Preparation And Properties Of Shikonin Liposome Gel

Shikonin is one of important active constituents extracted from the roots of Lithospermum,which has been used in clinical widely as traditional Chinese medicine,such as the treatment of skin eczema,pruritus,sores and ulcers.However,Shikonin is a fat-soluble compound,which was reported to limit its drug efficacy and lead to its low bioavailability.Besides,Lithospermum was also reported to contain pyrrolizidine alkaloids(Pas),which is existed widely in natural plants and proved to be a liver toxity.These two disadvantages limit the application of Lithospermum.In order to improve the bioavailability and safety of Lithospermum,this work mainly focuses on the development of a novel liposomegel containing Shikonin and contains three parts of study:Firstly,Shikonin was extracted by refluxing with organic solvent,and the analytical method by high performance liquid chromatography(HPLC)was established for the determination of Shikonin in vitro.The Shikonin was also characterized by thin layer chromatographic analysis(TLC).The partition coefficient of shikonin in n-octanol/water was examined and the results showed that the LgP of Shikonin was 2.7234.Shikonin liposomes and alkalized Shikonin liposomes were prepared by ethanol injection.The morphology of the liposomes was observed by transmission electron microscopy(TEM)and the particle size and Zeta potential of the liposomes were determined by the nanoparticle size potential analyzer.The entrapment efficiency of the liposomes was determined by high-speed centrifugation.The in vitro release characteristics were determined by dynamic dialysis.The results showed that the average particle size of shikonin liposomes and alkalized shikonin liposomes were 124.7 nm and 104.2 nm,respectively.The Zeta potentials were-14.6 mV and-14.8 mV,respectively,and the entrapment efficiencies were 20.37%and 43.67%.The cumulative releases measured by dynamic dialysis method were 47.95%and 65.82%,respectively.Shikonin liposomegel and alkalized Shikonin liposomegel were preparedbased on above work.Carbomer-940 as a gel matrix,methyl paraben as a preservative,glycerin as a humectant,Tween-80 as a surfactant,triethanolamine as a pH regulator,borneol and mint ice play promote the role of penetration.The stability and in vitro release characteristics of the gel were investigated.The results showed that both Shikonin liposomegel and alkalized Shikonin liposomegel had no obvious change under centrifugation and freezing,but it was easily affected by temperature,so these two gels should be stored at low temperature.The cumulative releases of them were 44.83%and 28.41%,respectively.