The Primary Research On Berberine Conventional And Long-circulation Liposomes

In recent years,accumulating studies have found that berberine hydrochloride has anti-tumor effects,but the studies in vivo showed that it has poor oral absorption and therefore likelihood to achieve the desired anti-tumor concentration.Moreover,direct intravenous administration often produce a variety of adverse reactions.Therefore,how to improve the bioavailability while ensure a satisfactory safety profile has become the focus of extensive research.The liposomes have similar structures to bio-films and can increase the affinity for cells,achieve slow release,and increase bioavailability reduce the side effects.Therefore,liposomes have become the ideal transport carriers for anticancer drugs.Studies have reported that the long-circulating liposomes can improve the stability,reduce the damage of macrophage system(MPS)and plasma composition,prolong the drug circulation time in vivo,increase the leakage of drug in tumor neovascularization,and promote the drug accumulation in tumor tissue.Therefore,the current thesis is designed to prepare the common liposome,and long-circulating liposomes in the first place,and investigate the distribution profile and-tumor effect in vivo.Based on the above purpose,this thesis work mainly consists of the following aspects.Firstly,we established the method of analysis in vitro and EE for BH liposomes.With EE as index,ultimately,We determine the pH-gradients combined with thin-film dispersion method to prepare liposomes.We used concentration of phospholipids,lecithin cholesterol ratio,drug-lipid ratio,the external phase pH,incubation temperature and time to investigate the effect on the EE of liposomes.On this basis,with the concentration of phospholipids,lecithin-cholesterol ratio,drug-lipid ratio,the external phase pH as factures,the EE as evaluation index,we used the method of orthogonal design L9(34)to determine the best process and parameter to prepare BH liposomes.The result showed that the most satis-factory liposomes could be prepared with phospholipid-cholesterol ratio at 3:1,the drug-phospholipid ratio at 1:15,the phospholipid concentration at 30 mg/mL,and the the external phase pH at 7.0.We also prepared long-circulating liposomes by adding 5%mol PEG2000-DSPE to the conventional liposomes.The EE of conventional and long-circulating liposomes were more than 80%.as determined by Sephadex-column method.We investigated the physicochemical properties of the conventional and long-circulating liposomes,including particle size,morphology,Zeta potential,in vitro release,content determinati-on and stability.The results showed that the size distribution range were narrow and heterogenous.The average particle size were 123.3 nm and 116.9nm;the Zeta potential were-20.0mV and-28.7mV;TEM observation showed they all had the uniform particle size and good dispersion.The liposomes showed good stability after 2 months at 4℃.Dialysis study showed that both of the liposomes can prolong the drug release,and long-circulating liposomes were even better.Pharmacokinetic studies of the liposomes were performed in rats.The berberine hydrochloride solution and the two formulation liposomes were administered though intravenous injection.The results show that the t1/2 and AUC(0-∞,)of long-circulating liposomes were 34.1 and 6610.5 times higher to the solution group,respectively.The t1/2 and AUC(0-∞)of the conventional liposomes were 23.6 and 3995.9 times higher.The results indicated that the long-circulating liposomes can maintain a long blood circulation time.In addition,the CL of conventional liposomes was 1.5 times higher to the long-circulating liposomes,indicating that the elimination of the long-circulating liposomes was slower in vivo.The distribution in the tumor-bearing mice was also observed and the results showed that long-circulating liposomes can reduce the distribution of berberine in the heart while increasing its concentration in tumor tissues.To investigate the in vivo anti-tumor efficacy,we established tumor model by inoculating with gastric cancer SGC-7901 to BALB/c nude mice.The tumor volume and body weight were measured and the overall reactions of the mice were recorded every other day after administration for a 20-day duration.The results showed that the inhibition rate of solution group,conventional and long-circulation liposome were 33.61%,38.86%and45.76%,respectively,indicating that the long-circulating liposomes has a relatively potent inhibitory effect on tumor growth in vivo.The live state of the mice in each group showed that the body temperature immediately decrease after berberine hydrochloride was administered,activity sluggish,and gradually returned to normal,the eye inflammation occurs during the period of administration.While the mice eating,behavior and activity state of liposomes groups were normal,indicating that berberine hydrochloride liposome formulations can improve adverse reactions of berberine hydrochloride intravenously,has the in-depth research value.