Preparation of Daidzein-Phospholipid Complex and Its Bioavailability Study in Rats

OBJECTIVE To optimize preparation methods of daidzein-phospholipid complex and determine its bioavailability in rats after oral administration. METHODS Using binding ratio of daidzein to phospholipid as evaluation parameter, the preparation methods for daidzein-phospholipid complex were optimized by means of single factor tests and orthogonal design. Apparent solubility of daidzein, physical mixture and daidzein-phospholipid complex in water and n-octanol was determined, respectively. The concentrations of daidzein in plasma samples in rats were analysed by LC-MS/MS after oral administration of daidzein suspension, physical mixture and daidzein-phospholipid complex, and their bioavailabilities were compared. RESULTS The daidzein-phospholipid complex was prepared by stirring and refluxing phospholipid Epikuron 200 and daidzein (molar ratio 1.5∶1) in ethanol at a temperature of 60 ℃ for 2 h. Apparent solubility of daidzein-phospholipid complex were 3.1 and 5.4 folds compared with daidzein in water and n-octanol, respectively. Pharmacokinetic parameters of Cmax were (667±65) ng·mL^-1 and (7 509±688)ng·mL^-1, Tmax were (3.00±0.82)h and (0.42±0.17)h，AUC0–∞ were (8 302±590)ng·h·mL-1 and (28 870±2 411)ng·h·mL^-1 after oral administration of daidzein suspension and daidzein-phospholipid complex in rats, respectively. The relative bioavailability of daidzein-phospholipid complex to daidzein was 3.48. CONCLUSION Apparent solubility of daidzein- phospholipid complex both in water and n-octanol were improved, thus, increasing gastrointestinal absorption. As a result, the bioavailability was increased after oral administration of daidzein-phospholipid complex in rats.