The Simultaneous Detection and Quantification of P-Aminobenzoic Acid and its Phase 2 Biotransformation Metabolites in Human Urine Using LC–MS/MS

Nortjé, Carla; Rensburg, Peet Jansen van; Cooke, Cecile; Erasmus, Elardus

doi:10.4155/bio.15.54

Cited by 10 publications

(14 citation statements)

References 49 publications

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“…They were referred by clinicians to our research unit for assessment of their biochemical profiles of phase I and phase II biotransformation. From assessments of this cohort of patients, we indicate a complementarity between a fatigue scale, medical symptoms and their biotransformation profiles and associated energy-related parameters [28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Biotransformation profiles from a cohort of chronic fatigue women in response to a hepatic detoxification challenge

et al. 2019

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Chronic fatigue, in its various manifestations, frequently co-occur with pain, sleep disturbances and depression and is a non-communicable condition which is rapidly becoming endemic worldwide. However, it is handicapped by a lack of objective definitions and diagnostic measures. This has prompted the World Health Organization to develop an international instrument whose intended purpose is to improve quality of life (QOL), with energy and fatigue as one domain of focus. To complement this objective, the interface between detoxification, the exposome, and xenobiotic-sensing by nuclear receptors that mediate induction of biotransformation-linked genes, is stimulating renewed attention to a rational development of strategies to identify the metabolic profiles in complex multifactorial conditions like fatigue. Here we present results from a seven-year study of a cohort of 576 female patients suffering from low to high levels of chronic fatigue, in which phase I and phase II biotransformation was assessed. The biotransformation profiles used were based on hepatic detoxification challenge tests through oral caffeine, acetaminophen and acetylsalicylic acid ingestion coupled with oxidative stress analyses. The interventions indicated normal phase I but increased phase II glucuronidation and glycination conjugation. Complementarity was indicated between a fatigue scale, medical symptoms and associated energy-related parameters by application of Chi-square Automatic Interaction Detector (CHAID) analysis. The presented study provides a cluster of data from which we propose that multidisciplinary inputs from the combination of a fatigue scale, medical symptoms and biotransformation profiles provide the rationale for the development of a comprehensive laboratory instrument for improved diagnostics and personalized interventions in patients with chronic fatigue with a view to improving their QOL.

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Section: Introductionmentioning

confidence: 99%

Biotransformation profiles from a cohort of chronic fatigue women in response to a hepatic detoxification challenge

et al. 2019

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“…The Agilent ZORBAX StableBond Phenyl 2.1 × 100 mm 1.8 micron column was purchased from Agilent Technologies. The method used for HA detection and quantification was adapted from the method described by Nortje et al . The source parameters of the MS were as follows: The gas temperature was 280°C, a gas flow of 6 L/min, the nebulizer set at 45 psi, sheath gas heater at 350°C, sheath gas flow of 7 L/min, a capillary voltage of 3000 V, and a nozzle voltage of 1500 V. Mobile phase A consisted of water with 0.1% formic acid, and mobile phase B consisted of 100% methanol.…”

Section: Methodsmentioning

confidence: 99%

New insights into the catalytic mechanism of human glycine N‐acyltransferase

Sluis

Ungerer

Nortjé

et al. 2017

J Biochem & Molecular Tox

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Even though the glycine conjugation pathway was one of the first metabolic pathways to be discovered, this pathway remains very poorly characterized. The bi-substrate kinetic parameters of a recombinant human glycine N-acyltransferase (GLYAT, E.C. 2.3.1.13) were determined using the traditional colorimetric method and a newly developed HPLC-ESI-MS/MS method. Previous studies analyzing the kinetic parameters of GLYAT, indicated a random Bi-Bi and/or ping-pong mechanism. In this study, the hippuric acid concentrations produced by the GLYAT enzyme reaction were analyzed using the allosteric sigmoidal enzyme kinetic module. Analyses of the initial rate (v) against substrate concentration plots, produced a sigmoidal curve (substrate activation) when the benzoyl-CoA concentrations was kept constant, whereas the plot with glycine concentrations kept constant, passed through a maximum (substrate inhibition). Thus, human GLYAT exhibits mechanistic kinetic cooperativity as described by the Ferdinand enzyme mechanism rather than the previously assumed Michaelis-Menten reaction mechanism.

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“…We recently described the challenge test protocol in a publication regarding a newly developed and validated analytical method for the quantification of PABA and its metabolites . In summary, challenge test kits were supplied to each volunteer that contained a detailed protocol for sample collection and dietary guidelines, a single 550 mg PABA capsule (Solgar, Leonia, NJ), a baseline urine sample bottle, six 1‐L urine containers, and labels for each container.…”

Section: Methodsmentioning

confidence: 99%

The Use of p‐Aminobenzoic Acid as a Probe Substance for the Targeted Profiling of Glycine Conjugation

Nortjé

Sluis

Dijk

et al. 2015

J Biochem & Molecular Tox

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Glycine conjugation facilitates the metabolism of toxic aromatic acids, capable of disrupting mitochondrial integrity. Owing to the high exposure to toxic substrates, characterization of individual glycine conjugation capacity, and its regulatory factors has become increasingly important. Aspirin and benzoate have been employed for this purpose; however, adverse reactions, aspirin intolerance, and Reye's syndrome in children are substantial drawbacks. The goal of this study was to investigate p-aminobenzoic acid (PABA) as an alternative glycine conjugation probe. Ten human volunteers participated in a PABA challenge test, and p-aminohippuric acid (PAHA), p-acetamidobenzoic acid, and p-acetamidohippuric acid were quantified in urine. The glycine N-acyltransferase gene of the volunteers was also screened for two polymorphisms associated with normal and increased enzyme activity. All of the individuals were homozygous for increased enzyme activity, but excretion of PAHA varied significantly (16-56%, hippurate ratio). The intricacies of PABA metabolism revealed possible limiting factors and the potential of PABA as an indicator of Phase 0 biotransformation.

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The Simultaneous Detection and Quantification of P-Aminobenzoic Acid and its Phase 2 Biotransformation Metabolites in Human Urine Using LC–MS/MS

Abstract: The developed LC-MS/MS assay is to our knowledge the first method available for the simultaneous quantification of PABA and its glycine conjugation metabolites in human urine and provides important quantitative data for studies of this phase 2 biotransformation pathway.

Cited by 10 publications

References 49 publications

Biotransformation profiles from a cohort of chronic fatigue women in response to a hepatic detoxification challenge

Biotransformation profiles from a cohort of chronic fatigue women in response to a hepatic detoxification challenge

New insights into the catalytic mechanism of human glycine N‐acyltransferase

The Use of p‐Aminobenzoic Acid as a Probe Substance for the Targeted Profiling of Glycine Conjugation

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