Identification of a novel conjugate in human urine: bile acid acyl galactosides.
We report a novel conjugate, bile acid acyl galactosides, which exist in the urine of healthy volunteers. To identify the two unknown peaks obtained in urine specimens from healthy subjects, the specimens were subjected to solid phase extraction and then to liquid chromatographic separation. The eluate corresponding to the unknown peaks on the chromatogram was collected. Following alkaline hydrolysis and liquid chromatography (LC)/electrospray ionization (ESI)-mass spectrometric (MS) analysis, cholic acid (CA) and deoxycholic acid (DCA) were identified as liberated bile acids. When a portion of the alkaline hydrolyzate was subjected to a derivatization reaction with 1-phenyl-3-methyl-5-pyrazolone, a derivative of galactose was detected by LC/ESI-MS. Finally, the liquid chromatographic and mass spectrometric properties of these unknown compounds in urine specimens were compared to those of authentic specimens and the structures were confirmed as CA 24-galactoside and DCA 24-galactoside. These results strongly imply that bile acid 24-galactosides, a novel conjugate, were synthesized in the human body.
Goto
Takaaki
T
Graduate School of Pharmaceutical Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai 980-8578, Japan.
Shibata
Akihiro
A
Sasaki
Daisuke
D
Suzuki
Naoto
N
Hishinuma
Takanori
T
Kakiyama
Genta
G
Iida
Takashi
T
Mano
Nariyasu
N
Goto
Junichi
J
D000328:Adult; D001647:Bile Acids and Salts / Q000737:chemistry / Q000652:urine*; D019826:Cholic Acid / Q000378:metabolism; D002853:Chromatography, Liquid; D003840:Deoxycholic Acid / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D005697:Galactosides / Q000652:urine*; D006801:Humans; D006868:Hydrolysis; D008297:Male; D008875:Middle Aged; D008956:Models, Chemical; D021241:Spectrometry, Mass, Electrospray Ionization; D013053:Spectrophotometry; D013997:Time Factors
D001647:Bile Acids and Salts; D005697:Galactosides; D003840:Deoxycholic Acid; D019826:Cholic Acid; D005690:Galactose