Effects of major dietary antioxidants on inflammatory markers of RAW 264.7 macrophages

Oxidative stresses are involoved in the process of chronic inflammatory diseases. The objective of this study was to evaluate and compare the anti-inflammatory activity of major dietary antioxidants. Murine RAW264.7 macrophages (4 X 10(6) cells) were incubated in DMEM containing 10% FBS supplemented with 5 to 20 muM of alpha-tocopherol, beta-carotene or quercetin for 24 hrs, and then treated with LPS for 16hrs. The medium was collected to measure TNF-alpha, IL-6, PGE(2) and nitrite. Expressions of cyclooxygenase-2(COX-2) and inducible nitric oxide synthase(iNOS) were determined using the harvested cells. Results indicate that TNF-alpha and IL-6 accumulations were significantly reduced by 5 to 20 muM quercetin treatment, and 20 muM of alpha-tocopherol treatment. Nitrite release was significantly reduced by 5 muM quercetin treatment. However, PGE(2) accumulation was not affected by any of the antioxidants used. Expressions of COX-2 and iNOS were effectively reduced by 5 muM quercetin treatment. These findings indicate that dietary antioxidants possess significant anti-inflammatory activities, and quercetin is the most potent antioxidant.