8-Oxoguanine

8-Oxoguanine (8-hydroxyguanine, 8-oxo-Gua, or OH⁸Gua) is one of the most common DNA lesions resulting from reactive oxygen species^[2] modifying guanine, and can result in a mismatched pairing with adenine resulting in G to T and C to A substitutions in the genome.^[3] In humans, it is primarily repaired by DNA glycosylase OGG1. It can be caused by ionizing radiation, in connection with oxidative metabolism.

8-oxoG (syn) in a Hoogsteen base pair with dA (anti)

For comparison here is a standard (non-mutagenic) GC base pair with both bases in the anti configuration of the bond between base and sugar.

8-Oxoguanine^[1]

Names
IUPAC name 2-Amino-7,9-dihydro-1H-purine-6,8-dione
Other names 7,8-Dihydro-8-oxoguanine; 8-Oxo-7,8-dihydroguanine
Identifiers
CAS Number	5614-64-2 Y
3D model (JSmol)	Interactive image Interactive image
ChEBI	CHEBI:44605 Y
ChemSpider	106574 Y
ECHA InfoCard	100.024.578
MeSH	8-hydroxyguanine
PubChem CID	119315
UNII	V5WDN6HY4L Y
CompTox Dashboard (EPA)	DTXSID60231515
InChI InChI=1S/C5H3N5O2/c6-4-8-2-1(3(11)10-4)7-5(12)9-2/h(H3,6,8,9,10,11,12) Y Key: UBKVUFQGVWHZIR-UHFFFAOYSA-N Y InChI=1/C5H5N5O2/c6-4-8-2-1(3(11)10-4)7-5(12)9-2/h(H5,6,7,8,9,10,11,12) Key: CLGFIVUFZRGQRP-UHFFFAOYAZ InChI=1/C5H3N5O2/c6-4-8-2-1(3(11)10-4)7-5(12)9-2/h(H3,6,8,9,10,11,12) Key: UBKVUFQGVWHZIR-UHFFFAOYAW
SMILES O=C2NC=1N\C(=N/C(=O)C=1N2)N c12=NC(=O)N=c1[nH]c(nc2=O)N
Properties
Chemical formula	C5H5N5O2
Molar mass	167.128 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

In body fluids

Increased concentrations of 8-oxoguanine in body fluids have been found to be associated with increased risk of mutagenesis and carcinogenesis.^[4][5]

Care must be taken in the assay of 8-oxoguanine due to the ease with which it can be oxidised during extraction and the assay procedure.^[6]

Cancer, aging, infertility

The role of the deoxyriboside form of 8-oxoguanine, 8-oxo-2'-deoxyguanosine (abbreviated 8-oxo-dG or 8-OHdG) in cancer and aging also applies to 8-oxoguanine. Oxoguanine glycosylase is employed in the removal of 8-oxoguanine from DNA by the process of base excision repair. As described in oxoguanine glycosylase, deficient expression of this enzyme causes 8-oxoguanine to accumulate in DNA. This accumulation may then lead upon replication of DNA to mutations including some that contribute to carcinogenesis. 8-oxoguanine is usually formed by the interaction of reactive oxygen species (ROS) with the guanine base in DNA under conditions of oxidative stress; as noted in the article about them, such species may have a role in aging and male infertility, and 8-oxoguanine can be used to measure such stress.