title: Reduction of iodonitrotetrazolium violet by superoxide radicals.
abstract: p-Iodonitrotetrazolium (2-(4-iodophenyl-3-(4-nitrophenyl)- 5-phenyltetrazolium; INT) was reduced to a water-soluble product with an absorbance maxima at about 505 nm (reddish pink) by superoxide anion (O2-.) generated by xanthine/xanthine oxidase. The rate of INT reduction was linearly related to the xanthine oxidase activities, and was inhibited by superoxide dismutase. The soluble product may further be converted to an insoluble product, presumably nonionic formazan, with an absorbance maxima of 490 nm (purplish), under certain conditions, and the rate of the formazan formation depended on pH and protein concentration.
authors.affiliation: Chemistry Department, Cleveland State University, Ohio 44115.
authors.forename: J J
authors.initials: JJ
authors.lastname: Podczasy
authors.forename: R
authors.initials: R
authors.lastname: Wei
mesh_terms: D005609:Free Radicals; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010084:Oxidation-Reduction; D011506:Proteins / Q000494:pharmacology; D013053:Spectrophotometry; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism; D013778:Tetrazolium Salts / Q000378:metabolism; D019820:Xanthine; D014969:Xanthine Oxidase / Q000378:metabolism; D014970:Xanthines / Q000378:metabolism
chemical_list: D005609:Free Radicals; D011506:Proteins; D013778:Tetrazolium Salts; D014970:Xanthines; D013481:Superoxides; C013574:iodonitrotetrazolium; D019820:Xanthine; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase