Sesquiterpene lactones with potent cytotoxic activities from Vernonia chinensis.

Five new sesquiterpene lactones, namely vernchinilides A-E (1-5), along with five known compounds, 8 beta-(2-methylacryloyloxy)hirsutinolide 13-O-acetate (6), 8 alpha-(2-methylacryloyloxy)-1beta,4beta-epoxy-1alpha-methoxy-13-O-acetate-10 betaH-germacra-5 E,7(11)-dien-12,6-olide (7), 8 beta-(2-hydroxymethylacryloyloxy)hirsutinolide 13-O-acetate (8), 8 alpha-tigloyloxyhirsutinolide 13-O-acetate ( 9) and vernolide-B (10) were isolated from Vernonia chinensis. The structures of these new compounds were elucidated on the basis of spectral data, especially 2D-NMR techniques. Compounds 2, 5 and 6 exhibited potent cytotoxic activities against P-388 and A-549 tumor cell lines.