Analysis of urinary metabolites of tea catechins by liquid chromatography/electrospray ionization mass spectrometry

C. Li, X. Meng, B. Winnik, M. J. Lee, H. Lu, S. Sheng, B. Buckley, C. S. Yang

Research output: Contribution to journalArticlepeer-review

106 Scopus citations

Abstract

Tea has been proposed to have beneficial health effects which have been attributed to the polyphenolic compounds known as catechins. The bioavailability and biotransformation of these compounds, however, are not clearly understood. In this study, we used liquid chromatography/electrospray ionization-mass spectrometry (LC/ESI-MS) to determine urinary glucuronidated and sulfated tea catechins and their metabolites (including methylated and ring-fission metabolites) based on the detection of deprotonated molecular ions and aglycone fragment ions. The compound resolution was achieved both chromatographically and mass spectroscopically. After green tea administration, the major conjugates appeared in human, mouse, and rat urine samples were identified as monoglucuronides and monosulfates of (-)-epigallocatechin (EGC) and (-)-epicatechin. We also found O-methyl-EGC-O-glucuronides and -O-sulfates and O-methyl-epicatechin-O-sulfates in human urine. (-)-5-(3′,4′,5′-Trihydroxyphenyl)-γ-valerolactone (M4) and (-)-5-(3′,4′-dihydroxyphenyl)-γ-valerolactone (M6), the ring-fission metabolites of EGC and (-)-epicatechin, respectively, were also predominantly in monoglucuronide and monosulfate forms in the urine. In comparison to rats, the urinary metabolite profiles of tea catechins in mice resemble more closely to those in humans. This is the first report describing direct simultaneous analysis of multiple tea catechin conjugates in urine samples. This method will allow more thorough investigations of the biotransformation of tea polyphenols.

Original languageEnglish (US)
Pages (from-to)702-707
Number of pages6
JournalChemical Research in Toxicology
Volume14
Issue number6
DOIs
StatePublished - 2001

All Science Journal Classification (ASJC) codes

  • Toxicology

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