Antioxidant properties of aspirin: Characterization of the ability of aspirin to inhibit silica-induced lipid peroxidation, DNA damage, NF-kappa B activation, and TNF-alpha production

Electron spin resonance (ESR) was used to investigate the reaction of aspir in toward reactive oxygen species, such as hydroxyl radicals ((OH)-O-.), su peroxide radicals (O-2(-)) and H2O2. The Fenton reaction (Fe(II) + H2O2 --- > FE(III) + (OH)-O-. + OR) was used as a source of (OH)-O-. radicals. The r esults show that aspirin is an efficient (OH)-O-. radical scavenger with a reaction rate constant of k = 3.6 x 10(10) M(-1)sec(-1), which is faster th an several well established antioxidants, such as ascorbate, glutathione an d cysteine. However, aspirin is not a good scavenger for O-2(-) or H2O2. Th rough its antioxidant property, aspirin exhibited a protective effect again st silica-induced lipid peroxidation and DNA strand breakage. Aspirin also inhibited the activation of nuclear transcription factor-kappa b induced by silica, lipopolysaccharide or the transition metal, Fe(II), as demonstrate d by electrophoretic mobility shift assay. The results show that aspirin fu nctions as an antioxidant via its ability to scavenge (OH)-O-. radicals. Th is antioxidant property may explain some of its various physiological and p harmacological actions.