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Biochem Biophys Res Commun. 2007 Aug 3;359(3):828-33. Epub 2007 Jun 6.

(-)-Epicatechin elevates nitric oxide in endothelial cells via inhibition of NADPH oxidase.

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1
Institut für Biochemie und Molekularbiologie I, Heinrich-Heine-Universität Düsseldorf, D-40001 Düsseldorf, Germany.

Abstract

Dietary (-)-epicatechin is known to improve bioactivity of (*)NO in arterial endothelium of humans, but the mode of action is unclear. We used the fluorophore 4,5-diaminofluorescein diacetate to visualize the (*)NO level in living human umbilical vein endothelial cells (HUVEC). Untreated cells showed only a weak signal, whereas pretreatment with (-)-epicatechin (10 microM) or apocynin (100 microM) elevated the (*)NO level. The effects were more pronounced when the cells were treated with angiotensin II with or without preloading of the cells with (*)NO via PAPA-NONOate. While (-)-epicatechin scavenged O2(*-), its O-methylated metabolites prevented O2(*-) generation through inhibition of endothelial NADPH oxidase activity, even more strongly than apocynin. From the effect of 3,5-dinitrocatechol, an inhibitor of catechol-O-methyltransferase (COMT), on HUVEC it is concluded that (-)-epicatechin serves as 'prodrug' for conversion to apocynin-like NADPH oxidase inhibitors. These data indicate an (*)NO-preserving effect of (-)-epicatechin via suppression of O2(*-)-mediated loss of (*)NO.

PMID:
17560937
DOI:
10.1016/j.bbrc.2007.05.200
[Indexed for MEDLINE]
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