Melatonin: structural characterization of its non‐enzymatic mono‐oxygenate metabolite

Abstract

Oxidation of melatonin by Fenton reagents as well as with hypochlorous acid or oxoferryl hemoglobin has been investigated. Analysis of products by low resolution/mass spectra (MS), high resolution/MS, 1H-nuclear magnetic resonance (NMR), 13C-NMR, correlated spectroscopy (COSY) and heterocorrelated spectroscopy (HETCOR) 2D NMR reveals the formation of a single mono-oxygenated product under all conditions and unequivocally assigns the N-[2-(5-methoxy-2-oxo-2,3-dihydro-1H-indol-3-yl)-ethyl]-acetamide structure, which had not been previously considered.