Ethers cholesteryl

It is, of course, also possible that the esterified cholesterol formed in HDL may be removed from plasma by some process other than uptake of the whole HDL particle or LTP-I-mediated transfer to other lipoprotein particles, but this possibility has not been fully investigated. Some evidence that there may be other pathways than these for the removal from plasma of HDL esterified cholesterol comes from the studies of Class et al. (G5, G6), who showed that cholesteryl ether incorporated in rat HDL as a tracer for cholesteryl ester was taken up in vivo by the rat liver (and by other organs) fester than apoA-I tracer (see Section 4.1.2). These studies are complicated by the relatively high concentration of apoE in rat HDL (compared, for instance, to man) and the unknown effect of apoE on HDL cholesteryl ester metabolism in the rat. Further studies on the removal of esterified cholester-... 

Synthesis of iodine-125 labelled co-lodoundecenyl cholesteryl ether (307)... 

Of the activated alcohols described in Section 1.1.2.S.1, alkyl sulfonates ate convenient alkylating re-agents because they can be readily prepared and handled. The correct choice of sulfate-alcoholate combination is often crucial for successful ether synthesis. Thus, for the preparation of cholesteryl ethers from the tosyl derivative of cholesterol and alkoxides, the reaction must be carried out at 110 °C for 2.S h in a sealed tube. Alternatively, the sodium salt of cholesterol can be reacted with an alkyl mesylate at 80 °C for 1 h in DMF to give the corresponding ether in 62-68% yield. ... 

Several different approaches have been used to investigate the cellular metabolism of CE. It is possible, for example, to extract CE from plasma lipoproteins and then replace it with radioactive CE, fluorescent CE, or radioactive cholesteryl ethers... 

The lyotropic liquid crystals have been studied as a separate category of liquid crystals since they are mostly composed of amphiphilic molecules and water. The lyotropic liquid-crystal structures exhibit the characteristic phase sequence from normal micellar cubic (IJ to normal hexagonal (Hi), normal bicontinuous cubic (Vi), lamellar (1 ), reverse bicontinuous cubic (V2), reverse hexagonal (H2), and reverse micellar cubic (I2). These phase transitions can occur, for instance, when increasing the apolar volume fraction [9], or decreasing the polar volume fraction of the amphiphilic molecule, for example, poly(oxyethylene) chain length in nonionic poly(oxyethylene) alkyl (oleyl) or cholesteryl ether-based systems (10, 11). 

Furthermore, Kunieda and coworkers were interested in replacing the traditional surfactants with environmentally friendly molecules to overcome biodegradation processes and aquatic toxicity [25]. The main environmentally friendly surfactants that were explored were poly(oxyethylene) cholesteryl ethers (ChEOn, where n is the number of oxyethylene, EO, units) with a bulky hydrophobic cholesteric group of natural origin [25-27]. Due to the distinct segregation tendency between the hydrophilic and hydrophobic groups, compared to the conventional alkyl ethoxylated surfactants, their phase behavior as a function of ethylene oxide... 

Phase Transitions Within Poly(oxyethylene) Cholesteryl Ethers-Based Systems... 

A.2 Phase Transitions Within Pol f (oxfethfkne) Cholesteryl Ethers-Based Systems 93... 

In order to improve the understanding of these systems, Kunieda and coworkers examined the thermotropic behavior of poly(oxyethylene) cholesteryl ethers with different chain lengths, ChFOn, mixed with water at a fixed concentration ( 25 wt%) [32]. This study focused on the different fusion mechanisms that were involved in the solid-liquid phase transition. The soUd-Uquid transition temperature for ChFOn as a function of n is shown in Figure 4.3 (for comparison, the transition temperature for polyethylene glycol is also shown). In both cases, the transition temperature decreased when the chain length was diminished. However, for the cholesterol surfactant, when n < 10, a birefringent phase appeared between... 

It was shown that replacing the traditional surfactants by environmentally friendly molecules, such as poly(oxyethylene) cholesteryl ethers, to overcome the biodegradation process and aquatic toxicity resulted in the formation of diverse unique liquid-crystalline phases. The abihty to obtain novel intermediate phases was attributed to the bulky and nonflexible hydrophobic part of the surfactants and intricate hydrophobic-hydrophihc balance controlled by the different EO chain length. 

Kunieda s group reported numerous viscoelastic worm-like micellar systems in the salt-free condition when a lipophilic nonionic surfactant such as short hydrophilic chain poly(oxyethylene) alkyl ether, C EOni, or N-hydroxyethyl-N-methylaUcanolamide, NMEA-n, was added to the dilute micellar solution of hydrophilic cationic (dodecyltrimethylammonium bromide, DTAB and hexade-cyltrimethylammonium bromide, CTAB) [12-14], anionic (sodium dodecyl sulfate, SDS [15, 16], sodium dodecyl trioxyethylene sulfate, SDES [17], and Gemini-type [18]) or nonionic (sucrose alkanoates, C SE [9, 19], polyoxyethylene cholesteryl ethers, ChEO [10, 20], polyoxyethylene phytosterol, PhyEO [11, 21] and polyoxyethylene sorbitan monooleate, Tween-80 [22]) surfactants. The mechanism of formation of these worm-Hke stmctures and the resulting rheological behavior of micellar solutions is discussed in this section based in some actual published and unpublished results, but conclusions can qualitatively be extended to aU the systems studied by Kunieda s group. 

Maestro et al. (2004) [9] studied the R effect on the formation and disruption of the transient network formed by worm-hke micelles, using C12EO4 as the cosurfactant Oscillatory results at low and intermediate frequencies were fitted to the Maxwell model, as had been done in other pubUcations [9j. The obtained parameters Go and Tm are presented in Eigure 12.8 vs. ratio R. It can be observed that when R is increased. Go continuously grows, nearly reaching a plateau. On the other hand, Tm quickly increases up to the R for which the viscosity maximum is found, and then decreases up to phase separation. Kunieda s group found the same tendencies for other worm-hke micellar systems, like the water-polyoxyethylene cholesteryl ether Ch(EO) -Ci2(EO) systems [lOj. Eigure 12.9 shows some until... 

Figure 12 (a) Partial phase diagram of the water/polyoxyethylene cholesteryl ether(ChEOio)-Ci2E03 system, in the dilute region at 25 °C, (b) Variation of zero-shear... 

Sakai, T., and Kunieda, H. (2004) Phase behavior of poly (oxyethylene) cholesteryl ether/novel alkanolamide/ water systems. J. Colloid Interface Sci., 277, 235-242. 

Phase behavior and self-organized structures in water/ poly(oxyethylene) cholesteryl ether systems./. Phys. Chem. 5,108,12927-12939. 

Synonyms PEG-10 cholesteryl ether PEG 500 cholesteryl ether POE (10) cholesteryl ether Definition PEG ether of cholesterol with avg. ethoxylation value of 10 Properties Nonionic Toxicology TSCA listed Uses Emulsifier, solubilizer, dispersant, thickener in cosmetics, hair care, creams/iotions... 

Synonyms PEG-20 cholesteryl ether PEG 1000 cholsteryl ether POE (20) cholesteryl ether... 

PEG-5 cholesteryl ether. See Choleth-5 PEG-10 cholesteryl ether. See Choleth-10 PEG-15 cholesteryl ether. See Choleth-15 PEG-20 cholesteryl ether. See Choleth-20 PEG-24 cholesteryl ether. See Choleth-24 PEG-30 cholesteryl ether. See Choleth-30 PEG 500 cholesteryl ether. See Choleth-10 PEG 1000 cholsteryl ether. See Choleth-20 PEG-3 C11 linear alcohol. See Undeceth-3 PEG cocamide CAS 61791-08-0 (generic)... 

POE (5) cholesteryl ether. See Choleth-5 POE (10) cholesteryl ether. See Choleth-10 POE (15) cholesteryl ether. See Choleth-15 POE (20) cholesteryl ether. See Choleth-20 POE (24) cholesteryl ether. See Choleth-24 POE (30) cholesteryl ether. See Choleth-30 POE (6) cocamide ether carboxylic acid, sodium salt. See Sodium PEG-6 cocamide carboxylate POE (8) cocamine. See PEG-8 cocamine POE (20) cocamine. See PEG-20 cocamine POE (15) cocamine oleate/phosphate. See PEG-15 cocamine oleate/phosphate POE (65) cocoa butter glycerides. See PEG-75 cocoa butter glycerides POE (2) coco-benzonium chloride. See PEG-2 coco-benzonium chloride POE (10) coco-benzonium chloride. See PEG-10 coco-benzonium chloride POE (2) cocomonium chloride. See PEG-2 cocomonium chloride... 

TABLE 4 Thermodynamic Parameters of Polyoxyethylene (30) Cholesterol CMC Values, Micellar Weight, and Aggregation Numbers of Polyoxyethylene Cholesteryl Ethers in Water... 

Kabalka, G. W., Varma, R. S., Jineraj, U. K., Huang, L., Painter, S. K. 1985. Synthesis of i-125 labeled otnega-iodoundecyl cholesteryl ether J. Label. Compd. Radiopharm. 22 333-338. 

Fig. 3 Effect of cholesteryl ethers in liposomes prepared with DOPC on the relative amount of glucose released (A) (x) cholesterol (o) cholesteryl methyl ether ( ) cholesteryl ethyl ether (v) cholesteryl-n-propyl ether ( ) cholesteryl isopropyl ether (A) cholesteryl butyl ether (B) (x) cholesterol (o) cholesteryl (2 -hydroxy)-3-ethyl ether ( ) cholesteryl methoxy methyl ether ( ) cholesteryl acetate.

The reaction of alkyl bromides with alcohols to form ethers, promoted by silver salts of dicarboxylic acids, the Koenigs-Knorr synthesis, is sometimes complicated by the recovery of the ether from the dicarboxylic acid. A copolymer network of maleic acid and l,4-bis(vinyloxy)butane was transformed into the silver salt (41) and used for the reaction of 2,3,4,6-tetra-O-acetyl-la-bromoglucopyranose with cholesterol to give the cholesteryl ether in 55% yield as shown in Scheme The polymeric by-product dicarboxylic acid was filtered easily from the product solution. 

Synonyms PEG-5 cholesteryl ether POE (5) cholesteryl ether Definition PEG ether of cholesterol with avg. ethoxylatlon value of 5... 

Synonyms PEG-10 cholesteryl ether PEG 500 cholesteryl ether POE (10) cholesteryl ether... 

PEG-25 cetyl/stearyl ether carboxylic acid. See Ceteareth-25 carboxylic acid PEG-8 C12-14 fatty alcohol. See C12-14 pareth-8 PEG-9 C12-14 fatty alcohol. See C12-14 pareth-9 PEG-7 C16-18 fatty alcohol. See C16-18 pareth-7 PEG-3 C12-13 fatty alcohol ether. See C12-13 pareth-3 PEG-7 C12-13 fatty alcohol ether, See C12-13 pareth-7 PEG-3 C12-15 fatty alcohol ether. See C12-15 pareth-3 PEG-7 C12-15 fatty alcohol ether. See C12-15 pareth-7 PEG-5 cholesteryl ether. See Choleth-5 PEG-10 cholesteryl ether. See Choleth-10 PEG-15 cholesteryl ether. See Choleth-15 PEG-20 cholesteryl ether. See Choleth-20 PEG-24 cholesteryl ether. See Choleth-24 PEG-30 cholesteryl ether. See Choleth-30 PEG 500 cholesteryl ether. See Choleth-10 PEG 1000 cholsteryl ether. See Choleth-20 PEG-3 C11 linear alcohol. See Undeceth-3 PEG cocamide CAS 61791-08-0 (generic)... 

POE (5) cholesteryl ether. See Choleth-5 POE (10) cholesteryl ether. See Choleth-10 POE (15) cholesteryl ether. See Choleth-15 POE (20) cholesteryl ether. See Choleth-20 POE (24) cholesteryl ether. See Choleth-24 POE (30) cholesteryl ether. See Choleth-30... 

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