Sodium taurocholate surfactant

Conjunctival insulin absorption in rabbits estimated as plasma insulin levels after punctal occlusion was also shown to be increased by bile salts (sodium deoxycholate, glycocholate, and taurocholate) and a surfactant (polyoxyethylene-9-lauryl ether) [200], Their rank order of effectiveness at 1% was sodium deoxycholate > polyoxyethylene-9-lauryl ether > sodium glycocholate = sodium taurocholate. There was an 18-, 29-, 3-, and 3-fold increase, respectively, in conjunctival absorption. Sodium deoxycholate, a dihydroxy bile salt, was more effec-... 

Several ehemical enhancers, such as sodium ethylenediaminetetraacetate and sodium taurocholate, oleic acid [37], polyoxyethylated nonionic surfactants, citric acid, and dihydroxy bile salts open the paracellular route, presumably by disruption of the intraeellular OJC funetion [37], The use of nitrie oxide is another approach [39], Moreover, manipulation of the cyclooxygenase pathway activities to trigger the release of eompounds like substance P may provide another means for altering colonic permeability [40],... 

Surfactants disrupt the cell wall by solubilizing the lipids in the wall. Sodium dodecylsulfate (SDS), sodium sulfonate, Triton X-100, and sodium taurocholate are examples of the surfactants often employed in the laboratory. Alkali treatment disrupts the cell walls in a number of ways including the saponification of lipids. Alkali treatment is inexpensive and effective, but it is so harsh that it may denature the protein products. Organic solvents such as toluene can also rupture the cell wall by penetrating the cell wall lipids, swelling the wall. When red blood cells or a number of other animal cells are dumped into pure water, the cells can swell and burst due to the osmotic flow of water into the cells. 

Sodium-/V-dodecanoyl-L-valinate (SD Val) Biological surfactants Bile salt surfactants Sodium cholate Sodium taurocholate... 

Natural surfactants such as sodium taurocholate and sodium glycocholate are not able to eliminate the limiting character of the aqueous diffusion layer adjacent to the luminal side of the membrane [29, 30]. For that reason in the presence of these natural surfactants at their CMC, the absorption Hpophihdty correlations are as hyperbolic as the ones obtained without additives. Figure 4.3 displays the difference between the correlations obtained in the presence of polysorbate 80 and sodium taurocholate [27, 28]. 

An example of the correlations obtained in small intestine in the absence and in the presence of tetradecyltrimethylamonium bromide (TTAB) at 0.0125% (CMC) is represented in Fig. 4.4 [26]. As can be seen, the effect of each surfactant concentration is quite significant. But, a natural surfactant such as sodium taurocholate did not produce any significant change in the absorption rate constants of a series of phenyl-alkyl carboxylic acids at its CMC and it exerted an almost negligible solubilization effect at a supramicellar concentration [23]. 

The possible reasons for the different behavior of natural surfactants could include the following. Natural surfactants lead to surface tension values higher than those corresponding to the same concentration of a synthetic surfactant. The ability to nullify the aqueous layer resistance could be related with the surface tension values. However, the micelles of bile salts are smaller and more rigid than the micelles of synthetic surfactants. The solubilization potential of bile salts is increased in the presence of lecithins and fatty acids. For instance, the absorption rate constants obtained in the presence of sodium taurocholate and glycocholate mixed-micelles with lecithin for a series of acids were significantly lower than those obtained in the presence of simple micelles of the same bile salts [29, 30]. 

Chiral surfactants The chiral separation of anal5des is based on their partition coefficients between the chiral micelle phase and the electrolyte bulk phase. Alkylglucosides, alkylmaltoside, sodium cholate, saponines, sodium dodecyl sulfate, sodium taurocholate. Ephedrine, fenoldopam, hexobarbital, ketamine, pindolol, timolol, etc. 

Figure 3 The effect of temperature on the three-phase region at constant salinity in a surfactant (sodium taurocholate NaTQ/ brine/cosurfactant (monoglycerideTEH)/oil (triglyceride THE) system. The three-phase...

Bile salts are natural and chiral anionic surfactants which form helical micelles of reversed micelle conformation. The first report on enantiomer separation by MEKC using bile salts was the enantioseparation of dansylated DL-amino acids (Dns-o,L-AAs) and, since then, numerous papers have been available. Nonconjugated bile salts, such as sodium cholate (SC) and sodium deoxycholate (SDC), can be used at pH > 5, whereas taurine-conjugated forms, such as sodium taurocholate (STC) and sodium taurodeox-ycholate (STDC), can be used under more acidic conditions (i.e., pH > 3). Several enantiomers, such as diltiazem hydrochloride and related compounds, carboline derivatives, trimetoquinol and related compounds, binaphthyl derivatives, Dhs-dl-AAs, mephenytoin and its metabolites, and 3-hydroxy-l,4-benzodiazepins have been successfully separated by MEKC with bile salts. In general, STDC is considered as the the most effective chiral selector among the bile salts used in MEKC. 

Agents capable of promoting absorption and/or permeation were discussed in a recent review . The intestinal absorption of sulfamethoxypyridazine, diphenhydramine, salicylic acid, p-hydroxybenzoic acid and heparin was facilitated in the presence of surfactants, as was the intramuscular absorption of enduracidin . The effect of sodium taurodeoxycholate on drug transport across biological barriers was studied " . Mixed micellar solutions of a fatty acid, a monoglyceride and sodium taurocholate had a greater effect on the absorption of... 

Ekwall and Baltcheffsky [265] have discussed the formation of cholesterol mesomorphous phases in the presence of protein-surfactant complexes. In some cases when cholesterol is added to these solutions a mesomorphous phase forms, e.g. in serum albumin-sodium dodecyl sulphate systems, but this does not occur in serum albumin-sodium taurocholate solutions [266]. Cholesterol solubility in bile salt solutions is increased by the addition of lecithin [236]. The bile salt micelle is said to be swollen by the lecithin until the micellar structure breaks down and lamellar aggregates form in solution the solution is anisotropic. Bile salt-cholesterol-lecithin systems have been studied in detail by Small and coworkers [267-269]. The system sodium cholate-lecithin-water studied by these workers gives three paracrystalline phases I, II, and III shown in Fig. 4.37. Phase I is equivalent to a neat-soap phase, phase II is isotropic and is probably made up of dodecahedrally shaped lecithin micelles and bile salts. Phase III is of middle soap form. The isotropic micellar solution is represented by phase IV. The addition of cholesterol in increasing quantities reduces the extent of the isotropic... 

Recently, insulin absorption via the jejunum has been effected by administration of insulin-cetomacrogol solutions to diabetic rats [87]. Results presented in Table 7.5 are most likely to be due to a membrane effect rather than a surfactant-protecting effect on insulin degradation, as insulin administered h after cetomacrogol elicited a hypoglycaemic effect (see Section 7.4.2 below on rectal absorption). Sodium lauryl sulphate (0.75%) and sodium taurocholate (3.2 %) have been reported to cause an increase in the percentage of insulin absorbed from the ligated rat jejunal loop from 0.4% to 3.2% and 3.4%,... 

Figure 7.29 Plasma clearing factor activity after the administration into the large intestine. Several types of mixed micelles containing oleic acid were tested. Each value is the mean sem of 4 to 5 animals. NaTC = sodium taurocholate HCO-60 = hydrogenated castor oil based non-ionic surfactant with 60 ethylene oxide units. From Taniguchi et al [117] with permission.

The purification of kid pregastric lipase was described earlier [20]. The surfactants cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), bis(2-ethylhexyl) sodium sulfosuccinate (Aerosol-OT) (AOT), soybean lecithin, Tween 20, sodium taurocholate (NaTC), and Triton X-100 (TX-lOO) were purchased from Sigma. Stock solutions of surfactants were prepared in 50 mM Bis-Tris buffer, pH 6.5, 25°C. The substrates 4-nitro-phenyl butyrate (4-NPB) and tributyrin were also purchased from Sigma. 

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