Alio bile acids cholestanol

Conversion of cholestanol into alio bile acids... 

The origin of alio bile acids from cholestanol is clearly established (121, 36,28,122,40,123). After separation of two unidentified biliary acids similar to, but not identical with, cholic and chenodeoxycholic acids, Harold et al. 

If the pathway of biosynthesis of alio bile acids from cholestanol is similar to that proposed for the 5p bile acids from cholesterol, 7a-hydroxyla-tion should be the next step. The microsomal fraction of rat liver properly fortified with NADPH and oxygen was observed to hydroxylate cholestanol and cholesterol to the respective 7a-hydroxy derivatives at equivalent rates (127). With cholestanol the 7 -hydroxylase was inhibited by the product, or the 7j3-ol or 7-keto sterol. The rate of hydroxylation could be enhanced by prior treatment of the rats with cholestyramine (a bile acid sequestrant) and/or phenobarbital. A C5 double bond was not considered a requirement for enzymatic hydroxylation at C7. 

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