Activity of extracts of Kigelia pinnata against melanoma and renal carcinoma cell lines.

Serial dilutions of standardised water, ethanol, and dichloromethane extracts of the stembark and fruits of Kigelia pinnata were tested for their growth inhibitory effects against four melanoma cell lines and a renal cell carcinoma line (Caki-2) using two different (MTT and SRB) assays. Lapachol, a possible constituent of these extracts, together with known therapeutic antineoplastic agents, was also tested in the same way. The IC50 of each extract was measured after extracts were diluted to 100 micrograms/ml in 1% ethanol or water. Significant inhibitory activity was shown by the dichloromethane extract of the stembark and lapachol (continuous exposure). Moreover, activity was dose-dependent, the extract being less active after 1 h exposure. Chemosensitivity of the melanoma cell lines to the stembark was greater than that seen for the renal adenocarcinoma line. In marked contrast, sensitivity to lapachol was similar amongst the five cell lines. Lapachol was not detected in the stembark extract.