Voltammetric determination of antioxidant character in Berberis lycium Royel, Zanthoxylum armatum and Morus nigra Linn plants

The antioxidant activity potential of three different plant extracts was investigated against superoxide anion radical while employing cyclic voltammetry technique. The plants Berberis lyceum Royle, Morus nigra Linn and Zanthoxylum armatum were selected because of their potential use in the traditional medicine. The voltammetric response of the electrochemically generated superoxide anion radial in DMSO was monitored in the absence and presence of the plat extracts. The decrease in the current was interpreted in terms of antiradical activity of the added extract. The thermodynamic feasibility of the radical scavenging by extracts was accounted in terms of antioxidant activity coefficient (Kao) and standard Gibbs free energy (ΔG°). The values of Kao and ΔG° ranged from 1.0 x 102 to 57 x 102 L-1 and -18 to -27 kJmol-1, respectively. The possible mechanism of the antioxidant reaction was regarded as ErCi mechanism i.e. reversible electron transfer followed by hydrogen atom transfer- an irreversible chemical reaction.