Ypsilandrosides C-G, five new spirostanol saponins from Ypsilandra thibetica.

A further phytochemical investigation on the whole plants of Ypsilandra thibetica yielded one sapogenin and 12 spirostanol saponins. Five of these are new compounds, designated as ypsilandrosides C-G (2-6). Their structures were determined by detailed spectroscopic analysis, including extensive 1D and 2D NMR data, and by the result of a hydrolytic reaction. Compounds 2-5 were rare steroidal saponins that an apiofuranosyl unit was directly linked at C-3 of the aglycone. Selected spirostanol saponins (2-6, 9) were tested for their cytotoxic activities against K562, SPC-A-1, BGC-823, Eca-109, and AGS cell lines. Compounds 6 and 9 showed moderate inhibitory activity against all five cell lines. The antifungal properties of the new spirostanol saponins (2-6) against Candida albicans were also determined.