Identification and structural characterization of in vivo metabolites of balofloxacin in rat plasma, urine and feces samples using Q-TOF/LC/ESI/MS/MS : In silico toxicity studies

Review on in vivo profiling of drug metabolites with LC-MS/MS in the past decade

Metabolite profiling is an indispensable part of drug discovery and development, enabling a comprehensive understanding of the drug's metabolic behavior. Liquid chromatography-mass spectrometry facilitates metabolite profiling by reducing sample complexity and providing high sensitivity. This review discusses the in vivo metabolite profiling involving LC-MS/MS and the utilization of QTOF, QQQ mass analyzers with a particular emphasis on a mass filter. Further, a summary of sample extraction procedures in biological matrices such as plasma, urine, feces, serum and hair as in vivo samples are outlined. toward the end, we present 15 case studies in biological matrices and their LC-MS/MS conditions to understand the metabolic disposition.

Structural Characterization of the Millennial Antibacterial (Fluoro)Quinolones-Shaping the Fifth Generation

The evolution of the class of antibacterial quinolones includes the introduction in therapy of highly successful compounds. Although many representatives were withdrawn due to severe adverse reactions, a few representatives have proven their therapeutical value over time. The classification of antibacterial quinolones into generations is a valuable tool for physicians, pharmacists, and researchers. In addition, the transition from one generation to another has brought new representatives with improved properties. In the last two decades, several representatives of antibacterial quinolones received approval for therapy. This review sets out to chronologically outline the group of approved antibacterial quinolones since 2000. Special attention is given to eight representatives: besifloxacin, delafoxacin, finafloxacin, lascufloxacin, nadifloxacin and levonadifloxacin, nemonoxacin, and zabofloxacin. These compounds have been characterized regarding physicochemical properties, formulations, antibacterial activity spectrum and advantageous structural characteristics related to antibacterial efficiency. At present these new compounds (with the exception of nadifloxacin) are reported differently, most often in the fourth generation and less frequently in a new generation (the fifth). Although these new compounds' mechanism does not contain essential new elements, the question of shaping a new generation (the fifth) arises, based on higher potency and broad spectrum of activity, including resistant bacterial strains. The functional groups that ensured the biological activity, good pharmacokinetic properties and a safety profile were highlighted. In addition, these new representatives have a low risk of determining bacterial resistance. Several positive aspects are added to the fourth fluoroquinolones generation, characteristics that can be the basis of the fifth generation. Antibacterial quinolones class continues to acquire new compounds with antibacterial potential, among other effects. Numerous derivatives, hybrids or conjugates are currently in various stages of research.

An Entire Process Optimization Strategy for Comprehensive In Vivo Metabolite Profiling of Prucalopride in Rats Based on Ultra-Performance Liquid Chromatography With Q-Exactive Hybrid Quadrupole-Orbitrap High-Resolution Mass Spectrometry

Prucalopride was widely used for chronic constipation, which is difficult to be adequately relieved by laxatives in adult patients in clinic. Due to the difficulty in metabolite identification, metabolic process of prucalopride had not been investigated in vivo. In this study, an efficient strategy was proposed for comprehensive metabolite profiling of prucalopride after oral administration in rat plasma, urine, and feces samples. This strategy was composed of five steps. First, the samples at multiple time points after oral administration were collected to increase the representativeness of the samples. Second, different sample preparation methods were investigated to obtain superior extraction efficiency. Third, the raw data of test sample and blank sample were acquired using ultra-performance liquid chromatography with Q-Exactive hybrid quadrupole–orbitrap high-resolution accurate mass spectrometry under the positive and negative full-scan/dd MS² mode. Fourth, combined mass defect filter with background subtraction model in soft of compound discovery, all peaks were constructed to filter potential metabolites after retention time alignment and ion filtration, which could remove large amounts of interference ions. Besides, it can predict potential biotransformation, promoting to understand how to metabolize the drug. This provides multiple possibilities and prevents us conjecturing the potential metabolites blindly. Finally, the verification procedure was implemented through exporting the structure and MS² spectrum to the analytical tool of Mass Frontier. The proposed strategy significantly improved the targeted detection and identification for metabolites in vivo. A total of 47 metabolites were tentatively characterized in the plasma, urine, and feces samples after oral administration of prucalopride. This study could provide a valuable reference for systematic metabolite profile of drug in vivo.

Liquid chromatography-three-dimensional mass spectrometry enables confirmative structural annotation of cistanoside F metabolites in rat

Clarification the existence forms, including prototype and metabolite(s) is the prerequisite for understanding in-depth the therapeutic mechanisms of a given agent, particularly when oral administration. However, it is still a long distance for unambiguous structural identification of metabolites even employing the cutting-edge MS/MS technique, and the determinant obstacle is produced by its inherent isomer-blind disadvantage. To tackle with this drawback, online energy-resolved mass spectrometry (online ER-MS) was introduced to enable isomeric discrimination after that high-resolution MS/MS provided empirical molecular formula as well as substructures. In-depth metabolic characterization of cistanoside F (CF), an effective natural product, was conducted as a proof-of-concept for the new strategy namely three-dimensional MS that was configured by MS¹, MS² and online ER-MS as 1st, 2nd, and 3rd dimensions, respectively. Sensitive metabolite detection was assisted by predictive multiple-reaction monitoring function on Qtrap-MS, and the empirical formulas of all metabolites were calculated from the quasi-molecular ions yielded from IT-TOF-MS. Subsequently, substructures of each metabolite were constructed by combining the calculated element compositions and the well-defined mass fragmentation pathways. Finally, online ER-MS was responsible to generate optimal collision energies for bonds-of-interest, and enabled rational selection among candidate structures. A total of thirteen metabolites were detected and confirmatively identified in rat after oral treatment of CF using LC-3D MS. Acyl-migration, hydrolysis and sulfation played key roles for the metabolic fate of CF. More importantly, LC-3D MS is an eligible tool to achieve confidence-enhanced structural annotation of metabolites in biological matrices because of the unique isomeric differentiation ability from online ER-MS.

Metabolites profiling and pharmacokinetics of troxipide and its pharmacodynamics in rats with gastric ulcer

Troxipide is widely used to treat gastric ulcer (GU) in the clinic. However, a lack of systematic metabolic, pharmacokinetic and pharmacological studies limits its clinical use. This study aimed to firstly explore the metabolic, pharmacokinetic and pharmacological mechanisms of troxipide in rats with GU compared to normal control (NC) rats. First, metabolic study was perormed by a highly selective, high-resolution mass spectrometry method. A total of 45 metabolites, including 9 phase I metabolites and 36 phase II metabolites, were identified based on MS/MS spectra. Subsequently, the pharmacokinetics results suggested that the Cmax, Ka, t1/2, AUC(0-t) and AUC(0-∞) of troxipide were significantly increased in rats with GU compared with NC rats. The Vz, K10 and absolute bioavailability of troxipide were obviously decreased in rats with GU compared with NC rats, and its tissue distribution (in the liver, lung and kidney) was significantly different between the two groups of rats. Additionally, the pharmacodynamic results suggested that the levels of biochemical factors (IL-17, IL-6, TNF-α, IFN-γ, AP-1, MTL, GAS, and PG-II) were significantly increased, the PG-Ӏ level was obviously decreased, and the protein expression levels of HSP-90, C-Cas-3 and C-PARP-1 were markedly increased in rats with GU compared with NC rats. The above results suggested that the therapeutic mechanisms underlying the metabolic, pharmacokinetic and pharmacological properties of troxipide in vivo in rats deserve further attention based on the importance of troxipide in the treatment of GU in this study, and these mechanisms could be targets for future studies.

Exploring stereoselective excretion and metabolism studies of novel 2-(2-hydroxypropanamido)-5-trifluoromethyl benzoic acid enantiomers

R-/S-2-(2-Hydroxypropanamido)-5-trifluoromethyl benzoic acid (R-/S-HFBA), as a novel COX inhibitor, was firstly reported to have remarkable anti-inflammatory and antiplatelet aggregation activities by our group. In our previous study, stereoselective differences in pharmacokinetics were found between HFBA enantiomers after oral and intravenous administration of each enantiomer to rats. The discrepancies might be associated with the excretion and metabolism of the two enantiomers. In this research, an UHPLC-MS/MS method was established and validated for quantification of R-/S-HFBA in rats urine, feces and bile samples in excretion study. Moreover, an ultra high performance liquid chromatography coupled with Fourier transform ion cyclotron resonance mass spectrometry (UHPLC-FT-ICR-MS) method was employed to understand the metabolism of R-/S-HFBA in rats. Results showed that the total cumulative excretion of R-/S-HFBA in three routes were 65.8% and 58.5% of the dose, respectively. The urinary excretion of R-/S-HFBA was the main route, which accounted for 40.2% and 31.7% respectively; the cumulative biliary excretion of R-/S-HFBA were 11.3% and 7.4%; the cumulative amounts of R-/S-HFBA excreted directly via feces without absorption from the gastrointestinal tract were 14.3% and 19.4%, respectively. R-/S-HFBA existed stereoselective discrepancy in excretion. In addition, 8 metabolites of S-HFBA were detected and tentatively identified including glucuronidation, glycine and N-acetyl conjugation while R-HFBA existed 7 metabolites without glycine conjugation. Formation of metabolites of R-/S-HFBA also exhibited stereoselectivity. In summary, these new findings on excretion and metabolism of R-/S-HFBA provided valuable information for stereoselective pharmacokinetics and were greatly helpful for further investigation, such as safety and mechanism of action.

R-/S-2-(2-Hydroxypropanamido)-5-trifluoromethyl benzoic acid (R-/S-HFBA), as a novel COX inhibitor, was firstly reported to have remarkable anti-inflammatory and antiplatelet aggregation activities by our group.

Pharmacokinetics and Metabolite Profiling of Trepibutone in Rats Using Ultra-High Performance Liquid Chromatography Combined With Hybrid Quadrupole-Orbitrap and Triple Quadrupole Mass Spectrometers

Trepibutone was widely used for cholelithiasis, cholecystitis, biliary tract dyskinesia, cholecystectomy syndrome, and chronic pancreatitis in clinic. However, few investigations on trepibutone have been conducted. In this study, an accurate, sensitive, and selective analytical method was developed and successfully applied to assess the pharmacokinetic behavior of trepibutone in rats. Trepibutone and carbamazepine (internal standard, IS) were quantified using multiple reaction monitoring (MRM) mode with the transitions of m/z 311.09→265.08 and m/z 237.06→194.08, respectively. The linearity, precision, accuracy, extraction recovery, matrix effect, and stability of the established method were all excellent within acceptable range. A total of 30 metabolites were identified in plasma and urine by Q-Exactive high resolution mass spectrometry, and several common metabolic pathways were observed such as dealkylation, oxidation, reduction, glucuronidation, and so on. This research provides more information on trepibutone in pharmacodynamics and toxicology and will assist the usage of trepibutone in clinical.