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

Abstract

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 (αT1) is unknown. We investigated the tissue distribution of αT1 and αT in wild-type (TTP+/+) and TTP knockout (TTP−/−) mice fed diets with either αT or αT1 for two weeks. αT1 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. αT1, contrary to αT, was still present in the blood of TTP−/− mice (16% of αT1 in TTP+/+). Autoclaving and storage at room temperature reduced αT and αT1 in experimental diets. In conclusion, αT1 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 αT1 secretion. Future research should consider compound stability during autoclaving of rodent feed.

Metabolism of 11′‐α‐ and 11′‐γ‐Tocomonoenols in HepG2 Cells Favors the γ‐Congener and Results Predominantly in Carboxymethylbutyl‐Hydroxychromans

“…[ 21,34 ] The observed differences in the extent of metabolism of T3 and T1 suggest that the degree of saturation and/or the position of double bonds in the sidechain may influence the affinity of tocochromanols for their metabolizing enzymes. These data might partially explain the bioavailability of T1 congeners observed in rodents [ 20,24 ] and humans. [ 25 ]…”

“…[19] Feeding studies suggest bioavailability of 𝛾T1 in mice. [20] 11′-𝛼-Tocomonoenol (𝛼T1) is present in vegetable oils [5,[16][17][18] and microalgae, [11][12][13] and it is bioavailable in mice [20,24] and humans. [25] Its uptake and metabolism in cultured liver cells is more similar to 𝛼T than 𝛼T3, suggesting the possibility that, due to structural similarities, it may share some biological functions with 𝛼T.…”

Countercurrent chromatography isolation of 11′‐γ‐tocomonoenol from pumpkin seed oil with detection of novel minor tocochromanols

“…Admittedly, the expenditure (44 saponifications, 11 CCC runs, $45 column chromatographic separations) was high, but a scale up of the employed methodology could produce larger quantities of γ-T1 which could be used for studies of its biological activity. Recently, α-T1 was found to behave differently to both α-T and α-T3 (Irías-Mata et al, 2020). For example, it does not seem to entirely depend on α-tocopherol transfer protein (TTP) function for its secretion into the systemic circulation (Irías-Mata et al, 2020).…”

“…Recently, α-T1 was found to behave differently to both α-T and α-T3 (Irías-Mata et al, 2020). For example, it does not seem to entirely depend on α-tocopherol transfer protein (TTP) function for its secretion into the systemic circulation (Irías-Mata et al, 2020). Similar studies with γ-T1 would ultimately support the understanding of minor tocochromanols.…”

Countercurrent chromatographic isolation of 11´-γ-tocomonoenol from and detection of novel minor tocochromanols in pumpkin seed oil

“…CCC fractions with highest purities of γ-T1 according to GC/MS analysis (generally CCC fractions [16][17][18][19], partly also CCC fractions 15 and 20 and scarcely CCC fractions 14 and 21) were further purified by column chromatography (1 cm inner diameter glass column filled with 5 g silica gel 60, deactivated with 20% water) according to Hammann et al (2015). The selection criterion was a maximum of 5% interfering β-/γ-tocochromanols in relation to γ-T1 in the fraction.…”