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

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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.