Kiyose C, Muramatsu R, Fujiyama-Fujiwara Y, Ueda T, Igarashi O
Institute of Environmental Science for Human Life, Ochanomizu University, Tokyo, Japan.
Lipids. 1995 Nov;30(11):1015-8. doi: 10.1007/BF02536286.
Synthetic alpha-tocopherol (alpha-Toc) contains equal amounts of eight different stereoisomers, and the four stereoisomers with the 2R configuration are generally more active than their corresponding 2S-isomers. We investigated the biodiscrimination of alpha-Toc stereoisomers during intestinal absorption in situ and in vitro. Intestinal absorption of alpha-Toc stereoisomers was examined in situ in vitamin E-deficient rats with cannulated thoracic ducts. We found that the ratios of alpha-Toc stereoisomers in lymph of the all-rac-alpha-Toc group were the same as the administered alpha-Toc stereoisomers, and 2R-isomers occupied approximately 50% of absorbed alpha-Toc. The uptake of alpha-Toc stereoisomers also was measured using Caco-2 cells cultured on filter membranes. The concentration of RRR-alpha-Toc in Caco-2 cells was not significantly different from that of SRR-alpha-Toc. Therefore, the discrimination of alpha-Toc stereoisomers does not occur during absorption in small intestine, suggesting the liver as source for the biodiscrimination.
合成α-生育酚（α-Toc）含有等量的八种不同立体异构体，且具有2R构型的四种立体异构体通常比其相应的2S异构体活性更高。我们研究了α-Toc立体异构体在原位和体外肠道吸收过程中的生物辨别情况。在具有胸导管插管的维生素E缺乏大鼠中，原位检测α-Toc立体异构体的肠道吸收情况。我们发现，全消旋α-Toc组淋巴中α-Toc立体异构体的比例与所给予的α-Toc立体异构体相同，且2R异构体约占吸收的α-Toc的50%。还使用在滤膜上培养的Caco-2细胞测量了α-Toc立体异构体的摄取情况。Caco-2细胞中RRR-α-Toc的浓度与SRR-α-Toc的浓度无显著差异。因此，在小肠吸收过程中不会发生α-Toc立体异构体的辨别，提示肝脏是生物辨别的来源。
