Bhowmick, Debasish and Mugesh, Govindasamy (2012) Tertiary amine-based glutathione peroxidase mimics: some insights into the role of steric and electronic effects on antioxidant activity. In: TETRAHEDRON, 68 (51). pp. 10550-10560.
PDF
tet_68-51_10550_2012.pdf - Published Version Restricted to Registered users only Download (1MB) | Request a copy |
Abstract
In this work, several tertiary amine-based diaryl diselenides were synthesized and evaluated for their glutathione peroxidase (GPx)-like antioxidant activities using hydrogen peroxide, tert-butyl hydroperoxide and cumene hydroperoxide as substrates and thiophenol (PhSH) and glutathione (GSH) as co-substrates. A comparison of the GPx-like activity of 4-methoxy-substituted N,N-dialkylbenzylamine-based diselenides with that of the corresponding 6-methoxy-substituted compounds indicates that the activity highly depends on the position of the methoxy substituent. Although the methoxy group at 4- and 6-position alters the electronic properties of selenium, the substitution at the 6-position provides the required steric protection for some of the key intermediates in the catalytic cycle. A detailed experimental and theoretical investigation reveals that the 6-methoxy substituent prevents the undesired thiol exchange reactions at the selenium centers in the selenenyl sulfide intermediates. The 6-methoxy substituent also prevents the formation of seleninic and selenonic acids. When PhSH is used as the thiol co-substrate, the 4-methoxy-substituted diselenides exhibit GPx-like activity similar to that of the parent compounds as the 4-methoxy substituent does not block the selenium center in the selenenyl sulfide intermediates from thiol exchange reactions. In contrast, the 4-methoxy substituent significantly enhances the GPx-like activity of the diselenides when glutathione (GSH) is used as the co-substrate. (C) 2012 Elsevier Ltd. All rights reserved.
Item Type: | Journal Article |
---|---|
Publication: | TETRAHEDRON |
Publisher: | PERGAMON-ELSEVIER SCIENCE LTD |
Additional Information: | Copyright for this article belongs to PERGAMON-ELSEVIER SCIENCE LTD, OXFORD ,ENGLAND |
Keywords: | Antioxidant activity;GPx mimics;Selenoenzymes;Selenium;Thiol exchange |
Department/Centre: | Division of Chemical Sciences > Inorganic & Physical Chemistry |
Date Deposited: | 31 Jan 2013 12:47 |
Last Modified: | 31 Jan 2013 12:47 |
URI: | http://eprints.iisc.ac.in/id/eprint/45693 |
Actions (login required)
View Item |