New minor spirostanol glycosides from Helleborus thibetanus

Phytochemical reinvestigation of the dried roots and rhizomes of Helleborus thibetanus afforded four new minor spirostanol glycosides (1–4) and four known spirostanol glycosides (5–8). Their structures were determined on the basis of spectroscopic analyses, including 1D and 2D NMR experiments, together with HR-ESI-MS and IR measurements and the results of acid hydrolysis.