Alcohol vitamin A and

Leo MA, Lieber CS. Alcohol, vitamin A, and beta-carotene adverse interactions, including hepatotoxicity and carcinogenicity. Am J Clin Nutr 1999 69(6) 1071-85. 

The first example is the plasma-borne retinol-binding protein, RBP, which is a single polypeptide chain of 182 amino acid residues. This protein is responsible for transporting the lipid alcohol vitamin A (retinol) from its storage site in the liver to the various vitamin-A-dependent tissues. It is a disposable package in the sense that each RBP molecule transports only a single retinol molecule and is then degraded. 

Susceptibility to lead toxicity is influenced by dietary levels of calcium, iron, phosphorus, vitamins A and D, dietary protein, and alcohol (Calabrese 1978). Low dietary ingestion of calcium or iron increased the predisposition to lead toxicity in animals (Barton et al. 1978a Carpenter 1982 Hashmi et al. 1989a Six and Goyer 1972 Waxman and Rabinowitz 1966). Iron deficiency combined with lead exposure acts synergistically to impair heme synthesis and cell metabolism (Waxman and Rabinowitz 1966). 

Suitably positioned vinyl halide can undergo Heck-type intramolecular coupling to generate dienes (equations 124 and 125)216,217. When one of the reacting partners in the Heck reaction is a diene, trienes are obtained (equation 126)218. Heck coupling of ally lie alcohols and alkenyl iodides has been employed for the synthesis of vitamin A and related compounds (equation 127)219,220. A similar double Heck reaction on a Cio-diiodide with a Cis-allylic alcohol leads to -carotene as a mixture of isomers (equation 128)209e. 

Another fat-soluble vitamin, E, was found by Evans and Bishop in 1923. Pregnant rats on a defined diet (alcohol-extracted casein, cornstarch, and lard) supplemented with butter (vitamins A and D) and yeast extract (vitamin B group) produced few young because of fetal resorption. Male rats on the same diet were sterile. The disorders, which have not been identified in man, were corrected by wheat-germ oil, from which tocopherol, the active ingredient, was isolated in 1936. In spite of intensive investigations and a recognition that the vitamin is an antioxidant and destroyer of free radicals, the function of vitamin E remains obscure. 

When utilization tests were run on a group of 18 male and 7 female human subjects, wide variations in blood level responses were found, particularly among the males.36 [Both in animals (rats) and humans the two sexes respond somewhat differently.] When 134,000 ig. of vitamin A in four different forms, viz., vitamin A alcohol, vitamin A acetate, vitamin A natural ester No. 1, and vitamin A natural ester No. 2, was fed to the group of 18 males on four different occasions, the serum levels found after 6 hours ranged from 178 to 1423 ig. per 100 ml., 122 to 1170 ig. per 100 ml., 110 to 1183 ig. per 100 ml., and 114 to 1230 ig. per 100 ml., respectively. These nearly 10-fold variations in serum levels do not, of course, indicate 10-fold variation in need, but they do show that the vitamin when given in relatively large doses does behave very differently in different individuals. 

This reaction based on the petrochemical crude material isobutylene makes the synthetic route to P-ionone (36) substantially shorter and cheaper, especially since the isomeric double bond proves to be advantageous in the subsequent reactions. In addition, i-methylheptenone (37 a) can be converted into methylheptenone (37) by noble metal-catalyzed isomerization. The reaction steps ethynylation (C2 addition), Carroll reaction (C3 addition), ethynylation and partial hydrogenation (C2 addition) lead from methylheptenone (37) via dehydrolinalool (42), pseudoionone (43) and p-ionone (36) to the C15 alcohol p-vinylionol (44). With triphenylphosphine (15), the desired C15 phosphonium salt (13), which is the second important synthetic building block for vitamin A and carotenoids16), is obtained directly from p-vinylionol, by allyl rearrangement. 

RetinalS. The structure and photophysics of rhodopsins are intimately related to the spectroscopic properties of their retiny1-polyene chromophore in its protein-free forms, such as the aldehyde (retinal), the alcohol (retinol or vitamin A), and the corresponding Schiff bases. Since most of the available spectroscopic information refers to retinal isomers (48-55), we shall first center the discussion on the aldehyde derivatives. Three bands, a main one (I) around 380 nm and two weaker transitions at 280 nm and 250 nm (II and III), dominate the spectrum of retinals in the visible and near ultraviolet (Fig. 2). Assignments of these transitions are commonly made in terms of the lowest tt, tt excited states of linear polyenes, the spectroscopic theories of which have been extensively discussed in the past decade (56-60). In terms of the idealized C2h point group of, for example, all-trans butadiene, transitions are expected from the Ta ground state to B , A, and A" excited states... 

ALCOHOL BETA-CAROTENE (a precursor to vitamin A and a popular antioxidant supplement) t risk of liver damage Alcohol combined with beta-carotene led to more liver damage than was produced by alcohol exposure alone Be aware... 

More commonly, waxes are esters of an alcohol other than glycerol (long chain alcohol, sterol, hydroxycarotenoids, vitamin A) and a long chain acid (wax esters). Wax esters are saponified by hot alkaline solutions and give a fatty acid and an alcohol. They are soluble in aromatic solvents, chloroform, ethers, esters and ketones. 

A minority of alcoholics develop nutrient deficiencies. In Western countries, alcoholics represcrit the largest population segment that can benefit from dietary intervention. Alcoholics are at risk for deficiencies in folate, thiamin, riboflavin, vitamin B, vitamin A, and magnesium, particularly when the intake of these substances is low. In some cases, absorption of the nutrient is impaired in others, catabolism of the nutrient is iitcreased. Thiamin deficiency is a firmly established consequence of alcoholism, as discussed in the iTiiamin section. 

Alcohol may also act indirectly by causing liver disease, which in turn can affect the capacity of the liver to export vitamin A, thereby enhancing its local toxicity. In alco-hoUcs the carrying capacity of retinol binding protein was increased, even in those with low serum retinol concentrations (97). In such cases, caution in the amount of vitamin A used for therapy is recommended. Similarly, diets that are severely deficient in protein can affect the capacity of the liver to export vitamin A and enhance its hepatotoxicity. 

Heck reaction is a diene, trienes are obtained (equation l26). Heck coupling of allylic alcohols and alkenyl iodides has been employed for the synthesis of vitamin A and related compounds (equation A similar double Heck reaction on a Cio-diiodide with... 

Very many chemicals are recognized teratogens in animals a significantly smaller subset of these is known or suspected to be developmental neurotoxicants in humans. Some of the more significant of the latter group include ethanol, which causes a constellation of effects ranging from fetal alcohol syndrome to alcohol-related neurodevelopmental disorder maternal smoking of tobacco (fetal tobacco syndrome) excess vitamins A and D heavy metals, particularly... 

A group at the Glaxo Laboratories found the reaction applicable to propargylic alcohols and used it in a synthesis of vitamin A, and further examples were explored by E. R. H. Jones and co-workers. Phenylpropiolic acid (1) is reduced first to phenylpropargyl alcohol, and this affords a complex which on decomposition with... 

Chronic overdrinking or binge-drinking alcoholism causes deficiencies of folate, thiamine, pyridoxine, vitamin A, and zinc, the combination of which causes multiple risks for disease, but mostly for cancer. 

Yellow prisms from propylene oxide or petr ether. Solvated crystals from more polar solvents, such as methanol or ethyl formate, mp 62-64°. Distills at 120-125" at 5 x lO-3 mm pressure, nj 1.6410 (calculated from refractive indexes of 20-70% solas in mineral oil), uv max 324-325 nm (E 1835) Baxter, Robeson, J. Am. Chem. Soc. 64, 2407 (1942+ Practically insol in water or glycerol sol in abs alcohol, methanol, chloroform, ether, fats and oils. Ultraviolet light inactivates vitamin A and its solns which exhibit a characteristic green fluorescence. The free alcohol is sensitive to air-oxidation, but oil solns of it are quite stable. Esters of vitamin A are more stable to oxidation. LDn (10 day) in mice (mg/kg) 1510 i.p. 2570 orally (Kamm). 

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