Fabrication, characterization, and in vitro release of vitexin-loaded chitosan nanoparticles

Vitexin is a natural bioactive compound with many functional properties. However, its poor water solubility and dispersion stability and short half-life limit its practical applications for targeting specific sites. The current work demonstrates that encapsulation of vitexin in chitosan nanoparticles via an oil-in-water emulsion followed by ionic gelation using pentasodium triphosphate overcomes these limitations. The successful loading of vitexin into chitosan nanoparticles was confirmed using ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. The vitexin-loaded chitosan nanoparticles were spherical, 50–250 nm in diameter, and had a negatively charged surface (zeta potential of -6.2 mV to -13.8 mV), 2.8–21.0% loading capacity (LC), and 16.6–58.2% encapsulation efficiency. Vitexin LC increased with increasing initial concentration. The vitexin-loaded chitosan nanoparticles showed antioxidant and lipid oxidation retardation activities that increased as a function of LC. Encapsulation of vitexin into chitosan nanoparticles could improve its dispersion stability in water. Vitexin release from chitosan nanoparticles into the buffer media was faster at pH 11 (completed within 10 days) than at pH 7 (80 days) and 3 (> 4 months). These results suggest that vitexin-loaded chitosan nanoparticles are stable in acidic and neutral pH media, and the loaded vitexin can potentially withstand the harsh gastrointestinal environment.