New cucurbitane triterpenoids with cytotoxic activities from Hemsleya penxianensis.

Seven new cucurbitane triterpenoids, Pengxianencins A-G (1-7) including one alkaloid, were isolated from the ethanol extract of the tubers of Hemsleya penxianensis. Their structures were elucidated on the basis of extensive spectroscopic data, including 1D and 2D NMR spectra as well as HR-ESI-MS. The evaluation of inhibition activity against human Hela, MCF-7, and A-549 cell lines showed that compounds 1, 4, 6, 7 have different levels of cytotoxic activities, with IC50 values ranging from 1.67 to 45.28μM.