Vitamin C
Vitamin
Overview
- Vitamin C (ascorbic acid) is a water-soluble micronutrient.
- It functions primarily as a potent antioxidant and a vital co-factor for several enzymatic reactions.
- In humans, it is essential for collagen synthesis, neurotransmitter production, and the regeneration of other antioxidants.
- Vitamin C supports tissue integrity and oxidative balance.
Chemistry
- Vitamin C is chemically known as L-ascorbic acid, with the IUPAC name (5R)-[(1S)-1,2-dihydroxy-3-(4-hydroxy-5-oxo-2-hydroxy-4-pyrrolidyl)-4-hydroxy-5-(hydroxymethyl)-tetrahydrofuran-2-yl]-2-oxy-1-[2-hydroxy-2-oxo-1-(hydroxymethyl)-ethyl]-2-pyrrolidine-1-carboxylic acid.
- Its molecular formula is C₆H₈O₆, with a molar mass of 176.12 g mol⁻¹.
- The molecule features a six-membered lactone ring (a γ-lactone) bearing a 2-keto-L-guloside skeleton with an enediol (C2–C3) double bond that confers its strong reducing capacity.
- The molecule is highly water-soluble (≈330 g/L at 25 °C) and displays a pKa of ~4.2, making it predominantly ionized (ascorbate) at physiological pH.
- The stereochemistry (L-configuration) is essential for enzymatic recognition; the D-isomer (D-ascorbic acid) is biologically inactive.
Sources & Quality
- Commercial vitamin C is principally obtained from two sources:
- Natural extraction from citrus fruits, kiwi, and berries
- Industrial synthesis via the Reichstein or modern biotechnological fermentation pathways
- The Reichstein process converts glucose to 2-keto-L-gulonic acid, then to ascorbic acid through a series of oxidation, lactonization, and stereospecific steps, yielding a highly pure (>99 %) product.
- Fermentative production uses genetically engineered Gluconobacter or Pseudomonas strains to directly produce L-ascorbic acid from glucose, offering a “natural-origin” label.
- Quality considerations for supplements include:
- Verifying the absence of heavy metals, pesticide residues
- Confirming the presence of the L-isomer via chiral HPLC
- Certifications such as GMP, USP–NF, or ISO 9001, and third-party testing for purity and potency, are essential for ensuring safety and efficacy.
Where to Buy Vitamin C
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