Two New Spirostanol Glycosides from the Roots and Rhizomes of Helleborus thibetanus Franch.

Two new spirostanol glycosides, thibetanosides J and K (1 and 2), along with three known ones (3-5) were isolated from the roots and rhizomes of Helleborus thibetanus. Their structures were elucidated by extensive use of spectroscopic techniques and chemical evidence. In this study, compounds 1-5 were evaluated for their cytotoxic activity against HCT116, A549 and HepG2 tumor cell lines. Among them, compound 1 exhibited moderate cytotoxicity against A549 cells (IC50 7.69 +/- 1.13 mu M) and HepG 2 cells (IC50 8.32 +/- 2.63 mu M). Compound 2 exhibited moderate cytotoxicity against HCT116 cells (IC50 20.67 +/- 1.06 mu M).