1H NMR characterization of complexation of Glutathione with silver and aluminum metals in aqueous solution

Abstract

Metallo-elements have both pharmacological and toxic effects on plants, animals and humans. These are considered as a major public health issue worldwide. In particular, heavy metals such as silver (Ag) and aluminum (Al) are environmentally widespread, and their relative toxicity can lead to numerous pathologies such as nephropathy, cancers, vascular and skin diseases. The goal of this study was to examine the behavioral effects of Ag and Al salts (i.e. Silver nitrate and Aluminum sulfate) on glutathione (GSH), a potent oxidant in biological mixtures. We also aimed to suggest mechanisms of action of thiolate complexed to these metallo-elements in competitive studies with Ellman’s reagent (5,5’-dithiobis(2-nitrobenzoic acid aka ESSE). By proton nuclear magnetic resonance (NMR) spectroscopy, detailed titrations were carried out for these metal thiols interactions in the presence of ESSE in order to elucidate first equilibrium and possible second equilibrium. We found by 1H NMR spectroscopy that GSH binds to Ag and Al, which highlighted possible in-vivo chelation mechanisms of GSH toward these toxic metallo-elements.