Saponins from the roots of Zygophyllum gaetulum and their effects on electrically-stimulated guinea-pig ileum

A new ursanolide, 3β-O-α-l-rhamnopyranosyl-(1->2)-O-α-l-arabinopyranosyl-(1->2)-β-d-glucopyranosyl)oxy]-ursan-20β,28-olide, zygophyloside N (1), and three known quinovic acid glycosides were isolated from the methanolic extract of the roots of Zygophyllum gaetulum. The crude extract, some fractions and 3-O-β-d-glucopyranosyl quinovic acid 28-β-d-glucopyranosyl ester, significantly and dose-dependently, are able to reduce the electrically-induced contractions of isolated guinea-pig ileum. The structure of compound (1) was determined, using 1D and 2D NMR techniques.