The cytotoxicity and apoptotic effect of phytoceramide IV （N-palmitoyl-phytospingosine） were investigated by preparaing the ceramide containing liposomes using cholesteryl hemisuccinate （CHEMS） and methoxypolyethylene glycol （2000） cholesteryl succinate （PEGCHS）. The ceramide-containing liposomes prepared using ultrasonication contained CHEMS and the phytoceramide IV at a molar ratio of 1：1. Gel chromatography and high performance liquid chromatography equipped with an evaporative light-scattering detection （HPLC-ELSD） were used to analyze the liposomes. The results show that the ceramide entrapment efficiency is over 90% and the molar ratio of phytoceramide IV to CHEMS is 1：1.4. The ratio of ceramide to CHEMS as well as the ultrasonication duration affects the liposome properties. The phytoceramide Ⅳ encapsulated in the liposomes reduces the cellular activity of the murine mastocytoma cell line P815 in a dose-dependent manner and the reduction of cellular activity is due to cell apoptosis. 4. 6-diamidino- 2-phenylindole dihydrochloride （DAPI） staining further supports this result. The encapsulation of highly hydrophobic ceramides into liposomal formulations could become a potential candidate for enhanced apoptosis.
