Analysis of metabolic profiles of bile acids in urine using a lipophilic anion exchanger and computerized gas-liquid chromatorgaphy-mass spectrometry

Bile salts of vertebrates: structural variation and possible evolutionary significance.

Developmental changes in the composition and function of sarcoplasmic reticulum.

Metabolism of lithocholate in healthy man. II. Enterohepatic circulation.

Publisher Summary This chapter discusses the mechanism of bile-acid biosynthesis in mammalian liver. Generally, the most important pathway for the metabolism and excretion of cholesterol in mammals is the formation of bile acids. The major primary bile acids, cholic and chenodeoxycholic acid, are formed from cholesterol in the liver and secreted with bile to the intestine. The reactions involved are saturation of the double bond, epimerization of the 3β-hydroxyl group, introduction of hydroxyl groups into the 7α and 12α positions, oxidation of the C27, side chain to a C24-carboxylic acid, and conjugation with taurine or glycine. The sequence of these reactions has been studied extensively and the major pathways have been defined with a high degree of certainty in rat and man. After the secretion of the primary bile acids with bile to the intestine, microorganisms may transform them into secondary bile acids, such as deoxycholic and lithocholic acid. The major part of all bile acids in the intestine is absorbed and returns to the liver via the portal blood. Only a small fraction is excreted in the feces. The bile acids returning to the liver in the enterohepatic circulation may be further metabolized before they are reconjugated and re-excreted into the bile. The conversion of cholesterol into bile acids represents the most obvious example of the high capacity of the liver to convert lipid-soluble material into excretable water-soluble products.

Chapter 9 Mechanism of bile acid biosynthesis in mammalian liver

Bile acids. 28. Gas chromatography of new bile acids and their derivatives.

[5alpha,6alpha-3H2]-5alpha-Cholestane-3alpha,7alpha-diol (A), (25 R)-3alpha,7alpha-dihydroxyl-[5alpha,6alpha-3H2]-5alpha--cholestan-26-oic acid (B),(25R)-[5alpha,6alpha-3H2]stane-3alpha,7alpha-26-triol (C), and [3beta-3H]allochenodeoxycholic acid (D) were prepared, characterized, and studied with a rat liver microsomal preparation fortified with 1 mM NADPH. The 12alpha-hydroxylated product formed from each of these substrates was identified by isotopic dilution; the relative reactivity of the four substrates was (A) 100; (B) 87; (C) 135; and (D) 40. The microsomal system showed a requirement for added NADPH and other properties similar to those shown for 12alpha-hydroxylation of 7alpha-hydroxycholest-4-en-3-one, which is ultimately converted to cholic acid. Since the coplanar 5alpha-cholestane-3alpha,7alpha-diol is virtually superimposable upon 7alpha-hydroxycholest-4-en-3-one, and the enzymic requirements are comparable, it is suggested that a single enzyme system may be responsible for 12alpha-hydroxylation of these substrates.

Comparison of 12alpha-hydroxylation of oxygenated 5alpha-cholestanes and allochenodeoxycholate with rat liver microsomes.

Bile Acids XXXII. ALLOCHOLIC ACID, A METABOLITE OF ALLOCHENODEOXYCHOLIC ACID IN BILE FISTULA RATS

Bile acids XXXIII. The synthesis of allomuricholic acids

Bile acids XLII. Preparation of 5α-cholestan-26-oic acids from kryptogenin

Mei Mei Mui

Papers

Bile acids. 28. Gas chromatography of new bile acids and their derivatives.

Comparison of 12alpha-hydroxylation of oxygenated 5alpha-cholestanes and allochenodeoxycholate with rat liver microsomes.

Bile Acids XXXII. ALLOCHOLIC ACID, A METABOLITE OF ALLOCHENODEOXYCHOLIC ACID IN BILE FISTULA RATS

Bile acids XXXIII. The synthesis of allomuricholic acids

Bile acids XLII. Preparation of 5α-cholestan-26-oic acids from kryptogenin