Quantification of Phenolic Acid Metabolites in Humans by LC–MS: A Structural and Targeted Metabolomics Approach

Abstract

Aim: Co-metabolism between a human host and the gastrointestinal microbiota generates many small phenolic molecules such as 3-hydroxy-3-(3-hydroxyphenyl)propanoic acid (3,3-HPHPA), which are reported to be elevated in schizophrenia and autism. Characterization of these chemicals, however, has been limited by analytic challenges. Methodology/results: We applied HPLC to separate and quantify over 50 analytes, including multiple structural isomers of 3,3-HPHPA in human cerebrospinal fluid, serum and urine. Confirmation of identity was provided by NMR, by MS and other detection methods. The highly selective methods support rapid quantification of multiple metabolites and exhibit superior chromatographic behavior. Conclusion: An improved ultra-HPLC–MS/MS and structural approaches can accurately quantify 3,3-HPHPA and related analytes in human biological matrices.

The Microbiota–Gut–Brain Axis Heart Shunt Part I: The French Paradox, Heart Disease and the Microbiota

“…In that regard, cellular targets of flavonoids are likely kinases involved in signal transduction pathways like MEK, Raf and PI3K [61]. Recently, interest in microbial metabolism of polyphenols, phenolic acids and similar red wine components has grown and is a promising area of research for medicinal chemistry [62].…”

“…These small molecules are biomarkers of metabolism, where they could serve to chart health, disease, treatment efficacy or the progression of syndromes or sequelae related to co-metabolism between a host and its resident microorganisms. We call this aspect of analytical science metabolomics or the systems biology of metabolism [62].…”

“…TMANO formation in humans is poorly understood but it is purported to enter the same metabolic pathway as its precursors, which is one of several proposed that may contribute to bacterial pathobiology of clot-formation. We have quantified TMANO levels in many rodent tissues, fluids and brain as well as in human CSF, but the origin of TMANO in the brain is not well characterized [62] but it does illustrate an aspect of the Microbiota-Gut-Brain Axis Heart-Shunt, that microbe-derived metabolites reach the brain and compartments but also have an effect on the heart.…”

The Microbiota–Gut–Brain Axis–Heart Shunt Part II: Prosaic Foods and the Brain–Heart Connection in Alzheimer Disease

“…We are currently classifying small molecules from the microbiota, which originate distal to the brain and yet reach brain compartments. This happens via diverse indirect routes like the vagus nerve, as well as directly and systemically when the gut-derived or liver-modified compounds cross immune barriers to enter the brain and other immune-privileged compartments [4]. Whether these compounds are beneficial or deleterious, they need to reach a level that possibly can affect the brain to result in physiologic changes.…”

Identification and Quantification by Targeted Metabolomics of Antibiotic-Responsive Urinary Small Phenolic Molecules Derived from the Intestinal Microbiota in Mice

“…Even this approach, however, has shortcomings. A prototypical SPM of interest, 3-hydroxy-3-(3-hydroxyphenyl) propanoic acid (3,3-HPH-PA), has 12 structural isomers (C 9 H 10 O 4 ) differing in the position of a single hydroxyl group [17]. The isomers exhibit similar retention times and mass spectra and hence can easily be misidentified by LC/MS [13,18].…”