Antimalarial activity in crude extracts of Malawian medicinal plants.

Aqueous and organic fractions from Cassia abbreviata, Senna petersiana (both Caesalpiniaceae) and Azanza garckeana (Malvaceae) were tested for in-vitro antimalarial activity against the multi-drug-resistant, Vietnam-Smith strain of Plasmodium falciparum; VI/S. Both roots and leaves from these Malawian medicinal plants were investigated. High activity, with a median inhibitory concentration < 3 micrograms/ml, was seen in the organic fractions of C. abbreviata and S. petersiana, the two species most commonly cited by traditional healers in an ethnobotanical investigation of Malawian antimalarials. Extracts of A. garckeana showed weaker activity. Biologically active compounds have thus been detected within species of the family Caesalpiniaceae. Ethnobotanical investigation appears to be useful in identifying plants with antimalarial activity.