Probucol scavenged 1,1-diphenyl-2-picrylhydrazyl radicals and inhibited formation of thiobarbituric acid reactive substances.

Probucol is suggested to have antioxidant properties. The direct scavenging action of probucol on hydroxyl radicals, superoxide and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals were examined using electron spin resonance (ESR) spectrometry. Probucol scavenged DPPH radicals dose dependently but showed no effect on hydroxyl radicals and superoxide generated by Fenton reaction and by hypoxanthine-xanthine oxidase system, respectively. It inhibited the formation of thiobarbituric acid reactive substances (TBARS) in rat cortex homogenate induced by ascorbic acid and FeCl2 at low dose, but it increased TBARS formation at high doses. Probucol showed no effect on the carbon centered radicals. Iron injection into the rat cortex, which is an experimental model for traumatic epilepsy, increased TBARS level in the cortex, hippocampus, striatum and cerebellum, but pretreatment with probucol inhibited the increase in these brain parts except for the hippocampus. These results suggest that the antioxidant property of probucol is partly due to its free radical scavenging effect.