Tocopherols oxidized alpha

Ruhho, H., Radi, R., Ansehni, D., Kirk, M., Bames, S., Butler, J., Fiserich, J. P., and Freeman, B. A., 2000, Nitric oxide reaction with hpid peroxyl radicals spares alpha-tocopherol during hpid peroxidation. Greater oxidant protection from the pair nitric oxide/alpha-tocopherol than alpha-tocopherol/ascorbate, J. Biol. Chem. 275 10812-10818. 

Andrikopoulos et al. (124) separated triglycerides, together with nine synthetic phenolic antioxidants most commonly used to prevent oxidation of edible oils and fats, as well as the natural antioxidants tocopherol and alpha-tocopherol acetate by HPLC using a reversed-phase Cl8 column and gradient elution with water/acetonitrile/methanol/isopropanol. Except for dilution of the oil with isopropanol/hexane, no further sample preparation was required. Ultraviolet detection was applied. The synthetic antioxidants PG, OG, DG, BHA, TBHQ, BHT, Ionox 100, THBP, and NDGA, as well as alpha- and delta-tocopherol and alpha-tocopherol acetate were separated. 

Botti, H., C. Batthyany, A. Trostchansky et al. 2004. Peroxynitrite-mediated alpha-tocopherol oxidation in low-density lipoprotein A mechanistic approach. Free Radir. Biol Med 36 (2) 152-62. 

On the contrary, a different antioxidant, OL-alpha-tocopherol, increases oxidation in cetomacrogol cream. This phenomenon is caused by peroxides, which originate firom dl alpha-tocopherol oxidation in the oil phase. The peroxides generate free radicals that initiate the oxidation of tretinoin. 

It is well known that excessive intake of P-carotene may lead to carotenodermia (yellow skin), and it is undoubtedly the case that some carotenoid is directly lost via the skin or through photo-oxidation in the skin. As far as is known the carotenoids are not cytotoxic or genotoxic even at concentrations up to 10 times the normal plasma concentration which may cause carotenodermia. However, they are associated with amenorrhoea in girls who may be consuming bizarre diets and, in long-term supplementation studies, with an increase in lung cancer (The Alpha-tocopherol, Beta-carotene Cancer Prevention Study Group, 1994). 

Nonaqueous Systems In nonaqueous (nonpolar) solvent systems, nitrosatlon also proceeds. In these solvents, alpha-tocopherol acts as a lipid soluble blocking agent in much the same fashion as ascorbic acid functions in the aqueous phase. Alpha-tocopherol reacts with a nitrosating agent and reduces it to nitric oxide. At the same time, alpha-tocopherol is oxidized to tocoquinone, which is the first oxidation product of vitamin E and also a normal metabolite in vivo. 

Takahashi, A., Shibasaki-Kitakawa, N., and Yonemoto, T., A rigorous kinetic model for beta-carotene oxidation in the presence of an antioxidant, alpha-tocopherol, J. Am. Oil Chem. Soc., 80, 1241, 2003. 

Nilsson, J. L. G. Daves, D. G. Folkers, K. The oxidative dimerization of alpha-, beta-, gamma-, and delta-tocopherols. Acta Chim. Scand 1968, 22, 207-218. 

Fukuzawa, K. Gebicki, J. M. Oxidation of alpha-tocopherol in micelles and liposomes by the hydroxyl, perhydroxyl, and superoxide free radicals. Arch. Biochem. Biophys. 1983, 226, 242-251. 

Omura, K. Iodine oxidation of alpha -tocopherol and its model compound in alkaline methanol unexpected isomerization of the product quinone monoketals. J. Org. Chem. 1989, 54, 1987-1990. 

McClure, TD and Liebler, DC, 1995. Electron capture negative chemical ionization mass spectrometry and tandem mass-spectrometry analysis of beta-carotene, alpha-tocopherol and their oxidation products. J Mass Spectrom 30, 1480-1488. 

Lopez-Bote C.J., Sanz Arias R., Rey A.I, Castano A., Isabel B. and Thos J. (1998). Effect of free-range feeding on omega-3 fatty acids and alpha tocopherol content and oxidative... 

Millburry P, Chen C-Y, Kwak H-K and Blumberg J. 2002. Almond skins polyphenolics act synergistically with alpha-tocopherol to increase the resistance of low-density lipoproteins to oxidation. Free Rad Res 36(1 suppl) 78—80. 

O DormeU, V. B., Chumley, P. H., Hogg, N., Bloodsworth, A., Darley-Usmar, V. M., and Freeman, B. A., 1997, Nitric oxide inhibition of Upid peroxidation kinetics of reaction with lipid peroxyl radicals and comparison with alpha-tocopherol, Biochemistry 36 15216-15223. 

MabUe, L., Fitoussi, G., Periquet, B., Schmitt, A., Salvayre, R., and Negre-Salvayre, A., 1995, alpha-Tocopherol and trolox block the early intracellular events (TBARS and calcium rises) elicited by oxidized low density lipoproteins in cultured endothelial cells. Free Radio. Biol. Med. 19 177-187. 

O Byrne, D.J., Devaraj, S., Grundy, S.M., and Jialal, I., Comparison of the antioxidant effects of Concord grape juice flavonoids alpha-tocopherol on markers of oxidative stress in healthy adults. Am. J. Clin. Nutr., 76, 1367, 2002. 

Yamauchi, K., Nagai, Y., and Ohashi, T. 1982. Quantitative relationship between alpha-tocopherol and polyunsaturated fatty acids and its connection to development of oxidative rancidity in chicken skeletal muscle. Agric. Biol. Chem. 46 2719-2724. 

There are no differences in outcome between these two patterns of hepatotoxicity, rapid risers, in whom hver failure takes only a few days to develop, and slower risers. The estimated death rate is one in 100 000, but the estimate of the FDA advisory committee was one in 15 154 at 8 months of treatment. It is unclear whether hepatotoxicity is a class effect of thiazohdinediones or whether the lipophilic alpha-tocopherol moiety of troghtazone is responsible for this effect. The basic quinone structure of alpha-tocopherol is common to other drugs that can form hepatotoxic free radicals by CYP2E1-mediated oxidation. 

Dugas, T.R., Morel, D.W., and Harrison, E.H. 1998. Impact of LDL carotenoid and alpha-tocopherol content on LDL oxidation by endothelial cells in culture. J. Lipid Res. 39, 999-1007. 

Dipyridamole has also been shown to have antioxidant effects (19). Antioxidants act to remove harmful reactive-oxygen species and protect low-density lipoproteins (LDL) from oxidation oxidized LDL plays a key role in the development and propagation of atherosclerosis. The antioxidant effects of dipyridamole may be both direct (by scavenging oxygen and hydroxyl radicals, inhibiting lipid peroxidation and oxidative modification of LDL) (20-22) and indirect (via adenosine, which reduces superoxide anion generation). Dipyridamole has been shown to be a more effective anioxidant than ascorbic acid, alpha-tocopherol, or probucol (22). 

Hodis HN, Mack WJ, LaBree L, et al. Alpha-tocopherol supplementation in healthy individuals reduces low-density lipoprotein oxidation but not atherosclerosis. The Vitamin E Atherosclerosis Prevention Study (VEAPS). Circulation 2002 106 1453-1459. 

Waters, R.E. 2nd, White, L.L., and May, J.M., Liposomes containing alpha-tocopherol and ascorbate are protected from an external oxidant stress, Free Radio. Res., 26, 373, 1997. 

Stratton, S.P. and Liebler, D.C., Determination of singlet oxygen-specific versus radical-mediated lipid peroxidation in photosensitized oxidation of lipid bilayers effect of beta-carotene and alpha-tocopherol, Biochemistry, 36, 12911, 1997. 

Yeum KJ, dos Anjos Ferreira AL, Smith D, Krinsky Nl, and Russell RM (2000) The effect of alpha-tocopherol on the oxidative cleavage of beta-carotene. Free Radicals in Biology and Medicine 29,105-14. 

Deckert, V, Desrumaux, C., Athias, A., Duverneuil, L., Palleau, V, Gambert, R, Masson, D., Lagrost, L. (2002). Prevention of LDL alpha-tocopherol consumption, cholesterol oxidation, and vascular endothelium dysfunction by polyphenolic compounds from red wine. Atherosclerosis, 165, 41-50. 

Frank, J., Budek, A., Lundh, T., Parker, R. S., Swanson, J. E., Lourenco, C. F., Gago, B., Laran-jinha, J., Vessby, B., Kamal-Eldin, A. (2006). Dietary flavonoids with a catechol structure increase alpha-tocopherol in rats and protect the vitamin from oxidation in vitro. J. Lipid Res., 47, 2718-2725. 

In fractions of butteroil containing alpha-tocopherol and copper. These workers reported that l,5-octadlen-3-one from the oxidation of long-chain polyunsaturated n-3 fatty acids was responsible for metallic notes, but the fishiness appeared to be contributed by the 2,A,7-decatrlenals or a combination of these compounds. This relationship has been explored further In our laboratory through mechanistic studies employing alpha-tocopherol and Trolox C which Is a synthetic tocopherol-type antioxidant (Figure 2). 

Since alpha-tocopherol was an essential component of the Swoboda and Peers system (52) which yielded metallic/fIshy flavors, its structural role in the directing of the flavor was of Interest. Either alpha-tocopherol (670 ppm) or Trolox C (1000 ppm) were added to steam deodorized menhaden oils (2 h at 130°C, 4 mm Hg 32) and allowed to oxidize while exposed to air and protected from the light at 65 C. As observed In previous studies (54-56), the high level of alpha-tocopherol exhibited a prooxldant effect whereas Trolox C possessed a distinct antioxidant effect in oxidizing menhaden oils (57). 

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