α-Amylase andα-Glucosidase Inhibitory Saponins fromPolyscias fruticosaLeaves

Abstract

Three bisdesmosidic saponins 3-O-[β-D-glucopyranosyl-(1→4)-β-D-glucuronopyranosyl] oleanolic acid 28-O-β-D-glucopyranosyl ester (1), polyscioside D (2), and 3-O-{β-D-glucopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→4)]-β-D-glucuronopyranosyl}oleanolic acid 28-O-β-D-glucopyranosyl-(1→2)-β-D-galactopyranosyl ester (3) were isolated from a methanol extract ofPolyscias fruticosa(L.) Harms leaves. Compound1was obtained as a main constituent and compound3was reported for the first time and named as polyscioside I. Saponin1inhibited porcine pancreasα-amylase and yeastα-glucosidase activities while2and3were inactive. Synergistic inhibitory effect onα-amylase was observed from the combination of low concentrations of1and acarbose. The findings suggest the use ofP. fruticosaand its major saponin1for the prevention and treatment of diabetes and its complications.