In vitro Formation of Deoxycholic and Lithocholic Acid by Human Intestinal Microorganisms.

Abstract

The human intestinal microorganism responsible for removal of the 7-hydroxyl group from the bile acids can be subcultured anaerobically in Trypticase soy broth. The intestinal microorganisms have a high ability for removal of the 7-hydroxyl group from cholic as well as from cheno-deoxycholic acid. Centrifugation of the subcultures at 25,000 X g for 60 minutes reveals that the 2 reaction products appear in a different physical state. Deoxycholic acid appears in the supernatant whereas lithocholic acid Is recovered mainly in an acetone extract of the sediment. These results indicate that lithocholic acid formed in vivo in the human intestine probably is less accessible for absorption than deoxycholic acid and therefore is prevented from entering the enterohepatic circulation. This might also explain why lithocholic acid is found only in trace amounts in the human bile.