Electrochemical and spectroscopic studies of the interaction of (+)- epicatechin with bovine serum albumin
The mechanism of the electrochemical oxidation of (+)-epicatechin (epiCAT) in a hydro-alcoholicmedium, at a glassy carbon electrode, was studied using cyclic and square wave voltammetrictechniques and at different pHs. It proceeds in a cascade mechanism related to the two resorcinol hydroxylgroups and the other three hydroxyl groups in epiCAT which present electroactivity and is pH-dependent. Theoxidation of the 3′,4′-dihydroxyl moiety, occurs first at a very low positive potential, and it is a two-electron/two proton reversible reaction. The product obtained from the oxidation of the 3′,4′-dihydroxyl moiety thenundergoes a chemical reaction followed by an electrochemical process to give an electroinactive product. Theproposed mechanism is an ECE type mechanism. After the addition of bovine serum albumin (BSA) toepiCAT solution, the oxidation peak currents decreased with no peak potential shift and no new peaksappeared. The diffusion coefficients of both free and bound epiCAT were estimated from the cyclicvoltammetry data (Df = 2.37 9 10-10 cm2s-1 and Db = 6.28 9 10-11 cm2s-1). An epiCAT-BSA complex isformed with binding constant Kapp = 1.8 × 104, calculated from UV-vis spectroscopy data.
The oxidation process of (+)-epicatechin (I to I’ and II) in a hydro-alcoholic medium at a glassy carbon electrode follows an ECE type mechanism.
Volume 135, 2023
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