New hypoglycemic constituents in 'gymnemic acid' from Gymnema sylvestre

Abstract

Investigation of hypoglycemic activity of major saponin constituents from 'gymnemic acid', a crude saponin fraction of G. sylvestre, exposed not only two new saponins, gymnemosides a (1) and b (2), but also gymnemoside b and gymnemic acid V (7) as active principles. Furthermore, an acetyl group linked 16- or 22-hydroxy group in 1 and 2 was found to migrate easily to primary 28- hydroxyl group, while acyl migration from 28-hydroxy group in 3 was little observed.