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DNA oxidation is the process of oxidative damage of deoxyribonucleic acid. As described in detail by Burrows et al., 8-oxo-2'-deoxyguanosine is the most common oxidative lesion observed in duplex DNA because guanine has a lower one-electron reduction potential than the other nucleosides in DNA. The one electron reduction potentials of the nucleosides are guanine 1.29, adenine 1.42, cytosine 1.6 and thymine 1.7. About 1 in 40,000 guanines in the genome are present as 8-oxo-dG under normal conditions. This means that >30,000 8-oxo-dGs may exist at any given time in the genome of a human cell. Another product of DNA oxidation is 8-oxo-dA. 8-oxo-dA occurs at about 1/10 the frequency of 8-oxo-dG. The reduction potential of guanine may be reduced by as much as 50%, depending on the particular neighboring nucleosides stacked next to it within DNA.
Excess DNA oxidation is linked to certain diseases and cancers, while normal levels of oxidized nucleotides, due to normal levels of ROS, may be necessary for memory and learning.