Radiation-induced damage to DNA: mechanistic aspects and measurement of base lesions

Emphasis has been placed in the present survey on mechanistic aspects of th e radiation-induced decomposition of the guanine moiety of DNA and model co mpounds. An almost complete description of the radical reactions induced by both OH radicals (indirect effects) and one-electron oxidation (direct eff ects) in aerated aqueous solution is now possible. This was inferred from b oth earliest investigations of the transient radicals of these reactions an d detailed structural determination of the final decomposition products. In formation is also provided on several tandem lesions whose formation result s from one initial radical event involving either the sugar moiety or the b ase residue of nucleosides. It should be noted that there is a paucity of i nformation on the radiation-induced formation of base damage within cellula r DNA. A critical evaluation of the available methods aimed at monitoring t he levels of oxidative base damage to cellular DNA is made in the second pa rt of the review article. (C) 1999 Elsevier Science B.V. All rights reserve d.