Anti-inflammatory effects of ononin on lipopolysaccharide-stimulated RAW 264.7 cells

Increasing evidence has shown that ononin, a major isoflavone, has anti-inflammatory effects on lipopolysaccharide (LPS)-induced inflammation. However, the molecular mechanisms underlying the anti-inflammatory effects of ononin are still unclear. In the present study, we investigated these effects and the underlying mechanisms of ononin on LPS-induced inflammatory responses. Mouse RAW 264.7 cells were treated with 1μg/mL LPS and 5, 25, 50, 100 or 150μM ononin for 18h. Cell viability was assessed using MTT assays, and the production of nitric oxide (NO), prostaglandin E₂ (PGE₂) and the pro-inflammatory cytokines TNF-α, IL-1β and IL-6 in cultures was examined by Griess and ELISA analyses. qRT-PCR was performed to detect the mRNA expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX-2). Mitogen-activated protein kinases (MAPKs) and nuclear transcription factor Kappa-B (NF-κB) signalling pathway-related proteins were assessed by western blot assays. The results showed that cell viability was not significantly affected by up to 100μM ononin. The production of NO, PGE₂ and the pro-inflammatory cytokines TNF-α, IL-1β and IL-6 in the cultures, the mRNA expression of two major inflammatory mediators, COX-2 and iNOS, and the expression of phosphorylated IκB-α, ERK, JNK, and p38 MAPKs proteins in LPS-treated cells were significantly increased. These changes could be reversed by treatment with ononin in a concentration-dependent manner (P<0.05). The results suggest that ononin has anti-inflammatory effects on LPS-induced inflammatory responses by inhibiting the NF-κB and MAPK pathways and may be a potential treatment for inflammation.