Antirachitic vitamins Vitamin

The steroids include a broad-spectrum of important compounds which exhibit remarkable pharmacodynamic properties, namely adrenal cortical hormones, sex hormones, cardiac glycosides, antirachitic vitamins (Vitamin D), toad poisons, saponins, bile acids and some alkaloids. 

Antirachitic vitamin Antiredeposition agents Antirust additives Antiscaling additives Antiscorbutic vitamin Antiseize material Antisense agents Antisense DNA... 

The vitamin and metabolic derivatives of a fat-soluble substance calciferol. These antirachitic vitamins are produced from A -unsaturated sterols upon irradiation with ultraviolet light. Population biologists have adduced strong evidence for the hypothesis that lighter skin color, the primary characteristic of race, is related to the lower solar radiance in northern climes. Vitamin D plays a central role in calcium metabolism, both in terms of... 

On the positive side, there are photochemical reactions that are essential for human health. One of these is the formation of vitamin D (the antirachitic vitamin) by irradiation of ergosterol. This photochemical reaction is an electro-cyclic ring opening of the cyclohexadiene ring of ergosterol of the type described in Section 28-2D. The product, previtamin D2, subsequently rearranges thermally to vitamin D2 ... 

Flydroxvlation yields VITD-R agonist 1,25-Dihvdroxyvitamin D3 [antirachitic] Vitamin D deficiency causes rickets — shown by Elmer McCollum... 

Use Antirachitic vitamin when irradiated with UV light, it has vitamin D activity source of estradiol. 

Toxicology LD50 (oral, rat) 42 mg/kg poison by ingestion experimental teratogen TSCA listed Precaution Affected by air and light Hazardous Decomp. Prods. Heated to decomp., emits acrid smoke and irritating fumes Uses Rodenticide dietary supplement nutrient animal feed additive pharmaceutical ingred. medicine (antirachitic vitamin) mfg. of human and veterinary specialties for oral and parenteral use... 

Phenylhydrazine antiquing, metal Antimony pentasulfide antirachitic vitamin, pharmaceuticals Cholecalciferol antirachitic, pharmaceuticals Ergocalciferol antiredeposition agent Maleic acid/olefin copolymer, sodium salt Sodium polyacrylate antiredeposition agent, dry cleaning Butylated PVP... 

Because of the possibility of its biosynthesis in the body and its biological function (it is an antirachitic vitamin connected with the metabolism of calcium and phosphorus, which are necessary for growth, development and maintenance of bone structure), some reports state that vitamin Dj is more a hormone than a vitamin. 

The discovery of vitamin D as the antirachitic vitamin and the recognition of fish-liver oils as a potent source led to the advice that babies should receive cod-liver oil or some concentrate of vitamin D. Prevention of rickets and development of strong bones in young children depend on an adequate intake of calcium and phosphorus, as well as vitamin D, and therefore fortification of milk with vitamin D was begun in the early 1930s. The Council on Foods and Nutrition of the American Medical Association approved the fortification of milk. 

The letter D was used to designate the antirachitic vitamin of liver oil (for its physiological action see Chapt. XXII-4). Windaus first prepared vitamin D by irradiating ergosterol and determined its constitution. 

Uses Rodenticide dietary supplement nutrient animal feed additive pharmaceuticals ingred. medicine (antirachitic vitamin) mfg. of human and veterinary specialties for oral and parenteral use... 

The observation that the uv spectmm of provitamin D changed with uv inradiation and also produced antirachitic activity led to the conclusion that vitamin D was derived from the provitamin. Windaus found the vitamin D2 formula to be isomeric with the provitamins. 

Irradiated ergosterol was found not to be as antirachitic in the chick as in the rat, whereas the chick could be protected by direct kradiation. The provitamin in cholesterol was shown not to be ergosterol. Rygh (14) in 1935 found that 1 rat unit of cod Hver oil was 100 times more potent in chicks than 1 rat unit of vitamin D2. Brockmann (15) in 1936, prepared the pure crystalline 3,5-dinitrobenzoate derivative of vitamin D obtained from tuna Hver oil... 

Ergosterol occurs in plants and yeast and is important as a precursor of vitamin D (Figure 14—18). When irradiated with ultraviolet Hght, it acquires antirachitic properties consequent to the opening of ring B. 

In 1918, Mellanby produced experimental rickets in dogs. In 1919, Huldschinsky ameliorated rachitic symptoms in children with ultraviolet radiation. Hess, in 1922, showed that liver oils contain the same antirachitic factor as sunlight In that same year, McCollum increased calcium deposition in rachitic rats with cod liver oil factor. In 1924. Steenbook and Hess demonstrated irradiated foods have antirachitic properties, It was in 1925 that McCollum named antirachitic factor as vitamin D. In 1931, Angus isolated crystalline vitamin D (calciferol). In 1936, Windaus isolated vitamin D3 (activated 7-dehydrocholesterol). 

The stability of vitamin D in fats and oils corresponds to the stability of the fat itself, as described previously for vitamin A. Vitamin D is, however, more stable than vitamin A under comparable conditions. Once freed from the protection of the food matrix, vitamin D is susceptible to decomposition by oxygen and light. The vitamin is stable towards alkali, but under conditions of even mild acidity the molecule isomerizes to form the 5,6-trans and isotachysterol isomers, neither of which possesses any significant antirachitic activity (42). 

The chicken egg yolk, as deduced from its antirachitic activity, contains 1-2 pg of cholecal-ciferol and this can be raised further by increasing the intake of vitamin D3 of the laying hen (94). The concentration in yolk is 5-10 times higher than that of total vitamin D3 plus its metabolites in blood plasma of normal chickens and 50-100 times higher than the concentration in any other tissue (95). Consequently, the chicken egg yolk is a potent source of vitamin D3. 

Because several of the metabolites of vitamin D3 are biologically active, the molecular species of vitamin D3 which passes into the yolk cannot be determined just from measurement of antirachitic activity. Consequently, a reliable and sensitive method for determining the amount of the unchanged form of vitamin D3 would be extremely beneficial to those interested in the metabolism and other factors that influence the chicken to deposit vitamin D3 in... 

Vitamin D has been known for more than half a century to be a powerful antirachitic agent, necessary for the development of normal bone. However, and oddly enough, its primary and most direct effect in this tissue is the stimulation of bone resorption [36] leading to an increase in the circulating levels of calcium and phos-... 

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