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1.
2.
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. 相似文献
3.
4.
Tomoko Nii Akira Takamura Kiminori Mohri Fumiyoshi Ishii 《Colloids and surfaces. B, Biointerfaces》2003,27(4):436-332
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. 相似文献
5.
Lecithin/propanol-based microemulsions used as media for a cholesterol oxidase-catalyzed reaction 总被引:1,自引:0,他引:1
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. 相似文献
6.
高效液相色谱法检测保健食品中大豆异黄酮含量 总被引:10,自引:1,他引:10
建立了保健食品中大豆异黄酮的高效液相色谱检测方法 ,通过正交试验法得出保健食品中大豆异黄酮的最佳水解条件为 :盐酸浓度2.0mol/L,酸体积40mL ,水解温度80℃ ,水解时间3h;采用HypersilODS2C18 色谱柱 (250mm×4.6mmID ,5μm) ,流动相为甲醇 -水(体积比47∶53) ,流速1.0mL/min ,检测波长260nm ,柱温40℃ ,线性范围在0.5~96mg/L ,相关系数r为0.999 ,相对标准偏差 (RSD)2.09% ,回收率在98.5 %~100.5 %。 相似文献
7.
Katalin Mészáros Szécsényi I. Esztelecki G. Pokol 《Journal of Thermal Analysis and Calorimetry》2007,89(3):829-833
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. 相似文献
8.
Alessandra Sussulini Jerusa S. Garcia Márcia F. Mesko Diogo P. Moraes Érico M. M. Flores Carlos A. Pérez Marco A. Z. Arruda 《Mikrochimica acta》2007,158(1-2):173-180
Two methods of protein extraction for soybean seeds were evaluated in terms of preservation of the metal ions bound to proteins
after the extraction and separation procedures. The proteins were firstly separated according to their molar masses by polyacrylamide
gel electrophoresis. Then, the protein bands were mapped by synchrotron radiation X-ray fluorescence in order to establish
which metal ions were present in each one. Finally, some mapped protein bands were decomposed by microwave-assisted combustion
and Ca, Cu, K, Mg, Mn, and Zn were quantified by inductively coupled plasma mass spectrometry or inductively coupled plasma
optical emission spectrometry. The extraction methods studied were Method A (based on the treatment of ground soybean seeds with hexane and their extraction with Tris–HCl and β-mercaptoethanol) and
Method B (based on the treatment of ground soybean seeds with petroleum ether and their extraction with Tris–HCl, dithiothreitol,
phenylmethanesulfonyl fluoride, sodium dodecyl sulfate and potassium chloride). The best method was Method B, in which a 78% higher extraction efficiency was obtained when compared to Method A. Additionally, the metal-protein interactions were more appropriately preserved when Method B was applied, where the most affected ions were those that are bound weakly to proteins, such as Ca, K, and Mg. 相似文献
9.
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. 相似文献
10.
Narra Kishore U. M. Dhanalekshmi M. D. Raja Saranya Bhavani 《Journal of Dispersion Science and Technology》2013,34(1):96-102
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. 相似文献