Mechanism of biochemical action of substituted 4-methylbenzopyran-2-ones. Part 5: Pulse radiolysis studies on the antioxidant action of 7,8-diacetoxy-4-methylcoumarin

被引:17
作者
Raj, HG
Parmar, VS [1 ]
Jain, SC
Priyadarsini, KI
Mittal, JP
Goel, S
Das, SK
Sharma, SK
Olsen, CE
Wengel, J
机构
[1] Univ Delhi, Dept Chem, Delhi 110007, India
[2] Univ Delhi, Dept Biochem, VP Chest Inst, Delhi 110007, India
[3] Bhabha Atom Res Ctr, Div Chem, Bombay 400085, Maharashtra, India
[4] Royal Vet & Agr Univ, Dept Chem, DK-1871 Frederiksberg C, Denmark
[5] Univ Copenhagen, Dept Chem, DK-2100 Copenhagen, Denmark
关键词
D O I
10.1016/S0968-0896(99)00174-1
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
7,8-Dihydroxy-4-methylcoumarin (1, DHMC) and 7,8-diacetoxy-4-methylcoumarin (2, DAMC) were shown to possess radical scavenging property and strongly inhibit membrane lipid peroxidation. Although free polyphenolic compounds are known to be antioxidants, the antioxidant action of the acetoxy compound DAMC was intriguing. Hence, pulse radiolysis studies were undertaken to explain the antioxidant action of DAMC. Accordingly, DAMC and DHMC were separately reacted with the system generating azide radicals and the resulting transient spectra were recorded. The spectra so obtained in both the cases demonstrated peak at 410 nm, characteristic of phenoxyl radical. The rate constants for the formation of phenoxyl radical from DHMC and DAMC were 34x10(8) M-1 s(-1) and 6.2x10(8) M-1 s(-1), respectively. We propose that the free radical mediated oxidation of DAMC initially produces a radical cation that loses an acetyl carbocation to yield the phenoxyl radical. It is possible to conclude that the mechanism of the antioxidant action of DAMC follows the pathway similar to that of DHMC involving the formation of a stable phenoxyl radical. (C) 1999 Elsevier Science Ltd. All rights reserved.
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收藏
页码:2091 / 2094
页数:4
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