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phase transition temperature of soy lecithin

5 Different packing adaptations in lamellar mesophases (after Gennis [1989]): At low water contents of egg lecithin, a variety of phases are observable (Fig. 4, where examples of typical molecular shapes, phase arrangements and CPPs are shown for the most prominent phospholipids. Microemulsions Supported by Octyl Monoglucoside and Geraniol. Please reconnect. Development of self-nanoemulsifying tablet (SNET) for bioavailability enhancement of sertraline. This is especially true for highly polydisperse systems where different creaming rates produce enhanced droplet encounter rates [Dickinson and Stainsby, 1988]. Am. Olive Oil Microemulsions:  Enzymatic Activities and Structural Characteristics. Thus, for related reasons to those leading to triply-periodic minimal surfaces (IPMS) in bicontinuous cubic mesophases, foliations of hyperbolic sheets, all parallel to quasi-homogeneous IPMS, describe the orientation of molecules as a function of position in space in blue mesophases. This is also true for the interfacial barrier of lecithin-stabilised O/W emulsions [Hansrani, 1980 / Davis and Hansrani, 1985 / Fisher and Parker, 1988], where various aspects of stability need to be considered. Chem. Indeed, the aggregation processes of (e.g. Structural and Dynamic Properties of Lecithin–Alcohol Based w/o Microemulsions: A Luminescence Quenching Study. Dedicated to the memory of Professor Dr. B. Tamamushi. Nataliya M. Murashova, Liliya A. Prokopova, Ekaterina S. Trofimova, Eugeny V. Yurtov. Though of considerable magnitude, this repulsion is not capable of avoiding long-distance interactions like flocculation [LeNeveu et al., 1976]. However, if the lipids remain crystalline (for example lipid-water mixtures maintained below the Krafft temperature), the resulting aggregate geometries can be strongly influenced by the requirement of nonzero average twist between neighbouring amphiphiles. Vincenzo Vitagliano, Gerardino D'Errico, Ornella Ortona, Luigi Paduano. We use cookies to help provide and enhance our service and tailor content and ads. phases (adapted from New [1990]). 4 0 obj Remarkably, phosphatidylcholine need not be applied in high concentrations, because experience shows that formulations are stable at lower amounts. The shrinking of chain elongation owing to kinks or insertion of double bonds notably also increases the cross sectional area covered by each chain (‘’ in Fig. Very often the preparations are metastable. Like linoleic esters and linoleic glycerides, these dispersions have to be stabilized by antioxidants. Aleksa V. Jovanovic,, Royale S. Underhill,, Tracy L. Bucholz, and. Also, there are references to the use of instant liposomes in combination with carbohydrates as dry powders [1]. Triglyceride-Based Microemulsion for Intravenous Administration of Sparingly Soluble Substances. Franco Pattarino, Emilio Marengo, Michele Trotta, Maria Rosa Gasco. 1). However, it still remains uncertain whether surplus lecithin (assuming an interfacial monolayer) contributes to the stability of the emulsions. BLMs were formed from chromatographically pure lecithin extracted from egg yolk (EYPC). Washington: The Cosmetic, Toiletry, and Fragrance Association, 1996. Helge F. M. Klemmer, Carola Harbauer, Reinhard Strey, Isabelle Grillo, and Thomas Sottmann . Herman [1992] also pointed out that hydrolysis appears at the same rates for sn-1 and sn-2 positions and that subsequent intramolecular acyl migration may let the hydrolysis appear to have taken place at the sn-2 position. Stability of a parenteral emulsion is mainly used in terms of maintaining of its main physical property, namely the dispersed phase particle size distribution. The unsaturated phospholipids that occur naturally in soybeans showed no detectable phase transitions in this temperature range, alone or in combinations. MICHELE TROTTA, ELENA UGAZIO, MARIA ROSA GASCO. We can expect to find a range of similar liquid crystalline phases in protein aggregates, although with significantly smaller lattice parameters (compared with typical protein dimensions). Scheme of a phospholipid molecule. Structure, dynamics and transport properties of microemulsions. Structure of Microemulsions Studied by NMR. 5). For the various lipids contained in lecithin-stabilised emulsions, one would expect lamellar (vesicular) and micellar phases, as well as monolayers at the oil/water-interface. 3). These emulsions successively vanished from the market, although other authors claimed that these toxic effects might be circumvented by further purification of soya lecithin [Mueller and Iacono, 1967]. Structural investigation of lecithin/cyclohexane solutions. Figure 4      Main components of "natural" formulations. Low molecular weight emulsifiers (e.g. When the glucose was added to the cell, an increase in redox current was observed, which was a function of the applied voltage having a maximum at +670 mV. The state of order and the length of the lipophilic tail depends on the conformation of the carbon chains which preferably will be ‘all-trans’ in the case of saturated acyl-chains, since in this case a potential energy minimum occurs. The molecule which has both hydrophilic and lipophilic groups is termed an amphiphile molecule, and includes surfactants, detergents, lipids, cholesterol, bile acids, and similar synthetic molecules. In Intralipid 30® even threefold quantities of oil (30%) are incorporated using 1.2% lecithin, as further reduction of the lecithin/triglyceride ratio was sought. Hansrani [1980], Rabiner et al. ++(e.g., encapsulatedprimrose oil:neurodermatitis), Abbreviations: DMS, derma membrane structure; PC, phosphatidylcholineGenerally, members of the membrane family like liposomes, nanoparticles, and DMS are more compatible with the skin structure than usually applied conventional emulsions. Cartoon illustrating the twist associated with packing of threaded (chiral) screws. Michaela Laupheimer, Thomas Sottmann, Ralf Schweins, Cosima Stubenrauch. In contrast to the hyperbolic layers found in bicontinuous bilayer lyotropic mesophases, the molecules within these chiral thermotropic mesophases are oriented parallel to the layers, to achieve nonzero average twist. Biocompatible Microemulsions and Their Prospective Uses in Drug Delivery. Cosmet Toilet 1997; 112 (7):49-59. Hansrani [1980], Rabiner et al. Find more information about Crossref citation counts. Cholesterol fills in empty spaces among the phospholipids, anchoring them more strongly into the structure. In this case the acyl chains face the outer side of the cylindrical shapes, whereas on the inside the polar groups are located facing a continuous area of water. Taylor. The binary phase diagram of a system of a commercially available purified soybean lecithin and water was determined by X-ray diffraction and polarization microscopy studies. In all cases, glycerol is the isotonicity agent, and sodium hydroxide or sodium oleate are employed to adjust pH to values between 7-8 (according to declaration by some manufacturers) as is desired for large-dose parenterals [Ph.Eur.1997, 1997]. 6 A selection of presently marketed parenteral emulsions in Germany The most favourable relative configuration of identical chiral molecules is that where all neighbouring molecules are twisted relative to each other. [1994] used the heated oil phase as a vehicle for the emulsifier. Chlorpheniramine recovery from aqueous solutions by emulsion liquid membranes using soy lecithin as carrier. Pseudo-ternary Phase Diagrams of Lecithin-based Microemulsions: Influence of Monoalkylphosphates. How the properties of phospholipid-water mixtures and, accordingly, their phase behaviour vary, is summarised in Tab. Furthermore, reduced adsorption of drugs on infusion sets, reduction of local toxicity on infusion [Davis et al., 1985] or reduced drug hydrolysis [Repta, 1981] by incorporation of drugs into parenteral fat emulsions was reported. The phospholipids with 12 or more carbon atoms could self-assemble into closed bilayers called vesicles or liposomes. 4.32. Droplet Structure in Phosphocholine Microemulsions. These so called ‘liposomes’ show diverse size and number of bilayers (lamellae) [New, 1990]. Therefore, glycols like propyleneglycol, glycerol, butyleneglycol, pentyleneglycol, hexyleneglycol, sorbitol and their mixtures are the compounds of choice. By doing so, improved metabolism of triglycerides and their fatty acids and overall better tolerability was reported, making them particularly useful in critically ill patients [Bell et al., 1991 / Sandström et al., 1993 / Dahn, 1995 / Hyltander et al., 1995 / Pscheidl et al., 1995]. Lundberg, B. and Sjöblom, L., Acta Acad. Oil Chemists Soc. Some promising attempts to incorporate this drug into commercial parenteral fat emulsions and thus also lower relatively high nephro-toxicity compared with solubilised drug were reported [Lipp et al., 1993].

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