Intestinal Epithelial Cells Absorb γ‐Tocotrienol Faster than α‐Tocopherol

Abstract

To elucidate the transepithelial transport characteristics of lipophilic compounds, the cellular uptake of tocopherol and tocotrienol isomers were investigated in Caco2 cell monolayer models. These vitamin E isomers formed mixed micelles consisting of bile salts, lysophospholipids, free fatty acid, and 2-monoacylglycerols, then the micelles were supplied to Caco2 cells. The initial accumulation of tocotrienol isomers in Caco2 cells was larger than those of corresponding tocopherol isomers. There was little difference among the cellular accumulations of four tocopherol isomers. These findings suggested that the difference between the molecular structures of the C16 hydrocarbon chain tail in tocopherol and tocotrienol was strongly responsible for the rapid epithelial transport into the Caco2 cells membranes rather than the difference in the molecular structures of their chromanol head groups. Furthermore, the secretion of alpha-tocopherol and gamma-tocotrienol from Caco2 cells was investigated using Caco2 cells plated on a transwell. The time courses of their secretions from Caco2 cells showed that the initial secretion rate of gamma-tocotrienol was also larger than that of alpha-tocopherol. To investigate the intestinal uptake of alpha-tocopherol and gamma-tocotrienol in vivo, the mice were fed single doses of alpha-tocopherol or gamma-tocotrienol with triolein. The gamma-tocotrienol responded faster in plasma than alpha-tocopherol, although the maximal level of gamma-tocotrienol was lower than that of alpha-tocopherol. This suggested that the intestinal uptake properties of administered alpha-tocopherol and gamma-tocotrienol would characterize their plasma level transitions in mice.

Use of recovered frying oils in chicken and rabbit feeds: effect on the fatty acid and tocol composition and on the oxidation levels of meat, liver and plasma

“…Tocotrienols are absorbed by intestinal cells faster than tocopherols (Tsuzuki et al, 2007). However, in liver, aT is preferentially carried stereo-selectively by the cytosolic aT transfer protein to very-low-density lipoproteins and then released into the circulation (Schneider, 2005).…”

Mechanisms for the prevention of vitamin E excess

“…Thus, the low ␥ -tocopherol and high ␣ -tocopherol concentrations did not lead to discrimination between the tocopherols, suggesting that solubility in the intestinal lumen, rather than concentration, is critical for absorption. Indeed, based on their greater fl uidity, there may be preference for uptake of tocotrienols into the enterocyte, but following absorption, there is rapid metabolism of the non-␣ -tocopherol forms (45)(46)(47)(48), which is discussed further below.…”

Use of palm-oil by-products in chicken and rabbit feeds: effect on the fatty acid and tocol composition of meat, liver and plasma

“…Intestinal cells absorb tocotrienols faster than tocopherols, and then both tocopherols and tocotrienols are transported in chylomicrons from the intestine and subsequently to the liver in remnants (Tsuzuki et al, 2007). There, aT is preferentially carried stereo-selectively by the cytosolic protein aT transfer protein (aTTP) to a very low-density lipoprotein and then it is released into the circulation (Schneider, 2005).…”