Two new pregnane glycosides from the roots of Cynanchum atratum.

Two new pregnane glycosides, the cynatratosides A and B, were isolated from the roots of Cynanchum atratum, together with six known steroids. The structures of the new isolates were elucidated as glaucogenin A 3-O-β-D-digitoxopyranosyl-(1→4)-O-β-D-oleandropyranoside (cynatratoside A) and amplexicogenin C-3-O-β-D-oleandropyranoside (cynatratoside B) by NMR spectroscopy and acid-catalysed hydrolysis. [ABSTRACT FROM AUTHOR]