Thiamine

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Thiamine
Systematic name	Thiamine
Molecular formula	C12H17N4OS
Molecular mass	266.4 g/mol
Density	x.xxx g/cm3
Melting point	248-250 °C (hydrochloride salt)
Boiling point	xx.x °C
CAS number	[59-43-8]
SMILES	xxxx
Disclaimer and references

For the similarly-spelled nucleic acid, see Thymine

Thiamine or thiamin, also known as vitamin B₁, 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.

Thiamine was first discovered in 1910 by Umetaro Suzuki in Japan when researching how rice bran cured patients of beriberi. He named it aberic acid. 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, thiamin. There are four known natural thiamine phosphate derivatives: thiamine monophosphate (ThMP), thiamine diphosphate (ThDP), thiamine triphosphate (ThTP) and the recently discovered adenine thiamine triphopshate (AThTP).

In mammals, thiamine diphosphate (ThDP) or thiamine pyrophosphate (TPP) is a coenzyme for pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, branched-chain alpha-keto acid dehydrogenase, 2-hydroxyphytanoyl-CoA lyase, and transketolase. The first two of these enzymes function in the metabolism of carbohydrates, while transketolase functions in the pentose phosphate pathway to synthesize NADPH and the pentose sugars deoxyribose and ribose. ThDP is also the cofactor of pyruvate decarboxylase in yeast and of several bacterial enzymes. In general, TPP functions as a cofactor for enzymes that catalyze the dehydrogenation (decarboxylation and subsequent conjugation to Coenzyme A) of alpha-keto acids. TPP is synthesized by the enzyme thiamine pyrophosphokinase, which requires free thiamine, magnesium, and adenosine triphosphate.

Thiamine 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 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.

Contents 1 Nutrition 1.1 Good sources 1.2 Deficiency 1.2.1 Diagnostic Testing for B1 Deficiency 2 Overdose 3 Genetic diseases 4 Research 4.1 High doses 4.2 Benefits for autism 5 References 6 External links

[edit] Nutrition

Also known as vitamin B1, thiamine plays an important role in helping the body convert carbohydrates and fat into 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.

[edit] Good sources

Thiamine is found naturally in the following foods, each of which contains at least 0.1mg of the vitamin per 28-100g (1-3.5oz): Green peas, Spinach, Liver, Beef, Pork, Navy beans, Nuts, Pinto beans, Bananas, Soybeans, Whole-grain and Enriched Cereals, Breads, Yeast,the aleurone layer of unpolished rice, and Legumes.

[edit] Deficiency

Systemic 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.

[edit] Diagnostic Testing for B1 Deficiency

A positive diagnosis test for Thiamine deficiency can be ascertained by measuring the activity of transketolase in erythrocyte . Thiamine can also be measured directly in whole blood following the conversion of thiamine to a fluorescent thiochrome derivative.

[edit] Overdose

The only known cases of thiamine overdose occurred with thiamine injections also known as anabolic steroids. Thiamine injection may result in anaphylactic reactions.

[edit] 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]

Mendelian Inheritance in Man (OMIM) 249270

[edit] Research

[edit] High doses

The RDA in most countries is set at about 1.4 mg. However, tests on volunteers at daily doses of about 50 mg have shown an increase in mental acuity. ^[5]

[edit] Benefits for autism

Derrick Lonsdale lead a successful study on the treatment of autism spectrum children with thiamine.^[6] This work is controversial linking diet with autism.

[edit] References

[1]

[edit] External links

• Links to external chemical sources