α-Tocomonoenol Is Bioavailable in Mice and May Partly Be Regulated by the Function of the Hepatic α-Tocopherol Transfer Protein

Tocomonoenols are vitamin E derivatives present in foods with a single double bond at carbon 11’ in the sidechain. The α-tocopherol transfer protein (TTP) is required for the maintenance of normal α-tocopherol (αT) concentrations. Its role in the tissue distribution of α-11′-tocomonoenol (αT(1)) is unknown. We investigated the tissue distribution of αT(1) and αT in wild-type (TTP(+/+)) and TTP knockout (TTP(−/−)) mice fed diets with either αT or αT(1) for two weeks. αT(1) was only found in blood, not tissues. αT concentrations in TTP(+/+) mice were in the order of adipose tissue > brain > heart > spleen > lungs > kidneys > small intestine > liver. Loss of TTP function depleted αT in all tissues. αT(1), contrary to αT, was still present in the blood of TTP(−/−) mice (16% of αT(1) in TTP(+/+)). Autoclaving and storage at room temperature reduced αT and αT(1) in experimental diets. In conclusion, αT(1) is bioavailable, reaches the blood in mice, and may not entirely depend on TTP function for secretion into the systemic circulation. However, due to instability of the test compounds in the experimental diets, further in vivo experiments are required to clarify the role of TTP in αT(1) secretion. Future research should consider compound stability during autoclaving of rodent feed.