Steroids cholic acid

Decahn ring systems appear as structural units m a large number of naturally occur ring substances particularly the steroids Cholic acid for example a steroid present m bile that promotes digestion incorporates as decahn and trans decahn units into a rather complex tetracyclic structure... 

Figure 26.5 Intercalation in sandwich-type inclusion crystals of steroidal cholic acid. Benzene derivatives undergo reversible desorption and absorption, accompanied by changes in bilayer distances.

Steroids are another class of natural products with multiple chirality centers One such compound is cholic acid which can be obtained from bile Its structural formula IS given m Figure 7 12 Cholic acid has 11 chirality centers and so a total (including cholic acid) of 2" or 2048 stereoisomers have this constitution Of these 2048 stereoiso mers how many are diastereomers of cholic acid s Remember Diastereomers are stereoisomers that are not enantiomers and any object can have only one mirror image Therefore of the 2048 stereoisomers one is cholic acid one is its enantiomer and the other 2046 are diastereomers of cholic acid Only a small fraction of these compounds are known and (+) cholic acid is the only one ever isolated from natural sources... 

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... 

The following mode) is that of cholic acid, a constituent of human bile. Locate the three hydroxyl groups, and identify each as axial or equatorial. Is cholic acid an A-B trans steroid or an A-B cis steroid ... 

CYP8A1 is the complementary enzyme to CYP5 in that it synthesizes prostacyclin in the arachidonic acid cascade. CYP8B1 catalyzes the steroid 12-alpha hydroxylation in the cholic acid biosynthesis. 

In contrast, the fluorescence spectra of the parent y-cyclodextrins (compounds y-CD1, y-CD2, y-CD3, y-CD4) exhibit both monomer and excimer bands in the absence of guests because the cavity is large enough to accommodate both fluorophores (Figure 10.38). The ratio of excimer and monomer bands changes upon guest inclusion. The ratio of the intensities of the monomer and excimer bands was used for detecting various cyclic alcohols and steroids (cyclohexanol, cyclo-dodecanol, i-borneol, 1-adamantanecarboxylic acid, cholic acid, deoxycholic acid and parent molecules, etc.). 

In order to increase structural diversity and to create a polar domain in the cage-like interior of these steroid/peptide macrocycles, dihydroxylated diacid 127 was synthesized in two steps from cholic acid (126) and reacted with diisonitrile 110, paraformaldehyde, and isopropylamine to form macrocycle 128 and its head-head isomer (Scheme 26). 

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... 

Pharmaceutical steroids are usually synthesized from cholic acid obtained from cattle or steroid sapogenins found in plants. Further modifications of these steroids have led to the marketing of a large group of synthetic steroids with special characteristics that are pharmacologically and therapeutically important (Table 39-1 Figure 39-3). 

The C>4 bile acids arise from cholesterol in the liver after saturation of the steroid nucleus and reduction in length of the side chain to a 5-carbon add they may differ in the number of hydroxyl groups on the sterol nucleus. The four acids isolated from human bile include cholic acid (3,7,12-tiihydroxy), as shown in Fig. 1 deoxycholic acid (2,12-dihydroxy) chenodeoxycholic acid (3,7-dihydroxy) and lithocholic acid (3-hydroxy). The bile acids are not excreted into the bile as such, but are conjugated through the C24 carboxylic add with glycine or... 

The stereochemistry of the B/C and C/D ring junctions are as in cholesterol and the cholic acids A/B stereochemistry is indicated where necessary. See p. 1474 for numbering system used for steroids. 

Scalia and Games developed a packed column SFC method for the analysis of free bile acids cholic acid (CA), chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), lithocholic acid (LCA), and ursodeoxycholic acid (UDCA) [32]. The baseline separation of all five bile acids was achieved on a packed phenyl column with a methanol-modified carbon dioxide in less than 4 min. The elution order showed a normal-phase mechanism because the solutes eluted in the order of increasing polarity following the number of hydroxyl groups on the steroid nucleus. The method was also applied to the assay of UDCA and CDCA in capsule and tablet formulations. The method was found to be linear in the range 1.5-7.5 ng/ml (r > 0.99, n = 6). The average recoveries (n= 10) for UDCA and CDCA were 100.2% with a RSD of 1.7% and 101.5% with a RSD of 2.2%, respectively. The reproducibility of the method was less than 1.5% (n = 10) for both UDCA and CDCA. 

Ox bile, which contains cholic acid as its principal constituent, provided one of the earliest mammalian sources of steroid raw materials for the commercial manufacture of the androgens. In nature, cholesterol itself is the mammalian precursor of the androgens, the biosynthesis passing through progesterone (XII). 

Sterols are steroids containing one or more hydroxyl groups. Some examples are cholesterol, a component of the cytoplasmic membrane of animal cells, testosterone, a hormone, and cholic acid. 

The bile acids are produced in the liver by the metabolism of cholesterol. They are di- and trihydroxylated steroids with 24 C atoms. The structure of cholic acid was seen earlier (Sec. 6.6). Deoxycholic acid and chenodeoxycholic acid are two other bile acids. In the bile acids, all the hydroxyl groups have an a orientation, while the two methyl groups are /3. Thus, one side of the molecule is more polar than the other. However, the molecules are not planar but bent because of the cis conformation of the A and B rings. 

Our study on the distribution of electron transferring proteins in animal sources is still in progress. From present knowledge, adrenodoxin can be found in adrenal cortexes from pig, beef, and rat. Further, a similar protein was isolated from pig testis (see II-A-2), and it was also found in the ovary. However, brain, heart, liver, kidney, and pancreas appear to lack adrenodoxin-like protein. If this is correct, the proteins of the ferredoxin family are located solely in the glands which directly act in the biosynthesis of steroid hormones. It is of interest that adrenodoxin-like protein does not participate in the steroid hydroxylation involved in cholesterol and cholic acid biosyntheses. All of these reactions without the participation of adrenodoxin are similar to enzymes responsible for microsomal non-specific hydroxylation, which consist of the following sequence of electron transfer ... 

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