M1G

M₁G (pyrimido[1,2-a]purin-10(3H)-one) is a heterocyclic compound which is a by-product of base excision repair (BER) of a specific type of DNA adduct called M₁dG. The M₁dG adduct in turn is formed by a condensation reaction between guanosine nucleotides in DNA and either malondialdehyde (propanedial) or acrolein. If not repaired, these adducts are mutagenic and carcinogenic.

Malondialdehyde is an end product of lipid peroxidation while acrolein is a result of DNA peroxidation.

M₁dG is the major endogenous DNA adduct in humans. M₁dG adducts have been detected in cell DNA in liver, leucocytes, pancreas and breast in concentrations of 1-120 per 10⁸ nucleotides. Detection and quantification of M₁dG adducts in the body as measured by free M₁G is a tool for detecting DNA damage that may lead to cancer. Free M₁G is also biomarker for oxidative stress.