Spreading of dipalmitoyl phosphatidylcholine on the surface of sodium deoxycholate aqueous solution

The surface pressure vs. mokcular surface area relations for dipalmitoyl phosphatidylcholine (DPPC) insoluble monolayer and sodium deoxycholate (SDC) adsorbed monolayer,L and D1, respectively, were obtained from the analyses of surface tensions measured by the Wilhelmy glass plate. Also, D1 was obtained by a drop-weight method. Next, the surface pressure time course,(t), of the SDC aq. was measured by the Wilhelmy plate before and after DPPC was spread on the liquid surface. At DPPC spreading,(t) jumped to a maximum,, and decreased along an exponential curve. The values of with various surface amounts of DPPC and bulk concentrations of SDC were analyzed using a dual surface-region model. The model enabled the estimation of. For better fitting, modified relations were constructed in place of D1. The exponential decrease of(t) was also observed on the SDC adsorbed monolayer which was rapidly compressed by a moving barrier. The(t) relaxation rate constants of the SDC monolayers which were compressed by DPPC spreading and the moving barrier agreed with each other, suggesting a desorption of SDC from the surface.     

Factors affecting physicochemical properties of liposomes prepared with hydrogenated purified egg yolk lecithins by the microencapsulation vesicle method

We examined hydrogenated purified egg yolk lecithins, having practical advantages over non-hydrogenated ones, as liposomal membrane materials. Liposomes were prepared by the microencapsulation vesicle (MCV) method in which liposomes are formed through two-step emulsification and dispersion. Three types of purified egg yolk lecithins with different iodine values were examined after being dissolved in one of three lipid solvents. The liposome size increased as the temperature during the second emulsification increased, being closer to the boiling temperature of the solvent. The preparation temperature in relation to the transition temperature of each lecithin was also a factor affecting liposome sizes. As for the encapsulation efficiencies of the model compound calcein in liposomes, they differed mainly depending on the solubility of each lecithin in a lipid solvent and it was more obvious in hydrogenated lecithins. A high preparation temperature resulted in lower encapsulation efficiencies, suggesting that leakage of encapsulated calcein was facilitated at high temperature in the MCV methods. There was a significant correlation between liposome sizes and encapsulation efficiencies in non-hydrogenated purified egg yolk lecithin but not in hydrogenated ones. When using hydrogenated purified egg yolk lecithins as liposomal membrane materials, it was suggested that a lipid solvent should be chosen so that a lecithin completely dissolves under the preparation condition in order to achieve a higher encapsulation efficiency. Smaller liposome particles were obtained when the second emulsification was performed at a lower temperature compared with the boiling point of the lipid solvent. These findings can be applied to control encapsulation efficiencies and particle sizes in each particular liposome preparation enclosing therapeutic agents.     

Lecithin/propanol-based microemulsions used as media for a cholesterol oxidase-catalyzed reaction

Reverse micelles, Winsor III and IV systems were examined as reaction media for the enzymatic conversion of cholesterol to cholestenone by cholesterol oxidase at 298.2 K. The micelles and the microemulsions, stabilized by soybean lecithin and ethanol or 1-propanol as cosolvent, were characterized with respect to phase behavior and distribution of 1-propanol between the phases of the Winsor III systems. The used oils were dodecane, tetradecane, and hexadecane. The Winsor IV systems and the surfactant-rich phase in the Winsor III systems exhibit bicontinuous structures. The reaction yield for the enzymatic conversion performed in a Winsor IV system was much higher than in a Winsor III system or in reverse micelles.     

Adventages and limits on usage of thermal methods in complex systems

In order to increase the nutrition value of bread, one of the most commonly used foodstuff all over the world, different additives are used in bread processing. In this paper we describe the thermal changes in bread and that of with 0.5% crude soybean lecithin additive. Their thermal stability has been investigated by TG, DSC and EGD methods. The thermal changes were also followed of soy products, lecithin and lysine, ingredients used as bread additives in order to check if they may suffer any thermal degradation during the baking process. The data obtained can be of use only for qualitative conclusions. According to the obtained data at the usual bread baking temperature only the additives in crust may partly decompose while in the crumb, at lower temperatures the additives, due to baking, are not damaged. The thermal methods give a possibility for rapid estimation of processes induced by heat effects in additives during the baking, and they are suitable to detect the changes during the bread-making procedure. However, they are neither suitable to provide any quantitative data on these changes nor facts affecting the nutrition value and of the bread.     

蚯蚓冻干粉对高血脂小鼠胆固醇逆转运相关基因的调节作用

以高脂饲料饲喂昆明种小鼠构建高血脂小鼠模型,灌胃给予高、中、低剂量(0.4,0.2,0.1g/kg)蚯蚓冻干粉,每天1次,同时饲喂高脂饲料,以仅饲喂高脂饲料组小鼠为对照,共饲养10周.提取小鼠肝脏总RNA,应用半定量RT-PCR技术检测实验组与对照组小鼠胆固醇逆转运相关基因卵磷脂胆固醇酰基转移酶(lecithin cholesterol acyltransferase,LCAT)和脂蛋白酯酶(lipoprotein lipase,LPL)mRNA表达水平.结果表明,蚯蚓冻干粉极显著提高实验组小鼠LCAT mRNA表达水平(P0.01),显著提高LPL mRNA表达水平(P0.05),提示这是蚯蚓冻干粉能够降低高血脂小鼠血浆胆固醇水平的原因之一.     

维生素K1磷脂/胆盐混合胶束的制备及体外评价

制备维生素K1磷脂/胆盐混合胶束(VK1 MMS),并进行体外评价。用薄膜分散-超声法制备维生素K1磷脂/胆盐混合胶束。通过单因素考察,对蛋黄卵磷脂(EPC)/甘氨胆酸钠(BS)的比例、胆盐浓度、超声时间进行筛选优化,测定维生素K1磷脂/胆盐混合胶束的粒径、形态;并分别考察混合胶束考察与0.9%氯化钠注射液或5%葡萄糖注射液的稀释稳定性。当胆盐浓度为55 mg/m L,磷脂/胆盐质量比为1,超声温度为40℃时,维生素K1磷脂/胆盐混合胶束的载药量达到5 mg/m L;混合胶束平均粒径为20.9 nm,形态为类球体,具有良好的稀释稳定性。维生素K1混合胶束的制备工艺简单方便、载药量高、粒径分布理想、稳定性好,可用于开发静脉注射制剂。     

卵磷脂抗石英毒作用的研究

本文采用家兔肺泡巨噬细胞(AM)体外培养法,以细胞内游离钙浓度([Ca~(2+)]_i)、细胞存活率、乳酸脱氢酶(LDH)和酸性磷酸酶(ACP)活性为指标,观察了卵磷脂、脑磷脂及现用防治硅肺药物克矽平(PVPNO)、柠檬酸铝等抗石英毒效果。结果表明:卵磷脂在所试各药物中效果最佳.初步探讨了卵磷脂拮抗石英细胞毒性的机理.卵磷脂有成为防治硅肺药物的可能性.     

Design and In Vitro Evaluation of Solid-Lipid Nanoparticle Drug Delivery for Aceclofenac

Solid-lipid nanoparticles (SLNs) are an interesting nanoparticulate delivery system. The present work was carried out with the aim to develop a prolonged release solid-lipid nanoparticulate system for the drug using aceclofenac. Aceclofenac-loaded solid-lipid nanoparticles (ACSLNs) was prepared by hot high pressure homogenization technique. Tripalmitin was used as the lipid core. Surfactants (Poloxamer 188, Tween 80, and soya lecithin) and co-surfactant (sodium tauro glycholate) were used in the formulations. The prepared ACSLN formulations were characterized for encapsulation efficiency (EE), photon correlation spectroscopy (PCS), scanning electron microscopy (SEM), and x-ray diffraction (XRD). From these studies, mean particle diameter of the formulation prepared with combination of surfactants (Poloxmer 188 and Tween 80) was about 200 nm with spherical morphology and amorphous nature. Higher EE was obtained with SLNs prepared using combination of soya lecithin and poloxmer 188. The organization and distribution of the ingredients in the nanoparticulate system were studied by differential scanning calorimetry (DSC) and the results showed that the drug is incorporated into the solid matrix. The prepared formulations demonstrated favorable in vitro prolonged release characteristics. Experimental in vitro release data were substituted in available mathematical models to establish the release kinetics of ACSLNs and it was found to follow first-order kinetics and Higuchi diffusion mechanism. Our results suggest that these SLN formulations could constitute a promising approach for the drug delivery of aceclofenac.     

Effect of Emulsification Method on the Properties of Lecithin‐ and PGPR‐Stabilized Water‐in‐Oil‐Emulsions

Water‐in‐oil (w/o) emulsions were prepared with phosphatidylcholine‐depleted lecithin or polyglycerol polyricinoleate (PGPR) as emulsifying agents. The effect of different laboratory emulsification devices and the effect of sodium chloride on particle size distribution, coalescence stability, and water droplet sedimentation were investigated. The properties of lecithin‐stabilized w/o emulsions were found to depend more strongly on the emulsifying method than those prepared with PGPR. The rotor‐stator system was not suitable for preparing stable w/o emulsions with lecithin. Whereas the addition of salt was essential to achieve coalescence‐stable emulsions prepared with PGPR, the presence of NaCl favored the coalescence of water droplets and phase separation in emulsions containing lecithin.     

BLM成膜液中胆固醇与卵磷脂相互作用的光谱学研究

结合胆固醇与卵磷脂的拉曼光谱,分析了BLM成膜液中胆固醇与卵磷脂的相互作用。得出膜液中胆固醇与卵磷脂的最佳配比为1∶4。室温下,电化学实验的结果表明,以此种比例配置的膜液使膜的稳定性得到提高,导电率减小。