Nitric oxide (NO) is recognized as a mediator and regulator of inflammatory responses. Rengyolone, a cyclohexylethanoid isolated from the fruits of Forsythia koreana, exhibits anti-inflammatory activity with unknown mechanism. In this study, we found that rengyolone has a strong inhibitory effect on the production of nitric oxide (NO) and tumor necrosis factor-α (TNF-α). Rengyolone also inhibited inducible nitric oxide synthase (iNOS) gene expression and cyclooxygenase 2 (COX-2) by lipopolysaccharide (LPS). In order to explore the mechanism responsible for the inhibition of iNOS gene expression by rengyolone, we investigated its effect on LPS-induced nuclear factor-κB (NF-κB) activation. The LPS-induced DNA binding activity of NF-κB was significantly inhibited by rengyolone, and this effect was mediated through inhibition of the degradation of inhibitory factor-κBα and phosphorylation of p38 MAP kinase. Furthermore, rengyolone suppressed the expression of ICE protein in IL-1β-treated D10S cells. Taken together, these results suggest that rengyolone attenuates the inflammation through inhibition of NO production and iNOS expression by blockade of NF-κB and p38 MAPK activation in LPS-stimulated RAW 264.7 cells.
Bibliographical noteFunding Information:
This research was supported by a grant from the Plant Diversity Research Center of the 21st Century Frontier Research Program funded by the Ministry of Science and Technology (MOST) of the Korean government.
All Science Journal Classification (ASJC) codes