The interaction of paeonol with DPPC liposomes

Abstract

Differential scanning calorimetry and synchrotron X-ray diffraction techniques have been employed to investigate the interaction of paeonol with DPPC liposomes and to investigate the location of paeonol molecules in liposomes. The results showed that the location of the paeonol molecules in liposomes is concentration dependent. When the concentration of the paeonol is not more than 5 mol%, both main transition temperature and transition enthalpy of liposomes decrease with increasing the concentration of paeonol, indicating that paeonol molecules incorporate into the hydrophobic region of DPPC molecules. When the concentration of the paeonol is between 5 and 15 mol%, additional paeonol molecules will incorporate into the hydrophilic region of the DPPC molecules and interact with its polar groups, resulting in an increase tendency of the main transition enthalpy. When the concentration of the paeonol is more than 15 mol%, both main transition temperature and transition enthalpy of liposomes decrease with increasing the concentration of paeonol, indicating that the additional paeonol molecules locate at the region of hydrocarbon chains of DPPC again. Calorimetric data show that the main transition temperature of all paeonol/DPPC liposomes is lower than that of pure DPPC liposomes but the enthalpy of liposomes containing more than 10 mol% paeonol is higher than that of pure DPPC liposome, which is related to the nonsynchronous change of the head and tail part of DPPC molecules during the main transition. This study will play an important role in the further investigation of interaction of drugs with biomimetic membranes and in the further study of phase transition mechanisms of DPPC liposome.