Natural Antioxidant Activity Evaluation Using Electrochemically Generated Superoxide Radical Anion: The SRAGE Assay.

Abstract

The antioxidant concentration and the redox potential of the oxidizing system employed in antioxidant assays are critical parameters governing the classification of antioxidant reducing power. In this study, we introduce the Superoxide Radical Anion Generated Electrochemically (SRAGE) assay, a novel electrochemical method for evaluating the antioxidant activity of natural compounds. Superoxide is the primary reactive oxygen species generated during the one-electron reduction of molecular oxygen in mitochondria, making it a biologically relevant probe for antioxidant evaluation and a distinct advantage over conventional 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) discoloration methods.In the SRAGE assay, [Formula: see text]is generated in situ by electrochemical reduction and subsequently scavenged by natural antioxidants, including rutin, ascorbic acid, quercetin, and gallic acid. The controlled generation of superoxide was achieved using cyclic voltammetry and was validated experimentally. At a concentration of 1mmol L- 1, the tested antioxidants exhibited inhibitory activities of 44.30 ± 1.31%, 52.01 ± 0.95%, 78.73 ± 2.02%, and 100.0 ± 0.12%, respectively. The ranking of antioxidant reducing power obtained from the SRAGE assay is in close agreement with that derived from the DPPH method. The proposed SRAGE assay offers a versatile electrochemical platform for evaluating the antioxidant activity of pure compounds and complex systems, including synthetic formulations, biological extracts, pharmaceutical products, and food additives.