2.1 Reactivity between Electro-generated O2 •-and Pyrazine Antiviral Drugs 2.1.1 Cyclic Voltammograms (CV) of O2/O2 • in the presence of Pyrazine Antiviral Drug Based on electrochemical measurements in N, N-dimethylformamide (DMF), the reactivity between pyrazine antiviral drugs and O2 •-was discussed (Supporting Information, Figure ). were reported in our previous paper, and are presented here for comparison to show the CV behavior demonstrating an ET between O2 •-and substrate. In aprotic and unbuffered solvents such as DMF, O2 shows quasi-reversible redox at -1.284 V vs ferrocenium ion/ferrocene (Fc + /Fc) couple (Equation (1)), resulting in the formation of O2 •-in the initial cathodic scan and reoxidation to O2 in the returned anodic scan (solid lines, Figure ). The reversible CVs investigated here were all modified to irreversible CVs with a loss of anodic current by the presence of the protic compounds (a-d) in a concentration-dependent manner, suggesting that the initial homogeneous reaction between electro-generated O2 •-and the compounds are PT. This result is supported by the fact that the CV traces in the absence of O2 (removed by bubbled dinitrogen (N2)) show no peaks over the potential range investigated (data not shown). Thus, the loss of reversibility in the O2/O2 •-is due to the PT from the compounds forming HO2 • (Equation ( )).