3.5 billion worth of newsprintand other paper products, and $2 billion worthof chemicals extracted from plants and petro-leum.

Technologically, it seems possible to producedomestically nearly all the aforementioned im-ported agricultural products and materials andto substitute domestically produced agricul-tural products for the 470 million barrels of im-ported petroleum feedstock, with a net savingsof about 270 million barrels of imported oil peryear. Table 1 lists some of the potential domes-tic crops and what they might replace. Suffi-cient research indicates that their domesticproduction and use in the chemicals industry

Table 1 .—Potential Domestic Crops and Uses

GuayuleCram beJojobaLesquerellaVeronia-StokesiaKenafAssorted oilseedsHevea natural rubber,

resinsHigh erucic rape oil and

petroleum feedstocksSperm whale oil and

imported waxesCastor oilEpoxy oilsImported newsprint and

paperPetrochemicals for

coatings and otherindustrial products

SOURCE: Office of Technology Assessment.

are chemically feasible, agronomically possi-ble, and economically viable, although moreagronomic and economic research must beundertaken before definitive conclusions canbe drawn about their substitution feasibility.Production of only one-third the annual domes-tic demand for strategic materials would elim-inate the need to stockpile them, could save atleast $1 billion of public money over the next18 years (otherwise spent in acquiring andmaintaining strategic stockpiles of natural rub-ber and castor oil), and could provide replace-ments for sperm whale oil. Producing 100 per-cent of the strategic and essential industrialmaterials or their replacements might reduceU.S. foreign outlays by about $16.5 billion an-nually at constant 1979 dollars and demandlevels.

Production of substitutes for one-third to one-half the industrial materials purchased abroadwould demand about 60 million acres of crop-land. The United States has about 413 millionacres of cropland and about 36 million acresof pasture and other land in farms that easilyand inexpensively could be converted to cropproduction. Another 96 million acres of landcould be converted to crop production withmore difficulty and expense. The Nation’s totalcropland base (land capable of sustained cropproduction under intensive cultivation byknown methods) is therefore about 540 millionacres. According to USDA, about 462 millionacres of cropland will be needed in 2030 tomeet domestic and foreign trade demands forfood and fiber. This would leave 78 millionacres of the cropland base to meet other pro-duction needs. If 60 million acres were usedfor industrial and strategic materials produc-tion, 96.8 percent of the Nation’s croplandwould be used.

The question of land availability must be ex-amined carefully. The land resource base thatwill be needed or available for food, fiber, andindustrial chemical crops over the long termwill depend on certain unpredictable circum-stances including international trade (e.g., levelof export sales, price of petroleum); changesin land productivity; and quantity and qualityof agricultural land being lost to urban devel-

38 • Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

opment, water impoundments, etc. Anotherissue is the feasibility of converting farmlandand land in other uses to the production of in-dustrial crops. Lands currently in agriculturalproduction could be converted to industrialcrops more easily than uncultivated lands andlands owned or operated by nonfarmers. Itwould be largely a question of the economictradeoffs of one crop against another. If a newcrop is sufficiently more profitable than an oldone, it probably would be planted. However,the scant amount of information on motiva-tions of persons owning farmland that is notfarmed indicates that much of this land isowned for esthetic, recreational, or speculativepurposes and could not be shifted into agricul-tural production easily. In this case, puttingthese lands into industrial crops is not astraightforward economic issue. The landwould have to be leased or sold to farmers, andthis transferal of landownership or controlcould be a constraint to new-crop development.

Another land-related question that should beraised is whether a 100-percent” utilization rateof the agricultural land base is optimal. Seriousthought should be given to possible land qualitydegradation, especially from cultivating mar-ginal lands. Clearly, some agricultural landscould benefit from substituting a more ecolog-ically suited crop for a traditional crop (e.g.,crambe in areas marginal for corn or wheat),but care must be taken that increased use ofthe Nation’s agricultural land base does notoutpace development of appropriate croppingsystems that minimize ecological degradation.In addition, the need for a land reserve thatcould be tapped in the event of unforeseencircumstances should be considered.

Current research on new crops is extremelylimited. Only guayule, jojoba, and crambe arebeing grown on semicommercial scale acre-ages. Federal funding for research is greatestfor guayule because of its importance to themilitary. However, the total 1981 public ex-penditures for guayule research totaled only $3million. Research commitments to all other po-tential substitute commodities discussed herewere considerably less.

Little additional basic chemical research isneeded for these commodities. Chemical en-gineering to develop efficient, economical ex-traction and processing systems, however, isneeded. Because of the present lack of risk cap-ital in the private sector, public support of suchresearch probably would be necessary if theseplant materials are to be commercialized. How-ever, in 1982, the Office of Management andBudget imposed rigid guidelines governingFederal research and directed USDA to termi-nate any ongoing research of a commercialnature. Byproduct-use research also will beneeded to assess commercialization potential.The value of byproducts is unknown becauseinformation on their potential uses is limited.

The greatest need for research on these po-tential commodities in the immediate future isin the areas of plant breeding and agronomy.Most of these new crop materials being grownin research projects are from wild or nearlywild plants. Genetic improvements are neededto increase seed and oil yields and predictabil-ity of the plant under cultivation. Littleagronomic research has been done for poten-tial new commodities other than crambe andguayule.

The economic benefits of using domestic pro-duction to replace agricultural imports and tosubstitute renewable agricultural materials forpetroleum as feedstock in the chemicals indus-try depend on:

● the relative costs of substitutes and currentsources of these materials,

● the degree of profitability in producingnew agricultural raw material, and

● the level of subsidization required by theagricultural industry to meet national stra-tegic and essential materials needs.

One study of the commercial feasibility of es-tablishing a domestic rubber industry based onguayule estimated that the price for importedrubber and the costs of domestic productionwill converge in the late 1980’s, making itequally as attractive to produce the materialdomestically as to import it.

III.—Summary and Discussion of Each Workshop Paper • 39

The primary consideration in substitutingagricultural commodities for petroleum asfeedstock in the chemicals industry is the priceof petroleum. In industrial uses, seed oils couldsell at a higher price per pound than petroleumwithout increasing the price of the final chem-icals produced because these plants yield rel-atively pure chemicals that could be used withlittle processing. Extraction of the same chem-icals from petroleum is complex and expen-sive. The economic viability of substitutingagricultural commodities for petroleum cannotbe assessed until semicommercial productionand prototype-scale extraction are undertakenso that the values of the chemicals producedcan be compared. Genetic improvement couldmake these substitutes more economicallycompetitive.

During recent years, the Federal Governmenthas spent between $7 billion and $14 billionannually to subsidize production of commod-ities that are already in surplus. If this subsidywere spent instead to encourage the domesticproduction of imported plant materials or toprovide substitutes for petroleum feedstocks inthe chemicals industry, the average subsidy onthe 60 million acres required to reduce importsby half would fall between $116 and $233 peracre per year. If 60 million acres are used toproduce such commodities, on-farm employ-ment could increase by about 155,000 jobs.This also would generate indirect income andemployment benefits to agriculturally relatedenterprises.

Evidence suggests that oil-conservation ef-forts in the United States and other importingcountries already have had major dampeningeffects on world production and pricing. In theevent the world oil price decreased as theUnited States switched to agricultural alter-natives, the United States would have in-creased leverage with oil suppliers as long asits option to substitute agricultural commodi-ties were kept open.

Domestic production of imported agricultur-al materials and petroleum substitutes wouldhave foreign policy implications. Exporting na-tions would react unfavorably to U.S. importsubstitution, whereas other nations importing

these materials would benefit from resultinglower prices. It would be important for U.S.domestic agricultural policy and U.S. foreignpolicy on import substitution to be consistent,and Federal policy makers would have to becautious about geopolitical problems that mightarise from Government support of import sub-stitution efforts.

The key short-run issue for farmers, agricul-tural firms, and the Federal Government wouldbe whether to subsidize production of newagricultural commodities instead of continu-ing to subsidize surplus production or supportagreements to take land in surplus commodi-ties out of production. Incentives for con-sumers of intermediate industrial materials andend-products to support substitution of domes-tically grown commodities would be lowercost, assurance of continued supply, anddecreased price fluctuations.

Four domestic policy shifts would be neededto move toward domestic control and produc-tion of strategic and essential industrialmaterials:

1.

2.

3.

4.

from dependence on foreign nations foragriculturally based strategic materials todomestic supply of them;to a national policy of encouraging agri-cultural research that has foreseeable com-mercial application, including participa-tion with the private sector in commercial-ization activities, partly research and part-ly commercial in nature;to spend Federal funds to support produc-tion of useful agricultural commoditiesrather than supporting production of sur-plus commodities or pay for farmers to dis-continue production; andto look at domestic production of agricul-turally produced materials as a way ofusing our farm-production potential ratherthan depending on foreign trade.

Sufficient resources should be committed tothe kinds of activities suggested hereto use ordiscard, with just cause, the many developmentoptions that exist for domestic production ofimported strategic and essential industrialmaterials.


INFORMATION USEFUL TO PLANT-DERIVED DRUG PR0GRAMS

Higher plants are essential ingredients of alarge proportion of U.S. prescription and over-the-counter drugs. From 1959 to 1973, new andrefilled prescriptions containing plant productsrepresented 25 percent of all prescriptions dis-pensed from community pharmacies in theUnited States. The dollar cost to the consumerfor prescriptions containing active ingredientsfrom higher plants was $1.6 billion in 1973. Ad-ding an almost equal amount to this figure forplant-derived drugs dispensed from other out-lets (e.g., out-patient hospital pharmacies, ex-tended care facilities, Government hospitals),an estimated total cost to the consumer was $3billion in 1973. The current annual cost to theconsumer for plant-derived drugs is estimatedto be at least $8 billion. In addition to the pre-scription drugs, the sale of herbal teas in theUnited States is estimated at about $200 millionannually, and the sale of over-the-counter(OTC) drugs obtained from plants is probablyat least $1 billion.

National Prescription Audit (NPA) data showthat 41 species of higher plants yield all of theplant-derived prescription drugs. An additional62 species of plants entered the prescriptionmarket in the form of crude extracts with ac-tive principles. Less than 50 pure compoundsfrom plants were represented in the prescrip-tions analyzed. Virtually all of these com-pounds are produced commercially by extrac-tion of plant material or by chemical modifica-tion of extracted plant compounds. Althoughmost of these drugs have been synthesized, syn-thesis is not commercially feasible, with fewexceptions.

Although much has been written in scientificjournals of this country and abroad that shouldspark industrial interest to invest in researchon plant extracts, interest in this country hasdeclined. In 1974, the American pharmaceu-tical industry’s total research and developmentbudget for pharmaceuticals for human use was$722.7 million, Only one firm was involved indirect research to explore plants for newdrugs with an annual program budget less than$150,000. Today, there are no U.S. pharmaceu-

tical manufacturers involved in a research pro-gram designed to discover new drugs fromhigher plants.

Of the developed countries, only West Ger-many and Japan pursue development of newplant-derived drugs. West German studies aresupported by many small firms but have notcaptured the interest of large pharmaceuticalcompanies. Japanese academicians receivegovernment and industrial support for researchon plant drugs, and Japanese pharmaceuticalfirms have major research departments dedi-cated to the same goal. Scientific papers fromJapanese research laboratories relating to drug-plant development outnumber those from theUnited States by at least tenfold, and Japanesepatents for plant-derived biologically activesubstances outnumber those from the UnitedStates by a factor of at least 50.

Plant sciences have not had a voice in U.S.corporate or high-level governmental decision-making, except in the area of basic agriculture.Important decisionmakers connected withdrug development apparently are unaware ofthe extent to which plants contribute to oursource of drugs. During the past three or fourdecades, research administrators rarely havebeen trained in plant sciences. Further, sciencehas advanced to a point where interest has notbeen on the intact organism—plant, animal, ormicrobe—but rather on the cell, cell contents,and cell biochemistry. Typical industrial drugdevelopment increasingly has involved synthe-sis of molecules based on structure-activity re-lationships, and natural product drug develop-ment has been restricted to antibiotic produc-tion by micro-organisms.

Most useful drugs derived from higher plantshave been “discovered” through scientific in-quiry into alleged folkloric claims of therapeu-tic effects, although in recent years the randomcollection of plants followed by pharmacologicevaluation has been pursued. A major programof the National Cancer Institute (NCI) involv-ing the “screening” of plants randomly col-lected worldwide ended in late 1981. This pro-

III.—Summary and Discussion of Each Workshop Paper ● 41

gram, which was started in about 1956, testedsome 35,000 species of plants for antitumor ac-tivity in laboratory animals. Although a largenumber of highly active agents were discov-ered by the NCI program, some remain to bestudied in humans and as yet none have beenapproved for use in humans by FDA.

Industry’s development of useful drugs fromhigher plants during the past 30 years has notbeen more productive than Government ef-forts. Since 1950, pharmaceutical companieshave produced only three plant-derived drugsthat have reached the U.S. prescription market:reserpine, vincaleukoblastine, and leurocris-tine. * The total number of industry researchdollars required to discover these drugs hasbeen miniscule compared with the cost of plac-ing synthetic drugs on the market. One reason forthis might be that much of the unexplored florain the world is found in tropical or semitropicaldeveloping countries that may be regarded asunstable supply sources for an internationalmarket. However, another country might serveas a source of wild plants or plant supplies maybe obtained through cultivation or other tech-niques (e.g., tissue culturing). A second reasonindustry cites for lack of screening and plant-drug development is that patent protection isless secure with natural products than withsynthetics. There is little evidence to back upthis claim.

Data of value in organizing and implement-ing an effective plant-derived drug develop-ment program are difficult to obtain throughavailable online drug data bases or from pub-lished reports. In addition, much of the usefulpharmacological data on plant extracts werepublished prior to the earliest data covered byall available online data bases. Pharmaceuticalcompanies are reluctant to share data derivedfrom testing plant extracts, even if the data arenegative and are of no commercial interest tothe firms. Negative data are as important aspositive data in a broad plant-based develop-ment program; knowledge of past negative re-search can help other researchers in selectingnew plants for study without duplicating past

*See paper by Svoboda in the appendix.

work. NCI published negative data regularlyat the beginning of the plant screening pro-gram, but this soon ended.

If plants to be screened for a plant-deriveddrug program are not to be screened random-ly, they should be chosen on the basis of bestavailable information (table z). Informationsources will vary, but probably would include:

1. Ethnomedical data—anthropological writ-ings, folkloric writings, popular books,pharmacopoeias, etc.;

2. Experimental data on plants—abstractingservices (e.g., Chemical Abstracts), bibli-ographic online data bases, review articles.

After collection of available pertinent data,drug development programs proceed through:

● plant collection,● bioassay for evaluation of crude plant ex-

tracts,● isolation and identification of biological-

ly active chemicals from plants, and● clinical evaluation and marketing.

Few pharmacologists are experienced in eval-uating crude plant extracts or are interested indeveloping bioassay systems outside their ownarea of interest. Even though a program isdesigned to identify only one or two types of

Table 2.—information To Be Included in a Data Basefor Drug Development From Plants

Plant characteristics: Latin binomial effects claimed;common names; place of collection; geographicrange; parts of the plant studied.

Ethnomedical uses: Crude plant material or type ofextract used to prepare the dose; dose employed,administration, and dosage regimen; beneficial effectsclaimed; side effects reported.

Chemical constituents: Part of plant in which specificconstituent is present; range of percentage yield ofthe chemical; data on seasonal or other variations inchemical quality or quantity.

Experimental testing: Type of solvent used to prepareextract; type of test (in vitro, in vivo, human study);test species (e.g., rodent, primate) and status; doseand route of administration.

Other information: References to compounds that havebeen partially or completely synthesized; studies ofcultivation; effects of cultivation, processing, andstorage on yield of useful active constituents.


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42 ● p/ants : The Potent/a/s for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

biological activity, it would be cost-ineffectivenot to carry out as many bioassays as possible.Routine techniques are available for isolationand purification of active principles after bio-assay-directed plant fractionation to enrich thebiological activity; however, most existing com-pounds could not be separated economicallyfrom plants using the more sophisticated pro-cedures. Efforts should be made to use simpli-fied procedures so that high extraction costsdo not prevent commercial development. Clin-ical evaluation is expensive and complicated,requiring evaluation at several stages by FDA.The estimated total cost for developing a newdrug depends on the costs for clinical testing,but would fall between $5 million and $35 mil-lion.

Ten computerized online data bases have in-formation useful to a plant-derived drug devel-opment program (table 3). All but one are un-able to compare, correlate, or analyze researchdata analytically; they are solely bibliograph-ic. Ideally, one would desire a nonbibliographicfile that could list and, by computer, compareor correlate real data contained in pertinent

citations, then present the data in a digestibletabular form providing the citation sources. In1975, NAPRALERT (Natural Products Alert)was initiated to overcome the difficulties inusing existing files for developing researchprojects associated with natural products anddrug development.

Approximately one-third of the citations nowcomputerized in NAPRALERT represent ret-rospective searches of literature from the early1900’s to the present. The remainder cover cur-rent information. In addition to bibliographicinformation, NAPRALERT records the chem-ical constituents and pharmacological bioassayinformation from plant, microbial, and animalextracts. The accepted and synonymous no-menclature of the organism, the parts of theorganism used in the study, and the geographicsource of the material are important elementsof the data base. NAPRALERT also recordsethnomedical or folkloric notes as they are en-countered in the literature.

This data base can be used to systematizerandom screening of plants through organizedcomputer search and analysis of data to pro-

Table 3.—Data Bases Pertinent to Drug Development

Name Developer Contents

Agricola

BIOSISPREVIEWS

CAB

FSTA

CACON

MEDLINE

IMEPLAM

—

USDA

BiosciencesInformationServices

CommonwealthAgricultural Bureauof EnglandFood Sciences andTechnologyAbstract

Cacon ChemicalAbstractsCondensate

National Library ofMedicineMexican Institutefor the Study ofMedicinal PlantsChinese University

Agricultural chemistry and engineering, food and plant science, nutrition and related agri-cultural fields

Life science for microbiology, plant and animal sciences, experimental medicines, agri-culture, ecology, pharmacology, biochemistry, biophysics

Compilation of 20 agricultural science data bases; includes plant and animal breedingabstracts, plant pathology, nutrition, entomology, related fields

Agricultural chemistry, food science, home economics, patents

Most life sciences and physical sciences

Life sciences and/or medical information

Natural history and folkloric claims for Mexican plants

Retrospective and current literature citations and brief abstracts of Chinese publicationsof Hong Kong on traditional medical practices

NAPRALERT University of Illinois Bibliographic information; chemical constituents; pharmacological bioassay information;plant names, parts and geographic source; ethnomedical information



vide a ranked list of the more probable can-didates for study. Such a method usingNAPRALERT was tested for a WHO TaskForce assembled to identify indigenous plantspotentially useful for human fertility regula-tion, identifying approximately 4,500 plantsbased on folkloric claims or laboratory ex-periments. Three hundred were identified asmost promising for study through folklore in-formation, pharmacological, and geographicdata. Fifty have received preliminary labora-tory investigation, and eight have confirmedactivity but have not undergone clinical testingyet.

NAPRALERT has the capability to presentin one computerized report all published in-formation on folklore uses, biological activities(in vitro, in animals or humans), and chemicalconstituents. Together these data may suggestareas for research on new uses or applicationsof a specified plant or group of plants. They

can also be used effectively to assess potentialdangers or to suggest safeguards that shouldbe employed when using certain plants.

While plants already are important ingredi-ents of U.S. pharmaceuticals, they could bepotential sources of many new chemicals forthe drug industry. Despite this potential, phar-maceutical companies have discontinuedplant-drug development programs. One reasonthey give for their disinterest is the high costof developing a new drug. Any means of system-atizing plant selection for screening by mak-ing data on past research and folklore use read-ily available would decrease research time andimprove the chances of discovering a market-able drug. Ten automated data bases exist thatcan provide such information useful to drugdevelopment programs. NAPRALERT is theonly nonbibliographic file and represents aunique data retrieval system of great potentialvalue to drug development work.

USDA'S DATA BASE ON MINOR ECONOMIC P L A N T S

The world has thousands of minor economicplant species which potentially are as impor-tant ecologically and economically as the doz-en major agricultural species. There is an over-whelming number of climatological, pedolog-ical, anthropological, latitudinal, and biologi-cal variables associated with these minor spe-cies. The Economic Botany Laboratory (EBL)of USDA is trying to gather such data on thesepotentially useful species.

Seven data base files and their subsets areor have been online, and three prototype fileshave been developed. The online files can belinked to each other through scientific namesto provide more complete information of spe-cies’ characteristics. But funding has declinedfor this service in recent years; some files havebeen taken offline and others have ceased togrow with increases in available information.

Data Base Files

Ecosystematic File incorporates data fromover 1,000 questionnaires mailed worldwide toscientists and extension people, intentionallyemphasizing developing countries. Within 2years some 500 people responded, sending pub-lished and unpublished ecosystematic data (an-nual rainfall, annual temperature, soil type, soilpH, elevation, etc.) on 1,000 species of econom-ic plants, weeds, and nitrogen-fixing species.Each species in the file is recorded with thename and address of the reporting scientist(s),thus providing opportunities for more specificfollowup.

Yield File includes data from the question-naires and from publications of experiment sta-tions. The entries probably account for lessthan 1 percent of the yield data published an-

44 . Plants: The Potentials for Extracting Protein, Medicines, and Other Useful Chemicals—Workshop Proceedings

nually by experiment stations. With increasedfunding, the data in this file could be increased,thus providing a means to compare yields ofexotic crops (with various inputs) in ecological-ly similar areas.

Climate File includes monthly temperatureand rainfall means for about 20,000 stationsworldwide and the elevation of most of theselocalities. This file is the computer tape ofWernstedt’s World Climatic Data, supple-mented by information from publications andthe questionnaire sent out by USDA. A conti-nentality variable that compensates for season-al temperature extremes of continental siteshas been added to the file. This helps differen-tiate among climates with similar mean annualtemperatures but different vegetational poten-tial. A species’ ecological amplitude can bedetermined by using this file in conjunctionwith ecological data for geographical areasfrom which the species is reported.

Where no data on climate are available, thepresence of weed or plants with known eco-logical amplitudes of temperatures and rain-fall can help predict climate in remote areas.Data on weeds’ climatic amplitudes wereadded to this file under the Ecological Ampli-tudes of Weeds program. Another use of theEcological Amplitudes of Weeds program is inmapping the potential for an alien weed tospread in the United States. Climates favorableto the spread of a weed can be located by de-termining ecological amplitudes of a weedthrough consulting its distribution and extract-ing climatic data from the Climate File.

EBL has formulas for converting its 20,000climatic data sites into Holdridge life-zonemaps for countries not now mapped in theHoldridge system. Standing biomass, total car-bon, and annual productivity of the zonal for-ests can be projected from this information,giving real or projected yield figures for high-biomass grasses, energy-tree plantations, orconventional crops. This could provide someguidelines for choosing the best crop-agrofor-estry combinations for agricultural develop-ment in Third World countries.

Nutrition File includes at least one credibleentry for each plant species in Food Composi-tion Tables for East Asia, Africa, and LatinAmerica. The plant’s nutritive contents (ele-ments, vitamins, calorie, and fiber content) areranked extremely low, low, high, or very highrelative to USDA’s recommended dietary al-lowance (RDA). The Nutrition File (as-pur-chased proximate analysis or zero-moistureanalysis) can be linked through a species’ scien-tific name to the Yield File to convert yieldsof grain per hectare to yields of protein per hec-tare, and to the Ecosystematic File to showwhich will yield the most leaf protein per hec-tare under any specified combination of annualtemperature, annual precipitation, soil pH, etc.

Ethnomed File was compiled to encourageThird World countries to supply medicinal andpoisonous plants for a collaborative screeningprogram with the U.S. National Cancer Insti-tute. With 88,000 entries, the Ethnomed Fileis probably the largest extant computerizeddata base for folk cancer remedies. The file alsocovers general folk remedies and pesticidal ac-tivities. Ethnomed no longer is online but sur-vives as a much consulted printout.

Prototype Data Bases

Agroforestry File includes different subfilescontaining information on ecological parame-ters, germination requirements, nutrition val-ues, cultural requirements, yields, wood char-acteristics, use, and plant pathology for severalspecies considered for agroforestry. Perhapsthe prototype file’s greatest impact was to showthat almost no data were available on most non-conventional economic plants.

Pest file has only about 2,500 entries listingthe scientific name of the host plant, the plantpart affected by the disease of insect, and thename and type of pest. Although this informa-tion is useful for predicting pest problems ifthe pest is known to be in the area chosen forintroduction, it does not help predict the pos-sible presence of the pest on the site. If the filewere expanded to provide data on the ecolog-

Ill.—Summary and Discussion of Each Workshop Paper Ž 45

ical amplitudes of pests and diseases, it couldhelp avoid or reduce the risk from pathogensor pests. This could launch a new phase in bio-logical control of pests’ “biological evasion.”For example, where the host tolerated morecold than the pests, planting in the colder areamight be advantageous.

Intercropping lists major and minor cropcombinations, all species in pasture mixes,yield data, yield differentials, and cultural andother variables. By using the scientific namesto link this and other files one could find outwhich crops have been tried around the worldas intercrops. In densely populated ThirdWorld areas, intercropping clearly promisesmore quality, quantity, and/or variety of cropsper hectare than monocropping.

Limitations to the application of the EBL datacompilation program exist. In intermediateecotypes, the effects of factors such as slope,soil porosity, soil type, vegetation cover, cul-tural conditions, insolation, prevailing winds,etc., on plant characteristics maybe significant.Few data are available and some of thesevariables are entered for only a few places. The20,000 sites for which there is climatic data arenot classified under a single soil-classificationsystem. This prevents correlation of plants’ecological tolerances based on soil properties.

A major program would be needed to collatethe Food and Agriculture Organization and/orUSDA soil units with the 20,000 climatic datasites, soil pH, weeds, crops, yields, diseases,insect pests, and native perennials. This couldbe done for a large number of the 20,000 sites.This “International Plant Utilization DataBase” would develop ecological amplitudesand means and determine optimal conditionsfor all the economic species of the world andtheir pests and pathogens. Ancillary to thiscould be the development of an economic database that includes transportation costs, shelflife, world demand, trends in production, andcurrent price of a species. Crops that make the

most sense economically then could be chosenfrom the many crops ecologically adapted tothe area. Experimental data resulting fromtrials would be used to select the right speciesfor that particular area and to augment and re-fine the data base. This capability of matchingcrops to their most suitable environment wouldbe extremely valuable for use in both theUnited States and in developing countries. Itwould assist significantly in agricultural plan-ning programs sponsored by international de-velopment agencies by suggesting best crop op-tions for target environments. Use of the EBLdata base could minimize crop-development ef-forts in environments that are marginal or un-suited to the crop species and help avoid orreduce the use of costly or ecologically disrup-tive agricultural inputs (e.g., energy, water,agricultural chemicals). In addition, it couldhelp reduce the risk of spread of disease andpests.

Such a data base could select species bestadapted to a given climate for whole-plant util-ization schemes in which food, oilseeds, leaf-proteins, chemurgics, drugs, etc., would be themain products and biomass would be an en-ergy-producing or commercial fiber byproduct.Greater plant use becomes more important aspetroleum supplies—for energy and for trans-portation of products—become more scarceand expensive.

Without renewed funding these data baseshave a short life expectancy. The cost of main-taining the files online is at least $10,000 a yearbefore any programs are run on the data.USDA is a constant user; daily, scientists con-sult the hard copy generated by the EBL database to answer questions on agronomy, agro-forestry, climate, ecology, ethnomedicine, nu-trition, pathology, and utilization. Many otherU.S. Government agencies have benefittedfrom the files and could reduce future costs byconsulting them.

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