The effect of metal ions on the electrochemistry of the furazolidone

A study of the complexing properties of the furazolidone (Fu) with cadmium, copper, nickel, zinc and cobalt was performed in dimethylformamide (DMF) using cyclic voltammetry (CV) and differential pulse (DP) methods with glassy carbon (GC) and dropping mercury electrode (DME). The applied methods allow one to distinguish between the free drugs, free metal ions and their complexes as well as provide evidence that different forms of complexation exist. In aprotic DMF medium, the four electrons reductive peak of the nitro group (NO2) to hydroxylamine (RNHOH) was changed to a one electron reversible peak corresponding to RNO2- and to a subsequent more negative three electrons irreversible peak due to RNHOH.The one electron reduction of Fu to the nitro radical anion RNO2- is slightly shifted to positive potentials upon addition of Cd(II), Ni(II), Zn(II), Cu(II) and Co(II) and is consistent with the formation of complexes involving the nitro group and the oxygen of the adjacent furan of Fu. The redox potential of the hydroxylamine in Fu was also shifted to a more positive potential in the presence of metal ions, but their currents decreased. The complexation at different mole ratios was also investigated. The results suggest that in vivo, metal ions, such as Cd(II), Ni(II), Zn(II), Cu(II) and Co(II) facilitate the initial reduction of Fu by capturing the RNO2- after Fu is reduced by biological reductants.