- 'Vitamin CE,' a novel prodrug form of vitamin E
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Reaction of 5a-bromo-α-tocopherol with ascorbic acid produces 5a- tocopheryl ascorbate which is designated 'vitamin CE.' This novel tocopherol derivative represents an interesting prodrug form of α-tocopherol (vitamin E) that is stable under acidic conditions, but regenerates finely dispersed vitamin E in basic media. The reaction mechanism of the base-induced decomposition of vitamin CE involves elimination of ascorbate and production of an ortho-quinone methide intermediate that oxidizes ascorbate, and is reduced to vitamin E. Kinetic experiments showed the reaction to proceed in the pH range of 8 to 11 under physiological conditions. Tissue culture measurements demonstrated that vitamin E generated from the novel derivative is absorbed at much higher rates than conventional preparations and can even be absorbed under simulated conditions of malabsorption where there is no uptake of conventional vitamin E medications.
- Rosenau, Thomas,Habicher, Wolf Dieter
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- Identification of α-tocopherol oxidation products in triolein at elevated temperatures
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The effect of high-temperature treatment on the stability of α-tocopherol (1) in triolein was assessed under a reduced-pressure atmosphere (4-40 mbar) simulating the deodorization step of the refining of vegetable oils. A marked degradation of i was observed, which increased with increasing temperature (180-260°C) and heating time (20-80 min). The degradation of I in triolein at 240°C was inhibited by the addition of the synthetic antioxidant TBHQ or when heating was performed under nitrogen atmosphere, indicating oxidative degradation. The oxidation products were isolated and identified as α-tocopherolquinone (2), 4a,5-epoxy-α-tocopherolquinone (3), and 7,8-epoxy-α-tocopherolquinone (4).
- Verleyen, Tom,Verhe, Roland,Huyghebaert, Andre,Dewettinck, Koen,De Greyt, Wim
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- Synthesis and analytical characterization of all N–N-coupled, dimeric oxidation products of α-tocopheramine: hydrazo-, azo-, and azoxy-tocopherol
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Tocopherols are a mixture of antioxidants which are commonly referred to as vitamin E. Tocopheramines differ from tocopherols by an amino function in lieu of the phenolic OH group. They are potent antioxidants which are used in biomedical scenarios as well as stabilizers for polymers against aging. While in aqueous media α-tocopheramine is mainly oxidized to α-tocopherylquinone and N-oxidized by-products, oxidation in apolar media or in polymeric matrices mainly leads to dimeric compounds of hitherto unknown structure. In the present study, we synthesized the whole array of N,N-dimerization product of α-tocopheramine, including the hydrazo, azo, and azoxy derivatives for the first time, and provided comprehensive analytical data as well as general protocols to access the compounds in straightforward syntheses. These results can now be used to identify the common oxidation by-products of α -tocopheramine in different reaction systems. Graphic abstract: [Figure not available: see fulltext.]
- Patel, Anjan,Rosenau, Thomas
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- Identification of α-Tocopherol and Its Oxidation Products by Ultra-Performance Liquid Chromatography Coupled with Quadrupole Time-of-Flight Mass Spectrometry
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This study aimed to determine α-tocopherol (α-T) and its thermal oxidation products simultaneously. A novel method based on an ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) was developed. This approach was achieved by means of a BEH C18 analytical column under gradient elution conditions with eluents of acetonitrile/isopropanol (1:9, v/v) and acetonitrile/water (4:6, v/v). Compounds were elucidated through exact molecular mass and fragmentation ions obtained from the Q-TOF-MS detector. Two oxidation products, α-tocopheryl quinone and 5-formyl-?3-tocopherol, were identified, and one new compound was determined. This approach offered a simple, precise, and reliable method to determine oxidation products of α-T, which may give a way to understand the mechanism of the thermal oxidative process of α-T.
- Tang, Chuanhui,Tao, Guanjun,Wang, Yue,Liu, Yuanfa,Li, Jinwei
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p. 669 - 677
(2020/01/31)
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- Copper(II)-catalyzed oxidation of d-α-tocopherol by oxygen in aqueous solution
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α-Tocopherol (α-Toc) was solubilized in aqueous solutions using 13 solubilizing agents and the products of oxidation by oxygen in the presence and the absence of Cu(II) were analyzed by HPLC. In the presence of Cu(II), the oxidation was accelerated and 5-
- Nagata, Yoshiko,Miyamoto, Chie,Matsushima, Yoshikazu,Matsumoto, Shigenobu
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