Abstract
From the herb of Luffa acutangula ROXB. (Cucurbitaceae), seven oleanane-type triterpene saponins, acutosides A-G, were isolated and their structures were determined.Acutoside A is oleanolic acid 3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranoside. Acutosides B, D, E, F and G have a common prosapogenin structure, acutoside A, and only differ in the structures of the ester-linked sugar moieties. Acutoside B is a 28-O-[O-β-D-xylopyranosyl-(1→4)-O-α-L-rhamopyranosyl-(1→2)-α-L-arabinopyranosyl] ester, D is a 28-O-[O-β-D-xylopyranosyl-(1→3)-O-β-D-xylopyranosyl-(1→4)-O-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl] ester, E is a 28-O-[O-α-L-arabinopyranosyl-(1→3)-O-β-D-xylopyranosyl-(1→4)-O-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl] ester, F is a 28-O-[O-β-D-xylopyranosyl-(1→3)-[O-β-D-xylopyranosyl-(1→4)]-O-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl] ester, and G is a 28-O-[O-β-D-xylopyranosyl-(1→3)-[O-α-L-arabinopyranosyl-(1→3)-O-β-D-xylopyranosyl-(1→4)]-O-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl] ester. Acutoside C is a machaelinic acid (=21β-hydroxyoleanolic acid) saponin having the same sugar moiety as that of acutoside B.
