Incorporation of carbon atoms from glucose into the food mutagens MeIQx and 4,8-DiMeIQx using 14C-labelled glucose in a model system

Mixtures of creatinine, glucose and threonine with the additionof a small amount, 250 µCi, of U-¹⁴C]glucose, 1-¹⁴C]glucoseor 6-¹⁴C]glucose were heated at 180°C for 30 min in anaqueous model system. The mixtures were purified and analysedusing HPLC, scintillation and Ames tests. 2-Amino-3,8-dimethylimidazo4,5-f]quinoxaline(MeIQx) and 2-amino-3,4,8-trimethylimidazo4,5-f]quinoxaline(4,8-DiMeIQx) were detected as the main radioactive mutagens.The amount of MeIQx and 4,8-DiMeIQx produced from threoninewas estimated at 18 and 60 nmol/mmol glucose respectively. Radioactivecarbon atoms originating from glucose were also shown to beincorporated into 2-amino-3-methylimidazo4,5-f]quinoxaline(IQx). The specific activity was calculated to be 0.6, 0.3 and0.1–0.3 mCi/mmol for MeIQx, 4,8-DiMeIQx and IQx respectivelyfor all three labelled forms of glucose. By the incorporationof carbon atoms originating from glucose into the imidazoquinoxalinemutagens it was clearly demonstrated that glucose is a precursorin the formation of these food mutagens.