Two sesquiterpene lactones, arnicolide B and arnicolide C, isolated from Centipeda minima, exert anti-inflammatory effects in LPS stimulated RAW 264.7 macrophages via inactivation of the MAPK pathway

Arnicolide B and arnicolide C are two sesquiterpene lactones isolated and identified from Centipeda minima, but the anti-inflammatory effects and mechanisms of these two compounds have not been reported. In this study, LPS was used to establish RAW 264.7 macrophages inflammatory response model. Griess, ELISA, Western blot were used to investigate the anti-inflammatory effects in vitro and the molecular mechanisms of these two active compounds. The results showed that arnicolide B and arnicolide C could not only inhibit the production of inflammatory mediators NO, PGE₂, TNF-α and IL-6, but also down-regulate the high expression of inflammatory proteins iNOS and COX-2. Furthermore, arnicolide B and arnicolide C inhibited the phosphorylation of ERK, JNK, p38 proteins in the MAPK signaling pathway, but had no effect on the degradation of IκB-α protein and the activation of the NF-κB pathway. As conclusion, these two compounds exert anti-inflammatory effects by inactivation of the MAPK pathway.