thiamine

ビタミンB1 　

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/03/05 02:04:29」(JST)

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For the similarly spelled nucleobase, see thymine.

Thiamine

Names
IUPAC name 3-((4-Amino-2-methyl-5-pyrimidinyl)methyl)- 5-(2-hydroxyethyl)-4-methylthiazolium chloride
Other names Aneurine Thiamin
Identifiers
CAS Number	59-43-8 Y
Beilstein Reference	3581326
ChEBI	CHEBI:18385 N
ChEMBL	ChEMBL1588 Y ChEMBL1547 N
ChemSpider	5819 Y
DrugBank	DB00152 Y
EC Number	200-425-3
Gmelin Reference	318226
Jmol interactive 3D	Image Image Image
KEGG	C00378 N
MeSH	Thiamine
PubChem	6042
UNII	X66NSO3N35 Y
InChI InChI=1S/C12H17N4OS.ClH/c1-8-11(3-4-17)18-7-16(8)6-10-5-14-9(2)15-12(10)13;/h5,7,17H,3-4,6H2,1-2H3,(H2,13,14,15);1H/q+1;/p-1 Y Key: MYVIATVLJGTBFV-UHFFFAOYSA-M Y InChI=1/C12H17N4OS.ClH/c1-8-11(3-4-17)18-7-16(8)6-10-5-14-9(2)15-12(10)13;/h5,7,17H,3-4,6H2,1-2H3,(H2,13,14,15);1H/q+1;/p-1 Key: MYVIATVLJGTBFV-REWHXWOFAY
SMILES [Cl-].Cc1c(CCO)sc[n+]1Cc1cnc(C)nc1N [Cl-].CC1=C(CCO)SC=[N+]1CC1=CN=C(C)N=C1N [Cl-].n1c(c(cnc1C)C[n+]2c(c(sc2)CCO)C)N
Properties
Chemical formula	C12H17N4OS+
Molar mass	265.35 g mol−1
Pharmacology
ATC code	A11DA01
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references

Thiamine, thiamin or vitamin B₁ (/ˈθaɪ.əmᵻn/ THY-ə-min), named as the "thio-vitamine" ("sulfur-containing vitamin") is a vitamin of the B complex. First named aneurin for the detrimental neurological effects if not present in the diet, it was eventually assigned the generic descriptor name vitamin B₁. Its phosphate derivatives are involved in many cellular processes. The best-characterized form is thiamine pyrophosphate (TPP), a coenzyme in the catabolism of sugars and amino acids. In yeast, TPP is also required in the first step of alcoholic fermentation.

All living organisms use thiamine, but it is synthesized only in bacteria, fungi, and plants. Animals must obtain it from their diet, and thus, for humans, it is an essential nutrient. Insufficient intake in birds produces a characteristic polyneuritis. In mammals, deficiency results in Korsakoff's syndrome, optic neuropathy, and a disease called beriberi that affects the peripheral nervous system (polyneuritis) and/or the cardiovascular system. Thiamine deficiency has a potentially fatal outcome if it remains untreated. In less severe cases, nonspecific signs include malaise, weight loss, irritability and confusion.

The stable and non-hygroscopic salt thiamine mononitrate is the vitamer used for flour and food fortification. Thiamine is on the World Health Organization's List of Essential Medicines, a list of the most important medication needed in a basic health system.

Chemical properties

Thiamine is a colorless organosulfur compound with a chemical formula C₁₂H₁₇N₄OS. Its structure consists of an aminopyrimidine and a thiazole ring linked by a methylene bridge. The thiazole is substituted with methyl and hydroxyethyl side chains. Thiamine is soluble in water, methanol, and glycerol and practically insoluble in less polar organic solvents. It is stable at acidic pH, but is unstable in alkaline solutions. Thiamine, which is a N-heterocyclic carbene, can be used in place of cyanide as a catalyst for benzoin condensation. Thiamine is unstable to heat, but stable during frozen storage. It is unstable when exposed to ultraviolet light and gamma irradiation. Thiamine reacts strongly in Maillard-type reactions.

Biosynthesis

A 3D representation of the TPP riboswitch with thiamine bound

Complex thiamine biosynthesis occurs in bacteria, some protozoans, plants, and fungi. The thiazole and pyrimidine moieties are bioisynthesized separately and then combined to form ThMP by the action of thiamine-phosphate synthase (EC 2.5.1.3). The biosynthetic pathways may differ among organisms. In E. coli and other enterobacteriaceae, ThMP may be phosphorylated to the cofactor ThDP by a thiamine-phosphate kinase (ThMP + ATP → ThDP + ADP, EC 2.7.4.16). In most bacteria and in eukaryotes, ThMP is hydrolyzed to thiamine, which may then be pyrophosphorylated to ThDP by thiamine diphosphokinase (thiamine + ATP → ThDP + AMP, EC 2.7.6.2).

The biosynthetic pathways are regulated by riboswitches. If there is sufficient thiamine present in the cell then the thiamine binds to the mRNAs for the enzymes that are required in the pathway and prevents their translation. If there is no thiamine present then there is no inhibition, and the enzymes required for the biosynthesis are produced. The specific riboswitch, the TPP riboswitch, is the only riboswitch identified in both eukaryotic and prokaryotic organisms.

Nutrition

Occurrence in foods

Thiamine is found in a wide variety of foods at low concentrations. Yeast, yeast extract, and pork are the most highly concentrated sources of thiamine. In general, cereal grains are the most important dietary sources of thiamine, by virtue of their wide use. Of these, whole grains contain more thiamine than refined grains, as thiamine is found mostly in the outer layers of the grain and in the germ (which are removed during the refining process). For example, 100 g of whole-wheat flour contains 0.55 mg of thiamine, while 100 g of white flour contains only 0.06 mg of thiamine. In the US, processed flour must be enriched with thiamine mononitrate (along with niacin, ferrous iron, riboflavin, and folic acid) to replace that lost in processing. In Australia, thiamine, folic acid, and iodised salt are added for the same reason.

Some other foods naturally rich in thiamine are oatmeal, flax, and sunflower seeds, brown rice, whole grain rye, asparagus, kale, cauliflower, potatoes, oranges, liver (beef, pork, and chicken), and eggs.

Dietary Reference Intakes

The Food and Nutrition Board of the U.S. Institute of Medicine updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for thiamine in 1998. The current EARs for thiamine for women and men ages 14 and up are 0.9 mg/day and 1.0 mg/day, respectively; the RDAs are 1.1 and 1.2 mg/day. RDAs are higher than EARs so as to identify amounts that will cover people with higher than average requirements. RDA for pregnancy equals 1.4 mg/day. RDA for lactation equals 1.4 mg/day. For infants up to 12 months the Adequate Intake (AI) is 0.2-0.3 mg/day. and for children ages 1–13 years the RDA increases with age from 0.5 to 0.9 mg/day. As for safety, the Food and Nutrition Board of the U.S. Institute of Medicine sets Tolerable Upper Intake Levels (known as ULs) for vitamins and minerals when evidence is sufficient. In the case of thiamine there is no UL, as there is no human data for adverse effects from high doses. The European Food Safety Authority reviewed the same safety question and also reached the conclusion that there was not sufficient evidence to set a UL for thiamine. Collectively the EARs, RDAs and ULs are referred to as Dietary Reference Intakes. For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value (%DV). Daily Values were based on 1968 RDAs and have not been updated even though RDAs have gone through several changes. For thiamine labeling purposes 100% of the Daily Value is 1.5 mg. Thus, for an adult woman, 100% DV from a food or supplement would be 136% of her RDA and 167% of her EAR.

Antagonists

Thiamine in foods can be degraded in a variety of ways. Sulfites, which are added to foods usually as a preservative, will attack thiamine at the methylene bridge in the structure, cleaving the pyrimidine ring from the thiazole ring. The rate of this reaction is increased under acidic conditions. Thiamine is degraded by thermolabile thiaminases (present in raw fish and shellfish). Some thiaminases are produced by bacteria. Bacterial thiaminases are cell surface enzymes that must dissociate from the membrane before being activated; the dissociation can occur in ruminants under acidotic conditions. Rumen bacteria also reduce sulfate to sulfite, therefore high dietary intakes of sulfate can have thiamine-antagonistic activities.

Plant thiamine antagonists are heat-stable and occur as both the ortho- and para-hydroxyphenols. Some examples of these antagonists are caffeic acid, chlorogenic acid, and tannic acid. These compounds interact with the thiamine to oxidize the thiazole ring, thus rendering it unable to be absorbed. Two flavonoids, quercetin and rutin, have also been implicated as thiamine antagonists.

Absorption and transport

Absorption

Thiamine is released by the action of phosphatase and pyrophosphatase in the upper small intestine. At low concentrations, the process is carrier-mediated, and, at higher concentrations, absorption occurs via passive diffusion. Active transport is greatest in the jejunum and ileum (it is inhibited by alcohol consumption and by folic deficiency). Decline in thiamine absorption occurs at intakes above 5 mg/day. The cells of the intestinal mucosa have thiamine pyrophosphokinase activity, but it is unclear as to whether the enzyme is linked to active absorption. The majority of thiamine present in the intestine is in the pyrophosphorylated form ThDP, but when thiamine arrives on the serosal side of the intestine it is often in the free form. The uptake of thiamine by the mucosal cell is likely coupled in some way to its phosphorylation/dephosphorylation. On the serosal side of the intestine, evidence has shown that discharge of the vitamin by those cells is dependent on Na⁺-dependent ATPase.

Bound to serum proteins

The majority of thiamine in serum is bound to proteins, mainly albumin. Approximately 90% of total thiamine in blood is in erythrocytes. A specific binding protein called thiamine-binding protein (TBP) has been identified in rat serum and is believed to be a hormone-regulated carrier protein important for tissue distribution of thiamine.

Cellular uptake

Uptake of thiamine by cells of the blood and other tissues occurs via active transport and passive diffusion. The brain requires a much greater amount of thiamine than in other cells of the body. Much of ingested thiamine never reaches the brain because of passive diffusion and the blood brain barrier. About 80% of intracellular thiamine is phosphorylated and most is bound to proteins. In some tissues, thiamine uptake and secretion appears to be mediated by a soluble thiamine transporter that is dependent on Na⁺ and a transcellular proton gradient.

Tissue distribution

Human storage of thiamine is about 25 to 30 mg, with the greatest concentrations in skeletal muscle, heart, brain, liver, and kidneys. ThMP and free (unphosphorylated) thiamine is present in plasma, milk, cerebrospinal fluid, and, it is presumed, all extracellular fluids. Unlike the highly phosphorylated forms of thiamine, ThMP and free thiamine are capable of crossing cell membranes. Thiamine contents in human tissues are less than those of other species.

Excretion

Thiamine and its acid metabolites (2-methyl-4-amino-5-pyrimidine carboxylic acid, 4-methyl-thiazole-5-acetic acid, and thiamine acetic acid) are excreted principally in the urine.

Thiamine phosphate derivatives and function

Thiamine is usually considered as the transport form of the vitamin. There are five known natural thiamine phosphate derivatives: thiamine monophosphate (ThMP), thiamine diphosphate (ThDP), also sometimes called thiamine pyrophosphate (TPP), thiamine triphosphate (ThTP), and the recently discovered adenosine thiamine triphosphate (AThTP), and adenosine thiamine diphosphate (AThDP). While the coenzyme role of thiamine diphosphate is well-known and extensively characterized, the non-coenzyme action of thiamine and derivatives may be realized through binding to a number of recently identified proteins which do not use the catalytic action of thiamine diphosphate

Thiamine diphosphate

No physiological role is known for ThMP; however, the diphosphate is physiologically relevant. The synthesis of thiamine diphosphate (ThDP), also known as thiamine pyrophosphate (TPP) or cocarboxylase, is catalyzed by an enzyme called thiamine diphosphokinase according to the reaction thiamine + ATP → ThDP + AMP (EC 2.7.6.2). ThDP is a coenzyme for several enzymes that catalyze the transfer of two-carbon units and in particular the dehydrogenation (decarboxylation and subsequent conjugation with coenzyme A) of 2-oxoacids (alpha-keto acids). Examples include:

• Present in most species
  • pyruvate dehydrogenase and 2oxoglutarate dehydrogenase (also called α-ketoglutarate dehydrogenase)
  • branched-chain α-keto acid dehydrogenase
  • 2-hydroxyphytanoyl-CoA lyase
  • transketolase
• Present in some species:
  • pyruvate decarboxylase (in yeast)
  • several additional bacterial enzymes

The enzymes transketolase, pyruvate dehydrogenase (PDH), and 2-oxoglutarate dehydrogenase (OGDH) are all important in carbohydrate metabolism. The cytosolic enzyme transketolase is a key player in the pentose phosphate pathway, a major route for the biosynthesis of the pentose sugars deoxyribose and ribose. The mitochondrial PDH and OGDH are part of biochemical pathways that result in the generation of adenosine triphosphate (ATP), which is a major form of energy for the cell. PDH links glycolysis to the citric acid cycle, while the reaction catalyzed by OGDH is a rate-limiting step in the citric acid cycle. In the nervous system, PDH is also involved in the production of acetylcholine, a neurotransmitter, and for myelin synthesis.

Thiamine 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

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 tissue.

Adenosine thiamine diphosphate

Adenosine thiamine diphosphate (AThDP) or thiaminylated adenosine diphosphate exists in small amounts in vertebrate liver, but its role remains unknown.

Deficiency

Thiamine derivatives and thiamine-dependent enzymes are present in all cells of the body, thus a thiamine deficiency would seem to adversely affect all of the organ systems. However, the nervous system is particularly sensitive to thiamine deficiency, because of its dependence on oxidative metabolism.

Thiamine deficiency commonly presents subacutely and can lead to metabolic coma and death. A lack of thiamine can be caused by malnutrition, 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) and by grossly impaired nutritional status associated with chronic diseases, such as alcoholism, gastrointestinal diseases, HIV-AIDS, and persistent vomiting. It is thought that many people with diabetes have a deficiency of thiamine and that this may be linked to some of the complications that can occur.

Well-known syndromes caused by thiamine deficiency include beriberi, Wernicke-Korsakoff syndrome, and optic neuropathy.

Beriberi

Beriberi is a neurological and cardiovascular disease. The three major forms of the disorder are dry beriberi, wet beriberi, and infantile beriberi. A fourth form, gastrointestinal beriberi, was recognized in 2004.

• Dry beriberi is characterized principally by peripheral neuropathy consisting of symmetric impairment of sensory, motor, and reflex functions affecting distal more than proximal limb segments and causing calf muscle tenderness.

However, it has been recently recognized that peripheral neuropathy (tingling or numbness in the extremities) due to thiamine deficiency could also present with axonal neuropathy (partial paralysis or sensory loss). Peripheral neuropathy can present with subacute motor axonal neuropathy mimicking Guillain–Barré syndrome; or as a large fibre proprioceptive central-peripheral axonal neuropathy presenting as a subacute sensory ataxia.

• Wet beriberi is associated with mental confusion, muscular atrophy, edema, tachycardia, cardiomegaly, and congestive heart failure in addition to peripheral neuropathy.
• Infantile beriberi occurs in infants breast-fed by thiamin-deficient mothers (who may show no sign of thiamine deficiency). Infants may manifest cardiac, aphonic, or pseudomeningitic forms of the disorder. Infants with cardiac beriberi frequently exhibit a loud piercing cry, vomiting, and tachycardia. Convulsions are not uncommon, and death may ensue if thiamine is not administered promptly.
• Gastrointestinal beriberi is associated with nausea, vomiting, abdominal pain, and lactic acidosis.

Following thiamine treatment, rapid improvement occurs, in general, within 24 hours. Improvements of peripheral neuropathy may require several months of thiamine treatment.

Alcoholic brain disease

Nerve cells and other supporting cells (such as glial cells) of the nervous system require thiamine. Examples of neurologic disorders that are linked to alcohol abuse include Wernicke's encephalopathy (WE), Korsakoff’s psychosis (alcohol amnestic disorder), Wernicke–Korsakoff syndrome as well as varying degrees of cognitive impairment.

Wernicke's encephalopathy is the most frequently encountered manifestation of thiamine deficiency in Western society, though it may also occur in patients with impaired nutrition from other causes, such as gastrointestinal disease, those with HIV-AIDS, and with the injudicious administration of parenteral glucose or hyperalimentation without adequate B-vitamin supplementation. This is a striking neuro-psychiatric disorder characterized by paralysis of eye movements, abnormal stance and gait, and markedly deranged mental function.

Korsakoff's syndrome is, in general, considered to occur with deterioration of brain function in patients initially diagnosed with WE. This is an amnestic-confabulatory syndrome characterized by retrograde and anterograde amnesia, impairment of conceptual functions, and decreased spontaneity and initiative.

Alcoholics may have thiamine deficiency because of the following:

• Inadequate nutritional intake: Alcoholics tend to intake less than the recommended amount of thiamine.
• Decreased uptake of thiamine from the GI tract: Active transport of thiamine into enterocytes is disturbed during acute alcohol exposure.
• Liver thiamine stores are reduced due to hepatic steatosis or fibrosis.
• Impaired thiamine utilization: Magnesium, which is required for the binding of thiamine to thiamine-using enzymes within the cell, is also deficient due to chronic alcohol consumption. The inefficient utilization of any thiamine that does reach the cells will further exacerbate the thiamine deficiency.
• Ethanol per se inhibits thiamine transport in the gastrointestinal system and blocks phosphorylation of thiamine to its cofactor form (ThDP).

Following improved nutrition and the removal of alcohol consumption, some impairments linked with thiamine deficiency are reversed, in particular poor brain functionality, although in more severe cases, Wernicke–Korsakoff syndrome leaves permanent damage. (See delirium tremens.)

Optic neuropathy

Optic neuropathy can also occur in thiamine deficiency and is characterized by bilateral visual loss, cecocentral scotomas and impaired colour perception. The ophthalmological findings usually can show a bilateral oedema of the optic disk in the acute phase, followed by a bilateral optic atrophy.

Thiamine deficiency in poultry

As most feedstuffs used in poultry diets contain enough quantities of vitamins to meet the requirements in this species, deficiencies in this vitamin do not occur with commercial diets. This was, at least, the opinion in the 1960s.

Mature chickens show signs 3 weeks after being fed a deficient diet. In young chicks, it can appear before 2 weeks of age.

Onset is sudden in young chicks. There is anorexia and an unsteady gait. Later on, there are locomotor signs, beginning with an apparent paralysis of the flexor of the toes. The characteristic position is called "stargazing", meaning a chick "sitting on its hocks and the head in opisthotonos".

Response to administration of the vitamin is rather quick, occurring a few hours later.

Differential diagnosis include riboflavin deficiency and avian encephalomyelitis. In riboflavin deficiency, the "curled toes" is a characteristic symptom. Muscle tremor is typical of avian encephalomyelitis. A therapeutic diagnosis can be tried by supplementing thiamine only in the affected bird. If the animals do not respond in a few hours, thiamine deficiency can be excluded.

Thiamine deficiency in ruminants

Polioencephalomalacia (PEM) is the most common thiamine deficiency disorder in young ruminant and nonruminant animals. Symptoms of PEM include a profuse, but transient, diarrhea, listlessness, circling movements, star gazing or opisthotonus (head drawn back over neck), and muscle tremors. The most common cause is high-carbohydrate feeds, leading to the overgrowth of thiaminase-producing bacteria, but dietary ingestion of thiaminase (e.g., in bracken fern), or inhibition of thiamine absorption by high sulfur intake are also possible. Another cause of PEM is Clostridium sporogenes or Bacillus aneurinolyticus infection. These bacteria produce thiaminases that will cause an acute thiamine deficiency in the affected animal.

Idiopathic paralytic disease in wild birds, fish

Recently, thiamine deficiency has been identified as the cause of a paralytic disease affecting wild birds in the Baltic Sea area dating back to 1982. In this condition, there is difficulty in keeping the wings folded along the side of the body when resting, loss of the ability to fly and voice, with eventual paralysis of the wings and legs and death. It affects primarily 0.5–1 kg sized birds such as the herring gull (Larus argentatus), common starling (Sturnus vulgaris) and common eider (Somateria mollissima). Researches noted, "Because the investigated species occupy a wide range of ecological niches and positions in the food web, we are open to the possibility that other animal classes may suffer from thiamine deficiency as well."^p. 12006

In the counties of Blekinge and Skåne (south-most Sweden) mass deaths of especially herring gull but also other species has been observed since the early 2000s. More recently, species of other classes seems to be affected. High mortality of salmon (Salmo salar) in the river Mörrumsån is reported, and the last years mammals like Eurasian Elk (Alces alces) has suffered death in unusual high number. Lack of thiamine is the common denominator where analysis is done. The County Administrative Board of Blekinge did in April 2012 find the situation so alarming that they asked the Swedish government to set up a closer investigation.

Analysis and diagnostic testing

Oxidation of thiamine derivatives to fluorescent thiochromes by potassium ferricyanide under alkaline conditions

A positive diagnosis test for thiamine deficiency can be ascertained by measuring the activity of the enzyme transketolase in erythrocytes (Erythrocyte Transketolase Activation Assay). Thiamine, as well as its phosphate derivatives, can also be detected directly in whole blood, tissues, foods, animal feed, and pharmaceutical preparations following the conversion of thiamine to fluorescent thiochrome derivatives (Thiochrome Assay) and separation by high-performance liquid chromatography (HPLC). In recent reports, a number of Capillary Electrophoresis (CE) techniques and in-capillary enzyme reaction methods have emerged as potential alternative techniques for the determination and monitoring of thiamine in samples. The normal thiamine concentration in EDTA-blood is about 20-100 µg/l.

Genetic diseases

Genetic diseases of thiamine transport are rare but serious. Thiamine responsive megaloblastic anemia (TRMA) with diabetes mellitus and sensorineural deafness is an autosomal recessive disorder caused by mutations in the gene SLC19A2, 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. Leigh disease (subacute necrotising encephalomyelopathy) is an inherited disorder that affects mostly infants in the first years of life and is invariably fatal. Pathological similarities between Leigh disease and WE led to the hypothesis that the cause was a defect in thiamine metabolism. One of the most consistent findings has been an abnormality of the activation of the pyruvate dehydrogenase complex.

Mutations in the SLC19A3 gene have been linked to Biotin-Thiamine Responsive Basal Ganglia Disease which is treated with pharmacological doses of thiamine and biotin, another B vitamin.

Other disorders in which a putative role for thiamine has been implicated include subacute necrotising encephalomyelopathy, opsoclonic cerebellopathy (a paraneoplastic syndrome), and Nigerian seasonal ataxia. In addition, several inherited disorders of ThDP-dependent enzymes have been reported, which may respond to thiamine treatment.

History

Thiamine was the first of the water-soluble vitamins to be described, leading to the discovery of more such trace compounds essential for survival and to the notion of vitamin.

In 1884, Kanehiro Takaki (1849–1920), a surgeon general in the Japanese navy, rejected the previous germ theory for beriberi and hypothesized that the disease was due to insufficiencies in the diet instead. Switching diet on a navy ship, he discovered that substituting a diet of white rice only, with one also containing barley, meat, milk, bread, and vegetables nearly eliminated beriberi on a 9-month sea voyage. However, Takaki had added many foods to the successful diet and he incorrectly attributed the benefit to increased nitrogen intake, as vitamins were unknown substances at the time. Nor was the Navy convinced of the need for so expensive a program of dietary improvement, and many men continued to die of beriberi, even during the Russo-Japanese war of 1904–5. Not until 1905, after the anti-beriberi factor had been discovered in rice bran (removed by polishing into white rice) and in brown barley rice, was Takaki's experiment rewarded by making him a baron in the Japanese peerage system, after which he was affectionately called "Barley Baron".

The specific connection to grain was made in 1897 by Christiaan Eijkman (1858–1930), a military doctor in the Dutch Indies, discovered that fowl fed on a diet of cooked, polished rice developed paralysis, which could be reversed by discontinuing rice polishing. He attributed beriberi to a nerve poison in the endosperm of rice, from which the outer layers of the grain gave protection to the body. An associate, Gerrit Grijns (1865–1944), correctly interpreted the connection between excessive consumption of polished rice and beriberi in 1901: He concluded that rice contains an essential nutrient in the outer layers of the grain that is removed by polishing.

Eijkman was eventually awarded the Nobel Prize in Physiology and Medicine in 1929, because his observations led to the discovery of vitamins. These compounds were named by Polish biochemist Casimir Funk. In 1911, Casimir Funk isolated the antineuritic substance from rice bran that he called a "vitamine" (on account of its containing an amino group). Dutch chemists, Barend Coenraad Petrus Jansen (1884–1962) and his closest collaborator Willem Frederik Donath (1889–1957), went on to isolate and crystallize the active agent in 1926, whose structure was determined by Robert Runnels Williams (1886–1965), a US chemist, in 1934. Thiamine (“sulfur-containing vitamin”) was synthesized in 1936 by the same group.

Thiamine was first named "aneurin" (for anti-neuritic vitamin). Sir Rudolph Peters, in Oxford, introduced thiamine-deprived pigeons as a model for understanding how thiamine deficiency can lead to the pathological-physiological symptoms of beriberi. Indeed, feeding the pigeons upon polished rice leads to an easily recognizable behavior of head retraction, a condition called opisthotonos. If not treated, the animal will die after a few days. Administration of thiamine at the stage of opithotonos will lead to a complete cure of the animal within 30 min. As no morphological modifications were observed in the brain of the pigeons before and after treatment with thiamine, Peeters introduced the concept of biochemical lesion.

When Lohman and Schuster (1937) showed that the diphosphorylated thiamine derivative (thiamine diphosphate, ThDP) was a cofactor required for the oxydative decarboxylation of pyruvate, (a reaction now known to be catalyzed by pyruvate dehydrogenase), the mechanism of action of thiamine in the cellular metabolism seemed to be elucidated. At present, this view seems to be oversimplified: Pyruvate dehydrogenase is only one of several enzymes requiring thiamine diphosphate as a cofactor; moreover, other thiamine phosphate derivatives have been discovered since then, and they may also contribute to the symptoms observed during thiamine deficiency.

Finally, the mechanism by which the thiamine moiety of ThDP exerts its coenzyme function by proton substitution on position 2 of the thiazoliumring was elucidated by Ronald Breslow in 1958.

Research

Research in the field mainly concerns the mechanisms by which thiamine deficiency leads to neuronal death in relation to Wernicke Korsakoff Psychosis. Another important theme focuses on understanding of the molecular mechanisms involved in ThDP catalysis. Research has been devoted to the understanding of the possible non-cofactor roles of other derivatives such as ThTP and AThTP.

Mechanism by which thiamine deficiency leads to selective neuronal death

Experimentally induced beriberi polyneuropathy in chickens may be a good model for studying these forms of neuropathy in view of diagnosis and treatment. From studies using rat models, a link between thiamine deficiency and colon carcinogenesis was suggested. Rat models are also used in research of Wernicke's encephalopathy. Thiamine deprived mice are a classic model of systemic oxidative stress, used in research of Alzheimer’s disease.

Catalytic mechanisms in thiamine diphosphate-dependent enzymes

A lot of work is devoted to the understanding of the interplay between ThDP and ThDP-dependent enzymes in catalysis.

Non-cofactor roles of thiamine derivatives

Thiamine compounds other than ThDP exist in most cells from many organisms, including bacteria, fungi, plants and animals. Among those compounds are thiamine triphosphate (ThTP) and adenosine thiamine triphosphate (AThTP). They are thought to have non-cofactor roles, though at present it is not known to what extent they participate in the symptoms. A recent study revealed allosteric regulation of metabolic enzymes by non-coenzyme forms of thiamin, which may be responsible for the action of thiamin and derivatives as metabolic regulators

New thiamine derivatives

New thiamine phosphate derivatives continue to be discovered, emphasizing the complexity of thiamine metabolism.

Thiamine derivatives with improved pharmacokinetics may prove effective in alleviating the symptoms of thiamine deficiency and other thiamine-related conditions such as impaired glucose metabolism in diabetes. These compounds include allithiamine, prosultiamine, fursultiamine, benfotiamine, and sulbutiamine, among others.

Persistent carbenes

The production of furoin from furfural is catalyzed by thiamine through a relatively stable carbene (an organic molecule containing unbonded valence electrons pairs at a carbon center). This reaction, studied in 1957 by R. Breslow, was the first evidence for the existence of persistent carbenes.

See also

• Vitamin B₁ analogue

References

External links

• "Thiamine"
• "Branched-Chain Amino Acid Metabolism" at ncbi.nlm.nih.gov
• Thiamin deficiency in poultry
• Type of vitamin B₁ could treat common cause of blindness
• Thiamin bound to proteins in the PDB

UpToDate Contents

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• 1. 水溶性ビタミンの概要 overview of water soluble vitamins
• 2. 小児における後天性末梢性ニューロパチーの概要 overview of acquired peripheral neuropathies in children
• 3. 持続的なアルコール依存症患者における栄養状態 nutritional status in patients with sustained heavy alcohol use
• 4. ウェルニッケ脳症 wernicke encephalopathy
• 5. メープルシロップ尿症の概要 overview of maple syrup urine disease

English Journal

• A novel method for determining vitamin B(1) in a wide variety of foodstuffs with or without polyphenols.

• Yoshida M, Hishiyama T, Ogawara M, Fuse K, Mori M, Igarashi T, Taniguchi M.SourceJapan Food Research Laboratories, 3-1 Toyotsu-cho, Suita-shi, Osaka 564-0051, Japan; Mimasaka University, 50 Kitazono-cho, Tsuyama-shi, Okayama 708-8511, Japan. Electronic address: yosidami@jfrl.or.jp.
• Food chemistry.Food Chem.2012 Dec 15;135(4):2387-92. doi: 10.1016/j.foodchem.2012.07.044. Epub 2012 Jul 15.
• Certain foodstuffs exhibit matrix interference effects on the vitamin B(1) analysis prescribed in the official methods of the European Union, AOAC International, and Japan. In this study, we demonstrated that one of the problematic polyphenols in green tea or cocoa was tannin. For these matrices, th
• PMID 22980817

• Rapid determination of thiamine, riboflavin, niacinamide, pantothenic acid, pyridoxine, folic acid and ascorbic acid in Vitamins with Minerals Tablets by high-performance liquid chromatography with diode array detector.

• Jin P, Xia L, Li Z, Che N, Zou D, Hu X.SourceDepartment of Pharmaceutical Science, Beijing Hospital of the Ministry of Health, No. 1 Dahua Road, Dongcheng District, Beijing 100730, China. Electronic address: j790101@163.com.
• Journal of pharmaceutical and biomedical analysis.J Pharm Biomed Anal.2012 Nov;70:151-7. doi: 10.1016/j.jpba.2012.06.020. Epub 2012 Jun 23.
• A simple, isocratic, and stability-indicating high-performance liquid chromatography (HPLC) method has been developed for the rapid determination of thiamine (VB(1)), niacinamide (VB(3)), pyridoxine (VB(6)), ascorbic acid (VC), pantothenic acid (VB(5)), riboflavin (VB(2)) and folic acid (VB(9)) in V
• PMID 22785377

Japanese Journal

• 症例 リン酸チアミンジスルフィド(ビタミンB誘導体)によるアナフィラキシーショックの1例

• 高橋 ユエ,蒲原 毅,藤村 奈緒 [他]
• Journal of environmental dermatology and cutaneous allergology 6(4), 368-372, 2012-07
• NAID 40019406146

• 症例報告 Wernicke脳症を発症した腹膜透析患者の1例

• 吉川 美喜子,原田 幸児,住田 鋼一 [他]
• 日本透析医学会雑誌 45(7), 581-585, 2012-07
• NAID 40019400571

Related Links

• thiamineの意味 - goo辞書 英和和英

thiamineとは。意味や和訳。[名]チアミン（ ビタミンB1の国際的名称） - 80万項目以上収録、例文・コロケーションが豊富な無料英和和英辞典。 ... "the exact opposite"（真逆） 英語では「真逆」にあたるさまざまな表現があります。「君の ...

• Thiamine: MedlinePlus Supplements

Thiamine is a vitamin, also called vitamin B1. Vitamin B1 is found in many foods including yeast, cereal grains, beans, nuts, and meat. It is often used in combination with other B vitamins, and found in many vitamin B complex ...

• Thiamine (Vitamin B1): Uses, Side Effects, Interactions ...

Overview Information Thiamine is a vitamin, also called vitamin B1. Vitamin B1 is found in many foods including yeast, cereal grains, beans, nuts, and meat. It is often used in combination with other B vitamins, and found ...

Related Pictures

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★リンクテーブル★

リンク元	「チアミン」「ビタミンB1」「ピルビン酸デヒドロゲナーゼ」「ビタミンB」「vitamin B1」
拡張検索	「thiamine disulfide phosphate」「thiamine nitrate」
関連記事	「thiamin」

「チアミン」

　　[★]

英

thiamine

商

M.V.I.、M.V.I.-12キット、アクタミン、アミグランド、アミノレバンEN配合、アリチア配合、アリナミン、アリナミンF、エスアリネート、エルネオパ1号、エレンタールP乳幼児用配合、エレンタール配合、エンシュア・リキッド、オーツカＭＶ、グラビタン、コンベルビー、サブビタン、ジアイナミックス、ジアノイナミン、シーパラ、シグマビタン、シグマビタン配合、ジセタミン、ダイビタミックス、ダイメジン・マルチ、ダイメジンスリービー配合、ダイヤビタン、チアデラ、チアミン塩化物塩酸塩、ツインラインNF配合、ツインライン配合、トライビー、トリドセラン配合、ナイロジン、ネオM.V.I.-9、ネオパレン1号、ネオラミン・スリービー、ネオラミン・マルチＶ、ノイビタ、ノイロビタン配合、ノルニチカミン、バイオゲン、パレセーフ、パンビタン末、ビーカップ、ビースリミン、ビーフリード、ビーワン、ビオトーワ、ビタジェクト、ビタダン配合、ビタノイリン、ビタファント、ビタファントＦ、ビタマル配合、ビタミンB1、ビタメジン、ビタメジン配合、ビタルファ、フェニルアラニン除去ミルク配合、プラチアミン、フルカリック1号、フルスルチアミン、フルメチ、プレビタS、ベストン、ヘパンED配合、ベルミンビー、マルタミン、ムツタミン、メタボリン、メタボリンG、ラコールNF配合、ラコール配合、ロイシン・イソロイシン・バリン除去ミルク配合、ロートエキス、ロンベリン、ワッサーV配合、塩酸B1、塩酸チアミン

関

ビタミンB1

ビタミンＢ１剤

「ビタミンB1」

　　[★]

英

vitamine B1

同

チアミン thiamine、塩酸チアミン thiamine hydrochloride、ビタミンB1塩酸塩、アノイリン aneurine

商

アミグランド、パレセーフ、ビーフリード

関

ビタミン、チアミン二リン酸 thiamine pyrophosphate チアミンピロリン酸 TPP

• 水溶性ビタミン

機能

• 補酵素

• 体内でリン酸化されてピロリン酸エステルであるチアミン二リン酸(TPP)となり機能する。
• α-ケト酸の酸化的脱炭酸反応(oxidative decarboxylation)、ケトール形成反応に関わる。
• 1. 解糖系からTCA回路を繋ぐ反応：チアミン二リン酸はピルビン酸デヒドロゲナーゼに非共有結合して、以下の脱炭酸反応を触媒

• ピルビン酸 + CoASH + NAD⁺　－(ピルビン酸デヒドロゲナーゼ)→　アセチルCoA + NADH + CO₂

• 2. TCA回路の反応

• α-ケトグルタル酸 + CoASH + NAD⁺ －(α-keto glutarate dehydrogenase)→　サクシニルCoA + NADH + CO₂

• 3. branched-chain ketoacid dehyrogenase: involved in metabolism of branched-chain amino acid; deficiency results in maple syrup urine disease

• 4. transketolase; hexose monophosphate shunt

• 5. 酵母などではアルコール発酵を行うピルビン酸デカルボキシラーゼ(ピルビン酸からCO₂を除去してアセトアルデヒドを産生)の補酵素として重要

• ピルビン酸－(ピルビン酸デカルボキシラーゼ)→アセトアルデヒド + CO₂

臨床関連

• ビタミンB₁欠乏症

• 脚気
• ウェルニッケ脳症、コルサコフ症候群

「ピルビン酸デヒドロゲナーゼ」

　　[★]

英

pyruvate dehydrogenase

関

ピルビン酸脱水素酵素、ピルビン酸、ピルビン酸デヒドロゲナーゼ複合体

概要

• ピルビン酸からアセチルCoAを生成し、クエン酸回路に投入するための酵素
• 逆反応を触媒する酵素はない

反応

ピルビン酸+NAD++SH-CoA　→　アセチルCoA+NADH+CO2 

補酵素

• チアミン二リン酸(TPP)　←　ビタミンB1　thiamine
• FAD　←　ビタミンB2 リボフラビン　riboflavin
• NAD⁺　←　ビタミンB3　ナイアシン　niacin
• 補酵素A(CoA)　←　ビタミンB5
• リポアミド

臨床関連

不足

• ピルビン酸脱水素酵素欠損症　

• ピルビン酸、アラニンの蓄積→乳酸アシドーシス

アルコール中毒によるビタミンB1不足によっても生じる

「ビタミンB」

　　[★]

英

vitamin B

関

ビタミン

thiamine、niacin、pyridoxine

「vitamin B1」

　　[★]

同

thiamine

同

thiamin

「thiamine disulfide phosphate」

　　[★]

• リン酸チアミンジスルフィド

関

thiamine disulfide、thiamine disulfide nitrate

「thiamine nitrate」

　　[★]

• 硝酸チアミン

関

thiamin、thiamine、thiamine hydrochloride

「thiamin」

　　[★] ビタミンB1、チアミン, thiamine