Cytotoxic Guaianolide Sesquiterpenoids from .

Twelve guaianolide-type sesquiterpene oligomers with diverse structures were isolated from the whole plants of , including a novel trimer () and two new dimers (, ). The chemical structures of the new compounds were elucidated through spectroscopic data interpretation and computational calculations. Ainsfragolide () is an unusual guaianolide sesquiterpene trimer generated with a novel C-C linkage at C-C, which may be biosynthesized prospectively through a further Michael addition. Cytotoxicity results showed that ainsfragolide () was the most potent compound against five cancer cell lines with IC values in the range of 0.4-8.3 μM.