Oxidation of 9-β-d-ribofuranosyl uric acid by one-electron oxidants versus singlet oxygen and its implications for the oxidation of 8-oxo-7,8-dihydroguanosine

Uric acid, a cellular antioxidant, undergoes oxidation in the presence of one-electron oxidants as well as singlet oxygen. In the present work, the oxidation pathways and products formed from oxidation of the uric acid nucleoside are compared to the more commonly studied uric acid free base. A wider distribution of products, including allantoin, urea, caffolide, and 5-carboxamido-5-hydroxyhydantoin nucleosides, are formed when the N9 position of uric acid is glycosylated. The oxidation pathways share some features in common with the oxidation of 8-oxo-7,8-dihydroguanosine, but the additional spectrum of products implies that the combination of oxidative and deaminative damage to guanosine may lead to a more complex set of DNA lesions than originally described.