Cited by 49Antioxidant Activity and Oxidative StressExercise and Physiological ResponsesRedox biology and oxidative stress

Antioxidant action of vitamin E in vivo as assessed from its reaction products with multiple biological oxidants

Niki, Etsuo, Noguchi, Noriko·2021·Free Radical Research

Abstract

Vitamin E acts as essential antioxidant against detrimental oxidation of biological molecules induced by multiple reactive species. To gain more insight into the physiological role of vitamin E, the levels of its oxidation products in humans under normal and pathological conditions were compared. α-Tocopherol quinone (α-TQ) and 5-nitro-γ-tocopherol (5-NgT) were focused. α-TQ is produced by multiple oxidants including oxygen radicals, peroxynitrite, hypochlorite, singlet oxygen, and ozone, while 5-NgT is produced by nitrogen dioxide radical derived from peroxynitrite and the reaction of nitrite and hypochlorite. The reported concentrations of α-TQ and 5-NgT in healthy human plasma are highly variable ranging from 15 to 360 and 4 to 170 nM, respectively. In general, the molar ratio 5-NgT/γ-tocopherol was higher than the ratio α-TQ/α-tocopherol. Both absolute concentrations of α-TQ and 5-NgT and the molar ratios to the parent tocopherols were elevated significantly in the plasma of patients with various diseases compared with healthy subjects except neurological diseases. The molar ratios of the products to the respective parent compounds decreased in the order of 5-NgT/γ-tocopherol > α-TQ/α-tocopherol > hydroxyoctadecadienoate/linoleate > 3-nitrotyrosine/tyrosine > isoprostane/arachidonate. The molar ratios of nitrated products to the respective parent compounds in human plasma are approximately 10−2 for 5-NgT and 10−5 for 3-nitrotyrosine, nitro-oleic acid, and 8-nitroguaine. These data indicate that vitamin E acts as an important physiological antioxidant and that α-TQ and 5-NgT represent biomarker for oxidative stress and nitrative stress respectively.

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Crossref · 10.1080/10715762.2020.1866181

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  • Further studies documented the oxidation of vitamin E after the attack of ROS, however, the oxidation of vitamin E has not provided protection against lipids or damage to other biomolecules associated with chronic diseases.

    “Further studies documented the oxidation of vitamin E after the attack of ROS, however, the oxidation of vitamin E has not provided protection against lipids or damage to other biomolecules associated with chronic diseases (Niki and Noguchi 2021).”

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Authors
Niki, E., & Noguchi, N.
Affiliations
  • Research Center for Advanced Science and Technology, The University of Tokyo (JP)
  • Doshisha University (JP)
Corresponding author
Niki, Etsuo
Venue
Free Radical Research
Published
2021-01-11
Volume
55
Issue
4
Pages
352-363
ISSN
  • 1029-2470 (ISSN-L)
  • 1071-5762
OpenAlex
W3112342006
Cited by
47
References
121
Citations by year
2026: 6 · 2025: 5 · 2024: 12 · 2023: 8 · 2022: 11 · 2021: 5
FWCI
0.52
Type
journal article
Language
en
Open access
closed
Locations
  • Free Radical Research (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Biochemistry › Antioxidant Activity and Oxidative Stress
  • Health Sciences › Medicine › Rehabilitation › Exercise and Physiological Responses
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Redox biology and oxidative stress
Keywords
vitamin E, tocopherol oxidation, oxidative stress, nitrative stress, peroxynitrite, hypochlorite, reactive oxygen species, plasma biomarkers, nitrotyrosine, isoprostanes, nitro-oleic acid, 8-nitroguanine, linoleate
MeSH terms
Antioxidants, Humans, Vitamin E, Molecular Structure, Oxidants, gamma-Tocopherol

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