Alkylpyrazines from Coffee are Extensively Metabolized to Pyrazine Carboxylic Acids in the Human Body

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. 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.

Coffee Roasting and Extraction as a Factor in Cold Brew Coffee Quality

“…2-methylpyrazine was the most abundant compound among the pyrazines group in the experiment. This is in agreement with the results of Kremer et al [31], who reported a range of concentration of the aromatic compound in coffee from 34.8 ppm to 91.6 ppm. The mean value in our study was 47.9 ppm, the overall range was between 1.0 and 121.5 ppm (µg/g).…”

A Review of Coffee By-Products Including Leaf, Flower, Cherry, Husk, Silver Skin, and Spent Grounds as Novel Foods within the European Union

“…It can therefore be deduced that the rest remains in spent coffee grounds. In humans, alkyl pyrazines are metabolized to their corresponding carboxylic acids and almost completely excreted renally [139]. Spent coffee grounds are susceptible to contamination with mycotoxins, therefore Iriondo-DeHond et al investigated this.…”

Urine Metabolome Profiling Reveals Imprints of Food Heating Processes after Dietary Intervention with Differently Cooked Potatoes

“…Pyrazine analogues are also present in a variety of other heat-treated foods, , such as in coffee where 2-methylpyrazine and 2,5-dimethylpyrazine are present as important aroma compounds; the difference compared with M12-M14 is the different types of aminoketones for hererocyclization, so the pyrazine-derived compounds may or may not be specific for intake of deep-fried potatoes; however, this has to be further investigated.…”