Flowers of Inula japonica Attenuate Inflammatory Responses

ABSTRACT

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), PGE2, TNF-alpha, and IL-6 release, as well as NF-kappa B 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-alpha and IL-6. Furthermore, IFE inhibited the NF-kappa B activation induced by LPS, which was associated with the abrogation of I kappa B-alpha 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-kappa B activation via suppression of I kappa B alpha and MAP kinase phosphorylation in macrophages.