Chemical and physical properties of thiamin Domina Petric, MD

Essential features of the chemical structure: Conjoined pyrimidine and thiazole rings. Thiazole ring contains a quaternary nitrogen, an open C-2, and a phosphorylatable alkyl group on C-5. Amino group on C-4 of the pyrimidine ring. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Chemical structure of thiamin: Thiamin (free base) Thiamin pyrophosphate Thiochrome November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

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Thiamin nomenclature The term thiamin is the trivial designation of the compound 3-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-5-(2-hydroxyethyl)-4-methylthiazolium, known also as vitamin B1, aneurine and thiamine. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Chemical and physical properties of thiamin Free thiamin is unstable because of its quaternary nitrogen. In water it is cleaved to the thiol form. For this reason the hydrochloride and mononitrate forms are used in commerce. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Chemical and physical properties of thiamin Thiamin hydrochloride (thiamin chloride hydrochloride) is a colorless crystal that is very soluble in water (1 g/ml, thus making it a very suitable form for parenteral administration), soluble in methanol and glycerol, but practically insoluble in acetone, ether, chloroform and benzene. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Chemical and physical properties of thiamin The protonated salt has two positive charges: one associated with the pyrimidine ring one associated with the thiazole ring The mononitrate form is more stable than the hydrochloride form, but it is less soluble in water (27 mg/ml). It is used in food/feed supplementation and in dry pharmaceutical preparations. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Chemical and physical properties of thiamin Free thiamin is easily oxidized to thiamin disulfide and other derivatives, including thiochrome. Thiochrome is yellow biologically inactive product with strong blue fluorescence that can be used for the quantitative determination of thiamin. The thiazole hydroxyethyl group can be phosphorylated in vivo to form thiamin mono-, di- and triphosphates. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Chemical and physical properties of thiamin Thiamin diphosphate (thiamin pyrophosphate) is the metabolically active form sometimes referred to as cocarboxylase. November 20, 2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Literature Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008. November 20, 2018