Antioxidant and Pro-oxidant Effect of the Thiolic Compounds N -acetyl- l -cysteine and Glutathione against Free Radical-induced Lipid Peroxidation

Abstract

The antioxidant ability of thiol compounds has been the subject of much of the current research about oxidative stress. The direct scavenging of hydroxyl radicals by thiols has been suggested as their protection mechanisms. Nevertheless, the interaction of thiols with reactive radicals can generate thiyl radicals, which, in turn, may impart a pro-oxidant function. The purpose of this study has been to establish the effect of the thiol compounds N-acetyl-L-cysteine (NAC) and glutathione (GSH) against the peroxidative processes involving membrane lipids. The results obtained support the ability of NAC and GSH to suppress the 2,2 0 -azobis-(2-amidinopropane) dihydrochloride (AAPH)-dependent or to enhance the Fe 2+ /H 2 O 2 -dependent oxidative actions. The evaluation of thiobarbituric acid reactive substances (TBARS) production, the study of the influence of oxidants on membrane fluidity and the measurements of the changes in the fluorescence of bilayer probes, such as 3-( p-(6-phenyl)-1,3,5-hexatrienyl)phenylpropionic acid (DPH-PA), have shown the antioxidant and pro-oxidant effects of both NAC and GSH. Also their dependence on the nature of the radicals generated by the oxidative systems used has been shown. The use of ESR spectroscopy has allowed us to establish the ability of these compounds to scavenge the AAPH-derived radicals, to determine the formation of thiyl radicals in the iron-mediated oxidation and to evaluate the enhanced production of hydroxyl radicals by NAC and GSH.

Metabolic endophenotype and related genotypes are associated with oxidative stress in children with autism

“…The essential intracellular reducing environment is maintained by the high ratio of reduced glutathione (GSH) to the oxidized disulfide (GSSG) form of glutathione (Schafer and Buettner 2001). The GSH/GSSG redox equilibrium regulates a pleiotropic range of functions that include nitrogen and oxygen free radical scavenger (Dickinson et al 2003), protein redox status and enzyme activity (Klatt and Lamas 2000), cell membrane integrity and signal transduction (Sagristá et al 2002;Dickinson and Forman 2002), transcription factor binding and gene expression (Deplancke and Gaskins 2002), phase II detoxification (Pastore et al 2003), and apoptosis (Hall 1999). Under normal physiologic conditions, glutathione reductase enzyme activity is sufficient to maintain the high GSH/GSSG redox ratio.…”

Pro-Oxidative Processes and Cytokine Response to Training in Professional Basketball Players

“…In basketball players, TBARS level directly correlated with PC in both training periods, indicating an integration of the peroxidation with the carbonylation process. It has been known that lipid radicals induce protein damage, and oppositely, thiyl radicals can cause the peroxidation of lipids, such as arachidonic acid (Sagrista et al, 2002).…”

Role of germanium L-cysteine α-tocopherol complex as stimulator of some antioxidant defense systems in gamma-irradiated rats

“…There is need for non-toxic and inexpensive drugs for clinical radiation protection. Antioxidant agents may help protect against chemically induced or radiation induced toxicity in rats (5). Previous studies have indicated that some commonly used antioxidants of plant origin include vitamin E, vitamin C, selenium, phenolic compounds, carotenoids and flavonoids (6).…”