Simultaneous determination of the pharmacokinetics of A-type EGCG and ECG dimers in mice plasma and its metabolites by UPLC-QTOF-MS

A-type epigallocatechin-3-gallate (EGCG) and epicatechin-3-O-gallate (ECG) dimers have multiply biological activities. In this study, the pharmacokinetics of them were investigated in mice after a single dose intravenous administration, and the metabolites in mice plasma and urine were investigated by ultra-performance liquid chromatography-Quadrupole-time of flight mass spectrometer (UPLC-QTOF-MS). Our results showed that the half-life (t1/2) of A-type EGCG and ECG dimers were 116.37 min and 33.04 min, respectively, and the maximal concentration in plasma was 32.81 μg/mL and 55.59 μg/mL, respectively. It was found that two dimers were firstly experienced by quinone methide (QM) fission to form the EGCG and ECG analogue, and the phase II metabolites were generated subsequently. The main metabolites in plasma and urine were glucuronidation and sulphation derivatives. In addition, small molecule weight of phenolic acids were detected in urine.