Dose-dependency of multiple free radical-scavenging activity of edaravone.

BACKGROUND:Edaravone is a powerful free radical scavenger that is in clinical use. However, data concerning its dose-response relationship against multiple free radicals remain sparse. The purpose of the present study was to demonstrate the dose-dependency of direct scavenging activity of edaravone against multiple free radical species. MATERIALS AND METHODS:Free radical-scavenging activities of edaravone against six free radical species were evaluated by electron spin resonance spectroscopy using spin-trapping method. RESULTS:Edaravone scavenged the following free radicals in dose-dependent manners with reaction rate constants (kedaravone) or 50% inhibitory concentration (IC50) as indicated: hydroxyl radical (kedaravone = 5.2 × 1010 M-1 s-1), superoxide anion (kedaravone/kG-CYPMPO = 0.63), tert-butyl peroxyl radical (kedaravone/kG-CYPMPO = 8.8), ascorbyl free radical (IC50 = 0.17 ± 0.06 mM), 2,2-diphenyl-1-picrylhydrazyl (DPPH, IC50 = 4.7 ± 0.3 μM), and nitric oxide (kedaravone = 7.0 × 103 M-1 s-1). CONCLUSIONS:The dose-dependent scavenging activities of edaravone against multiple free radical species were clearly illustrated. It is speculated that edaravone acts as antioxidant by dose-dependently scavenging multiple free radical species along the chain reactions of oxidative stress in surgery.