Suppressive Effect of Tomentosin on the Production of Inflammatory Mediators in RAW264.7 Cells

In this study, tomentosin, a sesquiterpene lactone was isolated from Inulae fibs and its biological activities were investigated. The effects of tomentosin on the production of inflammatory mediators as well as on nuclear factor (NF)-kappa B and mitogen-activated protein (MAP) kinase activation were evaluated in RAW264.7 cells. Tomentosin decreased the production of nitric oxide (NO) and prostaglandin E-2 (PGE(2)) by suppressing the protein expression of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2, respectively. Additionally, tomentosin reduced the release of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). Tomentosin not only attenuated lipopolysaccharide (LPS)-induced NF-kappa B activation via the abrogation of inhibitory (I)kappa B alpha degradation and caused a subsequent decrease in nuclear p65 level, but it also suppressed the phosphorylation of MAP kinases (p38 and c-Jun N terminal kinase (JNK)). These results indicate that tomentosin exerts anti-inflammatory activities through the inhibition of inflammatory mediators (NO, iNOS, PGE(2), COX-2, TNF-alpha, and IL-6) by regulating NF-kappa B activation and phosphorylation of p38/JNK kinases in macrophages, thus suggesting that tomentosin could be a potential agent for the treatment of inflammatory diseases.