Growth Inhibitory Evaluations of Four Nigerian Medicinal Plants against Cancer Cells, with Active Cytotoxic Fractions from the Leaves of Parquetina Nigrescens

Based on ethnomedicinal applications in treating tumour related ailments, effects of the methanol extracts of Brachystegia eurycoma (leaf and stem bark), Parquetina nigrescens and Struchium sparganophora (leaves) were evaluated on lung cancer cells at concentrations of 1-250 μg/ml. Hexane, dichloromethane and aqueous fractions of P. nigrescens were tested on the cells at concentrations of 1-100 μg/ml. While the extracts of B. eurycoma (leaf) and S. sparganophora did not have effect on the cells at the highest concentration tested, the other plant produced remarkably inhibited growth of the cancer cells at concentration of 100 μg/ml. Fractionation of the methanol extract of P. nigrescens produced an enhanced activity over the crude extract as the dichloromethane fraction exhibited cytotoxic effects at concentration of 50 μg/ml with GI50 of 14 ± 4.0, TGI of 30 ± 2.0 and LC50 of 45 ± 1.0 μg/ml. The overall results showed that the methanol extracts of B. eurycoma (stem bark) and Parquetina nigrescens can be used to prevent the proliferation of lung cancer cells and hence justify the ethnomedicinal uses of the plants in treating tumour related ailments.