Saponins from roots of Platycodon grandiflorum. Part 2. Isolation and structure of new triterpene glycosides

Abstract

Seventeen new saponins (2)–(18) have been isolated from the roots of Platycodon grandiflorum A. DC. and their structures determined by comparison of their ¹³C n.m.r. signals with those of known prosapogenins (19)–(26) and of the sugar chain at C-28 in platycodin-D (1). Eight of these saponins were found to have an O-acetyl group which migrated both readily and reversibly between the 2-O- and 3-O-positions of the rhamnose moiety in their sugar chain.