Investigating a systematic and widespread misidentification in the metabolic profiling literature: phenylacetylglutamine and phenylacetylglycine signal misassignment in proton NMR spectra of human and rodent urine
Author(s)
Type
Journal Article
Abstract
Accurate assignment of endogenous and exogenous constituents within complex biological matrices remains a central challenge in metabolomics. Phenylacetylglutamine (PAGln) and phenylacetylglycine (PAGly) are terminal metabolites of the host-microbial co metabolism of phenylalanine, predominantly observed in humans and rodents, respectively. Motivated by a pervasive misidentification within the literature, we demonstrate that PAGln in human urine has been erroneously identified as PAGly in 82 of 166 NMR-based studies, yielding an estimated misannotation rate of 49%. Herein, we provide definitive assignments for both PAGly and PAGln, and present a comprehensive statistical evaluation of the NMR resonances attributed to both species, alongside their quantitative determination via targeted line-fitting approaches in extensive human and rodent urine samples obtained from the INTERSALT cohort (N = 1589) and the historical COMET study (N = 4399) respectively. In agreement with canonical hepatic metabolic pathways, PAGln was found to be exclusively present in human urine, whereas PAGly was restricted to rodent (i.e., rat and mouse) urine. These findings underscore the need for systematic re-evaluation of prior metabolomic annotations involving these structurally related yet biochemically distinct metabolites.
Date Issued
2025-11-04
Date Acceptance
2025-10-15
Citation
Analytical Chemistry, 2025, 97 (43), pp.24126-24135
ISSN
0003-2700
Publisher
American Chemical Society
Start Page
24126
End Page
24135
Journal / Book Title
Analytical Chemistry
Volume
97
Issue
43
Copyright Statement
Copyright © 2025 American Chemical Society. This publication is licensed under CC-BY-NC-ND 4.0 .
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/41133822
Subjects
BLOOD-PRESSURE
Chemistry
Chemistry, Analytical
GLUTAMINE
HEALTH
HUMAN-BODY
HYPERTENSIVE-RATS
IDENTIFICATION
PHENYLACETIC ACID
Physical Sciences
RESPONSES
Science & Technology
SERUM
SPECTROSCOPY
Publication Status
Published
Coverage Spatial
United States
Date Publish Online
2025-10-24