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The Chemistry and Biochemistry of Vitamin B6: Synthesis of Novel Analogues of Vitamin B6

This chapter focuses on vitamin B6. Vitamin B6 exists in three basic chemical forms: pyridoxine (an alcohol), pyridoxal (an aldehyde) and pyridoxamine (a primary amine). The three major forms can be phosphorylated at the 5-hydroxymethyl group. Vitamin B6 is an essential participant in numerous metabolic processes and has a role as a cofactor in enzyme-catalysed reactions. The first total synthesis of vitamin B6 was obtained by the condensation of acetylacetone and cyanacetamide. Alternative methods for the synthesis of pyridoxine analogues have been described, which include Diels–Alder reactions of substituted oxazoles. All living beings need vitamin B6 for their existence. However, only microorganisms and plants are able to synthesize it de novo. Two independent de novo biosynthetic routes are known. Vitamin B6 is essential for more than 100 enzymes involved in protein metabolism. Pyridoxal- 5-phosphate is covalently bound to enzymes via a Schiff’s base with an e-amino group of lysine in the enzyme. PLP-dependent enzymes are involved in important steps of amino acid metabolism, hemoglobin formation and chlorophyll biosynthesis. Vitamin B6 could have a role in preventing oxidative stress of the cells and is an impotent quencher of singlet oxygen. A deficiency of vitamin B6 in the human diet encompasses the full spectrum of clinical disorders such as hyperhomocysteinaemia and increases the risk for atherosclerosis. It has been shown that vitamin B6 can interact with DNA.

vitamin B6 ; chemistry ; function ; novel analogues

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