The antioxidants curcumin and quercetin inhibit inflammatory processes associated with arthritis

Objective: Curcumin and quercetin are antioxidant molecules with anti-proliferative, anti-inflammatory and immunosuppressive activities. The objective of this study was to investigate the inhibitory activity of these agents using four assays of inflammatory aspects of arthritis. Methods: Crystal-induced neutrophil activation was measured by luminol-dependent chemiluminescence. Synoviocyte proliferation was measured by an NITS assay using HIG-82 rabbit synoviocytes in cell culture. Chondrocyte (cultured primary cells) expression of the matrix metalloproteinases collagenase and stromelysin was measured by Northern Blot analysis. Angiogenesis was measured using the chorioallantoic membrane of the chick embryo. Results: Both agents inhibited neutrophil activation, synoviocyte proliferation and angiogenesis. Curcumin strongly inhibited collagenase and stromelysin expression at micromolar concentrations whereas quercetin had no effect in this assay. Conclusion: These studies suggest that curcumin and to a lesser extent quercetin may offer therapeutic potential for the treatment of crystal-induced arthritis or rheumatoid arthritis.