Quercetin diminishes the binding of hemoglobin to the red blood cell membrane

Hemoglobin (Hb) oxidation leads to the formation of hemichrome, which binds to the membrane and causes red blood cell removal by the reticuloendothelial system. In the present investigation, the effect of flavonoids on Hb oxidation and their binding to red blood cell (RBC) membranes were studied using tert-butyl hydroperoxide (tert-BOOH) to promote oxidative stress. The intrinsic antioxidant activity of RBC was able to prevent the binding of Hb to the membrane at tert-BOOH concentrations up to 0.4 mM. At higher concentrations, a brown pellet was observed and represented the appearance of membrane-bound oxidized Hb. Oxidations performed in membrane-free Hb solutions with an identical oxidative system showed less Hb oxidation. These observations suggest that erythrocyte membrane lipid peroxidation enhances the oxidative damage of Hb, increasing its binding to membranes. Quercetin partially protected Hb against oxidation by tert-BOOH and reduced the levels of the membrane bound hemichrome. Lipid peroxidation was also significantly suppressed by quercetin. Rutin and morin had little effect in preventing Hb binding to RBC membranes, indicating the importance of structure in the antioxidant properties of flavonoids. In the absence of oxidant, the peroxidation of erythrocyte membrane and isotonic hemolysis were protected by quercetin. These results suggest that quercetin displays a beneficial role on aging of RBC.