Cadinane sesquiterpenes from the leaves of Eupatorium adenophorum.

Four new cadinane sesquiterpenes (1- 4), including a dimeric cadinane derivative (2) and a peroxide cadinane analogue (3), have been isolated from the leaves of Eupatorium adenophorum. Their structures including absolute configurations were determined on the basis of spectroscopic data interpretation and single-crystal X-ray crystallography. Compound 4 showed in vitro cytotoxicity against the HCT-8, Bel-7402, and A2780 cancer cell lines.