Bile alcohols lower vertebrates

Bile alcohols polyhydroxylated steroids structurally related to cholestane. They oecur as sulfate esters in the bile of lower vertebrates, e.g. scymmol (3a,7a,12a,24,25,27-hexahydroxy-5p-cholestane) from shark bile. 

II) Occurrence and structure of bile alcohols in lower vertebrates... 

Bile alcohols found in lower vertebrates are polyhydric derivatives of cholestane (C27), 27-norcholestane (C26), 26,27-dinorcholestane (C25) or cholane (C24). The trivial names of the bile alcohols include as a prefix part of the Latin name of the genus of the animal from which they were first isolated. When both isomers differing in the configuration at C-5 are known, the prefix 5a or 5)8 is then used with the... 

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. 

Studies on the biosynthesis of bile alcohols and primitive bile acids in lower vertebrates will provide additional information on the formation of the common bile acids in mammals and will help to clarify the molecular evolution of bile salts. However, such studies have been carried out only in a few species of lower vertebrates. 

Bile adds components of bile which serve as emuldfying agents. They are steroid carboxylic adds linked to taurine or glycine by a peptide bond. According to the constituent amino add, they are called glycocholic or taurocholic acids. Ihe former predominate in human and bovine bile, the latter in canine bile. B. a. are characteristic of mammals in lower vertebrates the same function is performed by Bile alcohols (see). In mammals, the pattern of B.a. is often spedfic for the spedes. 

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