Reactive oxygen species inhibitory diagrams and their usability for the evaluation of antioxidant ability

Abstract

TThe reactive oxygen species (ROS) inhibitory diagrams on the abilities of biosubstances to eliminate hydroxyl, superoxide and alkoxyl radicals were introduced and the role of biosubstances against the oxidative stress was discussed using these diagrams. Hydroxyl radical causes the hydrogen abstraction with alkyl compounds and the one-electron oxidation reaction with phenol compounds, and reacts with substances encountered first after the radical is born in the system without any peculiarity. In superoxide radical elimination, the disproportionation reaction becomes important than ordinal radical reaction with stable molecules. The reaction characteristics of alkoxyl radical is slightly different from both hydroxyl and superoxide radicals, which indicates the reaction peculiarity caused by its bulky structure (RO•, R = C(CH3)2-C(+NH2Cl–)NH2). The ROS inhibitory diagrams, especially the oxygen radical absorbance capacity (ORAC)-1/ids50 diagram, apparently indicate that each biosubstance has favorable free radical to eliminate. These excellent biosubstances in foods and beverages work as exogenous antioxidants in the biosystems for superoxide, hydroxyl and lipid peroxide radicals, and also supplement the role of endogenous antioxidants, L-ascorbic acid and reduced glutathione. As the ROS inhibitory diagrams are based on the eliminating abilities of free radicals produced during oxygen stress, they should respond to the need to search excellent endogenous antioxidants, and be excellent presentations for healthy life.