Production of stabilized quercetin aqueous suspensions by supercritical fluid extraction of emulsions

• Encapsulated quercetin was produced in sub-micrometric scale.
• The quercetin encapsulation efficiency was near 70%.
• Residual organic content in samples is under 300 ppm.
• Antioxidant activity of encapsulated quercetin increased comparing to pure quercetin.

Quercetin is a flavonoid with highly promising bioactivity against a variety of diseases, due to its strong antioxidant, antiviral and antihistaminic effect, but these applications are limited by the low solubility of quercetin in gastrointestinal fluids and the correspondingly low bioavailability. The objective of this work is to produce encapsulated quercetin particles in sub-micrometric scale, in order to increase their low bioavailability. These particles were produced by extraction of organic solvent from oil in water emulsions by supercritical fluid extraction of emulsions (SFEE). Due to the rapid extraction of organic solvent by this method, the disperse organic phase becomes rapidly supersaturated, causing the precipitation of quercetin particles in sub-micrometric scale, encapsulated by the surfactant material. Two different biopolymers (Pluronic L64® poloxamers and soy bean lecithin) were used as carriers and surfactant materials. In experiments with Pluronic, needle quercetin particles were obtained after SFEE treatment, with particle sizes around 1 μm and poor encapsulation efficiency. In case of soy lecithin, quercetin-loaded multivesicular liposomes were obtained, with a mean particle size around 100 nm and around 70% encapsulation efficiency of quercetin, without presence of segregated quercetin crystals.

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