DNA adduct formation from acrylamide via conversion to glycidamide in adult and neonatal mice

Acrylamide (AA) is a high production volume chemical with many industrial uses; however, recent findings of ppm levels in starchy foods cooked at high temperature have refocused worldwide attention on the neurotoxicity, germ cell mutagenicity, and carcinogenicity of AA. Oxidative metabolism of AA to its epoxide metabolite, glycidamide (GA), has been observed in experimental animals and humans and may be associated with many of the toxic effects of AA exposure, including formation of N7-(2-carbamoyl-2-hydroxyethyl)guanine (N7-GA-Gua) in vivo. This paper describes the characterization of two new GA-derived DNA adducts formed in vitro, N3-(2-carbamoyl-2-hydroxyethyl)adenine (N3-GA-Ade) and N1-(2-carboxy-2-hydroxyethyl)-2'-deoxyadenosine. A sensitive method for quantification of N7-GA-Gua and N3-GA-Ade, based on LC with tandem mass spectrometry and isotope dilution, was developed and validated for use in measuring DNA adduct formation in selected tissues of adult and whole body DNA of 3 day old neonatal mice treated with AA and GA. In adult mice, DNA adduct formation was observed in liver, lung, and kidney with levels of N7-GA-Gua around 2000 adducts/10(8) nucleotides and N3-GA-Ade around 20 adducts/10(8) nucleotides. Adduct levels were modestly higher in adult mice dosed with GA as opposed to AA; however, treatment of neonatal mice with GA produced 5-7-fold higher whole body DNA adduct levels than with AA, presumably reflective of lower oxidative enzyme activity in newborn mice. DNA adduct formation from AA treatment in adult mice showed a supralinear dose-response relationship, consistent with saturation of oxidative metabolism at higher doses. These results increase our understanding of the mutagenic potential of GA and provide further evidence for a genotoxic mechanism in AA carcinogenesis.