Cytotoxic constituents from the leaves of Jerusalem artichoke (Helianthus tuberosus L.) and their structure-activity relationships

Bioassay-directed phytochemical study of the Jerusalem artichoke (Helianthus tuberosus L.) leaves led to the isolation of a new sesquiterpene lactone of 3-Hydroxy-8 beta-tigloyloxy-1,10-dehydroariglovin (1), ten known sesquiterpene lactones (2-11) and two known flavones (12-13). Their chemical structures were elucidated on the basis of NMR (1D and 2D) and mass spectroscopic analysis. The cytotoxic activities of those compounds were subsequently tested against the MCF-7, A549 and HeLa cancer cells lines. The results indicated that sesquiterpene lactones 1-11 exhibited consistent cytotoxicity against all three cancer cell lines, while flavones 12 and 13 showed selective inhibitory activity against HeLa cell lines. Among them, compound 3 exhibited significant growth inhibitory activity against all three cell lines. The IC50 values of compound 3 against MCF-7, A549 and HeLa were 1.97 +/- 0.04, 7.79 +/- 0.44, 9.87 +/- 0.20 mu g/ml, respectively. In addition, some structure-activity relationships of these sesquiterpene lactones for cytotoxicity were explored and summarized in this study. (C) 2012 Phytochemical Society of Europe. Published by Elsevier B. V. All rights reserved.