Bile acids, salts

CHOLESTEROL IS EXCRETED FROM THE BODY IN THE BILE AS CHOLESTEROL OR BILE ACIDS (SALTS)... 

MEKC with chirally selective micelles has proved very powerful for enantiomer separation. Chiral surfactants (e.g., bile acid salts) forming chirally active micelles have widely been used. Mixed micellar solutions containing SDS and chiral surfactants or derivatized CDs are becoming more popular. Mixedmode, chiral, and nonchiral, interactions increase the resolving power of these systems. 

Bile is a complex fluid containing 95% water, electrolytes and organic molecules, including bile acids/salts, cholesterol, phospholipids and conjugated bilirubin that flows through the biliary tract into the small intestine (Table 2.6). 

In rodents, dogs, and monkeys, the permeability of the GI tract to antisense inhibitors has been significantly enhanced by using formulations containing penetration enhancers such as bile acid salts and fatty acids. After... 

The fifth main type occurs in systems in which the soap component is not an association colloid of the paraffin chain type but a salt of a bile acid, with its condensed four-ring skeleton with two or three hydroxyl groups and with one carboxyl group at the end of a branched hydrocarbon chain. Figure 29 shows the phase diagram for the sodium cholate-decanol-water system (9). There is no mesomorphous phase but one extensive continuous area with homogeneous isotropic solutions. The cholate and decanol are mutually soluble in the presence of water, as in the case of the soap and the alcohol in the soap-alcohol systems, but here we have the remarkable phenomenon that water and decanol, which are practically insoluble in one another, become mutually soluble in all proportions in the presence of a certain quantity of a bile acid salt. 

Fig. 13.16. Representation of the structure of bile acid salt micelles.

Reis, S., Moutinho, C., Matos, C., Castro, B., Gameiro, P., and Lima, J. 2004, Noninvasive methods to determine the critical micelle concentration of some bile acid salts. Anal. Biochem. 334,117. 

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. 

Mammalian bile contains sodium salts of conjugated bile acids, e.g. glycocholic acid and taurocholic acid, in which cholic acid is combined (amide linkage) with glycine and taurine respectively. 

A significant fraction of the body s cholesterol is used to form bile acids Oxidation m the liver removes a portion of the CsHi7 side chain and additional hydroxyl groups are intro duced at various positions on the steroid nucleus Cholic acid is the most abundant of the bile acids In the form of certain amide derivatives called bile salts, of which sodium tau rocholate is one example bile acids act as emulsifying agents to aid the digestion of fats... 

Biguanide salts Biimidazole dimer Biisobutyryl [4388-87-8] Bilarcil Bile acids... 

Molecular Interactions. Various polysaccharides readily associate with other substances, including bile acids and cholesterol, proteins, small organic molecules, inorganic salts, and ions. Anionic polysaccharides form salts and chelate complexes with cations some neutral polysaccharides form complexes with inorganic salts and some interactions are stmcture specific. Starch amylose and the linear branches of amylopectin form inclusion complexes with several classes of polar molecules, including fatty acids, glycerides, alcohols, esters, ketones, and iodine/iodide. The absorbed molecule occupies the cavity of the amylose helix, which has the capacity to expand somewhat to accommodate larger molecules. The starch—Hpid complex is important in food systems. Whether similar inclusion complexes can form with any of the dietary fiber components is not known. 

Dietary fiber and fiber-rich food fractions bind bile acids and bile salts in vitro. This interaction is more pronounced for the lignin component. 

Bile acids, which exist mainly as bile salts, are polar carboxylic acid derivatives of cholesterol that are important in the digestion of food, especially the solubilization of ingested fats. The Na and salts of glycocholic acid and tauro-cholic acid are the principal bile salts (Ligure 25.41). Glycocholate and tauro-cholate are conjugates of cholic acid with glycine and taurine, respectively. 

Chitosan for oral administration to humans is generally recognized as safe. In vitro, chitosan has been reported to bind bile acids The role of the accompanying anion is important for instance chitosan orotate salt has enhanced capacity for bile acids [11,264-267]. 

Although products of fat digestion, including cholesterol, are absorbed in the first 100 cm of small intestine, the primary and secondary bile acids are absorbed almost exclusively in the ileum, and 98—99% are returned to the liver via the portal circulation. This is known as the enterohepatic circulation (Figure 26—6). However, lithocholic acid, because of its insolubility, is not reabsorbed to any significant extent. Only a small fraction of the bile salts escapes absorption and is therefore eliminated in the feces. Nonetheless, this represents a major pathway for the elimination of cholesterol. Each day the small pool of bile acids (about 3-5 g) is cycled through the intestine six to ten times and an amount of bile acid equivalent to that lost in the feces is synthesized from cholesterol, so that a pool of bile acids of constant size is maintained. This is accomplished by a system of feedback controls. 

Similarly, dietary fibers are known to interact with bile acids in the intestinal limien and thus increase bile salt excretion in feces, resulting in decreased munbers... 

Separation of several bile acids and bile salts in dog bile identification by liquid- 71... 

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