Targeted analysis of microbial-generated phenolic acid metabolites derived from grape flavanols by gas chromatography-triple quadrupole mass spectrometry

Abstract

Grape-derived products contain a wide array of bioactive phenolic compounds which are of significant interest to consumers and researchers for their multiple health benefits. The majority of bioavailable grape polyphenols, including the most abundant flavan-3-ols, i.e. (+)-catechin and (-)-epicatechin, undergo extensive microbial metabolism in the gut, forming metabolites that can be highly bioavailable and bioactive. To gain a better understanding in microbial metabolism of grape polyphenols and to identify bioactive metabolites, advanced analytical methods are needed to accurately quantitate microbial-derived metabolites, particularly at trace levels, in addition to their precursors. This work describes the development and validation of a high-throughput, sensitive and reproducible GC-QqQ/MS method operated under MRM mode that allowed the identification and quantification of 16 phenolic acid metabolites, along with (+)-catechin and (-)-epicatechin, in flavanol-enriched broth samples anaerobically fermented with human intestinal bacteria. Excellent sensitivity was achieved with low limits of detection and low limits of quantification in the range of 0.24-6.18 ng/mL and 0.480-12.37 ng/mL, respectively. With the exception of hippuric acid, recoveries of most analytes were greater than 85%. The percent accuracies for almost all analytes were within ±23% and precision results were all below 18%. Application of the developed method to in vitro samples fermented with different human gut microbiota revealed distinct variations in the extent of flavanol catabolism, as well as production of bioactive phenolic acid metabolites. These results support that intestinal microbiota have a significant impact on the production of flavanol metabolites. The successful application of the established method demonstrates its applicability and robustness for analysis of grape flavanols and their microbial metabolites in biological samples.

Flavonoids as an Intervention for Alzheimer’s Disease: Progress and Hurdles Towards Defining a Mechanism of Action1

“…Furthermore, there are important inter-individual differences in the composition of the gut microbiome as a result of various factors including age, sex, drug use and dietary intake [ 228 ]. This is significant as the composition of the human gut microbiome has so far been shown to alter the metabolism of flavonols [ 229, 230 ] and isoflavones [ 215 ]. Therefore, it may become beneficial to assess the microbiome of an individual before recommending flavonoid interventions in order to personalise the amount and type of flavonoids for maximum efficacy.…”

Metabolomics Technologies for the Identification and Quantification of Dietary Phenolic Compound Metabolites: An Overview

“…The application of GC to determine PCM is not limited to its coupling with MS. GC-QqQ/MS was applied by Carry et al to analyze microbial phenolic acid metabolites of grape epicatechin and catechin [128]. Furthermore, Kay et al, employed GC with a flame ionization detector to identify the glycosylating structures of cyanidin, and the derivatization of sugars was performed with TMSI + pyridine [54].…”

Changes in the Serum Metabolome of Patients Treated With Broad-Spectrum Antibiotics

“…On the other hand mixed fecal cultures or certain constituents of the human GMB can, under anaerobic conditions, generate BA or its hydroxylated metabolites from a variety of precursors, including free L-tyrosine or L-phenylalanine [80,81], 4-hydroxyphenylpyruvic acid [81], polyphenol rich dietary components (eg, berries, black tea, bran, fruit juices, wine) [82][83][84][85][86][87][88][89], or pure polyphenols themselves (eg, catechin, epicatechin, proanthocyanidins, quercetin) [90][91][92][93].…”