Antioxidant properties of sulfur-containing biologically active substances studied by voltammetric and spectrophotometric techniques

Sulfur-containing biologically active substances (BAS) demonstrate pronounced antioxidant properties. Glutathione, cysteine, cystine, methionine, taurine, and lipoic acid occupy special positions among sulfur-containing antioxidant compounds. The antioxidant properties of these sulfur-containing BAS have been characterized and analyzed using voltammetric and spectrophotometric data. All studied BAS showed more or less pronounced antioxidant activity. Lipoic acid and glutathione exhibited the maximum antioxidant activity, which agrees with data published in the literature. Methionine showed the minimum antioxidant activity among the group of investigated BAS. The antioxidant activity was compared on the basis of the international criterion of antioxidant properties of sulfur-containing BAS, oxygen radical absorbance capacity (ORAC) with respect to a reference antioxidant (glutathione). A correlation was found between results of the voltammetric and spectrophotometric analyses.