title: Antioxidant properties of 2-imidazolones and 2-imidazolthiones.
abstract: Uric acid has been postulated to be an important antioxidant and free radical scavenger in humans. Other purines, such as xanthine, that lack an 8-oxo group on the imidazole ring do not show antioxidant properties. For this reason, the antioxidative activities of 2-imidazolones and 2-imidazolthiones were compared to that of uric acid. 2-Imidazolthiones reacted with the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) at rates comparable to those of uric acid and other antioxidants. 2-Imidazolones also reacted with DPPH, although at a much slower rate than the 2-imidazolthiones. The 2-imidazolthiones protected oxyhemoglobin from oxidation to methemoglobin by sodium nitrite; the 2-imidazolones had little effect on the oxidation of oxyhemoglobin by nitrate. Most of the 2-imidazolthiones and 2-imidazolones protected both porcine and bovine erythrocytes from hemolysis by t-butyl hydroperoxide. Although 2-imidazolthiones were more reactive than 2-imidazolones in the assays using DPPH and the oxidation of oxyhemoglobin, both types of compounds may be useful as antioxidants in vivo.
mesh_terms: D000818:Animals; D000975:Antioxidants; D002417:Cattle; D004912:Erythrocytes / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects*; D007093:Imidazoles / Q000494:pharmacology*; D008706:Methemoglobin / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013552:Swine
chemical_list: D000975:Antioxidants; D007093:Imidazoles; D008706:Methemoglobin