Brine shrimp toxicity and antiplasmodial activity of five Kenyan medicinal plants

The organic extracts of leaves and roots of five plants used for treating malaria in Central, Nairobi and Rift Valley Provinces, Kenya were tested for brine shrimp lethality and in vitro antiplasmodial activity against chloroquine sensitive and resistant strains of Plasmodium falciparum. Of the plants tested, 60% were toxic to the brine shrimp (LC(50)<30 microg/ml) and eight out of ten plant parts (80%) showed in vitro antiplasmodial activity (IC(50)<50 microg/ml). Among the extracts screened, the leaves of Cyathula polcephala had the highest toxicity to the brine shrimp (LC(50)=2.9 microg/ml) while the leaves of Pentas longiflora had the best antiplasmodial activity (IC(50)=11. /ml). The plant extracts with low IC(50) values are potential sources for novel antiplasmodial compounds.