Structural specificity of electric potentials in the coulometric-array analysis of catechins and theaflavins

• Published in: Journal of Clinical Biochemistry and Nutrition Vol. 55; no. 2; pp. 103 - 109
• Main Authors: Matsuura, Kanako, Usui, Yumiko, Kan, Toshiyuki, Ishii, Takeshi, Nakayama, Tsutomu
• Format: Journal Article
• Language: English
• Published: Japan SOCIETY FOR FREE RADICAL RESEARCH JAPAN 2014; Japan Science and Technology Agency; the Society for Free Radical Research Japan
• Subjects: catechins; coulometric-array analysis; electric potentials; hydrogen peroxide; Original; theaflavins; catechins; electric potentials; coulometric-array analysis; theaflavins; hydrogen peroxide
• ISSN: 0912-0009; 1880-5086
• DOI: 10.3164/jcbn.13-101

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.