1995 Fiscal Year Final Research Report Summary
IN VIVO DISTRIBUTION AND BIODISCRIMINATION OF alpha-TOCOPHEROL STEREOISOMERS
| Project/Area Number |
06660152
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
食品科学・栄養科学
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| Research Institution | OCHANOMIZU UNIVERSITY |
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Principal Investigator |
IGARASHI Osamu OCHANOMIZU UNIVERSITY INSTITUTE OF ENVIRONMENTAL SCIENCE FOR HUMAN LIFE PROFESSOR, 生活環境研究センター, 教授 (40017231)
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| Project Period (FY) |
1994 – 1995
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| Keywords | alpha-tocopherol / vitamin E / alpha-tocopherol stereoisomers / biodiscrimination / tissue concentration / all-rac-alpha-tocopherol / 2-ambo-alpha-tocopherol / RRR-alpha-tocopherol |
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| Research Abstract |
Among vitamin E analogs alpha-tocopherol has the highest biological activity. alpha-Tocopherol divides into natural and synthetic ones. The latter is called to all-rac-alpha-tocopherol and the equimolar mixture of eight stereoisomers. We studied the biological discrimination and distribution in tissues of stereoisomers of alpha-tocopherol in vivo after oral or intravenous administrarion of all-rac-alpha-tocopherol to rats. After administration of all-rac-alpha-tocopherol for 6 weeks, all of tissues tested in rats were rich in 2R stereoisomers with a small amounts of 2S isomers. But, by 24 hours after intarvenous administration of all-rac-alpha-tocopherol 2S isomers were predominant only in liver, whereas all tissues except liver 2R isomers were predominant. To know how to discriminate steroisomers of all-rac-alpha-tocopherol in body we tried the possibility of discrimination during absorption process using canulation methods into lymphatic duct and cultured Caco-2 cells as a model of absorption. These two methods showed that no discrimination occured during absorption. Theseresults indicate the possibility of biodiscrimination to be occured in liver during to excrete very low density lipoprotein into blood. Also, these results suggested the particication of alpha-tocopherol transfer protein (alpha-TTP) to be present only in liver. This alpha-TTP has the highest affinity with RRR-alpha-tocopherol among all of stereoisomers of alpha-tocopherol and other tocopherol analogs. Therefore, we concluded that this alpha-TTP was a key substance for biodiscrimination of vitamin E analogs and alpha-tocopherol stereoisomers.
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