Screening extracts of Madagascan plants in search of antiplasmodial compounds

One hundred and ninety plants, of which 51 are used to treat malaria in traditional medicine, were collected in five different ecosystems of Madagascar for a screening programme devoted to the search of naturally-occurring antimalarial compounds. Thirty-nine plants, of which 12 are used as herbal antimalarials, were found to display in vitro activity against Plasmodium falciparum with a median inhibitory concentration (IC50) lower than 5 microg/ml while 9 had an IC50 ranging from 5 to 7.5 microg/ml. Seventeen of them exhibited cytotoxic effects on murine P388 leukemia cells with an IC50 < 10 microg/ml. The biological activities were mostly located in the ethyl acetate fractions. Bioassay-directed fractionation is underway to isolate the active constituents.