Oxidative DNA damage induced by aminoacetone, an amino acid metabolite

We investigated DNA damage induced by aminoacetone, a metabolite of threoni ne and glycine. Pulsed-field gel electrophoresis revealed that aminoacetone caused cellular DNA cleavage. Aminoacetone increased the amount of 8-oxo-7 ,8-dihydro-2'-deoxyguanosine (8-oxodG) in human cultured cells in a dose-de pendent manner. The Formation of 8-oxodG in calf thymus DNA increased due t o aminoacetone only in the presence of Cu(II). DNA ladder formation was obs erved at higher concentrations of aminoacetone than those causing DNA cleav age. Flow cytometry showed that aminoacetone enhanced the generation of hyd rogen peroxide (H2O2) in cultured cells. Aminoacetone caused damage to P-32 -5'-end-labeled DNA fragments, obtained from the human c-Ha-ras-1 and p53 g enes, at cytosine and thymine residues in the presence of Cu(II). Catalase and bathocuproine inhibited DNA damage, suggesting that H2O2 and Cu(I) were involved. Analysis of the products generated from aminoacetone revealed th at aminoacetone underwent Cu(II)-mediated autoxidation in two different pat hways: the major pathway in which methylglyoxal and NH; are generated and t he minor pathway in which 2,5-dimethylpyrazine is formed through condensati on of two molecules of aminoacetone. These findings suggest that H2O2 gener ated by the autoxidation of aminoacetone reacts with Cu(I) to form reactive species capable of causing oxidative DNA damage. (C) 1999 Academic Press.