Antimalarial activity of crude extracts from nine African medicinal plants.

An ethnobotanical study was conducted in Comores (Ngazidja) about plant species used traditionally for the treatment of various diseases, including malaria. Antimalarial activity of 76 vegetal extracts obtained from 17 species traditionally used to treat malaria symptoms, was evaluated in vitro using Plasmodium falciparum chloroquine-resistant strain (W2). Antiproliferative activity was evaluated on human monocytic THP1 cells and the selectivity index of the plant extracts was calculated. The results showed that 10 plant extracts had a moderate activity (5<IC(50)< or =10 microg/ml), and 6 a good in vitro activity with IC(50) value < or =5 microg/ml. The highest antiplasmodial activity was found for the MeOH/H(2)O leaves extract of Flueggea virosa (Roxb. Ex Willd.) Voigt subsp. virosa (Euphorbiaceae) (IC(50)=2 microg/ml), for roots decoction of Flueggea virosa (IC(50)=3 microg/ml) and for chloromethylenic roots extract of Vernonia colorata (Willd.) Drake subsp. grandis (DC.) C. Jeffrey (Asteraceae) (IC(50)=3 microg/ml). Three other extracts showed moderate antiplasmodial activity (IC(50)<5 microg/ml): Vernonia colorata (aerial part), Piper capense L.f. (Piperaceae), and Leptadenia madagascariensis Decne (Asclepiadaceae) chloromethylenic extracts (IC(50)=6 microg/ml; 7 microg/ml and 9 microg/ml, respectively). All the plants tested displayed a low cytotoxicity on THP1 cells.