目的 制备维生素A(vitamin A,VA)修饰柴胡皂苷(saikosaponin,SS)a和SSd靶向脂质体并考察其体内外释药行为.方法 以包封率为指标,在明确大豆磷脂CS-95、胆固醇琥珀酰单酯{4-[(3β)-Cholest-5-en-3-yloxy]-4-oxobutanoic acid,CHEM}及靶向配体二硬脂酰基磷脂酰乙醇胺-聚乙二醇 5000-维生素A(DSPE-PEG-VA)最佳比例的基础上,通过薄膜分散超声法包载SSa/SSd后,结合后插法将DSPE-PEG-VA搭载在脂质体上,构建VA修饰SSa/SSd脂质体递药体系(VA-SSa/SSd-Lips).采用透射电子显微镜(transmission electron microscope,TEM)、动态光散射法测定脂质体形态、粒径及电位;鱼精蛋白沉淀法考察脂质体包封率及载药量;2%兔红细胞混悬液考察VA-SSa/SSd-Lips溶血性;正常大鼠尾静脉注射(1 mg/kg)VA-SSa/SSd-Lips溶液、SSa/SSd-Lips溶液和SSa/SSd溶液后,在不同时间点眼眶取血,测定各时间点大鼠血浆中SSa和SSd的药物浓度,利用DAS 3.0 软件计算药动学参数;小动物活体成像仪观测裸鼠尾静脉注射VA-DiR-Lips后体内荧光分布.结果 VA-SSa/SSd-Lips平均粒径为(142.43±0.60)nm,聚合物分散性指数(polymer dispersity index,PDI)为(0.31±0.052),Zeta电位为(-14.15±0.74)mV,SSa和SSd的包封率均达90%以上;体外释放行为表明VA-SSa/SSd-Lips具有一定的缓释效果;体外溶血性评价表明,SSa和SSd由脂质体包载后溶血毒性显著降低;VA-SSa/SSd-Lips的SSa和SSd药时曲线下面积(area under the curve,AUC)分别是SSa/SSd溶液的1.53(SSa)倍和1.99(SSd)倍,生物利用度显著提高;VA-SSa/SSd-Lips的t1/2 分别是SSa/SSd溶液的2.46(SSa)倍和 3.19(SSd)倍,SSa/SSd-Lips的t1/2分别是柴胡皂苷a和柴胡皂苷d混合溶液(SSa/SSd-Sol)组的0.89(SSa)倍和 1.25(SSd)倍.VA-DiR-Lips在活体成像中具有良好的肝脏靶向性能.结论 本研究设计并构建的VA修饰脂质体VA-SSa/SSd-Lips的粒径、包封率、载药量及体内外释药行为均达到了本文的设计目的.
Preparation and in Vitro Drug Release Evaluation of Vitamin A-modified Saikosaponin a/d Liposomes
Objective Preparation of vitamin A(VA)-modified Saikosaponin(SS)a and SSd targeted liposomes and investigation of their ex vivo drug release behavior.Methods Based on the optimal ratio of soy phospholipid CS-95,cholesterol succinyl monoester 4-[(3β)-Cholest-5-en-3-yloxy]-4-oxobutanoic acid(CHEM)and targeting ligand(DSPE-PEG-VA),the drug delivery system of VA-modified SSa/SSd liposomes was constructed by coating SSa/SSd by thin-film dispersion sonication and then piggybacking DSPE-PEG-VA on liposomes in combination with post-insertion method,using encapsulation rate as the index(VA-SSa/SSd-Lips).Transmission electron microscopy(TEM)and dynamic light scattering were used to determine the liposome morphology,particle size and potential.Fisetin precipitation was used to investigate the liposome encapsulation rate and drug loading.2%rabbit erythrocyte suspension was used to investigate the hemolysis of VA-SSa/SSd-Lips.Normal rats were injected with tail vein(1 mg/kg)VA-SSa/SSd-Lips solution,SSa/SSd-After injection of VA-SSa/SSd-Lips solution,SSa/SSd-Lips solution and SSa/SSd solution into the tail vein of normal rats,blood was collected from the orbits at different time points,and the drug concentrations of SSa and SSd in the plasma of rats at each time point were determined,and pharmacokinetic parameters were calculated using DAS 3.0 software;the in vivo fluorescence distribution of VA-DiR-Lips after tail vein injection in nude rats was observed by small animal live imager.Results The average particle size of VA-SSa/SSd-Lips was(142.43±0.60)nm,PDI was(0.31±0.052),zeta potential was(-14.15±0.74)mV,and encapsulation rate of both SSa and SSd reached more than 90%;in vitro release behavior indicated that VA-SSa/SSd-Lips had some slow release effect;in vitro The in vitro release behavior indicated that VA-SSa/SSd-Lips had a slow release effect;the in vitro hemolytic evaluation showed that the hemolytic toxicity of SSa and SSd was significantly reduced after encapsulation by liposomes;the area under the drug-time curve(Area under the curve,AUC)of SSa and SSd of VA-SSa/SSd-Lips was 1.53(SSa)and 1.99(SSd)times that of SSa/SSd solution,respectively,and the bioavailability was significantly improved;the t1/2 was 2.46(SSa)and 3.19(SSd)times higher than that of SSa/SSd solution,respectively,and the t1/2 of SSa/SSd-Lips was 0.89(SSa)and 1.25(SSd)times higher than that of SSa/SSd-Sol group,respectively.VA-DiR-Lips has good liver targeting performance in live imaging.Conclusion The particle size,encapsulation rate,drug loading capacity and ex vivo drug release behavior of the VA-modified liposomes VA-SSa/SSd-Lips designed and constructed in this study achieved the design objectives of this paper.