Pyridoxine

Pyridoxal phosphate

Vitamin B6 is a water-soluble vitamin. Pyridoxal phosphate (PLP) is the active form and is a cofactor in many reactions of amino acid metabolism, including transamination, deamination, and decarboxylation. PLP also is necessary for the enzymatic reaction governing the release of glucose from glycogen. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Main article: vitamin B6 Pyridoxine is one of the compounds that can be called vitamin B6, along with Pyridoxal and Pyridoxamine. ... Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Pyridoxal-phosphate (PLP, pyridoxal-5-phosphate) is a cofactor of many enzymatic reactions. ... Retinol (one vitamer of Vitamin A) A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. ... A cofactor is any substance that needs to be present in addition to an enzyme to catalyze a certain reaction. ... This article is about the class of chemicals. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... Glycogen Structure Segment Glycogen is a polysaccharide of glucose (Glc) which functions as the primary short term energy storage in animal cells. ...

Forms

Seven forms of this vitamin are known:

• pyridoxine (PN). PN is the form that is given as vitamin B6 supplement.
• pyridoxine 5'-phosphate (PNP).
• pyridoxal (PL).
• pyridoxal 5'-phosphate (PLP). PLP is the metabolically active form.
• pyridoxamine (PM).
• pyridoxamine 5'-phosphate (PMP).
• 4-pyridoxic acid (PA). PA is the catabolite which is excreted in the urine.

All forms except PA can be interconverted. Main article: vitamin B6 Pyridoxine is one of the compounds that can be called vitamin B6, along with Pyridoxal and Pyridoxamine. ... Pyridoxal is one of the three natural organic compounds, along with pyridoxamine and pyridoxine, that comprise vitamin B6. ... Pyridoxal-phosphate (PLP, pyridoxal-5-phosphate) is a cofactor of many enzymatic reactions. ... The two major forms of vitamin B6 are pyridoxine and pyridoxamine. ...

History

Vitamin B6 is a water-soluble compound that was discovered in the 1930s during nutrition studies on rats. The vitamin was named pyridoxine to indicate its structural homology to pyridine. Later it was shown that vitamin B6 could exist in two other, slightly different, chemical forms, termed pyridoxal and pyridoxamine. All three forms of vitamin B6 are precursors of an activated compound known as pyridoxal 5'-phosphate (PLP), which plays a vital role as the cofactor of a large number of essential enzymes in the human body. Pyridine is a chemical compound with the formula C5H5N. It is a liquid with a distinctively putrid odour. ... Pyridoxal-phosphate (PLP, pyridoxal-5-phosphate) is a cofactor of many enzymatic reactions. ...

Enzymes dependent on PLP focus a wide variety of chemical reactions mainly involving amino acids. The reactions carried out by the PLP-dependent enzymes that act on amino acids include transfer of the amino group, decarboxylation, racemization, and beta- or gamma-elimination or replacement. Such versatility arises from the ability of PLP to covalently bind the substrate, and then to act as an electrophilic catalyst, thereby stabilizing different types of carbanionic reaction intermediates.

Overall, the Enzyme Commission (EC; http://www.chem.qmul.ac.uk/iubmb/enzyme/ ) has catalogued more than 140 PLP-dependent activities, corresponding to ~4% of all classified activities.

In the early 1990s, it was suggested in megadoses as treatment for PMS and clinical depression, but this is no longer considered effective. ^[1] Premenstrual stress syndrome Pocahontas Middle School ... On the Threshold of Eternity. ...

Sources

The United States RDA is 1.3 mg both for men and for women of any age, 1.9 mg for women who are pregnant, and 2.0 mg for women who are lactating. Reference Daily Intake (RDI) is the daily dietary intake level of a nutrient considered sufficient to meet the requirements of nearly all (97–98%) healthy individuals in each life-stage and gender group. ...

Dietary sources of vitamin B6 include both animal and vegetable foods. Green and leafy vegetables, meats, fish, poultry, shellfish, legumes, fruits, and whole grains are particularly good sources. (According to Understanding Nutrition Eighth edition - Instructor's edition, p 306, ISBN 0-534-54612-9).

Deficiencies

The classic clinical syndrome for B6 deficiency is a seborrheic dermatitis-like eruption, atrophic glossitis with ulceration, angular cheilitis, conjunctivitis, intertrigo, and neurologic symptoms of somnolence, confusion, and neuropathy.^[2] The classic clinical syndrome for Pyridoxine deficiency (or B6 deficiency) is a seborrheic dermatitis-like eruption, atrophic glossitis with ulceration, angular cheilitis, conjunctivitis, intertrigo, and neurologic symptoms of somnolence, confusion, and neuropathy. ...

Overdose

An overdose of pyridoxine can cause a temporary deadening of certain nerves such as the proprioceptory nerves; causing a feeling of disembodiment common with the loss of proprioception. This condition is reversible when supplementation is stopped.^[3] // Proprioception (PRO-pree-o-SEP-shun (IPA pronunciation: ); from Latin proprius, meaning ones own and perception) is the sense of the relative position of neighbouring parts of the body. ...

Because adverse effects have only been documented from vitamin B6 supplements and never from food sources, this article only discusses the safety of the supplemental form of vitamin B6 (pyridoxine). Although vitamin B6 is a water-soluble vitamin and is excreted in the urine, very high doses of pyridoxine over long periods of time may result in painful neurological symptoms known as sensory neuropathy. Symptoms include pain and numbness of the extremities, and in severe cases difficulty walking. Sensory neuropathy typically develops at doses of pyridoxine in excess of 1,000 mg per day. However, there have been a few case reports of individuals who developed sensory neuropathies at doses of less than 500 mg daily over a period of months. None of the studies, in which an objective neurological examination was performed, found evidence of sensory nerve damage at intakes of pyridoxine below 200 mg/day. In order to prevent sensory neuropathy in virtually all individuals, the Food and Nutrition Board of the Institute of Medicine set the tolerable upper intake level (UL) for pyridoxine at 100 mg/day for adults. Because placebo-controlled studies have generally failed to show therapeutic benefits of high doses of pyridoxine, there is little reason to exceed the UL of 100 mg/day. Studies have shown, however, that in the case of individuals diagnosed with autism, high doses of vitamin B6 given with magnesium have been found to be beneficial.^[4] Neuropathy is usually short for peripheral neuropathy, meaning a disease of the peripheral nervous system. ... General Name, symbol, number magnesium, Mg, 12 Chemical series alkaline earth metals Group, period, block 2, 3, s Appearance silvery white solid at room temp Standard atomic weight 24. ...

Preventive roles and therapeutic uses

At least one preliminary study has found that this vitamin may increase dream vividness or the ability to recall dreams.^[5] It is thought that this effect may be due to the role this vitamin plays in the conversion of tryptophan to serotonin.^[5] For other uses, see Dream (disambiguation). ... Tryptophan (abbreviated as Trp or W)[1] is one of the 20 standard amino acids, which are the building blocks of proteins, and an essential amino acid in the human diet. ... For the professional wrestling stable, see Ravens Nest#Serotonin. ...

The intake of vitamin B6, from either diet or supplements, could cut the risk of Parkinson’s disease by half according to a prospective study from the Netherlands. "Stratified analyses showed that this association was restricted to smokers," wrote the authors.^[6] Parkinsons disease (PD; paralysis agitans) is a neurodegenerative disease of the substantia nigra (an area in the basal ganglia of the brain). ...

Nutritional supplementation with high dose vitamin B6 and magnesium is claimed to alleviate the symptoms of autism and is one of the most popular complementary and alternative medicine choices for autism. Three small randomized controlled trials have studied this therapy; the smallest one (with 8 individuals) found improved verbal IQ in the treatment group and the other two (with 10 and 15 individuals, respectively) found no significant difference. The short-term side effects seem to be mild, but there may be significant long-term side effects of peripheral neuropathy.^[7] Some studies suggest that the B6-magnesium combination can also help attention deficit disorder , citing improvements in hyperactivity, hyperemotivity/aggressiveness and improved school attention. ^[8] A randomized controlled trial (RCT) is a form of clinical trial, or scientific procedure used in the testing of the efficacy of medicines or medical procedures. ... Peripheral neuropathy is the term for damage to nerves of the peripheral nervous system, which may be caused either by diseases of the nerve or from the side-effects of systemic illness. ... DISCLAIMER Please remember that Wikipedia is offered for informational use only. ...

It is also suggested that ingestion of vitamin B6 can alleviate some of the many symptoms of an alcoholic hangover and morning sickness from pregnancy. This might be due to B6's mild diuretic effect.^[9] This illustration shows where some types of diuretics act, and what they do. ...

External links

• Facts about Vitamin B6 from Office of Dietary Supplements at National Institutes of Health
• The B6 database A database of B6-dependent enzymes at University of Parma
• Vitamin B6 Information Sheet from the Linus Pauling Institute at Oregon State University
• Vitamin B6 (and magnesium) in the treatment of autism from the Autism Research Institute
• MeSH Vitamin+B6

National Institutes of Health Building 50 at NIH Clinical Center - Building 10 The National Institutes of Health (NIH) is an agency of the United States Ministry of Health and Human Services and is the primary agency of the United States government responsible for biomedical and health-related research. ... The University of Parma, Italy, (Università degli Studi di Parma) is one of the oldest universities in the world, founded in the 11th century. ... Oregon State University (OSU) is a coeducational, public research university located in Corvallis, Oregon, United States. ... The Autism Research Institute (ARI), established in 1967 by Bernard Rimland, is a San Diego, California, based nonprofit that funds research and provides information on autism and related autistic spectrum disorders. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ...

References