2-Amino-8-hydroxy-1H-purin-6(7H)-one, also known as 8-hydroxyguanine or 8-oxoguanine, is a key compound in biochemical research primarily as a biomarker for oxidative DNA damage. It forms via reactive oxygen species-mediated oxidation of guanine in DNA and RNA, serving as an indicator of oxidative stress in cells. Widely used in studies of mutagenesis, carcinogenesis, and aging. Essential in investigating DNA repair mechanisms, such as base excision repair involving enzymes like human 8-oxoguanine DNA glycosylase (OGG1). Commonly employed as an analytical standard in chromatographic and spectrometric methods (e.g., HPLC, LC-MS/MS) for quantifying 8-oxoguanine levels in biological samples like urine, plasma, and tissues. Its tautomeric forms and reactivity also make it useful in synthesizing modified nucleosides and probes for studying nucleic acid stability and enzyme-substrate interactions.