Vitamin B6 (Pyridoxine)

Vitamin B6, chemically known as pyridoxine, is a water-soluble B-vitamin that functions primarily as a co-enzyme in more than 100 enzymatic reactions. Its most critical role is as a co-factor for enzymes involved in amino-acid metabolism, neurotransmitter synthesis, and the regulation of homocysteine, thereby influencing both metabolic and neurological health.

• Pyridoxine (C₈H₁₁NO₃) has a molecular weight of 169.18 g/mol.
• Its IUPAC name is 4-hydroxy-3-(hydroxymethyl)-2-methylpyridine-5-carboxylic acid.
• The molecule consists of a pyridine ring substituted with a hydroxyl group at position 4, a methyl group at position 2, a hydroxymethyl side chain at position 3, and a carboxyl group at position 5.
• The presence of a hydroxymethyl group and a 4-hydroxyl group makes pyridoxine relatively soluble in water (≈ 120 g/L at 25 °C) and moderately stable to heat and light.
• The active co-enzyme, PL-5′P, is formed by oxidation of the hydroxymethyl group to an aldehyde (pyridoxal) followed by phosphorylation at the 5′-hydroxyl, yielding a highly polar phosphate ester.

• Natural dietary sources include poultry, fish, organ meats, bananas, chickpeas, and fortified cereals.
• Industrially, pyridoxine is produced by chemical synthesis from 2-methyl-4-hydroxy-5-nitro-pyridine via reduction and subsequent hydroxymethylation, yielding a high-purity (>99 %) crystalline powder.
• Fermentation-based production (e.g., Bacillus spp.) is emerging as a “green” alternative.
• For supplements, USP-grade pyridoxine is preferred; manufacturers must verify identity (HPLC), purity (absence of heavy metals), and stability (avoid exposure to light/humidity).
• Standardized “pyridoxine HCl” is the most common form, providing predictable bioavailability, while pyridoxal-5′phosphate (the active form) is offered for individuals with conversion impairments.