Cytotoxic dammarane triterpenoids from the hydrolyzate of Gynostemma pentaphyllum

Three undescribed dammarane-type triterpenoids with rare carbon skeletons (1-3), together with one unreported gypenoside (4), were isolated from a acid hydrolysis product of Gynostemma pentaphyllum (Thunb.) Makino. Their molecular structures were elucidated via a combination of spectroscopic and spectrometric data, while the absolute configurations of compounds 1, 2 and 4 were determined by electronic circular dichroism (ECD) analyse. Notably, compounds 1-3 possess a 19(10→1)abeo structural moiety in the A ring. Saponin 4 possesses an unusual cyclopentenone side chain. Compounds 1, 2 and 4 were screened for their antiproliferative effects against HepG2, MCF-7 and DU145 cell lines.