Novel Ascorbic Acid Co-Crystal Formulations for Improved Stability

A series of co-crystals of ascorbic acid were prepared with equimolar amounts of co-crystal formers (CCFs), including isonicotinic acid, nicotinic acid, 3,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid and m-hydroxybenzoic acid, by slow solvent evaporation and solvent-assisted grinding. The co-crystals were characterized by single-crystal X-ray diffraction spectroscopy, powder X-ray diffraction, IR spectroscopy, differential scanning calorimetry and thermogravimetric analysis. Molecular dynamics (MD) simulations further validated the interaction energy and the possible intermolecular hydrogen bonds among VC and CCFs. The co-crystals showed improved stability when exposed to different wavelengths of light, pH and temperatures compared to the free analogue, especially at higher pH (similar to 9) and lower temperature (similar to 4 degrees C).

Automated summary

A series of co-crystals of ascorbic acid were prepared using different co-crystal formers and characterized using various techniques. The co-crystals exhibited improved stability under different conditions and molecular dynamics simulations confirmed the interactions and hydrogen bonding involved in the co-crystal formation.