368 Planta Med. 56(1990)

Antimalarial Activity of Tanzanian Medicinal Plants1 H. Weenen2, M H. H. Nkunya23, D. H. Bray4. L. B. Mwasumbi5, L. S. Kinabo2. and V. A. E. B. Kilimali6 2

Part 1 in this series Department of Chemistry, University of Dares Salaam, P.O. Box 35061, Dares Salaam, Tanzania Address for correspondence Department of Medical Protozoology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1 E 7HT, U.K.

6

Department of Botany. University of Dares Salaam, P.O. Box 35060, Dares Salaam, Tanzania National Institute for Medical Research, Amani Research Centre, P.O. Box 4, Amani, Tanzania

Received: June 22, 1989

Tanzanian medicinal plants were extracted and tested for in vitro antimalarial activity, using

the multidrug resistant K1 strain of Plasmodium falciparum. Of 49 plants investigated, extracts of three plants were found to have an IC50 between 5—10 .tg/ml, extracts of 18 other plants showed an IC50 between 10 and 50 .tg/ml, all others were less active. The three most active extracts were obtained from the tubers of Cyperus rotundus L. (Cyperaceae), the rootbark of Hoslundia op-

posita Vahl. (Labiatae), and the rootbark of Lantana camara L. (Verbenaceae).

Key words Tanzanian, medicinal plants, antimalarial activity, Plasmodium falciparum, Gyp erus rotundus, Hoslundia opposita, Lantana camara.

Materials and Methods Plant materials All plants were collected from Dar es Salaam, Tanga, and Mwanza regions, except for Artemisia afro Willd,

which was collected from the Mbeya region. Voucher specimens were deposited at the herbarium, Botany Department, University of Dares Salaam.

Extraction and isolation procedures The plant materials were dried, pulverized and extracted either consecutively with petroleum ether (h.p. 40— 60°C), dichioromethane and methanol, 2 x 48 h for each solvent. or with methanol alone. The concentrated extracts were tested for in vitro antimalarial activity.

Anti-malarial testing Plant extracts were assessed for in vitro activity

against Plasmodium falciparum strain K1, which originated in Thailand, and which is multidrug resistant (2). The technique used measured the ability of the extracts to inhibit the incorporation of [3H]-hypoxanthine into the malaria parasites. Precise details of the

protocol are described in references (3) and (4). Extracts were

Introduction Plants continue to be used in the treatment of malaria, either for their anti-parasitic activity, or because

they possess, or are believed to possess, other activities with therapeutic value for a patient with malaria. Tanzania is estimated to have 60 thousand traditional healers, and most of them also prescribe one or more plants for the treatment of malaria. Because of an obvious need for new noncross-resistant and less toxic antimalarial drugs, we have screened extracts of 49 plants for antimalarial activity.

Plants that were collected are plants which are used traditionally for the treatment of malaria, as well as plants from families which have been reported to contain a plant or plants with potent antimalarial activity. These include the families Simaroubaceae, and Amaryllidaceae (1). The extracts were tested for in vitro antimalarial activity, using the multidrug resistant K1 strain ofPlasmodiumfalciparum (2).

tested in duplicate at 12 concentrations in threefold dilutions starting from 500 ig/ml.

Results and Discussion Among the extracts of all 49 plants investigated, three were in the category of the highest antimalarial activity, i.e. their IC50 was between 5 and 10 .tg/ml (Table 1). These included the dichioromethane extract of the tubers of Cyperus rotundus, and the hexane extracts of the roots of

Hoslundia opposita and Lantana camara. Extracts of 18 other plants showed activity with an IC50 between 10 and 50 .tg/ml, all others had less or no activity.

For comparison, the methanol extract of a Cinchona species, grown in Usambara, Tanzania, was also tested. Its IC50 was found to be 0.5 tg/ml. We would like to emphasize that care must be taken when interpreting the results of the anti-malaria testing of the extracts. Seasonal and regional variations have not been considered, but can be significant. Also the data obtained in this study cannot be correlated directly with the effects of a traditional treatment, since methods of preparation, effects of combinations of plant extracts, and

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Abstract

Planta Med. 56(1990) 369

AntimalarialActivity of Tanzanian Medicinal Plants family

species

part used

Ref.

IC50

Table 1 Antimalarial activity of extracts of Tanzanian plants

P. E CH2CI2 MeOH

Anacardiaceae

Crinumstuhlmannii Cr/numportifolium Crinumpapiosum Scadoxus multiflorus Ozoroainsignis Sclerocarya cafra

Apocynaceae

Sorindeia madagascariensis Rauwoif/a mombasiana

wh. plant wh. plant wh. plant

wh. plant root bark stem bark

N. D. N. D. N. D. N. D. —

N.D.

Caesalpiniaceae

Caesalpinia bonduc

stem bark leaves wh. plant

Cassiaabbrev/ata

root bark

Cassia occidental/s

wh. plant

Tamarindusindica

fruits

Catha edulis Artemisia afra

aerial root bark aerial

Conyzapyrrhopappa Crassocephalum bojeri Tr/daxprocumbens

leaves

Vernoniaamygda//na

leaves root bark stem bark leaves tubers

N.D.

aerial

N. 0.

Compositae

Vernon/a colorata

Cyperaceae Euphorbiaceae

Cyperusrotundus

root bark

C/ut/a robusta

Guttiferae

Vismiaorientale

Labiatae

Hoslundia opposita

leaves root bark

stembark Ocoteausambarens/s Acacia clav/gera Albiz/a anthelmint/ca P/liost/gma thonn/ng/i

Meliaceae

Azadirachta md/ca

Myrtaceae Olacaceae Plantaginaceae Rosaceae Rubiaceae

Entandrophragma bussei P/s/diumguajava X/meniacafra Plantago major Par/nar/exelsasab/n Crossopterixfebrifuga Gardenia jov/stonantis

Vangueria /nfausta

leaves leaves wh.

plant stem bark stem bark stem bark leaves

fruit root bark stembark

Rutaceae

Clausenaan/sata

root bark

stem bark leaves Todal/a as/at/ca

root bark

Zanthoxylumg/llet//

stem bark root bark

Zanthoxylumxylubeum Tiliaceae

Verbenaceae Zygophylaceae

Grew/a eggling/i Grewia forbes/i Lantana camara Balan/tes aegypt/ca

—

—

7 5 7 6 —

—

5

—

—

—

—

N. 0.

—

*

*

—

—

—

ND.

N.D.

—

N. D.

N. 0.

—

6 5

5,6,7 6 9 6 —

*

6 6 6

*

—

N.D.

—

6 —

—

—

—

—

—

—

***

*

— ND. ND. **

root bark

stem bark stem bark stem bark leaves stem bark leaves stem bark

1

N. 0.

wh.plant

root bark root bark stembark

Lauraceae Leguminosa

—

aerial

Bride/ia cathartica

Margar/taria d/scoidea

ND.

root bark

1 1

—

Bignoniaceae

Celastraceae

—

bark root bark root

stem bark

1 —

—

Gussoniaarborea K/gel/a africana

Araliaceae

N. D. N. D. N. D. N. D.

—

—

N. D. —

6

—

—c

•

7

ND.

—

—

N.D.

—

—

—

—

*

—

—

—

6 6

7 6

5

* N. D.

5

—

N. 0. **

5 — —

_d —

*** —

* *

••

..*

N. D.

N. D.

N.D.

ND.

_d

7 —

5

—

_d

5

— — ND. —

— —

—

—

6 5

ND.

— —

—

*

6 —

**

*

—

—

5 5 — —

stem bark stem bark stem bark

*

N. D.

leaves

—

root bark stem bark

—

*

6 N. D.

—

*

7 10 —c

• IC50 values have been categorized as follows: "": IC50 = 5—9 .sglml; ": IC50 = 10—49 .sg/mI; *: IC50 = 50—99 ug/ml; : IC50 = 100—499 ig/mI; —: 1C50>499 g/ml; N. D.: not determined. Refers to source of information on its medicinal use. Lugakingira, E., personal communication. Used locally.

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Amaryllidaceae

370 Planta Med. 56(2990)

Acknowledgements

References 1 2

'

Part of this research was supported by a grant

Advances in malaria chemotherapy (1984) WHO, Geneva, Technical

Report Series 711, 142. Thaithong, S., Beale, G. H., Chutmongkonkul, M. (1983) Trans. Roy. Soc. Trop. Med. Hyg. 77, 228. Desjardins. R. E., Canfield, C. J., Haynes, J. D., Chulay, J. 0. (1979) Antimicrob. Agents Chemother. 16, 710. O'Neill, M. J., Bray, D. H., Boardman, P., Phillipson, J. D., Warhurst, D. C. (1985) Planta Med. 394. Watt, J. M., Breyer-Brandwijk, M. G. (1962) Medicinal and poison-

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from the University of Dares Salaam.

Livingstone Ltd., Edinburgh, London, 1962.

6 Kokwaro, 0. (1976) Medicinal plants of East Africa, East African LitS

erature Bureau, Kampala, Nairobi, Dar es Salaam. Haerdi, F. (1964) Acta Tropica, Suppl. 8,1. Hedherg, I., Hedherg, 0., Madati, P. 5., Mshigeni, K. E., Mshiu, E. N., Samuelsson, G. (1982) J. Ethnopharmacology 6, 29; (1983) 9, 105, 237.

Kerharo, J., Adam, J. G. (1974) La Pharmacopde Sénégalaise Vigot Frères, Paris. ° Traditionelle, Pernet, R. (1957) Mémoires de l'Institut Scientifique de Madagascar, Série B, VIII.

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storage conditions were not taken into consideration. Finally, traditional healers may prescribe plants for their anti-pyretic effects, rather than for direct anti-malarial effects. Some of the plants may contain antipyretic principles rather than antimalarial substances, and their therapeutic value was therefore not recognized.

H. Weenen et aL