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Amide-Based Glutathione Peroxidase Mimics: Effect of Secondary and Tertiary Amide Substituents on Antioxidant Activity

Bhabak, Krishna P and Mugesh, Govindasamy (2009) Amide-Based Glutathione Peroxidase Mimics: Effect of Secondary and Tertiary Amide Substituents on Antioxidant Activity. In: Chemistry-An Asian Journal, 4 (6). pp. 974-983.

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Official URL: http://www3.interscience.wiley.com/journal/1223291...

Abstract

A series of secondary and tertiary amide-substituted diselenides were synthesized and studied for their GPx-like antioxidant activities using H2O2 Cum-OOH, and tBuOOH as substrates and PhSH as thiol co-substrate.The effect of substitution at the free -NH group of the amide moiety in the sec-amide-based diselenides on GPx activity was analyzed by detailed experimental and theoretical methods. It is observed that substitution at the free -NH group significantly enhances the GPx-like activities of the sec-amide-based diselenides, mainly by reducing the Se center dot center dot center dot O nonbonded interactions. The reduction in strength of the Se center dot center dot center dot O interaction upon introduction of N,N-dialkyl substituents not only prevents the undesired thiol exchange reactions, but also reduces the stability of selenenyl sulfide intermediates. This leads to a facile disproportionation of the selenenyl sulfide to the corresponding diselenide, which enhances the catalytic activity. The mechanistic investigations indicate that the reactivity of diselenides having sec-or tert-amide moieties with PhSH is extremely slow; indicating that the first step of the catalytic cycle involves the reaction between the diselenides and peroxide to produce the corresponding selenenic and seleninic acids.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Willey interscience.
Keywords: Antioxidants; catalysis; redox chemistry; selenium; thiol exchange.
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Depositing User: Id for Latest eprints
Date Deposited: 09 Jul 2009 05:15
Last Modified: 09 Jul 2009 05:15
URI: http://eprints.iisc.ac.in/id/eprint/21137

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