title: Pentoxifylline. A hydroxyl radical scavenger.
abstract: Pentoxifylline (PTX), a tri-substituted purine and xanthine derivative, has been used for several years to improve microcirculation because of its hemorheological properties. PTX has also antifibrotic and anti-inflammatory effects. We studied the reaction of PTX with the hydroxyl radical and superoxide anion. Hydroxyl radical was generated by a mixture of ascorbic acid, H2O2 and Fe(III)-EDTA. We evaluated the iron-dependent degradation of deoxyribose, mediated by hydroxyl radical, in the presence of different concentrations of PTX (from 0.05 to 3 mM), measuring the degradation products of deoxyribose that react with 2-thiobarbituric acid (TBA). The reaction of PTX with hydroxyl radical occurred with a rate constant of (1.1 +/- 0.2) x 10(10) M-1/s. These results support the properties of PTX as a hydroxyl radical scavenger. Some authors verified that PTX decreases the release of superoxide anion from activated neutrophils. We studied the effect of PTX as a scavenger of superoxide generated in vitro by a hypoxanthine-xanthine oxidase system. PTX was not a superoxide anion scavenger in this system.
authors.affiliation: Clínica Dermatológica Universitária, Faculdade de Medicina de Lisboa, Portugal.
authors.forename: J P
authors.initials: JP
authors.lastname: Freitas
authors.forename: P M
authors.initials: PM
authors.lastname: Filipe
mesh_terms: D001205:Ascorbic Acid; D004492:Edetic Acid; D005290:Ferric Compounds; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide; D017665:Hydroxyl Radical; D007502:Iron Chelating Agents; D007700:Kinetics; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology; D010431:Pentoxifylline / Q000494:pharmacology; D013481:Superoxides; D019820:Xanthine; D014969:Xanthine Oxidase / Q000378:metabolism; D014970:Xanthines / Q000378:metabolism
chemical_list: D005290:Ferric Compounds; D016166:Free Radical Scavengers; D007502:Iron Chelating Agents; D014970:Xanthines; D013481:Superoxides; D019820:Xanthine; D017665:Hydroxyl Radical; D004492:Edetic Acid; D006861:Hydrogen Peroxide; D014969:Xanthine Oxidase; C019179:Fe(III)-EDTA; D001205:Ascorbic Acid; D010431:Pentoxifylline