?-Tocotrienol and ?-Tocopherol Are Primarily Metabolized to Conjugated 2-(ß-carboxyethyl)-6-Hydroxy-2,7,8-Trimethylchroman and Sulfated Long-Chain Carboxychromanols in Rats1–3  

Oleh:

Freiser, Helene ; Qing, Jiang

Jenis: Article from Journal - ilmiah internasional
Dalam koleksi: JN: The Journal of Nutrition vol. 139 no. 05 (May 2009), page 884-889.
Topik: Nutrient Physiology; Metabolism; and Nutrient-Nutrient Interactions

Ketersediaan

Perpustakaan FK Nomor Panggil: J42.K.2009.02 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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Isi artikel

The metabolism of ?-tocotrienol ( ?-TE) and ?-tocopherol ( ?-T) was investigated in human A549 cells and in rats. Similar to ?-T, A549 cells metabolized ?-TE to sulfated 9'-, 11'-, and 13'-carboxychromanol and their unconjugated counterparts. After 72-h incubation with the cells, 90% of long-chain carboxychromanols in the culture media from ?-TE, but <45% from ?-T, were in the sulfated form. The formation of these metabolites was further investigated in rats gavaged by ?-TE at 10 or 50 mg/kg, ?-T at 10 mg/kg, or tocopherol-stripped corn oil in controls. Six hours after a single dosing, the supplemented rats had increased plasma concentrations of 13'-carboxychromanol and sulfated 9'-, 11'-, 13'-carboxychromanol, whereas none of these metabolites were detectable in the controls. Sulfated 11'-carboxychromanol was the most abundant long-chain metabolite in ?-TE–supplemented rats. Sulfatase/glucuronidase hydrolysis revealed for the first time that >88% 2-(ß-carboxyethyl)-6-hydroxychroman ( -CEHC), the terminal ß-oxidation metabolite, was in the conjugated form in the plasma. In all groups, conjugated -CEHC accounted for >75% of total metabolites, whereas free CEHC was a minor metabolite. At 10 mg/kg, the plasma concentrations of total metabolites from ?-TE–supplemented rats were higher (P < 0.05) than those from ?-T–fed rats. These results demonstrate that in rats, conjugation such as sulfation occurs parallel to ß-oxidation in the liver and is quantitatively important to vitamin E metabolism. Conjugated long-chain carboxychromanols may be novel excreted metabolites during supplementation. Our data also provide in vivo evidence that ?-TE is more extensively metabolized than ?-T.

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