Interactions of native and modified cytochrome C with a negatively charged reverse micellar liquid interface

Native and chemically modified cytochrome C were dissolved in sodium bis(2-ethylhexyl) sulphosuccinate (AOT)-oil-buffer microemulsions. The native cytochrome C contains 19 lysine residues, these groups were modified by 1) acetic anhydride or 2) succinic anhydride. At pH 8.4 the native, acetylated and succinylated proteins carry +8, –3 and –12 elementary charges, respectively. The phase behaviour of the microemulsion systems was found to be highly dependent on the charge of the proteins. Compared to a protein free system the native protein induces a L-2 phase separation at lower temperatures. The acetylated protein has a small effect on the temperature for the phase transition, whereas in the case of succinylated cytochrome C the phase transition takes place at higher temperatures. When dissolved in AOT microemulsions, the native cytochrome C has a perturbed tertiary structure, as indicated by loss of the 695 nm absorption band, while both the modified proteins retain the same optical properties when dissolved in an AOT microemulsion as in a pure buffer solution. The pertubed structure of the native cytochrome C was further investigated by testing the stability of the reduced form of the protein dissolved in the microemulsion media. The native cytochrome is unstable at W > 10, whereas the two modified proteins were found to be stable at all W-values investigated. The average location of the three proteins was determined by pulse radiolysis. The quenching rate constant of the hydrated electron depends upon the location of the probe in the reverse micelle; the succinylated protein is localised in the aqueous core of the reverse micelles, but both the native and the acetylated forms were found to be localised close to or at the AOT interface.     

Perfluoroalkylated derivatives of 6-deoxy-6-ethylamino-d-galactose, 1-deoxy-1-methylamino-d-glucitol, and 1-amino-1-deoxy-d-glucitol: syntheses, hemocompatibility, and effect on perfluorocarbon emulsion

N-Polyfluoroalkyl derivatives of 6-deoxy-6-ethylamino-1,2;3,4-di-O-isopropylidene-α-d-galactopyranose (8-10), 1-deoxy-1-methylamino-d-glucitol (13-15), and 1-amino-1-deoxy-d-glucitol (16-18), all possessing perfluoroalkyl segment, were prepared using nucleophilic epoxide ring opening of 2-[(perfluoroalkyl)methyl]oxiranes 1-3. Co-emulsifying properties and hemolytic activity of the new perfluoroalkylated amphiphiles were tested. Both types of the polyol derivatives 8-10 and 13-18 generally displayed good to excellent co-emulsifying properties on testing on perfluorodecalin/Pluronic F-68 microemulsions. Mono-perfluoroalkylated compounds 8-10 and 13-15 displayed high hemolysis, whereas acyclic bis-perfluoroalkylated compounds 16-18 were non-hemolytic even for short perfluorobutyl segment (16). The properties were generally improving with increasing perfluoroalkyl chain length.     

Amphiphiles for supercritical CO2

A semi-fluorinated hybrid amphiphile, pentadecafluoro-5-dodecyl (F7H4) sulfate, has been shown to form reversed micelles in dense CO₂; the aggregates evolve to form water-in-CO₂ (w/c) microemulsion droplets on addition of water. Aggregation structures in these w/c phases have been characterised by small-angle neutron scattering (SANS), showing the presence of cylindrical droplets, which change into dispersed lamellar phases at even higher water loadings. Other systems are also introduced, being high internal phase emulsions (HIPEs) with brine, and liquid and supercritical CO₂, stabilized by certain commercially available nonylphenol ethoxylates (Dow Tergitol NP-, and Huntsman Surfonic N- amphiphiles). These dispersions have been characterised by SANS for the first time. Quantitative analyses of the HIPEs SANS profiles show that they behave similarly to hydrocarbon-water emulsion analogues, with regard to total interfacial areas and the effects of amphiphile concentration on the underlying structures. Finally, the advantages and disadvantages of both approaches for controlling the physico-chemical properties of liquid/supercritical CO₂ in potential applications are compared and contrasted. These results highlight the importance of using specially designed CO₂-philic amphiphiles for generating self-assembly structures in dense CO₂.     

Enhanced activity of Mucor javanicus lipase in polyoxyethylene sorbitan trioleate containing microemulsion-based organogels

The efficacy of polyoxyethylene sorbitan trioleate (Tween 85) addition on the activity of Mucor javanicus lipase was investigated in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) microemulsion-based organogels (MBGs). Gelatin was used as the gelling component of the MBGs. The maximal reaction rate was obtained at an AOT:Tween 85 molar ratio of 10:1. Under a fixed molar ratio system of AOT:Tween 85 = 10:1, the reaction rate also attained a maximum at a W_G (=[H₂O]/[AOT + Tween 85] in MBG phase) value of 100 and an AOT concentration of 150 mM. The reaction proceeded under a reaction-controlled regime, and the reaction rate for the AOT/Tween 85 mixed system was about 2-fold higher than that for the AOT single system. The lipase activity was well maintained for 10 days and recovered by contacting the MBGs with concentrated amphiphile solutions.     

丁香花蕾油作为微乳的油相促进黄芩苷透皮吸收的研究

目的:黄芩苷作为黄芩的主要成分之一,其制剂虽应用广泛,但存在较多缺点,如水溶液不稳定、口服吸收差、生物利用度不高及药物体内半衰期短等从而导致用药剂量大且频繁给药。本文目的是研究丁香花蕾精油及其微乳对黄芩苷体外经皮渗透性的影响。方法:采用Valia-Chien扩散池,以生理盐水为接受液,不同浓度的丁香花蕾精油以及以丁香花蕾精油作为微乳的油相及促进剂进行大鼠离体皮肤的体外渗透实验。结果:黄芩苷微乳的平均粒径为41.3±5.1 nm,多分散指数为0.18,表明该制剂粒径小且均一。微乳(不含丁香花蕾精油)、丁香花蕾精油及含丁香花蕾精油的微乳对黄芩苷均有不同程度的增渗作用。其中,含丁香花蕾精油的微乳对黄芩苷的促渗作用最强。结论:丁香花蕾精油以及以丁香花蕾精油作为微乳的油相对黄芩苷均有一定的促进渗透作用。     

Singlet oxygenation in microemulsion catalysed by vanadium chloroperoxidase

Non-ionic microemulsions compatible with the enzyme vanadium chloroperoxidase were designed to perform singlet oxygenation of apolar substrates. The media were based on mono- and polydisperse ethoxylated fatty alcohols (C_iE_j), octane and aqueous buffer. “Fish” diagrams were determined to identify the Winsor-boundaries and to formulate a monophasic Winsor IV microemulsion with a minimal surfactant concentration, ensuring less singlet oxygen (¹O₂) loss than in an aqueous system, thus creating a high oxygenation efficiency. The enzyme was shown to be fully stable in the microemulsion for at least 10 h, converting H₂O₂ into a constant flow of ¹O₂ in the aqueous microdomains. Part of the ¹O₂ diffuses into the organic compartments prior to fast physical deactivation of ¹O₂ by water molecules. In the apolar domains ¹O₂ quantitatively converts the model substrate 9,10-dimethylanthracene into its corresponding endoperoxide. Near-IR chemiluminescence measurements confirm that the ¹O₂ signal in the microemulsion is higher than in simple aqueous buffer. In a well-stirred (water/octane) biphasic system endoperoxide formation is also observed but the conversion rate is much lower, most likely due to stronger physical quenching of ¹O₂.     

Microemulsion electrokinetic chromatographic analysis of some polar compounds

This study presents the optimization of a microemulsion electrokinetic chromatographic (MEEKC) electrolyte solution by using UV detection and with the method, simultaneous separations of chemically, biochemically and pharmaceutically related anionic and cationic compounds. Representatives of the compound groups were from isoflavonoids, benzodiazepines, metanephrines, diuretics and peptide hormones. The MEEKC separations under basic conditions were first optimized using a two-component isoflavonoid mixture as the sample and an electrolyte containing 10 mM tetraborate as the main buffer (pH 9.5). The stable microemulsion phase was adjusted with various amounts of octane, 1-butanol and sodium dodecyl sulfate (SDS). An only acidified electrolyte solution used in the study was made of phosphoric acid (pH 1.8) containing octane, SDS and ethyl acetate. The analyses with isoflavonoids showed that electrophoretic mobilities of the investigated compounds were highly related to the concentrations of SDS and 1-butanol with linear and parabolic correlation, respectively. However, addition of octane gave linear correlation only at low concentrations. In most cases four to six structurally related compounds and even 13 diuretics with various polar properties were separated from each other in basic microemulsion medium. The acidified MEEKC electrolyte gave good resolution for anionic metanephrines.     

黄芪决明子微乳对综合因素复制的脂肪肝大鼠的影响研究

目的:研究黄芪决明子微乳(ACM)对脂肪肝大鼠的防治作用,并进行相关机理探讨.方法:采用高脂饮食饲养,灌服酒精及注射小剂量四氧化碳制备大鼠脂肪肝模型,同时给予ACM制剂进行治疗.通过检测血清TC,TG,LDL-C,HDL-C,ALT,AST等指标及肝组织中TC,TG含量,肝组织SOD活性,MDA含量等各项指标,观察肝组织病理学变化,从而考察不同剂量ACM对大鼠脂肪肝的防治作用.结果:ACM能明显改善脂肪肝大鼠肝组织病理学表现,减轻肝脂变程度;降低的血清中ALT的含量;显著升高血清HDL-C含量,降低血清TC,LDL-C,VLDL-C含量;降低肝组织TC,TG含量,降低肝组织MDA含量,增强肝组织SOD活性.结论:ACM对大鼠脂肪肝有良好的防治作用,防治机理与其具有调节血脂,降低肝脂,改善肝功能,增强肝脏抗氧化,清除肝毒性物质等作用相关.     

Nutrient broth/PEG200/TritonX114/Tween80/Chloroform microemulsion as a reservoir of solubilized sitosterol for biotransformation to androstenedione

Microemulsions (ME) can act as a reservoir of solubilized hydrophobic substrates. The biotransformation of hydrophobic sitosterol to androstenedione (AD) with MEs prepared from nutrient broth and PEG 200 (1:1) as aqueous phase, 40 g/l sitosterol dissolved in chloroform as organic phase, Triton X114 and Tween 80 (1:1) as surfactant phase, was investigated. The phase behavior of this system was studied for ten different ratios(w/w), 10:0, 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, 1:9 and 0:10 of the organic phase and surfactant at 30 °C. A pseudoternary phase diagram was constructed to demarcate the region giving stable MEs. The maximum solubility of sitosterol in ME medium was observed to be 8 g/l, which is 3 orders of magnitude higher than the reported sitosterol solubility of 2–4 mg/l in aqueous medium. The ME medium was used for biotransformation studies and a comparative result has been reported. Transmission electron microscopy of cells grown in ME having oil, surfactant and aqueous phase in the ratio of 6:14:80 showed a weakened cell wall structure that permitted production of 465.86 mg/l AD.     

Optimization of the microemulsion formulation of curcuma oil and evaluation of its acaricidal efficacy against Tetranychus cinnabarinus (Boisduval) (Acari: Tetranychidae)

The microemulsion formulation (hereafter formulation) of curcuma oil and its acaricidal efficacy against Tetranychus cinnabarinus Boisduval (Acari: Tetranychidae) were optimized in the laboratory to evaluate their spray effectiveness of oviposition inhibition and repellence. Ethovision XT6 was used to analyse the effects of the sublethal concentrations (LC₂₀) of curcuma oil and the formulation on the behaviors of T. cinnabarinus. The results showed that Tween-80 was the best surfactant, Isopropanol was the best co-surfactant and K_m = 2:1 was the best condition for the formulation. The prepared microemulsions are stable under conditions of centrifugation and incubation for extended periods. The results showed that the effect of the spray bioassays of the formulation against T. cinnabarinus continuously increased during the experiment, but for curcuma oil almost no longer increase observed when the exposure time went beyond 24 h. Moreover, compared with curcuma oil (LC₅₀ = 0.716%), the spray bioassay of the formulation (LC₅₀ = 0.035%) was stronger against T. cinnabarinus. The repellency of the formulation to T. cinnabarinus was stronger with increasing exposure time, but that of curcuma oil declined after 12 h of exposure. The mobile distance of T. cinnabarinus treated with the formulation continuously declined during the experiment but that due to the curcuma oil almost no longer declined when the treatment time reached 12 h. The maximum mobile frequency of T. cinnabarinus treated by curcuma oil and the formulation was recorded at 6 h and 12 h, respectively. Thus, the formulation is a promising candidate as a botanical acaricide of green vegetables.