Antiproliferative Prenylated Stilbenes and Flavonoids from Macaranga alnifolia from the Madagascar Rainforest,1

Bioassay-guided fractionation of an extract of the fruit of Macaranga alnifolia from Madagascar led to the isolation of four new prenylated stilbenes, schweinfurthins E-H (1-4), and one new geranylated dihydroflavonol, alnifoliol (5). The known prenylated stilbene vedelianin (6) and the known geranylated flavonoids bonanniol A (7), diplacol (8), bonannione A (9), and diplacone (10) were also isolated. All 10 compounds were tested for antiproliferative activity in the A2780 human ovarian cancer cell line assay. Vedelianin (IC50 = 0.13 microM) exhibited the greatest activity among all isolates, while schweinfurthin E (IC50 = 0.26 microM) was the most potent of the new compounds.