Table 6.

Mechanisms of action of edaravone and various antioxidants

Antioxidant	Scavenging activities against free radicals and peroxynitrite	Mechanism of antioxidant effects
Disufenton	– reacts with hydroxyl radicals and alcohol- and/or ether-derived radicals to form adducts.	– possesses low BBB permeability, does not migrate into the cell, and eliminates radical species derived from vascular endothelium extracellularly.
Ebselen	– reacts with superoxide anion radical and peroxynitrile, but not with peroxyl radicals or other similar radicals.	– reduces radical precursors by reducing lipid peroxides to the corresponding alcohols by glutathione peroxidase-like action in collaboration with thiols in vivo.
Nicaraven	– eliminates hydroxyl radicals and the like by donating a hydrogen atom from the amide structure.	– based on its molecular structure and lipophilicity, it is presumed that its brain permeability is not high, but details are unknown.
Tirilazad	– weakly reactive with radicals	– migrates to the cell membrane of the vascular endothelium, decreases the interaction between lipid molecules by reducing the membrane fluidity of cells, and suppresses the propagation of lipid peroxidation by radical chain reaction.
		– suppresses membrane peroxidation by a synergistic effect with vitamin E in the membrane.
Edaravone	– scavenges broad range of radical species and peroxynitrite, but does not react with superoxide anion radicals or hydroperoxides.	– readily enters biological membrane and distribute both plasma and tissue.
	– its anionic form has high radical scavenging activity.	– suppresses peroxidation by synergistic effects with α-tocopherol and ascorbic acid in the membrane.