Analysis of plasma tocopherols α, γ, and 5-nitro-γ in rats with inflammation by HPLC coulometric detection

Christen, Stephan; Jiang, Qing; Shigenaga, Mark K.; Ames, Bruce N.

doi:10.1194/jlr.d200023-jlr200

Cited by 45 publications

(29 citation statements)

References 30 publications

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“…The nitration of Á-tocopherol is not affected by the simultaneous presence of ·-tocopherol, suggesting that the two forms complement each other [103]. The same group showed in an animal study with Fischer 344 rats that the 5-nitro-Á-tocopherol levels were 2-fold higher compared to the fasted control after intraperitoneal injection of zymosan, when adjusted to Á-tocopherol [98]. This result demonstrates that nitration of Á-tocopherol is increased under inflammatory conditions and highlighted the importance of reactive nitrogen oxide species reactions in the lipid phase.…”

Section: Chemistry Of á-Tocopherol Relevant To Biological Activitiesmentioning

confidence: 59%

“…Chronic inflammation induced by the activation of phagocytes is one of the major contributors to the development of cancer, cardiovascular diseases or neurodegenerative disorders [96,97]. Reactive nitrogen oxygen species were shown to contribute to this damage since their stable end products, nitrite and nitrate, were detected in animals and humans with ongoing inflammation [98].…”

Section: Chemistry Of á-Tocopherol Relevant To Biological Activitiesmentioning

confidence: 99%

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Gamma-Tocopherol – An Underestimated Vitamin?

2004

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The main research activities of the last decades on tocopherols were mainly focused on α-tocopherol, in particular when considering the biological activities. However, recent studies have increased the knowledge on γ-tocopherol, which is the major form of vitamin E in the diet in the USA, but not in Europe. γ-Tocopherol provides different antioxidant activities in food and in-vitro studies and showed higher activity in trapping lipophilic electrophiles and reactive nitrogen and oxygen species. The lower plasma levels of γ- compared to α-tocopherol might be discussed in the light of different bioavailability, but also in a potential transformation from γ- into α-tocopherol. From the metabolism end product, only that of γ-tocopherol (2,7,8-trimethyl-2-(β-carboxyethyl)-6-hydroxychroman), but not that of α-tocopherol, was identified to provide natriuretic activity. Studies also indicate that only the γ-tocopherol plasma level served as biomarker for cancer and cardiovascular risk. Therefore, this paper provides a comprehensive review on γ-tocopherol with emphasis on its chemistry, biosynthesis, occurrence in food, different intake linking to different plasma levels in USA and Europe, absorption and metabolism, biological activities, and possible role in human health.

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Section: Chemistry Of á-Tocopherol Relevant To Biological Activitiesmentioning

confidence: 59%

Section: Chemistry Of á-Tocopherol Relevant To Biological Activitiesmentioning

confidence: 99%

Gamma-Tocopherol – An Underestimated Vitamin?

2004

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“…a-T and g-T were measured by HPLC assay with electrochemical detection (18). Briefly, tocopherols were extracted from plasma or tissue homogenates using a mixture of methanol and hexane (2:5, v/v) as described (19,20).…”

Section: Quantitation Of Tocopherolsmentioning

confidence: 99%

Identification and quantitation of novel vitamin E metabolites, sulfated long-chain carboxychromanols, in human A549 cells and in rats

Jiang

Freiser

Wood

et al. 2007

Journal of Lipid Research

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The metabolism of vitamin E involves oxidation of the phytyl chain to generate the terminal metabolite 7,8-dimethyl-2-(b-carboxyethyl)-6-hydroxychroman (CEHC) via intermediate formation of 13 ¶-hydroxychromanol and longchain carboxychromanols. Conjugated (including sulfated) metabolites were reported previously but were limited to CEHCs. Here, using electrospray and inductively coupled plasma mass spectrometry, we discovered that g-tocopherol (g-T) and d-T were metabolized to sulfated 9 ¶-, 11 ¶-, and 13 ¶-carboxychromanol (9 ¶S, 11 ¶S, and 13 ¶S) in human A549 cells. To further study the metabolites, we developed a HPLC assay with fluorescence detection that simultaneously analyzes sulfated and nonconjugated intermediate metabolites.Using this assay, we found that sulfated metabolites were converted to nonconjugated carboxychromanols by sulfatase digestion. In cultured cells, ?45% long-chain carboxychromanols from g-T but only 10% from d-T were sulfated. Upon supplementation with g-T, rats had increased tissue levels of 9 ¶S, 11 ¶S, and 13 ¶S, 13 ¶-hydroxychromanol, 13 ¶-carboxychromanol, and g-CEHC. The plasma concentrations of combined sulfated long-chain metabolites were comparable to or exceeded those of CEHCs and increased proportionally with the supplement dosages of g-T. Our study identifies sulfated long-chain carboxychromanols as novel vitamin E metabolites and provides evidence that sulfation may occur parallel with b-oxidation. In addition, the HPLC fluorescence assay is a useful tool for the investigation of vitamin E metabolism.-Jiang, Q., H. Freiser, K. V. Wood, and X. Yin. Identification and quantitation of novel vitamin E metabolites, sulfated long-chain carboxychromanols, in human A549 cells and in rats. J. Lipid Res. or y-T) and four corresponding tocotrienols] (Scheme 1). All of these molecules have a chromanol ring and a 16 carbon phytyl chain, which are responsible for the potent antioxidant activity and lipophilic property, respectively. Despite structural similarity, different vitamin E forms appear to have distinct bioactivity and to be distinctively metabolized (1, 2). a-T is the predominant vitamin E form in tissues and is the least catabolized. On the other hand, some portions of non-a forms are likely to be readily metabolized and/or excreted directly via the bile (3), because they do not appear to be accumulated to the same extent as a-T in most tissues. To elucidate the potential biological functions of each vitamin E form, it is important to understand their metabolism and to identify the major metabolites in the body.The understanding of how vitamin E is metabolized was initiated by the identification of their urine-excreted metabolites. The water-soluble metabolite of y-T, y-7,8-dimethyl-2-(b-carboxyethyl)-6-hydroxychroman (CEHC), was first found in rat urine (4) (Scheme 1). Subsequently, g-CEHC and a-CEHC were identified to be the major urine-excreted metabolites of g-T and a-T, respectively (5-9). g-CEHC has been shown to have natriuretic activity (9) and to inhibit t...

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“…For a-Toc many different reversed-phase HPLC separation methods based on fluorimetric [45], and electrochemical detection [46][47][48] as well as GC/MS [49], and LC/MS [50] spectroscopic methods exist. These methods are widely used for Toc analysis in biological samples.…”

Section: Separation and Detection Methodsmentioning

confidence: 99%

Tocopheryl quinones and mitochondria

Gille

Staniek

Rosenau

et al. 2010

Molecular Nutrition Food Res

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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.

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Analysis of plasma tocopherols α, γ, and 5-nitro-γ in rats with inflammation by HPLC coulometric detection

Cited by 45 publications

References 30 publications

Gamma-Tocopherol – An Underestimated Vitamin?

Gamma-Tocopherol – An Underestimated Vitamin?

Identification and quantitation of novel vitamin E metabolites, sulfated long-chain carboxychromanols, in human A549 cells and in rats

Tocopheryl quinones and mitochondria

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