-
Toxicology and Applied Pharmacology May 1978
Topics: Animals; Body Weight; Dogs; Eating; Female; Pyridoxine; Spinal Cord; Time Factors
PubMed: 675705
DOI: 10.1016/0041-008x(78)90194-1 -
The Analyst May 1987
Topics: Indicators and Reagents; Pyridoxine; Spectrophotometry, Ultraviolet
PubMed: 3605627
DOI: 10.1039/an9871200653 -
Biochimica Et Biophysica Acta May 1995The origin of the nitrogen atom of pyridoxine was studied in Saccharomyces cerevisiae. The 15N atom of 15NH4Cl added to the growth medium as the nitrogen source was...
The origin of the nitrogen atom of pyridoxine was studied in Saccharomyces cerevisiae. The 15N atom of 15NH4Cl added to the growth medium as the nitrogen source was incorporated efficiently into the nitrogen atom of pyridoxine. The competitive effects of 14N-amino acids on the incorporation of 15NH4Cl were examined. Incorporation of 15N into pyridoxine was inhibited by glutamine. The label of L-[amide-15N]glutamine was incorporated effectively into pyridoxine in S. cerevisiae. On the other hand, the label from L-[amide-15N]glutamine was not incorporated into pyridoxine in Escherichia coli. These findings suggest that the biosynthetic pathway of pyridoxine in S. cerevisiae differs from that in E. coli.
Topics: Escherichia coli; Gas Chromatography-Mass Spectrometry; Glutamine; Nitrogen; Pyridoxine; Saccharomyces cerevisiae
PubMed: 7766645
DOI: 10.1016/0304-4165(94)00205-c -
Bioscience, Biotechnology, and... Mar 2003Microorganisms from culture collections and isolates from nature were screened for the ability to catalyze the regioselective glucosylation of pyridoxine (PN) to produce...
Microorganisms from culture collections and isolates from nature were screened for the ability to catalyze the regioselective glucosylation of pyridoxine (PN) to produce pyridoxine 5'-alpha-D-glucoside (PN-5'-alpha-G) or pyridoxine 4'-alpha-D-glucoside (PN-4'-alpha-G). Transglucosylation activity specific to 5'-position of PN was found in fungi belonging to genera such as Coriolus and Verticillium, and activity at the 4'-position of PN was found in bacteria belonging to genera such as Bacillus and Serratia. From 100 mM PN, intact cells of Verticillium dahliae TPU 4900 produced 42 mM (13.9 mg/mL) PN-5'-alpha-G after 70 h of reaction. Intact cells of Bacillus cereus TPU 5504 produced 33 mM (10.9 mg/mL) PN-4'-alpha-G after 19 h of reaction. The selectivities for 5'- and 4'-positions were 80% and 90%, respectively.
Topics: Bacteria; Catalysis; Fungi; Glucosides; Glycosylation; Microbiological Techniques; Pyridoxine; Stereoisomerism; Temperature; Time Factors
PubMed: 12723596
DOI: 10.1271/bbb.67.499 -
Indian Pediatrics Mar 2005
Topics: Humans; Infant; Male; Pyridoxine; Seizures; Vitamin B 6 Deficiency; Vitamin B Complex
PubMed: 15817985
DOI: No ID Found -
The Journal of Nutrition Apr 1995This study was conducted to characterize the initial time course of the apparent competitive effect of pyridoxine-5'-beta-D-glucoside against co-ingested pyridoxine. Two...
This study was conducted to characterize the initial time course of the apparent competitive effect of pyridoxine-5'-beta-D-glucoside against co-ingested pyridoxine. Two groups of rats were administered a single oral dose of 100 nmol of [14C]pyridoxine along with either 0 or 20 nmol of unlabeled pyridoxine-5'-beta-D-glucoside. At 6, 12, 24 and 48 h post-dose, the distribution of labeled vitamin B-6 metabolites in blood, tissues and urine was determined. Urinary [14C]4-pyridoxic acid comprised a significantly greater percentage of excreted 14C in the control group, with the greatest difference at 12 h post-dose. Pyridoxine-5'-beta-D-glucoside (10-15 nmol) was excreted mainly in unchanged form within 6 h. Rats that received pyridoxine-5'-beta-D-glucoside retained less 14C in liver, with a maximal difference between groups at 6-12 h post-dose. The relative concentrations of hepatic [14C]pyridoxal 5'-phosphate and [14C]pyridoxamine 5'-phosphate in the treatment group were greater than in the control group at approximately 12 h post-dose. At 48 h post-dose, there was no difference in the distribution of any vitamin B-6 metabolite except pyridoxal 5'-phosphate in the two groups. These results confirm that a small, nutritionally relevant dose of pyridoxine-5'-beta-D-glucoside influences the utilization of pyridoxine and indicate that this is a short-term, transient effect.
Topics: Animals; Carbon Radioisotopes; Chromatography, High Pressure Liquid; Diet; Dose-Response Relationship, Drug; Drug Interactions; Glucosides; Kidney; Liver; Male; Pyridoxine; Random Allocation; Rats; Rats, Sprague-Dawley; Time Factors; Tissue Distribution
PubMed: 7722696
DOI: 10.1093/jn/125.4.926 -
Lakartidningen Oct 1972
Topics: Adult; Aged; Child; Diet; Female; Food; Food, Fortified; Humans; Infant Food; Infant Nutritional Physiological Phenomena; Infant, Newborn; Male; Maternal-Fetal Exchange; Neurologic Manifestations; Nutritional Physiological Phenomena; Nutritional Requirements; Pregnancy; Pyridoxine; Vitamin B 6 Deficiency
PubMed: 4643072
DOI: No ID Found -
The Journal of Nutrition Apr 2004An important dietary source of vitamin B-6, pyridoxine-5'-beta-D-glucoside (PNG), exhibits only partial bioavailability, which is limited by the extent of enzymatic...
An important dietary source of vitamin B-6, pyridoxine-5'-beta-D-glucoside (PNG), exhibits only partial bioavailability, which is limited by the extent of enzymatic cleavage of the beta-glucosidic bond to release metabolically available pyridoxine (PN). This laboratory showed that the intestinal hydrolysis of PNG is catalyzed by cytosolic PNG hydrolase (PNGH) and brush border lactase-phlorizin hydrolase (LPH). LPH-catalyzed PNG hydrolysis in vitro is competitively inhibited by lactose. In the present study, the uptake and hydrolysis of PNG were examined in Caco-2 human colon carcinoma cells, which express a functional LPH but exhibit no PNGH activity. PNG uptake at 37 degrees C was linear over 5-500 micromol/L PNG. Uptake was not significantly reduced when Na(+) was substituted with K(+), Li(+), or Tris in the medium. Increasing PNG concentration in the medium did not change intracellular concentrations of PN, pyridoxamine (PM), pyridoxamine 5'-phosphate (PMP), or pyridoxal 5'-phosphate (PLP); however, intracellular pyridoxal (PL) concentration increased. Intracellular PNG concentration was not significantly reduced in the presence of lactose, but the concentration of PL declined in proportion to extracellular lactose (P = 0.01). These results indicate that PNG can be absorbed intact in a Na(+)-independent process and is taken up by passive diffusion. The presence of lactose in this in vitro model of intestinal uptake reduced the enzymatic hydrolysis of PNG by lactase.
Topics: Caco-2 Cells; Glucosides; Humans; Hydrolysis; Kinetics; Lactase; Lactose; Pyridoxal; Pyridoxine; Sodium
PubMed: 15051835
DOI: 10.1093/jn/134.4.842 -
European Journal of Clinical Nutrition May 1989The principal metabolic function of vitamin B6 is in amino acid metabolism, although the greater part of the body's vitamin B6 is in muscle, associated with glycogen... (Review)
Review
The principal metabolic function of vitamin B6 is in amino acid metabolism, although the greater part of the body's vitamin B6 is in muscle, associated with glycogen phosphorylase, and the vitamin also has an important role in the actions of steroid hormones. It is usual to calculate vitamin B6 requirements relative to protein intake. An adequate intake to meet the requirements of virtually the whole population is generally considered to be 15 micrograms/g dietary protein. This is the basis of RDAs in most countries, although differences of interpretation and application of the experimental data result in widely differing recommendations from different authorities. Current RDAs range between 1.5 and 2.2 mg/d. A minimum safe intake, below which an individual would have a high probability of deficiency, is 11 micrograms/g dietary protein. Higher intakes are required in pregnancy and lactation (although there are problems in determining the requirement of the infant), and possibly also in the elderly. Average intakes of vitamin B6 in developed countries meet the target of 15 micrograms/g dietary protein, although there is biochemical evidence of inadequate vitamin B6 nutritional status in 10-25 per cent of the population. It is not know whether this has any clinical significance; it is unlikely that normal patterns of food intake would permit a significantly greater average intake of the vitamins without fortification or the use of supplements. There is little evidence that pharmacological doses of vitamin B6 have any beneficial effect. Neurological damage has been reported at extremely high intakes (in excess of 500 mg/d), and even more modest doses (50-100 mg/d) cannot be regarded as being without hazard.
Topics: Adolescent; Aged; Animals; Female; Humans; Infant; Nutritional Requirements; Nutritional Status; Pregnancy; Pyridoxine; Vitamin B 6 Deficiency
PubMed: 2661220
DOI: No ID Found -
Federation Proceedings Dec 1979
Topics: Animals; History of Medicine; Humans; Pyridoxine; Rats; United States; Vitamin B 6 Deficiency; Xanthurenates
PubMed: 389671
DOI: No ID Found