Chondroitin

Chondroitin is a sulfated glycosaminoglycan (GAG) that forms a major component of the extracellular matrix in cartilage, tendons, and connective tissue. It is most widely used as a dietary supplement to support joint health by supporting the structural integrity and lubrication of articular cartilage.

• Chemical structure: Chondroitin is a linear polymer of repeating disaccharide units: β‑D‑glucuronic acid (or L‑iduronic acid) linked β‑1→3 to N‑acetyl‑D‑galactosamine that is variably sulfated at the 4‑ or 6‑position.
• Chemical formula: The generic chemical formula for the repeating disaccharide unit is C₁₄H₂₁NO₁₆S (for the 4‑sulfated form).
• Polymer size: The full polymer can contain 10–30 kDa of repeating units (average molecular weight ≈ 20–50 kDa).
• IUPAC nomenclature: IUPAC nomenclature for the monomer is (4‑Sulfated) N‑acetyl‑β‑D‑glucosaminyl‑β‑1,4‑D‑glucuronic acid.
• Properties: The high density of sulfate groups imparts a strong negative charge, enabling water retention and interaction with positively charged proteins (e.g., growth factors). It is a non‑ionic, water‑soluble, hygroscopic powder with a pH‑neutral, slightly acidic pH in aqueous solution (pH 4–5).

• Primary sources: Commercial chondroitin is primarily extracted from cartilage of bovine, porcine, or shark (cartilaginous fish) sources.
• Shark cartilage: The most common industrial source is shark cartilage, harvested from species such as Chondrichthyes (e.g., shark fin) because of its high sulfation (especially 4‑sulfated chondroitin sulfate A).
• Alternative sources: Bovine and porcine cartilage provide a mixture of chondroitin‑A and chondroitin‑C (6‑sulfated) and are preferred when religious or dietary restrictions preclude shark.
• Extraction process: Extraction involves enzymatic digestion (e.g., papain), purification through ultrafiltration, and sterilization by gamma‑irradiation.
• Synthetic chondroitin: Some manufacturers produce synthetic chondroitin via bacterial fermentation (e.g., E. coli engineered to produce chondroitin sulfate) which offers a more controlled sulfation pattern and avoids marine‑source contaminants.
• Quality control: Quality criteria include ≥ 90 % chondroitin sulfate purity, low heavy‑metal content (< 10 ppm), and absence of endotoxin.
• Third-party testing: Third‑party testing (USP, NSF) is recommended to verify purity and absence of animal‑specific pathogens.