Ypsilactosides A and B, Two New C22-Steroidal Lactone Glycosides from Ypsilandra thibetica

Two new C22‐steroidal lactone glycosides, ypsilactosides A (1) and B (2), were isolated from the EtOH extract of the whole plant of Ypsilandra thibetica. Their structures were established as (3β,5α,16β,20S)‐3,16‐dihydroxy‐6‐oxopregnane‐20‐carboxylic acid γ‐lactone 3‐(β‐D‐glucopyranoside) (1) and (3β,16β)‐3,16‐dihydroxypregna‐5,20‐diene‐20‐carboxylic acid γ‐lactone 3‐{O‐α‐L‐rhamnopyranosyl‐(1→4)‐O‐α‐L‐rhamnopyranosyl‐(1→4)‐O‐[α‐L‐rhamnopyranosyl‐(1→2)]‐β‐D‐glucopyranoside} (2) on the basis of extensive spectroscopic analyses and chemical degradations.