熊果酸纳米粒的乳化溶剂蒸发制备工艺、表征及溶出特征

Preparation, characterization, and dissolution characteristics of ursolic acid nanoparticles prepared by emulsion solvent evaporation method

目的优化熊果酸纳米粒(ursolic acid nanoparticles,UANs)的制备工艺,对其进行表征,并考察其溶解度和溶出速率的改善情况。方法采用乳化溶剂蒸发法,以氯仿-乙醇(7∶3)为有机相、超纯水为水相、泊洛沙姆188为表面活性剂和冻干保护剂制备UANs。利用单因素实验筛选制备UANs的最优条件,并以粒径大小作为单因素实验的考察条件。影响UANs粒径大小的因素包括表面活性剂浓度、有机相与水相的体积比、匀浆速度和匀浆时间、均质压力和均质次数。利用激光粒度仪、扫描电镜(SEM)、X射线衍射(XRD)和差示扫描量热法(DSC)对UANs进行表征。并就熊果酸(UA)原粉和UANs冻干粉的饱和溶解度和溶出速率进行对比测试。结果制备UANs的最优工艺:泊洛沙姆188的质量分数为0.05%,有机相和水相的比为1∶4,匀浆速度为7 000 r/min,匀浆时间为2 min,均质压力为50.0 MPa,均质次数为6次。在最优条件下制备UANs的粒径为(157.5±28.0)nm,电位为(20.33±1.67)m V。根据粒径正态分布曲线,UANs粒径分布均一;由SEM图像可知,UANs的形态近球形。通过XRD和DSC检测,可以确定纳米粒中UA已转变成无定形态。UANs冻干粉在人工胃液(SGF)、人工肠液(SIF)和去离子水中的饱和溶解度分别是原粉的13.48、11.79和23.99倍。UANs冻干粉在SGF和SIF 2种介质中的溶出速率分别比原粉提高了14.72倍和74.35倍。结论利用乳化溶剂蒸发法制备的UANs改善了UA的水溶性,有利于提高UA的生物利用度。

Objective To prepare and characterize ursolic acid nanoparticles（UANs）, and to investigate its improvement of equilibrium solubility and dissolution rate. Methods UANs were prepared by emulsion solvent evaporation method, and followed by freeze-drying. The organic phase was trichloromethane containing 30% ethanol, the aqueous phase is ultrapure water, poloxamer 188 was as surfactant and cryoprotectant. The optimal conditions for preparing nanoparticles were screened out using single-factor experiment. The particle size was used as the basis for optimization experiment. The following six main parameters had significant influences on particle size were picked out, including the concentration of poloxamer 188, volume ratio of organic to water phase, homogenate speed and homogenate time, as well as homogenization pressure and cycles. And then, dynamic light scattering equipment was used to analyze the mean particle size, the morphology of UANs powder obtained was presented by scan electronic micro-scope（SEM）. The UANs weather and how changes in surface chemical character and physical structure was estimated by using X-ray diffraction（XRD） and differential scanning calorimetry（DSC）. The equilibrium solubility study and dissolution test were carried on raw ursolic acid（UA） and UANs. Results The optimal conditions of preparation UANs： 0.05% of poloxamer 188, 1∶4 of volume ratio of organic to water phase, 7 000 r/min of homogenate speed for 2 min and a homogenization pressure of 50.0 MPa for 6 times. Based on the optimal conditions, the mean particle size was（157.5 ± 28.0） nm and Zeta potential of（20.33 ± 1.67） m V. Particle distribution of UANs illustrated that UA had been nanoscale with uniform particle size distribution. SEM showed that UANs were nearly spherical. By the XRD and DSC, we could acquaint UA in UANs had the same chemical structure as the raw UA but had been amorphous state. The result of solubility test figured that the equilibrium solubility of UANs was 13.48 times in SGF, 11.79 times in SIF and 23.99 times in deionized water than raw UA. The dissolution rate of UANs prepared by ESE method has been up to 14.72 times in SGF and 74.35 times in SIF. Conclusion This study indicates that the emulsion solvent evaporation method has an array of valued on improving water solubility of UA, and it will have benefit on enhancing oral bioavailability.