Metabolites of dietary atractyligenin glucoside in coffee drinkers' urine

Arabica roast coffee contains a substantial amount of water soluble atractyligenin-2-O-beta-D-glucoside, which is ingested by consumption of coffee brew. Metabolomics data suggest this coffee compound is excreted as glu-curonides, but the structures of conjugates have not been elucidated so far. We collected coffee drinkers' urine and isolated four metabolites by MS-guided liquid chromatographic fractionation. The structures were investi-gated by nuclear magnetic resonance (NMR) and time-of-flight mass spectrometry (ToF-MS) and identified as atractyligenin-19-O-beta-D-glucuronide (M1), 2 beta-hydroxy-15-oxoatractylan-4 alpha-carboxy-19-O-beta-D-glucuronide (M2), and 2 beta-hydroxy-15-oxoatractylan-4 alpha-carboxylic acid-2-O-beta-D-glucuronide (M3). An unconjugated metabolite (M4) was confirmed as atractyligenin. We analyzed spot urines from n = 6 coffee drinking individuals and detected the metabolites M1, M2 and M4 in every sample, and M3 in four out of six samples, suggesting interindividual differences in metabolism.

Automated summary

Arabica roast coffee contains a compound called atractyligenin-2-O-beta-D-glucoside, which is water soluble and ingested when drinking coffee brew. Metabolomics data shows that this compound is excreted in the form of glu-curones, but the structure of these conjugates has not been determined until now. Through analysis of urine samples from coffee drinkers, four metabolites were isolated and identified using nuclear magnetic resonance (NMR) and time-of-flight mass spectrometry (ToF-MS). These metabolites were atractyligenin-19-O-beta-D-glucuronide (M1), 2 beta-hydroxy-15-oxoatractylan-4 alpha-carboxy-19-O-beta-D-glucuronide (M2), 2 beta-hydroxy-15-oxoatractylan-4 alpha-carboxylic acid-2-O-beta-D-glucuronide (M3), and atractyligenin (M4).