ABSTRACT
Objective To optimize the preparation technology for Centella asiatica total glucosides (CTG) liposome and to investigate its percutaneous permeability in vitro. Methods Liposomes were prepared by reverse-phase evaporation technique. Taking the entrapment efficiency of madecassoside and asiaticoside as indexes, the preparation of liposome was optimized by using single factor and Box-Behnken response surface method. The properties of liposomes including morphology, entrapment efficiency, mean diameter, Zeta potential, and accumulative release were studied. Results The optimal formulation was lecithin-cholesterol (4:1), lecithin-CTG (23.22:1), and organic- aqueous (7:1). The liposome was smooth and spherieal in appearance, mean diameter, and Zeta potential were 201.7 nm and -15.7 mV, respectively. The entrapment efficiency of madecassoside and asiaticoside were 75.85% and 84.94%. The in vitro 12 h accumulative release was 52.10% and 45.97%. The equations for the permeation rate of madecassoside and asiaticoside in liposomes were Q = 67.93 t1/2-50.34, R2 = 0.988, Q = 139.74 t1/2-241.2, R2 = 0.987, respectively. The retention amount in the skin was 76 μg/cm2 and 48.7 μg/cm2, which were 1.56 and 1.18 times higher than those of solution. Conclusion The optimized process is rational, feasible, and good stability. The CTG liposome prepared in this study have the smaller size, the higher encapsulation efficiency, higher retain in skin and obvious sustained-release effects.
ABSTRACT
Objective: To study the intestinal absorption characteristics of the liposome encapsulated Centella asiatica total glucosides in vitro. Methods: Dialysis method was adopted to study the stability of the liposome encapsulated C. asiatica total glucosides in both PBS and Tyrode solution. RP-HPLC was adopted to detect the chromatographic profile of the sample solutions. To research the in vitro intestinal absorption properties of C. asiatica total glucosides and its liposome in isolated everted intestine model, the cumulative absorptive percentages of them in the different intestines are calculated and the cumulative absorption curve of them are drawn, in which the cumulative absorptive percentages of them are calculated by the amount of asiaticoside, and the intestinal absorption effects of them are compared. Results: The results show that the lipsome encapsulated C. asiatica total glucosides could exist stably in the PBS and Tyrode solution. C. asiatica total glucosides and its liposome could be absorbed in the small intestine and have no significant absorption site. The uptake of asiaticoside in ileum increased with time prolonging, and there was no absorptive saturation within 120 min. During the ileum absorption, the liposome encapsulated C. asiatica total glucosides have a higher percentage and a higher quantity of cumulative absorption than the drug of C. asiatica total glucosides, which showed that apparent permeation coefficient was higher significantly. Conclusion: The encapsulated C. asiatica total glucosides could promote the absorbtion of C. asiatica total glucosides in the ileum of rats, which provides the experimental evidence for the development of the oral dosage forms of C. asiatica total glucosides.