Neougonin A Inhibits Lipopolysaccharide-Induced Inflammatory Responses via Downregulation of the NF-kB Signaling Pathway in RAW 264.7 Macrophages.

Neougonin A is a prenylated flavonoid isolated from the whole plants of Helminthostachys zeylanica (Ophioglossaceae), which was usually used as traditional Chinese herbal medicine for the treatment of fever and inflammation. In this study, the pharmacological effects and underlying molecular mechanisms of neougonin A on lipopolysaccharide (LPS)-induced inflammatory responses were investigated. We observed that neougonin A reduced the production of inflammatory mediators (TNFα, PGE2, NO, IL-1β, and IL-6; P < 0.001) and inflammation-related proteins (iNOS and COX-2) induced by LPS in murine macrophage RAW 264.7 cells. Furthermore, Western blot and immunofluorescence analysis indicated that neougonin A could inhibit the phosphorylation of IkBα and block the translocation of NF-kB/p65 into the nucleus even at 1.25 μM (P < 0.05), but have no effect on JNK, ERK1/2, and p38MAPK phosphorylation. It was suggested that the anti-inflammatory actions of neougonin A might be due to the downregulation of TNFα, IL-1β, IL-6, NO, and PGE2 via the suppression of NF-kB signal transduction pathway.