Protective Effect of Quercetin on Oxidative Stress in Glucose-6-Phosphate Dehydrogenase-Deficient Erythrocytes in Vitro

Glucose-6-phosphate dehydrogenase (G6PD) deficient subjects are vulnerable to oxidative stress. Quercetin, a flavonoids, has been employed as a potent oxygen-free radical scavenger in order to assess the protective effects of quercetin against H(2)O(2)-induced oxidative damage in G6PD-deficient and normal human erythrocytes. Erythrocytes of G6PD-deficient (n = 10) and normal (n = 10) subjects were incubated with different concentrations of quercetin. The produced thiobarbituric acid reactive substance (TBARS) and glutathione (GSH) level of erythrocytes were then subsequently measured. Different concentrations of quercetin showed no significant hemolysis, compared with the phosphate buffer solution. Upon challenge with H(2)O(2), there was a significant (p < 0.005) decrease in GSH and an increase in TBARS level in G6PD-deficient erythrocytes. With quercetin, it managed to preserve concentrations of 15 to 75 mM preserved GSH and TBARS levels of normal and G6PD-deficient erythrocytes against H(2)O(2)-induced oxidative damage. In addition to its well-established antioxidant effects, quercetin was also found to have cytoprotective properties.