Reactions of the NO redox forms NO+, *NO and HNO (protonated NO-) with the melatonin metabolite N1-acetyl-5-methoxykynuramine.

The different NO redox forms, NO+, *NO and HNO (=protonated NO-), were compared for their capabilities of interacting with the melatonin metabolite N1-acetyl-5-methoxykynuramine (AMK), using NO+SbF6-, PAPA-NONOate and Angeli's salt as donors of the respective NO species. Particular attention was paid to stability and possible interconversions of the redox forms. *NO formation was followed by measuring the decolorization of 2-(trimethylammonio-phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (TMA-PTIO), at different pH values, at which NO+ is, in aqueous solution, either highly unstable (pH 7.