Antioxidant properties and hypothetic radical mechanism of fullerenol C60(OH)24

Abstract

The antioxidant properties of open cage water-soluble fullerenol C 60 (OH) 24 were tested by measuring their ability to scavenge stable 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and reactive hydroxyl radical ( • OH) during the Fenton reaction using electron spin resonance (ESR) spectroscopy. The fullerenol, obtained by newly developed method in our laboratory, scavenged both types of investigated radicals in dose-dependent manner in concentration range of 0.18-0.88 mmol/l. Generally, higher concentrations (0.71-0.88 mmol/l) of fullerenol possessed better inhibition of hydroxyl radical (50-82%) than of DPPH radical (28-50%). Fullerenol can exhibit its antioxidative properties by simultaneous hydrogen atom donation to investigated free radicals (DPPH and • OH). This reaction also gave rise to the generation of the fullerenol radical C 60 (OH) 23 which presence was confirmed by ESR. The interaction between hydroxyl radical and fullerenol is also based on radical-addition reaction of 2n • OH radicals to remaining olefinic double bonds of fullerenol core to yield C 60 (OH) 24 + 2n • OH (n = 1-12).