Surface modification by chitosan for improving stability and antioxidative activity of astaxanthin-loaded liposomes

Astaxanthin (AST) is a compound renowned for its extraordinary antioxidant and anti-inflammatory properties. However, its application is limited due to low solubility, instability and bioavailability. To overcome these drawbacks, we encapsulated AST in liposomes (AST-loaded liposomes, AST-LIP) using chitosan (CS) as coating materials by thin film dispersion and high-pressure homogenization. We examined the physicochemical characteristics (particle size, polydispersity index, zeta potential, encapsulation efficiency, fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analyzer (TGA)) of AST-LIP coated with various concentrations of CS, and confirmed the optimal concentration for the formulation of CS-coated AST-LIP was 1.5 mg/mL. Additionally, the storage stability and thermal stability analysis revealed that CS-AST-LIP exhibited significantly higher AST retention rates than AST-LIP under varying environmental conditions. Furthermore, CS-AST-LIP showed significantly higher DPPH·, OH· radical scavenging effects, and iron-reducing power than AST-LIP after storage for 4 weeks at 4 °C. For the cellular antioxidant assays, the CS-AST-LIP at the CS concentration of 1.5 mg/mL exhibited a satisfactory protective effect against oxidative damage induced by H2O2 in Raw264.7 cells. In conclusion, these findings highlight the potential of chitosan as a promising coating material for improving the storage stability, thermal stability and antioxidant activity of AST-LIP.