Urinary metabolite profiling identifies novel colonic metabolites and conjugates of phenolics in healthy volunteers

Authors

  • Rui C. Pimpão,

    1. Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, EAN, Oeiras, Portugal
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  • Tristan Dew,

    1. School of Food Science and Nutrition, University of Leeds, Leeds, UK
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    • Current address: Dr. Tristan Dew, Bradford School of Pharmacy, School of Life Sciences, University of Bradford, Bradford, BD7 1DP, United Kingdom

  • Maria E. Figueira,

    1. iMed-UL and Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, Lisboa, Portugal
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  • Gordon J. McDougall,

    1. The James Hutton Institute, Scotland, UK
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  • Derek Stewart,

    1. The James Hutton Institute, Scotland, UK
    2. Bioforsk – Norwegian Institute for Agricultural and Environmental Research, Tromso, Norway
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  • Ricardo B. Ferreira,

    1. Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, EAN, Oeiras, Portugal
    2. Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, Lisboa, Portugal
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  • Claudia N. Santos,

    1. Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, EAN, Oeiras, Portugal
    2. Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
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  • Gary Williamson

    Corresponding author
    1. School of Food Science and Nutrition, University of Leeds, Leeds, UK
    • Correspondence: Professor Gary Williamson, School of Food Science and Nutrition, University of Leeds, Leeds, LS2 9JT, UK

      E-mail: g.williamson@leeds.ac.uk

      Fax: +44-113-343-2982

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Abstract

Scope

The colonic metabolism of dietary flavonoids, phenolic acids and their phenolic metabolites is complex and many metabolites and conjugates have not yet been unambiguously identified in humans.

Methods and results

Urine samples from nine healthy human volunteers obtained after the ingestion of a puree of five (poly)phenol-rich berry fruits were analysed using LC-Orbitrap MS to provide a preliminary indication of possible metabolites based on exact mass. In most cases, the identity of compounds was confirmed using standards produced either chemically or enzymically followed by analysis using LC-triple quadrupole MS. Sulphated, glucuronidated and methylated forms of catechol, pyrogallol and protocatechuic acid mostly appeared in urine after 8 h, suggesting colonic metabolism. Gallic acid and (−)-epicatechin conjugates appeared mainly before 4 h, indicative of absorption from the small intestine. Conjugates of ferulic, caffeic, and vanillic acid appeared at intermediate times.

Conclusion

We have positively identified metabolites and conjugates, some novel, in the urine of healthy volunteers after intake of multiple phenolics from a mixed puree from berry fruits, with each being excreted at specific and signature times. Some of these compounds could potentially be used as biomarkers of fruit intake. The possible biological activities of these colonic metabolites require further assessment.

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