Antioxidant reactions of α‐tocopherolhydroquinone

Liebler, D.C.; Burr, Jeanne A.

doi:10.1007/s11745-000-0617-8

Cited by 27 publications

(14 citation statements)

References 21 publications

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“…Oxidation of α‐TQ in methyl linoleate (in the presence of stable radicals, oxygen atmosphere) led to 9‐hydroxy‐α‐tocopherone, along with other oxidation products . Spectral data as well as extinction coefficients of 9‐hydroxy‐α‐tocopherone agreed with those, published in the literature .…”

Section: Resultssupporting

confidence: 80%

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Synthesis and analysis of tocopheryl quinone and tocopherol esters with fatty acids in heated sunflower oil

Kreps

Kyselka

Burčová

et al. 2015

Euro J Lipid Sci & Tech

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This work focuses on degradation of α‐tocopherol and formation of α‐tocopherol degradation products in sunflower oil heated at frying temperature. We determined the content and measured the kinetics of α‐tocopherol, α‐tocopheryl quinone, α‐tocopheryl fatty acid formation in heated sunflower oil without aeration (So) and in aerated oil (air flow 20 L/h) (SoAir). During 10 h of So oil heating, the α‐tocopherol was depleted and the content of α‐tocopheryl quinone in So grew from 3 to 84 mg/kg, as did the content of tocopherol free fatty acid esters from the initial 5 to 185 mg/kg. In SoAir oil, the rate constants of formation and decomposition of tocopherol degradation products were determined. Accelerated oxidation in SoAir caused depletion of the degradation products of tocopherol after 2 h of heating. The reason for this was significant oxidation and polymerization of fatty acids in SoAir oil. The unique features of this work are the syntheses and spectral analysis of tocopherol oxidation products and the development of a suitable method for quantitative analysis of α‐tocopheryl fatty acids. For the first time, we confirmed formation and degradation of tocopheryl fatty acids during oil heating at frying temperature. Practical applications: All the results presented here, consisting of organic syntheses, qualitative and quantitative analysis of α‐tocopheryl fatty acids as well as oxidation and degradation products of tocopherols and fatty acids, will aid future research focused on the degradation of tocopherols. So far the content of α‐tocopheryl fatty acids has not been determined by GC‐FID or HPLC‐UV. This is why there has been little interest in α‐tocopheryl fatty acids, although they are formed both in culinary treatment of food and in oil refining. Free fatty acids (FFAs), fatty acids (FAs), oxidation [o], products (i) and products (ii) are unspecified products of α‐tocopheryl FAs and α‐TQ degradation. Degradation products of α‐tocopherol were formed in heated sunflower oil and further heating of oil caused decomposition of α‐tocopherol degradation products.

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Section: Resultssupporting

confidence: 80%

“…Our experience and literature data formed the basis of 9‐hydroxy‐α‐tocopherone synthesis. α‐Tocopheryl quinone and stable radicals (AAPH and AIBN, respectively) were dissolved in benzene, methyl linoleate.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and analysis of tocopheryl quinone and tocopherol esters with fatty acids in heated sunflower oil

Kreps

Kyselka

Burčová

et al. 2015

Euro J Lipid Sci & Tech

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“…Singlet oxygen quenching by tocopherols is highly efficient, and it is estimated that a single a-tocopherol molecule can neutralize up to 120 singlet oxygen molecules in vitro before being degraded (Fukuzawa et al, 1982). Because of their chromanol ring structure, tocopherols are capable of donating a single electron to form the resonance-stabilized tocopheroxyl radical (Liebler, 1993;KamalEldin and Appelqvist, 1996), which contrasts with other phenolic antioxidants, such as hydroxyquinones, that must donate two electrons to attain a stable structure (Liebler and Burr, 2000). Tocopheroxyl radicals can also donate a second electron, resulting in opening of the chromanol ring to form the corresponding tocopherol quinone and other oxidized derivatives, which can also participate in electron transfer reactions (Liebler, 1998;Wang and Quinn, 2000).…”

Section: Introductionmentioning

confidence: 99%

Vitamin E Is Essential for Seed Longevity and for Preventing Lipid Peroxidation during Germination

et al. 2004

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Tocopherols (vitamin E) are lipophilic antioxidants synthesized by all plants and are particularly abundant in seeds. Despite cloning of the complete suite of tocopherol biosynthetic enzymes and successful engineering of the tocopherol content and composition of Arabidopsis thaliana leaves and seeds, the functions of tocopherols in plants have remained elusive. To address this issue, we have isolated and characterized two VITAMIN E loci (VTE1 and VTE2) in Arabidopsis that when mutated result in tocopherol deficiency in all tissues. vte1 disrupts tocopherol cyclase activity and accumulates a redoxactive biosynthetic intermediate, whereas vte2 disrupts homogentisate phytyl transferase activity and does not accumulate pathway intermediates. Mutations at either locus cause significantly reduced seed longevity compared with the wild type, indicating a critical role for tocopherols in maintaining viability during quiescence. However, only vte2 mutants exhibited severe seedling growth defects during germination and contained levels of lipid hydroperoxides and hydroxy fatty acids elevated up to 4-and 100-fold, respectively, relative to the wild type. These data demonstrate that a primary function of tocopherols in plants is to limit nonenzymatic lipid oxidation during seed storage, germination, and early seedling development. The vte mutant phenotypes also explain the strong selection for retention of tocopherol biosynthesis during the evolution of seed-bearing plants.

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“…Tocopherols scavenge a variety of reactive oxygen species (ROS) and free radicals and can quench singlet oxygen (Fukuzawa et al, 1982;Brigelius-Flohe and Traber, 1999;Wang and Quinn, 2000). The chromanol ring of tocopherol allows the donation of a hydrogen atom while maintaining a resonance-stabilized configuration (Liebler, 1993;KamalEldin and Appelqvist, 1996); other aromatic antioxidants must donate two hydrogen atoms to attain a stable state (Liebler and Burr, 2000). Donation of a hydrogen atom generates a tocopherol radical, which can be recycled back to the original tocopherol by direct interaction with ascorbate or another reductant (Liebler, 1993).…”

Section: Introductionmentioning

confidence: 99%

Nonenzymatic Lipid Peroxidation Reprograms Gene Expression and Activates Defense Markers inArabidopsisTocopherol-Deficient Mutants

et al. 2006

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Tocopherols (vitamin E) are lipophilic antioxidants that are synthesized by all plants and are particularly abundant in seeds. Two tocopherol-deficient mutant loci in Arabidopsis thaliana were used to examine the functions of tocopherols in seedlings: vitamin e1 (vte1), which accumulates the pathway intermediate 2,3-dimethyl-5-phytyl-1,4-benzoquinone (DMPBQ); and vte2, which lacks all tocopherols and pathway intermediates. Only vte2 displayed severe seedling growth defects, which corresponded with massively increased levels of the major classes of nonenzymatic lipid peroxidation products: hydroxy fatty acids, malondialdehyde, and phytoprostanes. In the absence of pathogens, the phytoalexin camalexin accumulated in vte2 seedlings to levels 100-fold higher than in wild-type or vte1 seedlings. Similarly, gene expression profiling in wild-type, vte1, and vte2 seedlings indicated that increased levels of nonenzymatic lipid peroxidation in vte2 corresponded to increased expression of many defense-related genes, which were not induced in vte1. Both biochemical and transcriptional analyses of vte2 seedlings indicate that nonenzymatic lipid peroxidation plays a significant role in modulating plant defense responses. Together, these results establish that tocopherols in wild-type plants or DMPBQ in vte1 plants limit nonenzymatic lipid peroxidation during germination and early seedling development, thereby preventing the inappropriate activation of transcriptional and biochemical defense responses.

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Antioxidant reactions of α‐tocopherolhydroquinone

Cited by 27 publications

References 21 publications

Synthesis and analysis of tocopheryl quinone and tocopherol esters with fatty acids in heated sunflower oil

Synthesis and analysis of tocopheryl quinone and tocopherol esters with fatty acids in heated sunflower oil

Vitamin E Is Essential for Seed Longevity and for Preventing Lipid Peroxidation during Germination

Nonenzymatic Lipid Peroxidation Reprograms Gene Expression and Activates Defense Markers inArabidopsisTocopherol-Deficient Mutants

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