Vitamin D2 (Ergocalciferol)
Vitamins
Overview
- Vitamin D₂ (ergocalciferol) is a fat-soluble secosteroid derived from ergosterol, the fungal analogue of cholesterol.
- In humans, it serves as a pro-hormone that, after hepatic and renal hydroxylation, becomes the active hormone 1,25-dihydroxy-vitamin D (calcitriol).
- Calcitriol binds the vitamin D receptor (VDR) to regulate calcium-phosphate metabolism and influence numerous extra-skeletal processes.
Chemistry
- Molecular Formula: C₂₈H₄₄O
- IUPAC Name: (5Z,7E)-9,10-sec-cholesta-5,7,10-trien-3β-ol
- Structure: Features a broken B-ring (secosteroid) with a double bond at C5-C6 (Z) and C7-C8 (E), and a conjugated diene (C10-C19) plus a hydroxyl group at C3 (β-orientation).
- Lipophilicity: Highly lipophilic (log P ≈ 7.5).
- Melting Point: Near 70 °C.
- Solubility: Soluble in non-polar solvents (e.g., ethanol, olive oil).
- Enzymatic Hydroxylation: The presence of a 3-β-hydroxyl group enables enzymatic hydroxylation to 25-OH-D₂ in the liver.
- VDR Binding Affinity: The stereochemistry at C3 and the conjugated triene system are critical for VDR binding affinity.
Sources & Quality
- Natural Production: Vitamin D₂ is naturally produced by UV-B irradiation of ergosterol in fungi and yeast (e.g., Saccharomyces cerevisiae, Candida spp.).
- Commercial Extraction: Commercially extracted from irradiated mushroom (e.g., Agaricus bisporus).
- Microbial Fermentation: Produced via microbial fermentation of Saccharomyces cultures.
- Purification: Followed by purification through crystallization or high-performance liquid chromatography.
- Synthetic Routes: Synthetic routes exist that chemically convert ergosterol into ergocalciferol using photochemical or chemical oxidation.
- Quality Considerations:
- Verification of purity (>99 % by HPLC).
- Absence of UV-induced isomers (e.g., 5-cis-D₂).
- Accurate potency labeling.
- Preferred Supplements: Good Manufacturing Practice (GMP)-certified supplements that use non-GMO, non-irradiated substrates are preferred for consistency and safety.
Where to Buy Vitamin D2 (Ergocalciferol)
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