Two bioactive pentacyclic triterpene esters from the root bark of Hibiscus syriacus

Two new triterpene caffeates have been isolated from the root bark of Hibiscus syriacus. Their structures were established through various spectral studies as 3beta,23,28-trihydroxy-12-oleanene 23-caffeate (1) and 3beta,23,28-trihydroxy-12-oleanene 3beta-caffeate (2). Compounds 1 and 2 showed lipid peroxidation inhibitory activity and significant cytotoxicity against a panel of human cancer cell lines.