Kinetic study of DPPH scavenging in the presence of mixture of Zinc and Vitamin C as an antioxidant

Abstract

Reactions of free radicals and reactive oxygen species (ROS) with biological molecules in vivo play
an important physiological role in many diseases. 2,2-diphenyl-1-picrylhydrazyl (DPPH) is a stable free radical
and often used as a routine reagent to evaluate the antioxidant capacity of an antioxidant. This study was
undertaken to investigate the free radical-scavenging and antioxidant activities of Zinc, Vitamin C and mixture
of them. UV-Vis spectrophotometry method was used to evaluate the ability of Zinc, Vitamin C and mixture of
them to scavenge DPPH radical. The kinetic parameters such as rate constant and activation energy in
experimental conditions were calculated. The rate constants of the H atom abstraction by DPPH ( 1 k ), in the
presence of Zinc, Vitamin C and mixture of them were obtained (0.4209, 2.092 and 1.82 min-1) respectively,
under pseudo-first-order conditions at 25 oC.