Online H/D exchange liquid chromatography as a support for the mass spectrometric identification of the oxidation products of melatonin |
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| Authors: | Fabrice Collin Dominique Bonnefont‐Rousselot Saï Yous Catherine Marchetti Daniel Jore Monique Gardès‐Albert |
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| Institution: | 1. Laboratoire de Chimie‐Physique, CNRS UMR 8601, Université Paris Descartes, 45 rue des Saints‐Pères, 75006 Paris, France;2. Laboratoire de Biochimie Métabolique et Clinique (EA 3617), Université Paris Descartes, 4 avenue de l'Observatoire, 75006 Paris, France;3. UF de Biochimie des Maladies Métaboliques, Service de Biochimie Métabolique, Batiment Benjamin Delessert, H?pital de La Pitié (AP‐HP), 83 boulevard de l'H?pital, 75013 Paris, France;4. Institut de Chimie Pharmaceutique, Université de Lille 2, Rue du Professeur Laguesse, BP 83, 59006 Lille, France |
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| Abstract: | The hydrogen–deuterium exchange of protonated melatonin and its in vitro oxidation end‐products have been examined by liquid chromatography coupled with ion‐trap mass spectrometry. Specific H/D scrambling of protons in the C2 and C4 positions of the indole ring during gas‐phase fragmentation process was observed for both melatonin and its oxidation products. Collision‐induced dissociation spectra showed losses of variably deuterated NH3, H2O and CH3CONH2. In addition, a similar H/D scrambling behaviour was observed for the oxidation products, obtained from the opening of the indole ring by oxidative attack. Fragmentation pathways are proposed and H/D scrambling has been employed as a fingerprint, allowing identification of N1‐acetyl‐5‐methoxykynurenin (AMK), N1‐acetyl‐N2‐formyl‐5‐methoxykynurenin (AFMK), dehydro‐AFMK and hydroxymelatonin as the oxidation products of melatonin in vitro. Copyright © 2008 John Wiley & Sons, Ltd. |
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| Keywords: | melatonin hydroxyl radicals deuterium exchange liquid chromatography mass spectrometry oxidation |
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