Mechanisms underlying diquertin-mediated regulation of neutrophil function in patients with non-insulin-dependent diabetes mellitus.

We studied the effects of dihydroquercetin (3.3.4.5.7-pentahydroxyflavanone, a new Russian patented preparation) on functional activity of polymorphonuclear neutrophils from patients with non-insulin-dependent diabetes mellitus. Flavonoids (quercetin and its derivative dihydroquercetin) dose-dependently suppressed generation of anion radicals and hypochlorous acid and production of malonic dialdehyde during oxidation of neutrophil membranes. Dihydroquercetin decreased activities of protein kinase C and myeloperoxidase in activated polymorphonuclear neutrophils and could bind transition metals (Fe2+). These properties determine the ability of dihydroquercetin to decrease in vitro functional activity of polymorphonuclear neutrophils from patients with non-insulin-dependent diabetes mellitus.