Studies on the Constituents of Asclepiadaceae Plants. LXII. The Structures of Two Glycosides, Cynafoside-A and -B, with a Novel Sugar Chain Containing a Pair of Optically Isomeric Sugars, D- and L-Cymaroses, from Cynanchum africanum R. BR.

Abstract

Two glycosides named cynafoside-A (1) and -B (2) were isolated from Cynanchum africanum R. BR. (Asclepiadaceae) which is toxic to stock in South Africa. Their structures were determined on the basis of spectral and chemical evidence, and are unusual in that they include both D-and L-cymaroses in the sugar chain.