Release of Small Phenolic Metabolites from Isotopically Labeled ¹³C Lignin in the Pig Cecum Model

Abstract

A diet with a high dietary fiber content is often recommended in today's nutrition due to several beneficial health effects related to its intake. Lignin as a part of dietary fiber is the second most abundant natural polymer and considered to be stable during digestion. However, some studies indicate a partial degradation during the intestinal metabolism. To further elucidate this hypothesis, the aim of this study was to investigate whether lignin is metabolized by the gut microbiota using the ex vivo pig cecum model. As potential lignin-derived metabolites might already naturally occur in the pig cecal matrix, an approach using isotopically labeled 13 C lignin was chosen for this study. Ten small phenolic lignin degradation products and their time-dependent metabolism were identified via an untargeted HPLC-HRMS approach, and the quantity of the metabolites was estimated. From the results, we conclude that lignin is partially degraded releasing small phenolic metabolites.

Intestinal Metabolism of Selected Steroidal Glycoalkaloids in the Pig Cecum Model

“…The incubations of steroidal glycoalkaloids in ACS and DCS were performed for incubation periods from 0 to 24 h (0, 15, 30, 60, 120, 240, 480, 1200, and 1440 min). The bacterial activity of each cecum was tested by incubation of quercetin and fluorescein diacetate in ACS as indicators for metabolically active microbiota. , Incubation of the analytes in DCS was used as a control to exclude matrix effects and chemical degradation of the compounds. For incubation experiments, the 1 mM stock solutions were diluted in methanol to obtain 10 μM incubation solutions.…”

“…Tomatine, which is connected to a lycotetraose, was also included in the study to gain more data about the relevance of the glycosidic bond configuration for intestinal degradation. The pig cecum model is a powerful tool to elucidate the human intestinal metabolism, as specifically the microbiota in the gastrointestinal tract of humans and pigs is comparable, which was demonstrated by the characterization of the cecal microbiota using fluorescence in situ hybridization with 16S rRNA-based oligonucleotide probes and terminal-restriction fragment length polymorphisms of human and porcine stool samples. , It was successfully applied in several previous studies which investigated the intestinal metabolism of polyphenols − modified mycotoxins, imidazole alkaloids or lignin . Obtained results should provide further information on the metabolism of selected SGA and reduce uncertainties on the risk assessment.…”

Calcium Carbide: From Elemental Carbon to Isotope‐Economic Synthesis of 13C2‐Labeled Heterocycles†

“…[10][11][12][13] An introducing of stable isotope labeled compounds in biological objects allows detailled studies of metabolic processes in living organisms, including studies of drugs pharmacokinetic profile. [14][15][16][17][18][19][20][21] Isotopes of organogenic elements are widely used as labels, among them carbon-13 seems to be the most versatile and promising, since it allows to introduce labels directly into the skeleton of organic molecules. In past decades, C 2 -labeled terminal acetylenes.…”

“…[ 10‐13 ] An introducing of stable isotope labeled compounds in biological objects allows detailled studies of metabolic processes in living organisms, including studies of drugs pharmacokinetic profile. [ 14‐21 ]…”

“…Isotopes of organogenic elements are widely used as labels, [ 1‐26 ] among them carbon‐13 seems to be the most versatile and promising, since it allows to introduce labels directly into the skeleton of organic molecules. In past decades, 13 C‐labels have been extensively used in metabolic processes studies using mass spectrometry and NMR spectroscopy methods.…”