L-a-phosphatidyl choline

The CTI of unsaturated fatty acid residues of a variety of L-a-phosphatidyl-cholines catalyzed by thiyl radicals were studied in alcoholic solutions. POPC (pal-mitoyl oleoyl PC), DOPC (dioleoyl PC), and SAPC (stearoyl arachidonoyl PC), to-... 

L-a-Phosphatidyl choline (lecithin) phospholipid commonly found in plants, but much less so in microorganisms... 

Figure 7. Effect of sample size on apparent molecular weight for soya lecithin phosphatide fractions (conditions same as for Figures 5 and 6 (O) ethanol-soluble fraction (phosphatidyl choline), oligomer GPC (%) ethanol-soluble fraction (phosphatidyl choline), "main column (l ) ethanol-insoluble fraction (other phos-p hat ides), "oligomer GPC (A) ethanol-insoluble fraction (other phosphatides),...

Fig. 5 Surface pressure/area isotherm for the compression cycle of dipalmitoylphos-phatidyl choline (dashed line) and l-palmitoyl-2-(l2-hydroxystearoyl)phosphatidyl choline (solid line) on a pure water subphase at 25°C. Reprinted with permission from Arnett et al., 1989. Copyright 1989 American Chemical Society.

The preformed vesicle (PFV) approach involves incubation of liposomes containing a cationic lipid and a PEG coating with polynucleotides in the presence of ethanol. Typically, LUV composed of distearoyl-phosphatidyl-choline (DSPC), cholesterol (Choi), l-0-(2 -(oi-methoxy-polyethylene-glycol)... 

Encapsulation efficiencies are listed as a function of ethanol concentration for distearoyl-phosphatidyl-choline/choles-terol/l,2-dioleoyl-3-dimethylammoniumpropane large unilamellar vesicle (LUVs). The initial oligonucleotide-to-lipid ratio was 0.034 mol/mol (0.3mg/mg). The LUVs used for these experiments were 99 22 nm in size. The encapsulation values are given as mean SD. 

Figure 2 Encapsulation as a function of ethanol concentration. Oligonucleotides were added to distearoyl-phosphatidyl-choline/cholesterol/l-0-(2 -(co-methoxy-poly-ethylene-glycol)succinoyl)-2-iV-myristoyl-sphingosine /1,2-dioleoyl-3-dimethylam-monium propane liposomes in varying concentrations of ethanol at an initial oligonucleotide-to-lipid ratio of 0.24mg/mg. Abbreviations AS, antisense oligonucleotide %EtOH(v/v), percentage of ethanol in volume/volume.

A series of iomeprol-containing liposomes were evaluated in animals by Petersein et al. [62] and in healthy volunteers by Spinazzi et al. [63,64]. BR2 and BR21 are liposomes made of phosphatidyl choline (PC),dipalmitoyl phospatidic acid (DPPA) and cholesterol at a molar ratio of 2 1 (PC -i- DPPA/cholesterol) with an iodine content of 260 mg mL (BR2) and 320 mg mL" (BR21), respectively, and a size of 0.4 pm. BR2 contains 40 mg lipid mL and BR21 20 mg mL L In rabbits, BR2 tended to provide a higher and more persistent CT enhancement than BR21. 

Fig. 7.11. Kinetics of formation of Ins(l,4,5)P3 and diacylglycerol. The figure shows a model for the different dynamics of formation of Ins(l,4,5)P3 and of diacylglycerol (DAG), observed as a consequence of hormonal stimulation in an ideahzed ceU. An extracellular stimulus causes activation of the Ptdins specific phospholipase C (PL-CP or PL-Cy) on a sec timescale, and thus formation of Ins(l,4,5)P3 and DAG, and release of (not shown). The renewed increase in concentration of DAG is caused by the activation of phosphatidyl choline specific phospholipases of type C and phospholipase of type D. According to Liscovitch, (1992).

Incorporation of phosphatidyl choline and AMP signals into the large, broad envelope was unexpected because it had not been observed before with studies involving model compounds in a concentrated humic matrix with FeEDTA present (44). However, these model compound studies were conducted at a phosphorus concentration of 150 mg of P/L, a concentration 10 times greater than the amount that was spiked into sample I. This fact,... 

Figure 8.7. Fluorescence micrographs of a monolayer of L-a-dipalmitoyl phosphatidyl choline containing about 1% molar of an NBD dye at a temperature of 17°C and at pH 5.5. (Reproduced from Florsheimer, M. and Mdhwald, H. 1989 Chem. Phys. Lipids 49 231-41 by kind permission of the publishers and authors.)...

Dipalmitoyl phosphatidyl choline (L-a), alias DPL, and the sodium salt of dicetyl (hexadecyl or palmityl) phosphate were purchased from... 

As shown in Table 1, the acyl moiety of cardiolipin is comprised almost entirely of unsaturated fatty acids. Other membrane phospholipids such as phosphatidyl choline and phosphatidyl ethanolamine contain 10-40 mol of saturatedfatty acids such as palmitic acid (Cl6 0) and stearic acid (Cl8 0) per 100 mol of total fatty acids. In particular,linoleic acid (Ci8 2) is the most abundant polyunsaturated fatty acid consisting of 80 mol%, linolenic acid (Ci8 3) 8 mol%, and oleic acid (Cl8 l) 6 mol%. Therefore, by using a commercially available cardiolipin purified from bovine heart mitochondria, we characterized auto-oxidation products by reverse phase HPTLC and reverse phase HPLC. 

Ma, L., Ramachandran, C., and Weiner, N. D. (1991), Partitioning of a homologous series of alkyl p-amino benzoates in dipalmitoyl phosphatidyl choline liposomes Effect of liposomes type, Int. J. Pharm., 70, 209-218. 

The structures of the two monomeric surfactants used in this work, 1,4 sorbitan sesquioleate (Arlacel 83) and L,o-dipalmitoyl phosphatidyl choline, used in the impure form of soya bean lecithin, are very different from the block copolymer Bl both can be considered to be V-shaped and about 3 nm in overall length. A comparison of the film thicknesses obtained for the three surfactants is given in Table V. The film thickness for sorbitan sesquioleate is... 

Tyr-Met, Trp-Met and Met-Met) have been studied by pulse radiolysis and steady-state y-radiolysis in aqueous and lipid vesicle suspensions. In Met-enkephalin, the attack of the H atoms occurs to -50% on Met with formation of methanethiyl radicals (CH3S ) (Scheme 10 peptide = Tyr-Gly-Gly-Phe-). The remaining percentage is divided roughly evenly between Tyr and Phe. The formation of diffusible CH3S derived from the reaction presented in Scheme 10 was monitored using tmns lipids as a biomarker in the peptide-liposome (l-palmitoyl-2-oleoyl phosphatidyl-choline (POPC) vesicles) system. The cis-tmns isomerization of phospholipids was detected due to the catalytic action of thiyl radicals vide supra. Scheme 1). 

A popular probe molecule which has b n employed for such studies is 1,6 diphenyl 1,3,5 hexatriene (DPH). This molecule has both absorption and emission along the long molecular axis and is thought to dissolve in the hydrocarbon interior. Time-resolved fluorescence depolarization studies with DPH probe molecules have been performed on the following bflayer syrtems dKdihydrosteraculoyl)pho halidyl choline dipalmitoyl phosphatidyl choline L-a-dimyristollecithin residues egg lecithin residues and mouse leukaemic L 1210cells In all reports the time-dependence of the emission anisotropy was found to decay non xponentially indkat-ing either... 

Carrion, E.J. De La Maza, A. Parra, J.L. The influence of ionic strength and lipid bilayer charge on the stability of liposomes. J. Colloid Interface Sci. 1994, 164, 78-87. Duzgiines, N. Sur, S. Wilschut, J. Bentz, J. Newton, C. Portis, A. Papahadjopoulos, D. Calcium- and magnesium-induced fusion of mixed phosphatidylserine/phosphatidyl-choline vesicles effect of ion binding. J. Membr. Biol. 1981, 59, 115-125. 

The phospholipid monolayers examined in this study were all saturated, symmetric, l,2-diacyl-j -glycero-3-phosphate-based lipids. Four different lipid headgroups attached to the phosphate were examined choline, ethanolamine, glycerol and serine. Each lipid features a glycerol backbone, two saturated fatty acid chains and a phosphatidyl headgroup. 

Inhibition of peroxidation of unsaturated lipid chains in biomembranes is of particular significance and interest, because uncontrolled oxidation disrupts the protective layer around cells provided by the membranes. Furthermore, radical chain transfer reactions can also initiate damage of associated proteins, enzymes and DNA. The volume of literature is immense and expanding in the field of antioxidants. We will select certain milestones of advances where micelles and lipid bilayers, as mimics of biomembranes, provided media for quantitative studies on the activities of phenolic antioxidants. One of us, L. R. C. Barclay, was fortunate to be able to spend a sabbatical in Dr. Keith Ingold s laboratory in 1979-1980 when we carried out the first controlled initiation of peroxidation in lipid bilayers of egg lecithin and its inhibition by the natural antioxidant a-Toc . A typical example of the early results is shown in Figure 4. The oxidizability of the bilayer membrane was determined in these studies, but we were not aware that phosphatidyl cholines aggregate into reverse micelles in non-protic solvents like chlorobenzene, so this determination was not correct in solution. This was later corrected by detailed kinetic and P NMR studies, which concluded that the oxidizability of a lipid chain in a bilayer is very similar to that in homogeneous solution . ... 

Glycerophospholipids (PL) are abundant lipid components found in Nature [1]. Most vegetable oils, fish oil and egg yolk are particularly rich in mixtures of phospholipids. They are characterized by the presence of a polar head and two fatty acid chains in the apolar part of the molecule. The two acyl chains mainly consist of saturated fatty acid residues in the snl position and mainly (poly)unsaturated fatty acid chains in the sn2 position. Mixtures of phospholipids at low cost are obtained from the degumming process of vegetable oils. Lecithin, the main component of the mixture, has the polar head characterized by the choline residue. It is usually defined as phosphatidyl choline (PC) and it is understood that the composition of the apolar part is composed of mixtures of fatty acid residues dependent to a large extent on the source of the raw material (fatty acid chains composition of PC from soy beans palmitic 11.6%, stearic 3.4%, oleic 4.6%, linoleic 66.4%, linolenic 8.7%). Scheme 1 shows a PC with two defined acyl chains at the glycerol backbone l-palmitoyl-2-linoleoyl-5n-glycero-3-phosphocholine (PLPC). 

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