Tangeretin Inhibits Oxidative Stress and Inflammation via Upregulating Nrf-2 Signaling Pathway in Collagen-Induced Arthritic Rats

Background/Aims: Tangeretin (TAN), a major phytochemical in tangerine peels and an important Chinese herb, has multiple biological properties, especially antioxidative and anti-inflammatory effects. However, the mechanisms remain unclear. Based on these findings, the aim of the present study was to assess the antioxidant and anti-inflammatory properties of TAN in bovine type II collagen-induced arthritis rats. Methods: TAN (50 mg/kg) was given orally once daily for 14 days. The effects of treatment were evaluated by biochemical assay (articular elastase, myeloperoxidase, end products of lipid peroxidation [MDA], antioxidant enzyme, such as superoxide dismutase, catalase, glutathione), nitric oxide, and inflammatory cytokines (interleukin-1 beta [IL-1 beta], IL-10, tumor necrosis factor-alpha [TNF-alpha], interferon-gamma [IFN-gamma], and prostaglandin E2 [PGE2]). The protective effects of TAN against rheumatoid arthritis (RA) were evident from the decrease in arthritis scoring. Furthermore, the Nrf-2 signaling pathway was assessed to illustrate the molecular mechanism. Results: TAN had therapeutic effects on RA by decreasing the oxidative stress damage and regulating inflammatory cytokine expression, including suppression of the accumulation of MDA products, decreasing the IL-1 beta, TNF-alpha, IFN-gamma, and PGE2 levels, enhancing the IL-10 and the activity of antioxidant enzymes, which was through upregulating Nrf-2 signaling pathway. Conclusion: TAN might have potential as a therapeutic agent for the treatment of RA.