Lecithin salts

These tricomplex flocculations are really the simplest of those discussed so far because beside the amphoion only those ions are added which occur essentially in the tricomplex. With all the others we had, besides the amphoion, four ions, namely two cations, two anions. That is two too many, which thus can only have in principle a suppressive action. It is probable for these reasons that in Table I (p. 422) where we have investigated egg lecithin + salt I -f- salt II there was no evidence for the existence of the tricomplexes egg lecithin + Ca + CNS or egg lecithin H- Ca -j- I. 

Lecithins are fatty acid esters of glycero-phosphoric acid derivatives. Commercially glycerophosphoric acid is used to prepare the medicinal glycerophosphate salts, c.g. the calcium salt. 

Commercial lecithin is insoluble but infinitely dispersible in water. Treatment with water dissolves small amounts of its decomposition products and adsorbed or coacervated substances, eg, carbohydrates and salts, especially in the presence of ethanol. However, a small percentage of water dissolves or disperses in melted lecithin to form an imbibition. Lecithin forms imbibitions or absorbates with other solvents, eg, alcohols, glycols, esters, ketones, ethers, solutions of almost any organic and inorganic substance, and acetone. It is remarkable that the classic precipitant for phosphoHpids, eg, acetone, dissolves in melted lecithin readily to form a thin, uniform imbibition. Imbibition often is used to bring a reactant in intimate contact with lecithin in the preparation of lecithin derivatives. 

Other Reactions of Phospholipids. The unsaturated fatty acid groups in soybean lecithin can be halogenated. Acetic anhydride combined with the amino group of phosphatidylethanolamine forms acetylated compounds. PhosphoHpids form addition compounds with salts of heavy metals. Phosphatidylethanolamine and phosphatidjhnositol have affinities for calcium and magnesium ions that are related to interaction with their polar groups. 

An earlier procedure for the production of choline and its salts from natural sources, such as the hydrolysis of lecithin (23), has no present-day apphcation. Choline is made from the reaction of trimethyl amine with ethylene oxide [75-21-8] or ethylene chlorohydrin [107-07-5J. 

Anilinonaphthalenesulfonic acid ammonia salt (ANS reagent) fatty acids [112,113] lecithin/sphingomyelin [114, 115] cholesterol and its esters [116, 117] steroids, detergents, hydrocarbons [118,119] prenol, prenylquinones [120]... 

In media selective for enterobacteria a surface-active agent is the main selector, whereas in staphylococcal medium sodium and lithium chlorides are the selectors staphylococci are tolerant of salt concentrations to around 7.5%. Mannitol salt, Baird-Parker (BP) and Vogel-Johnson (VJ) media are three examples of selective staphyloccocal media. Beside salt concentration the other principles are the use of a selective carbon source, mannitol or sodium pyruvate together with a buffer plus acid-base indicator for visualizing metabolic activity and, by inference, growth. BP medium also contains egg yolk the lecithin (phospholipid) in this is hydrolysed by staphylococcal (esterase) activity so that organisms are surrounded by a cleared zone in the otherwise opaque medium. The United States Pharmacopeia (1990) includes a test for staphylococci in pharmaceutical products, whereas the British Pharmacopoeia (1993) does not. 

Monoolein will also form the cubic phase together with lecithin (e.g. dioleoyl phosphatidylcholine, see Figure 1), but above about 50% (w/w) lecithin the cubic phase is transformed into the lamellar phase (2). Moreover, water may be replaced by glycerol, completely or partly, in the cubic phase. Vegetable oils, e.g. sesame oil, can be incorporated to some extent (a few percent) in the cubic phase, and the same holds for bile salts. 

The few examples of deliberate investigation of dynamic processes as reflected by compression/expansion hysteresis have involved monolayers of fatty acids (Munden and Swarbrick, 1973 Munden et al., 1969), lecithins (Bienkowski and Skolnick, 1974 Cook and Webb, 1966), polymer films (Townsend and Buck, 1988) and monolayers of fatty acids and their sodium sulfate salts on aqueous subphases of alkanolamines (Rosano et al., 1971). A few of these studies determined the amount of hysteresis as a function of the rate of compression and expansion. However, no quantitative analysis of the results was attempted. Historically, dynamic surface tension has been used to study the dynamic response of lung phosphatidylcholine surfactant monolayers to a sinusoidal compression/expansion rate in order to mimic the mechanical contraction and expansion of the lungs. 

The aggregation behavior of C21-DA salt in dilute electrolyte medium appears to resemble that of certain polyhydroxy bile salts (25,16). That C21-DA, with a structure quite different from bile acids, should possess solution properties similar to, e.g., cholic acid is not entirely surprising in light of recent conductivity and surface tension measurements on purified (i.e., essentially monocarboxylate free) disodium salt aqueous solutions, and of film balance studies on acidic substrates (IX) The data in Figure 3 suggest that C21-DA salt micelles Incorporate detergents - up to an approximate weight fraction of 0.5 -much like cholate Incorporates lecithin or soluble... 

The addition of absorption enhancers, like bile salts (glycocholate), fatty acids (Unoleic acid), surfactants (lecithins, polyoxyethylene-9-lauryl ether or N-lauryl-P-D-maltopyra-noside) and chelators (EDTA) can significantly increase the absorption of various proteins. However, the application of enhancers is limited by their toxicity. For example polyoxyethyl-ene-9-lauryl ether and sodium glycocholate caused serious oedema, haemorrhage and inflammation of the lung after intratracheal instillation [39]. 

Note Examples are potassium salts of unbranched alkanoic acids, lecithin, certain polyisocyanates, cellulose derivatives with side-chains, such as (2-hydroxypropyl)cellulose, and cyanobiphenyl derivatives of alkyl(triethyl)ammonium bromide. 

NA Mazer, GB Benedeck, MC Carey. Quasielastic light-scattering studies of aqueous biliary lipid systems. Mixed micelles formation in bile salt-lecithin solutions. Biochemistry 19 601-615, 1980. 

K Muller. Structural aspects of bile salt-lecithin mixed micelles. Hepatology 4 134S-137S, 1984. 

P Schurtenberger, NA Mazer, W Kanzig. Micelle-to-vesicle transition in aqueous solution of bile salt and lecithin. J Phys Chem 89 1042-1049, 1985. 

MA Schwarz, K Raith, HH Ruettinger, G Dongowski, RHH Neubert. Investigations of interactions between drugs and mixed bile salt/lecithin micelles—a characterization by micellar affinity capillary electrophoresis. Part III. J Chro-matogr A 781 377-389, 1997. 

When mesophase, that is, liquid crystal, consisting of three components of bile salt, lecithin and cholesterol was produced, deposition of calcium salts of bile acids was observed on the cholesterol disk surface. The relation between mesophase formation and calcification will be elucidated in this paper. 

Miller et al have reported that in bile salt solutions in the presence of EL, if the EL concentration is less thcin half of that of the bile salts, the mixed micelle shape beccmes spherical, but, otherwise, the shape is a disk as shown in Figure 2. All solutions used here inclixie 32 mM lecithin and 100 mM total bile salts, therefore the micelle shape in all systems here must be spherical. Edward et al... 

Figure 2 The mixed micelles consisting of Bile salts and Lecithin. Disk Excess Lecithin. Sphere Excess Bile salts.

The vesicular size might go back reversiblly to the original one in the case of nonionic vesicles (Figures 9 and 10) for which the present removal rate may be too slow. A similar behavior was reported by Schurtenberger et al. for their lecithin-bile salt systems vesicle size is reduced to the original dimension after dialysis of remains large when the solubilized is diluted with the buffer solution to very fast reduction of bile salt fast removal of bile salt(22) ... 

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