How do phenolic compounds react toward superoxide ion? A simple electrochemical method for evaluating antioxidant capacity.
The reactivities of different phenols and polyphenols versus superoxide ion (O₂(•-)) were investigated as an easy-to-handle electrochemical method for evaluating antioxidant capacities. In view of this application, the O₂/O₂(•-) couple and associated reactions between O₂(•-) and polyphenols (or phenols) were examined in an aprotic solvent [dimethylformamide (DMF)] by cyclic voltammetry. Comparisons based on simple criteria (reversibility of the O₂ reduction in the presence of the phenolic compound, electron stoichiometry, or apparent kinetic constants) allow discriminations between the possible mechanistic pathways (acid-base or radical reaction type). The results highlight that the proton-transfer and radical-transfer pathways are both present for monophenols and polyphenols, with the relative contributions of the two pathways depending on the phenol structure. In agreement with the literature, polyphenols containing an o-diphenol ring (as in flavonoids) were found to present the highest reactivities.
René
Alice
A
MaCSE Group, Sciences Chimiques de Rennes, CNRS, UMR No. 6226, ENSCR, Université de Rennes 1, Avenue du Général Leclerc, 35042 Rennes Cedex, France.
Abasq
Marie-Laurence
ML
Hauchard
Didier
D
Hapiot
Philippe
P
D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods*; D007477:Ions / Q000737:chemistry; D007700:Kinetics; D015394:Molecular Structure; D010636:Phenols / Q000737:chemistry*; D013481:Superoxides / Q000032:analysis* / Q000737:chemistry; D013816:Thermodynamics
D000975:Antioxidants; D007477:Ions; D010636:Phenols; D013481:Superoxides