Polyglycerol fatty acid ester contributes to the improvement and maintenance of water solubility of amorphous curcumin by suppressing the intermolecular interaction and the diffusion rate of curcumin

Curcumin (CUR), a polyphenol, is an attractive component of functional foods, owing to various physiological activities. However, CUR is highly hydrophobic, insoluble in water, and difficult to absorb in the body. Here, we report an amorphous CUR formulation containing the dispersant polyglycerol fatty acid ester (PGFE), demonstrating high and stable water solubility. Improved water solubility enhanced the absorbability of CUR in our amorphous formulation along with enhanced triglyceride inhibition, compared to that in a commercial formulation. Nuclear Overhauser effect spectroscopy (NOESY) analysis revealed that PGFE reduced CUR-CUR interaction, resulting in higher dispersion and improved solubility of CUR. Taylor dispersion analysis showed a lower diffusion coefficient of CUR in the highly water-soluble formulation (with PGFE) than that in the low watersoluble formulation (without PGFE), which prevents recontact and recrystallization of CUR, which is trapped by PGFE. Overall, the amorphous CUR with high solubility could be used as a promising functional food.