Caroguaianolide A-E, five new cytotoxic sesquiterpene lactones from Carpesium abrotanoides L.

Five new guaiane-type sesquiterpene lactones, caroguaianolide A-E (1-5), along with nine known sesquiterpene lactones (6-14) were isolated from the whole plant of Carpesium abrotanoides L. Their structures were elucidated on the basis of spectroscopic date, HRESIMS analysis, and comparison of experimental and calculated ECD data. All isolated compounds (1-14) were tested in vitro for their cytotoxic activities against the MDA-MB-231, HGC-27 cancer cell lines, of which compounds 1-3, 6, 7, 11 and 12 showed significant cytotoxic activities with IC50 values ranging from 2.67 to 12.34 μM.