Chromanoxyl radical

FIGURE 6.3 Resonance forms and general reactions of chromanoxyl radical 2. 

Matsuo, M. Matsumoto, S. Electron spin resonance spectra of the chromanoxyl radicals derived from tocopherols (vitaminE) and theirrelated compounds. Lipids 1983,18, 81-86. 

Mukai, K. Tsuzuki, N. Ouchi, S. Fukuzawa, K. Electron spin resonance studies of chromanoxyl radicals derived from tocopherols. Chem. Phys. Lipids 1982, 30, 337-345. 

Tsuchija, J. Niki, E. Kamiya, Y. Oxidation of lipids IV. Formation and reaction of chromanoxyl radicals as studied by electron spin resonance. Bull. Chem. Soc. Jpn. 1983, 56, 229-232. 

Niki, E., Tsuchiya, J., Tanimura, R. and Kamiya, V., "Regeneration of Vitamin E From a-Chromanoxyl Radical by Glutathione and Vitamin C", Chem. Letters, 1982, 6, 789. 

The differing H donating potencies of various forms of vitamin E depend, in part, on how w ell the lone pair electrons car stabilize the vitamin E radical. The vitamin E radical may also be called a chromanoxyl radical. 

Kagan VE, Shevedova A, Serbinova E, Khan S, Swanson C, Powell R and Packer L (1992) Dihydrolipoic acid — a universal antioxidant both in the membrane and in the aqueous phase. Reduction ofperoxyl, ascorbyl and chromanoxyl radicals. Biochem Pharmacol 44 1637—1649. 

The chromanoxyl radical is fairly stable, due to de-localization of the unpaired electron. The oxygen in the heterocyclic chroman ring is fixed in such a position that there is considerable overlap between the 2p-type orbital of the lone electron pair of the oxygen and the aromatic it-system (Burton and Ingold 1981, Burton et al. 1985). This permits stabi-... 

The chromanoxyl radical is fairly stable, due to de-localization of the unpaired electron. The oxygen in... 

In the reaction with peroxyl radicals, the higher rate of tocopherols compared with DBHA (cf. Table 3.39) is based on the fact that the chromanoxyl radical formed on H-abstraction is more stable than the phenoxyl radical. Both types of radical are stabilized by the following resonance ... 

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