Cholesterol cholic acid

Japanese quad exhibit greater plasma total cholesterol concentrations than rat counterparts when fed a similar, basal low-cholesterol diet (Table 1). Species differences in plasma lipids are more pronounced when fed an atherogenic diet (e.g., cholesterol/cholic acid supplemented and saturated fat-contaming diet), as evidenced by the marked elevations observed in quad plasma total cholesterol concentrations... 

There are two primary bile acids formed in the liver from cholesterol cholic acid and chenodeoxycholic acid. 

Dihydro-17-methyl-l5/f-cyclopenta[a]phenanthrene Diels hydrocarbon. C Hlt mol wt 232.33. C 93.06%, H 6.94%. Prepd from cholesterol, cholic acid, or suitable sapogenins Diels, Rickert, Ber, 60, 267 (]935) starting with 2 -acetyl -phenanthrene Gamble ef al. J. Chem, Soc. 1935, 443, 644. 

The liver secretes a elear, golden yellow viscous liquid known as bile . It is stored in gall bladder and is solely useful for the digestive system. It mainly consists of the inorganie ions like HCO3, Cl Na , K, etc., in addition to organic compoimds such as bile aeids, bile pigments, liquid fatty acids and cholesterol. Cholic Acid Deoxycholic Acid Chenodeoxycholic Acid. 

Figure 13 Comparison of imprinted electrode response to cholesterol (- -), cholic acid (- -), and deoxycholic acid (From Ref. 44.)...

Castor (Ricinus communis) oil Cellulose Cholesterol Cholic acid Choline bitartrate Choline chloride Citric acid esters of mono-and diglycerides of fatty acids Coconut (Cocos nucifera) oil Corn glycerides Corn (Zea mays) oil... 

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... 

As we have seen in this chapter steroids have a number of functions in human physiology Cholesterol is a component part of cell mem branes and is found in large amounts in the brain Derivatives of cholic acid assist the digestion of fats in the small intestine Cortisone and its derivatives are involved in maintaining the electrolyte balance in body fluids The sex hormones responsible for mascu line and feminine characteristics as well as numerous aspects of pregnancy from conception to birth are steroids... 

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. 

FIGURE 25.41 Cholic acid, a bile salt, is synthesized from cholesterol via 7o -hydroxy-cholesterol. Conjugation with taurine or glycine produces taurocholic acid and glycocholic acid, respectively. Taurocholate and glycocholate are freely water-soluble and are highly effective detergents. 

Galls tone-solubilizing (gallstone-dissolving) drugs, such as ursodiol (Actigall), suppress die manufacture of cholesterol and cholic acid by die liver. The suppression of die manufacture of cholesterol and cholic add may ultimately result in a decrease in die size of radiolucent gallstones. 

The primary bile acids are synthesized in the liver from cholesterol. These are cholic acid (found in the largest amount) and chenodeoxycholic acid (Figure 26-7). 

Desoxycholic Acid, Fatty Acids, Cholesterol.—The first alcoholic filtrate obtained during the crystallisation of the cholic acid (see above) is made strongly alkaline to phenolphthalein paper with 2 N-sodium hydroxide solution and concentrated to a syrupy consistency in a porcelain basin on the water bath. The syrup is taken up in 250 c.c. of water, transferred to a separating funnel, cooled, covered... 

Cholesterol exists in large amounts in aminal plasma membranes and reinforces the membrane structure cholic acids on the other hand destroy the membrane structure (Van Dijck et al, 1976). Synthetic bilayers can incorporate cholesterol molecules in appreciable amounts ( 50%) and the bound cholesterol appears to be aligned perpendicular to the plane of the... 

The broad-spectrum antibiotic chlorotetracycline and the aminoglycoside antibiotic kanamycin are observed to lower the cholesterol levels by forming salts with bile acids (e.g.. cholic acid, deoxycholic acid and chenodeoxycholic acid) in the intestinal canal,... 

Cholic acid and chenodeoxycholic acid, known as the primary bile acids, are quantitatively the most important metabolites of cholesterol. After being biosynthesized, they are mostly activated with coenzyme A and then conjugated with glycine or the non-pro-teinogenic amino acid taurine (see p. 62). The acid amides formed in this way are known as conjugated bile acids or bile salts. They are even more amphipathic than the primary products. 

Bile salts are exclusively synthesized in the liver (see A). The slowest step in their biosynthesis is hydroxylation at position 7 by a 7-a-hydroxylase. Cholic acid and other bile acids inhibit this reaction (end-product inhibition). In this way, the bile acids present in the liver regulate the rate of cholesterol utilization. 

Hydroxylation, shortening of the hydrocarbon chain, and addition of a carboxyl group convert cholesterol in a complex series of reactions to the bile acids, cholic acid, and chenodeoxycholic acid. 

In the bile cholesterol is kept soluble by fats, phospholipids like lecithin and by bile acids. The important bile acids in human bile are cholic acid, chen-odeoxycholic acid or chenodiol and ursodeoxycholic acid or ursodiol. Bile acids increase bile production. Dehydrocholic acid, a semisynthetic cholate is especially active in this respect. It stimulates the production of bile of low specific gravity and is therefore called a hydrocholeretic drug. Chenodiol and ursodiol but not cholic acid decrease the cholesterol content of bile by reducing cholesterol production and cholesterol secretion. Ursodiol also decreases cholesterol reabsorption. By these actions chenodiol and ursodiol are able to decrease the formation of cholesterolic gallstones and they can promote their dissolution. 

Steroids like cholesterol 335, cholic acid 336, or the sex hormone testosterone 337 play an important role in almost all living organisms. Therefore they are the... 

LeHoux and Grondin (1993) investigated the effects of chitosan on plasma and liver cholesterol levels, liver weight, and 3-hydroxy-3-methylglutaryl coenzyme A reductase in rats fed on a sterol diet (1% cholesterol and 0.2% cholic acid). Chitosan at a level of 5% lowered plasma and liver cholesterol levels by 54% and 64%, respectively. High MW chitosan (>750 kDa) had less hypocholesterolemic potential than that of 70 kDa. 

Primary BAs, cholic acid (CA), and chenodeoxycholic acid (CDCA), are synthesised via the 5/3-saturation of the cholesterol double bond by enzymes of the hepa-tocyte microsomal fraction, epimerisation of the 3/j-hydroxyl group to the 3a-con-figuration, and further insertion of a 7 -hydroxyl group, with or without a further 12a-hydroxyl group. After shortening of the side chain by three carbons, oxidation of the terminal carbon of the side chain occurs to form the carboxylic group [3]. Alternative metabolic sequences add to the complexity of this metabolic pathway (Fig. 5.4.2). 

Fig. 5.4.4a Methyl ester-trimethylsilyl (TMS) ethers of BAs from a plasma sample, b n-Butyl ester-TMS ethers of BAs from a plasma sample (adapted from [15]). 1 Nor-cholic acid, 2 litho-cholic acid, 3 deoxycholic acid, 4 chenodeoxycholic acid, 5 cholic acid, 6 ursodeoxycholic acid, a cholesterol, b sitosterol)...

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