Evaluation of Hydroxyl Radical-Scavenging Abilities of Silica Hydride, an Antioxidant Compound, by a Fe 2+ -EDTA-Induced 2-Hydroxyterephthalate Fluorometric Analysis

The hydroxyl radical scavenging capacity and efficacy of a novel organosiliceous anionic hydride compound, silica hydride, were quantified by a recently developed method. The method measures a direct relationship between the hydroxyl radical scavenging capability of the antioxidant compound and the linear decrease in signal from a fluorescent 2-hydroxyterephthalate product created by reacting an Fe(2+)-EDTA complex in the presence of a potential radical scavenger. A fluorescence signal half-inhibition, IC(50), value of 1.4 +/- 0.1 muM was obtained for silica hydride compounds. The validity of the analysis was verified by electron spin resonance spectroscopy, spectrophotometric analysis of NAD(+)/NADH ratios, mitochondrial membrane potential measurements, and assays of both cytochrome c (Fe(3+)) to cytochrome c (Fe(2+)) and epinephrine to adenochrome reductions.