Twelve guaianolide-type sesquiterpene
oligomers with diverse structures
were isolated from the whole plants of Ainsliaea fragrans, including a novel trimer (1) and two new dimers (2, 3). The chemical structures of the new compounds
were elucidated through spectroscopic data interpretation and computational
calculations. Ainsfragolide (1) is an unusual guaianolide
sesquiterpene trimer generated with a novel C–C linkage at
C2’–C15″, which may be
biosynthesized prospectively through a further Michael addition. Cytotoxicity
results showed that ainsfragolide (1) was the most potent
compound against five cancer cell lines with IC50 values
in the range of 0.4–8.3 μM.