Lipid Peroxide-Mediated Oxidative Rearrangement of the Pyrazinone Carboxamide Core of Neutrophil Elastase Inhibitor AZD9819 in Blood Plasma Samples
| Autor: | Vinayak P. Hosagrahara, Gösta Hallström, Per H. Svensson, Andrew S. Wells, Chungang Gu, Richard J. Lewis, Eskil Johnsson |
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| Rok vydání: | 2015 |
| Předmět: |
Male
Lipid Peroxides medicine.drug_class Stereochemistry Proteinase Inhibitory Proteins Secretory Pharmaceutical Science Carboxamide chemistry.chemical_compound medicine Animals Humans Rats Wistar Oxazole Pharmacology Trifluoromethyl Lipid peroxide biology Ascorbic acid Amides Rats Elastase inhibitor chemistry Neutrophil elastase Pyrazines biology.protein Pyrazoles Female Oxidation-Reduction Ex vivo |
| Zdroj: | Drug metabolism and disposition: the biological fate of chemicals. 43(10) |
| ISSN: | 1521-009X |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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