Interaction of metronidazole with metallic ions of biological importance.

The possibility tht metronidazole exerts several of its biological actions via interaction with important metal ions was investigated. NMR spectroscopy and polarography (ac) were used to test for any interaction, to locate the probable sites for complexation, and to determine the molecular stoichiometry of any complexes formed. Of the series of divalent metal ions tests, only cupric ion showed detectable interaction with metronidazole. The predominant site of interaction of cupric ion was the unsubstituted nitrogen atom (N-3) on the metronidazole molecule. The stoichiometry of the complex was (Cu-(metronidazole)4)+2. A likely structure for the complex is presented.