7-ketolithocholic-acid and 7-ketodeoxycholic-acid

Secondary bile acid-producing bacteria were isolated from human feces to improve our appreciation of the functional diversity and redundancy of the intestinal microbiota. In total, 619 bacterial colonies were isolated using a nutrient-poor agar medium and the level of secondary bile acid formation was examined in each by a liquid culture, followed by thin-layer chromatography. Of five strains analyzed by 16S rRNA gene sequencing and biochemical testing, one was identified as Bacteroides intestinalis AM-1, which was not previously recognized as a secondary bile-acid producer. GC-MS revealed that B. intestinalis AM-1 converts cholic acid (CA) and chenodeoxycholic acid into their 7-oxo derivatives, 7-oxo-deoxycholic acid (7-oxo-DCA) and 7-oxo-lithocholic acid, respectively. Thus, B. intestinalis AM-1 possesses 7alpha-hydroxysteroid dehydrogenase (7alpha-HSDH) activity. In liquid culture, B. intestinalis AM-1 showed a relatively higher productivity of 7-oxo-DCA than Escherichia coli HB101 and Bacteroides fragilis JCM11019(T), which are known to possess 7alpha-HSDH activity. The level of 7alpha-HSDH activity was higher in B. intestinalis AM-1 than in the other two strains under the conditions tested. The 7alpha-HSDH activity in each of the three strains is not induced by CA; instead, it is regulated in a growth phase-dependent manner.

Topics: Adult; Bacterial Typing Techniques; Bacteroides; Bacteroides fragilis; Biotransformation; Chenodeoxycholic Acid; Cholic Acid; Chromatography, Thin Layer; Culture Media; Deoxycholic Acid; DNA, Bacterial; DNA, Ribosomal; Escherichia coli; Feces; Female; Humans; Lithocholic Acid; Male; Phylogeny; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Young Adult

The metabolism of 7-oxolithocholic acid and 7-oxodeoxycholic acid in isolated perfused rat livers was compared. The metabolites extracted from the bile of perfused livers were analysed by gas chromatography. The amount of bile acids excreted in bile was greater after infusion with 7-oxolithocholic acid than with 7-oxodeoxycholic acid. When 7-oxolithocholic acid was infused almost all of the bile acids excreted in bile were taurine conjugates; with 7-oxodeoxycholic acid about 10 percent remained unconjugated. 7-Oxolithocholic acid was more susceptible to reduction than 7-oxodeoxycholic acid. 7-Oxolithocholic acid was preferably reduced to 7 beta-hydroxy rather than to 7 alpha-hydroxy metabolites. In contrast, 7-oxodeoxycholic acid was reduced predominantly to the 7 alpha-hydroxy rather than to the 7 beta-hydroxy metabolite.

Topics: Animals; Bile; Bile Acids and Salts; Deoxycholic Acid; Hydroxylation; In Vitro Techniques; Lithocholic Acid; Liver; Male; Rats; Rats, Inbred Strains

3 alpha-Hydroxysteroid dehydrogenase (SDH) quantifies ursodeoxycholic acid, 3 alpha,12 alpha-diol-7-one-5 beta-cholanoic acid, 3 alpha-ol-7-one-5 beta-cholanoic acid, and 3 alpha,7 alpha-diol-12-one-5 beta-cholanoic acid in a manner similar to the more commonly measured bile acids, exemplified by taurocholic acid. The type of oxygen function at the 7 or 12 position and its orientation at the 7 position has no effect on the rate of reaction of the enzyme. Discrepancies in the glycine/taurine ratios of patient intestinal aspirates containing ursodeoxycholic acid and oxo bile acids, obtained by SDH and gas-liquid chromatographic methods are not a result of the enzyme assay procedure.

Topics: 3-Hydroxysteroid Dehydrogenases; Bile; Bile Acids and Salts; Chenodeoxycholic Acid; Cholic Acids; Chromatography, Gas; Deoxycholic Acid; Glycine; Humans; Intestines; Lithocholic Acid; Taurine; Ursodeoxycholic Acid