In order to enhance lipophilicity and oral bioavailability of paeoniflorin (PF), this study developed paeoniflorin-phospholipid complex (PF-PLC) by solvent-evaporation method. The optimum preparation technology of PF-PLC was screened by the combination of single factor and orthogonal experiment. The physicochemical properties of PF-PLC were evaluated via differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) and oil-water partition coefficient study (lgP). The result of FTIR spectra indicated that there was some strong hydrogen bond interaction and good compatibility between the phospholipid molecule and PF in the complex. DSC and XRD structure analysis showed that PF was in form of amorphous structure in PF-PLC, and lgP of PF-PLC was enhanced, suggesting that the lipophilicity of PF-PLC was higher than that of PF. In vitro release of PF-PLC showed slower release than PF solution with its cumulative release rate of 93.81% at 24 h compared to 93.43% of PF at 1.5 h. In pharmacokinetic experiments, the AUC and Cmax of the PF-PLC were 1.97-fold and 2.5-fold higher than PF solution. These results suggested that PF-PLC could enhance lipophilicity and oral bioavailability of PF and provide a promising delivery system for the application of PF.
Keywords: Paeoniflorin; lipophilicity; oral bioavailability; phospholipid complex.