Article ID Journal Published Year Pages File Type
10772295 Biochemical and Biophysical Research Communications 2005 4 Pages PDF
Abstract
The flavonoid (−)-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 (−)-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 1 × 10−4 and 2 × 10−4 s−1for 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 (−)-epicatechin in normal human keratinocytes and in human squamous carcinoma cells.
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Life Sciences Biochemistry, Genetics and Molecular Biology Biochemistry
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