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Alkylpyrazines from Coffee are Extensively Metabolized to Pyrazine Carboxylic Acids in the Human Body
Author(s) -
Kremer Jonathan I.,
Pickard Stephanie,
Stadlmair Lara F.,
GlaßTheis Anika,
Buckel Leon,
Bakuradze Tamara,
Eisenbrand Gerhard,
Richling Elke
Publication year - 2019
Publication title -
molecular nutrition and food research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.495
H-Index - 131
eISSN - 1613-4133
pISSN - 1613-4125
DOI - 10.1002/mnfr.201801341
Subject(s) - carboxylic acid , chemistry , urine , pyrazine , ingestion , excretion , metabolism , food science , biochemistry , organic chemistry
Scope Coffee is a complex mixture of over 1000 compounds, including diverse heteroaromatic compounds such as alkylpyrazines. Little is known about the intake, metabolism, and bodily distribution of these compounds. Therefore, a human intervention study is conducted to investigate the excretion of alkylpyrazine metabolites in urine after the ingestion of brewed coffee containing alkylpyrazines. Methods and results After consuming a diet without heat‐processed food, ten volunteers consumed 500 mL of freshly brewed coffee prepared from coffee pads, providing intakes of 2‐methylpyrazine (2‐MeP), 2,5‐dimethylpyrazine (2,5‐DMeP), and 2,6‐dimethylpyrazine (2,6‐DMeP) amounting to 17.2, 4.4, and 4.9 µmol, respectively. These alkylpyrazines are metabolized into the corresponding pyrazine carboxylic acids, namely pyrazine‐2‐carboxylic acid (PA), 5‐hydroxypyrazine‐2‐carboxylic acid (5‐OHPA), 5‐methylpyrazine‐2‐carboxylic acid (5‐MePA), and 6‐methylpyrazine‐2‐carboxylic acid (6‐MePA). In total, 64% of the ingested 2‐MeP is excreted as PA, as well as 26% as 5‐OHPA, while 91% and 97% of the ingested 2,5‐DMeP and 2,6‐DMeP are recovered as 5‐MePA and 6‐MePA, respectively, in urine samples collected after coffee consumption. Conclusion This study provides evidence that alkylpyrazines are rapidly metabolized into the corresponding carboxylic acids and excreted via urine by humans, which is consistent with earlier rodent studies.