Stopped-flow ESR study on the reactivity of vitamin E, vitamin C and its lipophilic derivatives towards Fremy's salt in micellar systems
✍ Scribed by Zhong-Li Liu; Zheng-Xu Han; Pin Chen; You-Cheng Liu
- Publisher
- Elsevier Science
- Year
- 1990
- Tongue
- English
- Weight
- 511 KB
- Volume
- 56
- Category
- Article
- ISSN
- 0009-3084
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✦ Synopsis
The reaction between Fremy's salt and a-tocopherol (VE), ascorbic acid (VC) and its lipophilic derivatives ascorbyl-6-caprylate (VC-8), 6-1aurate (VC-12) and 6-palmitate (VC-16) were studied by stopped-fiow ESR spectroscopy in cetyl trimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) micelles, as a model reaction of these antioxidants with alkyl peroxy radicals in biological systems. The second order rate constants for the reaction of Fremy's salt with VE in CrAB and SDS miceUes were found to be 7.9 X 103 and 2.2 M -I s -l, respectively, with as high as a 3600-fold variation. Rate constants for VC, VC-8, 35, 53 and 56 X 103 M -~ s -~ and 3.3, 2.7, 1.2 and 0.86 X 103 M -I s -~ in CTAB and SDS micelles, respectively. The results demonstrate remarkable effects of the charge type of the micelles and the side-chain of the antioxidants on the antioxidation reactivity in the micelles. It' reveals that the inter-micellar diffusion may be the rate-limiting step for antioxidation carried out in micelles.