Identification of mono- and dihydroxy bile acids in human feces by gas-liquid chromatography and mass spectrometry

Abstract

The mono- and disubstituted cholanoic acids present in human feces have been investigated. Extracts of feces were fractionated on silicic acid column and individual bile acids were isolated by preparative thin-layer chromatography. The isolated compounds were studied by gas-liquid chromatography of the methyl esters, partial trimethylsilyl ethers, oxidation products, and trifluoroacetates. The probable structures deduced were confirmed by gas chromatography-mass spectrometry and by comparisons with authentic compounds.The following derivatives of 5Β-cholanoic acid not previously isolated from human feces were identified: 3,12-diketo, 3-keto-12α-hydroxy, 3α,l2Β-dihydroxy, 3Β,12Β-dihydroxy, 3-keto-7α-hydroxy, 3α-hydroxy-7-keto, 3Β,7α-dihydroxy, 3α,7α-dihydroxy, and 3α,7Β-dihydroxy.The presence of 3-keto-, 3Β-hydroxy-, 3α-hydroxy-, 3Β-hydroxy-12-keto-, 3α-hydroxy-12-keto-, 3Β,12α-dihydroxy-, and 3α,12α-dihydroxy-5Β-cholanoic acids was confirmed.Evidence was obtained for the presence of two bile acids having at least one hydroxyl group at a carbon atom other than C3, C7, or C12.

Keywords

• bile acids
• trifluoroacetates
• partial trimethylsilyl ethers
• dimethylhydrazones
• thin-layer chromatography
• gas-liquid chromatography