Enhanced Oral Bioavailability of Oleanolic Acid in Rats with Phospholipid Complex

To improve the bioavailability of oleanolic acid (OA), OA-phospholipid complex (OA-PLC) was prepared and evaluated with solubility, differential scanning calorimetry, X-ray powder diffractometry, IR spectroscopy, dissolution study and pharmacokinetic characteristics in rats. Concentrations of OA after oral administration of OA-PLC and OA aqueous suspension in rats were determined by high-performance liquid chromatography/mass spectrometry /mass spectrometry. Solubility of OA-PLC in water and in n-octanol was effectively enhanced by 300 times and 1.2 times, respectively. Spectra of DSC, XRD and IR showed that OA-PLC was formed. Cmax of rats treated with OA and OA-PLC is 0.47 and 1.18 µg/mL, respectively. AUC0→24h and AUC0→∞ values in rats of group OA-PLC were increased significantly (p<0.01) by 2.06 and 2.16 times compared with those of group OA, respectively. This study indicates the superiority of OA-PLC over OA, in terms of enhanced water and lipid solubility and improved bioavailability in rats.