Characterization of the mutagen 2-amino-3-methylimidazo[4,5-f]quinoline prepared from a 2-methylpyridine/creatinine/acetylformaldehyde model system

A mixture of 2-methylpyridine, creatinine and aldehydes was heated in diethylene glycol containing 5% water for 1 h at 140°C. The mutagenic compounds were purified by XAD-2 column chromatography, acid/base partition, blue cotton treatment, thin layer chromatography and HPLC. The active substances purified from each step were monitored by their mutagenicity with Salmonella typhimurium TA98 in the presence of S9 mix. Among the mutagens collected, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) was isolated from HPLC, and was identified by its UV and mass spectrum using a photodiode array detector and mass spectrometry. Our findings appear to be the first experimental evidence to substantiate the hypothetical pathway for the formation of IQ mutagens from a heated model system consisting of a pyridine or pyrazine derivative, an aldehyde and creatinine or creatine.