16698-35-4Relevant academic research and scientific papers
Kinetics of the reaction by which natural vitamin E is regenerated by vitamin C
Nagaoka, Shin-ichi,Kakiuchi, Takuhiro,Ohara, Keishi,Mukai, Kazuo
, p. 26 - 32 (2007)
The rate constant and activation energy of the regeneration reaction of natural vitamin E by vitamin C were determined with a double-mixing stopped-flow spectrophotometer. The formation of vitamin C radical was observed in the absorption spectrum. The kinetic effect of methyl substitution on the aromatic ring of vitamin E radical indicates that partial charge-transfer plays a role in the reaction. Since a substantial deuterium kinetic isotope effect was not found, the tunneling effect may not play an important role under the present experimental conditions.
Catalytic antioxidants: Regenerable tellurium analogues of vitamin e
Singh, Vijay P.,Poon, Jia-Fei,Engman, Lars
, p. 6274 - 6277 (2013)
In an effort to improve the chain-breaking capacity of the natural antioxidants, an octyltelluro group was introduced next to the phenolic moiety in β- and δ-tocopherol. The new vitamin E analogues quenched peroxyl radicals more efficiently than α-tocopherol and were readily regenerable by aqueous N-acetylcysteine in a simple membrane model composed of a stirring chlorobenzene/water two-phase system. The novel tocopherol analogues could also mimic the action of the glutathione peroxidase enzymes.
Process of separating chiral isomers of chroman compounds and their derivatives and precursors
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Page/Page column 15, (2012/12/13)
The present invention relates to a process of separating chiral isomers of chroman compounds, particularly tocopherols and tocotrienols as well as the esters and intermediates thereof. It has been found that this process allows a separation of the desired isomer with a higher yield and enables the use of the non-desired isomers in a very efficient way. Said process is particularly useful when implemented in an industrial process. Furthermore, it has been found that this process allows using isomer mixtures as they result from traditional industrial synthesis.
Vitamin E chemistry. Nitration of non-α-tocopherols: Products and mechanistic considerations
Patel, Anjan,Liebner, Falk,Netscher, Thomas,Mereiter, Kurt,Rosenau, Thomas
, p. 6504 - 6512 (2008/02/10)
(Chemical Equation Presented) In contrast to the α-form permethylated at the aromatic ring, non-α-tocopherols possess free aromatic ring positions which enable them to act as potent scavengers of electrophiles in vivo and in vitro. In preparation of enzymatic studies involving peroxynitrite and other nitrating systems, the behavior of non-α-tocopherols under nitration conditions was studied. The nitration products of β-, γ-, and δ-tocopherol were identified, comprehensively analytically characterized, and their structure was supported by X-ray crystal structure analysis on truncated model compounds. Even under more drastic nitration conditions, no erosion of the stereochemistry at 2-C occurred. The nitrosation of γ-tocopherol and δ-tocopherol was re-examined, showing the slow oxidation of the initial nitroso products to the corresponding nitro derivatives by air to be superimposed by a fast equilibrium with the tautomeric ortho-quinone monoxime, which only in the case of γ-tocopherol released hydroxyl amine at elevated temperatures to afford the stable ortho-quinone. Mononitration of δ-tocopherol selectively proceeded at position 5. This selectivity can be explained by the theory of strain-induced bond localization (SIBL) to the quinoid nitration intermediates. Bisnitration was only insignificantly disfavored by the first nitro group, so that under normal nitration conditions offering an excess of nitrating species only the bisnitration product was found.
Tocopherols by hydride reduction of dialkylamino derivatives
Netscher, Thomas,Mazzini, Francesco,Jestin, Roselyne
, p. 1176 - 1183 (2008/02/08)
Aminomethylation with Mannich reagents derived from secondary amines and paraformaldehyde under improved conditions has been used to convert non-α-tocopherol homologues into α-tocopherol, the biologically most important vitamin E compound. Mono- and bis(aminomethylated) β-, γ-and δ-tocopherol were then subsequently transformed into the corresponding tocopherols (α- and β-tocopherol) by reductive deamination. As an alternative to classical catalytic hydrogenation in the last step, efficient laboratory protocols using complex hydrides have been derived and applied to the preparation of labelled vitamin E compounds. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
Biotenside esters and phosphatides with vitamin-D and vitamin-E compounds
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, (2008/06/13)
New biotenside esters and phosphatides formed with Vitamin-D and Vitamin-E compounds possessing a pronounced antitumor activity, processes for their production as well as for the preparation of concentrates and pharmaceutical compositions containing these new esters and phosphatides, and their use for treating tumors are described.
The substrate specificity of tocopherol cyclase
Stocker, Achim,Fretz, Heinz,Frick, Haroun,Ruettimann, August,Woggon, Wolf-Dietrich
, p. 1129 - 1134 (2007/10/03)
The substrate specificity of the enzyme tocopherol cyclase from the blue-green algae Anabaena variabilis (Cyanobacteria) was investigated with 11 substrate analogues revealing the significance of three major recognition sites: (i) the OH group at C(1) of the hydroquinone, (ii) the (E) configuration of the double bond, and (iii) the length of the lipophilic side chain. Experiments with two affinity matrices suggest that substrates approach the enzyme's active site with the hydrophobic tail.
