Antiplasmodial activity of selected medicinal plants used to treat malaria in Ghana.

The use of medicinal plants for the treatment of diseases including malaria is commonplace in Ghanaian traditional medicine, though the therapeutic claims for most plants remain unvalidated. Antiplasmodial activity of the aqueous extracts and successively obtained petroleum ether, ethyl acetate and methanol fractions of the whole Phyllanthus fraternus plant, the leaves of Tectona grandis, Terminalia ivorensis and Bambusa vulgaris, and roots of Senna siamea were studied against Plasmodium falciparum chloroquine-sensitive 3D7 and chloroquine-resistant W2 strains. The aqueous extracts were assessed against human umbilical vein endothelial cells (HUVECs) for cytotoxicity, and the organic solvent fractions against human O(+) erythrocytes for haemolytic effect. Both extracts and fractions demonstrated antiplasmodial activity to varied extents. The aqueous extract of T. ivorensis was the most active (3D7, IC50 0.64 ± 0.14; and W2, IC50 10.52 ± 3.55 μg/mL), and together with P. fraternus displayed cytotoxicity (CC50 6.25 ± 0.40 and 31.11 ± 3.31 μg/mL, respectively). The aqueous extracts were generally selective for 3D7 strain of P. falciparum (selectivity indexes (SIs) ≥3.48) but only that of S. siamea was selective for the W2 strain (SI > 2.1). The organic solvent fractions also displayed antiplasmodial activity with the methanol fractions of P. fraternus and T. grandis, and the fractions of B. vulgaris showing activity with IC50 below 1 μg/mL against P. falciparum 3D7 strain; some fractions showed haemolytic effect but with low to high selectivity indexes (SI ≥ 4). The results while justifying the traditional use of the plant materials in the treatment of malaria, however, suggest their cautious use.