Vitamin-A-alkohol Chemische Eigenschaften,Einsatz,Produktion Methoden
R-Sätze Betriebsanweisung:
R22:Gesundheitsschädlich beim Verschlucken.
R38:Reizt die Haut.
R67:Dämpfe können Schläfrigkeit und Benommenheit verursachen.
R65:Gesundheitsschädlich: kann beim Verschlucken Lungenschäden verursachen.
R62:Kann möglicherweise die Fortpflanzungsfähigkeit beeinträchtigen.
R51/53:Giftig für Wasserorganismen, kann in Gewässern längerfristig schädliche Wirkungen haben.
R48/20:Gesundheitsschädlich: Gefahr ernster Gesundheitsschäden bei längerer Exposition durch Einatmen.
R11:Leichtentzündlich.
S-Sätze Betriebsanweisung:
S36/37:Bei der Arbeit geeignete Schutzhandschuhe und Schutzkleidung tragen.
S61:Freisetzung in die Umwelt vermeiden. Besondere Anweisungen einholen/Sicherheitsdatenblatt zu Rate ziehen.
S62:Bei Verschlucken kein Erbrechen herbeiführen. Sofort ärztlichen Rat einholen und Verpackung oder dieses Etikett vorzeigen.
Beschreibung
Human vitamin A is derived from the natural food. Natural vitamin A exists in dif ferent forms. In animal tissues, vitamin A is present in the form of retinoids.
However, in plants, the form of vitamin A called carotenoids is contained in the
green, orange, and yellow plant tissue. Vitamin A compounds such as retinol, reti nal, carotene, and so on from these foods can be converted to vitamin A in the
human body. Therefore, food is the main source of vitamin A.
As early as 1000 years ago, the Qian Jin Yao Fang written by Sun Simiao in Tang
Dynasty recorded that animal liver can cure night blindness. This is the early
recognition in vitamin A supplementation. The traditional Chinese medicine books
also recorded that nourishing the liver can improve eyesight. Researches on the
therapy of vitamin A deficient-diseases are mainly related to nourishing the liver
and kidney, supplementing essence and blood, and activating qi
Chemische Eigenschaften
Yellow-Orange Powder
Physikalische Eigenschaften
Vitamin A1 (VA1), Molecular formula, C20H30O; MW, 286.45; CAS, 68-26-8.
Melting point: 62–64 °C. Boiling point: 137–138 °C
VA2, Molecular formula, C20H28O; MW, 284.44; Melting point: 17–19 °C.
History
The vitamin research is the great achievement in the development of life sciences,
while human beings only took half a century to discover and understand vitamins.
However, everything is still very difficult for scientists in the early stage of vitamin
discovery. From 1913 to 1915, Elmer McCollum and Marguerite Davis indicated
that the growth rate was maintained by at least two different kinds of growth factors:
one can be separated from eggs or butter, and the other one which multiple neuritis of chicks and pigeons can be extracted by water; thus they were
named fat-soluble vitamin A and water-soluble vitamin B.prevented
In 1919, the researchers demonstrated that fat-soluble vitamin A not only sup ported the rate of growth but also prevented eye dryness and night blindness in the
process of property study. In 1920, Dr. J.C. Drummond named this active lipid as
vitamin A. It exists in cod liver oil and prevents the occurrence of eye dryness and
night blindness.
Verwenden
Occurs preformed only in animals; metabolized from carotenoids, such β-carotene, in the intestinal mucosa. Dietary sources include liver, milk, butter, cheese, eggs and fish liver oils or as carotenoi
s from fruits and vegetables. Stored primarily in the liver in esterified form; transported in the blood by retinol binding protein (RBP). Nutritional factor.
Definition
ChEBI: A retinol in which all four exocyclic double bonds have E- (trans-) geometry.
Indications
Vitamin A, or retinol, is essential for the proper maintenance
of the functional and structural integrity of epithelial
cells, and it plays a major role in epithelial differentiation.
Bone development and growth in children
have also been linked to adequate vitamin A intake.
Vitamin A, when reduced to the aldehyde 11-cis-retinal,
combines with opsin to produce the visual pigment
rhodopsin. This pigment is present in the rods of the
retina and is partly responsible for the process of dark
adaptation.
Weltgesundheitsorganisation (WHO)
Vitamin A, a fat-soluble vitamin, is used in the treatment and
prevention of vitamin A deficiency resulting from inadequate dietary intake. It has
been demonstrated to be teratogenic at high doses (more than 25,000 IU per day).
Daily dosages of less than 10000 IU seem to be free of this risk. Retinol (vitamin A)
is listed in the WHO Model List of Essential Drugs.
Allgemeine Beschreibung
Retinal, retinol and retinoic acid are the aldehyde, alcohol and acid forms of vitamin A. The retinoids exist as many geometric isomers due to the unsaturated bonds in the aliphatic chain. Retinol is biologically active in a wide range of processes.
Clinical Use
Principal dietary sources of vitamin A are milk fat
(cheese and butter) and eggs. Since it is stored in the
liver, inclusion of liver in the diet also provides vitamin
A. A plant pigment, carotene, is a precursor for vitamin
A and is present in highly pigmented vegetables, such as
carrots, rutabaga, and red cabbage.
An early sign of hypovitaminosis A is night blindness.
This condition is related to the role of vitamin A as
the prosthetic group of the visual pigment rhodopsin.
The night blindness may progress to xerophthalmia
(dryness and ulceration of the cornea) and blindness.
Other symptoms of vitamin A deficiency include cessation
of growth and skin changes due to hyperkeratosis.
Since vitamin A is a fat-soluble vitamin, any disease
that results in fat malabsorption and impaired liver storage
brings with it the risk of vitamin A deficiency; these
conditions include biliary tract disease, pancreatic disease,
sprue, and hepatic cirrhosis. One group at great
risk are children from low-income families, who are
likely to lack fresh vegetables (carotene) and dairy
products (vitamin A) in the diet.
Nebenwirkungen
Acute hypervitaminosis A results in drowsiness,
headache, vomiting, papilledema, and a bulging fontanel
in infants. The symptoms of chronic toxicity include
scaly skin, hair loss, brittle nails, and hepatosplenomegaly.
Anorexia, irritability, and swelling of
the bones have been seen in children. Retardation of
growth also may occur. Liver toxicity has been associated
with excessive vitamin A intake. Vitamin A is teratogenic
in large amounts, and supplements should not
be given during a normal pregnancy. The IOM has reported
the UL of vitamin A to be 3,000 μg/day.
Sicherheitsprofil
Moderately toxic by
ingestion. Human teratogenic effects by
ingestion: developmental abnormalities of
the craniofacial area and urogenital system.
An experimental teratogen. Experimental
reproductive effects. Human mutation data
reported. When heated to decomposition it
emits acrid smoke and irritating fumes.
läuterung methode
Purify retinol by chromatography on columns of water-deactivated alumina and elute with 3-5% acetone in hexane. Separate the isomers by TLC plates on silica gel G, developed with pet ether (low boiling)/methyl heptanone (11:2). Store it in the dark, under N2, at 0o, or in Et2O, Me2CO or EtOAc. [See Gunghaly et al. Arch Biochem Biophys 38 75 1952, Beilstein 6 IV 4133.]
Vitamin-A-alkohol Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
