Mechanism of enhancing vitamin E activity by sesame seed or its lignans

通过两个实验研究了芝麻及其木脂素增强维生素E活性的机制。在实验1中，我们研究了摄入芝麻是否会抑制γ -生育酚（Toc）分泌到胆汁中。众所周知，人类和大鼠的血浆和肝脏中α -生育酚的含量远高于γ -生育酚。因此，假设不能与α - toc转移蛋白结合的γ - toc被排泄到胆汁中。然而，在之前的实验中，我们观察到，在相同的γ - toc摄入量下，喂食含有芝麻的饮食的大鼠血浆和肝脏中的γ - toc含量高于喂食含有γ - toc的饮食的大鼠。我们假设芝麻抑制了γ - toc排泄到胆汁中，所以我们测定了血浆、肝脏和胆汁中的γ - toc含量。我们意外地发现，当γ - toc在肝脏中的浓度高时，更多的γ - toc排泄到胆汁中，而当其在肝脏中的浓度低时，较少的γ - toc排泄到胆汁中。肝脏和胆汁中的γ - toc浓度非常低，表明γ - toc被迅速破坏，芝麻可能抑制γ - toc的破坏。在实验2中，我们检测了芝麻胺是否增强了生育酚的吸附。大鼠被分为三组。第1组饲喂20 mg生育酚与生育三烯醇混合物（Tmix），第2组饲喂20 mg生育三烯醇混合物（Tmix）和0.1%芝麻醇混合物（Tmix），第3组饲喂40 mg生育三烯醇混合物或每隔一天与0.2%芝麻醇混合物交替饲喂，不添加Tmix。组1表现为维生素E缺乏，组2和组3表现为维生素E水平显著改善。第2组和第3组对维生素E活性的增强作用基本相同。这些结果表明芝麻胺没有引起生育酚的吸收增强。

Mechanisms enhancing vitamin E activity by sesame seed or its lignans were investigated in two experiments.In experiment 1 we examined whether or not the excretion of gamma-tocopherol (Toc) into the bile is suppressed by sesame seed intake, It has been well known that alpha-Toc content is much higher than gamma-toc in the plasma and liver of humans and rats. It has thus been assumed that gamma-Toc, which cannot bind with the alpha-Toc transfer protein is excreted into the bile. However, in a previous experiment, we observed that gamma-Toc content in the plasma and liver was higher in rats fed a sesame seed containing diet than in a gamma-Toc diet with the same gamma-Toc intake. We supposed that sesame seed suppresses gamma-Toc excretion into the bile, so we determined the gamma-Toc contents in the plasma, liver and bile. We found unexpectedly that more gamma-Toc was excreted into the bile when its concentration in the liver was high, and that less gamma-Toc was excreted when its concentration in the liver was low. The very low gamma-Toc concentrations in the liver and bile suggest that gamma-Toc was destroyed very quiclky and the sesame seed may suppress gamma-Toc destruction.In experiment 2 we examined whether or not sesaminol enhanced tocopherol adsorption. Rats were divided into three groups. Group 1 received a diet contatining 20 mg of tocopherol and tocotrienol mixture (Tmix), group 2 received a diet containing 20 mg Tmix with 0.1% sesaminol, and group 3 received either a diet containing 40 mg Tmix or the same diet alternating with 0.2% sesaminol diet without Tmix every other day. Group 1 showed vitamin E deficient status but group 2 and 3 showed significant improvement of vitamin E status. The enhancing effects of vitamin E activities in group 2 and 3 were nearly the same. These results indicated that sesaminol did not cause an enhanced absorption of tocopherol.