Effect of Purine Nucleoside Phosphates on OH-Radical Generation by Reaction of Fe2+ With Oxygen

Abstract

The influence of various purine nucleotides, nucleosides and nucleoside phosphates on the generation of OH-radicals by the reaction of Fe2+ with oxygen was investigated. Coumarin-3-carboxylic acid was used as a fluorescent detector of OH.. Nucleoside triphosphates caused the enhancement of OH. production due to chelation of ferrous ion by the phosphate moiety. About 30% of produced OH. are intramolecularly scavenged by the nucleoside moiety of the chelator molecule. Nucleoside diphosphates cause a slight enhancement of OH. yield. Nucleotides, nucleosides and nucleoside monophosphates decrease the OH. production. Rate constants of reaction between OH. and nucleoside derivatives were determined from the competitive scavenging of OH radicals, produced by oxidation of Fe(2+)-EDTA complex. Derivatives of guanosine and xanthine are more efficient scavengers in comparison to adenine and inosine. Phosphate groups do not affect the constant of reaction of nucleoside with OH.. Our results suggest that the yield of OH. in the presence of the nucleotide derivatives is determined by chelation of ferrous with polyphosphates and preferential OH. scavenging by the organic portion of molecule. We propose that the generation of active oxygen intermediates in the reaction between nucleoside triphosphate complexes of iron and molecular oxygen is involved in iron-related cellular injury.