Mass spectrometry of 2-substituted 5-nitro-2-furyl thiazoles. Identification of microsomal nitroreduction products by electron impact mass spectrometry.

The electron impact mass spectral fragmentation of nitro heterocyclic carcinogens N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide, 2-amino-4-(5-nitro-2-furyl)thiazole, 2-methyl-4-(5-nitro-2-furyl)thiazole and 2-methylamino-4-(5-nitro-2-furyl)thiazole were studied. The molecular ions undergo two modes of cleavage: one giving [M-84]+ ions which include the 2-substituted thiazole ring, while the other gives rise to the fragment [M-74]+ ions. The products of anaerobic microsomal nitroreduction of 2-methyl-4-(5-nitro-2-furyl)thiazole were isolated and purified by high-pressure liquid chromatography. The metabolites undergo different fragmentation patterns compared to the parent nitro analogs. Metabolites from anaerobic enzymatic reduction showed identical gas chromatographic, high-pressure liquid chromatographic and thin-layer chromatographic properties to the chemically synthesized material. The metabolites were identified as 1-(2-methyl-4-thiazolyl)-3-cyano-1-propenone and 1-(2-methyl-4-thiazolyl)-3-cyano-1-propane by mass spectral fragmentation pattern.