Anti-plasmodial activity and toxicity of extracts of plants used in traditional malaria therapy in Meru and Kilifi Districts of Kenya.

Abstract The methanol and aqueous extracts of 10 plant species ( Acacia nilotica , Azadirachta indica , Carissa edulis , Fagaropsis angolensis , Harrissonia abyssinica , Myrica salicifolia , Neoboutonia macrocalyx , Strychnos heningsii , Withania somnifera and Zanthoxylum usambarensis ) used to treat malaria in Meru and Kilifi Districts, Kenya, were tested for brine shrimp lethality and in vitro anti-plasmodial activity against chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum (NF54 and ENT30). Of the plants tested, 40% of the methanol extracts were toxic to the brine shrimp (LD 50 50 N. macrocalyx had the highest toxicity to brine shrimp nauplii (LD 50 21.04 ± 1.8 μg/ml). Methanol extracts of the rest of the plants exhibited mild or no brine shrimp toxicity (LD 50  > 50 μg/ml). The aqueous extracts of N. macrocalyx had mild brine shrimp toxicity (LD 50 41.69 ± 0.9 μg/ml), while the rest were lower (LD 50  > 100 μg/ml). The methanol extracts of F. angolensis and Zanthoxylum usambarense had IC 50 values P. falciparum strains. The results support the use of traditional herbs for anti-malarial therapy and demonstrate their potential as sources of drugs.