Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10772295 | Biochemical and Biophysical Research Communications | 2005 | 4 Pages |
Abstract
The flavonoid (â)-epicatechin was previously demonstrated to interfere with tyrosine nitration by peroxynitrite [Biochem. Biophys. Res. Commun. 285 (2001) 782]. This effect was hypothesized to be based upon an interaction of epicatechin with a transiently generated tyrosyl radical. In the present study, using electron paramagnetic resonance, we demonstrate that (â)-epicatechin is capable of destabilizing the tyrosyl radical of the mouse ribonucleotide reductase R2 component. First-order rate constants for the disappearance of tyrosyl radical signals were 1Â ÃÂ 10â4 and 2Â ÃÂ 10â4Â sâ1for epicatechin and hydroxyurea, a well-known tyrosyl radical scavenger, respectively. In keeping with scavenging the ribonucleotide reductase tyrosyl radical, cellular production of deoxyribonucleotides and DNA synthesis were impaired by (â)-epicatechin in normal human keratinocytes and in human squamous carcinoma cells.
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Authors
Peter Schroeder, Nina Voevodskaya, Lars-Oliver Klotz, Peter Brenneisen, Astrid Gräslund, Helmut Sies,