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

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.