In vitro antiplasmodial activity of some plants used in Kisii, Kenya against malaria and their chloroquine potentiation effects
Introduction
Plasmodium falciparum, the most widespread etiological agent for human malaria is becoming increasingly resistant to standard antimalarial drugs which necessitates a continuous effort to search for new antimalarial drugs. Plants have invariably been a rich source for new drugs and some antimalarial drugs in use today (quinine and artemisinine) were either obtained from plants or developed using their chemical structures as templates (Gessler et al., 1994). Scientific evaluation of medicinal plants used in the preparation of traditional medicine has in the past provided modern medicine with effective drugs for the treatment of parasitic diseases (Iwu et al., 1994).
Over the past years, the scientific progress in malaria chemotherapy has been more on the effects of already existing drugs than the development of new ones. The search for new antimalarial drugs has regained importance due to resurgence of drug resistant parasites in many countries. Malaria chemotherapy and prophylaxis are now targeting drug combinations with the hope of achieving drug potentiation to circumvent or delay resistance (Zucker and Campbell, 1993, WHO, 2000). In South East Asia, the use of firstline drugs with artemisinine derivates such as artesunate have shown to increase efficacy, protect drugs against resistance development, reduce transmission of malaria and increase the lifespan of antimalarial compounds (TDR, 2000). In Kenya, chloroquine (CQ) has been discontinued as the firstline treatment for malaria due to overwhelming presence of resistant P. falciparum strains. Reports of resistance to sulfadoxine-pyrimethamine, which is currently used as the firstline drug, are on the increase (WHO, 1998, WHO, 2000, USN, 2001).
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Plant materials
The plant samples were collected between March and September 1999 from Kisii District, Nyanza Province, Kenya based on ethnomedical use through interviews with local communities (Table 1). These were identified and voucher specimens deposited at the Herbarium, Botany Department, University of Nairobi, Nairobi. The plant parts were air-dried under shade and ground using a laboratory mill (root bark and stem bark) and a kitchen blender (leaves).
Extraction
For each plant part, 25 g of the chaff was boiled
Results and discussion
In the preliminary studies, all the 55 extracts from the 11 plants were screened against K39. At least one extract from 73% of all the plants screened against K39, a CQ-sensitive P. falciparum isolate, showed activity of IC50 values below 100 μg/ml (Table 2). The extracts that were with IC50<20 μg/ml were further assayed against NF 54, ENT 30 and V1/S (Table 3).
For K39, the two plants from Rhamnaceae (R. prinoides and R. staddo) showed mild antiplasmodial activity with methanol extracts being
Conclusion
The fact that 73% of the plants screened in vitro had some level of antiplasmodial activity would justify their ethnopharmacological uses as traditional antimalarials. After detailed in vivo antimalarial evaluation and thorough toxicological studies, some of these plants may be recommended as antimalarials in known dosages especially in rural communities where the conventional drugs are unaffordable or unavailable and the health facilities inaccessible. Similarly, some of these plants like V.
References (22)
- et al.
Interactions of atovaquone with other antimalarial drugs against Plasmodium falciparum in vitro
Experimental Parasitology
(1995) - et al.
The effect of artesunate combined with standard antimalarials against chloroquine sensitive and chloroquine resistant strains of Plasmodium falciparum in vitro
Transactions of Royal Society of Tropical Medicine and Hygiene
(1999) - et al.
Screening Tanzanian medicinal plants for antimalarial activity
Acta Tropica
(1994) - et al.
Antiplasmodial activity of four Kenyan medicinal plants
Journal of Ethnopharmacology
(1997) - et al.
Medicinal plants used to treat malaria in Madagascar
Journal of Ethnopharmacology
(1992) A method for testing for synergy with any number of agents
Journal of Infectious Diseases
(1978)- et al.
Quantitative assessment of antimalarial activity in vitro by semi-automated microdilution technique
Antimicrobial Agents and Chemotherapy
(1979) - et al.
Activity of pyronaridine and mepacrine against twelve strains of Plasmodium falciparum in vitro
Journal of Antimicrobial Chemotherapy
(1996) - et al.
Tanzanian medicinal plants used traditionally for the treatment of malaria: in vivo antimalarial and in vitro cytotoxic activities
Phytotherapy Research
(1995) - et al.
Medicinal plants in the fight against leishmaniasis
Parasitology Today
(1994)
Brine shrimp: a convenient general bioassay for active plant constituents
Planta Medica
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