Thiamine
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Thiamine or thiamin, also known as vitamin B1 and aneurine hydrochloride, is one of the B vitamins. It is a colorless compound with chemical formula C12H17N4OS. It is soluble in water and insoluble in alcohol. Thiamine decomposes if heated. Its chemical structure contains a pyrimidine ring and a thiazole ring.
HistoryThiamine was first discovered in 1910 by Umetaro Suzuki in Japan when researching how rice bran cured patients of beriberi. He named it aberic acid (later orizanin). He did not determine its chemical composition, nor that it was an amine. It was first crystallized by Jansen and Donath in 1926 (they named it aneurin, for antineuritic vitamin). Its chemical composition and synthesis was finally reported by Robert R. Williams in 1935. He also coined the name for it, thiamine. Thiamine phosphate derivativesThere are four known natural thiamine phosphate derivatives: thiamine monophosphate (ThMP), thiamine diphosphate (ThDP) or thiamine pyrophosphate (TPP), thiamine triphosphate (ThTP), and the recently discovered adenosine thiamine triphosphate (AThTP). Thiamine pyrophosphateThiamine pyrophosphate (TPP), also known as thiamine diphosphate (ThDP), is a coenzyme for several enzymes that catalyze the dehydrogenation (decarboxylation and subsequent conjugation to Coenzyme A) of alpha-keto acids. Examples include:
TPP is synthesized by the enzyme thiamine pyrophosphokinase, which requires free thiamine, magnesium, and adenosine triphosphate. Thiamine triphosphateThiamine triphosphate (ThTP) was long considered a specific neuroactive form of thiamine. However, recently it was shown that ThTP exists in bacteria, fungi, plants and animals suggesting a much more general cellular role. In particular in E. coli it seems to play a role in response to amino acid starvation. Adenosine thiamine triphosphateAdenosine thiamine triphosphate (AThTP) or thiaminylated adenosine triphosphate has recently been discovered in Escherichia coli where it accumulates as a result of carbon starvation. In E. coli, AThTP may account for up to 20 % of total thiamine. It also exists in lesser amounts in yeast, roots of higher plants and animal tissues. NutritionThiamine plays an important role in helping the body metabolize carbohydrates and fat to produce energy. It is essential for normal growth and development and helps to maintain proper functioning of the heart and the nervous and digestive systems. Thiamine is water-soluble and cannot be stored in the body; however, once absorbed, the vitamin is concentrated in muscle tissue. Good sourcesThiamine is found naturally in the following foods, each of which contains at least 0.1 mg of the vitamin per 28-100 g (1-3.5 oz): Green peas, Spinach, Liver, Beef, Pork, Navy beans, Nuts, Pinto beans, Bananas, Soybeans, Goji berries, Whole-grains, Breads, Yeast,the aleurone layer of unpolished rice, and Legumes. DeficiencySystemic thiamine deficiency can lead to myriad problems including neurodegeneration, wasting and death. A lack of thiamine can be caused by malnutrition, alcoholism, a diet high in thiaminase-rich foods (raw freshwater fish, raw shellfish, ferns) and/or foods high in anti-thiamine factors (tea, coffee, betel nuts)[1]. Well-known syndromes caused by thiamine deficiency include Wernicke-Korsakoff syndrome and beriberi, diseases also common with chronic alcoholism. It is thought that many people with diabetes have a deficiency of thiamine [1] and that this may be linked to some of the complications that can occur. Diagnostic testing for B1 deficiencyA positive diagnosis test for Thiamine deficiency can be ascertained by measuring the activity of transketolase in erythrocyte . Thiamine can also be seen directly in whole blood following the conversion of thiamine to a fluorescent thiochrome derivative.
Genetic diseases
Genetic diseases of thiamine transport are rare but serious. Thiamine Responsive Megaloblastic Anemia with diabetes mellitus and sensorineural deafness (TRMA)[2] is an autosomal recessive disorder caused by mutations in the gene SLC19A2,[3] a high affinity thiamine transporter. TRMA patients do not show signs of systemic thiamine deficiency, suggesting redundancy in the thiamine transport system. This has led to the discovery of a second high affinity thiamine transporter, SLC19A3.[4] Online 'Mendelian Inheritance in Man' (OMIM) 249270 ResearchHigh dosesThe RDA in most countries is set at about 1.4 mg. However, tests on volunteers at daily doses of about 50 mg have claimed an increase in mental acuity. [5] Thiamine as an insect repellentSome studies suggest that taking thiamine (vitamin B1) 25 mg to 50 mg three times per day is effective in reducing mosquito bites. A large intake of Thiamine produces a skin odor that is not detectable by humans, but is disagreeable to female mosquitoes.[6] Thiamine takes more than 2 weeks before the odor fully saturates the skin. With the advances in topical preparations there is an increasing number of Thiamine based repellent products. There is considerable anecdotal evidence of Thiamine products being effective in the field (Australia, US and Canada)[citation needed], but one study[7] found Thiamine had no effect, although amount and duration of Thiamine supplementation was unclear. AutismA 2002 pilot study administered thiamine tetrahydrofurfuryl disulfide (TTFD) rectally to ten autism spectrum children, and found beneficial clinical effect in eight.[8] This study has not been replicated and a 2006 review of thiamine by the same author did not mention thiamine's possible effect on autism.[9] References
External links
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