Three new steroidal saponins from Helleborus thibetanus

Three new steroidal saponins including two spirostanol glycosides (1-2) and one furostanol glycoside 1-sulphate (3) were isolated from the dried roots and rhizomes of Helleborus thibetanus. Structures of the compounds were determined on the basis of extensive use of 1-D and 2-D NMR experiments, together with HR-ESI-MS and IR measurements, as well as the results of acid hydrolysis. Compounds 1-2 represented steroidal saponins with an unusual substitution pattern, which possessed a double bond at C-25 and were glycosylated at 1-OH.