Human urinary metabolite profile of tea polyphenols analyzed by liquid chromatography/electrospray ionization tandem...

Tea is rich in polyphenols and has a variety of biological activities. In order to better understand the biological effects of tea constituents on human health, markers for their exposure and their metabolic fates are needed. Previously, we have characterized several catechin metabolites in the blood and urine, but more information on the metabolite profile of tea polyphenols is needed. In the present study, the human urinary metabolite profile of tea polyphenols was investigated using liquid chromatography/electrospray ionization tandem mass spectrometry with data-dependent acquisition. With data-dependent MS/MS analysis by collecting the MS2 and MS3 spectra of the most intense ions in the sample, we identified more than twenty metabolites of tea polyphenols from human urine samples. (-)-Epigallocatechin (EGC) glucuronide, methylated EGC glucuronide, methylated EGC sulfate, (-)-epicatechin (EC) glucruronide, EC sulfate, methylated EC sulfate, as well as the glucuronide and sulfate metabolites of the ring-fission metabolites of tea catechins, 5-(3',4',5'-trihydroxyphenyl)-gamma-valerolactone (M4), 5-(3',4'-dihydroxyphenyl)-gamma-valerolactone (M6) and 5-(3',5'-dihydroxyphenyl)-gamma-valerolactone (M6'), were the major human urinary metabolites of tea polyphenols. To our knowledge, this is the first report of the direct simultaneous analysis of the human urinary metabolite profile of tea polyphenols using single sample analysis. This method can also be used for thorough investigations of the metabolite profiles of many other dietary constituents.