title: An electron spin resonance investigation of the iron-catalyzed reaction of metronidazole with cysteine.
abstract: Metronidazole is used in the treatment of protozoal and bacterial infections, and has been used as a radiation sensitizer in experimental research and clinical trials. This drug is rapidly decomposed by cysteine in the presence of ferric or ferrous iron. Electron spin resonance spectroscopy demonstrates the formation of two complexes composed of iron, cysteine, and NO. The nitric oxide is probably formed by the reduction of inorganic nitrite formed by the cleavage of the metronidazole nitro group from the imidazole ring. No such reaction occurred with the 2-nitroimidazole drug, misonidazole.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D003545:Cysteine; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005609:Free Radicals; D007501:Iron; D008795:Metronidazole
chemical_list: D005609:Free Radicals; D008795:Metronidazole; D007501:Iron; D003545:Cysteine