Study On Preparation And Properties Of Liposome Encapsulating Cyclodextrin And Glutathione Inclusion Complexes

Glutathione exists in two forms:reduced(GSH)and oxidized(GSSG).GSH can directly or indirectly participate in many important physiological metabolisms,and is one of the important antioxidants in living organisms.Glutathione is widely used in medicine and food industry.However,the GSH solution is unstable,prone to oxidation and degradation,and has low bioavailability.Liposome are lipid vesicles composed of phospholipid bilayers surrounding an aqueous core that can be used as carriers to encapsulate glutathione.However,available information on the encapsulation of glutathione in liposome are rare.Moreover,the encapsulation efficiency and drug loading of liposome are not ideal.Cyclodextrin(Cy D)is a cyclic oligosaccharide composed of D(+)-glucopyranose.In the production of pharmaceutical preparations,Cy D can be used as a host molecule to encapsulate drugs,which is helpful to improve the encapsulation efficiency and drug loading of liposome.In this paper,methods for the isolation and detection of glutathione liposome were determined,such as isolation of liposome on Sephadex G-25,high performance liquid chromatography(HPLC)method for quantitative detection of GSH and GSSG.Glutathione liposome were prepared after inclusion of several kinds of Cy D with GSH,which proved that the inclusion complexes ofα-Cy D and GSH can obviously improve the encapsulation efficiency and drug loading of liposome.Furthermore,the inclusion complexes ofα-Cy D and GSH were identified by molecular docking simulation,fourier infrared spectroscopy(FTIR)and nuclear magnetic resonance spectroscopy(~1H-NMR).The major and minor factors affecting the two-step emulsification method to prepare glutathione liposome were identified by the single-factor experiment and orthogonal experiment:The mass of hydrogenated soybean phospholipid(HSPC)>the volume of the internal water phase>the volume of the oil phase>the volume of the external water phase.Using the optimal formula combination,the encapsulation efficiency of the prepared glutathione liposome reached 88.0%,and the drug loading capacity was 220.0 mg.Then the quality of glutathione liposome was evaluated.The micromorphology of the glutathione liposome was circular,and the particle size was about 800 nm.Residual organic content in glutathione liposome has reached the standard for human medicine.The phase transition temperature of glutathione liposome is 51.3℃,and the zeta potential is-43.9 m V,which means that the liposome system is stable.Sucrose(100 mg/m L)was also selected as a good freeze-drying stabilizer for glutathione liposome.The glutathione retention rate was over 95%after lyophilization,and the particle size of the liposome did not change,and no aggregation occurred after rehydration.The glutathione liposome concentrate and its 5-fold and 10-fold dilutions were stored at4℃and 25℃for 90 days.Then,the contents of GSH and GSSG in internal and external solutions of liposome were detected by HPLC.Through the analysis and comparison,it was proved that the presence of liposome could significantly reduce the oxidation of the internal GSH and inhibit the degradation of glutathione.In addition,the leakage rate of glutathione in liposome will increase with time,temperature and concentration.Storage at 4℃and highly concentrated liposome solution are important conditions for ensuring low oxidation,low degradation and low leakage of glutathione.Finally,the in vitro release characteristics of glutathione liposome were studied using dynamic dialysis.The release rate of glutathione reached 67.03%,the release rate of glutathione(-Cy D)liposome was 19.07%,and the release rate of glutathione(+Cy D)liposome was 13.79%.Encapsulation of glutathione by liposome reduced the release rate of glutathione.Preparation of liposome by inclusion complexes of Cy D and GSH further reduced the release rate of glutathione.As we mentioned above,High-quality glutathione liposome were prepared with inclusion complexes ofα-Cy D and GSH.Liposome have an inhibitory effect on the oxidation of GSH and the degradation of glutathione encapsulated inside it.Liposome or cyclodextrin inclusion complexes liposome system has the effect of slow-release glutathione.This study provides new ideas for the protection of glutathione stability and lays a foundation for the industrialization of glutathione liposome.