The metabolism of 4-trifluoromethoxyaniline and [13C]-4-trifluoromethoxyacetanilide in the rat: detection and identification of metabolites excreted in the urine by NMR and HPLC-NMR

Effect of Acupuncture on Rats with Acute Gouty Arthritis Inflammation: A Metabonomic Method for Profiling of Both Urine and Plasma Metabolic Perturbation

Acute gouty arthritis is a common inflammation model with multiple pathogenic mechanisms seen in clinical practice, for which acupuncture may potentially be an alternative therapy. To investigate the effect of acupuncture on acute gouty arthritis and search for its mechanism, a metabonomic method was developed in this investigation. Acute gouty arthritis model rats were induced by monosodium urate (MSU) crystals. The urine and plasma samples were collected at several time points and the endogenous metabolites were analyzed by an ultra-performance liquid chromatography coupled with a mass spectrometry (UPLC-MS). Data were analyzed using principal components analysis (PCA) and partial least squares (PLS) analysis to compare metabolic profiles of MSU crystal-induced acute gouty arthritis rats with MSU crystal-induced acute gouty arthritis, treated with acupuncture rats. The results showed that acupuncture could restore the metabolite network that disturbed by MSU administration. Our study indicates that UPLC-MS-based metabonomics can be used as a potential tool for the investigation of biological effect of acupuncture on acute gouty arthritis.

Perfluorinated carboxylic acids in directly fluorinated high-density polyethylene material

Perfluorinated carboxylic acids (PFCAs) are ubiquitous in the environment and have been detected in human blood worldwide. One potential route is direct exposure to PFCAs through contact with polymers that have been fluorinated through a process referred to as direct fluorination. PFCAs are hypothesized to be reaction byproducts of direct fluorination when trace amounts of oxygen are present. The objective of this research was to investigate whether PFCAs could be measured in directly fluorinated high-density polyethylene (HDPE) bottles. PFCAs were quantified using Soxhlet extraction with methanol, followed by LC-MS/MS analysis. Total concentrations of PFCAs ranged from 8.5 ± 0.53 to 113 ± 2.5 ng/bottle (1 L), with the short-chain PFCAs, perfluoropropanoic, perfluorobutanoic, perfluoropentanoic, and perfluorohexanoic acids, being the dominant congeners observed. Relative PFCA concentrations varied depending on fluorination level. Structural isomers were detected using (19)F NMR and are hypothesized to have formed during the fluorination process; NMR data revealed the linear isomer typically comprised 55% of the examined sample. Internally branched, isopropyl branched, and t-butyl PFCA isomers of varying chain length were also identified. Electrochemical fluorination was previously thought to be the only source of branched PFCA isomers. The observation here of branched isomers suggests direct fluorination may be an additional source of exposure to these chemicals. The purpose of this study was to measure PFCAs in directly fluorinated material, serving as a previously unidentified source contributing to the environmental load of PFCAs, with potential for human exposure.

Mixture analysis by NMR as applied to fruit juice quality control

Nuclear magnetic resonance (NMR) spectroscopy is rapidly gaining importance in mixture analysis, originally driven by the pharmaceutical and nowadays also by clinical applications within metabonomics. Quality control of food-related material has very similar requirements, as it also deals with mixtures, and many of the compounds found in body fluids are analyzed as well. NMR allows analysis in two ways within one experiment: namely, targeted and untargeted. Targeted stands for the safe identification and consequent quantification of individual compounds, whereas untargeted means the detection of all deviations visible by NMR using statistical analysis based on normality models. Very important is the stability and reproducibility of the NMR instrumentation used, and this means inherent minimized system internal variance. NMR is especially suited for such requirements, as it allows detection of the smallest concentration changes of many metabolites simultaneously. High-throughput flow-injection NMR as the basis for fruit juice screening allows low cost per sample and delivers substantially more relevant information than any other method and is probably the only method to produce such results.

Metabolism of [14C]-5-chloro-1,3-benzodioxol-4-amine in male Wistar-derived rats following intraperitoneal administration

[14C]-5-chloro-1,3-benzodioxol-4-amine was administered intraperitoneally (i.p.) to bile duct-cannulated rats (Alpk:ApfSD, Wistar derived) at 25 mg kg-1 to determine the rates and routes of excretion of the compound and to investigate its metabolic fate. A total of 89.1% of the dose was excreted in the 48 h following administration, the majority being recovered in the urine during the first 12 h. The main metabolite in both urine and bile, detected by high-performance liquid chromatography (HPLC) with radioprofiling and mass spectrometry, was identified as a demethylenated monosulfate conjugate. Unchanged parent compound formed a major component of the radiolabel excreted in urine and, in addition to unchanged parent and demethylenated sulphate conjugate, a large number of minor metabolites were detected in urine and bile. The overall metabolic fate of 5-chloro-1,3-benzodioxol-4-amine in the rat was complex, with some similarities to previously studied methylenedioxyphenyl compounds.

Metabolism of 3-chloro-4-fluoroaniline in rat using [14C]-radiolabelling,19F-NMR spectroscopy, HPLC-MS/MS, HPLC-ICPMS and HPLC-NMR

The metabolic fate of 3-chloro-4-fluoroaniline was investigated in rat following intraperitoneal (i.p.) administration at 5 and 50 mg kg(-1) using a combination of HPLC-MS, HPLC-MS/MS, (19)F-NMR spectroscopy, HPLC-NMR spectroscopy and high-pressure liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS) with (35)Cl and (34)S detection. The metabolism of 3-chloro-4-fluoroaniline at both doses was rapid and extensive, to a large number of metabolites, with little unchanged compound excreted via the urine. Dosing at 5 mg kg(-1) with [(14)C]-labelled compound enabled the comparison of standard radioassay analysis methods with (19)F-NMR spectroscopy. (19)F-NMR resonances were only readily detectable in the 0-12 h post-dose samples. Dosing at 50 mg kg(-1) allowed the facile and specific detection and quantification of metabolites by (19)F-NMR spectroscopy. Metabolite profiling was also possible at this dose level using HPLC-ICPMS with (35)Cl-specific detection. The principal metabolites of 3-chloro-4-fluoroaniline were identified as 2-amino-4-chloro-5-fluorophenyl sulfate and 2-acetamido-4-chloro-5-fluorophenyl glucuronide. N-acetylation and hydroxylation followed by O-sulfation were the major metabolic transformations observed.

Reductive defluorination of perfluorooctane sulfonate

Perfluorooctane sulfonate (PFOS) is under increased scrutiny as an environmental pollutant due to recent reports of its worldwide distribution, environmental persistence, and bioaccumulation potential. The susceptibility of technical PFOS and PFOS branched isomers to chemical reductive dehalogenation with vitamin B12 (260 microM) as catalyst and Ti(III)-citrate (36 mM) as bulk reductant in anoxic aqueous solution at 70 degrees C and pH 9 was evaluated in this study. Defluorination was confirmed by fluoride release measurements of 18% in technical PFOS, equivalent to the removal 3 mol F-/mol PFOS, and 71% in PFOS branched isomers equivalent to the removal of 12 mol F-/mol PFOS. Degradation of PFOS was further confirmed by monitoring the disappearance of PFOS compounds with reaction time by suppressed conductivity ion chromatography, LC-MS/MS, and 19F NMR studies. The PFOS compounds differed in their susceptibility to reductive degradation by vitamin B12Ti(III) citrate. Chromatographic peaks corresponding to branched PFOS isomers disappeared whereas the peak corresponding to linear PFOS was stable. To our knowledge this is the first report of reductive dehalogenation of PFOS catalyzed by a biomolecule.

LC-NMR-MS in drug discovery

Nuclear magnetic resonance spectroscopy (NMR) is arguably the most versatile analytical platform for complex mixture analysis. Specifically, interfacing liquid chromatography with parallel NMR and mass spectrometry (LC-NMR-MS) gives comprehensive structural data on metabolites of novel drugs in development. Applications in natural product, combinatorial chemistry and drug metabolism studies are reviewed. Microcoil probes and capillary separation methods have enormous potential. Recent innovations to improve NMR detection limits include CryoFlowProbes and on-line solid-phase extraction (LC-SPE-NMR). These state-of-the-art analytical platforms are widely applicable to identifying novel candidate drugs from diverse complex mixtures within a drug discovery strategy.

The metabolism of 2-trifluormethylaniline and its acetanilide in the rat by 19F NMR monitored enzyme hydrolysis and 1H/19F HPLC-NMR spectroscopy

The urinary excretion profile and identity of the metabolites of 2-trifluoromethyl aniline (2-TFMA) and 2-trifluoromethyl acetanilide (2-TFMAc), following i.p. administration to the rat at 50 mg kg(-1), were determined using a combination of 19F NMR monitored enzyme hydrolysis, SPEC-MS and 19F/1H HPLC-NMR. A total recovery of approximately 96.4% of the dose was excreted into the urine as seven metabolites. The major routes of metabolism were N-conjugation (glucuronidation), and ring-hydroxylation followed by sulphation (and to a lesser extent glucuronidation). The major metabolites excreted into the urine for both compounds were a labile N-conjugated metabolite (a postulated N-glucuronide) and a sulphated ring-hydroxylated metabolite (a postulated 4-amino-5-trifluoromethylphenyl sulphate) following dosing of 2-TFMA. These accounted for approximately 53.0 and 31.5% of the dose, respectively. This study identifies problems on sample component instability in the preparation and analysis procedures.