Bioactive ent-kaurene diterpenoids from Annona senegalensis.

Activity-guided fractionation of the stem bark of Annona senegalensis gave four bioactive ent-kaurenoids (1-4). Compound 2 showed selective and significant cytotoxicity for MCF-7 (breast cancer) cells (ED50 1.0 microgram/mL), and 3 and 4 exhibited cytotoxic selectivity for PC-3 (prostate cancer) cells but with weaker potencies (ED50 17-18 micrograms/mL). The structure of the new compound, 3, was deduced from spectral evidence.