THERMODYNAMIC PARAMETERS OF THE RIBOFLAVIN REDOX REACTIONS IN AQUEOUS-SOLUTIONS

The redox properties of the riboflavin system were investigated between 10 and 35 °C by thin layer voltammetry on gold electrodes. The values of standard potentials, temperature coefficients, ionization constants and thermodynamic parameters (ΔGo298, ΔHo298 and ΔSo298) for all oxidation-reduction and acid-base equilibria between the conjugated forms of riboflavin were determined. It was found that temperature significantly influences the redox properties of riboflavin, particularly in the physiological region of pH where the reduction proceeds in two steps with the formation of stable semiquinone. © 1979.