Lathyrus saponin, a new trisaccharide glycoside from Lathyrus japonicus.

A new triterpenoid saponin, named Lathyrus saponin (3), was isolated from the whole plant of Lathyrus japonicus Willd. together with two known saponins, azukisaponins II (1) and V (2). as their methyl esters. The structure of 3 was determined to be soyasapogenol B 3-0-beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)-beta-D-glu curonopyranoside on the basis of physicochemical and spectroscopic methods.