Quercetin-Eudragit® polymer complexes with enhanced loading, solubility, stability, and site-specific targeting

Quercetin is a natural dietary compound known for its potential to prevent chronic diseases. However, the translation of this success to humans is hindered due to quercetin's poor oral bioavailability, attributed to its extremely low water solubility and permeability. These challenges affect the oral absorption of quercetin.

The current work describes a polymer-based platform specifically targeted for the delivery of quercetin to the colon. Quercetin complexes were prepared using co-precipitation. The polymers used are Eudragit® S100/L100/L100-55. Ethanol and polyvinyl alcohol are the solvent and surfactant respectively in the complex formation process.

The formed polymer complexes demonstrate a high loading capacity, reaching approximately 315 μg/mL of quercetin. The complexes obtained were amorphous in the solid state and soluble in buffer with pHs > 5.5. The resulting Quercetin-Eudragit® complexes demonstrate significantly increased aqueous solubility, reaching concentrations > 1 mg/mL. The polymer complexes were more stable for > 30 h in aqueous solutions compared to quercetin. The solubilized Quercetin-Eudragit® formulations demonstrated enhanced reduction in cell viability in colon cancer cells HCT116 and HT29 when compared to quercetin.

In summary, the study demonstrates the successful development of a polymer-quercetin complex with improved loading, solubility, stability, and targeted delivery properties.