Structural Transformation of 8-5-Coupled Dehydrodiferulates by Human Intestinal Microbiota.
Ingested dehydrodiferulates (DFAs) are partially released from cereal dietary fiber by human colonic microbiota, but little research has explored the further microbial metabolism of 8-5-coupled DFAs. This study investigated the in vitro microbial metabolism and elucidated major metabolites of free 8-5-DFAs (benzofuran and open forms) and an esterified analogue, 8-5-DFA diethyl ester (benzofuran). Synthesized standard compounds were incubated with fresh human fecal suspensions. Metabolites were isolated and structurally elucidated using high-resolution-LC-time-of-flight-(ToF)-MS, GC-MS, and NMR. Nine metabolite structures were unambiguously characterized with NMR, and four additional metabolites were tentatively identified to reveal structural conversion motifs: propenyl side chain hydrogenation (all substrates), O-demethylation and reductive ring-opening (8-5-DFA diethyl ester and free 8-5-DFA [benzofuran]), and de-esterification (8-5-DFA diethyl ester). A pathway of microbial 8-5-DFA metabolism was proposed based on metabolite formation kinetics. Importantly, de-esterification of the 8-5-DFA diethyl ester occurred primarily after and/or concurrently with other metabolism steps. Cleavage to monomers was not observed.
Department of Food Chemistry and Phytochemistry, Karlsruhe Institute of Technology (KIT) , Adenauerring 20a, 76131 Karlsruhe, Germany.
Rachel R
RR
Schendel
Department of Food Chemistry and Phytochemistry, Karlsruhe Institute of Technology (KIT) , Adenauerring 20a, 76131 Karlsruhe, Germany.
Cecile
C
Karrer
Department of Safety and Quality of Fruit and Vegetables, Federal Research Institute of Nutrition and Food, Max Rubner-Institute (MRI) , Haid-und-Neu-Straße 9, 76131 Karlsruhe, Germany.
Diana
D
Bunzel
Department of Safety and Quality of Fruit and Vegetables, Federal Research Institute of Nutrition and Food, Max Rubner-Institute (MRI) , Haid-und-Neu-Straße 9, 76131 Karlsruhe, Germany.
Melanie
M
Huch
Department of Food Chemistry and Phytochemistry, Karlsruhe Institute of Technology (KIT) , Adenauerring 20a, 76131 Karlsruhe, Germany.
Andreas A
AA
Hildebrand
Department of Safety and Quality of Fruit and Vegetables, Federal Research Institute of Nutrition and Food, Max Rubner-Institute (MRI) , Haid-und-Neu-Straße 9, 76131 Karlsruhe, Germany.
Sabine E
SE
Kulling
Department of Food Chemistry and Phytochemistry, Karlsruhe Institute of Technology (KIT) , Adenauerring 20a, 76131 Karlsruhe, Germany.
Mirko
M
Bunzel
D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001711:Biotransformation; D003373:Coumaric Acids / Q000737:chemistry* / Q000378:metabolism*; D000069196:Gastrointestinal Microbiome; D041981:Gastrointestinal Tract / Q000737:chemistry / Q000382:microbiology; D006801:Humans; D007700:Kinetics; D015394:Molecular Structure
D003373:Coumaric Acids; C516502:diferulic acid
8−5-dehydrodiferulic acid; diferulic acids; ferulic acid; human intestinal microbiota; microbial metabolism