Hyaluronic Acid (Sodium Hyaluronate)

Hyaluronic acid is a linear glycosaminoglycan built from alternating D-glucuronic acid and N-acetyl-D-glucosamine units, and it is traded almost entirely as its sodium salt, sodium hyaluronate (CAS 9067-32-7; free acid CAS 9004-61-9). The repeating disaccharide is C14H20NNaO11 at 401.3 Da, and chain length rather than composition is what separates commercial grades: material is sold anywhere from oligosaccharide fractions below 10 kDa up to high-molecular-weight polymer above 1,800 kDa. Thovek's material is produced by fermentation of a non-GMO Streptococcus equi subsp. zooepidemicus culture, with the bacterial cells inactivated and removed, and the polymer recovered by filtration, ultrafiltration, solvent precipitation and drying. This is now the dominant route. The older rooster-comb extraction is avian in origin and carries a sulphated-glycosaminoglycan limit under the European Pharmacopoeia that fermentation material does not need, which is one reason origin should always be stated on the specification rather than assumed. Food and cosmetic grade is specified on sodium hyaluronate content not less than 91.0% with D-glucuronic acid not less than 44.0% by the carbazole method, protein not more than 0.1%, loss on drying not more than 10.0%, pH 6.0 to 8.0 at 5 mg/mL, heavy metals not more than 20 ppm and arsenic not more than 2 ppm. Pharmacopoeial grade follows the Ph. Eur. sodium hyaluronate monograph, which assays 95.0 to 105.0% on the dried substance, requires intrinsic viscosity within 90 to 120% of the labelled value, caps protein at 0.3% (0.1% where the material is intended for parenteral manufacture) and limits nucleic acids to an absorbance of 0.5 at 260 nm. Because hydration rate, viscosity build and mouthfeel all track molecular weight, the grade should be picked against the format: low and ultra-low fractions dissolve quickly and stay thin in shots, gummies and effervescents, while high-molecular-weight material builds body and is normally reserved for topical and non-oral work. Fermentation-derived sodium hyaluronate is non-animal and suits vegan and vegetarian positioning, and it is free of milk, egg, fish, crustacean, gluten and tree-nut material. Buyers with a soy declaration to make should still request the fermentation medium composition, because peptones of soy or dairy origin are used by some producers even though they are removed downstream. In the EU, a consultation under Article 4 of Regulation (EU) 2015/2283 concluded that sodium hyaluronate produced by this fermentation route is not a novel food when used in food supplements, which removes a common barrier to oral launches; the position for other food categories and for other markets must be checked separately. The powder is very hygroscopic, so it is packed in sealed foil with desiccant and should be resealed immediately after sampling. Each lot ships with a certificate of analysis stating molecular weight or intrinsic viscosity, glucuronic acid, protein, loss on drying, heavy metals and microbiology, plus SDS, allergen, BSE/TSE, non-GMO and halal and kosher documentation where held.