Two C21-steroidal glycosides isolated from Cynanchum stauntoi.

Studies on the roots of Cynanchum stauntoi led to the isolation of two C21-steroidal glycosides, formally named stauntosides A and B. Their structures were elucidated on the basis of spectroscopic evidence, especially that from analysis of 2D-NMR spectra. They were found to possess an unusual skeleton and were identified as stauntogenin 3-O-alpha-L-diginopyranosyl-(1-4)-beta-L-cymaropyranosyl-(1- 4)-beta-D- digitoxopyranosyl-(1-4)-beta-D-thevetopyranoside and stauntogenin 3-O-alpha-L-cymaropyranosyl-(1-4)-beta-D-digitoxopyranosyl-( 1-4)-beta-D-3- demethyl-2-deoxy-thevetopyranoside.