Zwitterionic lipids

Phospholipids. For the removal of ionic contaminants from raw zwitterionic phospholipids, most lipids were purified twice by mixed-bed ionic exchange (Amberlite AB-2) of methanolic solutions. (About Ig of lipid in lOmL of MeOH). With both runs the first ImL of the eluate was discarded. The main fraction of the solution was evaporated at 40°C under dry N2 and recryst three times from n-pentane. The resulting white powder was dried for about 4h at 50° under reduced pressure and stored at 3°. Some samples were purified by mixed-bed ion exchange of aqueous suspensions of the crystal/liquid crystal phase. [Kaatze et al. J Phys Chem 89 2565 7955.]... 

The development of monoalkyl phosphate as a low skin irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste and liquid-type skin cleansers, and also phosphorylation reactions from the viewpoint of industrial production [26]. Amine salts of acrylate ester polymers, which are physiologically acceptable and useful as surfactants, are prepared by transesterification of alkyl acrylate polymers with 4-morpholinethanol or the alkanolamines and fatty alcohols or alkoxylated alkylphenols, and neutralizing with carboxylic or phosphoric acid. The polymer salt was used as an emulsifying agent for oils and waxes [70]. Preparation of pharmaceutical liposomes with surfactants derived from phosphoric acid is described in [279]. Lipid bilayer vesicles comprise an anionic or zwitterionic surfactant which when dispersed in H20 at a temperature above the phase transition temperature is in a micellar phase and a second lipid which is a single-chain fatty acid, fatty acid ester, or fatty alcohol which is in an emulsion phase, and cholesterol or a derivative. 

A glyceryl 2-aminoethylphosphonolipid has been isolated from Tetrahymenapyriformis and (45) has been detected by g.l.c.-mass spectrometry in both the lipid and proteinaceous fractions of human brain. The zwitterionic (45) was converted into volatile (46) by acetylation and methylation. Phosphonolipids derived from A-methyl-(45) have been synthesised by acetylation of A-methyl-(45) and subsequent conversion to the phosphorochloridate for the phosphorylation step. °... 

FIG. 9 A scheme representing lateral phase separation for anionic lipids from zwitterionic lipids in a mixed lipid bilayer induced by the peptide antibiotic, polymyxin-B. (Reprinted by permission from Ref. 41, copyright 1998, Elsevier Science.)... 

The GIT has about 13% wt/wt negatively charged lipid-to-zwitterionic phospholipid ratio. It is about twice as large in the BBB. Factoring this into the in vitro model is expected to be important. 

Wuhrer, M., Rickhoff, S., Dennis, R.D., Lochnit, G., Soboslay, P.T., Baumeister, S. and Geyer, R. (2000) Phosphocholine-containing, zwitterionic glycosphingo-lipids of adult Onchocerca volvulus as highly conserved antigenic structures of parasitic nematodes. BiochemicalJournal 348, 417-423. 

Figure 1 (Plate 1). A molecular view of a small section of a flat lipid bilayer generated by molecular dynamics simulations. The bilayers are composed of l-stearoyl-2-docosa-hexaenoyl-5M-g]ycero-3-phosphatidylcholine lipids, i.e. the sn 1 chain is 18 C atoms long and the sn2 chain has 22 carbons, including six cis double bonds. The hydrophobic core is in the centre of the picture, and the hydrated head-group regions are both on top and bottom of the view graph. The head group is zwitterionic and no salt has been added. From [102], Reproduced by permission of the American Physical Society. Copyright (2003)...

Figure 7. Lipophilicity profile of propranolol in liposomes composed of zwitterionic and charged lipids (phosphatidyl ethanolamine (PE), oleic acid (OA), phosphatidyl inositol (PI)). Conditions of measurements are described in [113]. The dotted line indicates the partitioning profile of propranolol in the egg PC liposome system. The bars show the pH-dependent charge profile of propranolol (hatched bars positively charged propranolol) and the lipids in the membrane (black bars negatively charged lipids). Reprinted from [113] Kramer, S. (2001). Liposome/water partitioning , In Pharmacokinetic Optimization in Drug Research, eds. Testa, B. et al. Reproduced by permission of Verlag Helvetica Chimica Acta, Zurich...

Aggregation of pseudoisocyanine (dye I, Fig. 3) and 5,5 -dichloro-3,3 -diethyl-9-phenylthiacarbocyanine chloride (dye II, Fig. 5) induced by the vesicles consisting of zwitterionic DMPC and anionic DCP (Fig. 6) lipids was studied in [28]. Both dyes were shown to form fluorescent J-aggregates upon addition of the vesicles formed of the mixture of DMPC and DCP with relative content equal to 1 1. At the same time, for both dyes pure DMPC vesicles did not induce the J-aggregation. Upon addition of the vesicles containing DMPC and DCP in the 4 1 ratio, as well as... 

Domain formation in binary mixtures of a polymerizable lipid and non-polymerizable lipid is well established for diacetylenic lipids. The rigid diacetylenic unit facilitates the formation of enriched domains in the condensed phase of monolayers or the solid-analogous phase of bilayers. Since diacetylenes polymerize most readily in solid-like states, most studies have focused on conditions that favor domain formation. Only in the case of a mixture of a charged diacetylenic lipid and a zwitterionic PC was phase separation not observed. Ringsdorf and coworkers first reported the polymerization of a phase-separated two-dimensional assembly in 1981 [33], Monolayer films were prepared from mixtures consisting of a diacetylenicPC (6) (Fig. 5) and a nonpolymerizable distearoyl PE (DSPE). 

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