The involvement of ethanol in the free radical reaction of 6-hydroxydopamine

ESR spin trapping technique was used to detect and analyze free radical formation. When 6-hydroxydomine (6-OHDA) was incubated alone or in the presence of a free radical generating system (H₂O₂ and FeSO₄), hydroxyl free radicals were observed in a concentration-dependent manner. Glutathione was found to be the most effective scavenger of the ESR signal when compared with vitamin E or Mannitol. The addition of ethanol resulted in the formation of the pure hydroxyethyl free radicals. The amount of hydroxyethyl free radicals in the system was dependent upon the concentration of ethanol and the formation of hydroxyethyl free radicals correlated well with the extent of lipid peroxidation and the loss of enzymic activity of the membrane-bound (Na⁺, K⁺)-ATPase. We suggest that in the biological system ethanol may potentiate the neurotoxicity of 6-OHDA with the formation of hydroxyethyl free radicals, which are longer-lived and far more damaging to membranes that the hydroxyl radicals. These data lead us to further hypothesize that the neuronal degeneration caused by 6-OHDA and other compounds that generate free radicals could be potentiated in the presence of ethanol.