New Electrochemical Evaluation of the Antioxidant Capacity of Beverages with Polyoxometalates as Redox Probes

Abstract

A new method was developed to evaluate antioxidant activity based on the redox properties of polyoxometalates, which are partially reduced by antioxidants to generate a limiting potential. The polyoxometalates [PMo12O40] 3-, [PVW11O40] 4-and [SV2W10O40] 4-formed in situ were used as electrochemical probes for the new evaluation method, and their formation conditions were optimized to evaluate the antioxidant activities of gallic acid, ellagic acid, catechin, quercetin, morin, trans-ferulic acid, sesamol, α-tocopherol, δ-tocopherol and L-ascorbic acid. The observed difference between initial potential and limiting potential (ΔE) were compared with spectrophotometrically evaluated antioxidant activities. In addition, the antioxidant capacities of five beverages (Japanese green tea, concentrated catechin-containing green tea, grapefruit juice, red wine and Japanese sake) were evaluated.

Polyoxometalates in Analytical Sciences

“…Polyphenols in olive oil were determined in two linear response ranges potential shifts generated from the reaction of POMs with antioxidants. 141,142 The obtained results are consistent with those evaluated via the ORAC and DPPH methods. was reported to function as an ammonia-selective sensor (in a range of 1.0-100.0 ppm) by monitoring the resistance in a mixture of NH3, CO and H2S at room temperature.…”