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Identification of a novel N-carbamoyl glucuronide: In vitro, In vivo and mechanistic studies

Gunduz, Mithat and Argikar, Upendra and Baeschlin, Daniel and Ferreira, Suzie and Hosagrahara, Vinayak and Harriman, Shawn (2009) Identification of a novel N-carbamoyl glucuronide: In vitro, In vivo and mechanistic studies. Drug Metabolism and Disposition, 38 (3). pp. 361-367. ISSN 0090-9556

Abstract

1-[4-Aminomethyl-4-(3-chloro-phenyl
)-cyclohexyl]-tetrahydro-pyrimidin-2-one, 1, was developed as an inhibitor of dipeptidyl peptidase-4 enzyme (DPP-4). Biotransformation studies with 1 revealed the presence of an N-carbamoyl glucuronide metabolite (M1) in rat bile and urine. N-carbamoyl glucuronides are rarely observed, and little is understood regarding the mechanism of N-carbamoyl glucuronidation. The objectives of the current investigation were to elucidate the structure of the novel N-carbamoyl glucuronide, to investigate the mechanism of N-carbamoyl glucuronide formation in vitro using stable labeled CO2, UGT reaction phenotyping, and to assess whether M1 was formed to the same extent in vitro across species – mouse, rat, hamster, dog, monkey and human. Structure elucidation was carried out on a Thermo LTQ-Orbitrap® with accurate mass measurement and MSn capabilities. 13C-labeled carbon dioxide (13CO2) was used for identification of the mechanism of N-carbamoyl glucuronidation. Mechanistic studies with 13C-labeled CO2 in rat liver microsomes revealed that CO2 from the bicarbonate buffer (in equilibrium with exogenous CO2) may be responsible for the formation of M1. M1 was formed in vitro in liver microsomes from multiple species – mainly rat and hamster, followed by similar formation in dog, monkey, mouse, human. M1 could be detected in UGT1A1, UGT1A3 and UGT2B7 Supersomes® in a CO2 rich environment. In conclusion our study demonstrates that formation of M1 was observed in microsomal incubations across various species and strongly suggests the incorporation of CO2 from the bicarbonate buffer, in equilibrium with exogenous CO2 into the carbamoyl moiety of the formed N-carbamoyl glucuronide.

Item Type: Article
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Additional Information: Archiving not formally supported. Author cannot archive post-print (ie final draft post-refereeing)
Keywords: UGT; N-carbamoyl glucuronide; glucuronides; phenotyping
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Date Deposited: 13 Oct 2015 13:17
Last Modified: 13 Oct 2015 13:17
URI: https://oak.novartis.com/id/eprint/1519

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