Interaction of flavones and their bromoacetyl derivatives with NAD(P)H:quinone acceptor oxidoreductase.
Flavones are a new type of inhibitor of NAD(P)H:quinone acceptor oxidoreductase (DT-diaphorase, EC 1.6.99.2). To further characterize the flavone binding site, three bromoacetyl derivatives of flavones, i.e., 7-bromoacetylflavone, 5-hydroxyl-7-bromoacetylflavone, and 7,8-dibromoacetylflavone, have been synthesized. These compounds have been found to be potent inhibitors that inactivate the rat quinone reductase in a time-dependent manner, suggesting that they can be used as affinity labels for the enzyme. Among the three bromoacetyl derivatives, 7,8-dibromoacetylflavone is the most potent inhibitor; however, its labeling of the quinone reductase is the least stable, so that the enzyme regains activity after a short incubation. In contrast, the inactivation of the quinone reductase by 5-hydroxyl-7-bromoacetylflavone is stable. Accordingly, this flavone derivative is the most suitable compound for labeling the flavone binding site of the enzyme. Electrospray mass spectrometry has been applied to demonstrate that 5-hydroxyl-7-bromoacetylflavone labels this enzyme in a stoichiometric manner.
Chen
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Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010.
Deng
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PS
Swiderek
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Li
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Chan
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SI
D000818:Animals; D005419:Flavonoids / Q000737:chemistry / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats
D005419:Flavonoids; D016660:NAD(P)H Dehydrogenase (Quinone)