RT Journal Article SR Electronic T1 Modulation of Nicotinamide Adenine Dinucleotide Phosphate Oxidase Expression and Function by 3′,4′-Dihydroxyflavonol in Phagocytic and Vascular Cells JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 261 OP 269 DO 10.1124/jpet.107.131433 VO 324 IS 1 A1 Fan Jiang A1 Nancy Guo A1 Gregory J. Dusting YR 2008 UL http://jpet.aspetjournals.org/content/324/1/261.abstract AB Previously we have demonstrated that 3′,4′-dihydroxyflavonol (DiOHF), a novel synthetic flavonol, protects against ischemia 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 reduction), NADPH oxidase activation (membrane translocation of p47phox), and subunit expression (real-time polymerase chain reaction and Western blot) were examined in differentiated 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 μM) in vascular smooth muscle cells, which appears to be attributable to its superoxide scavenging activity (EC50 = 6.1 ± 1.1 μM measured in a cell-free system). DiOHF had similar effects in HL-60 cells and isolated aortic rings. In HL-60 cells, but not endothelial or smooth muscle cells, DiOHF and quercetin (10 and 30 μM) significantly reduced the protein expression of p47phox, whereas p67phox was not altered. DiOHF did not affect phorbol ester-induced membrane translocation of either p47phox or protein kinase C in leukocytes. Our results suggest that suppression of NADPH oxidase-dependent superoxide accumulation may contribute to the cytoprotective actions of DiOHF during ischemia-reperfusion injury. The American Society for Pharmacology and Experimental Therapeutics