Evaluation of Multiple Antioxidant Activities in Food Components
Nippon Shokuhin Kagaku Kogaku kaishi
In recent years, studies of the antioxidant capacity of foods has been actively pursued, with the antioxidant activity of various food components being reported. Many methods have been developed to evaluate antioxidant activity, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, superoxide dismutase (SOD) activity, and oxygen radical absorbance activity (ORAC). The DPPH radical-scavenging method measures radical removal, producing a characteristic change to
... nge to colorlessness in the assay upon conversion to the DPPH radical, which is a stable organic radical. SOD is an enzyme that was discovered by McCord and Fridovich, and is a superoxide radical (O • ) scavenger that is component of the endogenous antioxidant system. SOD catalyzes the conversion of superoxide to either hydrogen peroxide (H 2 O 2 ) or oxygen (O 2 ), and is used to measure antioxidant ingredients exhibiting SOD-like activity. Implementation is simple and easy, and these methods are widely used for the evaluation of antioxidant activity. The ORAC method was developed in 1992 by Cao et al. at the U.S. National Institute of Aging. The assay uses fluorescein as a fluorescent probe to measure antioxidant activity in the presence of underlying reactive oxygen generation. The fluorescent intensity of fluorescein degrades over time in the presence of reactive oxygen, which is used to measure antioxidant activity as an index. Because the ORAC assay relies on generated peroxy radicals, the classification of fixed quantities of hydrophilic and lipophilic antioxidant materials is possible and is correlated with in vivo effects. Additional merits of the ORAC assay include the ability to assess antioxidant activity using a chemical reaction that is relatively simple, easily operated, and does not require specialized apparatus. However, the presence of compounds with antioxidant activity greatly influences the ORAC assay, and a potential drawback of the assay is that its results may not reflect antioxidant activity in vivo. In this study, chemical analyses(DPPH radical removal activity, SOD assay copper ion reduction)and the cellular antioxidant stress response, measured using a luciferase reporter assay of antioxidant response element induction through the Keap-1/Nrf2 pathway, was used to more accurately reflect in vivo conditions in evaluating antioxidant activity. The possibility that food components exhibit various antioxidant activities was evaluated using multiple assay systems.