DNA oxidation
![When DNA undergoes oxidative damage, two of the most common damages change guanine to 8-hydroxyguanine or to 2,6-diamino-4-hydroxy-5-formamidopyrimidine.](/Images/godic/202501/09/Guanine_and_2_oxidative_products.svg1503.png")
![Colonic epithelium from a mouse not undergoing colonic tumorigenesis (A), and a mouse that is undergoing colonic tumorigenesis (B). Cell nuclei are stained dark blue with hematoxylin (for nucleic acid) and immunostained brown for 8-oxo-dG. The level of 8-oxo-dG was graded in the nuclei of colonic crypt cells on a scale of 0-4. Mice not undergoing tumorigenesis had crypt 8-oxo-dG at levels 0 to 2 (panel A shows level 1) while mice progressing to colonic tumors had 8-oxo-dG in colonic crypts at levels 3 to 4 (panel B shows level 4) Tumorigenesis was induced by adding deoxycholate to the mouse diet to give a level of deoxycholate in the mouse colon similar to the level in the colon of humans on a high fat diet.[5] The images were made from original photomicrographs.](/Images/godic/202501/09/Colonic_epithelium_mouse_without_tumorigenesis_(A)_and_with_tumorigenesis_(B)._Brown_shows_8-oxo-dG1504.jpg")
DNA oxidation is the process of oxidative damage on Deoxyribonucleic Acid. It occurs most readily at guanine residues due to the high oxidation potential of this base relative to cytosine, thymine, and adenine. It is widely believed to be linked to certain disease and cancers.