Dicetyl phosphate

Fig. 6 Structure of membrane components (a) dioctadecyldimethylammonium bromide, (b) 1,2-dimyristoyl, s7i-glycero-3-phosphocholine (DMPC), (c) 1,2-dilauroyl, S7i-glycero-3-phospho-choline (DLPC), (d) dicetyl phosphate (DCP)...

Figure 6. Average area per molecule of dicetyl phosphate-cholesterol monolayers at various surface pressures...

The concept of ion-dipole interaction between lecithin and cholesterol has been suggested by many workers for the packing of these lipids in myelin or in the cell membrane (18, 19, 52). This concept is not supported by the surface potential measurements of mixed monolayers of lecithin and cholesterol. In contrast to dicetyl phosphate-cholesterol... 

Monolayers of dicetyl phosphate-cholesterol follow the additivity rule for average area per molecule, whereas lecithin—cholesterol mono-layers deviate from it. The reverse is true for the additivity rule of average potential per molecule. Thus, the surface potential indicates that there is no interaction (or complex formation) between lecithin and cholesterol, but there is ion-dipole interaction between dicetyl phosphate and cholesterol as well as between phosphatidic acid and cholesterol. 

Tn previous reports (1,2,3) we described the surface potential (AV) response of films of isoelectric phospholipids in the presence of anionic and cationic contaminants, either when the lipids were spread on electrolyte solution or when the latter was injected under the lipid film that had been spread on water. In the presence of 10 wt % acidic contaminant (dipalmityl phosphate, dicetyl phosphate, and dicapryl phthalate (DCP)... 

Multilamellar liposomes composed of dipalmitoylphosphatidylcholine (DPPC) and dicetyl phosphate (DCP) were prepared by the formation of a thin lipid film and subsequent sonication, and coated with chitosan (Ch) [36], Liposomes with a size of approximately 5 pm were used in the experiment. The Ch-coated and plain liposomes were compared in terms of mucoadhesion to the rat stomach and intestinal parts. Although both the liposomes were less adhesive to the stomach, Ch-coated liposomes displayed much higher mucoadhesion to all the intestinal parts in vitro than the plain liposomes. The intestinal adhesion of the plain liposomes were minimal. Further, Ch-coated liposomes showed a great mucoadhesion to the intestine at acidic and neutral pH values. This was also confirmed by fluorescence microscopy when pyrene-loaded Ch-coated liposomes were used in the mucoadhesion test. 

Occlusion is a condition that could affect drug transport from niosomes and through the stratum corneum. Such an effect was reported for saturated estradiol niosomal formulations composed of polyoxyethylene alkyl ether surfactants and sucrose ester surfactants with cholesterol and dicetyl phosphate, for which occlusion enhanced the drug human stratum corneum transport [43]. 

Talsma [1.34] showed with phospholipon 100 H, a hydrated phosphatidylcholine of soya beans (Nattermann, Cologne), and dicetyl phosphate (DCP) (molar ratio 10 1) from which bilayer liposomes have been produced, the influence of one CPA (I), of several CPAs (II), of the vesicle size (III) and the cooling rate (IV). In all of the following tests Tris buffer of pH 7.4 was used. 

Niosomes are non-ionic surfactant vesicles. They have been used to develop a vaccine-delivery system by peroral and oral routes. Ovalbumin was encapsulated in various lyophilized niosome preparations consisting of sucrose esters, cholesterol, and dicetyl phosphate. Encapsulation of ovalbumin into niosomes consisting of 70% stearate sucrose ester and 30% pal-mitate sucrose ester (40%i mono-, 60% di/triester) resulted in a significant increase in antibody titers in serum, saliva, and intestinal washings. ... 

Abrahamson et at (34) observed a similar departure from the latter sequence of calcium and magnesium in their reaction with a phosphatidic acid dispersion at pH 7. Shah and Schulman (35) also found a higher tendency of Ca2+ than Mg2+ to interact with a monolayer of dicetyl phosphate at pH 5.6 as judged by surface pressure measurements although surface potential measurements indicated little difference between the two ions as did potential measurements on phosphatidyl serine mem-... 

Figure 6. Variation of A7r and r for 1-14C-acetyl-lysozyme (Cp = 5.6 X 10 5 %) adsorbing to various lipid monolayers at = 10 dynes/cm. Substrate was phosphate buffer (pH 7, I = 0.1), and the monolayers were egg lecithin (PC), egg phosphatidyleihanolamine (PE), ox brain phosphatidylserine (PS), dicetyl phosphate (DCP)y and arachidic acid.

An indication of the role of electrostatic effects follows. The net charge on a -casein molecule at pH 7 is (— )13 (11), but Att and r are only slightly affected when, under given conditions, egg lecithin is replaced by lipids (e.g. phosphatidylserine, dicetyl phosphate, and arachidic acid) with a net negative charge. Electrostatic effects play a minor role in the interaction of /3-casein with insoluble lipid monolayers. A comparative series of experiments with lysozyme show some major effects. The results are summarized in Figure 6 where Att and r for lysozyme adsorbing to a variety of lipid monolayers at Cp1 = 5.6 X 10"5 % and... 

Bromination of acetal (98) and dehydrobromination gave unsaturated acetal (99) <83AQ2io>. Hemiacetals, (e.g., (100)), have been synthesized for use as covalent carriers and for the preparation of liposomes containing dicetyl phosphate, cholesterol, and trypsin <87GEP(0)3619883>. Bis-hemiacetal (101) could be obtained by the reaction of hexafluoroacetylacetone and glycol, but this compound decomposes on standing <67NKZ470>. 

Fluorometric and spectrophotometric studies of filipin-cholesterol interaction showed that the stoichiometry of the interaction was 1 1 [150] or 1 1.5 [146,147]. UV spectrophotometry changes have been used to monitor the stoichiometry of the interaction between filipin and free or liposome-bound cholesterol. Analysis of aqueous dispersions suggested that the stoichiometry was 1 1 [171]. Lecithin, dicetyl phosphate-cholesterol liposomes only produced maximal spectral changes of filipin when the sterol polyene ratio was 1 1 [172]. Filipin released trapped ion markers from sterol—phospholipid liposomes. The rate of release was dependent upon cholesterol content of the liposome membrane (maximum at sterol phospholipid ratio of 1 1) and upon the molar fllipin sterol ratio (maximum at fllipin sterol ratio of 1 1). 

Di-n-hexadecyl adipate. See Dicetyl adipate Dihexadecylamine. See Dipalmitamine Dihexadecyidimethylammonium chloride. See Dicetyidimonium chloride Dihexadecyl hexanedioate. See Dicetyl adipate Dihexadecyl hydrogen phosphate Dihexadecyl phosphate. See Dicetyl phosphate Dihexadecyl, 3,3 -thiobispropionate. See Dicetyl thiodipropionate Dihexyl. See n-Dodecane Dihexyl adipate... 

Phosphoric acid, dihexadecyl ester. See Dicetyl phosphate... 

Acacia famesiana Acacia Senegal Diacetyl tartaric acid esters of mono- and diglycerides Gum ghatti Polyglyceryl-3 shortening Potassium citrate Sodium thiosulfate pentahydrate Sucrose fatty acid esters emulsifier, biomedical research Dicetyl phosphate emulsifier, biotechnology Lauroyl sarcosine emulsifier, bitumen... 

Panthenyl hydroxypropyl steardimonium chloride C32H67O4P Dicetyl phosphate C32H68NO9 Cl... 

Negatively charged (ingredients egg lecithin-cholesterol—phosphatidic acid-dicetyl phosphate, ratio 33 4.46 10 3.24 mg)... 

Chem. Descrip. Cetearyl alcohol, dicetyl phosphate, and celeth-10 phosphate Ionic Nature Mild anionic... 

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