Free radical scavenging by bifemelane hydrochloride and its major metabolites.

The scavenging effects of bifemelane hydrochloride and of its two major metabolites (M-1 and M-2) on the 1,1-diphenyl-2-picryl hydrazyl radical, the superoxide anion radical and the hydroxyl radical, were examined using electron spin resonance spectrometry in vitro. Bifemelane, though almost without any effect on the 1,1-diphenyl-2-picryl hydrazyl and superoxide anion radicals, scavenged dose-dependently the hydroxyl radical generated by FeSO4, H2O2 and diethylenetriaminepentaacetic acid. Both M-1 and M-2 scavenged dose-dependently the 1,1-diphenyl-2-picryl hydrazyl radical and the superoxide anion radical. M-1 also scavenged the hydroxyl radical as did bifemelane hydrochloride. These results suggest that the experimental and clinical effectiveness of bifemelane hydrochloride in cerebrovascular disease, aging and senile dementia may be due, at least partly, to its scavenging action and/or that of its metabolites on free radicals.