Abstract
This article describes the biosynthesis and identification of a new class of metabolites, a piperazine N-oxide/N-glucuronide metabolite 4-[2-(2,4-dimethyl-phenylsulfanyl)-phenyl]-1-β-d-glucuronic acid-piperazine 1-oxide (4). The metabolite was found in urine and plasma from humans and animals dosed with 1-[2-(2,4-dimethyl-phenylsulfanyl)-phenyl]-piperazine hydrobromide (Lu AA21004, 1), as a novel multimodal antidepressant under development for treatment of depression. Human liver microsomes in combination with uridine 5′-diphosphoglucuronic acid were used as an in vitro system to generate enough material of 4 to perform one- and two-dimensional 1H and 13C NMR experiments for structure elucidation. Based on rotating frame Overhauser enhancement spectroscopy NMR experiments, the distance correlation between a piperazine proton and the anomeric proton of the glucuronic acid moiety is of a magnitude similar to that of the H-3′ and H-5′ protons and can only be explained by proximity in space and the postulated structure (4). The structural analog, the N-O-glucuronic acid conjugate 6-{4-[2-(2,4-dimethyl-phenylsulfanyl)-phenyl]-piperazin-1-yloxy}-1-β-d-glucuronic acid (3) was also observed in biological samples from humans and animals and the first organic synthesis and structural identification of this metabolite is also reported. Treatment of the glucuronide metabolites 3 and 4 with β-glucuronidase gave mainly the expected hydrolysis product, the hydroxyl amine 4-[2-(2,4-dimethyl-phenylsulfanyl)-phenyl]-piperazin-1-ol (2).
Footnotes
Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
doi:10.1124/dmd.111.040428.
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ABBREVIATIONS:
- NMP
- N-methyl-2-pyrrolidone
- UGT
- UDP-glucuronosyltransferase
- Lu AA21004
- 1-[2-(2,4-dimethyl-phenylsulfanyl)-phenyl]-piperazine hydrobromide
- HPLC
- high-performance liquid chromatography
- UDPGA
- UDP-diphosphoglucuronic acid
- MS
- mass spectrometry
- DMSO
- dimethyl sulfoxide
- THF
- tetrahydrofuran
- AcOEt
- ethyl acetate
- CDCl3
- chloroform-d
- HRMS
- high-resolution mass spectrometry
- MeOH
- methanol
- AcOH
- acetic acid
- TOCSY
- total correlation spectroscopy
- HSQC
- heteronuclear single quantum coherence
- HMBC
- heteronuclear multiple bond correlation
- ROESY
- rotating frame Overhauser enhancement spectroscopy.
- Received May 6, 2011.
- Accepted September 6, 2011.
- Copyright © 2011 by The American Society for Pharmacology and Experimental Therapeutics
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