Phytoglycogen improves the water solubility and Caco-2 monolayer permeation of quercetin

The study examined the capability of phytoglycogen (PG) to improve the water solubility of quercetin (QC). PG-QC formulations were prepared by mixing a QC ethanol solution with a PG aqueous solution followed with vacuum drying of the supernatant. PG-QC formulations with various PG to QC ratios were prepared; the solubility of QC reached 241.76μg/mL at PG/QC ratio of 30/1 compared with approximately 4.32μg/mL of QC alone. The X-ray powder diffraction and FTIR analyses showed a significant reduction of QC crystallinity upon formulating with PG that was associated with the intermolecular hydrogen bonding between the hydroxyl groups of QC and PG. The Caco-2 cell monolayer permeation tests showed that PG-QC formulations resulted in substantially enhanced cellular uptake and transepithelial permeation of QC, which was related to the much-enhanced QC solubility. This study showed the potential of using PG to formulate poorly water-soluble ingredients such as QC.