Pyridoxine pyridoxol, vitamin

Pyridoxine (pyridoxol), pyridoxamine, and pyridoxal are the three natural forms of vitamin Bg. They are converted to pyridoxal phosphate, which is required for the synthesis, catabohsm, and interconversion of amino acids. 

The vitamin Bg group comprises three natural forms pyridoxine (pyridoxol) (PA/), pyridoxamine (PM), and pyridoxal (PL), which are 4-substituted 2-methyl-3-hydroxyl-5-hydroxymethyl pyridines (Figure 30-13). During metabolic conversions, each vitamer becomes phosphorylated at the 5-hydroxymethyl substituent. Although both pyridox-amine-5 -phosphate (PMP) and pyridoxal-S -phosphate (PLP, P-5 -P) interconvert as coenzyme forms during aminotransferase (transaminase)-catalyzed reactions, PLP is the coenzyme form that participates in the large number of Bg-dependent enzyme reactions. 

Nomenclature. Pyridoxine (vitamin Bg) group name for pyridoxine (pyridoxol), pyridoxal, pyridoxamine and the 5 -phosphorylated derivatives of these compounds. 

The term vitamin Bg refers to a group of naturally occurring pyridine derivatives represented by pyridoxine (pyridoxol, PN), pyridoxal (PL), and pyridoxamine (PM), and their phosphorylated derivatives. They are collectively referred to as vitamin Bg vitamers. The natural free forms of the vitamers could be converted to the key coenzymatic form, pyridoxal phosphate (PLP), by the action of two enzymes, a kinase and an oxidase. There are more than 140 PLP-dependent enzymatic reactions, and they are distributed in all organisms. These enzymes comprise diverse groups such as the oxidoreductases, transferases, hydrolases, lyases, and isomerases. About... 

Vitamin Bg is a mixture of six interrelated forms pyridoxine (or pyridoxol) (Figure 19.23), pyri-doxal, pyridoxamine, and their 5 -phosphates derivatives. Interconversion is possible between all forms. The active form of the vitamin is pyridoxal phosphate, which is a coenzyme correlated with the function of more than 60 enzymes involved in transamination, deamination, decarboxylation, or desulfuration reactions. 

VITAMIN B (Pyridoxine). Infrequently called adermine or pyridoxol, this vitamin participates in protein, carbohydrate, and lipid metabolism. The metabolically active form of B6 is pyridoxal phosphate, the structures of which are ... 

Piridoxina hydrochloride Pyridoxine hydrochloride Pyridoxinium chloride Pyridoxol hydrochloride Vitamin B6 hydrochloride... 

The generic descriptor vitamin Be includes six vittuners the alcohol pyridox-ine, the tildehyde pyridoxal, the amine pyridoxcunine, tmd their 5 -phosphates. There is some confusion in the older literature, because at one time pyridoxine was used as a generic descriptor, with pyridoxol tis the specific ntune for the alcohol. As shown in Figure 9.1, the vitamers are metaboUccdly interconvertible and, as ftu as is known, they have equtd biologiccil activity. 

Vitamin B Three substances are classed under the term pyridoxine or adermine pyridoxol, pyridoxal and pyridoxamine. Pyridoxine was isolated by various study groups in 1938. Its structure was described by Folkers and Kuhn in 1939. Pyridoxal and pyridoxamine were discovered by Snell in 1942. Pyridoxal phosphate and pyridoxamine phosphate are biologically active substances. Intestinal absorption of Bg is dose-dependent and not limited. In alcoholism, a deficiency of vitamin Bg is encountered in 20—30% of cases, whereas the respective percentage is 50—70% in alcoholic cirrhosis. Vitamin Bg is an important coenzyme for transaminases, which transfer amino groups from amino adds to keto acids. In this way, biochemical pathways between the dtiic acid cycle and carbohydrate and amino acid metabolisms are created. (104)... 

Pyridoxine is available from whole-grain cereals, peanuts, com, meat, poultry, and fish. Up to 40% of the vitamin may be destroyed, however, during cooking. Food sources contain all three forms, cither in their free form or phosphory-lated. Plants contain primarily pyridoxol and pyridoxaminc, while animal sources provide chiefly pyridoxal. Many plants also contain a glycoside of pyridoxol. which is included in vitamin content determinations. Although this conjugate is absorbed, it is not u.sed well. This may explain the lower bioavailability of the vitamin from plant sources than from animal sources. 

Vitamin Bg and Related Compounds.—Analogues of pyridoxol and pyridoxal phosphates in which the 5 -methylene (35) or the 5 -phosphate group (36) have been modified have been used to study the substrate specificity of pyridoxine phosphate oxidase. The methylene analogues acted as substrates whereas (36) or the 2-cyanoethyl ester of pyridoxol... 

Pyridoxol 210 (pyridoxine, 3-hydroxy-4,5-bis(hydroxymethyl)-2-methylpyridine, vitamin B6) was formerly known as adermine (Kuhn 1938) because vitamin B5 deficiency causes skin diseases in animals. Pyridoxal (211, R = CHO) and pyridoxamine (211, R = CH2NH2) also belong to the vitamin B group. Pyridoxal phosphate 212 is a coenzyme for many of the enzymes involved in the metabolism of amino acids. Nicotinamide adenine dinucleotide 213 (NAD , reduced form NADH) is a component of oxidoreductases (for its action see p 293, synthesis see p 131). 

CAS 58-56-0 EINECS/ELINCS 200-386-2 Synonyms Adermine hydrochloride 3-Hydroxy-4,5-dihydroxymethyl-2-methylpyridine HCI 3-Hydroxy-4,5-dimethylol-a-picoline hydrochloride 5-Hydroxy-6-methyl-3,4-pyridinedicarbinol hydrochloride 5-Hydroxy-6-methyl-3,4-pyridinedimethanol hydrochloride 2-Methyl-3-hydroxy-4,5-bis (hydroxymethyl) pyridine hydrochloride Pyridoxine hydrochloride Pyridoxinium chloride Pyridoxinum hydrochloride Pyridoxol hydrochloride Vitamin Be hydrochloride Classification Substituted aromatic compd. Empirical CsHnNOs CIH Properties Colorless to wh. platelets or cryst. powd., odorless sol. in water, alcohol, acetone, propylene glycol si. sol. in other org. soivs. insol. in ether, chloroform m.w. 205.66 m.p. 204-206 C (dec.) pH 2.0-3.5 (5% aq.)... 

An additional poly-substituted pyridine derivative is pyridoxol (pyridoxine/ vitamin Be), which can be made, according to the classical method by Stanton... 

Vitamin Bg (pyridoxine also known as pyridoxol, 118) is an essential growth factor in the diet of many organisms and animals. It forms part of a coenzyme (pyridoxylphosphate) and it is a cofactor for a class of enzymes known as transaminases. A transaminase or an aminotransferase is an enzyme that catalyzes a type of reaction between an amino acid and an a-keto acid. The presence of elevated transaminase levels can be an indicator of liver damage. Vitamin Bg has both an aldehyde form (pyridoxal, 119) and an amine form (pyridoxamine, 120), and it is known that pyridoxal phosphate is a carrier of amino groups and sometimes amino acids. ... 

Vitamin B6 activity is exhibited by pyridoxine (Formula 6.11) or pyridoxol (R = CH2OH), pyridoxal (R = CHO) and pyridoxamine (R = CH2NH2). The metabolically active form. 

Synonyms Adermine hydrochloride 3-Hydroxy4,5-dihydroxymelhyl-2-methylpyri-dine HCI 3-Hydroxy4,5-dimelhylol-a-picoline hydrochloride 5-Hydroxy-6-methyl-3,4-pyridinedicarbinol hydrochloride 5-Hydroxy-6-melhyl-3,4-pyridinedimelhanol hydrochloride 2-Methyl-3-hydroxy4,5-bis (hydroxymethyl) pyridine hydrochloride Pyridoxine hydrochloride Pyridoxinium chloride Pyridoxi-num hydrochloride Pyridoxol hydrochloride Vitamin Bg hydrochloride Classification Substituted aromatic compd. 

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