Effect of sesame seed on tocopherol metabolism in α-tocopherol transfer protein knock out mice

α-生育酚在8种维生素E亚型中具有最高的生物活性。它们以同样的方式被吸收并被带到肝脏。而肝细胞内α-生育酚转运蛋白（a-TTP）仅将α-生育酚转运至VLDL并转运至各组织。其他同型如g-生育酚被代谢为羧乙基羟色胺（CEHC）并排泄到尿中。因此，a-生育酚在人体和大鼠体内的组织和血液中的浓度高于其他同型异构体。维生素E同型体对a- ttp的亲和力是其生物活性的关键决定因素。Α-TTP敲除小鼠不能保留α-生育酚。另一方面，芝麻的木脂素抑制了生育酚对CEHC的代谢，产生较高的生育酚水平。在本研究中，我们检测了芝麻木脂素是否在α-TTP KO小鼠中产生更高的生育酚水平。芝麻及其木脂素没有引起体内较高的生育酚水平，尽管芝麻木脂素可以抑制CEHC的排泄。这些结果表明α-TTP对生育酚的保留是不可缺少的。

α-Tocopherol indicates the highest biological activity among 8 vitamin E isoforms. They are absorbed similarly and carried to the liver. However, α-tocopherol transfer protein (a-TTP) in liver cells carries only α-tocopherol to VLDL and transported to the various tissues. The other isoforms such as g-tocopherol are metabolized to carboxyethylhydroxycromans (CEHC) and excreted into urine. Therefore, the a-tocopherol concentrations in tissues and blood are greater than those of other isoforms in humans and rats. The affinity of vitamin E isoforms for a-TTP is a critical determinationant of their biological activities. Α-TTP knock out mice can not retain α-tocopherol. On the other hand, sesame seed its lignans inhibit tocopherol metabolism to CEHC and produce higher tocopherol levels. In the present study, we examined whether or not sesame lignans produced higher tocopherol levels in α-TTP KO mice. Sesame seed and its lignans did not induced higher tocopherol levels in the body, in spite of CEHC excretion was inhibited by sesame lignans. These results suggest α-TTP is indispensable on retention of tocopherol.