Vitamin pyridoxine

With the exception of glycogen phosphorylase (Chapter 15), and kynureninase, all of the pyridoxine-requiring 

Structures of the three naturally occurring compounds having vitamin B6 activity. 

Vitamin Bg status can be evaluated by direct measurement of plasma pyridoxine or pyridoxal phosphate by microbiological, enzymatic, radioimmunological, or chemical methods. Measurement of urinary xanthurenic acid or other intermediates of the kynurenine pathway (Chapter 17) are used to assess indirectly the adequacy of vitamin Bg for metabolic needs. 

Vitamin Bg is rapidly absorbed from the intestine by passive diffusion. Phosphorylated pyridoxine vitamers are 

Metabolism of pyridoxine-related compounds in mammals. Enzymes 1, pyridoxal kinase (present in all mammalian tissues) 2, nonspecific (probably alkaline) phosphatases 3, pyridoxine oxidase (cofactor is FMN O2 is required subject to product inhibition) 4, aldehyde oxidase or aldehyde dehydrogenase 5, aminotransferase, 

The major sales form of vitamin B6 is the hydrochlorid salt of the primary alcohol pyridoxine. Another vitamin B6 form introduced in the market is the dihydrochlo-rid salt of pyridoxamine. Both vitamin B6 forms are commercially produced via various straightforward chemical synthesis routes. The biologically active cofactor is the aldehyde pyridoxal-5 -phosphate, which is derived in human or animals from the vitamin B6 forms by oxidation or transamination before or after 5 phosphorylation by pyridoxal kinases. 

In accordance with the idea of a strongly repressed enzyme, the in vitro activity oiB. subtilis Pdxl is extremely low = 0.018 mm ). A rough estimate based on 

The best pyridoxine production process reported so far is based on the a-proteobacterium S. meliloti IF014782, a natural pyridoxine overproducer. A derivative of IF014782 obtained by classical mutagenesis and overexpressing PdxJ and Epd provided 1.3 gl pyridoxine [348], which is still too low to beat the chemical processes. 

Many of today s industrial enzymes are produced hy Bacillus species, especially B. subtilis, B. amyloliquefaciens, and B. licheniformis. These include amylases. 

ZP and JMvD were supported by the CEU BaSynthec project 244093. LK and JMvD were supported by the transnational SysMO initiative through projects BACELL SysMOl and 2 with funding from the Research Council for Earth and Life Sciences of the Netherlands Organization for Scientific Research (NWO-ALW). 

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Uses. Butanediol is used to manufacture the insecticide Endosulfan, other agricultural chemicals, and pyridoxine (vitamin B ) (see Vitamins) (116). Small amounts are consumed as a diol by the polymer industry. 

Most amino acids lose their nitrogen atom by a transamination reaction in which the -NH2 group of the amino acid changes places with the keto group of ct-ketoglutarate. The products are a new a-keto acid plus glutamate. The overall process occurs in two parts, is catalyzed by aminotransferase enzymes, and involves participation of the coenzyme pyridoxal phosphate (PLP), a derivative of pyridoxine (vitamin UJ. Different aminotransferases differ in their specificity for amino acids, but the mechanism remains the same. 

Isoniazid Take this drug 1 hour before or 2 hours after meals. However, if gastric upset occurs, take isoniazid with food. Notify the primary health care provider of weakness, yellowing of the skin, loss of appetite, darkening of the urine, skin rashes, or numbness or tingling of the hands or feet. Avoid tyrainine-containing foods (see Chap. 31). To prevent pyridoxine (vitamin Bg) deficiency, 6 to 50 mg of pyridoxine daily may be prescribed. 

Levodopa interacts with many different drugs. When levodopa is used with phenytoin, reserpine, and papaverine, there is a decrease in response to levodopa The risk of a hypertensive crisis increases when levodopa is used with the monoamine oxidase inhibitors (see Chap. 31). Foods high in pyridoxine (vitamin B6) or vitamin B6 preparations reverse the effect of levodopa However, when carbidopa is used with levodopa, pyridoxine has no effect on the action of levodopa hi fact, when levodopa and carbidopa are given together, pyridoxine may be prescribed to decrease the adverse effects associated with levodopa... 

There is evidence that some people are sensitive to free glutamates. These people get headaches or other symptoms if they ingest too much. This may be related to pyridoxine (vitamin B6) deficiencies, as this vitamin is necessary for glutamate metabolism. People with uncontrolled severe asthma may find that glutamates complicate or worsen their symptoms. 

Brousmiche, D. W. Wan, P. Photogeneration of an o-quinone methide from pyridoxine (vitamin B6) in aqueous solution. J. Chem. Soc., Chem. Commun. 1998, 491 -92. 

Nonpharmacologic therapy such as dietary, physical, and behavioral approaches should be considered first. Pyridoxine (vitamin B6) 10 to 25 mg three to four times daily alone or in combination with an antihistamine such as doxylamine is often used for NVP.9,11,12 This combination was previously marketed as Bendectin or Debendox but was withdrawn due to concerns over possible teratogenic effects, although the literature did not support this claim.11,12 Pyridoxine is well tolerated, but doxylamine and other antihistamines commonly cause drowsiness. For more severe NVP, promethazine, meto-clopramide, and trimethobenzamide may be effective and have not been associated with teratogenic effects.9... 

The transsulfuration pathway is the major route for the metabolism of the sulfur-containing amino adds 674 Homocystinuria is the result of the congenital absence of cystathionine synthase, a key enzyme of the transsulfuration pathway 676 Homocystinuria can be treated in some cases by the administration of pyridoxine (vitamin B6), which is a cofactor for the cystathionine synthase reaction 676... 

Homocystinuria can be treated in some cases by the administration of pyridoxine (vitamin Bs), which is a cofactor for the cystathionine synthase reaction. Some patients respond to the administration of pharmacological doses of pyridoxine (25-100 mg daily) with a reduction of plasma homocysteine and methionine. Pyridoxine responsiveness appears to be hereditary, with sibs tending to show a concordant pattern and a milder clinical syndrome. Pyridoxine sensitivity can be documented by enzyme assay in skin fibroblasts. The precise biochemical mechanism of the pyridoxine effect is not well understood but it may not reflect a mutation resulting in diminished affinity of the enzyme for cofactor, because even high concentrations of pyridoxal phosphate do not restore mutant enzyme activity to a control level. 

Pyridoxine (vitamin B-6,274) was irradiated in neutral solution in the presence of oxygen at 254 nm to give the diacid (275). It was possible to identify all partial and fully oxidized intermediates to (275) at both the 4- and 5-positions. When the irradiation was performed in the absence of oxygen, only the dimer (277) was obtained [170],... 

Group-transfer reactions often involve vitamins3, which humans need to have in then-diet, since we are incapable of realizing their synthesis. These include nicotinamide (derived from the vitamin nicotinic acid) and riboflavin (vitamin B2) derivatives, required for electron transfer reactions, biotin for the transfer of C02, pantothenate for acyl group transfer, thiamine (vitamin as thiamine pyrophosphate) for transfer of aldehyde groups and folic acid (as tetrahydrofolate) for exchange of one-carbon fragments. Lipoic acid (not a vitamin) is both an acyl and an electron carrier. In addition, vitamins such as pyridoxine (vitamin B6, as pyridoxal phosphate), vitamin B12 and vitamin C (ascorbic acid) participate as cofactors in an important number of metabolic reactions. 

The last of the B vitamins to be identified in the water-soluble vitamin complex from milk was pyridoxine, vitamin B6 (Birch and Gyorgy, 1936). This was needed to prevent a type of dermatitis in rats which was different from pellagra or acrodynia and could be accompanied by convulsions. Much of the early work on the mode of action of this vitamin came from experiments on microbial metabolism (Chapter 6). 

Not all vitamin coenzymes need to be in the form of a nucleotide (base, sugar, phosphate). For example thiamine biotin pyridoxine vitamin B12. 

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 ... 

ALA synthase, the rate-limiting enzyme, requires pyridoxine (vitamin B ). Deficiency of pyri-doxine is associated with isoniazid therapy for tuberculosis and may cause sideroblastic anemia with ringed sideroblasts. 

After decontamination by emesis or lavage, patients should be carefully monitored for alterations in liver and kidney function, and treated symptomatically if necesseray. Seizures can be treated with anti-convulsant drugs. Because the toxin produces a deficiency of y-amino-butyric acid (GABA), specific treatment with pyridoxine (vitamin Bg) has been recommended. 

Protriptyline (Vivactil) Antidepressant Pyrazinamide (PZA) T uberculostatic Pyridoxine (Vitamin Vitamin B6)... 

Administer pyridoxine (vitamin Be) 25 to 50 mg daily or 50 to 100 mg twice weekly to all HIV-infected patients who are undergoing tuberculosis treatment with isoniazid to reduce the occurrence of isoniazid-induced side effects in the central and peripheral nervous system. 

Pyridoxine (vitamin 65) deficiency sometimes is observed in adults taking high doses of INH and is probably caused by the drug s competition with pyridoxal phosphate for the enzyme apotryptophanase. 

Do not use rifapentine alone. Concomitant administration of pyridoxine (vitamin 65)... 

K-Lor, Slow-K, Micro-K, Klorvess, others) (Table VI-5) Pyridoxine [Vitamin B ] Thiamine [Vitamin BJ... 

Pyridoxine [Vitamin B ] [Vitamin B Supplement] U e Rx prevention of vit B6 deficiency Action Vit supl Dose Adults. Deficiency 10-20 mg/d PO Drug-induced neuritis 100-200 mg/d 25-100 mg/d prophylaxis Peds. 5-25 mg/d x 3 wk Caution [A (C if doses exceed RDA), +] Contra Component aUCTgy Disp Tabs 25, 50, 100 mg inj 100 mg/mL SE Allergic Rxns, HA, N Interactions -1- Effects OF levodopa, phenobarbital, phenytoin EMS Can be used as an antidote for isoniazid poisoning OD May cause sensory nerve damage (numbness, tingling, reduced sensation) and coordination problems Sxs are usually revised aft stopping pyridoxine symptomatic and supportive... 

Pyridoxine (vitamin Bg, 18) (Fig. 13) assists in the balancing of sodium and potassium as well as promoting red blood cell production. A lack of pyridoxine can cause anemia, nerve damage, seizures, skin problems, and sores in the mouth. It is required for the production of the monoamine neurotransmitters serotonin, dopamine, norepinephrine, and epinephrine, as it is the precursor to pyridoxal phosphate, which is the cofactor for the aromatic amino acid decarboxylase enzyme. 

CNS toxicity occurs because isoniazid has structural similarities to pyridoxine (vitamin Be) and can inhibit its actions. This toxicity is dose-related and more common in slow acetylators. Manifestations include peripheral neuropathy, optic neuritis, ataxia, psychosis and seizures. The administration of pyridoxine to patients receiving INH does not interfere with the tuberculostatic action of INH but it prevents and can even reverse neuritis. Hematological effects include anaemia which is also responsive to pyridoxine. In some 20% of patients antinuclear antibodies can be detected but only in a minority of these patients drug-induced lupus erythematosus becomes manifest. 

Pyridoxine (vitamin Be) is essential for protein metabolism and plays an important role in hemoglobin production. Pyridoxamine and pyri-doxal also possess vitamin Be activity. Sources of... 

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