Anti-inflammatory triterpene saponins of Pithecellobium dulce: characterization of an echinocystic acid bisdesmoside.

A new bisdesmodic triterpenoid saponin, dulcin was isolated from the seeds of Pithecellobium dulce and was identified as 3-O-[beta-D-glucopyranosyl (1-->2)-alpha-L-arabinopyranosyl]- 28-O-[beta-D-xylopyranosyl (1-->6)-beta-D-glucopyranosyl]-echinocystic acid. The known oleanolic acid saponin PE, oleanolic acid 3-O-beta-D-glucopyranosyl (1-->2)-alpha-L-arabinopyranoside was also obtained. The structural features were elucidated by a combination of spectroscopic methods and some chemical transformations.