Electrochemically mediated oxidation of glutathione and N-acetylcysteine with 4,4′-biphenol

The electrochemical oxidation of 4,4′-biphenol was studied at a glassy carbon electrode in the presence of glutathione and N-acetylcysteine, using cyclic voltammetry as a diagnostic technique. The results indicate a complicated catalytic system. The catalytic current depends on the concentration of glutathione (or N  -acetylcysteine) and solution's pH. In this work a unique kinetic zone diagram for catalytic behavior of 4,4′-biphenol in the presence of glutathione is constructed using the variables “excess factor” (γ=CGSH0/CB0) and “kinetic parameter” (λ=pH/v)(λ=pH/v). This paper also describes the elucidation of second order homogeneous catalytic reaction (EC′) of 4,4′-biphenol with glutathione and N-acetylcysteine. In addition, the observed homogeneous rate constant of catalytic reaction of electrochemically generated 4,4′-diphenoquinone with glutathione (or N-acetylcysteine) was investigated using digital simulation method.

Graphical abstractA unique kinetic zone diagram for catalytic behavior of 4,4′-biphenol in the presence of glutathione is constructed using the variables “excess factor” (γ=CGSH0/CB0) and “kinetic parameter” (λ=pH/v)(λ=pH/v).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Electrochemical oxidation of 4,4′-biphenol. ► Catalytic oxidation of glutathione and N-acetylcysteine using 4,4′-biphenol as a redox mediator. ► A kinetic zone diagram for catalytic behavior of 4,4′-biphenol. ► The observed homogeneous rate constant of catalytic reaction of electrochemically generated 4,4′-diphenoquinone.