Ergothioneine products derived by superoxide oxidation in endothelial cells exposed to high-glucose

• Published in: Free radical biology & medicine 2017-07, Vol.108, p.8-18
• Main Authors: Servillo, Luigi, D’Onofrio, Nunzia, Casale, Rosario, Cautela, Domenico, Giovane, Alfonso, Castaldo, Domenico, Balestrieri, Maria Luisa
• Format: Article
• Language: English
• Subjects: Animals; Antioxidants - pharmacology; Betaine - analogs & derivatives; Betaine - metabolism; Cattle; Cell Death; Cell-Free System; Cells, Cultured; Endothelial cells; Endothelial Cells - physiology; Endothelium, Vascular - pathology; Ergothioneine; Ergothioneine - pharmacology; Ergothioneine sulfonic acid; Glucose - metabolism; Glutathione - metabolism; Histidine - analogs & derivatives; Histidine - metabolism; Hydrogen Peroxide - metabolism; Hyperglycaemia; Hyperglycemia - metabolism; Oligopeptides - metabolism; Ophthalmic acid; Oxidation-Reduction; Oxidative Stress; Sulfonic Acids - metabolism; Superoxide anion; Superoxides - metabolism; Tandem Mass Spectrometry
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2017.03.009

Ergothioneine (Egt), 2-mercapto-L-histidine betaine (ESH), is a dietary component acting as antioxidant and cytoprotectant. In vitro studies demonstrated that Egt, a powerful scavenger of hydroxyl radicals, superoxide anion, hypochlorous acid and peroxynitrite, protects vascular function against oxidative damages, thus preventing endothelial dysfunction. In order to delve the peculiar oxidative behavior of Egt, firstly identified in cell free-systems, experiments were designed to identify the Egt oxidation products when endothelial cells (EC) benefit of its protection against high-glucose (hGluc). HPLC-ESI-MS/MS analyses revealed a decrease in the intracellular GSH levels and an increase in the ophthalmic acid (OPH) levels during hGluc treatment. Interestingly, in the presence of Egt, the decrease of the GSH levels was lower than in cells treated with hGluc alone, and this effect was paralleled by lower OPH levels. Egt was also effective in reducing the cytotoxicity of H2O2 and paraquat (PQT), an inducer of superoxide anion production, showing a similar time-dependent pattern of GSH and OPH levels, although with peaks occurring at different times. Importantly, Egt oxidation generated not only hercynine (EH) but also the sulfonic acid derivative (ESO3H) whose amounts were dependent on the oxidative stress employed. Furthermore, cell-free experiments confirmed the formation of both EH and ESO3H when Egt was reacted with superoxide anion. In summary, these data, by identifying the EH and ESO3H formation in EC exposed to hGluc, highlight the cellular antioxidant properties of Egt, whose peculiar redox behavior makes it an attractive candidate for the prevention of oxidative stress-associated endothelial dysfunction during hyperglycemia. [Display omitted] •Egt reduces the high-glucose induced endothelial cell cytotoxicity.•Egt reduces the hydrogen peroxide and paraquat induced endothelial cell cytotoxicity.•Ophthalmic acid increases during Egt protection from oxidative stresses.•Glutathione decreases during Egt protection from oxidative stresses.•Egt reacts with superoxide anion generating mainly the Egt sulfonic acid derivative.