Comprehensive Evaluation of Antioxidant Activity for Various Teas Using Radar Charts

Abstract

Antioxidant activities of three polyphenol compounds, teas (green tea, oolong tea, and black tea), and five commercially available bottled teas have been evaluated, because comprehensive methods to evaluate antioxidant properies have not been established yet in spite of comsumers' stong concern for the antioxidant activities of teas. The antioxidant activities against hypochlorite radical and hydroxyl radical were successfully measured by a previously reported method based on myogobin structure change. The acitivities expressed by myogrobin protective ratio increased with the sample concentration under a constant radical concentration. The antioxidant activities of the samples were also measured by the widely used DPPH method. In order to characterize the properties of the samples comprehensively, the antioxidant activities against three different radicals were compared in a radar chart. All polyphenol compounds showed relatively high activities against all three radicals. All teas showed similar patterns as the polyphenol compounds in the radar charts. The strength of the activities, however, strongly depends on the samples. Thus, the antioxidant activities of various teas have been successfully evaluated in a comprehensive way using the radar charts.