Formation and biliary excretion of glutathione conjugates of bile acids in the rat as shown by liquid chromatography/electrospray ionization–linear ion trap mass spectrometry

• Published in: Analytical biochemistry Vol. 384; no. 2; pp. 224 - 230
• Main Authors: Mitamura, Kuniko, Watanabe, Saai, Mitsumoto, Yutaka, Sakai, Toshihiro, Sogabe, Mitsuru, Wakamiya, Tateaki, Ikegawa, Shigeo
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.01.2009
• Subjects: Acyl Coenzyme A - chemistry; Acyl Coenzyme A - metabolism; Acyl-adenylate; Acyl-CoA thioester; Animals; Bile - chemistry; Bile acid; Bile Acids and Salts - analysis; Bile Acids and Salts - chemistry; Bile Acids and Salts - metabolism; Catalysis; Chromatography, Liquid; Electrospray ionization; Glutathione - analysis; Glutathione - chemistry; Glutathione - metabolism; Glutathione conjugation; Glutathione S-transferase; Male; Mass spectrometry; Rats; Rats, Wistar; Spectrometry, Mass, Electrospray Ionization; Acyl-CoA thioester; Bile acid; Electrospray ionization; Acyl-adenylate; Glutathione S-transferase; Mass spectrometry; Glutathione conjugation
• ISSN: 0003-2697; 1096-0309
• DOI: 10.1016/j.ab.2008.09.040

Acyl-adenylates and acyl-CoA thioesters of bile acids (BAs) are reactive acyl-linked metabolites that have been shown to undergo transacylation-type reactions with the thiol group of glutathione (GSH), leading to the formation of thioester-linked GSH conjugates. In the current study, we examined the transformation of cholyl-adenylate (CA–AMP) and cholyl-coenzyme A thioester (CA–CoA) into a cholyl- S-acyl GSH (CA–GSH) conjugate by rat hepatic glutathione S-transferase (GST). The reaction product was analyzed by liquid chromatography (LC)/electrospray ionization (ESI)–linear ion trap mass spectrometry (MS). The GST-catalyzed formation of CA–GSH occurred with both CA–AMP and CA–CoA. Ursodeoxycholic acid, lithocholic acid, and 2,2,4,4- 2H 4-labeled lithocholic acid were administered orally to biliary fistula rats, and their corresponding GSH conjugates were identified in bile by LC/ESI–MS 2. These in vitro and in vivo studies confirm a new mode of BA conjugation in which BAs are transformed into their GSH conjugates via their acyl-linked intermediary metabolites by the catalytic action of GST in the liver, and the GSH conjugates are then excreted into the bile.