Octanorcucurbitane Triterpenoids Protect against tert-Butyl Hydroperoxide-Induced Hepatotoxicity from the Stems of Momordica charantia

Four novel octanorcucurbitane triterpenes, octanorcucurbitacins A-D (1-4), together with one known octanorcucurbitane triterpene, kuguacin M (5), were isolated from the methyl alcohol extract of the stems of Momordica charantia. Their structures were elucidated on the basis of extensive spectroscopic analyses. Compound 3 inhibited tert-butyl hydroperoxide (t-BHP)-induced hepatotoxicity against HepG2 cells.