Conversion of d-α-tocopherol-C14 to tocopheryl-p-quinone in vivo

Csallany, A. Saari; Draper, H. H.; Shah, Swapnil

doi:10.1016/0003-9861(62)90159-5

Cited by 77 publications

(14 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The former hydrolyze to α-tocopherolquinone (TQ), which also is a product of TH oxidation by several other types of oxidants. Several reports indicate that TQ is present in tissues, although the reported levels vary (1)(2)(3)(4)(5)(6)(7)(8)(9). Previous work in our laboratory suggested that much of the TQ formed in tissues is present as the twoelectron reduction product α-tocopherolhydroquinone (TQH 2 ) (10).…”

mentioning

confidence: 93%

Antioxidant reactions of α‐tocopherolhydroquinone

Liebler

Burr

2000

Lipids

View full text Add to dashboard Cite

Alpha-tocopherolhydroquinone (TQH2) is a product of alpha-tocopherol oxidation/reduction that exerts antioxidant effects in biological systems. TQH2 inhibited autoxidation of methyl linoleate initiated by peroxyl radicals derived from thermolysis of 2,2'-azobis(2,4-dimethylvaleronitrile) in acetonitrile. TQH2 oxidation yielded alpha-tocopherolquinone (TQ) as a major product and 2,3-epoxy-alpha-tocopherolquinone and 5,6-epoxy-alpha-tocopherolquinone as minor products. Each TQH2 consumed approximately two peroxyl radicals in the course of the oxidation. The data suggest that TQH2 scavenges peroxyl radicals primarily by electron transfer to form TQ and secondarily by addition-elimination to form the epoxyquinones.

show abstract

mentioning

confidence: 93%

Antioxidant reactions of α‐tocopherolhydroquinone

Liebler

Burr

2000

Lipids

View full text Add to dashboard Cite

show abstract

“…The different distribution of a-TQ (a-Toc) versus UQ is based on biosynthesis of UQ in mitochondria and in the ER/Golgi system [69] while a-TQ is preferably derived from oxidation of a-Toc [30,70]. The intracellular supply with a-Toc in turn is regulated by the a-tocopherol transfer protein [71], whereas a-TQ is preferably bound to the TAP [66], suggesting a transport independent of a-Toc.…”

Section: Distribution Of Tq and Toc In Subcellular Fractionsmentioning

confidence: 97%

Tocopheryl quinones and mitochondria

Gille

Staniek

Rosenau

et al. 2010

Molecular Nutrition Food Res

View full text Add to dashboard Cite

In the past, the role of tocopherols and tocopheryl hydroquinones as antioxidants in mitochondria has been examined. However, structural properties of tocopherols and tocopheryl quinones (arrangement of polar/apolar moieties) have also been recognized as being crucial for the selective transport of RRR-alpha-congeners compared with other tocopherols in the cell, suggesting that these properties might be generally important for the binding of vitamin E-related compounds to proteins and enzymes in mitochondria. Therefore, direct modulation of mitochondrial activities, such as bioenergetics, production of reactive oxygen species and apoptosis, not exclusively related to the redox activity of these compounds is increasingly studied. This overview focuses on the influence of alpha-/gamma-tocopheryl quinones and their parent alpha-/gamma-tocopherols on mitochondrial functions, including formation of tocopheryl quinones, their analytical aspects, their potential as alternative substrates and their inhibitory activity for some mitochondrial functions. It is shown that the understanding of how tocopheryl quinones and tocopherols interfere with mitochondrial functions on the molecular level is still incomplete and that a better comprehension requires further research activities.

show abstract

“…Products formed in vitro, post mortem, or during isolation, must be excluded. Tocopheryl quinone and a dimer of a-tocopherol, first obtained by an in vitro oxidation of a-tocopherol with ferricyanide (140), were considered to be formed in vivo (141,142) when found in rats depleted of vitamin E for one year after administration of labelled a-tocopherol.…”

Section: Vitamin Ementioning

confidence: 99%