Evaluation of the Antioxidant Abilities of Water- Soluble Biosubstances Using the ORAC-ESR Assay in Combination with the Hydroxyl and Superoxide Radical-Eliminating Abilities

摘要

The oxygen radical absorbance capacity (ORAC) values of various watersoluble biosubstances using the ORAC-electron spin resonance (ESR) assay were examined, and an advanced database of water-soluble biosubstances in combination with the hydroxyl and the superoxide radical-eliminating abilities was prepared. The ORAC-ESR assay is based on the competitive reaction between the spin trapping of the 2,20-azobis(2-amidinopropane) dihydrochloride (AAPH)-derived alkoxyl radical and its elimination by substrate. The alkoxyl radical-eliminating ability of substrate was calculated from the decrease in the ESR signal of the 5-(2,2-dimethyl-1,3-propoxy cyclophosphoryl)-5-methyl-1-pyrroline N-oxide (CYPMPO) spin adduct of the alkoxyl radical. The determination of ORAC values was performed by determining the specificity of a spin trap relative to a standard radical eliminator, 6-hydroxy-2,5,7,8- tetramethylchroman-2-carboxylic acid (Trolox). The ORAC values [lmol Trolox equivalent (TE)/g] of water-soluble biosubstances were classified into three groups, the high value group (over 10,000 lmol TE/g), the intermediate value group (400- 10,000 lmol TE/g), and the low value group (＜100 lmol TE/g). The two-dimensional diagrams for the ORAC values (lmol TE/g) and the hydroxyl and superoxide radical-eliminating abilities (1/[id~h_(50)(mg/ml)] and 1/[ids 50(mg/ml)], respectively) were depicted. Biosubstances having higher ORAC values had higher superoxide radicaleliminating abilities (the correlation factor 0.73). Little correlation between theORAC values and the 1/[id~h_(50)(mg/ml)] values (the correlation factor 0.32) was observed. The obtained diagrams should provide a database for the study of the antioxidant abilities of foods and pharmaceutics.