Document Detail


Glutathione peroxidase-like antioxidant activity of diaryl diselenides: a mechanistic study.
MedLine Citation:
PMID:  11456617     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The synthesis, structure, and thiol peroxidase-like antioxidant activities of several diaryl diselenides having intramolecularly coordinating amino groups are described. The diselenides derived from enantiomerically pure R-(+)- and S-(-)-N,N-dimethyl(1-ferrocenylethyl)amine show excellent peroxidase activity. To investigate the mechanistic role of various organoselenium intermediates, a detailed in situ characterization of the intermediates has been carried out by (77)Se NMR spectroscopy. While most of the diselenides exert their peroxidase activity via selenol, selenenic acid, and selenenyl sulfide intermediates, the differences in the relative activities of the diselenides are due to the varying degree of intramolecular Se.N interaction. The diselenides having strong Se.N interactions are found to be inactive due to the ability of their selenenyl sulfide derivatives to enhance the reverse GPx cycle (RSeSR + H(2)O(2) = RSeOH). In these cases, the nucleophilic attack of thiol takes place preferentially at selenium rather than sulfur and this reduces the formation of selenol by terminating the forward reaction. On the other hand, the diselenides having weak Se.N interactions are found to be more active due to the fast reaction of the selenenyl sulfide derivatives with thiol to produce diphenyl disulfide and the expected selenol (RSeSR + PhSH = PhSSPh + RSeH). The unsubstituted diaryl diselenides are found to be less active due to the slow reactions of these diselenides with thiol and hydrogen peroxide and also due to the instability of the intermediates. The catalytic cycles of 18 and 19 strongly resemble the mechanism by which the natural enzyme, glutathione peroxidase, catalyzes the reduction of hydroperoxides.
Authors:
G Mugesh; A Panda; H B Singh; N S Punekar; R J Butcher
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of the American Chemical Society     Volume:  123     ISSN:  0002-7863     ISO Abbreviation:  J. Am. Chem. Soc.     Publication Date:  2001 Feb 
Date Detail:
Created Date:  2001-07-17     Completed Date:  2001-08-09     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7503056     Medline TA:  J Am Chem Soc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  839-50     Citation Subset:  IM    
Affiliation:
Department of Chemistry and the Biotechnology Centre, Indian Institute of Technology, Powai, Bombay 400 076, India.
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MeSH Terms
Descriptor/Qualifier:
Antioxidants / chemistry,  metabolism,  pharmacology*
Catalysis
Glutathione Peroxidase / metabolism*
Magnetic Resonance Spectroscopy
Models, Molecular
Peroxides / chemistry
Selenium Compounds / chemical synthesis,  chemistry,  metabolism,  pharmacology*
Spectrum Analysis
Sulfhydryl Compounds / chemistry
Chemical
Reg. No./Substance:
0/Antioxidants; 0/Peroxides; 0/Selenium Compounds; 0/Sulfhydryl Compounds; EC 1.11.1.9/Glutathione Peroxidase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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