Electrochemical Assay to Quantify the Hydroxyl Radical Scavenging Activity of Medicinal Plant Extracts

Abstract

Abstract A new electrochemical assay has been developed which is based on quantifying the attack of OH . radicals on a self‐assembled thiol monolayer on electrodes in the presence and absence of antioxidants. The OH . radicals were produced in Fenton solutions. The radical scavengers diminish the concentration of the OH . radicals in the Fenton solution, and the extent of thiol layer destruction is monitored with the help of a redox probe in solution, the signal of which is only generated at SAM‐free electrode surface. The results of the electrochemical assay were compared with those of the standard DPPH . assay. In case of each plant extract, an excellent linear correlation was observed between the radical scavenging activity and the concentration of plant extracts; however, the scavenging properties of different plants strongly differ in the electrochemical and the DPPH . assay. Since the proposed new method probes the reactivity of radical scavengers towards OH . , one of the most important reactive oxygen radicals in tissues, it is supposed to provide much more relevant information than the DPPH . or other assays.