Preparation,characterization And Preliminary Pharmacokinetic-pharmacodynamics Studies Of Gambogenic Acid Nanoemulsion

Objective:Gambogenic acid（GNA）is an effective active ingredient isolated from Garcinia cambogia,which has a broad anti-cancer spectrum and strong anti-cancer activity.It has no effect on the hematopoietic system and immune function of normal animals and can selectively act on tumor cells.However,its clinical application is limited due to its shortcomings such as high vascular irritation,short half-life,poor water solubility,etc.Therefore,to improve the water solubility,prolong the half-life,and enhance the anti-tumor activity of GNA in vivo and in vitro,a nanoemulsion was fomulated to encapsulate GNA.And the reduction of its vascular irritation is completed by oral administration.Methods:（1）This topic firstly investigated the solubility of GNA in different oil phases,surfactants and co-surfactants,and screened out the optimal composition for preparing GNA nanoemulsion.Secondly,through the drawing of pseudo-ternary phase diagram,the investigation of preparation factors and the selection of dosage,gambogenic acid nanoemulsion（GNE）suitable for oral administration was formed and calculated its solubility.GNE was characterized by appearance,type,particle size,polydispersity coefficient,TEM,stability and in vitro release.（2）Select 4T1 breast cancer cells and investigate the inhibitory effect of GNE on 4T1 cells by MTT experiment.（3）Evaluate the in vivo anti-tumor pharmacodynamics of GNA and GNE by using 4T1 transplanted tumor mouse model.（4）A single dose of 15 mg/kg in SD rats was used to compare the differences in the pharmacokinetic parameters of the GNA and GNE groups.Results:（1）The excellent blank nanoemulsion prescription was medium chain triglyceride,polyoxyethylene hydrogenated castor oil,polyethylene glycol 400,water（0.3:0.47:0.23:1.0,m/m/m/m）.The obtained GNE was a clear yellow liquid with an encapsulation efficiency of 93.50%.Through the identification test of Sudan red（red oily dye）and methylene blue（blue water-based dye）,it can be seen that the GNE was an oil-in-water type.GNE had a spherical shape with uniform size,an average particle size of（45.28±0.32）nm and a polydispersity index（PDI）of（0.137±0.001）.Zeta potential of GNE was（-10.5±0.52）.Dilution test showed that GNE had good dilution.Physical stability showed that the particle size,encapsulation efficiency and appearance of GNE remained stable at 4°C for 4 weeks,with good storage stability.In vitro release studies showed that GNE had the properties of slow and sustained drug release,and GNA encapsulated by nanoemulsion can be stability in gastrointestinal juice.The release rate of GNA solution was rapid in the gastrointestinal juice for 6 hours,with a total cumulative release of 43.57%,while GNE only released 11.12%,which reduced the leakage of the drug.It indicated that GNE can be delivered to the blood circulation through oral administration in the form of a relatively complete nanoformulation.（2）The results of in vitro cell experiments showed that the IC₅₀ value of GNE on 4T1 cells was 3.353μmol/L,which was 0.55 times that of free GNA（6.041μmol/L）,indicating that GNE had a stronger inhibitory effect on 4T1.（3）The in vivo anti-tumor results showed that,compared with GNA group,GNE can significantly inhibit tumor growth in 4T1transplanted mice in either high or low doses,and the difference is statistically significant.（4）The UPLC-UV system was used to establish a GNA plasma sample analysis method,and the differences in pharmacokinetic parameters of GNA and GNE group after a single administration were compared;the results showed that the half-life of GNA was extended by at least 2.43 times and AUC increased by 22.86 times after being encapsulated by nanoemulsion.Conclusion:This study successfully prepared the GNE for oral administration,which improved the water solubility,prolonged the half-life,reduced vascular irritation,and showed strong anti-tumor efficacy both in vivo and in vitro.And it is an effective and potential nano formulation.