Its precursors are some carotenoids and retinyl esters
(palmitate, propionate, acetate) [2,3].
This study agrees with Lima (26) by showing that after vitamin A supplementation there is an increase in the transfer of retinyl esters
to the mammary gland in lactating women who have low retinol levels in the colostrum.
TRL-plasma concentrations of retinyl esters
increased in response to consumption of both biofortified cassava porridge and gari, and the VA equivalencies of beta-carotene in porridge and gari were estimated as ~4.4:1 and 4.2:1, respectively.
Hepatocytes are mainly involved in the uptake of retinyl esters
from chylomicrons, transfer of retinol to HSCs, and synthesis of retinol-binding protein (RBP) (1).
The diet provides retinol as retinyl esters
or as provitamin carotenoids, and majority of them are stored within the hepatic lipid droplets (Blaner et al., 1985).
Norum, "Retinol and retinyl esters
in parenchymal and nonparenchymal rat liver cell fractions after long-term administration of ethanol," Journal of Lipid Research, vol.
Interaction of Fatty Acid Binding Protein with Microsomes: Removal of Palmitic Acid and Retinyl Esters
. [[sup.14]C] palmitic acid or [3H] retinyl esters
incorporated in microsomal membranes were removed by a cytosolic fraction enriched in fatty acid binding protein.
Human epidermis contains endogenous retinoids (retinol and retinyl esters
) and carotenoids (mostly beta-carotene).
Retinoids allowed for use in cosmetic products include retinol and retinyl esters
(for example, retinyl palmitate).
In addition, the concentrations of retinyl esters
after ingestion of a fat-rich meal containing vitamin A have been used as markers of the presence of apo B-48-containing RLPs of intestinal origin.
Retinol, alpha-tocopherol, lutein/zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, trans-beta-carotene, and four retinyl esters
in serum determined simultaneously by reversed-phase HPLC with multi-wavelength detection.
This can lead to a buildup in the liver of compounds called retinyl esters
, which can be toxic in large amounts.