Chenodeoxycholic acid, ursodeoxycholic acid and 7-ketolithocholic acid were incubated with human intestinal bacteria (source: 4 healthy males) at 37‡C for 72 hours in an anaerobic condition. The bile acids of the products in culture medium were identified by three independent methods, thin layer chromatography, gas-liquid chromatography and GLC-mass spectrometry.
Lithocholic acid, ursodeoxycholic acid and 7-ketolithocholic acid were observed in the culture of chenodeoxycholic acid. Lithocholic acid, chenodeoxycholic acid and 7-ketolithocholic acid were observed in the culture of ursodeoxycholic acid. Chenodeoxycholic acid and ursodeoxycholic acid were produced from 7-ketolithocholic acid. These data may suggest that chenodeoxycholic acid and ursodeoxycholic acid are interconvertible via 7-ketolithocholic acid by the mixed culture of human intestinal microorganisms under an anaerobic condition.