Three new sesquiterpene lactone dimers from Carpesium faberi

- Three new 2,4-linked sesquiterpene lactone dimers (SLDs) have been isolated from Carpesium faberi.
- Compound 3 was a modified Diels-Alder adduct, characteristic by a 1′β-OH and a Δ5′(6′) double bond.
- Compounds 1 and 2 showed potent cytotoxicity against human leukemia (CCRF-CEM) cells.

Three new 2,4-linked sesquiterpene lactone dimers (SLDs), faberidilactones F-H (1-3), have been isolated from Carpesium faberi. Unlike 1 and 2, 3 was a modified Diels-Alder adduct, characteristic by a 1′-OH and a Δ5′(6′) double bond. Furthermore, the relative configuration of 1′-OH in 3 was assigned as β-configuration by comparison the experimental NOESY data with those of its two possible epimers. The exo/endo stereochemistry of 1-3 was determined by the spectrographic features of 2,4-linked SLDs that we discovered in our previous works. Compounds 1 and 2 showed potent cytotoxicity against human leukemia (CCRF-CEM) cells with IC50 value of 5.62 and 3.74 μM, respectively.