Preparation of a nanoscale baohuoside I-phospholipid complex and determination of its absorption: in vivo and in vitro evaluations

BACKGROUND Baohuoside I is a potential anticancer drug for a variety of malignancies and has been approved for in vitro use. However, baohuoside I has very poor oral absorption. METHODS In the present study, we prepared baohuoside I-phospholipid complexes of different diameters and determined their physicochemical properties using transmission electron microscopy, ultraviolet spectroscopy, and differential scanning calorimetry. The in vitro absorption of baohuoside I and baohuoside I-phospholipid complexes of different sizes were compared using the Caco-2 cell culture model, and subsequently, the bioavailability of baohuosidel and its complexes were estimated in vivo. RESULTS Compared with the large-sized phospholipid complexes, a nanoscale phospholipid complex improved the oral bioavailability of baohuoside I. In addition, our results suggest that the smaller the particle size, the faster the complexes crossed the Caco-2 monolayer and the faster they were resorbed after oral administration in rats. The relative oral bioavailability of a nanoscale size 81 ± 10 nm baohuoside I-phospholipid complex (area under the concentration-time curve [AUC](0-∞)) was 342%, while that of baohuoside I and a 227.3 ± 65.2 μm baohuoside I-phospholipid complex was 165%. CONCLUSION We enhanced the oral bioavailability of baohuoside I by reducing the particle size of the phospholipid complex to the nanometer range, thereby improving its potential for clinical application.