Eletrodo de Carbono Vítreo Modificado com Guanina ou Adenina e Nitrofural – Interação entre espécies reativas in situ

GCE was modified with nitrofural (NFZ) and the nitrogenous bases of DNA, guanine (GUA) or adenine (ADN) to evaluate, in aqueous medium, the interaction between the reactive intermediate of the NFZ reduction process(1) and the nitrogenous bases. The differential pulse voltammograms presented in Figure 1 illustrate the re-oxidation process of the NFZ reduced derivatives (blue lines), as well as, their products of interaction with ADN (A) and GUA (B), (red lines). Lower current values for the oxidation of the NFZ reduced derivatives were observed in presence of ADN. In contrast, higher values of current were obtained in the presence of GUA. The main hypothesis is that the nitrogenous bases form an adduct with the nitro radical anion, which mainly differ in stability. While the RNO2 ●‾/ADN adduct consumes the reactive intermediate of the nitro compound, the RNO2 ●‾/GUA adduct can be involved in a disproportionation mechanism(2), generating RNO2 and RNO. Therefore, RNO can be re-oxidized to RNO2●‾ at Epa0; RNO2 ●‾ to RNO2 at Epa1 and its adduct to RNO2 at Epa2. Epa3 corresponds to the oxidation of the azomethine group.