POSITIONS OF CONJUGATION OF BILE-ACIDS WITH GLUCOSE AND N-ACETYLGLUCOSAMINE IN-VITRO

In order to establish the position of conjugation of bile acids with g lucose or N-acetylglucosamine, glucosides of chenodeoxycholic and hyod eoxycholic acids and of C-13-labeled cholic, lithocholic, chenodeoxych olic, hyodeoxycholic, and ursodeoxycholic acids, and N-acetylglucosami nides of ursodeoxycholic, isoursodeoxycholic, 3-dehydro-ursodeoxycholi c, and ursodeoxycholylglycine were synthesized in vitro. The conjugate s were purified by anion-exchange chromatography and reversed phase HL PC and were analyzed by gas chromatography-mass spectrometry. The gluc osides of chenodeoxycholic and hyodeoxycholic acids were also analyzed after periodate and chronic acid oxidation. All conjugates were analy zed by fast atom bombardment mass spectrometry with collision-induced dissociation. Glucose conjugation was shown to occur at C-3 in all bil e acid glucosides studied. In contrast, the selective N-acetylglucosam inidation of 7 beta-hydroxy bile acids was shown to occur at the 7 bet a-position.