Koanolides B-D, new sesquiterpene lactones from Koanophyllon gibbosum

Abstract Three new germacrane-type sesquiterpene lactones, koanolides B–D (1-3) have been isolated from the aerial parts of Koanophyllon gibbosum (Asteraceae), along with the previously reported sesquiterpene lactone koanolide A and the flavonoid eupatorin. The structures of the new compounds were elucidated using spectroscopic and spectrometric data analyses, including 1D and 2D NMR, and by comparison with known spectral data. The antiproliferative activities of the new compounds were evaluated in a panel of six representative human solid tumor cell lines and showed GI50 values ranging from 1.3 to 16 μM for the new molecules.