ABSTRACT
OBJECTIVE: To investigate the intestinal absorption behaviors of Diospyros kaki L.f. extract (PLE) in self-microemulsifying drug delivery system (SMEDDS). METHODS: The concentration of quercetin, kaempferol and phenol red in rat intestinal perfusion solution was determined by HPLC. Rat single-pass intestinal perfusion technique was employed to assay the effects of concentrations of PLE in perfusion solution, intestinal segments and different formulations on the drug percentage absorbed (P) and the absorption rate constant (Ka). RESULTS: No significant changes of Ka and P were observed in different PLE concentrations. The main absorption segments of SMEDDS in rat intestines were the duodenum and ileum. The values of Ka and P of SMEDDS were significantly higher than the PLE solution (P<0.05). CONCLUSION: The absorption mechanism of PLE conforms to passive diffusion. The PLE SMEDDS presented the high absorption rate than conventional solution in rat intestine, which illustrates the potential use of SMEDDS for the delivery o f PLE by the oral route.
ABSTRACT
OBJECTIVE: To develop phospholipid vehicle to improve the bioavailability of curcumin after oral administration. METHODS: Two phospholipid vehicles, including phospholipid complex and liposome, were prepared. The characteristics, such as entrapment efficiency, shape, size, and structure, were compared. An in situ recirculation method was used to investigate the intestinal absorption of both phospholipid vehicles. RESULTS: Spherical or elliptical vesicles were observed under transmission electron microscope and atomic force microscope after the phospholipid vehicles were dispersed in water. The average entrapment efficiencies of phospholipid complex and liposome were (90.81 ± 1.32)% and (81.59 ± 2.41)% respectively. The mean sizes and zeta electric potentials were (91.69 ± 12.26) nm and (-13.73 ± 4.37) for the phospholipid complex, and (76.39 ± 8.58) nm and (-11.27 ± 1.26) for the liposomes. DSC, IR and Raman spectrum verified that there was reaction between curcumin and the phospholipid polar group around phosphorus atom in the complex but not in the liposomes. The apparent permeability coefficients (Papp) in the whole intestine were (1.1312 ± 0.0498) and (0.4780 ± 0.0120) 10 -6 cm-2 · s-1 for the complex and liposome respectively, which were 17.60 times and 5. 90 times higher than the crude drug. The absorption rate constants (Ka) and Papp of the complex were higher than the liposomes at duodenum, colon and ileum significantly. There was no difference at jejunum. CONCLUSION: Phospholipid complex can promote the absorption of curcumin in a larger degree than liposomes.