RESUMO
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 [K[ao]] and standard Gibbs free energy [deltaG°]. The values of K[ao] and deltaG° ranged from 1.0 x 10[2] to 57 x 10[2] L[-1] and -18 to -27 kJmol[-1], respectively. The possible mechanism of the antioxidant reaction was regarded as E[r]C[i] mechanism i.e. reversible electron transfer followed by hydrogen atom transfer- an irreversible chemical reaction