Alltransretinyl

Alltransretinyl is a chemical compound belonging to the retinoid family of vitamin A derivatives. Its systematic name is (3E,5E,7E,9E,11E,13E,15E,17E,19E)-3,17,19-trihydroxytetracosa-3,5,7,9,11,13,15,17,19-nonaene, but it is more commonly referred to as all-trans retinyl ester or all-trans retinol ester. The molecule consists of a long hydrocarbon chain derived from vitamin A (retinol) that has undergone esterification, typically at one of the terminal hydroxyl groups. The trans (E) configuration across each double bond in the unsaturated chain distinguishes it from cis isomers and contributes to its biological activity.

Alltransretinyl is naturally present in many animal tissues, where it serves as a storage form of vitamin A. In the retina of vertebrate eyes, the ester is accumulated in the rod outer segment disc membranes, acting as a reservoir that can be hydrolyzed to free all-trans retinol and eventually to retinaldehyde. This pathway is essential for the visual cycle and the regeneration of 11‑cis‑retinal, the chromophore that binds to opsins to form visual pigments. The ester can also be found in the liver, adipose tissue, and other organs where vitamin A metabolism is active.

The metabolism of alltransretinyl involves lipase-mediated de‑esterification, producing all‑trans retinol that can be oxidized to retinaldehyde and further to retinoic acid. Retinoic acid, in turn, acts as a transcriptional regulator of gene expression by binding retinoic acid receptors. Disruption of alltransretinyl synthesis or catabolism can lead to visual disorders such as night blindness or retinal dystrophies.

Synthetic alltransretinyl is produced via chemical esterification of retinol with fatty acids, often employing acid catalysts or enzymatic methods. It is used in research to study retinoid metabolism, in pharmacology to investigate visual cycle modulators, and in veterinary medicine as a supplement for animals with vitamin A deficiency.