In vitro antiprotozoal activities and cytotoxicity of some selected Cameroonian medicinal plants.

Eight extracts from seven selected Cameroonian medicinal plants, traditionally used to treat malaria and other protozoal diseases, were tested in vitro for their antiprotozoal activities against Plasmodium falciparum K1 chloroquine-resistant strain, Leishmania donovani, Trypanosoma cruzi and Trypanosoma brucei rhodesiense, protozoa responsible for malaria, visceral leishmaniasis, Chagas disease and African trypanosomiasis, respectively. The most active extract against Plasmodium falciparum K1 strain and Trypanosoma brucei rhodesiense was the methanolic extract of Albizia zygia (Fabaceae) stem bark with IC(50) values of 1.0 microg/ml and 0.2 microg/ml, respectively. Five extracts showed IC(50) values below 5mug/ml against Leishmania donovani, with the methanolic seed extract of Harungana madagascarensis showing the highest activity, but only the methanolic extract of Albizia zygia showed activity against Trypanosoma cruzi. Cytotoxicity and selectivity indexes were estimated for the most active extracts. The best ratio of cytotoxicity to antiplasmodial activity (SI(a)=14) was established for the methanolic leaf extract of Symphonia globulifera (Clusiaceae), while the methanolic stem bark extract of Albizia zygia showed the best ratio of cytotoxicity to antitrypanosomal activity (SI(b)=22.5).