Mechanism of intestinal 7 alpha-dehydroxylation of cholic acid: evidence that allo-deoxycholic acid is an inducible side-product. 1991

P B Hylemon, and P D Melone, and C V Franklund, and E Lund, and I Björkhem
Department of Microbiology and Immunology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298.

We previously reported that the 7 alpha-dehydroxylation of cholic acid appears to be carried out by a multi-step pathway in intestinal anaerobic bacteria both in vitro and in vivo. The pathway is hypothesized to involve an initial oxidation of the 3 alpha-hydroxy group and the introduction of a double bond at C4-C5 generating a 3-oxo-4-cholenoic bile acid intermediate. The loss of water generates a 3-oxo-4,6-choldienoic bile acid which is reduced (three steps) yielding deoxycholic acid. We synthesized, in radiolabel, the following putative bile acid intermediates of this pathway 7 alpha,12 alpha-dihydroxy-3-oxo-4-cholenoic acid, 7 alpha,12 alpha-dihydroxy-3-oxo-5 beta-cholanoic acid, 12 alpha-dihydroxy-3-oxo-4,6-choldienoic acid, and 12 alpha-hydroxy-3-oxo-4-cholenoic acid and showed that they could be converted to 3 alpha,12 alpha-dihydroxy-5 beta-cholanoic acid (deoxycholic acid) by whole cells or cell extracts of Eubacterium sp. VPI 12708. During studies of this pathway, we discovered the accumulation of two unidentified bile acid intermediates formed from cholic acid. These bile acids were purified by thin-layer chromatography and identified by gas-liquid chromatography-mass spectrometry as 12 alpha-hydroxy-3-oxo-5 alpha-cholanoic acid and 3 alpha,12 alpha-dihydroxy-5 alpha-cholanoic (allo-deoxycholic acid). Allo-deoxycholic acid was formed only in cell extracts prepared from bacteria induced by cholic acid, suggesting that their formation may be a branch of the cholic acid 7 alpha-dehydroxylation pathway in this bacterium.

UI MeSH Term Description Entries
D007413 Intestinal Mucosa Lining of the INTESTINES, consisting of an inner EPITHELIUM, a middle LAMINA PROPRIA, and an outer MUSCULARIS MUCOSAE. In the SMALL INTESTINE, the mucosa is characterized by a series of folds and abundance of absorptive cells (ENTEROCYTES) with MICROVILLI. Intestinal Epithelium,Intestinal Glands,Epithelium, Intestinal,Gland, Intestinal,Glands, Intestinal,Intestinal Gland,Mucosa, Intestinal
D007422 Intestines The section of the alimentary canal from the STOMACH to the ANAL CANAL. It includes the LARGE INTESTINE and SMALL INTESTINE. Intestine
D008401 Gas Chromatography-Mass Spectrometry A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds. Chromatography, Gas-Liquid-Mass Spectrometry,Chromatography, Gas-Mass Spectrometry,GCMS,Spectrometry, Mass-Gas Chromatography,Spectrum Analysis, Mass-Gas Chromatography,Gas-Liquid Chromatography-Mass Spectrometry,Mass Spectrometry-Gas Chromatography,Chromatography, Gas Liquid Mass Spectrometry,Chromatography, Gas Mass Spectrometry,Chromatography, Mass Spectrometry-Gas,Chromatography-Mass Spectrometry, Gas,Chromatography-Mass Spectrometry, Gas-Liquid,Gas Chromatography Mass Spectrometry,Gas Liquid Chromatography Mass Spectrometry,Mass Spectrometry Gas Chromatography,Spectrometries, Mass-Gas Chromatography,Spectrometry, Gas Chromatography-Mass,Spectrometry, Gas-Liquid Chromatography-Mass,Spectrometry, Mass Gas Chromatography,Spectrometry-Gas Chromatography, Mass,Spectrum Analysis, Mass Gas Chromatography
D002793 Cholic Acids The 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholanic acid family of bile acids in man, usually conjugated with glycine or taurine. They act as detergents to solubilize fats for intestinal absorption, are reabsorbed by the small intestine, and are used as cholagogues and choleretics. Cholalic Acids,Acids, Cholalic,Acids, Cholic
D002855 Chromatography, Thin Layer Chromatography on thin layers of adsorbents rather than in columns. The adsorbent can be alumina, silica gel, silicates, charcoals, or cellulose. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Chromatography, Thin-Layer,Thin Layer Chromatography,Chromatographies, Thin Layer,Chromatographies, Thin-Layer,Thin Layer Chromatographies,Thin-Layer Chromatographies,Thin-Layer Chromatography
D003840 Deoxycholic Acid A bile acid formed by bacterial action from cholate. It is usually conjugated with glycine or taurine. Deoxycholic acid acts as a detergent to solubilize fats for intestinal absorption, is reabsorbed itself, and is used as a choleretic and detergent. Deoxycholate,Desoxycholic Acid,Kybella,Choleic Acid,Deoxycholic Acid, 12beta-Isomer,Deoxycholic Acid, 3beta-Isomer,Deoxycholic Acid, 5alpha-Isomer,Deoxycholic Acid, Disodium Salt,Deoxycholic Acid, Magnesium (2:1) Salt,Deoxycholic Acid, Monoammonium Salt,Deoxycholic Acid, Monopotassium Salt,Deoxycholic Acid, Monosodium Salt,Deoxycholic Acid, Sodium Salt, 12beta-Isomer,Dihydroxycholanoic Acid,Lagodeoxycholic Acid,Sodium Deoxycholate,12beta-Isomer Deoxycholic Acid,3beta-Isomer Deoxycholic Acid,5alpha-Isomer Deoxycholic Acid,Deoxycholate, Sodium,Deoxycholic Acid, 12beta Isomer,Deoxycholic Acid, 3beta Isomer,Deoxycholic Acid, 5alpha Isomer
D005051 Eubacterium A genus of gram-positive, rod-shaped bacteria found in cavities of man and animals, animal and plant products, infections of soft tissue, and soil. Some species may be pathogenic. No endospores are produced. The genus Eubacterium should not be confused with EUBACTERIA, one of the three domains of life. Butyribacterium
D006900 Hydroxylation Placing of a hydroxyl group on a compound in a position where one did not exist before. (Stedman, 26th ed) Hydroxylations
D001647 Bile Acids and Salts Steroid acids and salts. The primary bile acids are derived from cholesterol in the liver and usually conjugated with glycine or taurine. The secondary bile acids are further modified by bacteria in the intestine. They play an important role in the digestion and absorption of fat. They have also been used pharmacologically, especially in the treatment of gallstones. Bile Acid,Bile Salt,Bile Salts,Bile Acids,Acid, Bile,Acids, Bile,Salt, Bile,Salts, Bile
D019826 Cholic Acid A major primary bile acid produced in the liver and usually conjugated with glycine or taurine. It facilitates fat absorption and cholesterol excretion. Cholbam

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