T3D2699

2741 T3D2699

Vitamin A

Vitamin A (retinol) is a yellow fat-soluble, antioxidant vitamin important in vision and bone growth. It belongs to the family of chemical compounds known as retinoids. Retinol is ingested in a precursor form; animal sources (milk and eggs) contain retinyl esters, whereas plants (carrots, spinach) contain pro-vitamin A carotenoids. Hydrolysis of retinyl esters results in retinol while pro-vitamin A carotenoids can be cleaved to produce retinal. Retinal, also known as retinaldehyde, can be reversibly reduced to produce retinol or it can be irreversibly oxidized to produce retinoic acid. Retinol and derivatives of retinol that play an essential role in metabolic functioning of the retina, the growth of and differentiation of epithelial tissue, the growth of bone, reproduction, and the immune response. Dietary vitamin A is derived from a variety of carotenoids found in plants. It is enriched in the liver, egg yolks, and the fat component of dairy products. 68-26-8

445354

C20H30O

286.229670 White powder.

63.5°C

0.671 mg/L

Oral, readily absorbed from the normal gastrointestinal tract

Vision:Vitamin A (all-trans retinol) is converted in the retina to the 11-cis-isomer of retinaldehyde or 11-cis-retinal. 11-cis-retinal functions in the retina in the transduction of light into the neural signals necessary for vision. 11-cis-retinal, while attached to opsin in rhodopsin is isomerized to all-trans-retinal by light. This is the event that triggers the nerve impulse to the brain which allows for the perception of light. All-trans-retinal is then released from opsin and reduced to all-trans-retinol. All-trans-retinol is isomerized to 11-cis-retinol in the dark, and then oxidized to 11-cis-retinal. 11-cis-retinal recombines with opsin to re-form rhodopsin. Night blindness or defective vision at low illumination results from a failure to re-synthesize 11-cis retinal rapidly. Epithelial differentiation: The role of Vitamin A in epithelial differentiation, as well as in other physiological processes, involves the binding of Vitamin A to two families of nuclear retinoid receptors (retinoic acid receptors, RARs; and retinoid-X receptors, RXRs). These receptors function as ligand-activated transcription factors that modulate gene transcription. When there is not enough Vitamin A to bind these receptors, natural cell differentiation and growth are interrupted.

Hepatic. Retinol is conjugated with glucuronic acid; the B-glucuronide undergoes enterohepatic circulation and oxidation to retinol and retinoic acid. Retinoic acid undergoes decarboxylation and conjugation with glucuronic acid. Half Life: 1.9 hours No indication of carcinogenicity to humans (not listed by IARC).

For the treatment of vitamin A deficiency. Vitamin A helps regulate the immune system, which helps prevent or fight off infections by making white blood cells that destroy harmful bacteria and viruses.

Acute toxicity (single ingestion of 7 500 RE or 25 000 IU per kg or more): Signs and symptoms may be delayed for 8 to 24 hours and include: increased intracranial pressure, headache, irritability, drowsiness, dizziness, lethargy, vomiting, diarrhea, bulging of fontanels in infants, diplopia, papilledema. Peeling of skin around mouth may be observed from 1 to several days after ingestion and may spread to the rest of the body. The treatment of hypervitaminosis A consists of immediate withdrawal of the vitamin along with symptomatic and supportive treatment. (L1712)

2009-07-21T20:26:11Z

2014-12-24T20:25:49Z

Vitamin_A

C00473

100640 103730 107740 115300 120930 124020 136880 146732 151675 155050 164320 175100 176300 176803 176870 180069 180090 180100 180230 180245 180250 180260 180280 180290 180380 222448 240150 277350 300008 300009 300102 308990 600073 600086 600281 600463 600768 601186 601617 601691 602630 603687 604232 604863 605072 606467 606530 606623 606990 607599 607849 608575 608604 608830 608989 610745 611474 611589 611596

17336

RETINOL

Vitamin A

DB00162

RTL

3068

true

[H]\C(CO)=C(\C)/C(/[H])=C(\[H])/C(/[H])=C(\C)/C(/[H])=C(\[H])C1=C(C)CCCC1(C)C

C20H30O

InChI=1S/C20H30O/c1-16(8-6-9-17(2)13-15-21)11-12-19-18(3)10-7-14-20(19,4)5/h6,8-9,11-13,21H,7,10,14-15H2,1-5H3/b9-6+,12-11+,16-8+,17-13+

InChIKey=FPIPGXGPPPQFEQ-OVSJKPMPSA-N

286.4516

286.229665582

Endogenous Solid 5.68

HMDB00305

CHEMBL986

393012

William Oroshnik, “Synthesis of Vitamin A, intermediates and conversion thereof to Vitamin A.” U.S. Patent US4092366, issued May, 1948.