1997 Volume 45 Issue 12 Pages 2034-2038
Following the characterization of gymnemosides-a and -b, new triterpene glycosides, gymnemosides-c, -d, -e, and -f, were isolated from the leaves of Gymnema (G.) sylvestre R. BR. Their chemical structures were elucidated on the basis of chemical and physicochemical evidence as follows : 21-O-benzoyl-28-O-acetylgymnemagenin 3-O-β-D-glycopyranosiduronic acid (gymnemoside-c), 23-O-[β-D-xylopyranosyl (1→6)-β-D-glucopyranosyl (1→6)-β-D-glucopyranosyl] gymnestrogenin (gymnemoside-d), 23-O-[β-D-xylopyranosyl (1→6)β-D-glopyranosyl (1→6)-β-D-glucopyranosyl]-28-O-[β-D-glucopyranosyl (1→6)-β-D-glyucopyranosyl] 23-hydoxylongispinogenin (gymnemoside-e), 23-O-[β-D-xylopyranosyl (1→6)-β-D-glucopyranosyl (1→6)-β-D-glucopyranosyl]-28-O-[β-D-glucopyranosyl (1→6)-β-D-glucopyranosyl] 3β, 16β, 23, 28-tetrahydroxyolean-18-ene (gymnemoside-f). The inhibitory effects of gymnemosides-c, -d, -e, and -f and principal triterpene glycosides from G. sylvestre on glucose uptake in rat small intestinal fragments were examined, and glymnemic acids II, III, and IV, gymnemasaponin V, and gymnemoside-f were found to exhibit the inhibitory activity.
