Identification of 4-Oxo-2-hexenal and Other Direct Mutagens Formed in Model Lipid Peroxidation Reactions as dGuo Adducts

We searched for mutagens that react with 2‘-deoxyguanosine (dGuo) in model systems of lipid peroxidation. To autoxidation systems of methyl linoleate (model of ω-6 fat), methyl α-linolenate (MLN) (model of ω-3 fat), and commercial salad oil, dGuo was added. The reaction mixtures were analyzed by HPLC. Six adducts were detected, and their structures were determined by ¹H and ¹³C NMR, UV, and mass spectra and by comparison with synthetic authentic samples. The mutagens that reacted with dGuo to form these adducts were proposed as glyoxal, glyoxylic acid, ethylglyoxal, and 4-oxo-2-hexenal (4-OHE). The formation of 8-hydroxy-dGuo, an oxidized product of dGuo, was also detected in the model reaction mixtures. Among them, glyoxal and glyoxylic acid are known mutagens, while ethylglyoxal and 4-OHE, produced from MLN, have not been reported as mutagens thus far. We confirmed the mutagenic activity of 4-OHE with Salmonella strains, TA100 and TA104, without S9 mix. These compounds may be involved in lipid peroxide-related cancers.