197895-54-8Relevant articles and documents
UGT-dependent regioselective glucuronidation of ursodeoxycholic acid and obeticholic acid and selective transport of the consequent acyl glucuronides by OATP1B1 and 1B3
Zhou, Dandan,Kong, Linghua,Jiang, Yiguo,Wang, Cheng,Ni, Yao,Wang, Yedong,Zhang, Hongjian,Ruan, Jianqing
, (2019/07/12)
Ursodeoxycholic acid (UDCA) is a major effective constituent of bear bile powder, which is widely used as function food in China and is documented in the Chinese pharmacopoeia as a traditional Chinese medicine. UDCA has been developed as the only accepted therapy by the US FDA for primary biliary cholangitis. Recently, the US FDA granted accelerated approval to obeticholic acid (OCA), a semisynthetic bile acid derivative from chenodeoxycholic acid, for primary biliary cholangitis. However, some perplexing toxicities of UDCA have been reported in the clinic. The present work aimed to investigate the difference between UDCA and OCA in regard to potential metabolic activation through acyl glucuronidation and hepatic accumulation of consequent acyl glucuronides. Our results demonstrated that the metabolic fates of UDCA and OCA were similar. Both UDCA and OCA were predominantly metabolically activated by conjugation to the acyl glucuronide in human liver microsomes. UGT1A3 played a predominant role in the carboxyl glucuronidation of both UDCA and OCA, while UGT2B7 played a major role in their hydroxyl glucuronidation. Further uptake studies revealed that OATP1B1- and 1B3-transfected cells could selectively uptake UDCA acyl glucuronide, but not UDCA, OCA, and OCA acyl glucuronide. In summary, the liver disposition of OCA is different from that of UDCA due to hepatic uptake, and liver accumulation of UDCA acyl glucuronide might be related to the perplexing toxicities of UDCA.
Glycoside cleavage by a new mechanism in unsaturated glucuronyl hydrolases
Jongkees, Seino A. K.,Withers, Stephen G.
, p. 19334 - 19337 (2012/01/31)
Unsaturated glucuronyl hydrolases (UGLs) from GH family 88 of the CAZy classification system cleave a terminal unsaturated sugar from the oligosaccharide products released by extracellular bacterial polysaccharide lyases. This pathway, which is involved in extracellular bacterial infection, has no equivalent in mammals. A novel mechanism for UGL has previously been proposed in which the enzyme catalyzes hydration of a vinyl ether group in the substrate, with subsequent rearrangements resulting in glycosidic bond cleavage. However, clear evidence for this mechanism has been lacking. In this study, analysis of the products of UGL-catalyzed reactions in water, deuterium oxide, and dilute methanol in water, in conjunction with the demonstration that UGL rapidly cleaves thioglycosides and glycosides of inverted anomeric configuration (substrates that are resistant to hydrolysis by classical glycosidases), provides strong support for this new mechanism. A hydration-initiated process is further supported by the observed UGL-catalyzed hydration of a C-glycoside substrate analogue. Finally, the observation of a small β-secondary kinetic isotope effect suggests a transition state with oxocarbenium ion character, in which the hydrogen at carbon 4 adopts an axial geometry. Taken together, these observations validate the novel vinyl ether hydration mechanism and are inconsistent with either inverting or retaining direct hydrolase mechanisms at carbon 1.
Intermediates for Glucuronide Synthesis: 7-Hydroxycoumarin Glucuronide
Brown, Richard T.,Scheinmann, Feodor,Stachulski, Andrew V.
, p. 370 - 371 (2007/10/03)
A convenient synthesis of the important metabolite 7-hydroxycoumarin glucuronide 3 is presented, including a first report of the β-imidate 11β, together with new preparations of the iodosugar 6 and α-imidate 11α: stability data on 11α and 11β are also given, and the importance of carefully controlled hydrolysis in the last step of the preparation of 3 is emphasised.
