Solubility and Permeability Improvement of Quercetin by an Interaction Between α-Glucosyl Stevia Nanoaggregates and Hydrophilic Polymer.

The effect of composite formation between α-glucosyl stevia (Stevia-G) and hydrophilic polymers on solubility and permeability enhancement of quercetin hydrate (QUE) was evaluated. Polyvinylpyrrolidone K-30 (PVP), hydroxypropyl methylcellulose 2910-E (HPMC), and hydroxypropyl cellulose SSL (HPC) were selected as candidate hydrophilic polymers. Fluorescence studies with pyrene and curcumin suggested composite formation occurs between Stevia-G aggregate and polymers. Furthermore, the strength of interaction between Stevia-G aggregate and polymers was as follows: PVP > HPMC > HPC. Evaporated particles (EVPs) of QUE with Stevia-G and polymers showed synergic QUE solubility enhancement. Solubility of QUE from the EVPs was enhanced in the following order: Stevia-G/PVP > Stevia-G/HPMC > Stevia-G/HPC, in accordance with the degree of interaction. Enhanced membrane permeability of QUE from the EVPs of Stevia-G/PVP was confirmed using Caco-2 cells. The amount of QUE that permeated Caco-2 cells from the EVPs of Stevia-G/PVP was 13.7-, 4.7-, and 2.1-fold higher than that of the untreated QUE powder, EVPs of Stevia-G, and EVPs of PVP, respectively. These results indicated that the composite formed by Stevia-G and PVP can dramatically enhance the solubility and membrane permeability of QUE.