Long-term decomposition of aqueous S-nitrosoglutathione and S-nitroso-N-acetylcysteine: Influence of concentration, temperature, pH and light

Publication date: Available online 7 January 2019Source: Nitric OxideAuthor(s): Gabriela Freitas P. de Souza, Jaqueline Priscilla Denadai, Guilherme F. Picheth, Marcelo Ganzarolli de OliveiraAbstractPrimary S-nitrosothiols (RSNOs) have received significant attention for their ability to modulate NO signaling in many physiological and pathophysiological processes. Such actions and their potential pharmaceutical uses demand a better knowledge of their stability in aqueous solutions. Herein, we investigated the effects of concentration, temperature, pH, room light and metal ions on the long-term kinetic behavior of two representatives primary RSNOs, S-nitrosoglutathione (GSNO) and S-nitroso-N-acetylcysteine (SNAC). The thermal decomposition of GSNO and SNAC were shown to be affected by the auto-catalytic action of the thiyl radicals. At 25 °C in the dark and protected from the catalytic action of metal ions, GSNO and SNAC solutions 1 mM showed half-lives of 49 and 76 days, and apparent activation energies of 84 ± 14 and 90 ± 6 kJ mol−1, respectively. Both GSNO and SNAC exhibited increased stability in the pH range 5–7. At high pH the decomposition pathway of GSNO involves the formation of an intermediate (GS-NO22-), which decomposes generating GSH and nitrite. GSNO solutions displayed lower sensitivity to the catalytic action of metal ions than SNAC and the exposure to room light led to a 5-fold increase in the initial rates of decomposition of both RSNOs....

Source: Nitric Oxide - January 8, 2019 Category: Chemistry Source Type: research