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Chemical Properties
Vitamin B1 has an odor slightly reminiscent of thiazole and a bitter taste. When exposed to air, the vitamin rapidly
absorbs about 4% of water.
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Chemical Properties
White or almost white, crystalline powder or colourless crystals.
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Occurrence
Rice husks are reportedly the principal source of vitamin B1; in variable amounts it is a constituent of yeast,
milk, green leaves, roots and tubers; it is also present in high concentration in seeds, and in lesser amount in different animal organs
and muscles.
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Uses
A cofactor required for oxidation of carbohydrates and for the synthesis of ribose.
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Uses
Thiamine is a essential nutrient required for carbohydrate metabolism; also involved in nerve function. Biosynthesized by microorganisms and plants. Dietary sources include whole grains, meat products
, vegetables, milk, legumes and fruit. Also present in rice husks and yeast. Converted in vivo to Thiamine diphosphate, a coenzyme in the decarboxylation of α-keto acids. Chronic deficiency may lead t
o neurological impairment, bariberi, Wernicke-Korsakoff syndrome.
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Uses
Thiamine is the water-soluble vitamin b1, required for normal digestion and functioning of nerve tissues and in the prevention of beriberi. It also acts as a coenzyme in the metabolism of carbohydrates. During processing, the higher and longer the heating period, the greater the loss. The loss is reduced in the presence of acid. Thiamine hydrochloride and thiamine mononitrate are two available forms. The mononitrate form is less hygroscopic and more stable than the hydrochloride form, making it suitable for use in beverage powders. It is used in enriched flour and is found as thiamine mononitrite in frozen egg substitute and crackers.
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Preparation
By linking the preformed thiazole and pyrimidine ring system.
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Definition
ChEBI: A hydrochloride obtained by combining thiamine chloride with one molar equivalent of hydrochloric acid.
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General Description
Thiamine is a water-soluble vitamin of the B complex whose phosphate derivatives are involved in many cellular processes required for overall human health. Thiamine deficiency, often the result of impaired nutritional status associated with chronic diseases from alcoholism to HIV-AIDS, is monitored in patient whole blood samples by HPLC.
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Health Hazard
Diseases and disorders resulting from a deficiency of thiamine include beriberi, opisthotonos (in birds), polyneuritis, hyperesthesia, bradycardia, and edema. Rather than a specific disease, beriberi may be described as a clinical state resulting from a thiamine deficiency. In body cells, thiamine pyrophosphate is required for removing carbon dioxide from various substances, including pyruvic acid.
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Biochem/physiol Actions
Thiamine is an essential coenzyme in carbohydrate metabolism. Deficiency of thiamine causes beriberi, a neurological and cardiovascular disease. Thiamine is administered in case of deficiency, either due to reduced intake or synthesis. Congenital defect in the thiamine transporter gene SLC19A2 causes thiamine-responsive megaloblastic anemia syndrome (TRMA). Thiamine mimics acetylcholine in brain and possible exerts a role in Alzheimer′s disease. Thiamine deficiency in ruminants causes polioencephalomalacia.
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Environmental Fate
Thiamine and its common phosphate analogs are readily
soluble in water and ubiquitously utilized in nature.
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Purification Methods
The hydrochloride crystallises from 95% EtOH (solubility is ca 1%). The monohydrate is dehydrated at 100o in vacuo over H2SO4, but is hygroscopic and picks up one molecule of H2O readily. It can be sterilised at 100o if the pH of the solution is below 5.5. The nitrate has m 196-200o(dec) and is more stable than the hydrochloride. The picrolonate crystallises from H2O and is dimorphic, m 164-165o and 228-229o(dec). [Todd & Bergel J Chem Soc 364, 367 1937, J Am Chem Soc 58 1063, 1504 1936, 59 526 1937, Beilstein 27 IV 1766.]
