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Analysis of tea catechins in human plasma by high-performance liquid chromatography with solid-phase extraction.

Unno T, Sagesaka YM, Kakuda T

Central Research Institute, ITO EN, Ltd., 21 Mekami, Makinohara-shi, Shizuoka 421-0516, Japan. t-unno@itoen.co.jp

Accurate monitoring of tea catechins in biological samples might provide a means of better evaluation of their benefits. The aim of the present study was to develop a rapid method for extracting tea catechins from human plasma samples with a solid-phase extraction technique and to subsequently measure their concentrations using an HPLC system. A human plasma sample spiked with known concentrations of the analyte standards was passed through a Waters Oasis HLB cartridge. After repeated washing, tea catechins were eluted with 70% dimethylformamide containing 0.1% phosphoric acid, and the resulting eluate was injected into an HPLC system. Analytes were separated on a reverse-phase C18 column using an isocratic mobile phase and detected electrochemically. The coefficient of variation for inter- and intraday reproducibility was less than 5.0% and 6.4%, respectively. Linearity was established for the concentration range of 0.01-1.0 microM. The method was successfully applied to measure tea catechin concentrations in the plasma of two healthy subjects who received a single ingestion of a green tea beverage. The proposed method enables the rapid and accurate quantitation of plasma tea catechins and might prove useful for the evaluation of beneficial health effects of tea consumption.

Published 21 December 2005 in J Agric Food Chem, 53(26): 9885-9.
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