Radiation-induced hydroxylation of thymine promoted by electron-affinic compounds

The effect of 20 electron-affinic compounds including nitroimidazoles, nitrofurans, nitrobenzenes, and quinones on the γ-radiation-induced reaction of thymine in aqueous solution was studied under deaerated and N2O-saturated conditions. The formation of thymine glycol was remarkably promoted by the addition of electron-affinic compounds. Irrespective of structures of the electron-affinic compounds, the G-value of thymine glycol increased in sigmoidal form with increasing one-electron reduction potential of the electron-affinic compounds, attaining ultimate values of ca. 1.1 and 1.8 in deaerated and N2O-saturated solutions respectively. Results agree with one-electron oxidation of the hydroxythymol radical, produced by the reaction of thymine with radicalOH, to the corresponding cation by electron-affinic compounds. (author)