55 Journal of New Materials for Electrochemical Systems Vol.25, No.1, January 2022, pp. 55-61 Journal homepage: http://iieta.org/journals/jnmes Evaluation of Antioxidant Activity by Electrochemical and Chemical Methods, Kinetics and Thermodynamic Parameters of Superoxide Anion Radical towards Cupressus sempervirens L. Extracts Zineb Rahmani 1* , Assia Belfar, Tatou Touahria 1 , Chayma Bensaci 1 , Zehour Rahmani 1,2 , Messaouda Dekmouche 1,2 , Mokhtar Saidi 1,2 and Ali Douadi 2,3 1 Laboratoire de Valorisation et Promotion des Ressources Sahariennes (LVPRS) 2 Univ Kasdi Merbah, Department of Chemistry, Faculty of Mathematics and Matter Sciences, BP 511 Route Ghardaia, Ouargla, Algeria - 30000 3 Pollution & Waste Treatment Laboratory Corresponding Author Email: zhorrahmani@gmail.com https://doi.org/10.14447/jnmes.v25i1.a08 ABSTRACT Received: December 29, 2021 Accepted: January 21, 2022 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 ( ଶ  ) made by alkaline pyrogallol, and electrochemical generation of this radical. We have studied the O2/ ଶ  redox couple on the GC in DMF. We obtained well-resolved quasi- reversible and reproducible cyclic voltammograms for the O2/ ଶ  redox couple. A ௜ ೛ ௜ ೛೎ value of 0.96 and Ep value of 160 mV for scan rates 0.1 V/s were obtained. In addition, the standard electrochemical rate constant k° is 2.31 x 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. Keywords: electrochemical behavior, pyrogallol, quasi- reversible, scavenging activity, anion superoxyde 1. INTRODUCTION Usually, molecular oxygen in the mitochondria, and through electrons, result in the production of energy, which allows our cells to stay alive. Nevertheless, this operation is not perfect: 1 to 5% of the oxygen concerned can remain free and be at the origin of the formation of reactive oxygen species (ROS) 1. Free radicals are chemical species (atoms or molecules) that have one or more single electrons (unpaired electron) on their outer shell and capable of existing independently. They can be derived from oxygen (ROS) or other atoms such as nitrogen (RNS). All are capable of reacting with membrane lipids, nucleic acids, proteins and enzymes, and other small molecules, resulting in cellular damage. Tissue destruction and degeneration can result in increased oxidant damage, by such processes as metal ion release, phagocyte activation, and disruption of mitochondrial electron transport chains (so that more electrons "escape" to oxygen to form  ଶ  ). It follows that almost any disease is likely to be accompanied by increased formation of reactive oxygen species2. Under normal physiological conditions, the concentrations of ROS are subtlety regulated by antioxidants, which can be either generated endogenously or externally supplemented3. Natural antioxidants are extracted, usually in a mixture of several compounds, from variable sources1. Among these plants a cypress that affiliate to Cupressaceae family, which is widely used in traditional medicine. Cupressaceae is a family of gymnosperm plants. It contains about 19 genera and 130 species of trees and shrubs. Cupressus sempervirens are endemic to the Mediterranean area. Popularly, it is known as "sarwel" that is considered to be a medicinal tree as its dryish leaves are used for stomach pain as well as to treat diabetes. This plant is known to anti- inflammatory and astringent4. Essential oil of Cupressus sempervirens showed antiviral activity against HSV-1 virus5. In previous article4, we reported that all extracts have high reductive activity better than butylated hydroxyanisole (BHA), whereas in α-amylase enzyme inhibitory activity, ethyl acetate fraction of fruits showed the highest α-amylase inhibitory activity. The other aim of our work was to determine the antioxidant activity especially inhibition of superoxide anion of Cupressus sempervirens extracts by chemical and electrochemical methods. 2. MATERIALS AND METHODS 2.1. Chemicals and reagents Butylated hydroxyanisole (BHA), ascorbic acid, Gallic acid and Pyrogallol were provide by Sigma-Aldrich, Sodium dihydrogen phosphate, Di-sodium-hydrogenand and N,N- Dimethylformamide (DMF HPLC-grade) were provide by Biochem chemopharma. Tetrabutyl ammonium tetrafluoroborate (TBABF4) (electrochemical grade 99 %;