Phytosterol Oleate Ester Replacing Cholesterol to Enhance Lutein Liposome Stability: A Mechanistic Study

Hydrophobic bioactive compounds such as lutein exhibit poor water solubility and are prone to degradation. Liposomal delivery systems can enhance the solubility and physicochemical stability of lutein (LUT). Liposomes are primarily composed of phospholipids and cholesterol. Since phytosterol ester can reduce cholesterol levels and improve the performance of liposomes, this study used phytosterol oleate ester (POE) as a cholesterol substitute in the preparation of liposomes for delivering LUT (LUT-P-Lip). The physicochemical properties, microstructure, storage stability, antioxidant characteristics, and intermolecular interactions of the liposomes at different LUT concentrations were investigated. The results demonstrated that LUT-P-Lip had a size range of 50-100 nm, with intact morphology and uniform distribution. In vitro studies showed that LUT-P-Lip significantly enhanced the storage stability and antioxidant activity of LUT. The analysis of intermolecular interactions revealed that the enhanced stability was mediated by an increased number of hydrogen bonds and modulation of membrane fluidity. In conclusion, replacing cholesterol with POE during liposome formation enhances both the stability and antioxidant activity of the resulting liposomes.