[Cholesteryl hemisuccinate as liposomal membrane stabilizer and its use in the preparation of saikosaponin-D liposomes].

AIM: To study the membrane stabilization effect and mechanism of cholesteryl hemisuccinate (CHEMS) on dipalmitoylphosphatidylcholine (DPPC) liposomes; Saikosaponin-D (SSD) liposomes were prepared by using CHEMS as a membrane stabilizer and its encapsulation efficiency and hemolytic activity were evaluated. METHODS: Differential scanning calorimetry (DSC) and calcein release were used to study membrane stabilization effect of CHEMS on DPPC membrane, Fourier transform infrared spectroscopy (FT-IR) was used to study the interacting mechanism of CHEMS with DPPC, sedimentation experiment was done to study the interaction of CHEMS with SSD and hemolytic study was used to evaluate the hemolytic activity of SSD-liposomes with CHEMS as membrane stabilizer. RESULTS: DSC analysis showed that CHEMS and cholesterol (CHOL) could all decrease the Tm value slightly and the deltaH value markedly. CHEMS was more effective than CHOL in decreasing the deltaH value of DPPC membrane. It suggested that CHEMS was more effective in increasing DPPC membrane stability. It was also proved by calcein release study carried out both in PBS and 30% plasma. The findings by FT-IR suggested that CHEMS has both hydrogen bond and electrostatic interaction with the polar head of DPPC. CHEMS did not form insoluble complex (INCOM) with SSD by sedimentation experiment. Stable SSD-liposomes were prepared using DPPC and CHEMS and decreased effectively the hemolytic activity of SSD, SSD-liposomes may be given intravenously at a concentration of 15 microg x mL(-1), while free SSD was forbidden to be given intravenously. CONCLUSION: CHEMS was more effective than CHOL in increasing DPPC membrane stability, and it could be of great use in the preparation of cholesterol-dependent hemolytic saponins-liposomes. The hemolytic activity of SSD-liposomes was greatly reduced, allowing a possible concentration of 15 microg x mL(-1) to be intravenously administered.