Regeneration of vitamin E in human platelets.

Chan, Alvin C.; Tran, Khai; Raynor, Tina; Ganz, Peter; Chow, Ching K.

doi:10.1016/s0021-9258(19)47372-9

Cited by 86 publications

(6 citation statements)

References 37 publications

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“…Although 8a-hydroxytocopherone appeared to be the ascorbic acid-reducible intermediate in our experiments, Chan et al (1991) recently suggested that -T* was the ascorbic acid-and NDGA-reducible product formed by -TH oxidation in platelet homogenates. However, -T* and the reducible product in our experiments exhibt quite different properties.…”

Section: Discussioncontrasting

confidence: 58%

“…The above results suggest that 8a-hydroxytocopherone ( 5) is the ascorbic acid-reducible intermediate. We tested this hypothesis further by examining the pH dependence of regeneration and the effectiveness of NDGA, which has been reported to regenerate -TH oxidized in human platelet homogenates (Chan et al, 1991). We had observed previously that in acetonitrile/buffer mixtures, 8a-hydroxytocopherone (5) was reduced more efficiently at pH 3 than at pH 7 (Liebler etal., 1989).…”

Section: Stability Of 8a-(alkyldioxy)tocopherones In Liposomementioning

confidence: 98%

“…For example, Leedle and Aust (1990) reported that -TH recovery was increased when peroxidized microsomal lipids were extracted in the presence of ascorbic acid. Chan et al (1991) reported that -TH consumed during peroxidation of human platelet homogenates was partially regenerated by ascorbic acid, NDGA, or glutathione addition to the oxidized homogenates. Regeneration also occurred when ascorbic acid or NDGA, but not glutathione, was added to ethanol-denatured homogenates.…”

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confidence: 99%

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Oxidation of vitamin E during iron-catalyzed lipid peroxidation: evidence for electron-transfer reactions of the tocopheroxyl radical

Liebler¹,

Burr²

1992

Biochemistry

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Incubation of phosphatidylcholine liposomes containing the biological antioxidant alpha-tocopherol (alpha-TH) with xanthine, xanthine oxidase, and FeCl2 caused alpha-TH oxidation to alpha-tocopherol quinone (alpha-TQ) and 8a-hydroperoxytocopherone (2). In addition, 4a,5-epoxy-8a-hydroperoxytocopherone (3), 7,8-epoxy-8a-hydroperoxytocopherone (4), and their respective hydrolysis products 2,3-epoxy-alpha-tocopherol quinone (6) and 5,6-epoxy-alpha-tocopherol quinone (7) also were formed. alpha-TQ was the major product at less than 20% alpha-TH oxidation, whereas epoxides were the predominant products when alpha-TH was more extensively oxidized. 8a-(Alkyldioxy)tocopherones 1, which are formed when peroxyl radicals oxidize alpha-TH in other systems and which are precursors to alpha-TQ, were not found. 8a-Hydroxytocopherone (5), rather than 8a-(alkyldioxy)tocopherones 1, appeared to be the precursor to alpha-TQ. Approximately 30% of the alpha-TH consumed was regenerated by treatment of samples with ascorbic acid or nordehydroguaiaretic acid (NDGA) at pH 3, but not at pH 7. The stability of the ascorbic acid- and NDGA-reducible species and pH dependence for regeneration matched those of 8a-hydroxytocopherone (5) and contrasted with the properties of the tocopheroxyl radical (alpha-T.). Incubation of liposomes containing alpha-TH with the diphenylpicrylhydrazyl (DPPH) radical, which oxidizes alpha-TH to alpha-T. in high yield, formed an ascorbic acid-reducible species with properties identical to those of compound 5. The results indicate that phospholipid peroxyl radicals oxidize alpha-T. to epoxides, 8a-hydroperoxytocopherone (2), and the tocopherone cation (alpha-T+), which hydrolyzes to 5, the immediate precursor to alpha-TQ.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Discussioncontrasting

confidence: 58%

Section: Stability Of 8a-(alkyldioxy)tocopherones In Liposomementioning

confidence: 98%

mentioning

confidence: 99%

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Oxidation of vitamin E during iron-catalyzed lipid peroxidation: evidence for electron-transfer reactions of the tocopheroxyl radical

Liebler¹,

Burr²

1992

Biochemistry

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“…Flavonoids also possess TH-repairing activity in human low densitity lipoprotein (). Ascorbic acid, glutathione, and green tea catechins have also evidenced a regeneration of TH ( − ). The possible regeneration of TH observed in this work seems to be associated to the presence of phenolic antioxidants when TH is partly oxidized.…”

Section: Resultsmentioning

confidence: 98%

α-Tocopherol Oxidation in Fish Muscle during Chilling and Frozen Storage

Pazos

Sánchez

Medina

2005

J. Agric. Food Chem.

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The oxidation of alpha-tocopherol (TH) in chilled and frozen fish muscle was determined using high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry. TH oxidation byproducts were identified as alpha-tocopherolquinone (TQ), 5,6-epoxy-alpha-tocopherolquinone (TQE1), and 2-3-epoxy-alpha-tocopherolquinone (TQE2). The concentration of TH decreased significantly during storage while those of TQ, TQE1, and TQE2 increased noteworthy. The relative amounts of TH and its oxidized products were significantly related with the extent of oxidation produced in postmortem fish, and the ratio TQ/TH is suggested as an index of oxidative stress in fish muscle. The effect of phenolic antioxidants supplementation on retarding TH oxidation was also studied. Data suggested that the addition of 100 ppm of caffeic acid, hydroxytyrosol, and propyl gallate could regenerate endogenous TH from its oxidized forms resulting in an antioxidant synergy consistent with the reduction of lipid oxidation observed in fish muscle supplemented with phenolic compounds.

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“…Experiments using cultured cells have provided evidence that VC spares VE (10; 11; 12) . Further, sparing of VE by VC in human low-density lipoproteins (LDL) (13) , erythrocytes (14) , and platelets (15) has also been indicated in vitro studies. Similar observations have been made in fish (16) .…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Determination of tissue-specific interaction between vitamin C and vitamin Ein vivousing senescence marker protein-30 knockout mice as a vitamin C synthesis deficiency model

et al. 2021

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Vitamin E (α-tocopherol; VE) is known to be regenerated from VE radicals by vitamin C (L-ascorbic acid; VC) in vitro. However, their in vivo interaction in various tissues is still unclear. Therefore, we alternatively examined the in vivo interaction of VC and VE by measurement of their concentrations in various tissues of senescence marker protein-30 (SMP30) knockout (KO) mice as a VC synthesis deficiency model. Male SMP30-KO mice were divided into four groups (VC+/VE+, VC+/VE–, VC–/VE+ and VC–/VE–), fed diets with or without 500 mg/kg VE and given water with or without 1·5 g/l VC ad libitum. Then, VC and VE concentrations in the plasma and various tissues were determined. Further, gene expression levels of transporters associated with VC and VE, such as α-tocopherol transfer protein (α-TTP) and sodium-dependent vitamin C transporters (SVCTs), were examined. These results showed that the VE levels in the VC-depleted (VC–/VE+) group were significantly lower than those in the VC+/VE+ group in the liver and heart; the VC levels in the VE-depleted (VC+/VE–) group were significantly lower than those in the VC+/VE+ group in the kidneys. The α-TTP gene expression in the liver and kidneys was decreased by VC and/or VE depletion. Moreover, SVCT1 gene expression in the liver was decreased by both VC and VE depletion. In conclusion, these results indicate that VC spares VE mainly in the liver and heart and that VE spares VC in the kidneys of SMP30-KO mice. Thus, interaction between VC and VE is likely to be tissue specific.

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Regeneration of vitamin E in human platelets.

Cited by 86 publications

References 37 publications

Oxidation of vitamin E during iron-catalyzed lipid peroxidation: evidence for electron-transfer reactions of the tocopheroxyl radical

Oxidation of vitamin E during iron-catalyzed lipid peroxidation: evidence for electron-transfer reactions of the tocopheroxyl radical

α-Tocopherol Oxidation in Fish Muscle during Chilling and Frozen Storage

Determination of tissue-specific interaction between vitamin C and vitamin Ein vivousing senescence marker protein-30 knockout mice as a vitamin C synthesis deficiency model

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