Antioxidative activity of a novel antioxidant resorcimoline

During the synthesis of a known drug, we synthesized a novel compound impromptu, which we have named resorcimoline. This compound exhibited significant antioxidative activity. In this report, we present the concentration-dependent free radical scavenging activity of resorcimoline against various free radical species. The scavenging activity of resorcimoline was evaluated against nine free radicals using electron spin resonance spectroscopy with a spin-trapping method. These free radicals were hydroxyl radical, superoxide anion, <i>tert</i>-butyl peroxyl radical, <i>tert</i>-butoxyl radical, ascorbyl free radical, singlet oxygen, nitric oxide, 2,2-diphenyl-1-picrylhydrazyl, and tyrosyl radical. Sigmoid concentration-response curves were fitted to estimate the reaction rate constants of resorcimoline for the free radicals, and these were compared with those of edaravone, the only current clinically approved free radical scavenger. The antioxidative activity of resorcimoline against lipid peroxidation within tissue was assessed using the thiobarbituric acid reactive substance (TBARS) assay. The cytotoxicity and stability of resorcimoline were also evaluated. Resorcimoline demonstrated significant concentration-dependent scavenging activity against all tested free radicals. Notably, the reaction rate constants for superoxide anion and nitric oxide were significantly higher than those of edaravone, while the rate constant for hydroxyl radical was significantly lower. The TBARS assay revealed that resorcimoline inhibited tissue lipid peroxidation in a concentration-dependent manner. Moreover, resorcimoline exhibited no cytotoxicity at concentrations up to 100 μM and remained stable at room temperature under ambient light for 7 d. These findings indicate that resorcimoline's direct free radical scavenging activity could contribute to its potential clinical antioxidative effects.