Radiolabelling studies of free radical reactions using muonium (the second hydrogen radioisotope): evidence of a direct antioxidant role for vitamin k in repair of oxidative damage to lipids
✍ Scribed by Christopher J. Rhodes; Timothy C. Dintinger; Humphrey A. Moynihan; Ivan D. Reid
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 73 KB
- Volume
- 38
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Following the recent suggestion that oxidative damage to lipids might involve the formation of C-2 glyceryl radicals, in addition to main-chain allylic radicals, which are generally thought important, we studied the kinetics of potential 'repair' reactions by vitamin E and vitamin K 1 (which are lipophilic and tend to locate in cell membranes) with 1,1,2-trimethylallyl and 1-acetoxyprop-2-yl radicals as models of, respectively, main-chain and glyceryl-type radicals. The second-order rate constants for the reaction between trimethylallyl radicals and vitamin E and vitamin K 1 are 9.38 ð 10 6 and 3.54 ð 10 8 l mol 1 s 1 and those between 1-acetoxyprop-2-yl radicals and vitamin E and vitamin K 1 are 1.76 ð 10 8 and 2.03 ð 10 6 l mol 1 s 1 , respectively. The results suggest that direct scavenging of glyceryl radicals by vitamin E should be an efficient process, and of main-chain allylic radicals fairly so. Additionally, it appears that vitamin K 1 can act directly as a 'radical repair agent,' given its relatively high reactivity with allylic radicals (four times faster than with vitamin E), so prior reduction to the quinol form may be unnecessary. Copyright