Characterization of semiquinone free radicals formed from stilbene catechol estrogens. An ESR spin stabilization and spin trapping study. J Biol Chem 1989 Jul 05;264(19):11014-9
Date
07/05/1989Pubmed ID
2544580Scopus ID
2-s2.0-0024406075 (requires institutional sign-in at Scopus site) 31 CitationsAbstract
Electron spin resonance spectroscopy has been used to detect, characterize, and to infer structures of o-semiquinones derived from stilbene catechol estrogens. Radicals were generated enzymatically using tyrosinase and were detected as their Mg2+ complexes. It is suggested that initial hydroxylation of stilbene estrogen gives a catechol estrogen in situ; subsequent two-electron oxidation of the catechol to the quinone, followed by reverse disproportionation, leads to the formation of radicals. Consistent with this mechanism, o-phenylenediamine, a quinone trapping agent, inhibits formation of o-semiquinones. A competing mechanism of radical production involves autoxidation of the catechol. Hydroxyl radicals are shown to be produced in this system via a mechanism involving reduction of iron and copper complexes by stilbene catechols. Possible differences in the reactivity of stilbene ortho- and para-semiquinones are discussed.
Author List
Kalyanaraman B, Sealy RC, Liehr JGAuthor
Balaraman Kalyanaraman PhD Professor in the Biophysics department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
BenzoquinonesCyclic N-Oxides
Dienestrol
Diethylstilbestrol
Electron Spin Resonance Spectroscopy
Estrogens, Catechol
Free Radicals
Hexestrol
Magnesium
Molecular Structure
Monophenol Monooxygenase
Oxidation-Reduction
Quinones
Spin Labels
Stilbenes
