A new triterpenoid saponin, named dumortierinoside A, was isolated from Iso
latocereus dumortieri. The structure was determined as dumortierigenin 3-O-
alpha-L-rhamnopyranosyl (1-2)-beta-D-glucopyranosyl( 1-->2)beta-D-glucurono
pyranoside (1) on the basis of NMR and mass spectroscopy.