Hydroxyl and one-electron oxidation mediated reactions of the purine bases of DNA and model compounds: Mechanistic aspects

A large body of information is now available on the early events involved in the radiation-induced decomposition of DNA and related compounds in both aqueous solutions and in the solid state. However, despite many efforts devoted to the identification of radiation-induced DNA modifications in the past two decades there is still a paucity of data on the final decomposition products which arise form the fate of initially generated DNA purine radicals, at least, in aqueous aerated solutions. One major exception deals with the characterization of 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxodG) within isolated and nuclear DNA upon exposure to ionizing radiation. It should be noted that the biological significance of 8-oxodG 6 as inferred from comprehensive DNA repair and mutagenic studies has been recently assessed. The present survey focuses on recent mechanistic aspects of the decomposition of the guanine moiety of DNA and model compounds as the result of hydroxyl radical and one-electron oxidation reactions in aerated aqueous solutions. In addition, a model system aimed at explaining the radiation-induced formation of DNA-protein crosslinks in aerated aqueous solution is presented