title: Synthesis of the 3-sulfates of S-acyl glutathione conjugated bile acids and their biotransformation by a rat liver cytosolic fraction.
abstract: The 3-sulfates of the S-acyl glutathione (GSH) conjugates of five natural bile acids (cholic, chenodeoxycholic, deoxycholic, ursodeoxycholic, and lithocholic) were synthesized as reference standards in order to investigate their possible formation by a rat liver cytosolic fraction. Their structures were confirmed by proton nuclear magnetic resonance, as well as by means of electrospray ionization-linear ion-trap mass spectrometry with negative-ion detection. Upon collision-induced dissociation, structurally informative product ions were observed. Using a triple-stage quadrupole instrument, selected reaction monitoring analyses by monitoring characteristic transition ions allowed the achievement of a highly sensitive and specific assay. This method was used to determine whether the 3-sulfates of the bile acid-GSH conjugates (BA-GSH) were formed when BA-GSH were incubated with a rat liver cytosolic fraction to which 3'-phosphoadenosine 5'-phosphosulfate had been added. The S-acyl linkage was rapidly hydrolyzed to form the unconjugated bile acid. A little sulfation of the GSH conjugates occurred, but greater sulfation at C-3 of the liberated bile acid occurred. Sulfation was proportional to the hydrophobicity of the unconjugated bile acid. Thus GSH conjugates of bile acids as well as their C-3 sulfates if formed in vivo are rapidly hydrolyzed by cytosolic enzymes.
authors.affiliation: Faculty of Pharmaceutical Sciences, Kinki University, Higashi-osaka, Japan.
authors.forename: Kuniko
authors.initials: K
authors.lastname: Mitamura
authors.forename: Naohiro
authors.initials: N
authors.lastname: Hori
authors.forename: Shiori
authors.initials: S
authors.lastname: Mino
authors.forename: Takashi
authors.initials: T
authors.lastname: Iida
authors.forename: Alan F
authors.initials: AF
authors.lastname: Hofmann
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ikegawa
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism*; D001711:Biotransformation; D060326:Chemistry Techniques, Synthetic; D003600:Cytosol / Q000378:metabolism*; D005978:Glutathione / Q000031:analogs & derivatives* / Q000737:chemistry; D008099:Liver / Q000166:cytology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013431:Sulfates / Q000737:chemistry*
chemical_list: D001647:Bile Acids and Salts; D013431:Sulfates; D005978:Glutathione