A new major triterpene saponin from the roots of Cucurbita foetidissima

Foetidissimoside B (1), a novel triterpene saponin, was isolated from the roots of Cucurbita foetidissima. Based on spectroscopic data, especially direct and long-range heteronuclear 2D NMR analysis and on chemical transformations, the structure of 1 was elucidated as 3-O-beta-D-glucuronopyranosyl-echinocystic acid 28-O-beta-D-glucopyranosyl-(1-->3)-beta-D-xylopyranosyl(1-->3)-[beta-D-xylopyranosyl (1-->4)]-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranoside. Compound 1 did not show any ability to potentiate in vitro cisplatin cytotoxicity in a human colon cancer cell line.