Tadahiko Ueda

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In this study, we investigated a change in the excretory content of 2,7,8-trimethyl-2(2′-carboxyethyl)-6-hydroxychroman (γ-CEHC), a γ-tocopherol (γ-Toc) metabolite, in rat urine and bile by using a new high-performance liquid chromatography-elelectrochemical detection (HPLC-ECD) method. In this determination, CEHC [α- and γ-CEHC, where(More)
2,7,8-Trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman (gamma-CEHC), a metabolite of gamma-tocopherol and gamma-tocotrienol, was identified as a new endogenous natriuretic factor. However, gamma-tocopherol and gamma-tocotrienol, both precursors of gamma-CEHC, have never directly been observed to have natriuretic potency. Thus, we investigated whether(More)
We established a method to simultaneously determine RRR- and SRR-α-tocopherol (α-Toc) and their quinones in biological samples by chiral-phase high-performance liquid chromatography (HPLC). α-Toc had a shorter retention time than α-tocopherylquinones (α-TQ), and 2-ambo-α-Toc was completely separated into two peaks; the first peak was RRR-α-Toc and the(More)
We have previously reported that gamma-tocopherol (gamma-Toc) displays a natriuretic potency in rats fed a NaCl diet and administered 20 mg gamma-Toc. In this study, we investigated whether gamma-Toc has natriuretic potency at a dose lower or higher than 20 mg in rats given a NaCl diet. Male rats were fed a control diet or a NaCl diet and administered(More)
Endogenous natriuretic factors are believed to be responsible for extracellular fluid homeostasis in mammals. A new endogenous natriuretic factor, Loma Linda University-alpha (LLU-alpha) has recently been proven to be a 2,7,8-trimethyl-2-(2'-carboxyethyl)-6-hydroxychroman (gamma-CEHC), which is a metabolite of gamma-tocopherol (gamma-Toc). The purpose of(More)
We investigated the distribution and metabolism of SRR a -tocopherol ( SRR a -Toc), synthetic a -Toc compared with RRR a -Toc, in rats after a single oral administration of 2 mg (20 m Ci) SRR and RRR a -[5-methyl14 C]Toc. In the liver, there was no difference in the recovery of radioactivity until 12 h after administration, and it reached a maximum of 4.4%(More)
Synthetic α-tocopherol (α-Toc) contains equal amounts of eight different stereoisomers, and the four stereoisomers with the 2R configuration are generally more active than their correspoding 2S-isomers. We investigated the biodiscrimination of α-Toc stereoisomers during intestinal absorptionin situ andin vitro. Intestinal absorption of α-Toc stereoisomers(More)
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