Pyridoxine
Overview
Pyridoxine (peer-ih-DOCK-seen) is also known as 3-Hydroxy-4,5-bis(hydroxymethyl)-2-methylpyridine; 3-hydroxy-4,5-dimethylol-2-methylpyridine; and vitamin B6. It is a white, odorless, crystalline compound with a slightly bitter taste. The term pyridoxine is also used as a generic term for three compounds with biological activity classified under the term Vitamin B6. The three compounds are pyridoxine, pyridoxal, and pyridoxamine. Pyridoxine is usually produced commercially as the hydrochloride, CH3C5HN(OH)(CH2OH)2·;HCl, which has somewhat different physical characteristics from pyridoxine itself.
Key Facts
Other Names:
See Overview.
Formula:
CH3C5HN(OH)(-CH2OH)2
Elements:
Carbon, hydrogen, nitrogen, oxygen
Compound Type:
Organic
State:
Solid
Molecular Weight:
169.18 g/mol
Melting Point:
159°C-162°C (318°F-324°F)
Boiling Point:
Not applicable; sublimes above melting point
Solubility:
Very soluble in water; slightly soluble in ethyl alcohol and acetone
Vitamin B6 was discovered in 1938 by five groups of researchers working independently. The five groups were all looking for a cure for a disease in rats called acrodynia that resembles the human disease pellagra. In the early 1930s, the Hungarian-American biochemist Albert Szent-Györgi (1893–1986) hypothesized the existence of a vitamin that would cure acryodynia and even gave the vitamin a name, vitamin B6. So the simultaneous discovery of such a compound in 1938 was not much of a surprise.
The first component of vitamin B6, pyridoxine, was first synthesized, also in 1938, by the Austrian-German chemist Richard Kuhn (1900–1967). Its chemical structure was determined a year later by American chemists Karl August Folkers (1906–1997) and S. A. Harris (dates not available) at the Merck chemical corporation. Pyridoxine is the most stable form of the vitamin, so it is the form used in vitamin supplements and as a food additive.
How It Is Made
Pyridoxine is produced naturally by most plants and animals in sufficient amounts to prevent vitamin B6 deficiency diseases. It is also produced synthetically by a complex series of reactions that begins with isoquinoline (C9H7N).
Common Uses and Potential Hazards
Vitamin B6 has been shown to be essential in many biochemical reactions that occur in plants and animals. Although it may occur in any one of the three forms listed above, the compound usually acts as the phosphate ester, pyridoxine phosphate. Pyridoxine phosphate functions as a coenzyme in the transformation of amino acids, the building blocks from which proteins are made. A coenzyme is a chemical compound that works with an enzyme to catalyze some essential chemical reaction in the body. Pyridoxine phosphate appears to be necessary for the synthesis of proteins from amino acids as well as the metabolism of amino acids to produce energy needed for normal body functioning.
Interesting Facts
Because pyridoxine is water soluble, it dissolves when foods are cooked or processed.
Vitamin B6 deficiency diseases are very rare. In 1954, a batch of commercially prepared baby food was overheated during its preparation. Overheating apparently destroyed the vitamin B6 present in the food. Babies who were fed with the food had convulsions became unusually irritable, and developed unusual behaviors. As soon as the babies were given vitamin B6 supplements, these symptoms disappeared. Such instances among humans are so rare that they become the subject of articles in medical journals. Other reported instances of vitamin B6 deficiency disease have involved pregnant women who did not receive enough of the vitamin in their daily diets and people living in Cuba during the early 1990s who had restricted diets. Symptoms of vitamin B6 deficiency include general weakness, anemia, cracked lips, inflamed tongue and mouth, irritability, depression, and skin disorders.
Meats have the highest concentration of vitamin B6, so vegetarians may be at risk for deficiency disorders. Other foods that contain high concentrations of the vitamin include bananas, mangoes, avocados, and potatoes. Increased doses of vitamin B6 are sometimes used to treat morning sickness and insomnia, and some authorities recommend the vitamin to decrease the risk of heart disease. The maximum recommended dose of vitamin B6 is 50 milligrams a day.
Words to Know
A material that increases the rate of a chemical reaction without undergoing any change in its own chemical structure. The process including all of the chemical reactions that occur in cells by which fats, carbohydrates, and other compounds are broken down to produce energy and the compounds needed to build new cells and tissues. Chemical reaction in which some desired chemical product is made from simple beginning chemicals, or reactants.For Further Information
Brody, Tom. Nutritional Biochemistry. San Diego: Academic Press, 1998.
"Dietary Supplement Fact Sheet: Vitamin B6." NIH Office of Dietary Supplements. http://ods.od.nih.gov/factsheets/vitaminb6.asp (accessed on November 3, 2005).
Turner, Judith. "Pyridoxine." In Gale Encyclopedia of Alternative Medicine. Detroit: Gale Group, 2004.
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