title: Structural specificity of electric potentials in the coulometric-array analysis of catechins and theaflavins.
abstract: We have established a novel method to evaluate the redox properties of tea polyphenols by HPLC-coulometric-array analysis. We plotted the quantity of electricity (µC) on the vertical axis and the electric potential (mV), adjusted with the associated palladium reference electrode, on the horizontal axis to provide "quantity versus potential (QP) plot". The patterns of the plots correspond to the derivative of a hydrodynamic voltammogram or a current-voltage curve, with the electric potentials of the peaks in the QP plot corresponding to the half-wave potentials in the current-voltage curve. We confirmed that catechins and theaflavins are oxidized depending on the electric potentials of their partial structures, and found that all compounds showing a peak at 0 mV in the QP plots produce hydrogen peroxide (H2O2) during the autoxidation process.
authors.affiliation: Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
authors.forename: Kanako
authors.initials: K
authors.lastname: Matsuura
authors.affiliation: Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Usui
authors.affiliation: Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kan
authors.affiliation: Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ishii
authors.affiliation: Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan ; Department of Food Science and Technology, Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino-shi, Tokyo 180-8602, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nakayama
keywords: catechins; coulometric-array analysis; electric potentials; hydrogen peroxide; theaflavins