Flowers of Inula japonica Attenuate Inflammatory Responses

BACKGROUND The flowers of Inula japonica (Inulae Flos) have long been used in traditional medicine for the treatment of inflammatory diseases. In the present study, we investigated the anti-inflammatory properties of Inulae Flos Extract (IFE). METHODS The anti-inflammatory effects of IFE against nitric oxide (NO), PGE(2), TNF-α, and IL-6 release, as well as NF-κB and MAP kinase activation were evaluated in RAW 264.7 cells. RESULTS IFE inhibited the production of NO and the expression of inducible nitric oxide synthase (iNOS) in LPS-stimulated RAW264.7 cells. In addition, IFE reduced the release of pro-inflammatory cytokines, such as TNF-α and IL-6. Furthermore, IFE inhibited the NF-κB activation induced by LPS, which was associated with the abrogation of IκB-α degradation and subsequent decreases in nuclear p65 and p50 levels. Moreover, the phosphorylation of ERK, JNK, and p38 MAP kinases in LPS-stimulated RAW 264.7 cells was suppressed by IFE in a dose-dependent manner. CONCLUSION These results suggest that the anti-inflammation activities of IFE might be attributed to the inhibition of NO, iNOS and cytokine expression through the down-regulation of NF-κB activation via suppression of IκBα and MAP kinase phosphorylation in macrophages.