Search results for "LECITHIN"
showing 10 items of 61 documents
Extraction of amino acids with emulsion liquid membranes using industrial surfactants and lecithin as stabilisers
2000
Abstract Industrial surfactants (being the mixtures of several individual compounds) were used as stabilisers of emulsion liquid membranes (ELMs). Although, some impurities present in technical formulations of these compounds were extracted to aqueous solutions of amino acids, most of the used surfactants well served to this purpose. In the case of amino acid transport, they do not act as carriers and application of additional carrier (such as D2EHP) was required in order to facilitate the transport. Interestingly, the same properties were found for lecithin, industrially important natural surfactant. Lecithin applied as a chiral discriminator, used either as an emulsion stabiliser or carri…
H-NMR and FT-IR study of the state of melatonin confined in membrane models: location and interactions of melatonin in water free lecithin and AOT re…
2004
The state of melatonin confined either in dry lecithin or bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) reversed micelles has been investigated by H-NMR and FT-IR spectroscopies as a function of the melatonin to surfactant molar ratio (R). The analysis of experimental results leads to hypothesize that, independently of R and the surfactant nature and as a consequence of anisotropic melatonin/surfactant interactions, melatonin is totally solubilized in reversed micelles and mainly located by opportune orientation in the nanodomain constituted by the surfactant head groups. The absence of significant spectral changes related to the protons linked to the first carbon atoms of surfactant a…
Phospholipid-based reverse micelles.
1990
Physicochemical investigations on the aggregation of phospholipids (mainly phosphatidylcholines) in organic solvents are reviewed and compared with the aggregation behaviour of phospholipids in aqueous medium. In particular we review the data showing that phosphatidylcholines (lecithins) form reverse micellar structures in certain apolar solvents. In these systems not only low molecular weight compounds but also catalytically active enzymes and entire cells can be solubilized. In addition, highly viscous phosphatidylcholine gels can be obtained in organic solvents upon solubilizing a critical amount of water. Generally, phospholipid-based reverse micelles can be regarded as thermodynamicall…
Structural Investigation of Water/Lecithin/Cyclohexane Microemulsions by FT-IR Spectroscopy
1995
Abstract FT-IR spectra of water/lecithin/deuterated cyclohexane microemulsions as a function of water/lecithin molar ratio R ( R = [water]/[lecithin]) at various volume fractions ( O ) of the micellar phase have been recorded at 25°C. After elimination of the small spectral contributions due to deuterated cyclohexane and normalization, the shape of the C–H stretching band due to lecithin has been found dependent upon R and O whereas that of the O–H stretching band has been found dependent only upon R . The change in shape of the C–H band was interpreted in terms of a modification of the lecithin alkyl chain packing order. The analysis of the O–H band provides evidence that the hydroxylic gr…
Effects of different emulsifiers and refining time on rheological and textural characteristics of compound chocolate
2018
The purpose of this study was to investigate the possibility of producing reduced fat dark compound chocolate in the ball mill refiner and using some selected emulsifiers. The effects of selected emulsifiers including lecithin, Polyglycerol polyricinoleate (PGPR) and citrem in two levels and two refining times on the characteristics such as moisture, particle size, hardness and rheological properties of the samples was examined. Data analysis revealed that the Casson model was appropriate to describe the rheological behavior of the samples containing lecithin and citrem; however, Power law model was appropriate for the samples containing PGPR. The results showed that citrem is the most effe…
Localization and interactions of melatonin in dry cholesterol/lecithin mixed reversed micelles used as cell membrane models
2005
The state of melatonin confined in dry cholesterol/lecithin mixed reversed micelles dispersed in CCl4 was investigated using 1H-NMR and FT-IR spectroscopies as a function of the melatonin to lecithin molar ratio (R(MLT)) and of the cholesterol to lecithin molar ratio (R(CHL)). An analysis of experimental results leads to the hypothesis that, independent of R(MLT) and as a consequence of anisotropic melatonin/lecithin, melatonin/cholesterol and cholesterol/lecithin interactions, melatonin is totally solubilized in reversed micelles. Melatonin is mainly located in and oriented in the nanodomain constituted by the hydrophilic groups of cholesterol and lecithin. A competition of melatonin and c…
Mixtures of lecithin with polymerizable derivatives of cholesterol. A monolayer film balance study.
1986
One of the best investigated binary lipid mixtures is the lecithin-cholesterol system. We show here that it is possible to modify the cholesterol in such a way that it can be polymerized without changing its behaviour in mixtures with lecithin. The polymerizable derivatives exhibit a very similar phase diagram in the mixture with dipalmitoyl-phosphatidylcholine as the cholesterol itself. This is demonstrated by filmbalance measurements.
Dielectric properties of water/lecithin/cyclohexane gels
1993
Dielectric relaxation measurements in the frequency range 0.1–15 GHz have been carried out on water/lecithin/cyclohexane gels using a time domain reflectometry method (TDR). Dielectric dispersions describable in terms of a power law typical of percolated systems, but with exponents significantly different from those characterizing statically or dynamically percolated systems are observed. The dielectric dispersions, attributed to water and/or lecithin head group rotational motions, indicate that these motions are characterized by a wide spectrum of relaxation times.
Liposomes modified by mono- and bis-phthalocyanines: A comprehensive EPR study.
2016
The impact of selected metallophthalocyanines, featuring diverse molecular structure, upon the fluidity of liposome membranes was studied using the spin label EPR technique. The “mono”-type MPc’s (M = Zn, Sn; Pc = C32H16N8 is the phthalocyanine ligand) and sandwich LnPc2 complexes (Ln = Nd, Sm, Gd) were explored. Liposomes were obtained in a sonication process, from egg yolk lecithin (EYL) in water. TEMPO and 16-DOXYL spin labels were used to monitor the peripheral and central part of the lipid double layer, respectively, which allowed to localize the phthalocyanine additive within the bilayer, as well as to perform independent measurements of changes in fluidity upon addition thereof. All …
Study of lecithin reverse micelles by FT-IR spectroscopy
2007
FT-IR spectra of water/lecithin/deuterated cyclohexane microemulsions as a function of water/lecithin molar ratio R (R=[water]/[lecithin]) at various lecithin volume fractions (φ) have been recorded. After elimination of the spectral contributions due to the deuterated cyclohexane and normalization, the band parameters of the CO and PO4 vibrational modes due to lecithin have been found dependent only upon R. This behaviour has been interpreted in terms of a progressive structural modification of the water/lecithin interface superimposed to the progressive hydration of CO and PO4 groups. Moreover, no correlation between the CO and PO4 band parameters and the formation of gel-like micellar so…