Two novel sesquiterpene lactones, cytotoxic vernolide-A and -B, from Vernonia cinerea

Abstract

Bioassay-directed fractionation of an ethanolic extract of stems of Vernonia cinerea has resulted in the isolation of two novel sesquiterpene lactones, vernolide-A and -B. Their structures were elucidated on the basis of spectroscopic analysis. Biological evaluation showed that vernolide-A demonstrated potent cytotoxicity against human KB, DLD-1, NCI-661, and Hela tumor cell lines (ED50=0.02, 0.05, 0.53, 0.04 μg/ml for KB, DLD-1, NCI-661, and Hela, respectively); vernolide-B had marginal cytoxicity (ED 50=3.78, 5.88, 6.42 μg/ml for KB, NCI-661, and Hela, respectively). © 2003 Pharmaceutical Society of Japan.