Modulation of Nicotinamide Adenine Dinucleotide Phosphate Oxidase Expression and Function by 3,4-Dihydroxyflavonol

Previously we have demonstrated that 3,4-dihydroxyflavonol (DiOHF), a novel synthetic flavonol, protects against isch-emia reperfusion injury in both heart and brain. In this study, we characterized the pharmacological effects of DiOHF on phagocytic and vascular NADPH oxidase. Superoxide release (lucigenin-enhanced chemiluminescence or cytochrome c re-duction), NADPH oxidase activation (membrane translocation of p47phox), and subunit expression (real-time polymerase chain reaction and Western blot) were examined in differenti-ated HL-60 cells, human neutrophils, vascular endothelial and smooth muscle cells, and mouse aorta. DiOHF concentration dependently suppressed superoxide accumulation (EC50 8.4 1.7 M) in vascular smooth muscle cells, which appears to be attributable to its superoxide scavenging activity (EC5