Mechanism of DNA damage induced by bromate differs from general types of oxidative stress

A representative reactive oxygen species (ROS), hydroxyl radical (OH), is a highly reactive species and induces DNA backbone breakage. OH also oxidizes every DNA base. The interaction of OH with guanine leads to the generation of not only piperidine-resistant 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) but also various piperidine-labile products. On the other hand, potassium bromate (KBrO3) induces specific formation of 8-oxodG in the presence of SH compounds, such as glutathione (GSH) and cysteine (Cys). GSH/Cys reduces KBrO3 (BrO3−) to BrO2, which abstracts one electron from guanine. The one-electron oxidation of guanine may yield cation radicals followed by the reaction with a water molecule, leading to 8-oxodG formation. Therefore, mechanism of bromate-induced oxidative DNA damage is different from general types of oxidative stress such as OH.