Hypoglucaemic triterpenoid saponins from Boussingaultiabaselloides

Abstract

New saponins with hypoglucaemic activity (1–4) and momordin Ic (5) have been isolated from the methanolic extract of the leaves of Boussingaultiabaselloides. They were shown by spectroscopy and chemical transformation to be derivatives of 12,20(29)-dien-30-noroleanic acid. Boussingoside A1 (1) exhibits very strong hypoglucaemic activity in rats. Acid hydrolysis of the saponin 1 yielded five transformation products (6–10), though one of them (larreagenin A (6), which has been reported in the literature as a genuine plant metabolite) is considered to be an artifact formed by the acid treatment. Keywords: Boussingaultiabaselloides, Basellaceae, boussingosides, triterpenoid saponins, hypoglucaemic activity.