Six New Steroidal Saponins from Helleborus thibetanus

Six steroidal saponins, including five spirostanol glycosides, 1-5, and one furostanol glycoside 1-sulfonate, 6, previously unknown in nature, together with three known compounds, 7-9, were isolated from dried roots and rhizomes of Helleborus thibetanus. Their structures were elucidated by extensive 1D- and 2D-NMR experiments, along with IR and HR-ESI-MS data, as well as the results of acid hydrolysis. Compounds 1-5 possessed a C(25)=C(27) bond and were glycosylated at HO=C(1), which was unusual in steroidal saponins.