Vitamin E: A vitamin still awaiting the detection of its biological function

Brigelius‐Flohé, Regina; Galli, Francesco

doi:10.1002/mnfr.201000091

Cited by 53 publications

(39 citation statements)

References 29 publications

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“…On the basis of the concentration of vitamins C and E at the study entry, it is clear that none of the subjects in the current study had hypovitaminosis. Moreover, it is worth mentioning that even the in vivo radical scavenging activity of vitamin E is currently strongly debated (45,46).…”

Section: Blood and Muscle Redox Statusmentioning

confidence: 99%

No effect of antioxidant supplementation on muscle performance and blood redox status adaptations to eccentric training

Theodorou

Nikolaidis²,

Paschalis³

et al. 2011

The American Journal of Clinical Nutrition

121

132

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Background: It was recently reported that antioxidant supplementation decreases training efficiency and prevents cellular adaptations to chronic exercise. Objective: This study aimed to investigate the effects of vitamin C and vitamin E supplementation on muscle performance, blood and muscle redox status biomarkers, and hemolysis in trained and untrained men after acute and chronic exercise. A specific type of exercise was applied (eccentric) to produce long-lasting and extensive changes in redox status biomarkers and to examine more easily the potential effects of antioxidant supplementation. Design: In a double-blinded fashion, men received either a daily oral supplement of vitamin C and vitamin E (n = 14) or placebo (n = 14) for 11 wk (started 4 wk before the pretraining exercise testing and continued until the posttraining exercise testing). After baseline testing, the subjects performed an eccentric exercise session 2 times/ wk for 4 wk. Before and after the chronic eccentric exercise, the subjects underwent one session of acute eccentric exercise, physiologic measurements were performed, and blood samples and muscle biopsy samples (from 4 men) were collected. Results: The results failed to support any effect of antioxidant supplementation. Eccentric exercise similarly modified muscle damage and performance, blood redox status biomarkers, and hemolysis in both the supplemented and nonsupplemented groups. This occurred despite the fact that eccentric exercise induced marked changes in muscle damage and performance and in redox status after exercise. Conclusion: The complete lack of any effect on the physiologic and biochemical outcome measures used raises questions about the validity of using oral antioxidant supplementation as a redox modulator of muscle and redox status in healthy humans.

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Section: Blood and Muscle Redox Statusmentioning

confidence: 99%

No effect of antioxidant supplementation on muscle performance and blood redox status adaptations to eccentric training

Theodorou

Nikolaidis²,

Paschalis³

et al. 2011

The American Journal of Clinical Nutrition

121

132

View full text Add to dashboard Cite

show abstract

“…For instance, vitamin C, beyond its celebrated antioxidant activity, has been implicated as cofactor in several metabolic pathways, such as the synthesis of noradrenaline and carnitine, the post-translational modification of collagen, the catabolism of tyrosine, the calcium management in bones and a wide spectrum of immune-related processes [45,46,47,48]. Likewise, vitamin E exerts many non-antioxidants activities (predominately the α-tocopherol isoform) including modulation of gene expression, inhibition of smooth muscle cell proliferation, preservation of endothelial integrity as well as inhibition of platelet and monocyte-endothelial adhesion [49,50,51,52,53]. On this basis, a challenging question is whether the outcomes of a combined "antioxidant" intervention with vitamins C and E are mediated by their redox or non-redox properties.…”

Section: The Non-antioxidant Effects Of Antioxidantsmentioning

confidence: 99%

Antioxidants as therapeutics in the intensive care unit: Have we ticked the redox boxes?

Margaritelis

2016

Pharmacological Research

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“…The a-tocopherol is the only form that is maintained in human plasma and is the more abundant form found in nature and in human tissues (Brigelius-Flohé and Galli 2010). After passing to the liver, only a-tocopherol appears in the plasma due to its specific selection by the hepatic a-tocopherol transfer protein (a-TTP).…”

Section: Introductionmentioning

confidence: 99%

γ-Tocopherol inhibits human prostate cancer cell proliferation by up-regulation of transglutaminase 2 and down-regulation of cyclins

et al. 2012

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To establish a system to study differentiation therapy drugs, we used the androgen-independent human prostate PC-3 tumor cell line as a target and α- and γ-tocopherol as inducers. Effects of α- and γ-tocopherol on the cell cycle, proliferation and differentiation, were examined. A more significant growth inhibition activity for γ- than for α-tocopherol was observed. Flow cytometry analysis of α- and γ-tocopherol-treated prostate carcinoma PC3 cells showed decreased progression into the S-phase. This effect, particularly evident for γ-tocopherol, was associated with an up-regulation and increased activity of transglutaminase 2 (TG2), a reduced DNA synthesis and a remarkable decreased levels of cyclin D1 and cyclin E. Activation of TG2 suggests that γ-tocopherol has an evident differentiative capacity on PC3 cells, leading to an increased expression of TG2, and reduced cyclin D1 and cyclin E levels, affecting cell cycle progression. It is feasible that up-regulation and activation of TG2, associated with a reduced proliferation, are parts of a large-scale reprogramming that can attenuate the malignant phenotype of PC3 cells in vitro. These data suggest further investigation on the potential use of this γ-form of vitamin E as a differentiative agent, in combination with the common cytotoxic treatments for prostate cancer therapy.

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Vitamin E: A vitamin still awaiting the detection of its biological function

Cited by 53 publications

References 29 publications

No effect of antioxidant supplementation on muscle performance and blood redox status adaptations to eccentric training

No effect of antioxidant supplementation on muscle performance and blood redox status adaptations to eccentric training

Antioxidants as therapeutics in the intensive care unit: Have we ticked the redox boxes?

γ-Tocopherol inhibits human prostate cancer cell proliferation by up-regulation of transglutaminase 2 and down-regulation of cyclins

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