QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (Publish Ahead of Print[PDF]) Online Supplemental Material All Versions of this Article: 139/5/884    most recent jn.108.103309v1 Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Freiser, H. Articles by Jiang, Q. Search for Related Content PubMed PubMed Citation Articles by Freiser, H. Articles by Jiang, Q.

---

Nutrient Physiology, Metabolism, and Nutrient-Nutrient Interactions

-Tocotrienol and -Tocopherol Are Primarily Metabolized to Conjugated 2-(β-carboxyethyl)-6-Hydroxychroman and Sulfated Long-Chain Carboxychromanols in Rats^1,2,3

Department of Foods and Nutrition, Interdepartmental Nutrition Program, Purdue University, West Lafayette, IN 47907

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-(β-carboxyethyl)-6-hydroxychroman (-CEHC), the terminal β-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 β-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.

^* To whom correspondence should be addressed. E-mail: qjiang{at}purdue.edu.

Manuscript received 8 December 2008. Initial review completed 12 December 2008. Revision accepted 10 February 2009.