Forskning

May 29, 2019

Alkylpyrazines from coffee are extensively metabolized to pyrazine carboxylic acids in the human body

J I Kremer et al, 2019. Alkylpyrazines from coffee are extensively metabolized to pyrazine carboxylic acids in the human body, Mol Nutr Food Res, published online.

ABSTRACT:

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. We therefore conducted a human intervention study 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 µmol, 4.4 µmol, and 4.9 µmol, respectively. These alkylpyrazines were 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 was excreted as PA, as well as 26% as 5-OHPA, while 91% and 97% of the ingested 2,5-DMeP and 2,6-DMeP were 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.