Evaluation of Antioxidant Activity by Electrochemical and Chemical Methods, Kinetics and Thermodynamic Parameters of Superoxide Anion Radical towards Cupressus sempervirens L. Extracts

Abstract

For the first time in this report, we determined the antioxidative capacity of Cupressus sempervirens extracts by using two methods such as inhibition of superoxide anion (0∙−2) made by alkaline pyrogallol, and electrochemical generation of this radical. We have studied the O2/0∙−2 redox couple on the GC in DMF. We obtained well-resolved quasireversible and reproducible cyclic voltammograms for the O2/O∙−2 redox couple. A ipaipc value of 0.96 and ΔEp value of 160 mV for scan rates 0.1 V/s were obtained. In addition, the standard electrochemical rate constant k∘ is 2.31×10−3 cm s−1; all these characteristics clearly show that the system is quasi-reversible. Furthermore, we have used the cyclic voltammetric to study the antioxidant capacity of Cupressus sempervirens extracts. The thermodynamic feasibility of the radical scavenging by extracts was accounted in term of standard free energy ΔG∘, which ranged from -8.934 to 0.042 kJ/mol.

Electrochemical Characterization of the Antioxidant Properties of Medicinal Plants and Products: A Review

“…•-) with antioxidants of various types (phenolics, ascorbic acid, tocopherols) [97][98][99][100][101][102][103]. Oxygen dissolved in the supporting electrolyte undergoes reversible one-electron electroreduction on the electrode with the formation of superoxide anion radical (Scheme 1 reaction (1)), which interacts with antioxidants (Scheme 1 reaction (2)).…”

“…The reduction currents of oxygen are increased after the reaction with the antioxi dants, whereas oxidation currents are decreased which is caused by reactions ( 2) and (3) Cyclic voltammetry (CV) is used for the reactions monitoring and typical curves are pre sented in Figure 6 [98]. Electrolysis is performed in the presence of a supporting electrolyte (tertiary ammo nium salts) in dimethylformamide (DMF) [97][98][99]103], dimethylsulfoxide (DMSO) [100] or acetonitrile [101], which are rich in dissolved oxygen (up to mM level) using a glassy carbon (GCE) [97][98][99][100][101], or platinum [102] and multi-walled carbon nanotubes modified (MWCNTs/GCE) electrodes [103].…”