Vitamin BJ

Vitamin Bj 2 is concerned in the biosynthesis of methyl groups of choline and methionine. 

Determination of structural features. The ultraviolet spectrum has been of value in the determination of the structure of several vitamins. Thus the presence of an a-naphthoquinone system in vitamin K was first detected by this means. Also the 4-methylthiazole and the 2 5-dimethyl-6-aminopyridine system was first identified in vitamin Bj (thiamine), a- and /3-Ionones can be distinguished since the former contains two conjugated chromophores and the latter three conjugated chromophores. 

Thiazolium salts with alkyl (103, 722), arylalkyl (116), aryl (305), or heteroaryl (96) substituents on the nitrogen have been also prepared by this procedure. As in the thiazole series, N-substituted thioamides can be formed directly in the reaction mixture from phosphorus pentasulfide and N-substituted amides (127). These methods are important in the synthesis of thiamine 102 (vitamin Bj) (Scheme 45). 

As noted by Robinson and Strachan (1), after considerable activity in the period 1885 to 1895 thiazolecarboxylic acids received little attention until 1935. Isolation of 4-methyl-5-thiazolecarboxylic acid after degradation of vitamin Bj gave new interest to the chemistry of these compounds. 

Water-Soluble Thiamine (vitamin Bj) Thiamine pyrophosphate... 

Thiamine, whose structure is shown in Figure 18.17, is known as vitamin Bj and is essential for the prevention of beriberi, a nervous system disease that has occurred in the Far East for centuries and has resulted in considerable sickness and death in these countries. (As recently as 1958, it was the fourth leading cause of death in the Philippine Islands.) It was shown in 1882 by the director-general of the medical department of the Japanese nayt that beriberi could be prevented by dietary modifications. Ten years later, Christiaan Eijkman, a Dutch medical scientist working in Java, began research that eventually showed that thiamine was the... 

Important organic applications are to the determination of quinine and the vitamins riboflavin (vitamin B2) and thiamine (vitamin Bj). Riboflavin fluoresces in aqueous solution thiamine must first be oxidised with alkaline hexacyanoferrate(III) solution to thiochrome, which gives a blue fluorescence in butanol solution. Under standard conditions, the net fluorescence of the thiochrome produced by oxidation of the vitamin Bj is directly proportional to its concentration over a given range. The fluorescence can be measured either by reference to a standard quinine solution in a null-point instrument or directly in a spectrofluorimeter.27... 

Another way of demonstrating currently achievable performance with the above system is shown in Table 13. Here, the peak counts/sec from a typical empty suitcase, leather attache case, and the leather attache case containing six sticks of Dynamite are compared to the background level. The attache case, in both cases, was also filled with common nitrogen-rich materials such as wool, vitamins Bj and B12t pills, rayon, saccharin, silk and other materials such as paper, cotton and brass ... 

D Aneurin A.S. (A.S.) Betabion (Merck) Lophakomp (Lomapharm) Vitamin Bj Hevert (Hevert) Vitamin Bplnjektopas (Pascoe)... 

Amines, amides e.g. hexamine, urea derivatives, melamine resins [1, 2] peptides [3-6] Triazines [7] Vitamin Bj, B2, Bj NH2... 

True. Excessive alcohol use can lead to serious damage to mental health. Depression, anxiety, delusions and negative changes in personality can occur. Korsakoff s psychosis occurs in some excessive users of alcohol. This form of dementia results in disorientation, loss of memory and lowered intellectual abilities. It is reversible in some sufferers through the administration of thiamine (vitamin Bj. 

Although TLC analysis of vitamin Bj has been reported in food and mammalian tissues, [3,4] we eould not find any arfieles for preparation of vitamin Bj and related compounds using TLC. 

Callmer, K. and Davies, L., Separation and determination of vitamin Bj, B2, Bj, and nicotinamide in commercial vitamin preparations using high-performance cation-exchange chromatography, Chromatographia, 7, 644, 1974. 

It soon became apparent that the biologically active forms of Vitamin Bj.2 contained the unique Co—C-a-bond, and the instability of these covalent compounds to visible light facilitated observations on the occurrence of functional corrinoids in a number of enzymes. Deoxyadenosyl-cobalamin was found to be the most abundant corrinoid in bacteria (24) and in mammalian liver (25). Methylcobalamin was found in Escherichia coli (26), calf liver and human blood plasma (27), and also in a number of Clostridia (28). 

One of the most promising applications of nuclear magnetic resonance to vitamin Bj.2-chemistry is the use of carbon-13 NMR (145). The use of 13C fourier transform NMR has greatly increased the applicability of 13C NMR in that it permits one to obtain high quality spectra with natural abundance 13C. 

SOME STEPS IN THE TRICARBOXYLIC ACID CYCLE Oxidative Decarboxylation of Pyruvate The Intracellular Function of Vitamin Bj... 

The way in which thiamine participated in the oxidation of pyruvate became clearer when Lohmann and Schuster (1937) showed vitamin Bj to be present intracellularly as thiamine pyrophosphate. In yeast, decarboxylation of pyruvate yielded ethanal which was reduced by alcohol dehydrogenase to give ethanol. A cofactor was needed for this decarboxylation, co-carboxylase. Like the cofactor needed in animal cells for the decarboxylation of pyruvate, cocarboxylase was found to be identical to thiamine pyrophosphate. Vitamin Bj thus became the first vitamin whose intracellular function as a coenzyme had been established in vitro. Another aphorism therefore arose about vitamins—B vitamins are (parts of) coenzymes—an idea that was to be completely confirmed. 

Peters showed vitamin Bj required for the oxidation of pyruvate in vitro. 

The SP procedure of water-soluble vitamins from multivitamin tablets is particularly challenging due to the diverse analytes of varied hydrophobicities and pfC. Water-soluble vitamins (WSVs) include ascorbic acid (vitamin C), niacin, niacinamide, pyridoxine (vitamin B ), thiamine (vitamin Bj), folic acid, riboflavin (vitamin B2) and others. While most WSVs are highly water soluble, riboflavin is quite hydrophobic and insoluble in water. Folic acid is acidic while pyridoxine and thiamine are basic. In addition, ascorbic acid is light sensitive and easily oxidized. The extraction strategy employed was a two-step approach using mixed solvents of different polarity and acidity as follows ... 

Answer D. Sideroblastic anemia in a person being treated for tuberculosis (with isoni-azid) is most likely due to vitamin deficiency. 6-Aminolevulinate synthase, the first enzyme in heme synthesis requires vitamin Bj (pyridoxine). 

Delirium tremens (the D.T.s ) resulting from alcohol withdrawal is slightly different in that it is usually preceded by the shakes, convulsions and occasionally by alcoholic hallucinosis - characterized by accusatory auditory hallucinations. As observed 60 years ago by Maurice Victor, an expert on alcohol problems, delirium tremens usually does not appear until day 3 or 4 following abrupt withdrawal from alcohol. The patient is generally malnourished and grossly deficient in vitamin Bj (thiamine) as the result of a diet consisting of little but alcohol. This deficiency ftirther compromises mental function. 

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