Sesquiterpene lactones from Elephantopus mollis and their anti-inflammatory activities

Seven sesquiterpene lactones, 8-O-methacryloylelephanpane, 2,4-bis-O-methyl-8-O-methacryloylelephanpane, 4-O-ethyl-8-O-methacryloylelephanpane, 8-O-methacryloylisoelephanpane, 2-O-demethyltomenphantopin C, molephantin A, molephantin B, along with ten known ones, were isolated from Elephantopus mollis (Asteraceae). Their structures were elucidated by extensive analysis of spectroscopic data (IR, UV, HRESIMS, 1D and 2D NMR). The isolates were evaluated for their anti-inflammatory activities on LPS-stimulated RAW 264.7 cells, and all tested compounds exhibited potent anti-inflammatory effects with IC₅₀ values of 0.57 ± 0.17 to 14.34 ± 1.61 μM, except that compound tomenphantopin C exhibited moderate anti-inflammatory activity with IC₅₀ values of 59.97 ± 1.53 μM.