Bile salts chemical structure

KP and v can, in contrast to kp, not be determined via the concentration gradient for binary and ternary mixed micelles, because for the calculation of the Nemstian distribution a constant CMC and an almost constant partial molar volume must be assumed. The calculation of aggregation constants of simple bile salt systems based on Eq. (4) yields similar results (Fig. 8b). Assuming the formation of several concurrent complexes, a brutto stability constant can be calculated. For each application of any tenside, suitable markers have to be found. The completeness of dissolution in the micellar phase is, among other parameters, dependent on the pH value and the ionic strength of the counterions. Therefore, the displacement method should be used, which is not dependent on the chemical solubilization properties of markers. For electrophoretic MACE studies, it is advantageous for the micellar constitution (structure of micelle, type of phase micellar or lamellar) to be known for the relevant range of concentrations (surfactant, lipids). 

The fat-soluble vitamins share many properties despite their limited chemical similarity. They are absorbed into the intestinal lymphatics, along with other dietary lipids, after emulsification by bile salts. Lipid malabsorption accompanied by steatorrhea usually results in poor uptake of all the fat-soluble vitamins. Deficiency disease (except in the case of vitamin K) is difficult to produce in adults because large amounts of most fat-soluble vitamins are stored in the liver and in adipose tissue. The fat-soluble vitamins are assembled from isoprenoid units this fact is apparent from examination of the structures of vitamins A, E, and K cholesterol, the precursor of vitamin D, is derived from six isoprenoid units (Chapter 18). Specific biochemical functions for vitamins A, D, and K are known, but a role for vitamin E, other than as a relatively nonspecific antioxidant, remains elusive. 

The natural distribution and the chemical structure of bile alcohols and primitive bile acids indicate that these compounds found in lower vertebrates are evolutionary precursors of the common bile acids found in mammalian species. Haslewood proposed that the mechanism of conversion of cholesterol to the common bile acids in mammals is a recapitulation of the evolution of bile salts and thus would entail the intermediary formation of bile alcohols and primitive bile adds similar to or the same as those found in lower species [120]. Thus, studies have been carried out to test whether the naturally occurring bile alcohols and primitive bile acids are intermediates in the biosynthetic pathway between cholesterol and the C24 bile acids in mammals. There is no doubt that such studies contributed to the elucidation of the sequence of reactions in the biosynthesis of the mammalian C24 bile acids. 

Most of the lipids found in the body fall into the categories of fatty acids and triacylglycerols glycerophospholipids and sphin-golipids eicosanoids cholesterol, bile salts, and steroid hormones and fat-soluble vitamins. These lipids have very diverse chemical structures and functions. However, they are related by a common property their relative insolublity in water. 

What are the structural and chemical reasons why bile salts don t form typical micelles ... 

UlzmTun, E., Stephens, C., Crespo, E., Ruiz-CabeUo, F., Ruiz-Nunez, J., Saenz-L6pez, R, Moreno-Herrera, I., Robles-Diaz, M., Hallal, H., Moreno-Planas, J.M., Maria, R., Cabello, M.R., Lucena, M.I., and Andrade, R.J. (2013) Role of chemical structures and the 1331T>C bile salt export pump polymorphism in idiosyncratic drug-induced liver injury. Liver Int., 33, 1378-1385. 

Noninvasive delivery of insulin via most mucosal membranes requires the use of chemical enhancement for notable insulin absorption (see Section 3.3 and Table II). However, most permeation enhancers have, in addition to their effect on the mucosal membrane, an often pronounced influence on insulin three-dimensional structures. Thus, sodium salicylate (Touitou et al, 1987) as well as bile salts (Gordon etal, 1985) have been shown to dissociate insulin oligomers into monomers. This effect improves membrane permeability, but it may also reduce the physical stability and increase the susceptibility of insulin to enzymatic degradation. The exposure of new epitopes may also influence the immunological properties of the insulin formulation. 

Figure 5 (a and b) Chemical structure of the sodium salt of several bile acids 1 cholic acid, 2 chenodeoxycholate, 3 deoxychoUc acid, 4 glycocholic acid, 5 taurochoUc acid, and 6 tauro deoxychoUc acid, (c) Structures of micelles from choUc acid derivatives, proposed by Small and coworkers. Two or four molecules assemble because of hydrophobic interactions between the cholesterol groups. The hydroxyl groups (black dots on cholesterol) and the carboxylic acids side group shield the hydrophobic domain from water. (Refs. 22-24 for cmcs and Ref. 16 for aggregation numbers.) (Reproduced with permission from Ref. 21. Indian Academy of Sciences, 2004.)... 

Mrozek et al. synthesized fourteen acyloxy derivatives of 5(S-cholic acid as novel potential transdermal penetration enhancers and intestinal drug absorption modifiers (Figure 49.6). Nontoxic bile acid/salt derivatives (as amphiphilic compounds) are used widely in drug formulations as excipients and can influence gastrointestinal solubility, absorption, and chemical/enzymatic stability of drugs. Transdermal penetration enhancers are special pharmaceutical excipients that interact with skin components to increase the penetration of drugs into blood circulation after topical application. Structure confirmation of all generated compounds was accomplished by H NMR, NMR, IR, and mass spectrometer (MS) spectroscopy. 

---