Antiplasmodial activity of triterpenoid isolated from whole plants of Viola genus from South Korea.

Species of the Viola genus, used in traditional medicines for the treatment of parasites, were collected and petroleum ether extract was obtained by sonication. The antiplasmodial activity of petroleum ether extracts was evaluated in vitro against the chloroquine-resistant FcB1 strain of Plasmodium falciparum. Bioactivity-guided fractionation of the petroleum ether extracts of the whole plants of Viola verecunda has led to the isolation of epi-oleanolic acid, a triterpenoid, displaying high antiplasmodial activity (IC(50) 0.18 mug/ml). This is the first report of the isolation and antiplasmodial activity of epi-oleanolic acid from this species.