The Effect of Sulfur-Containing Compounds on the Quinoid Process of Adrenaline Autoxidation; Potential Neuroprotectors

—The superoxide-generating reaction of adrenaline autoxidation in an alkaline medium, used in vitro to identify the antioxidant properties of various compounds, simulates the complex multistep process of quinoid oxidation of catecholamines (CA) in the body. Sulfur-containing cysteine (Cys) and reduced glutathione (GSH), as well as oxidized glutathione (GSSG), have been shown to inhibit this process. The studied substances considered as inhibitors of quinoid oxidation have been also evaluated as antioxidants. The IC 50 values for Cys and GSH were close to 7.5 μM. Inhibition by GSSG was weaker and represented approximately 50–70