Rapid quantitative analysis of methylphenidate and ritalinic acid in oral fluid by liquid chromatography triple quadrupole mass spectrometry (LC-QqQ-MS)

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Carmen T. Mulet, Luis E. Arroyo-Mora, Lorena A. Leon, Elizabeth Gnagy, Anthony P. DeCaprio
Methylphenidate (MPH), which is metabolized into ritalinic acid (RA), is an amphetamine derivative largely used in the treatment of attention-deficit hyperactivity disorder, a neurological condition commonly diagnosed in early childhood. Ensuring that patients comply with clinical treatment is crucial and compliance is generally monitored in blood or urine specimens which, especially in the case of children, can be challenging to obtain on a repetitive basis. Here we report validation of a specific, non-invasive, and rapid dilute-and-shoot analytical method for the detection and quantitation of MPH and RA in oral fluid (OF). The method is based on liquid chromatography coupled to triple quadrupole MS with electrospray ionization utilizing dynamic MRM mode. Subject OF specimens were collected using a Quantisal™ device, processed, and diluted for analysis with seven-point quadratic calibration curves (weighting of 1/x) using MPH-d9 and (±)-threo-RA-d10 as internal standards. QC samples and diluted specimens showed intra- and inter-day bias and imprecision values no greater than ±12%. The LOD and LOQ for MPH were 0.1 and 0.5 ng/mL, respectively, and 0.2 ng/mL and 0.5 ng/mL for RA, respectively, indicating the validity of the method for identification and confirmation at low concentrations. Selectivity was specific for the analytes of interest and matrix effects were minimized through the use of internal standard based quantitation.

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Carmen T. Mulet, Luis E. Arroyo-Mora, Lorena A. Leon, Elizabeth Gnagy, Anthony P. DeCaprio

Methylphenidate (MPH), which is metabolized into ritalinic acid (RA), is an amphetamine derivative largely used in the treatment of attention-deficit hyperactivity disorder, a neurological condition commonly diagnosed in early childhood. Ensuring that patients comply with clinical treatment is crucial and compliance is generally monitored in blood or urine specimens which, especially in the case of children, can be challenging to obtain on a repetitive basis. Here we report validation of a specific, non-invasive, and rapid dilute-and-shoot analytical method for the detection and quantitation of MPH and RA in oral fluid (OF). The method is based on liquid chromatography coupled to triple quadrupole MS with electrospray ionization utilizing dynamic MRM mode. Subject OF specimens were collected using a Quantisal™ device, processed, and diluted for analysis with seven-point quadratic calibration curves (weighting of 1/x) using MPH-d 9 and (±)-threo-RA-d 10 as internal standards. QC samples and diluted specimens showed intra- and inter-day bias and imprecision values no greater than ±12%. The LOD and LOQ for MPH were 0.1 and 0.5 ng/mL, respectively, and 0.2 ng/mL and 0.5 ng/mL for RA, respectively, indicating the validity of the method for identification and confirmation at low concentrations. Selectivity was specific for the analytes of interest and matrix effects were minimized through the use of internal standard based quantitation.





MS-based quantification of RhoA/B and RhoC ADP-ribosylation

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Anke Schröder, Anastasia Benski, Anne Oltmanns, Ingo Just, Astrid Rohrbeck, Andreas Pich
Mono ADP-ribosylation is a common characteristic of bacterial toxins resulting to aberrant activation or inactivation of target proteins. The C3 exoenzyme of Clostridium botulinum (C3bot) ADP-ribosylates the small GTPases RhoA, RhoB and RhoC, leading to inactivation of these important regulators and impaired down-stream signaling. Quantification of ADP-ribosylation using gel migration assays, antibodies, and radioactivity-based methods are limited. Therefore a novel LC-MS-based method to specifically determine and quantify ADP-ribosylation of Rho GTPases was established. A heavy labeled protein standard that contained ADP-ribosylation specific peptides in similar amounts in ADP ribosylated and non ADP ribosylated form was used for relative quantification in vivo. In a proof of principle experiment HT22 cells were treated with C3bot and the kinetics of RhoA/B and RhoC ADP-ribosylation were determined in vivo.

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Anke Schröder, Anastasia Benski, Anne Oltmanns, Ingo Just, Astrid Rohrbeck, Andreas Pich

Mono ADP-ribosylation is a common characteristic of bacterial toxins resulting to aberrant activation or inactivation of target proteins. The C3 exoenzyme of Clostridium botulinum (C3bot) ADP-ribosylates the small GTPases RhoA, RhoB and RhoC, leading to inactivation of these important regulators and impaired down-stream signaling. Quantification of ADP-ribosylation using gel migration assays, antibodies, and radioactivity-based methods are limited. Therefore a novel LC-MS-based method to specifically determine and quantify ADP-ribosylation of Rho GTPases was established. A heavy labeled protein standard that contained ADP-ribosylation specific peptides in similar amounts in ADP ribosylated and non ADP ribosylated form was used for relative quantification in vivo. In a proof of principle experiment HT22 cells were treated with C3bot and the kinetics of RhoA/B and RhoC ADP-ribosylation were determined in vivo.





Separation of stereoisomers of 7-oxa-bicyclo[2.2.1]heptene sulfonate (OBHS), a Selective Estrogen Receptor Modulator (SERM), via chiral stationary phases using SFC/UV and SFC/MS

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Penagaluri Balasubramanyam, Mehdi Ashraf-Khorassani, Jatinder S. Josan
The enantiomeric separation of a racemate of 7-oxa-bicyclo[2.2.1]heptene sulfonate (OBHS) derivatives, a Selective Estrogen Receptor Modulator (SERM), was obtained using supercritical fluid chromatography in tandem with UV and mass spectrometry (SFC/UV and SFC/MS, respectively). Supercritical CO2 modified with methanol or isopropyl alcohol was used with isopropylamine (IPAm), trimethylamine (TEA), or trifluoroacetic acid (TFA) as an additive to obtain the enantiomers separations. Both Chiralpak IC and IA were evaluated for the separation of enantiomers. Results showed enantiomers separation can be achieved in less than 5 min with a resolution greater than 1 and 0.9, respectively, for the different OBHS derivatives (compounds A and B) using supercritical CO2 modified with 40% isopropyl alcohol containing 0.25% IPAm and IC column applying isocratic conditions. Similar conditions were used with the semi-preparative Chiralpak IC column to isolate more than 50 mg of each enantiomer. SFC/MS and SFC/UV results showed pure enantiomers were isolated. Method development via SFC was much simpler than those reported in the literature using HPLC.

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Penagaluri Balasubramanyam, Mehdi Ashraf-Khorassani, Jatinder S. Josan

The enantiomeric separation of a racemate of 7-oxa-bicyclo[2.2.1]heptene sulfonate (OBHS) derivatives, a Selective Estrogen Receptor Modulator (SERM), was obtained using supercritical fluid chromatography in tandem with UV and mass spectrometry (SFC/UV and SFC/MS, respectively). Supercritical CO2 modified with methanol or isopropyl alcohol was used with isopropylamine (IPAm), trimethylamine (TEA), or trifluoroacetic acid (TFA) as an additive to obtain the enantiomers separations. Both Chiralpak IC and IA were evaluated for the separation of enantiomers. Results showed enantiomers separation can be achieved in less than 5 min with a resolution greater than 1 and 0.9, respectively, for the different OBHS derivatives (compounds A and B) using supercritical CO2 modified with 40% isopropyl alcohol containing 0.25% IPAm and IC column applying isocratic conditions. Similar conditions were used with the semi-preparative Chiralpak IC column to isolate more than 50 mg of each enantiomer. SFC/MS and SFC/UV results showed pure enantiomers were isolated. Method development via SFC was much simpler than those reported in the literature using HPLC.





Development of a UPLC-MS/MS method for quantitation of metronidazole and 2-hydroxy metronidazole in human plasma and its application to a pharmacokinetic study

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Stephani L. Stancil, Leon van Haandel, Susan Abdel-Rahman, Robin E. Pearce
An ultra-performance liquid-chromatography mass-spectrometry (UPLC-MS/MS) method for simultaneous quantitation of metronidazole and 2-hydroxymetronidazole in human plasma was developed and validated. Metronidazole and 2-hydroxymetronidazole were extracted from a small volume of human plasma (10 μL) by hydrophilic lipophilic balanced solid phase extraction on 96-well μ-elution plates. Chromatographic separation of analytes was achieved on an Acquity UPLC BEH C18 column (1.7 μm, 2.1 × 100 mm) using gradient elution with a blend of 0.1% formic acid in water and 0.1% formic acid in methanol at a flow rate of 0.25 mL/min. Mass spectrometric detection was achieved using multiple reaction monitoring (MRM) in positive-ion electrospray-ionization (ESI) mode. Ion transitions were optimized at m/z 171.85->127.9 for metronidazole and m/z 187.9->125.9 for 2-hydroxymetronidazole. The assay was linear for both analytes over the concentration range of 0.1–300 μM; intra- and inter-assay precisions and accuracies were <13%. Recoveries for metronidazole and 2-hydroxymetronidazole ranged from 88 to 99% and 78 to 86%, respectively. Matrix effects for metronidazole and 2-hydroxymetronidazole in plasma ranged from 102 to 105% and 99 to 106%, respectively. The method was successfully applied to determine metronidazole and 2-hydroxymetronidazole plasma concentrations in a pharmacokinetic study conducted in adults administered an oral dose of 500 mg metronidazole. Pharmacokinetic parameters were comparable to previously reported values. By design, this method is amenable to high sample throughput and has the potential to be automated.

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Stephani L. Stancil, Leon van Haandel, Susan Abdel-Rahman, Robin E. Pearce

An ultra-performance liquid-chromatography mass-spectrometry (UPLC-MS/MS) method for simultaneous quantitation of metronidazole and 2-hydroxymetronidazole in human plasma was developed and validated. Metronidazole and 2-hydroxymetronidazole were extracted from a small volume of human plasma (10 μL) by hydrophilic lipophilic balanced solid phase extraction on 96-well μ-elution plates. Chromatographic separation of analytes was achieved on an Acquity UPLC BEH C18 column (1.7 μm, 2.1 × 100 mm) using gradient elution with a blend of 0.1% formic acid in water and 0.1% formic acid in methanol at a flow rate of 0.25 mL/min. Mass spectrometric detection was achieved using multiple reaction monitoring (MRM) in positive-ion electrospray-ionization (ESI) mode. Ion transitions were optimized at m/z 171.85->127.9 for metronidazole and m/z 187.9->125.9 for 2-hydroxymetronidazole. The assay was linear for both analytes over the concentration range of 0.1–300 μM; intra- and inter-assay precisions and accuracies were <13%. Recoveries for metronidazole and 2-hydroxymetronidazole ranged from 88 to 99% and 78 to 86%, respectively. Matrix effects for metronidazole and 2-hydroxymetronidazole in plasma ranged from 102 to 105% and 99 to 106%, respectively. The method was successfully applied to determine metronidazole and 2-hydroxymetronidazole plasma concentrations in a pharmacokinetic study conducted in adults administered an oral dose of 500 mg metronidazole. Pharmacokinetic parameters were comparable to previously reported values. By design, this method is amenable to high sample throughput and has the potential to be automated.





High-throughput lipidomics characterize key lipid molecules as potential therapeutic targets of Kaixinsan protects against Alzheimer’s disease in APP/PS1 transgenic mice

Publication date: 15 August 2018 Source:Journal of Chromatography B, Volume 1092 Author(s): Hong-Lei Gao, Ai-Hua Zhang, Jing-Bo Yu, Hui Sun, Ling Kong, Xiang-Qian Wang, Guang-li Yan, Liang Liu, Xi-Jun Wang Alzheimer’s…

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Hong-Lei Gao, Ai-Hua Zhang, Jing-Bo Yu, Hui Sun, Ling Kong, Xiang-Qian Wang, Guang-li Yan, Liang Liu, Xi-Jun Wang

Alzheimer's disease (AD) is still a major problem nowadays. Under the circumstance of many chemical drugs have poor effects on AD, traditional Chinese medicine has become a hot spot for us due to its multi-target and multi-path advantages. To explore the potential therapeutic targets of Kaixinsan (KXS) protects against AD in APP/PS1 transgenic mice model. All mice were divided into three groups: control group, model group and KXS group. Orally given KXS from two month old, and the control and model groups were given the same dose of distilled water. We collected all mice's serum samples at the 12th month age to determine the lipid markers of AD by compare with the model and control groups in full-scan analysis based on high-throughput serum lipidomics technology. Then we found the lipid molecules called back by KXS from the KXS protects against AD. Compared with the control group, the metabolic profile of the model mice was obviously disordered, and we identified 16 lipid-related biomarkers associated with AD. After KXS treatment, the metabolic profiles of these disorders tended to recover compared with the model group. And we identified eight key lipid molecules, of which four had statistical significance. We found that the main perturbation pathways related to AD were linoleic acid metabolism, arachidonic acid metabolism and sphingolipid metabolism. All these metabolic pathways showed different degrees of rotation after KXS administration. Through the pathways analysis, we found 4 lipids molecules with significant differences, which could be used as new targets for the treatment of AD.





Facile quantitation of free thiols in a recombinant monoclonal antibody by reversed-phase high performance liquid chromatography with hydrophobicity-tailored thiol derivatization

Publication date: 15 August 2018 Source:Journal of Chromatography B, Volume 1092 Author(s): Leslie Welch, Xiao Dong, Daniel Hewitt, Michelle Irwin, Luke McCarty, Christina Tsai, Tomasz Baginski Free thiol content, and its…

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Leslie Welch, Xiao Dong, Daniel Hewitt, Michelle Irwin, Luke McCarty, Christina Tsai, Tomasz Baginski

Free thiol content, and its consistency, is one of the product quality attributes of interest during technical development of manufactured recombinant monoclonal antibodies (mAbs). We describe a new, mid/high-throughput reversed-phase-high performance liquid chromatography (RP-HPLC) method coupled with derivatization of free thiols, for the determination of total free thiol content in an E. coli-expressed therapeutic monovalent monoclonal antibody mAb1. Initial selection of the derivatization reagent used an hydrophobicity-tailored approach. Maleimide-based thiol-reactive reagents with varying degrees of hydrophobicity were assessed to identify and select one that provided adequate chromatographic resolution and robust quantitation of free thiol-containing mAb1 forms. The method relies on covalent derivatization of free thiols in denatured mAb1 with N-tert-butylmaleimide (NtBM) label, followed by RP-HPLC separation with UV-based quantitation of native (disulfide containing) and labeled (free thiol containing) forms. The method demonstrated good specificity, precision, linearity, accuracy and robustness. Accuracy of the method, for samples with a wide range of free thiol content, was demonstrated using admixtures as well as by comparison to an orthogonal LC-MS peptide mapping method with isotope tagging of free thiols. The developed method has a facile workflow which fits well into both R&D characterization and quality control (QC) testing environments. The hydrophobicity-tailored approach to the selection of free thiol derivatization reagent is easily applied to the rapid development of free thiol quantitation methods for full-length recombinant antibodies.





Preconcentration and GC–MS determination of caffeine in tea and coffee using homogeneous liquid–liquid microextraction based on solvents volume ratio alteration

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Tooraj Amini, Payman Hashemi
A simple, fast and green homogeneous liquid–liquid microextraction (HLLME) method based on solvents volume ratio alteration (SVRA) combined with gas chromatography–mass spectrometry (GC–MS) was developed for the preconcentration and determination of caffeine in tea and coffee samples. In the proposed HLLME-SVRA method, the primary extraction from solid samples was achieved by a 2:1 ethanol-water mixture. A micro-volume of dichloromethane (DCM) formed a homogeneous solvent with this mixture after choosing an appropriate volume ratio between the three solvents. After vigorous shaking, an extra volume of water was added that resulted in phase separation due to the solvents volume ratio alteration. As a result, complete extraction of caffeine was achieved after centrifugation. The sedimented dichloromethane phase was then injected into GC–MS for the analysis. The influence of a number of parameters influencing the efficiency of the extraction was investigated and optimized. Under the optimal conditions, an enrichment factor of 11, a limit of detection of 0.05 μg mL−1 and a limit of quantification of 0.16 μg mL−1 were obtained for caffeine. A linear dynamic range of 0.16 to 50 μg mL−1 and a determination coefficient (R2) of 0.9980 were achieved. The precision of the method, expressed as relative standard deviation, was 4.8% for six replicated measurements. The method was successfully applied to the determination of caffeine in tea and coffee samples.

Graphical abstract

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Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Tooraj Amini, Payman Hashemi

A simple, fast and green homogeneous liquid–liquid microextraction (HLLME) method based on solvents volume ratio alteration (SVRA) combined with gas chromatography–mass spectrometry (GC–MS) was developed for the preconcentration and determination of caffeine in tea and coffee samples. In the proposed HLLME-SVRA method, the primary extraction from solid samples was achieved by a 2:1 ethanol-water mixture. A micro-volume of dichloromethane (DCM) formed a homogeneous solvent with this mixture after choosing an appropriate volume ratio between the three solvents. After vigorous shaking, an extra volume of water was added that resulted in phase separation due to the solvents volume ratio alteration. As a result, complete extraction of caffeine was achieved after centrifugation. The sedimented dichloromethane phase was then injected into GC–MS for the analysis. The influence of a number of parameters influencing the efficiency of the extraction was investigated and optimized. Under the optimal conditions, an enrichment factor of 11, a limit of detection of 0.05 μg mL−1 and a limit of quantification of 0.16 μg mL−1 were obtained for caffeine. A linear dynamic range of 0.16 to 50 μg mL−1 and a determination coefficient (R2) of 0.9980 were achieved. The precision of the method, expressed as relative standard deviation, was 4.8% for six replicated measurements. The method was successfully applied to the determination of caffeine in tea and coffee samples.

Graphical abstract

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Qualitative and quantitative drug residue analyses: Chlortetracycline in white-tailed deer (Odocoileus virginianus) and supermarket meat by liquid chromatography tandem-mass spectrometry

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Shanoy C. Anderson, Seenivasan Subbiah, Angella Gentles, Darryll Oliver, Paul Stonum, Tiffanie A. Brooks, Ernest E. Smith
Chlortetracycline is (CTC) is a tetracycline antibiotic which is being in the white-tailed deer industry to improve production and animal health. In this paper, we present a method for determining chlortetracycline residues in edible white-tailed deer tissues, using liquid chromatography with heated electrospray ionization and mass spectrometry detection.The procedure involved extraction with EDTA-McIlvaine buffer at pH 4.0, followed by solid-phase extraction cleanup using a hydrophilic-lipophilic balance (HLB) cartridge. The liquid chromatography analysis was performed with heated electrospray ionization and mass spectrometry detection. The limit of quantification for the method was 2.7 ng/g and limit of detection was 0.8 ng/g. The recovery values were >78.5% for muscle, 65.1% for kidney, 63.1% for liver. Mean tissue residue concentration of chlortetracycline and it’s epimer, 4-epi chlortetracycline (4-epi-CTC) at 10-day withdrawal period for kidney, liver, muscle was 122.8, 44.7 and 26.7 ng/g, respectively. Chlortetracycline tissue residue concentration at 45-day withdrawal period for kidney, liver, muscle was 19.2, 28.9 and 10.7 ng/g, respectively. Mean tissue concentration of CTC was less than the established maximum residual limit (MRL) values for bovine tissues. We have validated and successfully applied this method in the qualitative and quantification of chlortetracycline in white-tailed deer tissue samples.

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Shanoy C. Anderson, Seenivasan Subbiah, Angella Gentles, Darryll Oliver, Paul Stonum, Tiffanie A. Brooks, Ernest E. Smith

Chlortetracycline is (CTC) is a tetracycline antibiotic which is being in the white-tailed deer industry to improve production and animal health. In this paper, we present a method for determining chlortetracycline residues in edible white-tailed deer tissues, using liquid chromatography with heated electrospray ionization and mass spectrometry detection. The procedure involved extraction with EDTA-McIlvaine buffer at pH 4.0, followed by solid-phase extraction cleanup using a hydrophilic-lipophilic balance (HLB) cartridge. The liquid chromatography analysis was performed with heated electrospray ionization and mass spectrometry detection. The limit of quantification for the method was 2.7 ng/g and limit of detection was 0.8 ng/g. The recovery values were >78.5% for muscle, 65.1% for kidney, 63.1% for liver. Mean tissue residue concentration of chlortetracycline and it's epimer, 4-epi chlortetracycline (4-epi-CTC) at 10-day withdrawal period for kidney, liver, muscle was 122.8, 44.7 and 26.7 ng/g, respectively. Chlortetracycline tissue residue concentration at 45-day withdrawal period for kidney, liver, muscle was 19.2, 28.9 and 10.7 ng/g, respectively. Mean tissue concentration of CTC was less than the established maximum residual limit (MRL) values for bovine tissues. We have validated and successfully applied this method in the qualitative and quantification of chlortetracycline in white-tailed deer tissue samples.





Simultaneous quantification of 33 active components in Notopterygii Rhizoma et Radix using ultra high performance liquid chromatography with tandem mass spectrometry

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Xiu-Wen Wu, You-Bo Zhang, Lei Zhang, Xiu-Wei Yang
A method of ultra high performance liquid chromatography with tandem mass spectrometry was developed for the simultaneous quantification of 33 active components including 26 coumarins and 7 phenolic acid esters in Notopterygii Rhizoma et Radix (NRR). Chromatographic separation was achieved on a Kinetex® C18 column (100 mm × 2.1 mm i.d.; 2.6 μm) with a gradient elution in 18 min. Electrospray ionization tandem mass spectrometric detection was conducted in the positive and negative ionization modes with multiple reaction monitoring. All of 33 analytes showed good linearity (R2 ≥ 0.9919) within the test range. The relative standard deviations of the precision, repeatability and stability were not exceeding 4.97%, and the recoveries were in the range of 85.37%–115.00%. The matrix effect on the response of target analyte was not obvious. The validated method was successfully applied to quantify the 33 components in ten batches of NRR samples. Quantitative results showed the coumarins and phenolic acid esters with large difference in level of content in the herb samples. Furthermore, hierarchical cluster analysis and principal component analysis were applied to classify and discriminate these samples. The variations of isoimperatorin, notopterol, bergamottin, nodakenin, phenethylferulate were suggested as important indicators of NRR quality. This work may serve for quality identification and comprehensive evaluation of NRR.

Graphical abstract

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Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Xiu-Wen Wu, You-Bo Zhang, Lei Zhang, Xiu-Wei Yang

A method of ultra high performance liquid chromatography with tandem mass spectrometry was developed for the simultaneous quantification of 33 active components including 26 coumarins and 7 phenolic acid esters in Notopterygii Rhizoma et Radix (NRR). Chromatographic separation was achieved on a Kinetex® C18 column (100 mm × 2.1 mm i.d.; 2.6 μm) with a gradient elution in 18 min. Electrospray ionization tandem mass spectrometric detection was conducted in the positive and negative ionization modes with multiple reaction monitoring. All of 33 analytes showed good linearity (R2 ≥ 0.9919) within the test range. The relative standard deviations of the precision, repeatability and stability were not exceeding 4.97%, and the recoveries were in the range of 85.37%–115.00%. The matrix effect on the response of target analyte was not obvious. The validated method was successfully applied to quantify the 33 components in ten batches of NRR samples. Quantitative results showed the coumarins and phenolic acid esters with large difference in level of content in the herb samples. Furthermore, hierarchical cluster analysis and principal component analysis were applied to classify and discriminate these samples. The variations of isoimperatorin, notopterol, bergamottin, nodakenin, phenethylferulate were suggested as important indicators of NRR quality. This work may serve for quality identification and comprehensive evaluation of NRR.

Graphical abstract

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Sample treatment optimization for fish stool metabolomics

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Takeshi Hano, Mana Ito, Katsutoshi Ito, Motoharu Uchida
Gut microbiota play an essential role in an organism’s health. The fecal metabolite profiling content reflects these microbiota-mediated physiological changes in various organisms, including fish. Therefore, metabolomics analysis of fish feces should provide insight into the dynamics linking physiology and gut microbiota. However, metabolites are often unstable in aquatic environments, making fecal metabolites difficult to examine in fish. In this study, a novel method using gas chromatography–mass spectrometry (GC–MS) was developed and optimized for the preparation of metabolomics samples from the feces of the marine fish, red sea bream (Pagrus major). The preparation methodology was optimized, focusing on rinsing frequency and rinsing solvent. Feces (collected within 4 h of excretion) were rinsed three times with sterilized 2.5% NaCl solution or 3.0% artificial seawater (ASW). Among the 86 metabolites identified in the NaCl-rinsed samples, 57 showed superior recovery to that in ASW-rinsed samples, indicating that NaCl is a better rinsing solvent, particularly for amino acids, organic acids, and fatty acids. To evaluate rinsing frequency, fecal samples were rinsed with NaCl solution 0, 1, 3, or 5 times. The results indicate that three or more rinses enabled robust and stable detection of metabolites encapsulated within the solid fecal residue. Furthermore, these data suggest that rinsing is unnecessary when studying sugars, amino acids, and sterols, again highlighting the need for appropriate rinsing solvent and frequency. This study provides further insight into the use of fecal samples to evaluate and promote fish health during farming and supports the application of this and similar analyses to study the effects of environmental fluctuations and/or contamination.

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Takeshi Hano, Mana Ito, Katsutoshi Ito, Motoharu Uchida

Gut microbiota play an essential role in an organism's health. The fecal metabolite profiling content reflects these microbiota-mediated physiological changes in various organisms, including fish. Therefore, metabolomics analysis of fish feces should provide insight into the dynamics linking physiology and gut microbiota. However, metabolites are often unstable in aquatic environments, making fecal metabolites difficult to examine in fish. In this study, a novel method using gas chromatography–mass spectrometry (GC–MS) was developed and optimized for the preparation of metabolomics samples from the feces of the marine fish, red sea bream (Pagrus major). The preparation methodology was optimized, focusing on rinsing frequency and rinsing solvent. Feces (collected within 4 h of excretion) were rinsed three times with sterilized 2.5% NaCl solution or 3.0% artificial seawater (ASW). Among the 86 metabolites identified in the NaCl-rinsed samples, 57 showed superior recovery to that in ASW-rinsed samples, indicating that NaCl is a better rinsing solvent, particularly for amino acids, organic acids, and fatty acids. To evaluate rinsing frequency, fecal samples were rinsed with NaCl solution 0, 1, 3, or 5 times. The results indicate that three or more rinses enabled robust and stable detection of metabolites encapsulated within the solid fecal residue. Furthermore, these data suggest that rinsing is unnecessary when studying sugars, amino acids, and sterols, again highlighting the need for appropriate rinsing solvent and frequency. This study provides further insight into the use of fecal samples to evaluate and promote fish health during farming and supports the application of this and similar analyses to study the effects of environmental fluctuations and/or contamination.





Effect of seaweed supplementation on tocopherol concentrations in bovine milk using dispersive liquid-liquid microextraction

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Andrew Quigley, Siobhán W. Walsh, Eva Hayes, Damian Connolly, Wayne Cummins
A dispersive liquid-liquid microextraction (DLLME) method, combined with HPLC-UV detection, was developed for the extraction and preconcentration of δ-tocopherol from bovine milk. This method was used to study the effect of supplementing cow feed with the seaweed Ascophyllum nodosum on vitamin content in milk. The optimal experimental conditions were determined: 200 μL of chloroform (extraction solvent), 1.0 mL of ethanol (dispersive solvent), 5 mL of water (aqueous phase). Under these optimal conditions the DLLME method provided linearity in the range 0.01 μg/mL to 8 μg/mL with R2 values of 0.998. Limit of detection (LOD) was 0.01 μg/mL, while the enrichment factor was 89. Cow feed that was supplemented with Ascophyllum nodosum was shown to increase δ-tocopherol levels from 3.82 μg/mL to 5.96 μg/mL.

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Andrew Quigley, Siobhán W. Walsh, Eva Hayes, Damian Connolly, Wayne Cummins

A dispersive liquid-liquid microextraction (DLLME) method, combined with HPLC-UV detection, was developed for the extraction and preconcentration of δ-tocopherol from bovine milk. This method was used to study the effect of supplementing cow feed with the seaweed Ascophyllum nodosum on vitamin content in milk. The optimal experimental conditions were determined: 200 μL of chloroform (extraction solvent), 1.0 mL of ethanol (dispersive solvent), 5 mL of water (aqueous phase). Under these optimal conditions the DLLME method provided linearity in the range 0.01 μg/mL to 8 μg/mL with R2 values of 0.998. Limit of detection (LOD) was 0.01 μg/mL, while the enrichment factor was 89. Cow feed that was supplemented with Ascophyllum nodosum was shown to increase δ-tocopherol levels from 3.82 μg/mL to 5.96 μg/mL.





Searching for synergistic calcium antagonists and novel therapeutic regimens for coronary heart disease therapy from a Traditional Chinese Medicine, Suxiao Jiuxin Pill

Publication date: 15 August 2018 Source:Journal of Chromatography B, Volume 1092 Author(s): Wei Lei, Jianan Ni, Xueting Xia, Min Jiang, Gang Bai Coronary heart disease is a vital cause of morbidity and mortality worldwide, an…

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Wei Lei, Jianan Ni, Xueting Xia, Min Jiang, Gang Bai

Coronary heart disease is a vital cause of morbidity and mortality worldwide, and calcium channel blockers (CCBs) are important drugs that can be used to treat cardiovascular diseases. Suxiao Jiuxin Pill (SX), a traditional Chinese medicine, is widely used as an emergency drug for coronary heart disease therapy. However, understanding its potential mechanism in intracellular calcium concentration ([Ca2+]i) modulation remains a challenge. To identify the active pharmacological ingredients (APIs) and reveal a novel combination therapy for ameliorating cardiovascular diseases, the ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS) combined with a dual-luciferase reporter [Ca2+]i assay system was applied. Ligustrazine, ferulic acid, senkyunolide I, senkyunolide A and ligustilide were identified as potential calcium antagonists in SX, and the combination of ligustrazine and senkyunolide A showed synergetic calcium antagonistic activity. Additionally, the synergetic mechanism was further investigated by live-imaging analysis with the Ca2+ indicator fluo-4/AM by monitoring fluorescence changes. Our results indicated that ligustrazine can block voltage-operated Ca2+ channels (VDCCs) effectively and senkyunolide A can exert an inhibition effect mostly on ryanodine receptors (RYRs) and partly on VDCCs. Finally, an arterial ring assay showed that the combination of ligustrazine and senkyunolide A exerted a better vasodilatation function than using any components alone. In this study, we first revealed that a pair of natural APIs in combination acting on VDCCs and RYRs was more effective on vasodilatation by regulating [Ca2+]i.





A new high-performance thin-layer chromatographic method for determining bile salt hydrolase activity

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Nur Syakila Rohawi, Kalavathy Ramasamy, Snezana Agatonovic-Kustrin, Siong Meng Lim
A quantitative assay using high-performance thin-layer chromatography (HPTLC) was developed to investigate bile salt hydrolase (BSH) activity in Pediococcus pentosaceus LAB6 and Lactobacillus plantarum LAB12 probiotic bacteria isolated from Malaysian fermented food. Lactic acid bacteria (LAB) were cultured in de Man Rogosa and Sharpe (MRS) broth containing 1 mmol/L of sodium-based glyco- and tauro-conjugated bile salts for 24 h. The cultures were centrifuged and the resultant cell free supernatant was subjected to chromatographic separation on a HPTLC plate. Conjugated bile salts were quantified by densitometric scans at 550 nm and results were compared to digital image analysis of chromatographic plates after derivatisation with anisaldehyde/sulfuric acid. Standard curves for bile salts determination with both methods show good linearity with high coefficient of determination (R2) between 0.97 and 0.99. Method validation indicates good sensitivity with low relative standard deviation (RSD) (<10%), low limits of detection (LOD) of 0.4 versus 0.2 μg and limit of quantification (LOQ) of 1.4 versus 0.7 μg, for densitometric vs digital image analysis method, respectively. The bile salt hydrolase activity was found to be higher against glyco- than tauro-conjugated bile salts (LAB6; 100% vs >38%: LAB12; 100% vs >75%). The present findings strongly show that quantitative analysis via digitally-enhanced HPTLC offers a rapid quantitative analysis for deconjugation of bile salts by probiotics.

Graphical abstract

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Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Nur Syakila Rohawi, Kalavathy Ramasamy, Snezana Agatonovic-Kustrin, Siong Meng Lim

A quantitative assay using high-performance thin-layer chromatography (HPTLC) was developed to investigate bile salt hydrolase (BSH) activity in Pediococcus pentosaceus LAB6 and Lactobacillus plantarum LAB12 probiotic bacteria isolated from Malaysian fermented food. Lactic acid bacteria (LAB) were cultured in de Man Rogosa and Sharpe (MRS) broth containing 1 mmol/L of sodium-based glyco- and tauro-conjugated bile salts for 24 h. The cultures were centrifuged and the resultant cell free supernatant was subjected to chromatographic separation on a HPTLC plate. Conjugated bile salts were quantified by densitometric scans at 550 nm and results were compared to digital image analysis of chromatographic plates after derivatisation with anisaldehyde/sulfuric acid. Standard curves for bile salts determination with both methods show good linearity with high coefficient of determination (R 2 ) between 0.97 and 0.99. Method validation indicates good sensitivity with low relative standard deviation (RSD) (<10%), low limits of detection (LOD) of 0.4 versus 0.2 μg and limit of quantification (LOQ) of 1.4 versus 0.7 μg, for densitometric vs digital image analysis method, respectively. The bile salt hydrolase activity was found to be higher against glyco- than tauro-conjugated bile salts (LAB6; 100% vs >38%: LAB12; 100% vs >75%). The present findings strongly show that quantitative analysis via digitally-enhanced HPTLC offers a rapid quantitative analysis for deconjugation of bile salts by probiotics.

Graphical abstract

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A novel strategy for isolation and determination of sugars and sugar alcohols from conifers

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): B.A. Sarvin, A.P. Seregin, O.A. Shpigun, I.A. Rodin, A.N. Stavrianidi
The ultrasound-assisted extraction method for isolation of 17 sugars and sugar alcohols from conifers with a subsequent hydrophilic interaction liquid chromatography-tandem mass spectrometry method for their determination is proposed. The optimization of extraction parameters was carried out using Taguchi – L9 (34) orthogonal array experimental design for the following parameters—a methanol concentration in the extraction solution, an extraction time, a type of plant sample and an extraction temperature. The optimal ultrasound-assisted extraction conditions were—MeOH concentration – 30% (water – 70%), extraction time – 30 min, type of plant sample – II (grinded leaves 2–4 mm long), extraction temperature – 60 °C. Pure water and acetonitrile were used as eluents in gradient elution mode to separate the analytes. Direct determination of multiple sugars and sugar alcohols was carried out using a mass spectrometric detector operated in a multiple reaction monitoring mode, providing detection limits in the range between 0.1 and 20 ng/mL and good analytical characteristics of the method without derivatization. The developed approach was validated by multiple successive extraction method applied to test its performance on a series of 10 samples, i.e. 2 samples per each of 5 genera: Abies, Larix, Picea, Pinus (Pinaceae) and Juniperus (Cupressaceae), widely distributed in the boreal conifer forests of Eurasia. The novel strategy can be used for profiling of sugars and sugar alcohols in a wide range of plant species.

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): B.A. Sarvin, A.P. Seregin, O.A. Shpigun, I.A. Rodin, A.N. Stavrianidi

The ultrasound-assisted extraction method for isolation of 17 sugars and sugar alcohols from conifers with a subsequent hydrophilic interaction liquid chromatography-tandem mass spectrometry method for their determination is proposed. The optimization of extraction parameters was carried out using Taguchi – L9 (34) orthogonal array experimental design for the following parameters—a methanol concentration in the extraction solution, an extraction time, a type of plant sample and an extraction temperature. The optimal ultrasound-assisted extraction conditions were—MeOH concentration – 30% (water – 70%), extraction time – 30 min, type of plant sample – II (grinded leaves 2–4 mm long), extraction temperature – 60 °C. Pure water and acetonitrile were used as eluents in gradient elution mode to separate the analytes. Direct determination of multiple sugars and sugar alcohols was carried out using a mass spectrometric detector operated in a multiple reaction monitoring mode, providing detection limits in the range between 0.1 and 20 ng/mL and good analytical characteristics of the method without derivatization. The developed approach was validated by multiple successive extraction method applied to test its performance on a series of 10 samples, i.e. 2 samples per each of 5 genera: Abies, Larix, Picea, Pinus (Pinaceae) and Juniperus (Cupressaceae), widely distributed in the boreal conifer forests of Eurasia. The novel strategy can be used for profiling of sugars and sugar alcohols in a wide range of plant species.





Determination of aflatoxin and zearalenone analogs in edible and medicinal herbs using a group-specific immunoaffinity column coupled to ultra-high-performance liquid chromatography with tandem mass spectrometry

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Shujuan Sun, Kai Yao, Sijun Zhao, Pimiao Zheng, Sihan Wang, Yuyang Zeng, Demei Liang, Yuebin Ke, Haiyang Jiang
Six aflatoxins (AFs; AF B1, B2, G1, G2, M1 and M2) and six zearalenone (ZEN) analogs (ZEN, zearalanone, α-zeralanol, β-zeralanol, α-zearalenol, and β-zearalenol) were simultaneously extracted from edible and medicinal herbs using a group-specific immunoaffinity column (IAC) and then identified by ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS). The IAC was prepared by coupling N-hydroxysuccinimide-activated Sepharose 4B Fast Flow gel with two group-specific monoclonal antibodies. The column capacities to six AFs and six ZEN analogs ranged from 100.2 ng to 167.1 ng and from 59.5 ng to 244.4 ng, respectively. The IAC–UPLC–MS/MS method was developed and validated with three different matrices (Chinese yam [Dioscorea polystachya], Platycodon grandiflorum and coix seed [Semen Coicis]). Recoveries of twelve analytes from edible and medicinal herbs were in the range of 64.7%–112.1%, with relative standard deviations below 13.7%. The limits of quantification were in the range from 0.08 μg kg−1 to 0.2 μg kg−1. The method was proven to be sensitive and accurate, and suitable for the determination of real samples.

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Shujuan Sun, Kai Yao, Sijun Zhao, Pimiao Zheng, Sihan Wang, Yuyang Zeng, Demei Liang, Yuebin Ke, Haiyang Jiang

Six aflatoxins (AFs; AF B1, B2, G1, G2, M1 and M2) and six zearalenone (ZEN) analogs (ZEN, zearalanone, α-zeralanol, β-zeralanol, α-zearalenol, and β-zearalenol) were simultaneously extracted from edible and medicinal herbs using a group-specific immunoaffinity column (IAC) and then identified by ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS). The IAC was prepared by coupling N-hydroxysuccinimide-activated Sepharose 4B Fast Flow gel with two group-specific monoclonal antibodies. The column capacities to six AFs and six ZEN analogs ranged from 100.2 ng to 167.1 ng and from 59.5 ng to 244.4 ng, respectively. The IAC–UPLC–MS/MS method was developed and validated with three different matrices (Chinese yam [Dioscorea polystachya], Platycodon grandiflorum and coix seed [Semen Coicis]). Recoveries of twelve analytes from edible and medicinal herbs were in the range of 64.7%–112.1%, with relative standard deviations below 13.7%. The limits of quantification were in the range from 0.08 μg kg−1 to 0.2 μg kg−1. The method was proven to be sensitive and accurate, and suitable for the determination of real samples.





Multivariate analytics of chromatographic data: Visual computing based on moving window factor models

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Valentin Steinwandter, Michal Šišmiš, Patrick Sagmeister, Ulrich Bodenhofer, Christoph Herwig
Chromatography is one of the most versatile unit operations in the biotechnological industry. Regulatory initiatives like Process Analytical Technology and Quality by Design led to the implementation of new chromatographic devices. Those represent an almost inexhaustible source of data. However, the analysis of large datasets is complicated, and significant amounts of information stay hidden in big data.Here we present a new, top-down approach for the systematic analysis of chromatographic datasets. It is the goal of this approach to analyze the dataset as a whole, starting with the most important, global information. The workflow should highlight interesting regions (outliers, drifts, data inconsistencies), and help to localize those regions within a multi-dimensional space in a straightforward way.Moving window factor models were used to extract the most important information, focusing on the differences between samples. The prototype was implemented as an interactive visualization tool for the explorative analysis of complex datasets. We found that the tool makes it convenient to localize variances in a multidimensional dataset and allows to differentiate between explainable and unexplainable variance. Starting with one global difference descriptor per sample, the analysis ends up with highly resolute temporally dependent difference descriptor values, thought as a starting point for the detailed analysis of the underlying raw data.

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Valentin Steinwandter, Michal Šišmiš, Patrick Sagmeister, Ulrich Bodenhofer, Christoph Herwig

Chromatography is one of the most versatile unit operations in the biotechnological industry. Regulatory initiatives like Process Analytical Technology and Quality by Design led to the implementation of new chromatographic devices. Those represent an almost inexhaustible source of data. However, the analysis of large datasets is complicated, and significant amounts of information stay hidden in big data. Here we present a new, top-down approach for the systematic analysis of chromatographic datasets. It is the goal of this approach to analyze the dataset as a whole, starting with the most important, global information. The workflow should highlight interesting regions (outliers, drifts, data inconsistencies), and help to localize those regions within a multi-dimensional space in a straightforward way. Moving window factor models were used to extract the most important information, focusing on the differences between samples. The prototype was implemented as an interactive visualization tool for the explorative analysis of complex datasets. We found that the tool makes it convenient to localize variances in a multidimensional dataset and allows to differentiate between explainable and unexplainable variance. Starting with one global difference descriptor per sample, the analysis ends up with highly resolute temporally dependent difference descriptor values, thought as a starting point for the detailed analysis of the underlying raw data.





Chromatographic test methods for characterizing alkylsiloxane-bonded silica columns for reversed-phase liquid chromatography

Publication date: 15 August 2018 Source:Journal of Chromatography B, Volume 1092 Author(s): Colin F. Poole Major obstacles to formulating a simple retention mechanism for reversed-phase liquid chromatography have a direct impact on t…

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Colin F. Poole

Major obstacles to formulating a simple retention mechanism for reversed-phase liquid chromatography have a direct impact on the development of experimental methods for column characterization as they limit our capability to understand observed differences in retention at a system level. These problems arise from the heterogeneous composition of the stationary phase, the difficulty of providing a working definition for the phase ratio, and uncertainty as to whether the distribution mechanism for varied compounds is a partition, adsorption or mixed (combination) of these models. Retention factor and separation factor measurements offer little guidance as they represent an average of various and variable contributing factors that can only be interpreted by assuming a specific model. Column characterization methods have tended to ignore these difficulties by inventing a series of terms to describe column properties, such as hydrophobicity, hydrophilicity, silanol activity, steric resistance, etc., without proper definition. This has allowed multiple scales to be proposed for the same property which generally are only weakly correlated. Against this background we review the major approaches for the characterization of alkylsiloxane-bonded silica stationary phases employing prototypical compounds, the hydrophobic-subtraction model and the solvation parameter model. Those methods using prototypical compounds are limited by the lack of compounds with a singular dominant interaction. The multivariate approaches that extract column characteristic properties from the retention of varied compounds are more hopeful but it is important to be more precise in defining the characteristic column properties and cognizant that general interpretation of these properties for varied columns cannot escape the problem of a poor understanding of the distribution mechanism.





Simultaneous determination of six bioactive saponins from Rhizoma Panacis Japonici in rat plasma by UHPLC-MS/MS: Application to a pharmacokinetic study

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Hong Zheng, Feng Qiu, Hui Zhao, Jie Chen, Lei Wang, Haiyan Zou
A specific, sensitive and rapid ultra high performance liquid chromatography-tandem mass spectrometric (UHPLC-MS/MS) method was developed and validated for simultaneous determination of six major bioactive constituents in Rhizoma Panacis Japonici (RPJ), including oleanolic acid-type chikusetsusaponin V, IV, hemsgiganoside B, damarane-type ginsenoside Rb1, Rg1 and Re in rat plasma, using estazolam as the internal standard (IS). Plasma samples were pretreated with methanol/acetonitrile (1:1, V/V) for protein precipitation. Chromatographic separation was performed on an Agilent Eclipse Plus C18 column, using a gradient mobile phase consisting of methanol and 0.1% formic acid aqueous solution. A tandem mass spectrometric detection with an electrospray ionization (ESI) interface was conducted via multiple reaction monitoring (MRM) under positive ionization mode. For all the six analytes of interest, the calibration curves were linear in the concentration range of 2.00–500 ng/mL with r ≥ 0.9956. The intra- and inter-day precisions (in terms of relative standard deviation, RSD) were all below 10.2% and the accuracies (in terms of relative error, RE) were within −5.0% to 6.3% for all six analytes. Extraction recovery, matrix effect and stability data all met the acceptance criteria of FDA guideline for bioanalytical method validation. The developed method was applied to the pharmacokinetic study in rat. After oral administration of the total saponins from RPJ, six analytes were quickly absorbed into the blood and presented the phenomenon of double peaks. Among the six analytes, ginsenoside Rb1 showed slowest elimination from plasma with a t1/2z of 16.00 h, while that of the others were between 1.72 and 5.62 h. In conclusion, the developed method was successfully used to simultaneously analyze major oleanolic acid-type and damarane-type saponins of RPJ in rat plasma after oral administration.

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Hong Zheng, Feng Qiu, Hui Zhao, Jie Chen, Lei Wang, Haiyan Zou

A specific, sensitive and rapid ultra high performance liquid chromatography-tandem mass spectrometric (UHPLC-MS/MS) method was developed and validated for simultaneous determination of six major bioactive constituents in Rhizoma Panacis Japonici (RPJ), including oleanolic acid-type chikusetsusaponin V, IV, hemsgiganoside B, damarane-type ginsenoside Rb1, Rg1 and Re in rat plasma, using estazolam as the internal standard (IS). Plasma samples were pretreated with methanol/acetonitrile (1:1, V/V) for protein precipitation. Chromatographic separation was performed on an Agilent Eclipse Plus C18 column, using a gradient mobile phase consisting of methanol and 0.1% formic acid aqueous solution. A tandem mass spectrometric detection with an electrospray ionization (ESI) interface was conducted via multiple reaction monitoring (MRM) under positive ionization mode. For all the six analytes of interest, the calibration curves were linear in the concentration range of 2.00–500 ng/mL with r ≥ 0.9956. The intra- and inter-day precisions (in terms of relative standard deviation, RSD) were all below 10.2% and the accuracies (in terms of relative error, RE) were within −5.0% to 6.3% for all six analytes. Extraction recovery, matrix effect and stability data all met the acceptance criteria of FDA guideline for bioanalytical method validation. The developed method was applied to the pharmacokinetic study in rat. After oral administration of the total saponins from RPJ, six analytes were quickly absorbed into the blood and presented the phenomenon of double peaks. Among the six analytes, ginsenoside Rb1 showed slowest elimination from plasma with a t 1/2z of 16.00 h, while that of the others were between 1.72 and 5.62 h. In conclusion, the developed method was successfully used to simultaneously analyze major oleanolic acid-type and damarane-type saponins of RPJ in rat plasma after oral administration.





First report on the pharmacokinetic profile of nimbolide, a novel anticancer agent in oral and intravenous administrated rats by LC/MS method

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Shandilya Mahamuni Baira, Amit Khurana, Jaganmohan Somagoni, R. Srinivas, Chandraiah Godugu, M.V.N. Kumar Talluri
Nimbolide is a novel, natural compound with promising potential as a drug candidate for anticancer activity. It is isolated from the Indian traditional medicinal plant Azadirachta indica popularly known as neem. The present study was undertaken to explore the oral bioavailability and pharmacokinetic characteristics of nimbolide in rats using the LC/QTOF/MS method. A simple protein precipitation method using acetonitrile was employed for extracting nimbolide from rat plasma. The chromatographic separation of nimbolide and the internal standard (regorafenib) was attained on an Aquity BEH C18 column (100 × 2.1 mm, 2.7 μm), using ACN and 0.1% of formic acid in water as mobile phase components in a gradient elution mode at a flow rate of 0.45 mL/min over a short run time of 4 min. A mass detection was carried out using target ions of [M + H]+ at m/z 467.2074 for nimbolide and m/z 483.0847 for the internal standard. The LC/MS method was validated and all the parameters were found well within the specified limits. The calibration curve was constructed in the range of 1–1000 ng/mL. The method shows good accuracy (91.66–97.12%) and precision (intra 2.21–6.92% CV and inter-day 2.56–4.62% CV). This developed LC/MS method was effectively applied to the pharmacokinetic study of nimbolide upon oral and intravenous administration in rats. In concordance with its physicochemical properties and high lipophilicity, we found that it shows poor oral absorption at different doses (10, 30 and 50 mg/kg). As expected, higher plasma levels were observed upon intravenous (10 mg/kg) administration. This method can be extended for evaluation of drug interaction and drug metabolism in rats as well as in humans. Moreover, our rapid and sensitive method may cater the need to accelerate the preclinical formulation development and lead optimization for future drug development of this potent anticancer agent. Further, our oral bioavailability studies demonstrated that nimbolide possesses poor oral absorption, which could be the probable reason for the delay in therapeutic translation of this promising agent for clinical use.

Graphical abstract

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Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Shandilya Mahamuni Baira, Amit Khurana, Jaganmohan Somagoni, R. Srinivas, Chandraiah Godugu, M.V.N. Kumar Talluri

Nimbolide is a novel, natural compound with promising potential as a drug candidate for anticancer activity. It is isolated from the Indian traditional medicinal plant Azadirachta indica popularly known as neem. The present study was undertaken to explore the oral bioavailability and pharmacokinetic characteristics of nimbolide in rats using the LC/QTOF/MS method. A simple protein precipitation method using acetonitrile was employed for extracting nimbolide from rat plasma. The chromatographic separation of nimbolide and the internal standard (regorafenib) was attained on an Aquity BEH C18 column (100 × 2.1 mm, 2.7 μm), using ACN and 0.1% of formic acid in water as mobile phase components in a gradient elution mode at a flow rate of 0.45 mL/min over a short run time of 4 min. A mass detection was carried out using target ions of [M + H]+ at m/z 467.2074 for nimbolide and m/z 483.0847 for the internal standard. The LC/MS method was validated and all the parameters were found well within the specified limits. The calibration curve was constructed in the range of 1–1000 ng/mL. The method shows good accuracy (91.66–97.12%) and precision (intra 2.21–6.92% CV and inter-day 2.56–4.62% CV). This developed LC/MS method was effectively applied to the pharmacokinetic study of nimbolide upon oral and intravenous administration in rats. In concordance with its physicochemical properties and high lipophilicity, we found that it shows poor oral absorption at different doses (10, 30 and 50 mg/kg). As expected, higher plasma levels were observed upon intravenous (10 mg/kg) administration. This method can be extended for evaluation of drug interaction and drug metabolism in rats as well as in humans. Moreover, our rapid and sensitive method may cater the need to accelerate the preclinical formulation development and lead optimization for future drug development of this potent anticancer agent. Further, our oral bioavailability studies demonstrated that nimbolide possesses poor oral absorption, which could be the probable reason for the delay in therapeutic translation of this promising agent for clinical use.

Graphical abstract

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Simultaneous measurement of folate cycle intermediates in different biological matrices using liquid chromatography–tandem mass spectrometry

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092
Author(s): Jatin Nandania, Meri Kokkonen, Liliya Euro, Vidya Velagapudi
The folate cycle is an essential metabolic pathway in the cell, involved in nucleotide synthesis, maintenance of the redox balance in the cell, methionine metabolism and re-methylation reactions. Standardised methods for the measurement of folate cycle intermediates in different biological matrices are in great demand. Here we describe a rapid, sensitive, precise and accurate liquid chromatographic–tandem mass spectrometric (LC–MS/MS) method with a wide calibration curve range and a short run time for the simultaneous determination of folate cycle metabolites, including tetrahydrofolic acid (THF), 5‑methyl THF, 5‑formyl THF, 5,10‑methenyl THF, 5,10‑methylene THF, dihydrofolic acid (DHF) and folic acid in different biological matrices. Extraction of folate derivatives from soft and hard tissue samples as well as from adherent cells was achieved using homogenisation in buffer, while extraction from the whole blood and plasma relied on the anion exchange solid-phase extraction (SPE) method. Chromatographic separation was completed using a Waters Atlantis dC18 2.0 × 100 mm, 3-μ column with a gradient elution using formic acid in water (0.1% v/v) and acetonitrile as the mobile phases. LC gradient started with 95% of the aqueous phase which was gradually changed to 95% of the organic phase during 2.70 min in order to separate the selected metabolites. The analytes were separated with a run time of 5 min at a flow rate of 0.300 mL/min and detected using a Waters Xevo-TQS triple quadrupole mass spectrometer in the multiple reaction monitoring mode (MRM) at positive polarity. The instrument response was linear over a calibration range of 0.5 to 2500 ng/mL (r2 > 0.980). The developed bioanalytical method was thoroughly validated in terms of accuracy, precision, linearity, recovery, sensitivity and stability for tissue and blood samples. The matrix effect was compensated by using structurally similar isotope labelled internal standard (IS), 13C5‑methyl THF, for all folate metabolites. However, not all folate metabolites can be accurately quantified using this method due to their high interconversion rates especially at low pH. This applies to 5,10‑methylene THF which interconverts into THF, and 5,10‑methenyl‑THF interconverting into 5‑formyl‑THF. Using this method, we measured folate cycle intermediates in mouse bone marrow cells and plasma, in human whole blood; in mouse muscle, liver, heart and brain samples.

Publication date: 15 August 2018
Source:Journal of Chromatography B, Volume 1092

Author(s): Jatin Nandania, Meri Kokkonen, Liliya Euro, Vidya Velagapudi

The folate cycle is an essential metabolic pathway in the cell, involved in nucleotide synthesis, maintenance of the redox balance in the cell, methionine metabolism and re-methylation reactions. Standardised methods for the measurement of folate cycle intermediates in different biological matrices are in great demand. Here we describe a rapid, sensitive, precise and accurate liquid chromatographic–tandem mass spectrometric (LC–MS/MS) method with a wide calibration curve range and a short run time for the simultaneous determination of folate cycle metabolites, including tetrahydrofolic acid (THF), 5‑methyl THF, 5‑formyl THF, 5,10‑methenyl THF, 5,10‑methylene THF, dihydrofolic acid (DHF) and folic acid in different biological matrices. Extraction of folate derivatives from soft and hard tissue samples as well as from adherent cells was achieved using homogenisation in buffer, while extraction from the whole blood and plasma relied on the anion exchange solid-phase extraction (SPE) method. Chromatographic separation was completed using a Waters Atlantis dC18 2.0 × 100 mm, 3-μ column with a gradient elution using formic acid in water (0.1% v/v) and acetonitrile as the mobile phases. LC gradient started with 95% of the aqueous phase which was gradually changed to 95% of the organic phase during 2.70 min in order to separate the selected metabolites. The analytes were separated with a run time of 5 min at a flow rate of 0.300 mL/min and detected using a Waters Xevo-TQS triple quadrupole mass spectrometer in the multiple reaction monitoring mode (MRM) at positive polarity. The instrument response was linear over a calibration range of 0.5 to 2500 ng/mL (r2 > 0.980). The developed bioanalytical method was thoroughly validated in terms of accuracy, precision, linearity, recovery, sensitivity and stability for tissue and blood samples. The matrix effect was compensated by using structurally similar isotope labelled internal standard (IS), 13C5‑methyl THF, for all folate metabolites. However, not all folate metabolites can be accurately quantified using this method due to their high interconversion rates especially at low pH. This applies to 5,10‑methylene THF which interconverts into THF, and 5,10‑methenyl‑THF interconverting into 5‑formyl‑THF. Using this method, we measured folate cycle intermediates in mouse bone marrow cells and plasma, in human whole blood; in mouse muscle, liver, heart and brain samples.