J. Trop, Mea. Plants. Vol. 10. No. 1 (June 2009)

Hypoglycémie Activity of Certain Plant Extracts Used on Rats

Chee Beng Jin

Medicinal Plant Division. Forest Research Institute Malaysia (FRJM),52109 Kepong. Selangor. Malaysia.

Email: cheebengjin@yahoo.com

Abstract: Traditional herbal remedies for treattnent of diabetes are cotnmon in tnany cultures and societies. A Malaytraditional herbal preparation is claimed to lower the blood glucose content in diabetes patients. The preparation consistsofthe extracts of Tinospora crispa. Momordica charantia. Alpinia galanga and Portulaca olerácea. The same preparationwas used to verify the claimed hypoglycémie property using rats. Five doses (2.5, 25, 250, 500 and 2500 mg/kg bodyweight) of the aqueous extracts were administered. The dose of 500mg/kg body weight lowered the blood sugar levelsignificantly . The hypoglycémie mechanism ofthe mixed herbal preparation is yet to be identified.

Keywords: Hypoglycémie activity, Alpinia galanga. Momordica charantia, Portulaca olerácea, Tinospora crispa

INTRODUCTION

Plants remaiti the main source of medication forpatients with diabetes from the ancient to modernhuman civilizations. In many parts ofthe world,they are sometimes taken in preference to othertreatments. Globally, there are more than 1000plants reputed to be hypoglycémie (Day andBailey, 2006) and abotjt 292 plant species areused for the treatment of diabetes in Malaysia(Liza and Hamdan, 2004) and most of whichare poorly studied. Among the plants reputedlyused are Alpinia galanga, Momordica charantia,Portulaca olerácea, Tinospora crispa (Maries andFarnsworth, 1995)

2) or locally called Patawali is widespread in theMalesian region. It occurs from India Sri Lanka,south China, Peninsula Malaysia to the Philippines.In Malaysia and Indonesia, the stem and leaves ofT. crispa are traditionally used for treating diabetes(Fasihuddin and Hasmah, 1993, Umi Kalsom, et al.,1999, Shamsul, et. al., 2003 and Samy, et al., 2005),also commonly used in other Asian countries totreat diabetes (Monique and Melanie-Jayne, 2006).

Portulaca olerácea (Family: Portulacaceae) (Figure3) is locally known as Beremi or Gelang Pasir, It isa widespread weed that probably originated fromtropical America, The young shoots and stem areeaten raw or cooked as vegetable, especially inIndian cooking. The World Health Organisationhas named P. olerácea in its most used medicinalplants (Ong, 2004), also reported to decrease bloodglucose levels (Samy, et al., 2005), The plant wasreported to be used for treatment of diabetes inIndia, Africa and Europe (Monique and Melanie-

Jayne, 2006).

Momordica charantia (Family: Curcubitaceae)(Figure 4) or Peria Katak in Malay, originated fromeastern India and southern China, found widelythroughout the tropics and cultivated in SoutheastAsia, The fruits of M. charantia are a popularlocal vegetable either eaten raw or cooked. In localtraditional medicine, consuming the fruit in rawform or blended as juices is used to treat diabetes(Shamsul, et. al., 2003, Samy, et al., 2005 and Wiart,2006). Elsewhere in Africa, India, Central America,Australia and the Middle East, the fruit and leaveswere reported to be used for diabetes (Monique andMelanie-Jayne, 2006). (Nguyen and Sri Hayati,1999).

Alpinia galanga (Family: Zingiberaceae) (Figure 5)locally called Lengkuas in Malay, originated fromIndia and is now widely cultivated in tropical Asia.It is mainly used as spice, in traditional medicine aswell as an ornametital (Halijah, 2001), It is easilypropagated using the rhizome. The fresh rhizomesand flowers are consumed raw. In Malaysia andIndia, the infusion ofthe Lengkuas rhizomes is usedfor treating diabetes (Samy, et al., 2005, Moniqueand Melanie-Jayne, 2006).

A local Malay traditional medicinal practitionerin the state of Johor in Malaysia claimed that thecombination of all the four plants was effectivein lowering the blood glucose level in diabeticpatients. (Broadhurst, 1997 and Li, 2000), Studieswere carried out to explore and validate the aboveclaimed hypoglycémie effects and results obtainedare reported.

J. Trop. Mea. Plants. Vol. îONo. 1 (June 2009)

MATERIALS AND METHOD

Experimental Animals: Normal adult white rats ofthe Spraque-Dawley strain were obtained from the AnimalHouse of Biology Department, Universiti Putra Malaysia. Male rats with body weights ranging between 200-350gwere selected and kept in a cage measuring 50cm x 32cm x 19cm. Tbey were fed witb ample kernel rat pellet andwater. Male rats were used in order to avoid tbe interaction of tbe oral hypoglycémie agent with hormonal changesand possible pregnancy in female rats (Carter, 2005).

Experimental design: Seven experimental groups, each with 5 rats were formed. The first group was given salinesolution (0.98%) and the second group given glibenclamide (lOmg/kg body weight). The other 5 groups were givenaqueous extract of doses 2.5,25, 250, 500 and 2500 mg/kg rat body weight respectively. The aqueous extracts weregiven once at the beginning ofthe experiment at time -30 minutes.

Aqueous extract preparation: Fresh plants of Alpiniagalanga (0.70kg), Momordica charantia (L40kg), Portulacaolerácea (0.70kg) and Tinospora crispa (0.16kg) were washed, cut and boiled in 9 liters of distilled water under slowflame for 4 hours. Tbe liquid obtained was sieved, cooled and finally centrifuged to separate tbe plant debris fromthe supernatant. The supernatant was dehydrated in a rotary evaporator and finally freeze-dried to obtain dark browncrystals.

Oral Glucose Tolerance Test (OGTT): The normal rats were fasted for 18 hours prior to tbe test. Initial bloodsampling was recorded at time -30 minutes and followed by the oral administration of treatments or control. After30 minutes, blood samples were taken and eacb group was given a glucose load (1.5g/kg body weight). Subsequentblood samplings were taken at 5,15,30, 60, 90, 120,150,180 and 210 minutes.

Blood glucose assay: Blood glucose concentrations at time -30, 0, 5, 15, 30, 60, 90, 120, 150, 180 and 210 minutesfor each group were determined by using Glucose Oxidase Kit. Absorbanee readings were obtained at 510nm. Theplasma glucose concentration was calculated by using the formula: blood glucose concentration (mg%) = (Absorbaneeof Sample)/(Absorbanee of Standard) X 100.

Area under curve: Area under the curves (AUCs) were calculated by the trapezoidal integration method (Campbelland Madden, 1990)

Statistical analysis: Statistical analysis was performed using ANOVA and Student's t-test. Differences wereconsidered to be significant when P<0.05. The results are expressed as mean values ± S.E. (Standard Error).

RESULTS AND DISCUSSIONS

The average blood glucose levels for the normal rats in the complete Oral Glucose Tolerance Test are representedin Figure 1. The blood glueose values at tbe beginning ofthe experiment (-30 minutes) showed no difference in allrats. They were a!l in the narrow normal blood glucose range (70-110mg%) after an 18-hour fast (Beers, 2003). Aftertbe treatment at -30 minutes, the blood glucose readings for 500 and 2500 mg/kg body weight was higher than thetwo controls; saline and glibenclamide at minute 0. The plant extracts had 14% glucose. Therefore, the high naturalglucose content had contributed the higher glucose values. The presence of natural glucose was possibly due to tbecarbohydrate content found in A. galanga. M. charantia and P. olerácea (Ismail, 2000 and Ong, 2004).

After glueose load, the blood glucose levels in the rats rose comparatively higher and increased until they reacheda peak value (Table 1). Normal rats fed with 2500mg/kg body weight (0.69 ± 0.21 mg%/min) and 500mg/kg bodyweight (1.03 ± 0.25mg%/min) of extract showed lower average rate of increase compared to glibenclamide (1.11± 0.30mg%/min). The higher doses prevented the sudden increase of glucose level in tbe rat blood plasma. Thefindings suggested tbat the likely existence of unknown substances or secondary metabolites in the two higher dosesenabled to hold back tbe glucose surge.

J. Trop. Med. Plants. Vol. lONo. 1 (June 2009)

a 50

1 r 1 • 1 1 1 1 1 1 1

-30 0 5 15 Î0 60 90 120 150 180 210

Time (Minuteil

• Saline ••- Glibenclamide — 9 — 2.5mg/kg —•— 25mg/kg

• 250mg/l(6 - -•• - 500nig/ltß —•— 2500mgAg

Figure 1: Average Blood Glucose Levels in Normai Rats in the Oral Glucose Tolerance Test

Table I: Rate of Blood Glucose Level Increase From 0 Minute To Peak and the rate of Blood Glucose LevelDecrease From Peak To 210 Minutes

Treatment

Saline

Glibenclamide

2.5 mg of Extract

25 nig of Fxtract

250 mg of Extract

500 mg of Extract

2500 mg of Extract

Rate of Increase(mg%/min±SE)

1.72 + 0.49

1.11 +0.30

1.59 + 0.42

2.74 + 0.41

1.88 + 0.43

1.03 + 0.25*

0.69 + 0.21*

Rate of Decrease(mg%/min ± SE)

0.54 + 0.12

0.41 + 0.22

0.90 + 0.38*

0.87 + 0.45

0.64 + 0.11

0.95 + 0.33*

0.36 + 0.12

Time of Glucose peakvalues (minutes)

60

60

90

60

60

90

90

Note: Results are presented as Mean ± S.E.M.* Shows mean values significantly different compared to saline control (P<0.05)

Glibenclamide-treated rats had the lowest peak ofthe glucose load (150.88 ± 9.99 mg%) (Figure 1). These resultswarranted that the established Oral Hypoglycaemic Agent (glibeticlamide) was able to stimulate insuliti dischargefrotn the ß-cells in normal animals (Henry, 2007). The dose highest dose of 2500 mg/kg body weight had a lowerpeak (185.76±16.33mg%) than saline (l92.00±5.56mg%). The other peak values of doses of 500mg/kg bodyweight (201.44±11.37tng%) and 250mg/kg body weight (214.69±17.46mg%) also did not differ statistically fromsaline. Moreover, the effect of all the extracts was less pronounced compared to glibenclamide.

There was a decrease in all the glucose readings after the peak values for all treated rats until the end ofthe test.Interestingly, from minute 120 to 210, the average blood glucose level for 500mg/kg body weight dose was lowerthan saline (Figure 1). The dose of 500mg/kg body weight was the only extract that reduced the blood glucoselevel to a basal value at minute 210 which was similar to glibenclamide (Figure 1). The blood glucose levels for theother extracts did not reach basal values. Moreover, the rate of blood glucose level decrease was also the highest inthe 500mg/kg body weight (0.95 + 0.33 mg%/min) compared to saline (0.54 + 0.12 mg%/min) and giibenclamide(0.41 + 0.22 mg%/min) (Table 1).

Areas under the blood glucose concentration curves (AUC) were calculated from minute 0 to 210 are the same

J. Trop. Med. Plants, Vol. ¡0 No. ! (June 2009)

data used to determine the amount of blood glucose level (Hallfrisch and Behall, 2000). The total area under thetolerance curve represents the total concentration ofblood plasma glucose for a certain time interval (Rydberg, et al..1994). As anticipated, the glibenclamide-treated rats had the most minimal AUC value (25008.87 ± 661.57mg%min)compared to saline. Interestingly, when the AUC values of saline and dose 500mg/kg body weight were compared,both values were not significantly different and results were comparable.

Prabhakar and Doble (2008) reported that there were around 410 experimentally proven medicinal plants havingantidiabetic properties but the complete mechanism of action is available only for about 109 plants. The reportedhypoglycémie property of Alpinia galanga, Momordica charantia, Portulaca olerácea, Tinospora crispa weresummarized in Table 2

Table 2: The reported hypoglycémie property of Alpinia galanga, Momordica charantia,olerácea, Tinospora crispa

Portulaca

Plant species

Alpinia galanga

Momordica charantia

Portulaca olerácea

Tinospora crispa

Reported hypoglycémie property

The aqueous and methanol extracts showedhypoglycémie effect as good as to gliclazide, anestablished hypoglycémie agent. The organic andinorganic contents in the rhizome particularly thepolysaccharides might be responsible for the effect.Polysaccharides are known to increase the seruminsulin levels, reduce the blood glucose levels andimprove glucose tolerance

The hypoglycémie property was due to the presenceof vicine, polypepide-p and charantin that boostedglucose uptake and glycogen synthesis in the musclesand liver and suppressed the synthesis of glucose.Charantin, a steroidal saponin is known to have aninsulin-like activity.

The aqueous extract elevates insulin sensitivity indiabetic rats. The mechanism might be related to itsactions in improving lipid metabolism and decreasingfree fatty acids. The oral administration of P. oleráceaextract for three weeks significantly reversedantioxidant enzymes to near normal values in diabeticrats. It might be due to the presence of flavanoids inthe plant

The plasma glucose levels of moderately diabetic ratswere significantly improved after 2 weeks treatment ofaqueous extracts The in-vitro insulinotropic activitywas detected in the human and H1T-T15 beta-cells.The antihypergiycaemic effect of Z crispa is probablydue to stimulation of insulin release via modulationof intracellular Ca-' concentration in pancreatic beta-cells. In another study, the presence of three compoundsin T. crispa with free radical and free scavengingproperty had effective antioxidant property in diabeticcondition

References

Akhtar,etal.,2002,Quanhong, et al., 2005,Mukherjee, et al., 2006.Henry, 2007.

Ng, etai-, 1986McWhorter, 2001.

Shen and Lu, 2003Sharma, et al., 2009Prabhakar, 2008.

Noor and Ashcroft, 1989,Noor, etal., 1989,Noor and Ashcroft, 1998a,Noor and Ashcroft, 1998b,Cavin, etal , 1998,Muhajir et al., 2008.

It is important to consider potential harm from the use of traditional herbal medicine due to the synergistic effect

4

J. Trop. Med. Plants. Vol ¡O No. I (June 2009)

of the chemical components (Ogbonnia, 2008). The use of T. crispa was associated with markedly elevated liverenzymes in 2 diabetes patients (Sangsuwan, et al., 2004). Another study showed that M diarantia were abortiftcantsand not to be used for the period of pregnancy and there were also cases of reported severe hypoglycemia with theuse of M charantia in children {Krawinkel and Keding, 2006). Therefore, extra safety measures should be taken onthe aspects of toxicity, allergic reactions, contaminations and interaction in the usage of non-conventional therapies(McGuffin et al., 1997 and Day, 2005). Plant remedies are unavoidably the foundation of treatments in undevelopedand developing regions in the world. (Martin, 1997). Indisputably, oral hypoglycémie agents will continue to beindispensible especially in diabetes management (Weiss, 1998) but traditional treatments may offer priceless cluesfor the development of new oral hypoglycémie agents or simple nutritional addition (Bailey and Day, 1989).

In conclusion, the traditional herbal mixture of extracts derived from the combination of T. crispa, M. charantia, A.galanga and P. olerácea showed hypoglycémie activity. The synergistic interaction ofthe chemical components inthe mixed extracts impart hypoglycémie property.

ACKNOWLEDGEMENTS

The author thanks the staff of Animal Physiology Lab and Animal House ofthe Biology Department, Faculty ofScience, Universiti Putra Malaysia for their kind assistance.

REFERENCES

Akhtar, M.S., Khan. M.A. and Malik, M.T. 2002. Hypoglycémie activity of Alpiniagalanga rhizome and its extracts in rabbits.Fitoterapia. 73:623-628.

Bailey, C.J. and Day, C. 1989. Traditional plant medicines as treatments for diabetes. Diabetes Care. 12(8):553-64.

Beers, M.H. 2003. The Merck Manual of Medical Information. Second Home Edition. Pocket Books, Simon and Schuster, Inc.,New York.

Broadhurst, C.L. 1997. Nutrition and Non-Insulin Dependent Diabetes Mellitus from an Anthropological Perspective. AltemativeMedicine Review. 2(5):378-399.

Campbell, C.L. & Madden, L.V. 1990. Introduction to plant disease epidemiology. John Wiley and Sons, New York. pp. 192-193.

Carter, W. 2005. The Complete Home Guide to Medication. Hinkler Books Pte. Ltd. Victoria, Australia.

Cavin, A., Hostettmann, K., Dyatmyko, W. and Potterat, O. 1998. Antioxidant and Lipophilic Constituents of Tinospora crispa.Planta Medica. 64(5):393-396.

Day, C. 2005. Are herbal remedies of use in diabetes? Diabetes Medicine. 22:10-12. Day, C and Bailey, C.J. 2006. Preclinicaland Clinical methods for evaluating antidiabetic activity of plants. (In: Traditional Medicines for Modem Times: AntidiabeticPlants Edited by Soumyanath. A.) CRC Press, Taylor & Francis Group. Boca Raton. USA.

Fasihuddin. A. and Hasmah, R. 1993. Kimia Hasilan Semula Jadi dan Tumbuhan Ubatan (Natural Product Chemistry andMedicinal Plants). Dewan Bahasa dan Pustaka, Kuala Lumpur.

Halijah, 1. 200\.Alpinia Roxb. In: van Valkenburg, J.L.C.H and Bunyapraphatsara, N. (Editors): Plant Resources of South-EastAsia No 12(2). Medicinal and Poisonous Plants. Backhuys Publishers, Leiden, the Netherlands, pp. 52-61.

Hallfrisch, J. and Behall, K.M. 2000. Improvement in insulin and glucose responses related to grains. Cereal Foods World.45(2):66-69. ¡

Henry, J.A. 2007. New Guide to Medicines and Drugs. 7th Edition. Dorling Kindersley Ltd. London.

Ismail, S. 2000. Sayuran Tradisional, Ulam dan Penyedap Rasa (Traditional vegetables, salads and appetizers). Pusat PengurusanPenyelidikan, Universiti Kebangsaan Malaysia.

Krawinkel, M.B. and Keding, G.B. 2006. Bitter gourd {Momordica charantia): a dietary approach to hyperglycemia. NutritionReview. 64:331-337.

Li, S.C. 2000. Medicinal plants: Culture, Utilization and Phytopharmacology. Technomic Publishing Company Ltd. Lancaster,U.S.A.

J. Trop. Med. Plants. Vol. 10 No. ¡ (June 2009)

Liza, O and Hamdan, N. 2004. Malaysian anti-diabetic plants. Proceedings ofthe Seminar on Medicinal Plants. (Eds: Chang,Y.S., Mastura, M. and Nurhanan, M.Y.). 20-21 August 2002, Forest Research Institute Malaysia.

Maries, R.J. and Famswotih, N.R., 1995. Antidiabetic plants and their active constituents. Phytomedicine. 2(2):I37-I89.

Marlin, G.J. 1997. Ethnobotany: a methods manual. Chapman and Hall. London.

McGuffin, M., Hobbs, C , Upton, R. and Golberg, A. 1997. American Herbal Products Association's Botanical Safety Handbook.CRC Press, Boca Raton. U.S.A.

McWhorter, L.S. 2001. Biological complementary therapies: a focus on botanical products in diabetes. Diabetes Spectrum.14:199-208.

Monique, S.J.S. and Melanie-Jayne, R.H. 2006. Plants used in the treatment of Diabetes. (In: Traditional Medicines for ModemTimes: Antidiabetic Plants Edited by Soumyanath, A.) CRC Press, Taylor & Francis Group. Boca Raton. U.S.A.

Muhajir, H., Siti Pauliena, M.B., Mohd. Saufi, B., Abdul Manaf, A., Nik Musa'adah. M and Khozirah, S. 2008. Evaluation ofinsulinotropic activity of Malaysian traditional plant extracts. Joumal of Biological Sciences. 8(l):20I-204.

Mukherjee. P.K., Maiti, K.. Mukherjee, K. and Houghton, P.J. 2006. Leads from Indian medicinal plants with hypoglycémiepotentials. Journal of Ethnopharmacology 106:1-28.

Ng, T.B., Wong. CM., Li, W.W. and Yeung, H.W. 1986. Insulin-Iike molecules in Momordica charantia seeds. Joumal ofEthnopharmacology. 15:107-117.

Nguyen, H.H. and Sri Hayati, W. 1999. Momordica L. In: de Padua, L.S., Bunyapraphatsara, N. and Lemmens, R.H.M.J.(Editors): Plant Resources of South-East Asia No 12(1). Medicinal and Poisonous Plants. Backhuys Publishers, Leiden, theNetherlands, pp. 353-359.

Noor, H., Hatiimonds. P., Sutton, R. and Ashcroft, S.J.H. 1989. The hypoglycaemic and insulinotropic activity of Tinosporacrispa: studies with human and rat islets and H1T-T15 B-cells. Diabetologia. 32:354-359.

Noor, H. and S.J.H. Ashcroft. 1989. Antidiabetic effects oí Tinospora crispa in rats. Joumal of Ethnopharmacology. 27:149-161.

Noor, H. and S.J.H. Ashcroft. 1998a. Insulinotropic activity oí Tinospora crispa: Effect on ß-cell Ca * handling. PhytotherapyResearch. 12:98-102.

Noor, H. and S.J.H. Ashcroft. 1998b. Phamiacological characterization ofthe antihypergiycaemic properties on Tinospora crispaextract. Joumal of Ethnopharmacology. 62:7-13.

Ogbonnia, S.O., Odimegwu, J.I. and Enwuru, V.N. 2008. Evaluation of hypoglycaemic and hypolipidaemic effects of aqueousethanolic extracts of Treculia qfricana Decne and Bryophyllum pinnatum Lam. and their mixture on streptozotocin (STZ)-induced diabetic rats. African Joumal of Biotechnology. 7(15):2535-2539.

Ong, H.C. 2004. Sayuran: Khasiat Makanan dan Ubatan. (Vegetables: Nutritional and Medicinal Values). Utusan Publicationsand Distributors Sdn. Bhd., Kuala Lumpur.

Prabhakar. P.K. and Doble, M. 2008. A Target Based Therapeutic Approach Towards Diabetes Mellitus Using Medicinal Plants.Current Diabetes Reviews, 4(4):29l-308.

Quanhong, L., Caili, F., Yukui, R., Guanghui, H. and Tongyi, C. 2005. Effects of protein-bound polysaccharides isolated frompumpkin on insulin in diabetic rats. Plant Foods for Human Nutrition. 60:13-16.

Rydberg, T., A. Jonsson, M. Roder and A. Melander. 1994. Hypoglycémie activity of glyburide (glibenclamide) metabolites inhumans. Diabetes Care. 17(9): 1026-1030.

Samy, J., Sugumaran, M. and Lee, K.L.W. 2005. Herbs of Malaysia. Federal Publications Sdn. Bhd. Kuala Lumpur.

Sangsuwan, C , Udompanthurak. S, Vannasaeng, S. and Thamlikitkul, V. 2004. Randomized controlled trial of Tinospora crispafor additional therapy in patients with type 2 diabetes mellitus. Joumal of Medical Association Thailand. 87:543-546.

Shamsul, K., Tajuddin, A.M. and Mazina, M.Y. 2003. Tumbuhan Ubatan Tradisionai Malaysia (Malaysian Traditional MedicinalPlants). 1st Edition. Institut Biosains, Universiti Putra Malaysia.

Sharma, A., Vijayakumar, M.; Rao, C. V.; Unnikrishnan, M.K.; and Reddy, G.D. 2009. Action of Portulaca olerácea againstStreptozotocin-Induced Oxidative Stress in Experimental Diabetic Rats. Joumal of Complementary and Integrative Medicine.

J. Trop. Med. Plants. Vol. ¡ONo. ! (June 2009)

6(0:1-12,

Shen. L. and Lu, F. 2003. Effects of Portulaca olerácea on insulin resistance in rats with type 2 diabetes mellitus. ChineseJoumal of Integrative Medicine. 9:289-292.

Umi Kalsom, Y., Horsten, S.F.A.J. and Lemmens, R.H.M.J. 1999. Tinospora Miers. In: de Padua, L.S., Bunyapraphatsara, N.and Lemmens, R.H.M.J. (Editors): Plant Resources of South-East Asia No 12(1). Medicinal and Poisonous Plants. BackhuysPublishers, Leiden, the Netherlands, pp. 479-484.

Weiss. R. F. 1998. Herbal Medicine. 6th Edition, Beaconsfield Publishers Ltd, London.

Wiart, C. 2006. Medicinal Plants ofthe Asia-Pacific: Drugs for the future? World Scientific Publishing Co. Pte. Ltd. Singapore.

Figure 2: Tinospora crispa plant with heart-shaped leaves (left) and dried stems (right).

Figure 3: Portulaca olerácea plant and flowers (left) and succukiii sieiii and leaves (riglil).

J. Trop. Med. Plants. Vol. 10 No. I (June 2009)

Figure 4: Momordica charantia plant (left) and flowers and fruits (right).

Figure 5: Alpinia gaianga leaves, flowers and rhizome.

Copyright of Journal of Tropical Medicinal Plants is the property of Tropical Botanics Sdn Bhd and its content

may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express

written permission. However, users may print, download, or email articles for individual use.