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Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/jspui/handle/10054/3879

Title: Glutathione peroxidase-like antioxidant activity of diaryl diselenides: A mechanistic study
Authors: MUGESH, G
PANDA, A
SINGH, HB
PUNEKAR, NS
BUTCHER, RJ
Keywords: se-77 nmr-spectroscopy
structural characterization
organoselenium compound
diferrocenyl diselenides
nonbonded interaction
pz-51 ebselen
selenium
selenosubtilisin
derivatives
tellurides
Issue Date: 2001
Publisher: AMER CHEMICAL SOC
Citation: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 123(5), 839-850
Abstract: 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-ferrocernylethyl)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 Se-77 MMR 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 + H2O2 = 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.
URI: http://dx.doi.org/10.1021/ja994467p
http://dspace.library.iitb.ac.in/xmlui/handle/10054/3879
http://hdl.handle.net/10054/3879
ISSN: 0002-7863
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