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 3β,23,28-trihydroxy-12-oleanene 23-caffeate (1) and 3β,23,28-trihydroxy-12-oleanene 3β-caffeate (2). Compounds 1 and 2 showed lipid peroxidation inhibitory activity and significant cytotoxicity against a panel of human cancer cell lines.