Identification and quantitation of novel vitamin E metabolites, sulfated long-chain carboxychromanols, in human A549 cells and in rats
Identification and quantitation of novel vitamin E metabolites, sulfated long-chain carboxychromanols, in human A549 cells and in rats
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DOI：
10.1194/jlr.d700001-jlr200
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发表时间：
2007-05-01
影响因子：
6.5
通讯作者：
Yin, Xinmin
中科院分区：
文献类型：
--
作者：
Jiang, Qing;Freiser, Helene;Yin, Xinmin
维生素E的代谢涉及植基链的氧化，以通过中间体13 '-羟基色原烷醇和长链羧基色原烷醇的形成产生末端代谢物7，8-二甲基-2-（β-羧乙基）-6-羟基色原烷（CEHC）。以前报告过结合（包括硫酸化）代谢产物，但仅限于CEHC。在这里，使用电喷雾和电感耦合等离子体质谱，我们发现，γ-生育酚（γ-T）和δ-T代谢为硫酸化的9 '，11'，和13-羧基色原烷醇（9'S，11'S，和13'S）在人类A549细胞。为了进一步研究代谢物，我们开发了一种具有荧光检测的HPLC测定法，可同时分析硫酸化和非共轭中间代谢物。使用该测定法，我们发现硫酸化代谢物通过硫酸酯酶消化转化为非共轭羧基色原烷醇。在培养的细胞中，类似于45%来自γ-T的长链羧基色原烷醇，但只有10%来自δ-T的长链羧基色原烷醇被硫酸化。在补充γ-T后，大鼠具有增加的9 ′ S、11 ′ S和13 ′ S）13 ′-羟基色原烷醇、13 ′-羧基色原烷醇和γ-CEHC的组织水平。合并硫酸化长链代谢物的血浆浓度与CEHC相当或超过CEHC，并随γ-T补充剂量成比例增加。我们的研究确定了硫酸化长链羧基色原烷醇作为新型维生素E代谢物，并提供了硫酸化可能与β-氧化平行发生的证据。此外，HPLC荧光分析法是研究维生素E代谢的有用工具。
The metabolism of vitamin E involves oxidation of the phytyl chain to generate the terminal metabolite 7,8-dimethyl- 2-(beta-carboxyethyl)-6-hydroxychroman (CEHC) via intermediate formation of 13'- hydroxychromanol and long-chain 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 -gamma-tocopherol (gamma-T) and delta-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, similar to 45% long-chain carboxychromanols from gamma-T but only 10% from delta-T were sulfated. Upon supplementation with gamma-T, rats had increased tissue levels of 9'S, 11'S, and 13'S) 13'-hydroxychromanol, 13'-carboxychromanol, and gamma-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 gamma-T. Our study identifies sulfated long-chain carboxychromanols as novel vitamin E metabolites and provides evidence that sulfation may occur parallel with beta-oxidation. In addition, the HPLC fluorescence assay is a useful tool for the investigation of vitamin E metabolism.