The flavonoids, quercetin and isorhamnetin 3-O-acylglucosides diminish neutrophil oxidative metabolism and lipid peroxidation

Two natural flavonoids, quercetin and isorhamnetin 3-O-acylglucosides, were examined for their inhibitory influence on the in vitro production and rel ease of reactive oxygen species in polymorphonuclear neutrophils (PMNs). Th e generation of superoxide radical, hydrogen peroxide and hypochlorous acid were measured by, respectively, cytochrome c reduction, dichlorofluorescin oxidation and taurine chlorination. Membrane lipid oxidation was studied b y the thiobarbituric acid method in mouse spleen microsomes. The addition o f flavonoids at the concentration range 1-100 muM inhibited PMNs oxidative metabolism and lipid peroxidation in a dose-dependent manner. The results s uggest that these flavonoids suppress the oxidative burst of PMNs and prote ct membranes against lipid peroxidation.