Reactions of the nitro radical anion of metronidazole in aqueous and mixed solvent: a cyclic voltammetric study

Cyclic voltammetry was used to investigate the electrochemical reduction of metronidazole (2-methyl-5-nitro-1H-imidazole-1-ethanol) at glassy carbon and gold electrodes at different pHs in aqueous solution as well as in mixed solvent viz., aqueous dimethyl formamide. The electrogenerated nitro radical anion undergoes a disproportionation reaction, the rate constant of which is dependent on the pH, solvent composition and electrode material. The interactions of the nitro radical anion with thymine and cytosine were also investigated using a cyclic voltammetric technique. Both the bases were found to react with metronidazole nitro radical anion. The rate constants for such reactions in aqueous solutions were 3.5 × 103 and 3.0 × 103 dm3 mol−1 s−1 for thymine and cytosine, respectively.