Electrochemical determination of glutathione in hemolysed erythrocyte by modified glassy carbon electrode

Glutathione (GSH) is a biological compound widely distributed in living cells from microbes to higher organisms. It is found mainly in its reduced form being the most abundant nonprotein sulfhydryl compound in cells [1]. The role of glutathione in the human metabolism includes protection against oxidative stress and detoxification of xenobiotics. Its viability in the reduced form may be a key factor in the health maintenance. It has been well established that a decrease in (GSH) concentration may be correlated with aging and pathogenesis of several diseases, including rheumatoid arthritis, muscular dystrophy, amyotrophic lateral sclerosis, AIDS, Alzheimer disease, and Werner syndrome [2–5]. The level of glutathione in blood may reflect glutathione status in less accessible tissues. Thus, measurement of (GSH) in blood is essential for whole-body glutathione status and can be used as an indicator of disease risks in humans [6]. In this paper, we selected electrochemical strategy to determination of glutathione by multiwall carbon nanotubes (MCNTS) -modified glassy carbon electrode. (2Z,4E) -3-(3,4- dihydroxy phenyl) -1,5-bis( 2,4- dinitrophenyl) formazon acted as a mediator between the analyte and electrode surface. The electrocatalytic oxidation of (GSH) is individually investigated at the surface of modified electrode using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Initially, cyclic voltammetry was used to investigate the redox properties of this modified electrode at various scan rates. Next, the mediated oxidation of (GSH) at the modified electrode was described. Based on differential pulse voltammetry, the oxidation of (GSH) exhibited a dynamic range between 0.05 and 100.00 μM. The influence of some (GSH) metabolites and structurally related substances of common blood components on the assay were also examined, since this electrode is to be applied in erythrocyte samples. The results showed that l-ascorbic acid produced a slight increase in the sensor response. A slight interference from cysteine was also observed, due to the structural similarity between this compound and the (GSH) molecule. Although both l-ascorbic acid and cysteine showed slight interferences, they are normally not present at a significant levels in erythrocyte samples [7]. The other interfering 75 compounds (glutamic acid, glucose, glycine,glutamic acid, …) did not show significant interferences on the sensor response. DPV was used for determination of (GSH) at the modified electrode, and quantitation of (GSH) in three different hemolysed erythrocyte samples by the standard addition method. The modified electrode showed good stability and repeatability.