A new triterpenoid saponin, named Lathyrus saponin (3), was isolated f
rom the whole plant of Lathyrus japonicus Willd. together with two kno
wn saponins, azukisaponins II (1) and V (2), as their methyl esters. T
he structure of 3 was determined to be soyasapogenol B D-glucopyranosy
l(1-->2)-beta-D-glucuronopyranoside on the basis of physicochemical an
d spectroscopic methods.