Multiple Reaction Monitoring Detection Research Articles

Liquid Chromatography-Tandem Mass Spectrometry Method for Therapeutic Drug Monitoring of Dalbavancin in Plasma of Pediatric and Young Adult Patients.

Dalbavancin, an antimicrobial lipoglycopeptide, is authorized in Europe for treating acute bacterial infections of the skin and skin structures in adults and pediatric patients aged 3 months and older. However, off-label dosing regimens have been proposed for various indications beyond acute bacterial infections of the skin and skin structures. This study presents a novel bioanalytical method using liquid chromatography-tandem mass spectrometry to quantify dalbavancin in low-volume plasma samples (50 μL). The method underwent validation in accordance with international guidelines for bioanalytical method validation and was applied to 9 clinical samples obtained from pediatric and young adult patients undergoing dalbavancin therapy. Liquid chromatography-tandem mass spectrometry analyses were conducted at the G. Gaslini Institute in Genoa, Italy, utilizing an Ultimate 3000 ultra high performance liquid chromatography system coupled to a TSQ Quantiva Triple Quadrupole system (Thermo Fisher Scientific, Milan, Italy). The analytical procedure involved the addition of deuterated dalbavancin as internal standard and a rapid extraction from 50 µL of human plasma, followed by chromatographic separation on a Thermo Scientific Accucore Polar Premium column. Accurate quantification of the analyte was achieved through multiple reaction monitoring detection. The assay exhibited linearity within the concentration range of 0.66-400 mcg/mL in plasma, demonstrating accuracy and reproducibility in the absence of matrix effects. Stability testing was conducted on both quality controls and real samples to establish a robust protocol under real-life conditions. This fast and reliable dalbavancin quantitation method could improve current pediatric clinical practice by enabling data collection for future dose recommendations in special patient populations.

Development and Validation of a Sensitive Liquid Chromatography-Tandem Mass Spectrometry Method for Therapeutic Drug Monitoring of Ceftolozane and Tazobactam in Human Plasma Microsamples.

Ceftolozane/tazobactam (C-T) is a novel beta-lactam/beta-lactamase inhibitor combination approved for the treatment of various infections caused by difficult-to-treat Pseudomonas aeruginosa. In critically ill patients, C-T may exhibit significant pharmacokinetic variability, both between individuals and within individuals, warranting therapeutic drug monitoring for clinical purposes. We aim to develop and validate a novel and sensitive analytical method for concurrently determining C and T in human plasma microsamples (3μL). The method was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with positive electrospray ionization and multiple reaction monitoring (MRM) detection modes, employing specific mass transitions for both drugs. Sample preparation was simple, and the chromatographic run lasted only 4 minutes. Validation was conducted according to European Medicines Agency (EMA) guidelines, encompassing specificity, sensitivity, linearity, precision, accuracy, matrix effect, extraction recovery, limit of quantification, and drug stability. The validated method was applied to measure C and T in 32 plasma samples collected from critically ill patients with multidrug-resistant, gram-negative, bacterial infections. The method ensured accurate (BIAS% 2.1-9.6 for C and -2.2 to 15.2 for T) and precise intraday CV% for C: 6.7-5.5; for T: 1.3-8.9; interday CV% for C 6.0-10.8; for T 4.1-10.2) measurements of C-T over a wide concentration range (0.2-200.0 mg/L for C and 0.1-100.0 mg/L for T). Overall, the recovery at quality control concentration levels was high for both C and T (mean values: 90-91 for C and 89-92 for T). Analyte stability was satisfactory in both human plasma and extracts under various storage conditions. The clinical applicability of the assay was confirmed by the reliably quantifying C and T in clinical plasma samples. The developed and validated LC-MS/MS method is sensitive and suitable for monitoring C and T in human plasma microsamples.

A simple and sensitive LC-MS/MS method for the determination of loganic acid in rat plasma and its pharmacokinetic analysis.

Loganic acid is an iridoid compound extracted from Gentianaceae plant Gentiana macrophylla Pall. It can effectively inhibit inflammation and tumor migration and has antioxidant activity. In this paper, we establish a simple, fast, sensitive and validated LC-MS method with the purpose of quantification of loganic acid in rat plasma with gliclazide as an internal standard (IS). Methanol was used to precipitate the protein in the plasma sample, and a C18 column (2.1 × 50 mm, 1.7μm) was used for the separation of the target compound. Meanwhile, 0.1% formic acid water-methanol was employed as the mobile phase. Multiple reaction monitoring detection mode was adopted in detection with m/z 375.1 > 213.2 for loganic acid and m/z 322.1 > 169.9 for the IS, respectively, in negative ion scan mode. The linear range of calibration curve was 5.77-11,540.00 ng/ml, and the lower limit of detedtion was 2.89 ng/ml. The inter-day and intra-day precision and accuracy were <15% for lower limit of quantitation, low, middle and high quality control samples. This method was successfully used for the pharmacokinetic study of loganic acid in rat plasma at a dose range of 50-150 mg/kg for oral administration and 2mg/kg for intravenous administration. The pharmacokinetic results showed that the oral bioavailability of loganic acid was low (2.71-5.58%).

Determination of warfarin in volumetric absorptive microsampling by liquid chromatography-tandem mass spectrometry

ObjectiveThis study aims to develop and validate bioanalytical method for quantifying warfarin in VAMS samples using liquid chromatography tandem mass spectrometry (LC-MS/MS), directly implementing the method to patients receiving warfarin therapy. MethodsThe UPLC-MS/MS method was developed and optimized, with quercetin as the internal standard. Sample preparation was carried out using protein precipitation with methanol-acetonitrile (1:3 v/v). ResultsChromatographic separation was achieved using Acquity® UPLC BEH C18 column with 0.1 % formic acid-acetonitrile-methanol (30:69:1 v/v) as mobile phase, in isocratic elution. Multiple Reaction Monitoring (MRM) detection was done using m/z values of 307.10 → 161.06 for warfarin and 301.03 → 150.98 for quercetin as internal standard, using Electrospray Ionization (ESI) negative ion source. The clinical application of the bioanalytical method was carried out on 25 patients receiving warfarin therapy at Universitas Indonesia Hospital and warfarin levels were well within the calibration range from 6.05 to 431.39 ng/mL. ConclusionA novel method has been developed to analyze warfarin in VAMS samples. This method has been fully validated according to guideline from FDA 2022 and is linear in the range of 5–500 ng/mL and the value of r ≥ 0.9977, and successfully applied for the analysis of warfarin in VAMS samples of clinical patients.

A Sensitive Liquid Chromatography-Tandem Mass Spectrometry Method for Measuring Fosfomycin Concentrations in Human Prostatic Tissue.

The aim of this study was to develop and validate a fast and sensitive bioanalytical method for the accurate quantification of fosfomycin concentrations in human prostatic tissue. The sample preparation method only required milligrams of tissue sample. Each sample was mixed with two times its weight of water and homogenized. A methanol solution that was three times the volume of the internal standard (fosfomycin-13C3) was added, followed by vortex mixing and centrifugation. After its extraction from the homogenized prostatic tissue, fosfomycin was quantified by means of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) triple quadrupole system operating in negative electrospray ionization and multiple reaction monitoring detection mode. The analytical procedure was successfully validated in terms of specificity, sensitivity, linearity, precision, accuracy, matrix effect, extraction recovery, limit of quantification, and stability, according to EMA guidelines. The validation results, relative to three QC levels, were 9.9% for both the within-day and inter-day accuracy (BIAS%); 9.8% for within-day precision; and 9.9 for between-day precision. A marked matrix effect was observed in the measurements but was corrected by normalization with the internal standard. The average total recovery was high (approximatively 97% at the three control levels). The dynamic range of the method was 0.1-20 μg/g (R2 of 0.999). Negligible carry-over was observed after the injection of highly concentrated samples. F in the sample homogenate extracts was stable at 10 °C and 4 °C for at least 24 h. In the tissue sample freeze-thaw experiments, a significant decrease in F concentrations was observed after only two cycles from -80 °C to room temperature. The novel method was successfully applied to measure fosfomycin in prostatic tissue samples collected from 105 patients undergoing prostatectomy.

Innovative LC-MS/MS method for therapeutic drug monitoring of fenfluramine and cannabidiol in the plasma of pediatric patients with epilepsy

We present a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying fenfluramine (FFA), its active metabolite norfenfluramine (norFFA), and Epidyolex®, a pure cannabidiol (CBD) oral solution in plasma. Recently approved by the EMA for the adjunctive treatment of refractory seizures in patients with Dravet and Lennox-Gastaut syndromes aged above 2 years, FFA and CBD still do not have established therapeutic blood ranges, and thus need careful drug monitoring to manage potential pharmacokinetic and pharmacodynamic interactions. Our method, validated by ICH guidelines M10, utilizes a rapid extraction protocol from 100 µL of human plasma and a reversed-phase C-18 HPLC column, with deuterated internal standards. The Thermofisher Quantiva triple-quadrupole MS coupled with an Ultimate 3000 UHPLC allowed multiple reaction monitoring detection, ensuring precise analyte quantification. The assay exhibited linear responses across a broad spectrum of concentrations: ranging from 1.64 to 1000 ng/mL for both FFA and CBD, and from 0.82 to 500 ng/mL for norFFA. The method proves accurate and reproducible, free from matrix effect. Additionally, FFA stability in plasma at 4 °C and −20 °C for up to 7 days bolsters its clinical applicability. Plasma concentrations detected in patients samples, expressed as mean ± standard deviation, were 0.36 ± 0.09 ng/mL for FFA, 19.67 ± 1.22 ng/mL for norFFA. This method stands as a robust tool for therapeutic drug monitoring (TDM) of FFA and CBD, offering significant utility in assessing drug-drug interactions in co-treated patients, thus contributing to optimized patient care in complex therapeutic scenarios.

Development and validation of ivermectin quantification method in volumetric absorptive microsampling using liquid chromatography-tandem mass spectrometry

BackgroundIvermectin is a broad-spectrum anthelmintic used to control onchocerciasis from nematode parasites. As an anthelmintic, ivermectin is designed to have high levels in the gastrointestinal tract, so that the systemic intake is relatively low. Due to the very small concentration of ivermectin, a selective and sensitive approach is needed for the analysis of ivermectin in blood. Several methods have been developed using plasma and Dried Blood Spots, but there are still shortcomings due to hematocrit effects. Therefore, this study was conducted to establish a validated ivermectin analysis method with doramectin as the internal standard in using Ultra High-Performance Liquid Chromatography-Tandem Mass Spectrometry. MethodsMass spectrometry equipped with triple quadrupole and positive electrospray ionization mode was used to conduct the analysis. For the biological matrix, whole blood was used by Volumetric Absorptive Microsampling and extracted using a protein precipitation technique with a combination of acetonitrile and methanol (1:1). VAMS has some advantages such as not being affected by hematocrit, requires a small and fixed volume of sample, also a more efficient sampling process. ResultsThe optimum conditions were achieved with an Acquity® UPLC BEH C18 column (1,7 μm; 2.1 × 100 mm); extracted-flow rate was 0,2 mL/min; mobile phase was 5 mM ammonium formate pH 3.00 and acetonitrile (10:90) with isocratic elution. Multiple Reaction Monitoring (MRM) detection by m/z values was 892.41 > 569.5 for ivermectin and 916,41 > 331,35 for doramectin. ConclusionThe method has been appropriately validated in compliance with the 2018 guidelines laid out by the US Food and Drug Administration. Resulting the minimum detection (LLOQ) was 1 ng/mL with a linear concentration range spanning from 1 to 150 ng/mL.

A novel UHPLC-MS/MS method for trace level identification and quantification of genotoxic impurity 2-(2-chloroethoxy) ethanol in quetiapine fumarate

A selective and sensitive new reversed-phase method was developed and validated by using Waters Acquity UHPLC system coupled with Waters Micromass Quattro PremierXE (MS/MS) to identify and quantify the genotoxic impurity 2-(2-chloroethoxy) ethanol at trace level (∼2.0 ppm) in quetiapine fumarate. The method used positive ion electrospray ionization with a multiple reaction monitoring detection mode using ACE3 C18(100 mm × 4.6 mm × 3.0 µm) column. For analysis, an isocratic program was developed using 0.01 M ammonium acetate in Milli-Q water (mobile phase A) and methanol (mobile phase B) in 20:80v/v ratio. Elution of 2-(2-chloroethoxy) ethanol was monitored using triple quadrupole mass spectrometer with an injection volume of 10 μl, a column oven temperature of 40 °C, an auto-sampler temperature of 15 °C, and flow rate of 0.5 mL/min. The retention time of 2-(2-chloroethoxy) ethanol was observed at 2.38 min. The LOQ and LOD were determined at concentrations of 0.235 ppm and 0.070 ppm respectively. The correlation coefficient R 2 was 0.9983 and the percent recoveries of method range from 98.1% to 114.0%. The method was successfully validated according to International Council for Harmonization requirements (ICH Q2(R1) and ICH M7(R1)) for genotoxic impurities. The method was sensitive, selective, accurate and precise and therefore can be used for identification and quantification of genotoxic impurity 2-(2-chloroethoxy) ethanol in quetiapine fumarate.

Development of an UHPLC-MS/MS method to determine cutaneous biodistribution of cannabidiol after topical application of cannabidiol gel assisted by iontophoresis.

Cannabidiol has potential for use in skin disease therapy, so it is important to know the cutaneous biodistribution of cannabidiol after topical application of cannabidiol formulations. However, currently existing quantification methods for the investigation of cannabidiol skin distribution are not optimal. This study aimed to establish a method for the determination of cannabidiol in skin samples by UHPLC-MS/MS. A BEH C18 (50.0 × 2.1mm, 2.5μm) column was used; the mobile phase consisted of acetonitrile-0.1% formic acid (70:30, v/v), the flow rate was 0.2μl·min-1 and the column temperature was 30°C. Positive-ion mode with multiple reaction monitoring detection was used to quantify cannabidiol (m/z 315.1 → 193.1) while diphenhydramine (m/z 256.3 → 167.08) served as the internal standard. Good linearity was shown in the range of 1-200 ng·ml-1 for cannabidiol with correlation coefficients of >0.999. The LLOQ was 1ng·ml-1 . The intra-day and inter-day RSDs of cannabidiol were all <2%. A cryo-sectioning technique combined with the UHPLC-MS/MS method was used to successfully determine cannabidiol levels in a series of very thin skin layers.

Development of analytical methods fort he quantitative analysis of the enzyme abundance and activity in the arachidonic acid cascade

The arachidonic acid (ARA) cascade is a key regulatory pathway where eicosanoids and other oxylipins are formed via the oxidation of polyunsaturated fatty acids. These oxylipins are involved in controlling physiological functions such as vascular tone, blood clotting and immune regulation. Changes in the oxylipin pattern can be caused by direct enzyme inhibition or modulated gene expression. In order to understand the effect mechanisms modulating the ARA cascade it is essential to not only investigate the metabolite, i.e. oxylipin, concentrations but also the abundances of the enzymes involved in their formation. For this reason, a quantitative targeted proteomics method for the ARA cascade was developed within this thesis.A detailed workflow for method development was established where enzyme/protein levels are measured via sequence‐specific, representative peptides chosen on the basis of several criteria. With liquid chromatography‐tandem mass spectrometry‐based analysis, the cyclooxygenase (COX) pathway of the ARA cascade was investigated in human colon carcinoma cell lines and primary macrophages where strong correlations were found between the oxylipins formed via the COX pathway and the COX‐2 abundance.The modulating effects of polyphenols on the 5‐lipoxygenase (LOX) pathway of the ARA cascade were investigated in cell‐free enzyme assays and human neutrophils. Resveratrol, its dimer ɛ‐viniferin and a resveratrol imine analogue directly inhibited the 5‐LOX with micromolar potencies and modulated the total oxylipin pattern in the neutrophils with remarkably different effects. Genistein did not act as a 5‐LOX inhibitor in the cell‐free assay but the modulated oxylipin pattern in the cells suggests a global cellular interference.The enzymes of the LOX pathway were included in the targeted proteomics method which together with an extended targeted oxylipin metabolomics platform enables a sensitive multi‐ omics analysis of the ARA cascade in a single sample. The comparison of the multiple reaction monitoring (MRM) detection and the MRM^‐based approach with an additional fragmentation step demonstrated that MRM is more favorable in targeted proteomics due to its higher sensitivity, greater linear range and higher multiplexing capacities. The analysis with the multi‐ omics approach showed that the 5 LOX protein is induced together with its product formation during the differentiation of human monocytic THP 1 cells to macrophages. M1‐like human primary macrophages were also characterized by the abundance of 5‐LOX and its activating protein (FLAP), while 15‐LOX and 15‐LOX‐2 dominated the protein pattern of the M2 like macrophages accompanied by high levels of the oxylipins formed via these enzymes. The developed methodology allows mechanistic investigation of a modulation of the ARA cascade as demonstrated by lipo‐poly‐saccharide stimulation as well as pharmaceutical treatment of the cells.Overall, with this thesis, a new quantitative proteomics strategy for the enzymes of the ARA cascade is established which can be easily extended to further proteins. The use of this technique in combination with targeted oxylipin metabolomics has provided new insights into the mechanisms involved in the modulation of the ARA cascade in human immune cells.

Simultaneous Quantification of Ivacaftor, Tezacaftor, and Elexacaftor in Cystic Fibrosis Patients’ Plasma by a Novel LC–MS/MS Method

The new breakthrough cystic fibrosis (CF) drug combination of ivacaftor (IVA), tezacaftor (TEZ), and elexacaftor (ELX), namely "caftor" drugs, directly modulates the activity and trafficking of the defective CF transmembrane conductance regulator protein (CFTR) underlying the CF disease. The role of therapeutic drug monitoring (TDM) of caftor drugs in clinical settings has recently been established. The availability of reliable and robust analytical methods for the quantification of IVA, TEZ, and ELX is essential to support dose-concentration-effect studies. We have developed and validated a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the rapid and simultaneous quantification of IVA, TEZ, and ELX from the plasma of CF patients. The method was based on a rapid extraction protocol from 50 μL human plasma and separation on a reversed-phase C-18 HPLC column after the addition of deuterated internal standards. Accurate analyte quantification using multiple reaction monitoring (MRM) detection was then obtained using a Thermofisher Quantiva triple-quadrupole MS coupled to an Ultimate 3000 UHPLC. The method has been validated following international (EMA) guidelines for bioanalytical method validation and has been tested on plasma samples from 62 CF patients treated with the three-drug combination IVA/TEZ/ELX, marketed as Kaftrio® or Trikafta®, in steady-state condition. The assay was linear over wide concentration ranges (0.008-12 mg/L) in plasma for IVA, TEZ, and ELX, suitable for a broad range of plasma concentrations, and accurate and reproducible in the absence of matrix effects. The stability of analytes for at least 30 days at room temperature could allow for cost-effective shipment and storage. On the same day of sample collection, a sweat test was evaluated for 26 associated patients' samples, FEV1 (%) for 58, and BMI was calculated for 62. However, Spearman correlation showed no correlation between Cthrough plasma concentrations of analytes (IVA, TEZ, ELX) and sweat test, FEV1 (%), or BMI. Our method proved to be suitable for TDM and could be helpful in assessing dose-concentration-response correlations in larger studies.

Method development for the determination of seven ginsenosides in three Panax ginseng reference materials via liquid chromatography with tandem mass spectrometry.

A new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the analysis of ginsenosides in three Panax ginseng reference materials (RMs). Extraction procedures were optimized to recover neutral and malonyl-ginsenosides using a methanol-water extraction under basic conditions. Optimized mass fragmentation transitions were obtained for the development of a multiple reaction monitoring (MRM) detection method with electrospray ionization in negative and positive ion mode. Mass fraction values were determined for ginsenosides Rb1, Rb2, Rc, Rd, Re, Rf, and Rg1 in the three ginseng materials (rhizomes, extract, and an oral dosage form). Quantitation of these seven compounds was accomplished with 4-methylestradiol and SRM 3389 Ginsenoside Calibration Solution serving as an internal standard (IS) and calibration standards, respectively. Mass fraction values for the seven ginsenosides ranged from 1.27mg/g to 21.42mg/g, 3.25mg/g to 35.81mg/g, and 0.56mg/g to 2.51mg/g for SRM 3384, SRM 3385, and RM 8664, respectively.

Valproic acid determination by liquid chromatography coupled to mass spectrometry (LC-MS/MS) in whole blood for forensic purposes.

Valproic acid (VPA) is a well-known drug prescribed as anti-epileptic. It has a narrow therapeutic range and shows great individual differences in pharmacodynamics and pharmacokinetics. Consequently, the therapeutical drug monitoring (TDM) in patient's plasma is of crucial importance. Liquid chromatography coupled to mass spectrometry (LC-MS/MS) has gained importance in TDM applications for its features of sensitivity, selectivity and rapidity. However, in case of VPA, the LC-MS/MS selectivity could be hampered by the lack of a sufficient number of multiple reaction monitoring (MRM) transitions describing the molecule. In fact, the product ion scan of deprotonated molecules of VPA does not produce any ion and thus most LC-MS/MS methods are based on the detection of the unique MRM transition m/z 143➔143. In this way, the advantages of selectivity in LC-MS cannot be effectively exploited. In the present method, stable analyte adducts were exploited for the determination of VPA in blood. An Acquity HSS C18 column and mobile phases consisting of 5-mM ammonium formate and acetonitrile both added 0.1% formic acid were used. Source worked in negative acquisition mode and parameters were optimized to increase the adduct (m/z 189) and dimer (m/z 287) stability, and their fragmentation were used to increase the selectivity of MRM detection. The method has been validated according to the toxicological forensic guidelines and successfully applied to 10 real blood samples. Finally, the present method showed suitable for the rapid LC-MS/MS detection of VPA in whole blood, demonstrating the possibility to increase specificity by exploiting stable in-source adducts. This should be considered of utmost importance in the case of forensic applications.

A strategy for intelligent chemical profiling-guided precise quantitation of multi-components in traditional Chinese medicine formulae-QiangHuoShengShi decoction

Due to the tremendous clinical value, more and more Traditional Chinese Medicines (TCMs) and their formulae are attracted by world's attention. QiangHuoShengShi (QHSS) decoction is one of classic TCM formulae, which is clinically used for treating various rheumatic diseases. However, the phytochemical constituents of QHSS have rarely been reported. A simple, intelligent, and comprehensive strategy was developed to characterize the phytochemical-fingerprint and quantify the chemical-markers for precise quality evaluation of QHSS. Firstly, a new deep-learning assisted mass defect filter (MDF) method was built for rapid and accurate classification of mass spectrum (MS) ions acquired by ultra-high performance liquid chromatography quadrupole time of flight tandem mass spectrometry (UHPLC-Q-TOF/MS). Subsequently, herb species-specific chemical-category and characteristic identification were used for further characterization of multi-components. As the result, seven major types of compounds in QHSS were intelligently differentiated and 183 phytochemical compounds were tentatively identified. Finally, a sensitive scheduled multiple reaction monitoring (sMRM) detection method was applied to precisely quantify 37 target analytes in QHSS decoction. This integrated strategy would provide an alternative method for chemical-material basis study of more herbal medicine or natural products.

Fitness for purpose of stabilized stool samples for bile acid metabolite analyses

Biobanks and cohort studies are increasingly utilizing chemical stabilizers to collect and store stool samples for downstream DNA-based microbiome analyses. While stabilizers permit ambient-temperature collection and storage of samples for gut microbiome studies, the use of the same sample type for downstream metabolomics assays has not been explored. Microbiome-metabolomics analysis of fecal samples is increasingly getting attention to further elucidate the mechanisms by which the gut microbiota influences the host. In this study, we evaluated fitness-for-purpose of OMNIgene-GUT-collected stool samples for downstream metabolomics assays in the scope of fecal bile acids (BA) quantification. Biocrates Bile Acids Kit was used for the quantification of BA from eight healthy donors’ samples collected in (1) OMNIgene-GUT kit and (2) snap frozen in −80 °C in duplicates. A highly selective reversed phase LC–MS/MS analysis method in negative ion multiple reaction monitoring (MRM) detection mode was applied to determine the BA concentrations in each sample.Total fecal BA levels were detectable in OMNIgene-GUT-collected samples (range: 29.9–903.7 pmol/mg). Paired t-test confirmed that there was a significant difference in the total BAs between the OMNIgene-GUT and snap frozen samples (p < 0.05). Extractions from snap frozen samples resulted in higher concentrations of total BAs (range: 243.7–1136.2 pmol/mg). Qualitative differences between individual donors’ BA profiles were detectable using the two sample collection methods. No significant difference was found in the relative concentrations of primary (CA, CDCA) or secondary (DCA, LCA, UDCA) unconjugated BAs to the total BA concentrations in OMNIgene-GUT-collected samples as compared with the snap frozen samples (Wilcoxon-Mann–Whitney test, p > 0.05). Passing-Bablok method comparison and correlation analyis showed a high degree of correlation in the relative concentrations of CA, CDCA, DCA and LCA between OMNIgene-GUT and snap frozen samples. For these four bile acids, the two methods are comparable at an acceptability bias of 30%. We conclude that the OMNIgene-GUT-collected stool samples are fit-for-purpose for downstream fecal bile acids analysis.

Quantitative mass spectrometry imaging of drugs and metabolites: a multiplatform comparison

Mass spectrometry imaging (MSI) provides insight into the molecular distribution of a broad range of compounds and, therefore, is frequently applied in the pharmaceutical industry. Pharmacokinetic and toxicological studies deploy MSI to localize potential drugs and their metabolites in biological tissues but currently require other analytical tools to quantify these pharmaceutical compounds in the same tissues. Quantitative mass spectrometry imaging (Q-MSI) is a field with challenges due to the high biological variability in samples combined with the limited sample cleanup and separation strategies available prior to MSI. In consequence, more selectivity in MSI instruments is required. This can be provided by multiple reaction monitoring (MRM) which uses specific precursor ion-product ion transitions. This targeted approach is in particular suitable for pharmaceutical compounds because their molecular identity is known prior to analysis. In this work, we compared different analytical platforms to assess the performance of MRM detection compared to other MS instruments/MS modes used in a Q-MSI workflow for two drug candidates (A and B). Limit of detection (LOD), linearity, and precision and accuracy of high and low quality control (QC) samples were compared between MS instruments/modes. MRM mode on a triple quadrupole mass spectrometer (QqQ) provided the best overall performance with the following results for compounds A and B: LOD 35.5 and 2.5 μg/g tissue, R2 0.97 and 0.98 linearity, relative standard deviation QC <13.6%, and 97–112% accuracy. Other MS modes resulted in LOD 6.7–569.4 and 2.6–119.1 μg/g tissue, R2 0.86–0.98 and 0.86–0.98 linearity, relative standard deviation QC < 19.4 and < 37.5%, and 70–356% and 64–398% accuracy for drug candidates A and B, respectively. In addition, we propose an optimized 3D printed mimetic tissue model to increase the overall analytical throughput of our approach for large animal studies. The MRM imaging platform was applied as proof-of-principle for quantitative detection of drug candidates A and B in four dog livers and compared to LC-MS. The Q-MSI concentrations differed <3.5 times with the concentrations observed by LC-MS. Our presented MRM-based Q-MSI approach provides a more selective and high-throughput analytical platform due to MRM specificity combined with an optimized 3D printed mimetic tissue model.Graphical abstract

Novel UPLC-MS/MS Method for Standardization of Niazimicin Content in Edible Seeds and Leaves of Moringa Oleifera Lam.

Moringa oleifera (MO) is a highly nutritious plant, whose leaves and seed pods are consumed in Africa, Asia, sub-Himalayan regions and South America. A novel ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the standardization of the bioactive thiocarbamate compound from MO, niazimicin (NZ) in seeds and leaves, is developed, optimized and validated according to the International Conference on Harmonization (ICH) guidelines, using desipramine as the internal standard. Multiple reaction monitoring detection of transitions 358.05>106.86 and 266.38 > 193.04 with collision energy of 25V and 40V, respectively were used. A gradient was optimized at 35–55%B in 7 min, where mobile phase A is aqueous 0.1% formic acid and B is 0.1% formic acid in acetonitrile. The method proved to be linear in the range of 0.05–100 μg/mL, precise, robust and accurate, with LOD and LOQ of 0.02 and 0.05 μg/mL, respectively. MO seeds were found to contain double NZ content (620 mg% ±3.2%) compared to leaves, and the methylene chloride fraction of seeds comprised triple the amount in ethyl acetate fraction (450 mg% ± 2.4%). Results emphasize that seeds of MO are a much richer source for NZ than the most commonly edible and marketed leaves extracts. The reported method can be used for standardization and quality control of the seeds and leaves NZ content.

Direct analysis in real time-mass spectrometry for rapid quantification of five anti-arrhythmic drugs in human serum: application to therapeutic drug monitoring

Therapeutic drug monitoring (TDM) is necessary for the optimal administration of anti-arrhythmic drugs in the treatment of heart arrhythmia. The present study aimed to develop and validate a direct analysis in real time tandem mass spectrometry (DART–MS/MS) method for the rapid and simultaneous determination of five anti-arrhythmic drugs (metoprolol, diltiazem, amiodarone, propafenone, and verapamil) and one metabolite (5-hydroxy(OH)-propafenone) in human serum. After the addition of isotope-labeled internal standards and protein precipitation with acetonitrile, anti-arrhythmic drugs were ionized by DART in positive mode followed by multiple reaction monitoring (MRM) detection. The use of DART–MS/MS avoided the need for chromatographic separation and allowed rapid and ultrahigh throughput analysis of anti-arrhythmic drugs in a total run time of 30 s per sample. The DART–MS/MS method yielded satisfactory linearity (R2 ≥ 0.9906), accuracy (86.1–109.9%), and precision (≤ 14.3%) with minimal effect of biological matrixes. The method was successfully applied to analyzing 30 clinical TDM samples. The relative error (RE) of the concentrations obtained by DART–MS/MS and liquid chromatography-tandem mass spectrometry (LC–MS/MS) was within ± 13%. This work highlights the potential usefulness of DART for the rapid quantitative analysis of anti-arrhythmic drugs in human serum and gives rapid feedback in the clinical TDM practices.

N-glycolyl chondroitin synthesis using metabolically engineered E. coli

N-glycolyl chondroitin (Gc-CN) is a metabolite of N-glycolylneuraminic acid (Neu5Gc), a sialic acid that is commonly found in mammals, but not humans. Humans can incorporate exogenous Neu5Gc into their tissues from eating red meat. Neu5Gc cannot be biosynthesized by humans due to an evolutionary mutation and has been implicated in causing inflammation causing human diseases, such as cancer. The study Neu5Gc is important in evolutionary biology and the development of potential cancer biomarkers. Unfortunately, there are several limitations to detecting Neu5Gc. The elimination of Neu5Gc involves a degradative pathway leading to the incorporation of N-glycolyl groups into glycosaminoglycans (GAGs), such as Gc-CN. Gc-CN has been found in humans and in animals including mice, lamb and chimpanzees. Here, we present the biosynthesis of Gc-CN in bacteria by feeding chemically synthesized N-glycolylglucosamine to Escherichia coli. A metabolically engineered strain of E. coli K4, fed with glucose supplemented with GlcNGc, converted it to N-glycolylgalactosamine (GalNGc) that could then be utilized as a substrate in the chondroitin biosynthetic pathway. The final product, Gc-CN was converted to disaccharides using chondroitin lyase ABC and analyzed by liquid chromatography–tandem mass spectrometry with multiple reaction monitoring detection. This analysis showed the incorporation of GalNGc into the backbone of the chondroitin oligosaccharide.

18f]-(2S,4R)-4-Fluoroglutamine As a New Positron Emission Tomography Tracer in Multiple Myeloma

High glycolitic activity of multiple myeloma (MM) cells is the rationale for the use of Positron Emission Tomography (PET) with 18F-fluorodeoxyglucose ([18F]FDG) to detect both medullary and extramedullary disease. However, FDG-PET has some limitations, since there is a good portion of MM patients who are false-negative. Besides enhanced glycolysis, glutamine (Gln) addiction has been recently described as a metabolic feature of MM by our group. To sustain high Gln demand, MM cells increase the expression of several Gln transporters (ASCT2, SNAT1, LAT1) and are endowed with fast Gln uptake. Yet, at variance with other Gln-addicted cancers, the possible exploitation of Gln as a PET tracer in MM has never been assessed and was investigated in this study. To this purpose, we have firstly synthesized enantiopure (2S,4R)-4-Fluoroglutamine (4-FGln) and validated it as a Gln analogue in human MM cell lines (RPMI8226 and JJN3) comparing its uptake with that of 3H-labelled Gln. The intracellular levels of 4-FGln were determined by HPLC-MS/MS employing a HILIC gradient separation and multiple reaction monitoring (MRM) detection. Both Gln and 4-FGln were actively accumulated by MM cells and exhibited a strong reciprocal competition, pointing to shared transporters. Inhibition analysis revealed that ASCT2 was the major entry route of both compounds, with minor contributions from the other transporters. However, compared with Gln, 4-FGln exhibited higher affinity for both ASCT2 and LAT1 transporters. On the basis of these results, we then tested [18F]4-FGln uptake for MM detection by Positron Emission Tomography (PET) in two different in vivo murine models. Firstly, to investigate sensitivity of human MM to [18F]4-FGln in vivo, JJN3 cells were subcutaneously injected in immunodeficient NSG mice In this xenograft model, [18F]4-FGln- and[18F]FDG-PET scans were performed after plasmacytomas became palpable and repeated after one week. All the tumours were positive for [18F]FDG and displayed [18F]4-FGln uptake with Standard Uptake Values (SUV) of 1.21±1.9 and 0.99±0.07 after 2 weeks, respectively. Thereafter, the effect of bortezomib (BOR) was investigated to evaluate the potential use of [18F]4-FGln to monitor anti-MM treatment. Ten NGS mice were injected with JJN3 cells and, after 14 days, treated twice weekly with BOR, 1mg/kg, or vehicle for two weeks. PET scans were performed before and after 5 and 12 days of BOR treatment. As expected, BOR reduced tumour size as compared to vehicle. At the first post-BOR PET scan, [18F]4-FGln (SUV mean: pre 0.85±0.31; post 0.45±0.10, P&lt;0.05), but not [18F]FDG (SUV mean: pre 0.97±0.38, post 0.75±0.14) was already significantly reduced: [18F]FDG and [18F]4-FGln uptake was reduced of 22 and 45% respectively. With both radiotracers, BOR treated animals displayed SUV mean values significantly lower than those of vehicle treated animals at post treatment PET (SUV means [18F ]FDG: BOR 0.75±0.14; vehicle 1.27±0.34, P&lt;0.05; SUV mean [18F]4-FGln: BOR 0.45±0.10 ; vehicle: 0.73±0.18 ; P &lt;0.05). Thereafter, to mimic BOR-resistant MM in a syngeneic mouse model, C57BL/6 mice were injected intravenously with Vk12598 cells obtained from transgenic Vk*MYC mice repeatedly treated with sub-optimal doses of BOR. Upon injection into C57BL/6 mice, Vk12598 cells colonize the BM without lytic lesions and extensively colonize the spleen generating an aggressive MM that brings animals to death within five weeks. PET scans were performed with [18F]4-FGln and [18F]FDG before Vk*MYC MM cells injection and after three, four and five weeks. Blood samples for M-spike evaluation were obtained in parallel. Four weeks after MM cells injection a significant increase of both [18F]4-FGln and [18F]FDG uptake was detected in spleens (SUV mean: 1.14±0.23, P=0.018; 0.94±0.24, P= 0.005). In both MM models, the volume of distribution of [18F]4-F-Gln did not overlap that of [18F]FDG. In conclusion, our data indicate that [18F]-(2S,4R)-4-Fluoroglutamine is a new potential PET tracer in pre-clinical MM models especially of extramedullary disease, either in a BOR-sensitive or in a BOR-resistant context, supporting the exploitation of Gln addiction for diagnostic purposes in MM patients. Disclosures Giuliani: Janssen: Research Funding.