Sesquiterpene lactones with anti-inflammatory and cytotoxic activities from the roots of Cichorium intybus

Cichorium intybus L. (Asteraceae), belonging to the tribe Cichorieae of the family Asteraceae, has a long history as an edible and medicinal food. Sesquiterpene lactones are commonly considered as its major active constituents. In the current study, five unreported sesquiterpene lactones, including one 12,8-guaianolide and four 12,6-guaianolides were isolated from C. intybus roots, as well as 16 known analogues. The planar structures and relative configurations of these compounds were elucidated by extensive spectroscopic analysis. The absolute configurations were determined by the time-dependent density functional theory (TDDFT)-based electronic circular dichroism (ECD) calculation method. Bioassay results showed that seven of the isolates exhibited remarkable NO production inhibitory activity in LPS-stimulated RAW264.7 macrophages, with IC50 values ranging from 1.83 to 38.81 μM. Some of them can significantly decrease the secretion of inflammatory cytokines (TNF-α and IL-6). Cytotoxicity assays demonstrated that intybusins B, as well as four known compounds, displayed obvious inhibitory activities against four human tumor cells, with IC50 values ranging from 9.01 to 27.07 μM.