In vitro anti-plasmodial and in vivo anti-malarial activity of some plants traditionally used for the treatment of malaria by the Meru community in Kenya

Gathirwa, J. , W.; Rukunga, G. , M.; Njagi, E. , N. M.; Omar, S. , A.; Guantai, A. , N.; Muthaura, C. , N.; Mwitari, P. , G.; Kimani, C. , W.; Kirira, P. , G.; Tolo, F. , M.; Ndunda, T. , N.; Ndiege, I. , O.

Extracts of seven medicinal plant species used for treatment of malaria in traditional/cultural health systems of the Ameru people in Kenya were tested in vitro and in vivo against Plasmodium falciparum (D6 and W2 strains) and P. berghei, respectively. Of the plants tested, 28.57% were highly active (IC50 < 10 mu g/ml) and 42.86% moderately active (IC50 10-50 mu g/ml), while 28.57% had weak activity of 50-125 mu g/ml in vitro. The water and methanol extracts of Boscia salicifolia Oliv. and Artemisia afra Jacq. (ex-Willd.) were the most active against both the chloroquine (CQ)-sensitive (D6) and the CQ-resistant (W2) P. falciparum strains. Artemisia afra. and Rhus natalensis Bernh. (ex-Krauss) exhibited the highest parasite clearance and chemo-suppression (> 70%) in vivo (in mice). The plants with high in vitro anti-plasmodial (low IC50 values) and high anti-malarial activity (high chemo-suppression) in vivo are potential sources of novel anti-malarial drugs.