Mappain, a new cytotoxic prenylated stilbene from Macaranga mappa.

A new prenylated stilbene, mappain (1), was isolated from leaves of Macaranga mappa by bioassay-guided fractionation. The structure was established by application of spectroscopic methods. Mappain is cytotoxic but it appears to be a poor substrate for P-glycoprotein-mediated transport because it is equally potent and effective against the drug-sensitive SK-OV-3 and drug-resistant SKVLB-1 ovarian cancer cell lines, exhibiting an IC(50) value of 1.3 microM in both cases.