Two new C21 steroidal glycosides were isolated from Cynanchum otophyllum Schneid. Their structures were elucidated as qinyangshengenin-3-O-β-d-digitoxopyranoside (1) and rostratamine-3-O-β-d-cymaropyranosyl-(1 → 4)-β-d-digitoxopyranoside (2) on the basis of chemical and spectroscopic methods, including 1D and 2D NMR experiments.
Keywords: 2,6-dideoxypyranose; Asclepiadaceae; C21 steroidal glycosides; Cynanchum otophyllum.