Preparation, physicochemical evaluation and in vitro toxicity studies of HSPC and HSPC:DMPC stigmasterol-loaded liposomes

Phytosterols, like stigmasterol, have been studied for their antioxidant, immunomodulatory, and anticancer properties. However, their lipophilic nature and biological instability make it challenging to incorporate them in food supplements and medicinal products. Liposomes offer many benefits in sterols' entrapment and delivery them due to their high bioavailability, low toxicity, and ability to target specific tissues. The purpose of this study was to develop stigmasterol-loaded liposomes using HSPC (Hydrogenated Soy Phosphatidylcholine) and HSPC:DMPC (Dimyristoylphosphatidylcholine). The impact of increasing stigmasterol concentrations on the physicochemical stability of the liposomal formulations was analyzed by dynamic light scattering. The results showed that HSPC-based liposomes could incorporate higher amounts of stigmasterol compared to the HSPC:DMPC-based liposomes. Further analysis through differential scanning calorimetry revealed the formation of metastable phases in HSPC:DMPC:stigmasterol lipid bilayers. Finally, an in vitro MTS assay on HEK-293 cells demonstrated the low toxicity of the stigmasterol-loaded nanoplatforms. In conclusion, stigmasterol, not only contributed to the stability of liposomal formulation but exhibited low cell toxicity on HEK-293 line and could be used as a valuable compound in liposomal drug delivery formulation.