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Gu C, Lewis RJ, Wells AS, Svensson PH, Hosagrahara VP, Johnsson E, Hallström G. Lipid Peroxide-Mediated Oxidative Rearrangement of the Pyrazinone Carboxamide Core of Neutrophil Elastase Inhibitor AZD9819 in Blood Plasma Samples. Drug Metab Dispos 2015. [PMID: 26203069 DOI: 10.1124/dmd.115.065136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
This study focused on the mechanistic interpretation of ex vivo oxidation of a candidate drug in blood plasma samples. An unexpected lipid peroxide-mediated epoxidation followed by a dramatic rearrangement led to production of a five-membered oxazole derivative from the original six-membered pyrazinone-carboxamide core of a human neutrophil elastase inhibitor, 6-(1-(4-cyanophenyl)-1H-pyrazol-5-yl)-N-ethyl-5-methyl-3-oxo-4-(3-(trifluoromethyl)phenyl)-3,4-dihydropyrazine-2-carboxamide (AZD9819). The rearranged oxidation product 2-(1-(4-cyanophenyl)-1H-pyrazol-5-yl)-5-(N-ethylacetamido)-N-(3-(trifluoromethyl)phenyl)oxazole-4-carboxamide was characterized by accurate-mass tandem mass spectrometry fragmentations, by two-dimensional NMR and X-ray crystallography of an authentic standard, and by incorporation of an (18)O atom from molecular (18)O2 to the location predicted by our proposed mechanism. The lipid peroxide-mediated oxidation was demonstrated by using human low-density lipoprotein (LDL) in pH 7.4 phosphate buffer and by inhibiting the oxidation with ascorbic acid or l-glutathione, two antioxidants effective in both plasma and the LDL incubation. A nucleophilic mechanism for the epoxidation of AZD9819 by lipid hydroperoxides explains the prevention of its ex vivo oxidation by acidification of the plasma samples. The discovery of the lipid peroxide-dependent oxidation of an analyte and the means of prevention could provide valuable information for biotransformation and bioanalysis.
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Affiliation(s)
- Chungang Gu
- AstraZeneca, R&D Boston, Waltham, Massachusetts (C.G., V.P.H.); AstraZeneca, R&D Mölndal, Mölndal, Sweden (R.J.L., E.J.); AstraZeneca, R&D Charnwood, Loughborough, United Kingdom (R.J.L., A.S.W.); AstraZeneca, R&D Södertälje, Södertälje, Sweden (P.H.S); AstraZeneca, R&D Wilmington, Wilmington, Delaware (C.G.); AstraZeneca, R&D Lund, Lund, Sweden (E.J., G.H.); SP Process Development, Södertälje, Sweden (P.H.S.); and Applied Physical Chemistry, Royal Institute of Technology, Stockholm, Sweden (P.H.S.)
| | - Richard J Lewis
- AstraZeneca, R&D Boston, Waltham, Massachusetts (C.G., V.P.H.); AstraZeneca, R&D Mölndal, Mölndal, Sweden (R.J.L., E.J.); AstraZeneca, R&D Charnwood, Loughborough, United Kingdom (R.J.L., A.S.W.); AstraZeneca, R&D Södertälje, Södertälje, Sweden (P.H.S); AstraZeneca, R&D Wilmington, Wilmington, Delaware (C.G.); AstraZeneca, R&D Lund, Lund, Sweden (E.J., G.H.); SP Process Development, Södertälje, Sweden (P.H.S.); and Applied Physical Chemistry, Royal Institute of Technology, Stockholm, Sweden (P.H.S.)
| | - Andrew S Wells
- AstraZeneca, R&D Boston, Waltham, Massachusetts (C.G., V.P.H.); AstraZeneca, R&D Mölndal, Mölndal, Sweden (R.J.L., E.J.); AstraZeneca, R&D Charnwood, Loughborough, United Kingdom (R.J.L., A.S.W.); AstraZeneca, R&D Södertälje, Södertälje, Sweden (P.H.S); AstraZeneca, R&D Wilmington, Wilmington, Delaware (C.G.); AstraZeneca, R&D Lund, Lund, Sweden (E.J., G.H.); SP Process Development, Södertälje, Sweden (P.H.S.); and Applied Physical Chemistry, Royal Institute of Technology, Stockholm, Sweden (P.H.S.)
| | - Per H Svensson
- AstraZeneca, R&D Boston, Waltham, Massachusetts (C.G., V.P.H.); AstraZeneca, R&D Mölndal, Mölndal, Sweden (R.J.L., E.J.); AstraZeneca, R&D Charnwood, Loughborough, United Kingdom (R.J.L., A.S.W.); AstraZeneca, R&D Södertälje, Södertälje, Sweden (P.H.S); AstraZeneca, R&D Wilmington, Wilmington, Delaware (C.G.); AstraZeneca, R&D Lund, Lund, Sweden (E.J., G.H.); SP Process Development, Södertälje, Sweden (P.H.S.); and Applied Physical Chemistry, Royal Institute of Technology, Stockholm, Sweden (P.H.S.)
| | - Vinayak P Hosagrahara
- AstraZeneca, R&D Boston, Waltham, Massachusetts (C.G., V.P.H.); AstraZeneca, R&D Mölndal, Mölndal, Sweden (R.J.L., E.J.); AstraZeneca, R&D Charnwood, Loughborough, United Kingdom (R.J.L., A.S.W.); AstraZeneca, R&D Södertälje, Södertälje, Sweden (P.H.S); AstraZeneca, R&D Wilmington, Wilmington, Delaware (C.G.); AstraZeneca, R&D Lund, Lund, Sweden (E.J., G.H.); SP Process Development, Södertälje, Sweden (P.H.S.); and Applied Physical Chemistry, Royal Institute of Technology, Stockholm, Sweden (P.H.S.)
| | - Eskil Johnsson
- AstraZeneca, R&D Boston, Waltham, Massachusetts (C.G., V.P.H.); AstraZeneca, R&D Mölndal, Mölndal, Sweden (R.J.L., E.J.); AstraZeneca, R&D Charnwood, Loughborough, United Kingdom (R.J.L., A.S.W.); AstraZeneca, R&D Södertälje, Södertälje, Sweden (P.H.S); AstraZeneca, R&D Wilmington, Wilmington, Delaware (C.G.); AstraZeneca, R&D Lund, Lund, Sweden (E.J., G.H.); SP Process Development, Södertälje, Sweden (P.H.S.); and Applied Physical Chemistry, Royal Institute of Technology, Stockholm, Sweden (P.H.S.)
| | - Gösta Hallström
- AstraZeneca, R&D Boston, Waltham, Massachusetts (C.G., V.P.H.); AstraZeneca, R&D Mölndal, Mölndal, Sweden (R.J.L., E.J.); AstraZeneca, R&D Charnwood, Loughborough, United Kingdom (R.J.L., A.S.W.); AstraZeneca, R&D Södertälje, Södertälje, Sweden (P.H.S); AstraZeneca, R&D Wilmington, Wilmington, Delaware (C.G.); AstraZeneca, R&D Lund, Lund, Sweden (E.J., G.H.); SP Process Development, Södertälje, Sweden (P.H.S.); and Applied Physical Chemistry, Royal Institute of Technology, Stockholm, Sweden (P.H.S.)
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