BotanyAn Introduction to

Pharmacognosy

Pharmacognosy deals with:• The plants and animals that yield drug substances.• 2-The chemical, physical and biological properties of

the substances.• 3- The methods employed in harvesting the crude

drugs.• 4- The methods employed in processing and storing

crude drugs.• 5- The methods used for extraction and preparation

of their active constituents.• 6- The knowledge of the medicinal uses of the crude

drugs.

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3-4-5-

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For detailed description of drugs, the following parameters should be fulfilled:

• the biological and geographical sources,• a short note on the history • and the name of the drug.

• cultivation of the plant, • collection of the part used, • drying, • packing • and other treatments of the drugs during its course from

the biological source to market.

1- Origin:

2- Cultivation and preparation:

• Including the macro- and microscopical characters.

• • The chemical identification of the drug.

3- Characters:

4- Constituents

5- Chemical tests

6- Adulteration and/or substitution

7- Isolation and purification of the active constituents

8- Uses of the drug in folk medicine and therapy

Crude drug = Raw Drug• It is the harvested and usually the dried plant or

animal sources of pharmaceutically or medicinally useful products before they have undergone extensive processing or modification.

• It is a part of plant or animal, which has been, or still, used in medicine or such products of these vegetable parts which have been extracted but not used by it.

Crude Drugs

• Entire plants or animals i.e Lobelia, Mentha, Cantharidis, Cochineal.

• Entire members of plants or animals i.e Clove and thyroid gland.

• Minerals i.e. Chalk, Kaolin and Talc.

• Substances derived from plants or animals i.e. Opium, Aloes, Tragacanth, Resins, Musk, Beeswax and Gelatin.

Examples of Crude Drugs:

• Fibres and Fabrics used for making surgical dressings

• i.e Materials used as strainers for filteration or for clarifying cloudy liquids, “Filteration Material” e.g. Diatomite and Asbestos, also substances as Agar, Gelatin and Wax.

• Materials used for destruction of insect pests “Insecticides and Pesticides” i.e Derris and Pyrethrum.

• 1- Identification of the source of the materials forming a drug.

• 2- Determination of its morphological characters.• 3- Investigation of the potency of the drug, purity and

freedom from admixture.• 4- Planning the proper methods of cultivation of the

medicinal plants yielding these drugs.• 5- Prescription of details of processes of collection

and preparation.• 6- Detailed knowledge of the constituents of drugs

and investigation of their chemical nature and various reactions.

Functions of a pharmacognosist

Classification of Crude drugs

Vegetable drugs are usually arranged for study in one or other of the following ways:

1- Alphabetical:

using either Latin or English names; the drugs are arranged in an alphabetical order.

2- Taxonomic:

using one of the accepted systems of botanical classification; the drugs are according to the plants from which they are obtained in phyla, orders, families. Genera and species.

• 3- Morphological: • dividing the drugs into groups e.g. leaves,

flowers, fruits, seeds,..... which are referred to as “Organized drugs", and groups as dried lattices, extracts, gums, resins, oils, fats and waxes which are known as “Unorganized drugs".

• 4- Chemical: • the drugs are divided into groups according to

their most important constituents.• e.g. drugs containing volatile oils, glycosides,

alkaloids, bitter principles, tannins, saponins,......

5- Pharmacological and therapeutic effects: • grouping of drugs according to the

pharmacological action of their most important constituents or their therapeutic use.

• e.g. astringent, irritant, drugs affecting the gastrointestinal tract, drugs promoting systemic effects on the muscle and nervous system, drugs affecting the circulatory system, drugs used chemotherapeutically for the treatment of infectious diseases, etc....

• Drugs are either official or unofficial.

• An official drug is one which is listed and described in a book recognized by the government as the legal authority for standards “Pharmacopoeia’’.

• The 1st Egyptian Pharmacopeia appeared in English in 1953 and in Arabic in 1961.

Official and unofficial drugs

• There are two origins for each drug; the natural or biological, as well as, the geographical origin.

• The commercial origin is also of interest in case of certain drugs.

Origin of drugs

• It is the plant or animal yielding it, if a plant, botanical origin or botanical source and if an animal, zoological origin or source.

• The knowledge of the biological source enables one to indicate with certainty the proper right material and the precise article one wishes to obtain.

1-The natural or biological origin (source(

• e.g. Strophanthus is used as a heart tonic and includes about 30 species, all species from the same district in central Africa.

• One year, the drug is active, even poisonous and in other cases it is inactive. This is due to the fact that the drug is gathered from any species, which collectors amy find.

• If the drug is obtained from one and the same species the supply of the drug will be always of the same potency.

• So the identification of the exact origin of the drug needs comparison with authentic or genuine samples or identification by comparison with herbarium or referring to gardens or museums.

The binomial system for nomenclature of drugs

• Is due to Swedish biologist Linnaeus, in this system the first name, which is always spelt with Capital letter, denotes the genus.

• whilst the second name denotes the species. It is however, still equally correct to use capital where the species is named after a person.

• Thus the species of Cinchona named after Charles Ledger, who brought its seed from Brazil 1865, is known as Cinchona Ledgeriana.

• It is noted that the pharmacopoeias and research papers, botanical names are followed by names of persons which refer to the botanist who first described the species or variety.

• The specific name is usually chosen to indicate:

1- Some striking characteristics of the plant:

• a- Glycyrrhiza glabra (glabrous = smooth).Refers to the fruit of this species which is a smooth pod.

• b- Atropa belladonna (bella = beautiful, donna = lady) the juice of the berry placed in the eyes causes dilatation of

the pupils, thus giving a striking appearance).

• c- Hyoscyamus muticus (muticus = short). The plant being short.

2- A characteristic colour:a- Piper nigrum (nigrum = black)b- Veratrum viride (viride = green)c- Citrus aurantium (aurantium = golden yellow)d- Digitalis purpurea (purpurea = purple)e- Digitalis lutea (lutea = yellow)

3- An aromatic plant or certain aroma:a- Myritaceae fragrans (having a fragrant, nice aroma)b- Caryophyllus aromaticus (refers to the aroma)

4- Geographical source or history of a drug:• Cannabis indica (growing in India)

5- Pharmaceutical activity or an active constituents:

a- Papaver somniferum (sleep inducing)b- Quillaia saponaria (containing saponins)

6- General meaning or a special indicationa- Allium sativum (= cultivated)b- Triticum vulgaire (= wild)

• It is the region in which the plant or animal yielding the drug grows.

• Knowledge of the geographical source also assists in identification of the biological origin, because it is generally known that plants of certain type come from particular districts and one may often exclude from consideration entire families of plants, as well as, individual species or one may deduce the possibility that the drug may be derived from a plant belonging to one of some few families characteristic of the region.

2- Geographical sources of drugs

• Every climatic region of the earth is the native habitat of some species of animals and plants.

• Drugs are collected in all parts of the world, the Mediterranean region yields more drugs than any region of the world however India, East Indies, Europe, South and Central America yield numerous valuable drugs.

• It is important to note that the habitat affects not only the constituents but also the medicinal value of the natural drug.

• The commercial origin drugs refer to the countries included in their production and/or their channels of trade so such drugs frequently bear a geographical name indicating:

• 1- The country in which they are collected i.e. English Hyoscyamus• 2- The city from which they are shipped

i.e Alexandrian Senna• 3- Indicate a certain veriety i.e Spanish Liquorice

3- Commercial origin

• Production of crude drugs from their medicinal plants involves the following steps:

• I. Cultivation• II. Collection• III. Drying• IV. Packing• V. Preservation and protection

Production of Crude Drugs

• Crude medicinal drugs may be collected from:- Wild growing medicinal plants- Cultivated medicinal plants.

• Plants growing in their native countries are said to be indigenous to these regions,

• e.g. Aconitum napellus of the mountainous regions of Europe,

• Hyoscyamus muticus of Egypt, Cannabis sativa of India.

• Plants are said to be naturalized when they grow in a foreign land or in locality other than their native home.

Cultivation of medicinal plants

Collection of Crude drugs from wild growing medicinal plants has the following disadvantages• 1- Wild medicinal plants found spread in wide

distribution “unlimited areas”.• 2- There is significant difficulty in collection and

transportation because they are mostly growing in deserts and forests far from any means of transport.

• 3- Continuous extensive collection of wild medicinal plants can lead to extinction or serious deficiency of the plant.

• 4- the collected amount of wild medicinal plants may be insufficient for the market needs.

• 5- Adulteration; collection of crude medicinal drugs from wild sources may lead to adulteration that can be attributed to ignorance of collectors who may collect:

• a- The desired plant with others.• b- Undesirable organ of the desired plant.• c- The desired plant at improper time.

Collection of Crude drugs from cultivated growing medicinal plants has the following advantages

• 1- Concentration of a large quantity of the plant of choice in relatively small areas simplifies collection.

• 2- Cultivation provides an excellent mean for control of the purity of the crude drug.

• 3- Cultivation assures regular and constant supply can be sufficient to market needs.

• 4- Cultivation allows producers to apply different methods for improvement of the gained crude drug by controlling certain factors:

• a- Treatment of seeds before sowing to ensure germination and exclusion of defective seeds i.e. soaking Hyoscyamus seeds in dilute sulphuric acid fasten germination.

• b- The use of fertilizers which can provide cultivated plants with certain essential elements as N, K and P which can increase the produced active constituents.

• c- The use of certain insecticides and pesticides help control of insect’s infestations.

The disadvantages of collection of crude drugs from cultivated medicinal plants are:

• 1- The high cost of production when applied on small scale while economic only when carried on large scale.

• 2- Some medicinal plants require particular habitat for their growth and the procedures of their cultivation usually gain failure.

• i.e. Cannabis requires tropical climate production of narcotic resin while Aloes require a heavy rainfall.

• For successive cultivation of medicinal plants and production of crude drugs with quality, it is necessary to study the conditions under which medicinal plants flourish in their wild state and trying to reproduce these conditions or improve them.

Factors affecting plant growth and production of crude drugs

• Classified into:

1- Environmental factors: • Including water, light, temperature, altitude, etc.

2- Soil and soil contents: • Including plant nutrients, macro-elements and micro-

elements, active elements, inactive elements, organic matter and living organisms.

• 3- Growth Regulators.• 4- Genetics and plant tissue culture.

1- Environmental Factors:

• a- Water:• Importance of water:• 1- It is an important component of the cell

which is the building unit for every living creature.

• 2- It is a vital factor in all biological reactions and transformations in living beings, it can act as medium, catalyst, part of the biological reaction or even end product of it.

• b- Temperature:• Temperature divides the world into various zones and

plant growth is greatly affected by temperature.• The effect of temperature on the reaction of the plant

which is finally expressed in its effect on the plant growth as a whole.

• It has a great effect on on seedingi.e as temperature is increased, the rate of growth is

increases until an optimum value is reached, above which further increase in temperature leads to a decrease in growth rate.

• This is due to the fact that chemical reactions, in general, increase in rate as temperature is increased, but as it is still further increased, other reactions, such as heat denaturation and protein inactivation predominates.

• For each plant, growth is designated by three temperatures:

- The minimum temperature- The optimum temperature- The maximum temperature

c- Altitude:• It affects the growth of medicinal plants.• In general, the highest temperature are experienced

near the equator, and temperature falls with elevation• i.e Jamaica to have a tropical climate on the coast and

a temperat one in the mountains so sugar can be cultivated at the coast as it is a lowland plant while Tea can be cultivated at elevations.

• d- Light:• Plants vary in the amount and intensity of the

light which they rquire.

• The effects of light intensities on the growth of plants are related mainly to the role of light in “Photosynthesis”.

• ‘Photoperiodism’: • defined as the response of plants to the length

of day, or correctly, to the relative length of day and night.

Plants classified into three broad photoperiodic classes with respect to their flowering behavior:

• 1- Short-day plants:• These plants flower only when the daily period of illumination

is shorter than a particular critical length i.e. Tobacco.

• 2- Long-day plants:• These plants flower only when the daily period of illumination

exceeds some critical duration i.e. Dill.

• 3- Day-neutral plants:• These plants flower under any of a wide range of day lengths

i.e. Capsicum.

• “Plant nutrients and/or Plant Manures”

• Soil is a mosaic of rock particles, plant roots, micro-organisms, decaying organic matter (humus), aqueous soil solution and interconnecting air passages.

• Soil is a store house of water and minerals required for growth of plants.

• Soil differs from one another both in physical and chemical properties.

2- Soil and soil contents

• “Absolute water capacity”• The amount of water which remains in a soil

after any excess has drained away.

• The air capacity of a soil is inversely proportional to water capacity.

• i.e. Sandy soil are very permeable while clays possess a high power of absorbing water.

Organic Manures• Manure is a mixture of organic matter, which is

composed mainly of plant remains put under animals in the stable and ultimately mixed with the animal urine and other animal excretions and some of the stable soil.

• Importance of manures:• 1- Manures are used as fertilizers.• 2- They block the soil particles together and improve

conditions of growth i.e. organic matter in soil takes up and holds water in the same ways as a sponge holds water.

• 3- Manure is of value as a source of nutrient elements, especially nitrogen.

Essential elements commonly supplied by the soil are divided into 4 groups:

• 1- Main nutrients or Macro-elements:• Involving nitrogen (N), phosphorus (P) and potassium (K).

• Commercial fertilizer containing one of these elements is called a simple fertilizer and if containing all of them, a complete.

• N.B.: • - Deficiency of (N) produces stunted yellow colour (chlorosis).• Deficiency of (P) reduction of plant size and deep green

colour.• Deficiency of (K) reduction of carbohydrate synthesis.

• 2- Active elements:• Involving calcium, magnesium and sulphur.• The little amount of which increases plant

growth, but more than adequate amount has no effect on plant growth.

• 3- Inactive elements:• Involving sodium, aluminum, silicon and

iodine.• They have negligible effect on plant growth.

• 4- Micro-elements:

• Involving iron, boron, copper, manganese, zinc, cobalt, lead and molybdenum.

• These are needed within very minute amounts for plant growth while any rise in this amount has poisonous effect on plants.

3- Plant growth regulators

• Growth and development of plants is regulated by a number of chemical substances, which together exert a complex interaction to meet the needs of the plant.

• Five groups of plant hormones are well established they are:

-Auxins - Gibberellins (GA) -Cytokinins - Abscisic acid and its derivatives - Ethylene

• They are: - specific in their action, - active in very low concentrations• Regulate: - cell enlargement, - cell division, - cell differentiation, - organogenesis, - senescence and dormancy• Some are classified as growth regulators while others as

growth inhibitors.• Growth stimulators: i.e. auxins, gibberellins (GA) and

cytokinins• Growth inhibitors: i.e. abscisic acid and its derivatives

and ethylene

Growth stimulators

• a- Auxins:• The most important natural one is 3- or β-indole

acetic acid (IAA).• Typical effects of auxins are:• 1- Stimulates the growth (cell elongation).• 2- Ovary growth: IAA alone is not always sufficient

to promote fruit growth but GA may be needed. • 3- Cambial activity: the ratio of IAA and GA is

important in determining whether phloem or xylem tissues were formed by the cambium.

• 4- Effects on the formation of secondary metabolites • i.e. seedlings and young plant of Mentha piperita

when treated with IAA, gave in the mature plants an increased yield (30-50%) of oil which itself contained more menthol.

• 5- The main practical uses of auxins are: - Low concentrations accelerate rooting of woody and

herbaceous plants.- Higher concentrations act as selective herbicides or

weed killers.

• b- Gibberellins:• About 40 gibberellins are now known, in higher plants

they are synthesized in leaves and accumulated in immature seeds and fruits.

• They have the following effects:• 1- Induce flowering at earlier stages.• 2- Increase the length of the dwarf varieties of many

plants.• 3- effects on secondary metabolites- Volatile oils in case of Citrus, Mentha and many

umbelliferous fruits, the amounts of volatile oils variably increased

- Alkaloids: Belladonna, Hyoscyamus and Nicotiana produced more alkaloids.

- Glycosides: The total glycosides in Digitalis were increased.

• c- Cytokinins:• It is the cell division hormone.

• Their effects are:• 1- Cell division.• 2- Cell differentiation and morphogenesis (ratio of

cytokinin/auxin).• 3- They have inhibitory effect on senescence.

Growth Inhibitors• a- Abscisic acid:• It is widely distributed in plants.• It acts by antagonizing GA, blocking synthesis of

DNA and enzymes.• It induces seed dormancy and inhibits shoot

growth and helps to withstand draft conditions.• b- Ethylene:• It was demonstrated that ethylene evolved by

stored apples inhibited the growth of potato shoots enclosed with them.

II- Collection of Crude Drugs• Qualitative and quantitative composition of

plants may change greatly during the course of growing season, time of the day and stage of maturity.

• To ensure maximum quality of a crude drug, it must be collected at a proper stage of development.

• The active constituents may be distributed in:• All parts of the plant or • Concentrated in certain organs or• In specific tissues of these organs.

Factors affecting collection of medicinal plants:

• 1- Time of the year:• The active constituents of medicinal plants

vary quantitatively and qualitatively througout the year.

• Examples:• a- Rhubarb contains no anthraquinones in

winter but contains anthranoles, which on arrival of warm weather converted by oxidation to anthraquinones.

• b- Colchicum corms is almost free of bitterness and almost devoid of colchicine in autumn and is full of starch, so it is collected at the end of the autumn and used by the farmers of Austria as food instead of potatoes, but in spring and early summer it is bitter due to high colchicine content and hence should be collected for medicinal use.

• 2- Time of the day:• Affects both the therapeutic value and activity of

medicinal drugs.• It is an important factor in determining the

concentration of active constituents in medicinal drugs.

• Examples:• a- Digitalis leaves collected in the afternoon

contain more glycosides than those collected in the morning.

• i.e the active glycosides undergo hydrolysis to physiologically less active aglycones during the night and recombine with sugars during day-time.

• b- Solanaceous leaves have higher alkaloid content when collected in the morning than those collected in the afternoon.

• 3- Stage of maturity and age of the plant:

• The quality and quantity of the active constituents depend on the stage of maturity and age of the medicinal plants collected.

• Examples:

• a- Santonica flowers are most rich in santonin, when they are unexpanded and when they start to open, the santonin content starts to decrease due to light oxidation to yield inactive photo-santonin.

• b- Solanaceous leaves contain higher alkaloid content when the plant is in the flowering stage.

• Certain Pharmacopeias specify the time and stage of collection of certain important drugs as they should be collected when they are containing the highest amount of active principles and they will have better appearance when dried.

• Example E.P. 1984 specified that: Lobelia herb must be collected towards the end of the flowering stage.

General rules for collecting crude drugs are as follows:

Leaves• They are collected at the beginning of the

flowering stage when they contain the optimum percentage of their active constituents.

• Collection must be done in dry weather as wet weather causes deterioration and discoloration during drying.

• Methods of collection varies according to the medicinal plant:

• Senna leaves: the whole plant is cut and the leaves are picked off after drying in the sun.

• Digitalis leaves: are gathered directly from the plants.

• Coca leaves are gathered directly from the plants when nearly ready to fall from the stem.

Flowers• Collection of flowers must be carried out in fine

dry weather in order to fix the colour of the product.

• Generally flowers are gathered just at the time of pollination and before the formation of fruits.

• Exceptions are:• Cloves and Santonica are collected in bud stage.• Chamomile flower are collected just after full

expansion.

Barks

• It is usually done in the spring or in early summer when the cambium is active and the bark can be easily stripped off from the trunk and branches.

• Longitudinal incisions are made at intervals, round incisions are made of the stem and the bark is stripped off in long pieces.

Fruits

• Fruits are collected near the ripening stage • i.e. when they are fully grown but not

completely ripened.

• Seeds are collected when mature• i.e. they are separated from the pericarp.

Seeds

• Include: Roots, Rhizome, Bulbs and Corms.

• Generally they should be collected in autumn or winter after removal of aerial parts and before the vegetative process starts.

Underground organs

• Include: Resins, Gums, Latex,….etc.• They are usually collected in dry weather.• Unorganized drugs are usually natural

secretions such as beeswax and myrrh or derived from parts of plants or animals by some process as:

• 1- Incision, e.g. Opium and Gum Tragacanth.• 2- Decoction, e.g. Agar and Gum Arabia.• 3- Expression, e.g. Olive oil.

Unorganized drugs

Different methods used for preparation of crude drugs before drying

• After collection of crude drugs, many of them need distinct procedures for preparation before drying.

• i.e. cleaning, grabling, decortication, bleaching and sometimes curing.

• Examples:

• De-cortication of Cinnamon bark • Cinnamon bark present as a very thin bark in small

quills, compound quills showing longitudinal yellow lines marking the pericycle fibers on the outer surface due to removal of the outer layers (cork and cortex).

• The official appearance gained by decortication process, which is done for the following reasons:

• 1- lack or existence of low percentage of active constituents in the outer parts.

• 2- Present of unrequired constituents in the outer tissues

• i.e. bitter substance which alter its sweet taste.

Bleaching of Ginger and Nutmeg:

• Bleacjhing alters the appearance of certain drugs when they are being prepared for the market, i.e. Ginger and Nutmeg.

• Coating with a layer of inert substance such as CaCO3 or CaSO4 for preservation purposes.

• Curing of certain drugs:• It is a process of inducing some desirable

changes in the drug after collection and before drying by enzymatic action.

• Examples:

• Tea Leaves: curing is done to set free soluble caffeine and oxidize tannin into insoluble products.

• Vanilla pods: curing is done to set vanillin free.

III- Drying of Crude Drugs

• Fresh plants usually contain high percentage of moisture (up to 80 or 90 %).

• The duration of drying process varies from few hours to many weeks.

• Importance of drying of crude drugs:• 1- drying stop the enzymatic action that might

change the active constituents, i.e. to fix the active constituents.

• 2- Drying help in avoidance of deterioration of crude drugs upon storage by preventing the growth of micro-organisms (bacteria and fungi).

• 3- Drying of crude drugs facilitate packing and storage and decreases transportation cost as the weight of the drug is greatly reduced.

• 4- Careful drying is also essential to obtain drugs which:

- Retain their physical characters.- Retain their chemical constituents.- Fulfill the Pharmacopoeial requirements for

maximum moisture content.

Factors affecting drying process

Temperature Time

• The duration of drying varies from few hours to several weeks depending on the structure and water content of the drug.

• Drying process should reduce moisture content of the drug below its critical threshold level.

Methods of drying

Natural drying Artificial drying

Sun Drying Shade Drying

Direct fire

Stove

Drying champers

Vacuum drying

Freeze drying" Lypophilization"

1- Natural Drying:• It is the use of climatic heat.

• i.e. -the drug is dried by exposure to direct sun - spreading in the shade by putting on the

floor or mats or trays in a single layer and as drying proceeds drugs are turned over

• Whether the drug is dried in the sun or shade it is protected from moisture and so it is covered at night or in periods of rain.

• Sun drying• Used for those items which are not

affected by direct action sunlight.

• Shade drying• Used when it is desirable to retain the

natural color of the drug and preserve its sensitive active constituents.

• Physical Drying - carried out by the use of elevated

temperature and/or decreased pressure (vacuum) or the use of radiation of infrared or radiofrequency wavelength.

• Chemical Drying - carried out by the use desiccants.

2 - Artificial Drying:

• Drying with artificial heat is generally the most acceptable method when skillfully operated

• The heat should be such as to maintain an efficient temperature for vaporizing the moisture but not high to affect the constituents of the drug.

• And the ventilation such as to efficiently utilize the heat units in the air and then remove the moisture-laden air at the time of saturation.

• When heat and ventilation are properly controlled, the plant material is thoroughly dried and produces a drug of maximum quality both in the constituents and appearance.

Advantages of artificial drying:

• 1- immediately stops enzymatic action

• i.e. in Digitalis leaves the natural moisture content of the leaf is sufficient to cause an enzymatic hydrolysis of the cardiac glycosides as soon as the leaf is harvested, if the leaves are allowed to dry naturally, a very rapid hydrolysis if these glycosides occur.

• 2- is a rapid method, usually done at a well controlled temperature.

• i.e. rapid drying, not only prevents the decomposition of active principles but also retains the color of the drug.

Artificial heat may be applied by:• 1- Direct fire.

• 2- Use of heated stones.

• 3- Use of stoves, these must be done carefully to prevent the damage produced to drugs when dried i.e. burning.

• 4- Drying sheds or chambers.

• 5- Drying ovens.

• 6- Pneumatic high speed drying is applied for sensitive drugs.

• i.e. Digitalis. The drug is dried by exposure to high temperature (800°C) for a fraction of a second under reduced pressure.

• 7- Freeze Drying (Lypophilization)• It is an extreme form of vacuum drying, in which

the water is frozen and drying takes place by subliming the solidified ice-phase where very low temperature and high vacuum are used.

Precautions for drying different plant organs:

• 1- Leaves: • must be dried as quickly as possible to retain their

fresh green color and prevent decomposing of their active constituents.

• i.e. Digitalis leaves must be dried rapidly in vacuum ovens at 60°C.

• 2- Flowers:• must be dried rapidly at low temperature in shade

or in drying chambers to retain their colour.

• 3- Fruits and seeds• are spread on trays and dried in sun or shade.

• 4- Barks, large roots and rhizomes• Dried in the sun and rhizomes are generally

sliced transversely or longitudinally to facilitate drying.

Changes encountered in crude drugs during drying:

• 1- Size and weight• due to loss of water where drugs get smaller in

size and lose 80 – 90 % of their original weight.

• 2- Shape and appearance• Some drugs shrivel and shrink when dried and

the surface get wrinkled or reticulated.• i.e. Black pepper on drying shows polygonal

reticulations.

• 3- Texture:• Fresh organs are generally firm on drying, drug

become harder.• i.e. leaves brittle and horny for drugs containing

starch “gelatinization”.

• 4- Color:• On drying the drug becomes darker in color but in

certain cases a total change may occur.• i.e. Tea leaves change from green to dark brown

almost black.

• The green color of certain drugs changes to brown on drying due to decomposition of chlorophyll either by the influence of the acidic sap or of heat and oxygen.

• 5- Odour:• In certain drugs drying changes the natural odour.• i.e. Digitalis and Hyoscyamus loose their bad

odours when dried while vanilla pods are odourless when fresh and on drying acquire a fragrant, pleasant, aromatic odor due to the liberation of vanillin which has a nice aroma.

• 6- Taste:• The taste of the drug may be altered.• Gentian is very bitter when fresh and becomes

pleasant on drying.

• 7- Constituents:• Constituents of some drugs may change due to

drying.• i.e. fresh vanilla pods contain the glycosides

gluco-vanillin and gluco-vanillic alcohol on drying hydrolysis of both glycosides and oxidation of acid to vanillin occurs.

IV- Packing of Crude drugs

• Importance of packing of crude drugs:• 1- Packing provides protection against dust,

micro-organism and insects attack.

• 2- Packing is economic as it reduces the space required during storage and shipment.

• Effect of packing on appearance:• The various ways of packing usually affect the appearance

of the drug.• i.e. Indian Senna leaves are packed into large bales, using

hyraulic pressure resulting in the leaves being flatter and showing faint oblique or transverse markings where the midribs and margins of their leaves have been impressed.

• Packing also may give indication to the geographical source and port of transport of the drug.

• i.e. Opium, which is the dried latex from the unripe capsules of Papaver somniferum L. Opium is collected principally in Turkey, Yugoslavia, India and China by incising the capsules in various ways and using various instruments.

• Turkish opium occurs in sub-cylindrical cakes about 9 cm high and 14 cm in diameter coated with coarsely powdered poppy leaves, giving them a greenish motted appearance.

• Indian opium is imported in 5 kg blocks wrapped in 2 sheets of thin grease proof paper and tied with tape and placed in polyethylene bags.

• Persian Opium occurs in brick shaped cakes, each wrapped in red paper sometimes in form conical masses and short sticks.

V- Preservation and protection of crude drugs

• Crude drugs are subjected to many hazards at all stages in their path from the living plant or animal to their ultimate use in pharmacy.

• Storage represents the last stage in in the handling of crude drugs before being used and it is a most important stage.

• Drugs usually deteriorate either slowly or rapidly in the time of storage with few exceptions such as Cascara and Frangula barks which shouldn’t be used except after a certain period of time.

• Certain Pharmacopoeias give well, clear instructions concerning time of storage, after which drugs shouldn’t be used.

• i.e. Digitalis, Ergot and Cannabis for their active constituents decompose and they get less active.

• The general undesirable changes which may occur on storage are:

• a- Aromatic drugs usually lose their aroma.• b- Drugs containing fixed oils may be rancid.• c- Volatile oils may be thickened and resinified.

• d- Examples: - Digitalis leaves may lose their activity. - Ergot may acquire a dis-agreable odor.

For these reasons, Pharmacopoeias clear instruction for storage of crude drugs, they must be stored:

• 1- In well closed containers.

• 2- Protected from light, moisture and dust.

• 3- At low temperature.

• 4- Protected from insect infestation.

The principle factors responsible for deterioration of crude drugs may be

Physico-chemical Factors Biological Factors

a- Moisture

b- Light

c- Temperature

d- Air

a- Bacteria & fungi

b- Mites and Nematodes

c- Insects

d- Rodents

1- Physicochemical factorsa- Moisture

• Dried drugs stored in the usual containers reabsorb about 10 % or more of moisture and are termed air dried.

• Moisture may cause:• 1- Hydrolysis of active constituents by

enzymes.• 2- Growth and nourishment of bacteria and

fungi.

To overcome the effect of hydrolysis stabilization of the drug may be carried:

• a- Temporary stabilization:• Can be done by enclosing dehydrating agent

as lime or calcium chloride in the container of the stored drug.

• b- Complete stabilization:• Can be done by destroying enzymes.• Subjecting the fresh drug to alcohol vapors or

immersing them in alcohol.

b- Light:• Any reaction needs a certain energy level which may

be provided by light radiation leading to photochemical reactions.

• Light may affect delicate drugs having color. i.e. - Rose petals are red when fresh and changing to

brown on exposure to light.- Digitalis leaves lose its activity more rapidly in sun

light.- To avoid the these effects of light, stored in the dark

or by the use of opaque or amber colored glass containers.

c- Temperature:• The rates of biological processes are accelerated

by raising the temperature.

• A slight raise in temperature above the normal will activate the enzymatic action or include molecular rearrangements.

• Drugs directly affected with the rise in temperature are those containing volatile oil such as clove and chamomile.

d- Air:

• Oxygen of air has a definite oxidation effect on the active constituents of some drugs leading to lowering the quality of the product.

• In some cases oxidative changes are required to produce the required active constituents, i.e. Frangula bark.

2- Biological Factors:a- Bacteria and fungi

• Sufficient moisture content is essential for bacterial or fungal infestation.

• Fungi usually attack drugs rich in nutritive substances such as roots and rhizomes if they are not stored properly.

• Bacterial and fungal infestation may change the physical properties of the drug such as color and texture.

• The presence of fungi is indicated by their hyphae.

b- Mites and Nematodes:

• Mites belong to the spider group.• recognized under the microscope by having

four pairs of legs and oval body.• They are visible by the naked eye.• Nematodes belong to the group of round

worms.• Mite sand Nematodes may attack the wheat

flour and belladonna stems.

c- Insects:• The dried drugs and their powder form are

susceptible to attack by insects which render them unstable for preparation of standard extracts.

• Insects should be destroyed before storage of drugs by one of the following methods:

• 1- Heat treatment• 2-Fumigation• 3- Liming• 4- Freezing

• 1- Heat treatment:• is done by exposing crude drugs to

temperature 60-65 °C which can kill the insects as well as their eggs.

• Disadvantages:• - not suitable for thermo-labile constituents.• i.e. if heating affects the active constituents of

the drug.

• 2- Fumigation:• Includes use of volatile insecticides in closed

areas such as carbon disulphide.

• Disadvantages:• Has to be repeated at intervals is its dose isn’t

sufficient to kill eggs.

• 3- Liming:• Done by dipping the crude drug in freshly

slacked lime or sprinkled with quick lime which will block the respiratory system of insects and larvae.

• Liming is used with few drugs as Ginger and Nutmeg.

• 4- Freezing:• By subjecting the drug in refrigerator.

d- Rodents:• Rodents are rats and mice can attack crude

drugs during storage if they are stored in paper, cloth, card-board or wooden containers.

• Rodents attack can be prevented by storing in glass, plastic or metal containers and/or the use of rodenticides (e.g. alpha-naphthyl-thiourea).

Chemistry of Crude Drugs

Food Storage Products(Primary Metabolites)

By-Products of Metabolism(Secondary Metabolites)

a- starchb- Amino acids & Proteinsc- Fixed oils & Fats

a- Crystalsb- Gums, Mucilages & Pectinsc- Tannins & tannin containing drugsd- Volatile Oilse- Alkaloidsf- Glycosides

1- Primary Metabolites:a- Starch:

• Starch is the most important carbohydrate present in the plant cell.

• It is formed by accumulation of glucose molecules formed during photosynthesis.

• It is a polysaccharide of glucose units with the general formula (C6H10O5)n.

• Starch consists of two molecules:• 1- Amylopectin (80%): is a branched sugar

insoluble in water.• 2- Amylose (20%): is a linear chain of glucose units

soluble in water

• Special chemical test for Starch: Starch suspension + dilute iodine solution

Blue color

• Uses of Starch:• 1- Dusting powder due to its absorbent

properties.• 2- Skin emollient (in mucilage forms).• 3- Antidote for Iodine poisoning.• 4- Suspending agent and tablet disintegrants.

Some starches of commerce

b- Proteins:• are complex nitrogenous compounds of high

molecular weight.

• Chemically: polypeptides of amino acids.• i.e. mixtures of amino acid units joined

together by peptide linkages through elimination of water.

• Stored by the plants usually in the form of amorphous masses or small paricles called Aleurone grains.

• Microscopical chemical tests for proteins:

• 1- Millon’s reagent

stains proteins red on warming• 2- Picric acid

stains proteins yellow• 3- Iodine solution

satins proteins yellowish brown

c- Fixed oils and Fats• Esters of long chain fatty acids of high molecular

weight.• i.e. Stearic and Oleic acids and glycerol.

• Being either solids or liquids depends on the proportion of esters of saturated (solid i.e.Stearic acid) or unsaturated (liquid i.e Oleic acid) fatty acids.

• In plants they are abundant in fruits and seeds

Characters of fixed oils and Fats• 1- lighter than water, - greasy in touch - leave permanent stains on paper.• 2- Insoluble in water and alcohols except

castor oil (soluble in alcohol).• 3- Soluble in ether, chloroform and petroleum

ether.• 4- Stain red with Sudan III.

• 5- Easily saponified by aqueous solution of KOH yielding glycerol and salt of acids (soaps).

• 6- Fixed oils are liquids at normal temperature (glycerides of unsaturated fatty acid).

• 7- Fats are solids or semisolid glycerides of saturated fatty acids.

• Uses of Fixed oils and Fats:• 1- Nutritive use.

• 2- Pharmaceutically as solvents in intramuscular injections.

• 3- Preparation of soaps, Liniments, Plasters.

• 4- Laxatives, Demulcents and emolients.

2- Secondary Metabolites:a- Crystals

• i- Calcium oxalate:

- produced in plant tissues as detoxifying products for the toxic by product oxalic acid.

- exhibit certain diagnostic shapes which can be considered as key elements for the natural drugs containing them.

Forms of Calcium oxalate Crystalsa- Prisms: - Quillaia bark, - Hyoscyamus leaf, - Liquorice

• b- Cluster: - Rhubarb - Stramonium - Clove• c- Rosette: - Aleurone grains of Umbelliferae.• d- Acicular or Needle-shaped crystals (raphides) - Squill• e- Micro-crystals or sandy crystals - Belladonna leaf (microsphenoidal)- Cinchona bark (microprismatic)

• Special Arrangement of Calcium oxalate:

• Crystal sheath:- Group of fibers ensheathed with parenchyma

membrane, each cell containing one calcium oxalate prism. i.e. Liquorice.

• Crystal layer:• Group of parenchyma cells, each cell containing

calcium oxalate cluster.• i.e. Stramonium

ii- Calcium carbonate:

- embedded in or incrusted in the cell wall in the form of concentrations found on outgrowths of the cell wall and termed cystoliths.

- i.e. Cannabis- Special chemical tests:- CaCO3 dissolves with effervescence in dilute

acids. - i.e. dil. HCl

iii- Hisperidin and Diosmin:

• Crystalline masses of diosmin are present in the epidermal cells of buchu leaves.

• These crystals are insoluble in organic solvents but soluble in KOH.

• iv- Silica:• Occurs as incrustation on cell walls or masses in the

interior of cells.

• i.e. Silica nodules can be found in the sclerenchyma layer of cardamom seeds.

b- Tannins:

• Phenolic substances present in the plants.

• Able to combine with protein of the animal hides, prevent their putrification and convert them to leather.

• Are high molecular weight compounds.

• Many of them are glycosides

• Have astringent effect

• Tannins are classified into two main groups:

• a- Hydrolysable tannins (Pyrogallol tannins)• i.e. tannins in galls, Cloves, Pomegranate.

• b- Condensed tannins (Catechol tannins)• i.e. tannins in Cinnamon, Cinchona, Tea.

• Special chemical test:• Hydrolysable tannins bluish black• Condensed tannins greenish black

FeCl3

FeCl3

c- Volatile Oils:• constitutes the most important odorous

principles in various parts of the plant.• They are secreted with several secretory

structures, i.e. Cells , glands, ducts, hairs which give red color with Sudan III.

• Insoluble in water.• Soluble in alcohol.• Can be stem distilled without decomposition.• Chemically they are mixtures of hydrocarbons

and oxygenated compounds.

• Volatile oils are mostly used as flavoring agents, in perfumery and carminative while some volatile oils have therapeutic uses as:

a- Volatile oil of Buchu (urinary tract antiseptic).

b- Volatile oil in Chenopodium (anthelmintic).

c- Volatile oil in Eucalyptus (anti-rheumatic).

d- Alkaloids:• are organic nitrogenous substances basic

compounds.• Derived from natural origin.• Have marked physiological activities.• Are bitter crystalline substances, but some are

liquids. i.e. Nicotine in tobacco Coniine in Hemlock• Have different structural formulae according to

the nature of the basic chemical structures (i.e. non-heterocyclic structure).

• Chemical classification of alkaloids:• 1- Phenyl ethylaminei.e. Ephedrine (Sympathomimetic).• 2- Tropanei.e. Atropine (Para-sympathomimetic).• 3- Phenantherinei.e. Morphine (narcotic analgesic).• 4- Quinolinei.e. Quinine (anti-malarial).• 5- Indolei.e. Ergotamine• 6- Purinei.e. Caffeine (CNS stimulant).

• Chemical tests for Alkaloids:

• Most alkaloids are precipitated by the following reagents:

• 1- Mayer’s reagent (potassium mercuric iodide).

• 2- Wagner’s reagent (iodine/potassium iodide)

• 3- Dragendorf’s reagent

e- Glycosides:• are non-reducing substances.• Bitter tasted solids.• Soluble in water and alcohol.

Hydrolysis

By acids or enzymes

Aglycone(non-reducing character)

Glycone (sugar)(reducing character)

Glycosides

• Classification of Glycosides:1- Phenolic Glycosides:

i.e.a- Hydroquinone glycosides

b- Flavonoids (flavus means yellow colored)

c- Anthraquinone glycosides

d- Coumarin glycosides

hydrolysisPhenolic aglycone + different sugars

2- Cardiac glycosides• Chemically:

steroidal aglycones

+ unsaturated lactone ring + 2-deoxy sugars

O

R1

OH

R2

O O

3

1912

14

23

17

16

18

OOOO

OOO

H3CH3C

H3COH

HOHO

OH O OH OHCH3

O

14

14

34

• Uses: - heart tonics (cardiotonics). - treatment of auricular fibrillation - treatment of cardiac arrhythmia.

• Cardiac glycosides are two types:• a- Cardienolides (contain 5-membered lactone

ring).• b- Bufadienolides (contain 6-membered lactone

ring).

• Chemical tests of cardiac glycosides:

1- Baljet’s test2- Kedde’s test for lactone ring

3- Liberman’s-Burchard test

for steroidal ring

4- Keller-Killiani test

for Deoxy-sugar

3- Saponin Glycosides• produce permanent froth in aqueous solutions.• have hemolytic properties (i.e. cause blood

hemolysis).

• Classified according to the sapogenin obtained:• a. Steroidal Saponins (C27) i.e. Dioscorea, Digitalis• b. Triterpenoid Saponins (C30) i.e. Quillaia, Ginseng

Sapogenin + suagrs (aglycone)Saponins

hydrolysis

4- Cyanogentic Glycosides

• yield HCN (hydrogen cyanide) as one of the products of hydrolysis.

• can be detected in plants by the HCN reaction with sodium picrate paper (yellow)

red color due to the formation of sodium iso-purpurate

i.e. Linamarin in Linseed.

5- Thioglycosides or Sulphated or Thiocyanate Glycosides

• yield allyl isothiocyanate as one of the hydrolytic products.

• used as condiments and counter irritant

• i.e. Sinirgin in Black mustard. Sinalbin in White mustard.

Adulteration of Natural Products• Adulteration occurs when the drug is: - scarce - expensiveTypes of adulteration:1- Sophistication (True adulteration).2- Substitution 3- Admixture4- Inferiority 5- Deterioration or spoilage6- Addition of worthless heavy materials.7- the presence of adventitious materials within the drug.8- Addition of waste products of suitable color or density

to the powdered drug.

1- Sophistication or True adulteration:• The addition of spurious or an inferior

material to any article with intends to defraud.• Examples:• Addition of wheat flour to powdered ginger

with enough capsicum to restore or enhance the pungency and enough curcuma to maintain the color.

• Small masses of flour dough molded to the correct size and shape of ergot, and colored by dipping first in red ink and then writing ink.

• Nutmeg has been imitated by cutting pieces of basswood to the required shape or by molding a mixture of clay and leguminous meal.

• Coffee has been imitated by compressing powdered chicory to the shape of coffee beans.

• Pieces of string dipped in red ink have been substituted for Saffron or addition of safflower (American saffron).

2- Substitution:• Replacement of the original drug by the

adulterant, i.e. an entirely different article used.

• Different ways of substitution:a- Substitution by inferior commercial varietiesExamples: - Capsicum minimum fruits and chilies C.annum

fruits.- Safflower for safron.

• b- Substitution by exhausted drugs• Examples:• Preparation of volatile oils from cloves or from

umbelliferous fruits such as fennel and caraway, the ungrounded drug is used and the dried exhausted material closely resembles the genuine drug.

• Coloring matter of saffron and red rose petals when removed during exhaustion, the residue is colored by artificial dyes as is done with.

• c- Substitution by superficially similar but cheaper natural substances which usually having no relation to genuine drugs.

• Examples:• Peach Kernels and Apricot kernels for

Almonds.

• Clove stalks and mother cloves are mixed with cloves.

3- Admixture

• It is the addition of one article to another through accident, ignorance or carelessness but if that addition has been done intentionally to defraud, it is sophistication.

• Admixture may occur through faulty collectioni.e. collecting the drug not at the proper time,

collection of other parts of the same plant, collection from other plans by mistake or ignorance of collectors (Argel instead of Senna).

4- Deterioration• It is the impairment of the quality of the drug by the

abstraction or destruction of valuable constituents by distillation, extraction, aging, moisture, heat, fungi and/or insects.

• Examples:• Powdered Squill hardened through absorption of

moisture.• Coffee which lost its caffiene through over roasting.• Ergot which is moldy.• Rhubarb that has become wormy.

5- Spoilage

• It is a form of deterioration in which the quality or value or usefulness of an article is impaired or destroyed by the action of fungi as to render the drug unfit for human consumption.

6- Inferiority

• Can be defined as any substandard condition for any cause.

• Examples:• The dried seeds of Nux vomica, containing less

than 1.15 % strychnine would be inferior or substandard drug.

• Addition of synthetic material to fortify inferior products such as adding citral to lemon.

• Addition of benzyl benzoate to balsam of Peru is considered an adulteration.

7- Addition of worthless heavy material

• Addition of large masses of stones in liquorice bales.

• Addition of lead shots in pieces of Opium.• Addition of mineral, vegetable oils, glycerin or

ammonium nitrate to saffron.

• 8- the presence of adventitious matter naturally with the drug.

9- Addition of waste products of suitable color or density to powdered drugs

• Examples:• It is generally powdered waste products of a suitable color

and density that are used.• Addition of powdered olive stones to drugs like powdered

liquorice and Gentian, powdered Guaiacum wood to Nux vomica.

• Addition of hazel nut shells to cinnamon, exhausted ginger to Ginger, bran.

• Addition of saw dust to powdered Ipeca.• Addition of red sanders wood to chillies.• N.B. if the color of the adulterant needs adjustment, it is

sometimes done by roasting it till the tint is matched.

Evaluation of Crude Drugs

• It includes:• 1- Identification of crude drugs.• 2- Determination of its quality and purity.

• For each official crude drug, there are limits for its quality and purity listed in its monograph (the specified pages of the Pharmacopoeia describing the drug).

• The identity is established by:

Collecting it from a plant that is positively identified.

Comparing it with a preserved sample (herbarium) that is previously identified.

Comparing the unknown drug with a published description of authentic drug sample.

• The quality of crude drugs refer to its active constituents as:

- Carbohydrates- Volatile oils- Glycosides- Alkaloids

• High quality crude drugs is gained through collecting it keeping in mind the following considerations:

1- Correct authenticated natural source.2- Correction at the proper time, stage of

development using proper manner.3- Proper cleaning and drying processes.4- Proper protection of it and of its samples

against insects, fungi, dirt and moisture.

• Targets for crude drugs evaluation:

Investigation of biochemical variation in the drug.

Detection of and deterioration due to treatment and storage.

Determination of purity of the drug i.e. substituted or adulteration.

• Steps of evaluation of crude drugs :

a- Morphological or organoleptic evaluation.

b- Microscopical investigation.

c- Chemical evaluation.

d- Biologic evaluation.

e- Physical evaluation.

a- Morphological or organoleptic evaluation:• The term organoleptic evaluation refers to the

sensory evaluation.

• The characteristics which are evaluated with the help of sense organs such as color, odor, taste, texture…….etc.

• The sensory characters of organized as well as unorganized drugs give the idea about the quality of the drug.

• b- Microscopic evaluation:• Microscopical investigation of unorganized

drugs in an important parameter for the evaluation.

• For the faster and finer transverse sections microtome is used which gives very high degree of thinness with the reproducible results.

• Very fine sections are selectively subjected to staining reactions with various staining reagents for study of chemical nature of the cellular organization.

• Important staining reagents as:

Phloroglucinol and hydrochloric acid for lignified tissues.

Chloro-zinc iodide reagent for cellulosic tissues.

Tincture of alkannol for subrised or cuticularized walls.

Ruthenium red for gums and mucilage containing cells.

• Another important aspect of microscopical evaluation is the study of surface constants.

• The leaf constants like stomatal number, stomatal index, palisade ratio, vein islet and vein termination number are studied by using camera lucida.

• These constants are used for the detection of their adulteration.

• c- Chemical evaluation:It comprises of different chemical tests &

chemical assays.

Preliminary phyto-chemical screening is a part of chemical evaluation for establishing chemical profile of drugs.

Isolation, purification and identification of active constituents are chemical methods of evaluation.

• d- Biological evaluation:• Includes the quantitative assay of the drugs using

biological models of intact animals, animal preparations, isolated living tissues or micro-organisms.

Bioassy: is the assay of pharmacologically active substances by using biological means yields valuable information about the potency of the drug.

- When the intact animal is used for the bioassy, the specific strains of experimental animals may be used.

- i.e. rats, mice, guinea pigs, rabbits, cats, dogs, pigeon….etc., are commonly used experimental animals.

Micro bioassay:- is a type of biological assay specially preformed

with micro-organisms, i.e. bacteria and fungi.- In a typical microbiological assay, evaluation is

performed on the various cultures of micro-organisms and the activity is represented on the basis of average response of a large population of micro-organisms.

- The micro bioassay procedures are used for vitamins like Niacinamide, Calcium pantothenate and Vitamin B12…..etc., for the evaluation of potency of antibiotics.

Chemical examination of plant constituents

Alkaloids

Mayer’s test Dragendorff’s reagent

Hager’s reagent Wagner’s reagent

Carbohydrates

Molisch’s test

Fehling’s test

Benedict’s test

Aniline acetate test

Bial’s testTannic acid test

Cobalt chloride test

Barfoed’s test

Seliwinoff’s test

Iodine test

Tollen’s test

Glycosides

(i) Anthraquinone

Glycosides

(ii) Cardiac

Glycosides

(iii) Cyanogenetic

Glycosides(iv) Flavonoid Glycosides

(v) Saponin

Glycosides

Grignard’s test

(i) Anthraquinone

Glycosides

Micro-sublimation test.

Borntrager’s test.

Modified Borntrager’s test.

(ii) Cardiac Glycosides

(a) Cardenolides

(b) Bufedanolide

(c) Deoxy sugar

in cardiac glycosides

1-Baljet’s test.

2-Legal’s test.

3-Kedde’s test.

Liebermann’s test.

Killer-Killani’s test.

(iv) Saponin Glycosides

Foam test. Haemolytic test.

Liebermann’s test.

(v) Flavonoid Glycosides

(vi) Coumarin Glycosides

a-Shinoda test.

b- Lead acetate test.

Fluorescence test.

Phytosterols Fixed oils and Fats

Liebermann Burchard’s test.

a- Spot test.b- Saponification

test.

Phenolic compounds and tannins

a- Ferric chloride test.b- Gelatin test.

c- Lead acetate solution.

Proteins and amino acids

a- Millon’s test.b- Biuret test.

c- Ninhydrin test.

Gums and Mucilage Volatile oil

Hydro-distillation method for essential oil

a- Alcoholic precipitation.b-Molisch’s test

Plant tissues

Meristimatic Tissues Permanent Tissues

Apical Meri-stem

Lateral Meri-stem

PhotodermPro-cambiumGround meristem

Vascular Cambium

Cork Cambium

Cell wall chemical impregnations

Permanent Tissues

Simple Complex

Ground tissuesEpidermis

Vascular tissues

Xylem Phloem Periderm Parenchyma Collenchyma Periderm

Cell Wall Chemical Impregnations

Cutin

Lignin

Suberin

Hemi-cellulose

Chitin

• These tissues change into other tissues on development, examples:

Meristimatic tissue: is characterized by the following:- Small, thin walled cuboidal closely arranged

cells.- Multiply by the process of cell division.- The cells without intercellular spaces.- Newly formed cells may become differentiated

into mature permanent tissues.

I-Temporary tissues

• Located: - near tips of roots - in buds at tips of stems (apical meristems) - between wood and bark of trees. - model joints of such plants as grasses. - and wherever extensive growth occurs.• Apical Meristem: - involved in primary plant body.i.e.: - protoderm develop to give epidermis. - procambium give xylem and phloem. - ground meristem develop to give cortex,

pitch which give rise to primary plant tissues.

• Lateral Meristem (Secondary Tissue):• Vascular cambium develops into xylem and

phloem• Cork cambium develops into phellogen,

periderm, cork and cork parenchyma.

• usually don’t change into other kind of tissues• In most cases retain their structure and

functional characteristics throughout life.

• Simple tissues:• formed of one kind of cells mainly constructed

similarly and performing one kind of function.

II-Permanent tissues

• 1- Epidermis (epi- : upon, derma: skin):- usually one cell thickness where cells are

usually colourless.- Guard cells which control gas movement

through epidermal pores called (Gr. Stoma opening).

- Possess chlorophyll in bodies called chloroplasts.

- Outer cell walls often coated by a waterproof, waxy cutin (cuticle).

• Exceptions:

• a- Epidermal cells of roots have extensions called root hairs.

• b- Some epidermal cells are modified i.e. exhibit secretory function.

• c- Some epidermal cells of the plant parts have epidermal hairs above ground form outgrowths of one or several cells.

• 2- Ground tissue:• a- Parenchyma; (Greek, para-: besides, en- in,

chin: pour):• consists of thin walled cells that are

approximately isodiametric • e.g. not much longer than they are wide.• The individual cells may be spherical, cubical,

many sided or irregular in shape, they contain living protoplasm and retain their property of cell division even tough division may never occur after the cells are mature.

• The presence of living protoplasm also means they can function in the storage of water and food, or in photosynthesis and even secretion, in wound healing

• They are found abundantly in higher plants in roots, stems, leaves, fruits and flowers.

• Green chlorophyll bearing parenchyma cells of leaves and green stems are called chlorenchyma.