Study Of NK4 And Stearyl Glycyrrhetinate Dual-ligand Functionalized Hydroxycamptothecin Liposomes

Objective:A novel drug delivery system based on liver-target NK4and stearyl glycyrrhetinate dual-ligand functionalized liposome was established.Hydroxycamptothecin,an effective anticancer component present in traditional Chinese medicine,was capsulated in the liposomes,and the ligand-mediated drug delivery system was designed to target liver tumor.Methods:The thin film dispersion method was employed to preparation the liposomes including HCPT-Lip,NK4-HCPT-Lip and NK4-SG-HCPT-Lip.The liposome formulation was optimized based on the ratios of phospholipid to drug and phospholipid to cholesterol,and the phospholipid concentration.The encapsulation rate of liposomes was investigated by the single factor analysis and the Box-Behnken response surface method.The properties of liposomes,including TEM micromorphology,particle size,Zeta potential,encapsulation efficiency（EE%）,drug loading capacity（DL%）,in vitro release and stability,were characterized.In vitro antitumor experiments,the cytotoxicity of drug-loaded liposomes toward Hep G2 cells was compared with the commercial HCPT injection by the MTT method.In pharmacokinetics and tissue distribution studies,SD rats and KM mice as experimental subjects were used to evaluate the pharmacokinetic characteristics and the liver-target ability of the drug delivery system respectively.Results:The optimal formulation of HCPT-Lip can be defined as the ratios of phospholipid to drug（10.93:1）and phospholipid to cholesterol（3.25:1）.The optimal liposomes with the encapsulation rate of 86.73±3.97)%,the drug loading of 2.69±0.14%,the average particle size of 168 nm（the PDI of 0.221）,and the zeta potential of-21.8 m V,were obtained.TEM photographs showed that the resulting liposomes were round or quasi-circular and uniform.In vitro release test showed the sustained-release behaviors of the three drug-loaded liposome preparations,compared to the commercial HCPT injection as reference.The stability study showed that there was no significant change in the appearance,particle size,and encapsulation efficiency of the liposome when stored at 4°C for 1 month.MTT study showed that the time-dose dependent inhibition of Hep G2 cells was observed in all three drug-loaded liposomes and commercial HCPT injection.The IC50 of HCPT-Lip,NK4-HCPT-Lip,NK4-SG-HCPT-Lip and commercial HCPT injection were 31.75,23.74,18.80 and 11.24μg/m L for 24 h,and the IC50 at 48 h were 7.93,3.91,1.17 and 10.06μg/m L,respectively.In vivo studies showed that the pharmacokinetics behavior of the target liposomes followed three-compartment model in rats,and commercial HCPT injection preferred one-compartment model.The high value of t_1/2indicated that the higher level of HCPT in the liposomes was kept in the systemic circulation of rats than that of HCPT injection,which would significantly prolong the drug retention time in blood.The tissue distribution study indicated that NK4-SG-HCPT-Lip possessed the highest target efficiency in mouse liver and the longest retention time.Conclusions:The prepared NK4-SG-HCPT-Lip exhibited uniform particle size and high encapsulation efficiency.Compared to simple HCPT nano-preparation and HCPT injection,the dual-ligand-modified liposomes can significantly improve the bioavailability of drugs,prolong the retention time in circulation,reduce drug distribution in kidney tissue,and target liver tissue for enhancing antitumor efficacy with relived nephrotoxicity.