8-Hydroxy-2'-deoxyguanosine formation and DNA damage induced by sulfur trioxide anion radicals

The 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation and DNA damage by sulfur trioxide anion radicals (SO3.-) were investigated using ESR spin trapping, HPLC, and electrophoretic assays. Sulfite (SO3(2-) autoxidation generated both hydroxyl (.OH) and SO3.- radicals. Oxidation of SO3(2-) by chromium (VI) generated only SO3.- with much enhanced yield. Incubation of 2'-deoxyguanosine (dG) with SO3(2-) generated 8-OHdG albeit at low yield. Chromium (VI) enhanced the yield four-fold. Electrophoretic assays showed that SO3.- radicals generated by chromium (VI) oxidation of SO3(2-) caused DNA double strand breaks. The results demonstrate that SO3.- radicals are capable of causing dG hydroxylation and DNA double strand breaks.