Meglumine-enhanced water solubility and stability of quercetin at moderate pH via liposome encapsulation
Ferdinand Holzhausen, Adrien Fusina, Michael Loessl, Didier Touraud, Antje J. Baeumner, Véronique Nardello‐Rataj, Werner Kunz
Abstract
• Even a highly oxygen-sensitive polyphenol such as quercetin can be successfully encapsulated in liposomes by adding meglumine to the aqueous solution. In the present work, the flavonoid quercetin was encapsulated into liposomes from an aqueous solution using meglumine as solubility enhancer and stabilizer for quercetin. This study was a proof of principle to demonstrate the feasibility of the pH-driven (or pH jump) method even with very oxidation-sensitive polyphenols. We thus investigated meglumine addition together with the standard thin-film hydration method to prepare liposomes. Furthermore, the pH was initially set at 9 to enhance the water-solubility of quercetin and was lowered to 7 after encapsulation. The liposomes were prepared using DPPC, DPPG, cholesterol and DMPE lipids and two different saline buffer solutions containing either sucrose or meglumine. Successful encapsulation of quercetin was confirmed by Differential Pulse Voltammetry. The estimation of the degree of oxidation of quercetin inside the liposomes was performed by High-Performance Liquid Chromatography. It was found that a significant amount of unoxidized quercetin was encapsulated in the liposomes from an aqueous solution, notably in the liposomes prepared with meglumine buffer solution.