Antioxidant Properties of Adrenaline in the Presence of Ge-132

Using cyclic voltammetry, UV and 1H NMR spectroscopy, we have investigated the effect of 2-carboxyethylgermanium (Ge-132), the most common germanium-containing dietary supplement, on the antioxidant activity of adrenaline in aqueous solutions. The complex formed by adrenaline and Ge-132 is oxidizable at 400 mV more positive potentials compared to non-coordinated adrenaline which corresponds to its 9 kcal/mol more difficult oxidation. An equilibrium constant of the complex formation was estimated (1300 m–1). It was shown that at the concentrations <10–3 m the complex Ge-132-adrenaline is mostly dissociated to the initial compounds, and the influence of Ge-132 on the antioxidant properties of adrenaline becomes significant only when the former is in excess. Considering that such concentrations are typical for physiological conditions, this fact can be significant in identifying the mechanism of the biological action of Ge-132 and its interference with the biological catechols. © 2019