In vitro activity of extracts and isolated polyphenols from West African medicinal plants against Plasmodium falciparum.

The aim of the study was to screen 11 selected traditional medicinal plants from West Africa for their in vitro antiplasmodial activity in order to determine the activity of single and of combination of plant extracts and to examine the activity of isolated pure compounds. Ethanolic and aqueous extracts of the 11 selected plants and pure compounds from Phyllanthus muellerianus and Anogeissus leiocarpus were tested in vitro against Plasmodium falciparum 3D7. Proliferation inhibitory effects were monitored after 48 h. Among the plants and pure compounds investigated in this study, geraniin from P. muellerianus, ellagic, gentisic, and gallic acids from A. leiocarpus, and extracts from A. leiocarpus, P. muellerianus and combination of A. leiocarpus with P. muellerianus affected the proliferation of P. falciparum most potently. Significant inhibitory activity was observed in combination of A. leiocarpus with P. muellerianus (IC(50) = 10.8 μg/ml), in combination of A. leiocarpus with Khaya senegalensis (IC(50) = 12.5 μg/ml), ellagic acid (IC(50) = 2.88 μM), and geraniin (IC(50) = 11.74 μM). In general growth inhibition was concentration-dependent revealing IC(50) values ranging between 10.8 and -40.1 μg/ml and 2.88 and 11.74 μM for plant extracts and pure substances respectively. Comparison with literature sources of in vivo and in vitro toxicity data revealed that thresholds are up to two times higher than the determined IC(50) values. Thus, the present study suggests that geraniin from P. muellerianus; ellagic acid, gallic acid, and gentisic acid from A. leiocarpus; and combination of extracts from A. leiocarpus with either P. muellerianus or K. senegalensis could be a potential option for malaria treatment.