A new issue of this journal has just
been published. To see abstracts of the papers it contains (with links through
to the full papers) click here:
Selected
papers from the latest issue:
A sensitive LC–MS/MS assay for the simultaneous analysis of the major active components of silymarin in human plasma
27 July 2012,
13:20:17
Publication year:
2012
Source:Journal of Chromatography B, Volume 902
Bryan J. Brinda, Hao-Jie Zhu, John S. Markowitz
Silymarin, an extract of crushed achenes of the milk thistle plant Silybum marianum is a multi-constituent mixture, 70–80% of which consists of a complex assortment containing the flavonolignans silybin A and B, isosilybin A and B, silydianin, and silychristin, and the flavonoid taxifolin. To date, numerous pharmacological actions of the silymarin extract have been documented in the biomedical literature, including hepatoprotective, anti-inflammatory, anti-tumor, and anti-fibrotic activities. The present study describes a novel liquid chromatographic–tandem mass spectrometric method for simultaneous analysis of silychristin, silydianin, silybin A and silybin B, isosilybin A and isosilybin B, and taxifolin in human plasma employing liquid–liquid extraction. This assay provides excellent resolution of the individual silymarin constituents via utilization of a 100A 250mm×2mm, 5μm C18 column with the mobile phase consisting of 51% methanol, 0.1% formic acid, and 10mM ammonium acetate. The lower limit of quantification was 2ng/ml for each constituent. Calibration curves were linear over the range from 2ng/ml to 100ng/ml for all analytes (r 2 >0.99). The intra- and inter-day accuracies were 91–106.5% and 95.1–111.9%, respectively. The intra- and inter-day precision was within 10.5%. Additionally, recovery, stability, and matrix effects were fully validated as well. This method was successfully applied to human plasma samples from subjects treated with the milk thistle extract Legalon®.
Source:Journal of Chromatography B, Volume 902
Bryan J. Brinda, Hao-Jie Zhu, John S. Markowitz
Silymarin, an extract of crushed achenes of the milk thistle plant Silybum marianum is a multi-constituent mixture, 70–80% of which consists of a complex assortment containing the flavonolignans silybin A and B, isosilybin A and B, silydianin, and silychristin, and the flavonoid taxifolin. To date, numerous pharmacological actions of the silymarin extract have been documented in the biomedical literature, including hepatoprotective, anti-inflammatory, anti-tumor, and anti-fibrotic activities. The present study describes a novel liquid chromatographic–tandem mass spectrometric method for simultaneous analysis of silychristin, silydianin, silybin A and silybin B, isosilybin A and isosilybin B, and taxifolin in human plasma employing liquid–liquid extraction. This assay provides excellent resolution of the individual silymarin constituents via utilization of a 100A 250mm×2mm, 5μm C18 column with the mobile phase consisting of 51% methanol, 0.1% formic acid, and 10mM ammonium acetate. The lower limit of quantification was 2ng/ml for each constituent. Calibration curves were linear over the range from 2ng/ml to 100ng/ml for all analytes (r 2 >0.99). The intra- and inter-day accuracies were 91–106.5% and 95.1–111.9%, respectively. The intra- and inter-day precision was within 10.5%. Additionally, recovery, stability, and matrix effects were fully validated as well. This method was successfully applied to human plasma samples from subjects treated with the milk thistle extract Legalon®.
Highlights
► Silymarin extract contains numerous bioactive flavonolignans and flavonoids. ► Analysis of silychristin, silydianin, silybin A and B, isosilybin A and B, and taxifolin. ► Pure standard compounds were utilized for absolute quantification. ► The lower limit of quantification was 2ng/ml for each analyte. ► Method was applied to human plasma samples from subjects treated with Legalon®.Quantification of human serum transferrin using liquid chromatography–tandem mass spectrometry based targeted proteomics
27 July 2012,
13:20:17
Publication year:
2012
Source:Journal of Chromatography B, Volume 902
Ying Yu, Jinhui Xu, Yuan Liu, Yun Chen
Currently, the absolute quantification of human transferrin (hTRF) is based on several techniques other than mass spectrometry. Although these techniques provide valuable information on protein levels and can be extremely sensitive, they often lack the specificity and reproducibility that can be provided by mass spectrometry. In this study, a liquid chromatography–tandem mass spectrometry (LC/MS/MS) based targeted proteomics assay was developed and validated for the determination of transferrin in human serum. We selected the tryptic peptide 108EDPQTFYYAVAVVK121 as the surrogate analyte for quantification and used a stable isotope-labeled synthetic peptide with this sequence as an internal standard. Sample cleanup and enrichment were achieved using solid phase extraction. The validated calibration range was from 500 to 5000ng/mL. The intra- and inter-day precisions were less than 4.9% and 9.0%, respectively. The bias for the quality control (QC) samples was less than 5.4%. Finally, this assay was successfully applied to the quantitative analysis of transferrin in clinical samples. The obtained values were assessed by independently measuring transferrin in the same samples using a commercially available immunoturbidimetric assay. As a result, the absolute concentrations determined by the LC/MS/MS assay compared well with those obtained with the immunoturbidimetric method; however, the LC/MS/MS assay afforded more reliable transferrin values at low concentrations.
Source:Journal of Chromatography B, Volume 902
Ying Yu, Jinhui Xu, Yuan Liu, Yun Chen
Currently, the absolute quantification of human transferrin (hTRF) is based on several techniques other than mass spectrometry. Although these techniques provide valuable information on protein levels and can be extremely sensitive, they often lack the specificity and reproducibility that can be provided by mass spectrometry. In this study, a liquid chromatography–tandem mass spectrometry (LC/MS/MS) based targeted proteomics assay was developed and validated for the determination of transferrin in human serum. We selected the tryptic peptide 108EDPQTFYYAVAVVK121 as the surrogate analyte for quantification and used a stable isotope-labeled synthetic peptide with this sequence as an internal standard. Sample cleanup and enrichment were achieved using solid phase extraction. The validated calibration range was from 500 to 5000ng/mL. The intra- and inter-day precisions were less than 4.9% and 9.0%, respectively. The bias for the quality control (QC) samples was less than 5.4%. Finally, this assay was successfully applied to the quantitative analysis of transferrin in clinical samples. The obtained values were assessed by independently measuring transferrin in the same samples using a commercially available immunoturbidimetric assay. As a result, the absolute concentrations determined by the LC/MS/MS assay compared well with those obtained with the immunoturbidimetric method; however, the LC/MS/MS assay afforded more reliable transferrin values at low concentrations.
Highlights
► A novel LC/MS/MS-based targeted proteomics assay was developed and validated. ► Protein digestion efficiency and surrogate peptide selection were discussed. ► The LC/MS/MS assay was compared with a commercial immunoturbidimetric method. ► Clinical monitoring of prospective protein biomarkers could be achieved by LC/MS/MS.Development, validation and application of a sensitive LC–MS/MS method for the quantification of thalidomide in human serum, cells and cell culture medium
27 July 2012,
13:20:17
Publication year:
2012
Source:Journal of Chromatography B, Volume 902
Sandra Roche, Louise Sewell, Justine Meiller, Kasper Pedersen, Rajesh Rajpal, Peter O’Gorman, Martin Clynes, Robert O’Connor
A simple, robust, sensitive and selective liquid chromatography tandem mass spectrometry (LC–MS/MS) method for the quantification of thalidomide was developed and validated. The method was applied to thalidomide quantification in three different types of biological samples. Thalidomide was extracted from human serum (100μL), cells (2.5×105), or cell culture media (100μL) by LLE and separated on a Prodigy C18 (150mm×4.0mm, 5μm i.d.) column with isocratic elution using water/acetonitrile (70/30, v/v) 0.1% formic acid, at a flow rate of 0.5mL/min, with umbelliferone (600ng/mL) as an internal standard. Thalidomide was quantified using a triple quadrupole mass spectrometer operated in multi-reaction-monitoring mode using positive electrospray ionisation. The method was validated in two separate thalidomide concentration ranges; human serum (0.05–20μg/mL) and in vitro cells (0.78–50ng) with an inter-day precision of 1.8% and 1.9% and average accuracy of 100% and 101% in serum and cells respectively. Despite the use of small sample volume, the limit of quantification for thalidomide in serum was determined to be 3ng/mL. The method was successfully employed to measure levels of thalidomide in cancer patient serum and cell culture model systems. Although cellular levels were quantifiable, thalidomide was shown to be unstable under in vitro conditions with a half life of approximately 2h. In patient samples, circulating serum levels showed a broad correlation with dose and uncovered some patient compliance issues.
Source:Journal of Chromatography B, Volume 902
Sandra Roche, Louise Sewell, Justine Meiller, Kasper Pedersen, Rajesh Rajpal, Peter O’Gorman, Martin Clynes, Robert O’Connor
A simple, robust, sensitive and selective liquid chromatography tandem mass spectrometry (LC–MS/MS) method for the quantification of thalidomide was developed and validated. The method was applied to thalidomide quantification in three different types of biological samples. Thalidomide was extracted from human serum (100μL), cells (2.5×105), or cell culture media (100μL) by LLE and separated on a Prodigy C18 (150mm×4.0mm, 5μm i.d.) column with isocratic elution using water/acetonitrile (70/30, v/v) 0.1% formic acid, at a flow rate of 0.5mL/min, with umbelliferone (600ng/mL) as an internal standard. Thalidomide was quantified using a triple quadrupole mass spectrometer operated in multi-reaction-monitoring mode using positive electrospray ionisation. The method was validated in two separate thalidomide concentration ranges; human serum (0.05–20μg/mL) and in vitro cells (0.78–50ng) with an inter-day precision of 1.8% and 1.9% and average accuracy of 100% and 101% in serum and cells respectively. Despite the use of small sample volume, the limit of quantification for thalidomide in serum was determined to be 3ng/mL. The method was successfully employed to measure levels of thalidomide in cancer patient serum and cell culture model systems. Although cellular levels were quantifiable, thalidomide was shown to be unstable under in vitro conditions with a half life of approximately 2h. In patient samples, circulating serum levels showed a broad correlation with dose and uncovered some patient compliance issues.
Highlights
► We developed a sensitive LCMS method for thalidomide with an LOQ of 3ng/mL in serum. ► The sample preparation, LLE, gives higher sample recovery than previous methods. ► In patient serum we detected thalidomide levels ranging from 25ng/mL to 1407ng/mL. ► We quantified thalidomide degradation in vitro with 50% remaining after 2h.Development and full validation of an UPLC-MS/MS method for the determination of an anti-allergic indolinone derivative in rat plasma, and application to a preliminary pharmacokinetic study
27 July 2012,
13:20:17
Publication year:
2012
Source:Journal of Chromatography B, Volume 902
Mouhssin Oufir, Chethan Sampath, Veronika Butterweck, Matthias Hamburger
The natural product (E,Z)-3-(4-hydroxy-3,5-dimethoxybenzylidene)indolin-2-one (indolinone) was identified some years ago as a nanomolar inhibitor of FcɛRI-receptor dependent mast cell degranulation. To further explore the potential of the compound, we established an UPLC-MS/MS assay for dosage in rat plasma. The method was fully validated according to FDA Guidance for industry. Results of this validation and long term stability study demonstrate that the method in lithium heparinized rat plasma is specific, accurate, precise and capable of producing reliable results according to recommendations of international guidelines. The method was validated with a LLOQ of 30.0ng/mL and an ULOQ of 3000ng/mL. The response versus concentration data were fitted with a first order polynomial with 1/X 2 weighting. No matrix effect was observed when using three independent sources of rat plasma. The average extraction recovery was consistent over the investigated range. This validation in rat plasma demonstrated that indolinone was stable for 190 days when stored below −65°C; for 4 days at 10°C in the autosampler; for 4h at RT, and during three successive freeze/thaw cycles at −65°C. Preliminary pharmacokinetic data were obtained in male Sprague–Dawley rats (2mg/kg BW i.v.). Blood samples taken from 0 to 12h after injection were collected, and data analyzed with WinNonlin. A short half-life (4.30±0.14min) and a relatively high clearance (3.83±1.46L/h/kg) were found.
Source:Journal of Chromatography B, Volume 902
Mouhssin Oufir, Chethan Sampath, Veronika Butterweck, Matthias Hamburger
The natural product (E,Z)-3-(4-hydroxy-3,5-dimethoxybenzylidene)indolin-2-one (indolinone) was identified some years ago as a nanomolar inhibitor of FcɛRI-receptor dependent mast cell degranulation. To further explore the potential of the compound, we established an UPLC-MS/MS assay for dosage in rat plasma. The method was fully validated according to FDA Guidance for industry. Results of this validation and long term stability study demonstrate that the method in lithium heparinized rat plasma is specific, accurate, precise and capable of producing reliable results according to recommendations of international guidelines. The method was validated with a LLOQ of 30.0ng/mL and an ULOQ of 3000ng/mL. The response versus concentration data were fitted with a first order polynomial with 1/X 2 weighting. No matrix effect was observed when using three independent sources of rat plasma. The average extraction recovery was consistent over the investigated range. This validation in rat plasma demonstrated that indolinone was stable for 190 days when stored below −65°C; for 4 days at 10°C in the autosampler; for 4h at RT, and during three successive freeze/thaw cycles at −65°C. Preliminary pharmacokinetic data were obtained in male Sprague–Dawley rats (2mg/kg BW i.v.). Blood samples taken from 0 to 12h after injection were collected, and data analyzed with WinNonlin. A short half-life (4.30±0.14min) and a relatively high clearance (3.83±1.46L/h/kg) were found.
Highlights
► Indolinone is stable in rat plasma stored below −65°C during 190 days. ► Method in rat plasma for indolinone is specific, selective, precise and accurate. ► Indolinone showed a short half-life and a relatively high clearance in rat plasma.A fully integrated multi-column system for abundant protein depletion from serum/plasma
27 July 2012,
13:20:17
Publication year:
2012
Source:Journal of Chromatography B, Volume 902
Dariusz J. Janecki, Steven C Pomerantz, Eric J. Beil, Jennifer F. Nemeth
This work details the transformation of a conventional HPLC system to a low back pressure liquid chromatography set-up for automated serum/plasma depletion and fractionation. A Dionex U3000 HPLC was converted to low back pressure operation (125psi max) by replacing all narrow-bore lines to larger inner-diameter tubing. The system was configured to use two immunoaffinity columns, first for depletion of the top 14 most abundant proteins (Seppro IgY14), then for the next 200–300 proteins (Seppro SuperMix). The autosampler was dual-purposed for both injection and fraction collection. Both the flow-through and SuperMix bound proteins were collected in an automated fashion. Three samples could be depleted consecutively before the system required user intervention, and up to nine samples could be depleted within a 24h period. This study documents the validation of the instrument performance with a 90-patient sample set, demonstrating overall CVs for 86 of the 90 samples to be within the 95% confidence intervals. Additionally, there was excellent reproducibility within the same patient (biological replicates) across days.
Source:Journal of Chromatography B, Volume 902
Dariusz J. Janecki, Steven C Pomerantz, Eric J. Beil, Jennifer F. Nemeth
This work details the transformation of a conventional HPLC system to a low back pressure liquid chromatography set-up for automated serum/plasma depletion and fractionation. A Dionex U3000 HPLC was converted to low back pressure operation (125psi max) by replacing all narrow-bore lines to larger inner-diameter tubing. The system was configured to use two immunoaffinity columns, first for depletion of the top 14 most abundant proteins (Seppro IgY14), then for the next 200–300 proteins (Seppro SuperMix). The autosampler was dual-purposed for both injection and fraction collection. Both the flow-through and SuperMix bound proteins were collected in an automated fashion. Three samples could be depleted consecutively before the system required user intervention, and up to nine samples could be depleted within a 24h period. This study documents the validation of the instrument performance with a 90-patient sample set, demonstrating overall CVs for 86 of the 90 samples to be within the 95% confidence intervals. Additionally, there was excellent reproducibility within the same patient (biological replicates) across days.
Highlights
► A conventional HPLC system set-up for automated serum/plasma depletion. ► The system uses two immunoaffinity columns in series (Seppro IgY14 and SuperMix). ► The autosampler is dual-purposed for both injection and fraction collection. ► The system significantly speeds up the sample preparation for proteomic workflow.Direct urine analysis for the identification and quantification of selected benzodiazepines for toxicology screening
27 July 2012,
13:20:17
Publication year:
2012
Source:Journal of Chromatography B, Volume 902
Sevasti Karampela, Ioanna Vardakou, Ioannis Papoutsis, Artemis Dona, Chara Spiliopoulou, Sotirios Athanaselis, Constantinos Pistos
A simple and rapid LC/MS method with direct injection analysis was developed and validated for the identification and quantification of ten benzodiazepines (flunitrazepam, nordiazepam, diazepam, 7-aminoflunitrazepam, flurazepam, bromazepam, midazolam, alprazolam, temazepam and oxazepam) in human urine using diazepam-d5 as internal standard (IS). The main advantage of the proposed methodology is the minimal sample preparation procedure, as diluted urine samples were directly injected into LC/MS system. Electrospray ionization in positive mode using selected ion monitoring was chosen for the identification and quantification of the analytes. The linear range was 50–1000ng/mL for each analyte, with square correlation coefficient (r 2)≥0.981. Interday and intraday errors were found to be ≤5.72%. The LC/MS method was applied at ten real samples found initially to be positive and negative, using immunoassay technique. Finally the results were confirmed with GC/MS. The method demonstrates simplicity and fast sample preparation, accuracy and specificity of the analytes which make it suitable for replacement of immunoassay screening in urine avoiding thus false negative/false positive results. Using this method, laboratories may overcome the problem of high cost instrumentation such as LC–MS/MS by providing similar sensitivity and specificity with other methods.
Source:Journal of Chromatography B, Volume 902
Sevasti Karampela, Ioanna Vardakou, Ioannis Papoutsis, Artemis Dona, Chara Spiliopoulou, Sotirios Athanaselis, Constantinos Pistos
A simple and rapid LC/MS method with direct injection analysis was developed and validated for the identification and quantification of ten benzodiazepines (flunitrazepam, nordiazepam, diazepam, 7-aminoflunitrazepam, flurazepam, bromazepam, midazolam, alprazolam, temazepam and oxazepam) in human urine using diazepam-d5 as internal standard (IS). The main advantage of the proposed methodology is the minimal sample preparation procedure, as diluted urine samples were directly injected into LC/MS system. Electrospray ionization in positive mode using selected ion monitoring was chosen for the identification and quantification of the analytes. The linear range was 50–1000ng/mL for each analyte, with square correlation coefficient (r 2)≥0.981. Interday and intraday errors were found to be ≤5.72%. The LC/MS method was applied at ten real samples found initially to be positive and negative, using immunoassay technique. Finally the results were confirmed with GC/MS. The method demonstrates simplicity and fast sample preparation, accuracy and specificity of the analytes which make it suitable for replacement of immunoassay screening in urine avoiding thus false negative/false positive results. Using this method, laboratories may overcome the problem of high cost instrumentation such as LC–MS/MS by providing similar sensitivity and specificity with other methods.
Highlights
► We develop simpler and faster sample preparation method for the determination of benzodiazepines in urine. ► We overcome the problem of high cost instrumentation such as LC–MS/MS by providing similar sensitivity and specificity with other methods. ► We overcome false negative/false positive results when using immunoassay methods for benzodiazepines. ► The method is applicable in real clinical and forensic samples.Liquid chromatography–mass spectrometric determination of losartan and its active metabolite on dried blood spots
27 July 2012,
13:20:17
Publication year:
2012
Source:Journal of Chromatography B, Volume 902
R. Nageswara Rao, S. Satyanarayana Raju, R. Mastan Vali, G. Girija Sankar
A simple and rapid quantitative bioanalytical liquid chromatography–tandem mass spectrometric (LC–MS/MS) method for simultaneous determination of losartan and its active metabolite, losartan carboxylic acid on rat dried blood spots was developed and validated as per regulatory guidelines. Losartan and its metabolite were extracted from dried blood spots using 50% aqueous methanol and separated on Waters XTerra® RP18 (250mm×4.6mm, 5μm) column using mobile phase composed of 40% acetonitrile and 60% aqueous ammonium acetate (10mM). The eluents were monitored using ESI tandem mass spectrometric detection with negative polarity in MRM mode using ion transitions m/z 421.2→179.0, m/z 435.3→157.0 and m/z 427.3→193.0 for losartan, losartan carboxylic acid and Irbesartan (internal standard), respectively. The method was validated over the linear range of 1–200ng/mL and 5–1000ng/mL with lower limits of quantification of 1.0ng/mL and 5.0ng/mL for losartan and losartan carboxylic acid, respectively. Inter and intra-day precision and accuracy (Bias) were below 5.96% and between −2.8 and 1.5%, respectively. The mean recoveries of the analytes from dried blood spots were between 89% and 97%. No significant carry over and matrix effects were observed. The stability of stock solution, whole blood, dried blood spot and processed samples were tested under different conditions and the results were found to be well within the acceptable limits. Additional validation parameters such as influence of hematocrit and spot volume were also evaluated and found to be well within the acceptable limits.
Source:Journal of Chromatography B, Volume 902
R. Nageswara Rao, S. Satyanarayana Raju, R. Mastan Vali, G. Girija Sankar
A simple and rapid quantitative bioanalytical liquid chromatography–tandem mass spectrometric (LC–MS/MS) method for simultaneous determination of losartan and its active metabolite, losartan carboxylic acid on rat dried blood spots was developed and validated as per regulatory guidelines. Losartan and its metabolite were extracted from dried blood spots using 50% aqueous methanol and separated on Waters XTerra® RP18 (250mm×4.6mm, 5μm) column using mobile phase composed of 40% acetonitrile and 60% aqueous ammonium acetate (10mM). The eluents were monitored using ESI tandem mass spectrometric detection with negative polarity in MRM mode using ion transitions m/z 421.2→179.0, m/z 435.3→157.0 and m/z 427.3→193.0 for losartan, losartan carboxylic acid and Irbesartan (internal standard), respectively. The method was validated over the linear range of 1–200ng/mL and 5–1000ng/mL with lower limits of quantification of 1.0ng/mL and 5.0ng/mL for losartan and losartan carboxylic acid, respectively. Inter and intra-day precision and accuracy (Bias) were below 5.96% and between −2.8 and 1.5%, respectively. The mean recoveries of the analytes from dried blood spots were between 89% and 97%. No significant carry over and matrix effects were observed. The stability of stock solution, whole blood, dried blood spot and processed samples were tested under different conditions and the results were found to be well within the acceptable limits. Additional validation parameters such as influence of hematocrit and spot volume were also evaluated and found to be well within the acceptable limits.
Highlights
► A simple isocratic LC–MS/MS method was developed and validated for losartan and its active metabolite. ► First dried blood spot report on losartan and it active metabolite as sample collection technique. ► Stability of analytes on FTA cards was also studied. ► Good LC resolution was obtained between the analytes and IS.Characterization of taste-active compounds of various cherry wines and their correlation with sensory attributes
27 July 2012,
13:20:17
Publication year:
2012
Source:Journal of Chromatography B, Volume 902
Yunwei Niu, Xiaoming Zhang, Zuobing Xiao, Shiqing Song, Chengsheng Jia, Haiyan Yu, Lingling Fang, Chunhua Xu
Five cherry wines exhibiting marked differences in taste and mouthfeel were selected for the study. The taste and mouthfeel of cherry wines were described by four sensory terms as sour, sweet, bitter and astringent. Eight organic acids, seventeen amino acids, three sugars and tannic acid were determined by high performance liquid chromatography (HPLC). Five phenolic acids were determined by ultra performance liquid chromatography coupled with mass spectrometry (UPLC–MS). The relationship between these taste-active compounds, wine samples and sensory attributes was modeled by partial least squares regression (PLSR). The regression analysis indicated tartaric acid, methionine, proline, sucrose, glucose, fructose, asparagines, serine, glycine, threonine, phenylalanine, leucine, gallic acid, chlorogenic acid, vanillic acid, arginine and tannic acid made a great contribution to the characteristic taste or mouthfeel of cherry wines.
Source:Journal of Chromatography B, Volume 902
Yunwei Niu, Xiaoming Zhang, Zuobing Xiao, Shiqing Song, Chengsheng Jia, Haiyan Yu, Lingling Fang, Chunhua Xu
Five cherry wines exhibiting marked differences in taste and mouthfeel were selected for the study. The taste and mouthfeel of cherry wines were described by four sensory terms as sour, sweet, bitter and astringent. Eight organic acids, seventeen amino acids, three sugars and tannic acid were determined by high performance liquid chromatography (HPLC). Five phenolic acids were determined by ultra performance liquid chromatography coupled with mass spectrometry (UPLC–MS). The relationship between these taste-active compounds, wine samples and sensory attributes was modeled by partial least squares regression (PLSR). The regression analysis indicated tartaric acid, methionine, proline, sucrose, glucose, fructose, asparagines, serine, glycine, threonine, phenylalanine, leucine, gallic acid, chlorogenic acid, vanillic acid, arginine and tannic acid made a great contribution to the characteristic taste or mouthfeel of cherry wines.
Highlights
► Four sensory attributes of 5 cherry wines were evaluated. ► Thirty-three compounds were correlated to sensory attributes and wine samples through PLSR. ► Seventeen compounds mostly contributed to sensory attributes of cherry wines.Pharmacokinetics of conjugated metabolites in rat plasma after oral administration of tectoridin
27 July 2012,
13:20:17
Publication year:
2012
Source:Journal of Chromatography B, Volume 902
Jialin Qu, Jie Gao, Jiahong Sun, Lin Zhang, Toshiaki Makino, Dan Yuan
Tectoridin is a major isoflavone found in the flowers of Pueraria thomsonii Benth. It possesses estrogenic, hypoglycemic, anti-oxidant, and anti-inflammatory activities. In the present study, we evaluated the plasma pharmacokinetic profile of tectoridin in rats. We isolated a new metabolite, tectorigenin-7-O-glucuronide-4′-O-sulfate (Te-7G-4′S), from the bile of rats treated orally with tectoridin and determined its chemical structure by spectral analysis. Furthermore, we developed a selective and accurate method for the simultaneous quantification of tectoridin metabolites, including Te-7G-4′S, tectorigenin-7-O-glucuronide (Te-7G), tectorigenin-7-O-sulfate (Te-7S), and tectorigenin in rat plasma, and measured their plasma concentrations in rats orally administered tectoridin (200mg/kg). Plasma concentrations of Te-7G-4′S, Te-7G, Te-7S, and tectorigenin reached maximal values of 21.4±13.8μmol at 3.50±1.87h, 20.5±9.7μmol at 3.17±1.81h, 14.3±3.3μmol at 5.58±3.07h, and 8.67±3.07μmol at 4.92±2.87h, respectively. Enterohepatic recirculation resulted in double peaks or a flat concentration curve/time profile of the metabolites. Since plasma concentrations of tectorigenin conjugated metabolites were higher than those of the tectorigenin aglycone, it can be concluded that extensive phase II metabolism plays an important role in the pharmacokinetics of tectoridin and tectorigenin in vivo.
Source:Journal of Chromatography B, Volume 902
Jialin Qu, Jie Gao, Jiahong Sun, Lin Zhang, Toshiaki Makino, Dan Yuan
Tectoridin is a major isoflavone found in the flowers of Pueraria thomsonii Benth. It possesses estrogenic, hypoglycemic, anti-oxidant, and anti-inflammatory activities. In the present study, we evaluated the plasma pharmacokinetic profile of tectoridin in rats. We isolated a new metabolite, tectorigenin-7-O-glucuronide-4′-O-sulfate (Te-7G-4′S), from the bile of rats treated orally with tectoridin and determined its chemical structure by spectral analysis. Furthermore, we developed a selective and accurate method for the simultaneous quantification of tectoridin metabolites, including Te-7G-4′S, tectorigenin-7-O-glucuronide (Te-7G), tectorigenin-7-O-sulfate (Te-7S), and tectorigenin in rat plasma, and measured their plasma concentrations in rats orally administered tectoridin (200mg/kg). Plasma concentrations of Te-7G-4′S, Te-7G, Te-7S, and tectorigenin reached maximal values of 21.4±13.8μmol at 3.50±1.87h, 20.5±9.7μmol at 3.17±1.81h, 14.3±3.3μmol at 5.58±3.07h, and 8.67±3.07μmol at 4.92±2.87h, respectively. Enterohepatic recirculation resulted in double peaks or a flat concentration curve/time profile of the metabolites. Since plasma concentrations of tectorigenin conjugated metabolites were higher than those of the tectorigenin aglycone, it can be concluded that extensive phase II metabolism plays an important role in the pharmacokinetics of tectoridin and tectorigenin in vivo.
Highlights
► A new glucuronide-sulfate diconjugate was isolated and structurally determined for the first time. ► Three conjugate metabolites were simultaneously identified and quantified in rat plasma by HPLC–DAD and LC/TOF/MS. ► It provides helpful information for the potential therapeutic application of tectoridin-containing phytopharmacueticals.Quantification of HPLC-separated peptides and proteins by spectrofluorimetric detection of native fluorescence and mass spectrometry
27 July 2012,
13:20:17
Publication year:
2012
Source:Journal of Chromatography B, Volume 902
Suraj Saraswat, Bruce Snyder, Dragan Isailovic
Due to relatively low reproducibility of the ionization and differences when using buffers as mobile phases, the quantitative analysis by electrospray ionization mass spectrometry (ESI-MS) can be often challenging. In the present study, the native fluorescence of phenylalanine, tyrosine, and tryptophan was investigated as an improvement tool for the analytical quantification of peptides and proteins by HPLC–ESI-MS. Natively fluorescent amino acids as well as peptides, proteins, and protein digests were successfully separated by HPLC, and quantified with a spectrofluorimetric detector and ESI-MS. The two detectors were connected in series and enabled the sequential measurements of the fluorescence intensities as well as the measurements of the ion signals and mass spectral characterization of separated polypeptides. Fluorescence detector provided better linearity and repeatability of quantification than mass spectrometer, and similar limits of detection for most of biomolecules analyzed. The fluorescence signal was linear over 3–4 orders of magnitude with limits of detection in picomole or high femtomole range, depending on nature and number of natively fluorescent amino acid residues present in the analyzed polypeptides. Hence, native fluorescence of phenylalanine, tyrosine, and tryptophan can be used as a label-free methodology to facilitate quantification of peptides and proteins by LC–ESI-MS.
Source:Journal of Chromatography B, Volume 902
Suraj Saraswat, Bruce Snyder, Dragan Isailovic
Due to relatively low reproducibility of the ionization and differences when using buffers as mobile phases, the quantitative analysis by electrospray ionization mass spectrometry (ESI-MS) can be often challenging. In the present study, the native fluorescence of phenylalanine, tyrosine, and tryptophan was investigated as an improvement tool for the analytical quantification of peptides and proteins by HPLC–ESI-MS. Natively fluorescent amino acids as well as peptides, proteins, and protein digests were successfully separated by HPLC, and quantified with a spectrofluorimetric detector and ESI-MS. The two detectors were connected in series and enabled the sequential measurements of the fluorescence intensities as well as the measurements of the ion signals and mass spectral characterization of separated polypeptides. Fluorescence detector provided better linearity and repeatability of quantification than mass spectrometer, and similar limits of detection for most of biomolecules analyzed. The fluorescence signal was linear over 3–4 orders of magnitude with limits of detection in picomole or high femtomole range, depending on nature and number of natively fluorescent amino acid residues present in the analyzed polypeptides. Hence, native fluorescence of phenylalanine, tyrosine, and tryptophan can be used as a label-free methodology to facilitate quantification of peptides and proteins by LC–ESI-MS.
Highlights
► Sequential native fluorescence–ESI-MS quantification of HPLC-separated polypeptides is enabled. ► Peptides and proteins containing all natively fluorescent amino acids are quantified. ► Figures of merit for spectrofluorimetric and ESI-MS quantifications of natively fluorescent biomolecules are complementary. ► Native fluorescence provides better linearity and repeatability of quantification than ESI-MS. ► This is a label-free technique, which can facilitate quantification of peptides and proteins by LC–ESI-MS.Diffusion Split-Flow Thin Cell (SPLITT) system for protein separations
27 July 2012,
13:20:17
Publication year:
2012
Source:Journal of Chromatography B, Volume 902
Srinivas Merugu, Himanshu J. Sant, Bruce K. Gale
A diffusion Split-Flow Thin Cell (SPLITT) system was used to partially remove small peptides such as β2 microglobulin (β2M) and parathyroid hormone (PTH) in a continuous manner from an input flow stream while preserving most (over 97%) of the larger protein in the sample, such as albumin. To help determine the operating conditions for this work, a two-dimensional numerical model based on the Navier–Stokes equation and convection–diffusion equations was developed for diffusional SPLITT using COMSOL multiphysics software (COMSOL Inc., MA). These simulations were used to obtain the relationship between important operational parameters and the purification efficiency for proteins of interest. The diffusion-based SPLITT system was fabricated using xurography and was used to demonstrate protein purification based on the differences in size or diffusion coefficient of the sample. The results obtained from the experiments are compared with the mathematical model and show good agreement, while the variations between these results are discussed. The results show that significant portions of small peptides (>25%) can be removed while preserving larger proteins (up to 95%) in the carrier stream. A potential application of this technique is to be used as an additional step in kidney dialysis to remove toxins that are not effectively removed by current dialysis protocols.
Source:Journal of Chromatography B, Volume 902
Srinivas Merugu, Himanshu J. Sant, Bruce K. Gale
A diffusion Split-Flow Thin Cell (SPLITT) system was used to partially remove small peptides such as β2 microglobulin (β2M) and parathyroid hormone (PTH) in a continuous manner from an input flow stream while preserving most (over 97%) of the larger protein in the sample, such as albumin. To help determine the operating conditions for this work, a two-dimensional numerical model based on the Navier–Stokes equation and convection–diffusion equations was developed for diffusional SPLITT using COMSOL multiphysics software (COMSOL Inc., MA). These simulations were used to obtain the relationship between important operational parameters and the purification efficiency for proteins of interest. The diffusion-based SPLITT system was fabricated using xurography and was used to demonstrate protein purification based on the differences in size or diffusion coefficient of the sample. The results obtained from the experiments are compared with the mathematical model and show good agreement, while the variations between these results are discussed. The results show that significant portions of small peptides (>25%) can be removed while preserving larger proteins (up to 95%) in the carrier stream. A potential application of this technique is to be used as an additional step in kidney dialysis to remove toxins that are not effectively removed by current dialysis protocols.
No comments:
Post a Comment