Electrochemical Oxidation Mechanisms of the Antioxidants Daidzein and 7-Hydroxy-4-chromone

The electrochemical behavior of antioxidants daidzein (DZ) and 7‐hydroxy‐4‐chromone (7‐OH‐4‐CHM) was investigated. The oxidation of DZ is irreversible, pH‐dependent, and occurs in two steps, the first of 4′‐OH on the B‐ring and the second on the 7‐OH on the A‐ring. The oxidation of 7‐OH‐4‐CHM occurs on the 7‐OH on the A‐ring, is irreversible, pH‐dependent and proceeds in a single step. The DZ diffusion coefficient was calculated in pH 7.0 phosphate buffer to be DDZ=8.1×10−5 cm2 s−1. The detection limits of DZ and 7‐OH‐4‐CHM was calculated as LODDZ=0.08 µM and LOD7‐OH‐4‐CHM=0.13 µM.