Steroids from the rhizome of Anemarrhena asphodeloides and their cytotoxic activities.

Cancer remains a major killer worldwide. To search for novel naturally occurring compounds that are cytotoxic to cancer cells to be used as lead structures for drug development, five new steroids (1-5) along with seven known ones (6-12) were isolated from the rhizome of Anemarrhena asphodeloides Bge. Their structures were established by detailed spectral studies, including 1D-NMR, 2D-NMR, HR-ESI-MS and by comparison with literature data. These compounds exhibited different levels of growth inhibition against A549, HepG2, Hep3B, Bcap37 and MCF7 cell lines in vitro. Compounds 9, 10 and 11 showed potent inhibitory against all the tested cell lines with IC50 values ranging from 0.35±0.15 to 25.53±0.31μM. The three compounds displayed stronger inhibitory activities against A549, HepG2 and Hep3B cell lines compared with the positive control 5-fluorouracil. The experimental data obtained permit us to identify the roles of the sugar moieties, hydroxyl group, double bond and F-ring with regard to their cytotoxic activities.