Identification of phenolic metabolites in human urine after the intake of a functional food made from grape extract by a high resolution LTQ-Orbitrap-MS approach

Grape pomace (GP) is known to be a rich source of polyphenols with biological activity which may be used as functional ingredients for the development of new health-promoting products. Numerous studies have reported that bioactive compounds may act through multiple mechanisms. In order to verify the oral absorption and metabolism of grape polyphenols, we performed a prospective, randomised and cross-over acute study in 12 volunteers with two interventions: 500 mL of a functional beverage enriched with 200 mL of GP and 500 mL of a control beverage without GP. In this work, liquid chromatography coupled with an electrospray ionization hybrid linear ion trap quadrupole-Orbitrap-mass spectrometry (LC/ESI-LTQ-Orbitrap-MS) technique has been used to accurately identify phenolics in GP and human urine. In GP, 41 phenolic compounds were identified mainly procyanidins, phenolic acids and flavonols, and in human urine over 70 metabolites of phenolic compounds including microbiota metabolites, glucuronides and sulfate derivatives were detected. Overall, high resolution mass spectrometry (HR-MS) enhances the identification of a large variety of polyphenols and their metabolites with great mass accuracies for all molecular ions.