3-7-12-24-tetrahydroxycholestanoic-acid and 3-7-12-trihydroxycholestan-26-oic-acid

Four stereoisomers of 3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestan-26-oic acids were synthesized as possible intermediates of the side-chain degradation step of bile acid biosynthesis. 3 alpha,7 alpha,12 alpha-Trihydroxy-5 beta-cholest-25-en-24-one prepared by thermolysis of beta-ketosulfoxide was reduced to the (24R)- and (24S)-allylic alcohols by reduction with sodium borohydride. Each isomeric alcohol was subjected to hydroboration and oxidation to give (25R)- and (25S)-3 alpha,7 alpha,12 alpha,24,26-pentahydroxy-5 beta-cholestanes. The separated four stereoisomers were converted into the corresponding 26-carboxylic acids. The stereoisomers of 3 alpha,7 alpha,24-trihydroxy-5 beta-cholestan-26-oic acids were synthesized in the same manner. To establish the stereochemistry of these carboxylic acids, the chemical transformation of methyl 3 alpha,7 alpha,12 alpha-trihydroxy- and 3 alpha,7 alpha-dihydroxy-5 beta-cholest-24-en-26-oates into the above stereoisomers and the reductive dehydroxylation of the 24-hydroxyl group into known 3 alpha,7 alpha,12 alpha,26-tetrahydroxy- and 3 alpha,7 alpha,26-trihydroxy-5 beta-cholestanes are described. The applications of spectroscopic methods (circular dichroism and 1H nuclear magnetic resonance) to elucidation of the stereochemistry are also discussed.

Topics: Bile Acids and Salts; Cholestanols; Circular Dichroism; Isomerism; Magnetic Resonance Spectroscopy; Molecular Structure

Incubation of (25RS)-, (25R)- and (25S)-3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestan-26-oic acid (THCA, 6, 6a, 6b) and (24E)-3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholest-24-en-26-oic acid (7) with rat liver mitochondria gave all four stereoisomers (9a,9b,9c,9d) of 3 alpha,7 alpha,12 alpha,24-Tetrahydroxy-5 beta-cholestan-26-oic acid (TeHCA). The corresponding 27-nor analogs (10,11) were also converted non-stereoselectively to a 1:1 mixture of the epimeric 24-hydroxy compounds (12).

Topics: Animals; Cholestanols; Cholesterol; Cholic Acid; Cholic Acids; Chromatography, High Pressure Liquid; Gas Chromatography-Mass Spectrometry; Male; Mitochondria, Liver; Rats; Rats, Wistar; Stereoisomerism

Studies of the stereochemistry of the intermediates, 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholest-24-en-26-oic acid and 3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestan-26-oic acid, in the biosynthetic sequence between 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestan-26-oic acid and cholic acid have been undertaken. (25R)- or (25S)-3 alpha,7 alpha, 12 alpha-Trihydroxy-5 beta-cholestan-26-oic acid was incubated with rat liver homogenates. The reaction products were converted to p-bromophenacyl ester derivatives and the esters were analyzed by high-performance liquid chromatography. By comparison with authentic samples of two (24E)- and (24Z)-isomers of the alpha, beta-unsaturated acid and of four isomers at C-24 and C-25 of the beta-hydroxy acid, (24E)-3 alpha,7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oic acid and (24R,25S)-3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestan-26-oic acid were found to be formed from either (25R)- or (25S)-3 alpha,7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oic acid. No formation of the (24Z)-isomer of the trihydroxycholestenoic acid or the other three isomers of the tetrahydroxycholestanoic acid was detected. The findings are discussed in relation to the assumed pathway for side chain cleavage in cholic acid biosynthesis.

Topics: Animals; Cholestanols; Chromatography, High Pressure Liquid; Liver; Rats; Stereoisomerism; Tritium

Conversion of 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestanoic acid into 3 alpha, 7 alpha, 12 alpha 24-tetrahydroxy-5 beta-cholestanoic and cholic acids was catalyzed either by the mitochondrial fraction fortified with coenzyme A, ATP, MgCl2 and NAD or by the combination of microsomal fraction and 100,000 x g supernatant fluid fortified with coenzyme A, ATP and nad. 24-hydroxylation and formation of cholic acid occurred at similar rates with the 25R- and the 25S-forms of 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestanoic acid. The 25R- and 25S-forms of 3 alpha, 7 alpha, 12 alpha-trihydroxy- and 3 alpha, 7 alpha, 12 alpha, 24-tetrahydroxy-5 beta-cholestanoic acids were administered to bile fistula rats. Labeled cholic acid was isolated from the bile. The initial specific radioactivity of cholic acid was higher and the disappearance of radioactivity more rapid after administration of 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestanoic acid than of 3 alpha, 7 alpha, 12 alpha, 24-tetrahydroxy-5 beta-cholestanoic acid. The findings are discussed in relation to the assumed pathway for side chain cleavage in cholic acid biosynthesis.

Topics: Adenosine Triphosphate; Animals; Cholestanols; Cholic Acids; Coenzyme A; Liver; Male; Microsomes, Liver; Mitochondria, Liver; NAD; Rats; Subcellular Fractions