Vitamin B6(pyridoxine)

Vitamin B6, also commonly called pyridoxine, is an essential water-soluble vitamin used as a cofactor in a number of enzymatic reactions. Vitamin B6 in the diet is found as pyridoxine, pyridoxal, and pyridoxamine all of which are hydrolysed by a phosphatase before absorption across the intestinal mucosa by passive diffusion. Once within the enterocyte the hydrolysed vitamin B6 derivative is phosphorylated by pyridoxine kinase and transported to the liver for continued metabolism to its active form, pyridoxal-5-phosphate (PLP). In the liver PLP is bound to albumin and then transported to target tissues. Large concentrations of pyridoxine are found in muscle, but this depot is not available during periods of Vitamin B6 deficiency and is only released during muscle catabolism. Vitamin B6 derivatives are freely filtered by the renal tubules. The active form of Vitamin B6, PLP, participates in a number of reactions involving amino acid metabolism (e.g. aminotransferases, decarboxylases, racemizations) as well as various synthetic pathways and gluconeogenesis.