Fluorometric detection of 2-amino-3-methylimidazo[4,5-f]quinoline, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline and their N-acetylated metabolites excreted by the rat

A sensitive fluorometric method has been developed for the determinationof carcinogenic amino imidazoazaarenes (AIA compounds) whichare formed during the cooking of food. They are separated byt.l.c. followed by spraying with dimethylsulfoxide and visualizationby long-wave u.v. light. Quantification is done by fluorescencescanning. This method was applied to the determination of themetabolites in urine and feces from rats given 5 mg/kg bodywt i.p. of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ). Metabolitesextractable by organic solvents were identified as the parentcompound and their N-acetylated derivatives (AcIQ, AcMeIQ).Between 0.1 and 1% of the administered dose was recovered asthese metabolites in urine during 24 h. The amounts of MeIQand AcMeIQ found in feces were 1 and 3% respectively. AcIQ wasnot detected in feces while IQ, MeIQ and their N-acetylatedderivatives were found in bile. The metabolites in urine wereidentified by m.s. and in feces by t.l.c. and their fluorescentproperties. When IQ or MeIQ were incubated with rat liver cytosolin the presence of acetyl-CoA, N-acetylated derivatives wereformed. The reverse reaction, deacetylation, also took placein the liver cytosol, with K_m values of 67 and 32 µM forAcIQ and AcMeIQ respectively.