RESUMO
The antiplasmodial, anti-trypanosomal and anti-leishmanial activity of 25 plant extracts obtained from seven Tanzanian medicinal plants: Annickia (Enantia) kummeriae (Annonaceae), Artemisia annua (Asteraceae), Pseudospondias microcarpa (Anacardiaceae), Drypetes natalensis (Euphorbiaceae), Acridocarpus chloropterus (Malpighiaceae), Maytenus senegalensis (Celastraceae) and Neurautanenia mitis (Papilonaceae), were evaluated in vitro against Plasmodium falciparum K1, Trypanosoma brucei rhodesiense STIB 900 and axenic Leishmania donovani MHOM-ET-67/82. Out of the 25 extracts tested, 17 showed good antiplasmodial activity (IC50 0.04-5.0 microg/ml), 7 exhibited moderate anti-trypanosomal activity (IC50 2.3-2.8 microg/ml), while 5 displayed mild anti-leishmanial activity (IC50 8.8-9.79 microg/ml). A. kummeriae, A. annua, P. microcarpa, D. natalensis, M. senegalensis and N. mitis extracts had good antiplasmodial activity (IC50 0.04-2.1 microg/ml) and selectivity indices (29.2-2,250 microg/ml). The high antiplasmodial, moderate anti-trypanosomal and mild anti-leishmanial activity make these plants good candidates for bioassay-guided isolation of anti-protozoal compounds which could serve as new lead structures for drug development.