The anti-glycative potentials of pregnane glycosides from Gymnema sylvestre

Gymnema sylvestre is known for its potent antidiabetic activity. Phytochemical investigations of this plant led to the isolation of three new pregnane glycosides, gymnepregosides R-T (1-3) and four known analogues, 12β-acetyloxy-3β,8β,14β,17β-tetrahydroxypregn-5-en-20-one 3-O-β-D-glucopyranosyl-(1→4)-6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandropyranosyl-(1→4)-β-D-cymaropyranosyl-(1→4)-β-D-cymaropyranoside (4), 12-O-(E)-cinnamoylgymnepregoside F (5), gymnepregoside F (6), and stephanoside I (7). Their structures were identified based on spectroscopic evidence and compared with those reported in the literature. All compounds were evaluated for antiglycative inhibitory activity. Compounds 1, 3, 5, and 6 showed the inhibitory effect on BSA-MGO formation ranging from 6.0 to 8.8 % at the concentrations of 400 μM. Compounds 1 and 2 showed significant breaking properties on MGO-AGE-protein crosslink with percent modification ranging from 54.6 to 58.4 %. Notably, a novel AGEs inhibitor (1) may inhibit the formation and accumulation of MGO-AGEs and protect cells from MGO-AGEs cross-linking damage.