An optimized UPLC-MS/MS method for human plasma amyloid-ß 42 and 40 measurement and application in Alzheimer's disease diagnosis.

Critical events in Alzheimer's disease (AD) involve an imbalance between the production and clearance of amyloid-ß (Aß) peptides from the brain. The ratio of Aß42 to Aß40 in plasma was useful for evaluating AD, but quantification is limited by factors including preanalytical analyte loss and insufficient sensitivity. The availability of a targeted UPLC-MS/MS method with adequate analytical sensitivity and accurate values traceable to the SI units is essential for implementing a strategy for assay standardization. A targeted UPLC-MS/MS method for plasma Aß42 and Aß40 quantification was developed based on selected characteristic peptides spiked by 15N-labeled Aß. The calibrator was assigned using an amino acid analysis reference method trace to SI units. UPLC-MS/MS conditions and sample preparation procedures were assessed. 59 plasma samples comparison were used to evaluate immunoassays. Additionally, two clinical cohorts were selected for diagnostic performance evaluation. The LOQ of Aß42 and Aß40 is 10 pg mL-1 and 20 pg mL-1, respectively. The linear range was 10-500 pg mL-1 for Aß42 and 20-1000 pg mL-1 for Aß40, recoveries between 95.3 % and 108.2 % for Aß42, 93.2 % and 104.1 % for Aß40, imprecisions were <7 %. The accuracy of method was validated by analysis of a certified reference material. Clinical cohorts for diagnostic performance evaluation shown that the area under the curve (AUC) for plasma Aß42 and Aß42/Aß40 to differentiate between AD and CN were 0.767 and 0.799, respectively. A robust UPLC-MS/MS method was developed and demonstrated that suitable for a wide range of plasma Aß42 and Aß40. Applied to the investigation of clinically discrepant results, this method can act as an arbiter of the concentration of plasma Aß42 and Aß40 present.

The hepatoprotective effect and mechanism of lotus leaf on liver injury induced by Genkwa Flos.

OBJECTIVES: As a traditional Chinese medicine, lotus leaf was reported to have significant hepatoprotective effect. To explore the hepatoprotective mechanism of lotus leaf, a rapid and reliable UPLC-MS/MS method was conducted to simultaneously determine six specific endogenous substances including 5-oxoproline, phenylalanine, tryptophan, C18 -phytosphingosine, lysophosphatidylcholine (16 : 0) and lysophosphatidylcholine (18 : 1). METHODS: With the help of HPLC-FT-ICR-MS, the chemical constituents of louts leaf extract were elucidated. By observing histopathological changes and determining hepatotoxicity-related biochemical indicators, rat model of liver injury was developed and the hepatoprotective effect of lotus leaf was verified. With the developed UPLC-MS/MS method, six endogenous metabolites related to hepatotoxicity were monitored to investigate the hepatoprotective mechanism of lotus leaf. KEY FINDINGS: In the qualitative analysis, a total of twenty compounds including ten flavonoids, nine alkaloids and one proanthocyanidin were identified. Based on the results of determining six endogenous metabolites related to hepatotoxicity, it was predicted that the hepatoprotective mechanism of lotus leaf might be related to glutathione metabolism, phenylalanine metabolism, tryptophan metabolism, sphingolipid metabolism and phospholipid metabolism. CONCLUSIONS: This study could be a meaningful investigation to provide mechanistic insights into the hepatoprotective effect of lotus leaf and further lay a theoretical basis for the clinical application of lotus leaf.

Phosphocyclocreatine is the dominant form of cyclocreatine in control and creatine transporter deficiency patient fibroblasts.

Creatine transporter deficiency (CTD) is a metabolic disorder resulting in cognitive, motor, and behavioral deficits. Cyclocreatine (cCr), a creatine analog, has been explored as a therapeutic strategy for the treatment of CTD. We developed a rapid, selective, and accurate HILIC ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method to simultaneously quantify the intracellular concentrations of cCr, creatine (Cr), creatine-d3 (Cr-d3), phosphocyclocreatine (pcCr), and phosphocreatine (pCr). Using HILIC-UPLC-MS/MS, we measured cCr and Cr-d3 uptake and their conversion to the phosphorylated forms in primary human control and CTD fibroblasts. Altogether, the data demonstrate that cCr enters cells and its dominant intracellular form is pcCr in both control and CTD patient cells. Therefore, cCr may replace creatine as a therapeutic strategy for the treatment of CTD.

Study on Plasma Protein Binding Rate of Cajanonic Acid A with Different Species of Plasma by Ultrafiltration Combined with UPLC-MS/MS / 中国药房

OBJECTIVE： To compare plasma protein binding rate of cajanonic acid A with different species of plasma. METHODS：Using UPLC-MS/MS as the detection means. Plasma protein binding rate of low， medium and high concentrations of cajanonic acid A （2.5， 5， 20 μg/mL） with rats， rabbits and human plasma were determined by ultrafiltration method. The chromatographic conditions included that Waters BEH C18 as chromatographic column， WatersVanGuard BEH C18 as guard column， mobile phase consisted of ultrapure water solution containing 0.01％ formic acid （solvent A） and acetonitrile solution of 0.01％ formic acid （solvent B） gradient elution， at the flow rate of 0.15 mL/min， column temperature of 30 ℃， sample size of 2 μL. Mass spectrum condition included that ESI， negative ion mode acquisition， capillary voltage of 1.5 kV， cone voltage of 30 V， ion source temperature of 100 ℃， desolvent gas temperature of 400 ℃， cone gas flow of 50 L/h， desolvent gas flow of 800 L/h， scanning range of m/z 50→1 200. RESULTS： At the concentration of 2.5， 5 and 20 μg/mL， the plasma protein binding rates of cajanonic acid A were （75.63±0.90）％， （98.30±0.03）％ and （99.42±0.01）％ in the rats plasma； （79.61±1.08）％， （98.48±0.10）％ and （99.42±0.03）％ in rabbits plasma （n＝3）； （76.74±1.22）％， （97.99±0.11）％ and （99.37±0.01）％ in human plasma （n＝3）. At the concentration of 2.5 μg/mL， plasma protein binding rates of cajanonic acid A in plasma of rats and human were significantly lower than that in plasma of rabbits （P＜0.05）. CONCLUSIONS： The plasma protein binding rate of 5，20 μg/mL cajanonic acid A with rats， rabbits and human plasma are higher than that of 2.5 μg/mL cajanonic acid A. There is significant difference in plasma protein binding rate of 2.5 μg/mL cajanonic acid A with different species of plasma，and there is no significant difference in plasma protein binding rate of 5， 20 μg/mL cajanonic acid A with different species of plasma.

Assessing the presence of enrofloxacin and ciprofloxacin in piggery wastewater and their adsorption behaviour onto solid materials, with a newly developed chromatographic method.

Veterinary antibiotics could enter the environment after the application of manure or farm wastewater on soil as fertilizer. In this study, a UPLC-MS/MS analytical method was developed and validated for the simultaneous determination of enrofloxacin (ENR) and ciprofloxacin (CIP) at environmental relevant concentrations in piggery wastewater, piggery wastewater solids, agricultural soil and ground water with good performance characteristics. The method recovery for ENR and CIP was 94.2 and 89.9% in the filtered piggery wastewater, 81.3 and 82% in the wastewater solid material, 78.1 and 76.8% in the soil and 95.6 and 97.3% in the ground water. The Limit of Detection (LOD) and Limit of Quantification (LOQ) for ENR were 21 and 64 ng L-1 and for CIP was 18 and 54 ng L-1, respectively. The method was implemented to monitor ENR and CIP in the wastewater of a piggery facility in Cyprus which applied anaerobic treatment before the final disposal of the reclaimed water. The highest antibiotic concentrations were measured in the wastewater samples collected from the nursery, where ENR is continuously used, with average concentration 31.4 µg L-1 for ENR and 16.0 µg L-1 for CIP. After the anaerobic digester, the two antibiotics were found only on the solid matter of the treated wastewater with an average concentration of 1.7 µg kg-1 for ENR and 1.0 µg kg-1 for CIP. The antibiotics adsorption at pH = 7 on clay soil, quartz sand and on solid matter isolated from the piggery wastewater was found to be higher than 95% for all solid materials. The concentration of the antibiotics in soil samples taken from a field where reclaimed piggery wastewater was applied for 10 years and in samples of groundwater from a nearby well was found for all samples below the LOD.

A validated UPLC-MS/MS method for the analysis of linezolid and a novel oxazolidinone derivative (PH027) in plasma and its application to tissue distribution study in rabbits.

OBJECTIVES: Linezolid is the first approved oxazolidinone antibacterial agent, whereas PH027 is a novel compound of the same class that exhibits good in vitro antibacterial activity. The objective of this study was to develop an UPLC-MS/MS assay for the analysis of linezolid and PH027 in plasma and to apply the method for comparative pharmacokinetic and tissue distribution studies of both compounds. METHOD: Plasma samples and calibrators were extracted with diethyl ether after addition of the internal standard solution. After evaporation of the ether layer, the residue was reconstituted in mobile phase and injected into UPLC-MS/MS. The mobile phase consisted of 2mM ammonium acetate buffer solution and acetonitrile (70:30) at a flow rate of 0.2ml/min. Separation was achieved using UPLC BEH C18 column, and quantitative determination of the analytes was performed using multiple-reaction monitoring (MRM) scanning mode. The method was validated by analyzing quality control tissue homogenate samples, and was applied to analyze tissue homogenate samples obtained following IV injections of linezolid and PH027 in rabbits. RESULTS: The developed UPLC-MS/MS method was linear in the concentration range of 50-5000ng/ml. Validation of the method proved that the method's precision, selectivity and stability were all within the acceptable limits. Linezolid and PH027 concentrations were accurately determined in the quality control tissue homogenate samples, and analysis of samples obtained following IV administration of the two compounds showed that the tissue to plasma concentration ratio of PH027 was higher than that of linezolid probably due to its higher lipophilicity. CONCLUSIONS: The developed UPLC-MS/MS method for the analysis of linezolid and PH027 in rabbit's plasma can accurately determine the concentrations of these compounds in different tissues.

Simultaneous Determination of Multiple Components in Guanjiekang in Rat Plasma via the UPLC-MS/MS Method and Its Application in Pharmacokinetic Study.

Guanjiekang (GJK) that is formed by five medicinal herbs including Astragali Radix, Aconiti Lateralis Radix Praeparaia, Glycyrrhizae Radix et Rhizoma, Corydalis Rhizoma and Paeoniae Radix Alba was used for the treatment of rheumatoid arthritis (RA). However, the pharmacokinetic (PK) profile of active components in GJK remains unclear. This study aims to evaluate the pharmacokinetic behavior of seven representative active constituents in GJK (i.e., benzoylhypaconine, benzoylmesaconine, paeoniflorin, tetrahydropalmatine, calycosin-7-glucoside, formononetin and isoliquiritigenin) after oral administration of GJK in rats. A rapid, sensitive and reliable ultra-performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) method has been successfully developed for the simultaneous determination of these seven constituents in rat plasma. Chromatographic separation was achieved on a C18 column with a gradient elution program that consists of acetonitrile and water (containing 0.1% formic acid) at a flow rate of 0.35 mL/min. Detection was performed under the multiple reaction monitoring (MRM) in the positive electrospray ionization (ESI) mode. The calibration curves exhibited good linearity (R² > 0.99) over a wide concentration range for all constituents. The accuracies ranged from 92.9% to 107.8%, and the intra-day and inter-day precisions at three different levels were below 15%. Our PK results showed that these seven compounds were quickly absorbed after the administration of the GJK product, and Tmax ranged from 30 min to 189 min. The in vivo concentrations of paeoniflorin and isoliquiritigenin were significantly higher than the reported in vitro effective doses, indicating that they could partly contribute to the therapeutic effect of GJK. Therefore, we conclude that pharmacokinetic studies of representative bioactive chemicals after administration of complex herbal products are not only necessary but also feasible. Moreover, these seven compounds that were absorbed in vivo can be used as indicator standards for quality control and for determining pharmacokinetic behavior of herbal medicines in clinical studies.

Simultaneous profiling of eicosanoid metabolome in plasma by UPLC-MS/MS method: Application to identify potential makers for rheumatoid arthritis.

To evaluate the potential relationship between rheumatoid arthritis and arachidonic acid (AA) metabonomics via cyclooxygenase (COX) and lipoxygenase (LOX) pathways, a UPLC-MS/MS method has been developed and validated for simultaneous and quantitative profiling of eicosanoid metabolome in rat plasma. The analytes were extracted from plasma samples by protein precipitation procedure, and then separated on a Shim-pack XR-ODS column with mobile phase A (0.05% formic acid in water, pH=3.3 adjusted with dilute ammonium hydroxide) and mobile phase B [methanol: acetonitrile (20:80, v/v)]. The detection was performed on UPLC-MS/MS system with an electro spray ion source in the negative ion and multiple reaction-monitoring modes. The developed method was optimized to completely separate all twenty-three analytes and three internal standards in 12min. All standard calibration curves were linear and the calibration regression coefficients were ranged from 0.9903 to 0.9992 for all analytes. The recoveries of analytes were all more than 60%. By means of the method developed, the plasma samples from model rats and normal rats had been successfully determined. Results showed that AA and fifteen kinds of metabolites by LOX and COX pathways in model rat plasma were significant higher than those in normal ones(P<0.05), while 5-HpETE and LTD4 in model rat plasma were significantly lower than those in normal ones(P<0.05). The methods demonstrated the changes of eicosanoid metabolome occurring in plasma from rat subjects with rheumatoid arthritis. It could be a powerful manner to diagnostic and/or prognostic values for rheumatoid arthritis.

UPLC-MS/MS method for simultaneous determination of cyclophosphamide, docetaxel, doxorubicin and 5-fluorouracil in surface samples.

INTRODUCTION: There is certainly a great benefit to treatment with antineoplastic drugs for cancer patients with a life-threatening disease. However, for the workers who are exposed to these agents as part of their work practice, precautions should be taken to eliminate or reduce exposure as much as possible. OBJECTIVE: The aim of this study is to develop and validate a wipe sampling procedure followed by liquid chromatographic separation with electrospray ionization and a tandem mass spectrometric detection method for the simultaneous determination of cyclophosphamide (CP), docetaxel (DOC), doxorubicin (DOXO) and 5-fluorouracil (5-FU). METHOD: The chromatographic separation was carried out in 15min by applying a gradient elution of 0.1% formic acid and acetonitrile. MS/MS was performed on a triple quadrupole instrument in the multiple reaction monitoring (MRM) mode. RESULTS: The analytical range was linear between 3.5 to 300ng/mL for CP, 4 to 300ng/mL for DOC and DOXO and 2 to 300ng/mL for 5-FU. The present method offers a high sensitivity, with detection limits of 1.0ng/mL for CP, DOXO and DOC and 0.5ng/mL for 5-FU. The selectivity, accuracy (relative standard error between 82.3 and 113.9%) and precision (relative standard deviation between 1.2 and 14.2%) make the method suitable for the routine determination of these drugs to estimate the occupational exposure of personnel handling. CONCLUSIONS: The developed method allows a reliable assessment of exposure, which is one of the steps for evaluation the risk inherent to workers in contact with antineoplastic drugs.

Rutin-encapsulated chitosan nanoparticles targeted to the brain in the treatment of Cerebral Ischemia.

OBJECTIVE: Rutin, a potent antioxidant, has been reported to reduce the risk of ischemic disease. Our study aims to prepare rutin-encapsulated-chitosan nanoparticles (RUT-CS-NPs) via ionic gelation method and determine its results, based on different parameters i.e. surface morphology characterization, in-vitro or ex-vivo release, dynamic light scattering and differential scanning calorimetry (DSC), for treating cerebral ischemia. METHODS: UPLC-ESI-Q-TOF-MS/MS was used to evaluate the optimized RT-CS-NPs1 for brain-drug uptake as well as to follow-up the pharmacokinetics, bio-distrbution, brain-targeting efficiency and potential after intranasal administration (i.n.). KEY FINDINGS: A particle size of <100nm for the formulation, significantly affected by drug:CS ratio, and entrapment efficiency and loading capacity of 84.98%±4.18% and 39.48%±3.16%, respectively were observed for RUT. Pharmacokinetics, bio-distribution, brain-targeting efficiency (1443.48±39.39%) and brain drug-targeting potential (93.00±5.69%) showed enhanced bioavailability for RUT in brain as compared to intravenous administration. In addition; improved neurobehavioral activity, histopathology and reduced infarction volume effects were observed in middle cerebral artery occlusion (MCAO) induced cerebral ischemic rats model after i.n. administration of RUT-CS-NPs. CONCLUSION: A significant role of mucoadhesive-RT-CS-NPs1 as observed after high targeting potential and efficiency of the formulation prove; RUT-CS-NPs are more effectively accessed and target easily the brain.

In vitro absorption mechanism of Erigeron breviscapus extract in Caco-2 cell monolayer model / 中国药理学通报

Aim To study the absorption mechanism of apigenin-7-O-glucronide, 3,4-Dihydroxycinnamic acid and chlorogenic acid in Erigeron breviscapus extract ( Ebe) by Caco-2 cell monolayer model. Methods The three active ingredients were quantified by UPLC-MS/MS method, and the effect of Ebe concentrations, conveying times, pH values and P-glycoprotein inhibi-tor on the transport of three active ingredients were also investigated. Results Apigenin-7-O-glucronide and chlorogenic acid in Caco-2 cell monolayer model were time-dependent and concentration-dependent. The 3, 4-Dihydroxycinnamic acid in Caco-2 cell uptake was concentration-saturate and P-glycoprotein inhibitor was involved in the uptake process. Conclusion The mechanism of apigenin-7-O-glucronide and chlorogenic acid absorption in cells is mainly through passive trans-port, and the absorption of 3, 4-Dihydroxycinnamic acid is mainly realized by the carrier transport.

A Novel Sensitive Method to Measure Catechol-O-Methyltransferase Activity Unravels the Presence of This Activity in Extracellular Vesicles Released by Rat Hepatocytes.

There is a clear need for drug treatments to be selected according to the characteristics of an individual patient, in order to improve efficacy and reduce the number and severity of adverse drug reactions. One of the main enzymes to take into account in pharmacogenomics is catechol O-methyltransferase (COMT), which catalyzes the transfer of a methyl group from S-adenosylmethionine to catechols and catecholamines, like the neurotransmitters dopamine, epinephrine, and norepinephrine. Although, most of this enzyme is associated to intracellular vesicles, recently it has also been detected in extracellular vesicles secreted by hepatocytes and in serum circulating vesicles. COMT has implications in many neurological and psychiatric disorders like Parkinson's disease, chronic fatigue, pain response, schizophrenia, and bipolar disorders. Remarkably, genetic variations of COMT affect its activity and are associated to various human disorders from psychiatric diseases to estrogen-induced cancers. Consequently, the establishment of new methods to evaluate COMT activity is an important aspect to investigate the biology of this drug-metabolizing enzyme. Herein, we have developed a sensitive and selective method to determine COMT activity. We first optimized the activity in rat liver incubated with two different substrates; norepinephrine and dopamine. The enzymatically formed products (normetanephrine and 3-methoxytyramine, respectively) were extracted by solid-phase extraction using weak cation exchange cartridges, chromatographically separated, and detected and quantified using a mass spectrometer. The range of quantitation for both products was from 0.005 to 25 µg/mL. This methodology offers acceptable recovery for both enzymatic products (≥75%) and good accuracy and precision (≤15%). The lower limit of quantifications were 0.01 and 0.005 µM for 3-methoxytyramine and normetanephrine, respectively. Importantly, this sensitive assay was able to detect the presence of COMT activity in extracellular vesicles secreted by hepatocytes supporting a potential role of these vesicles in catecholamines and catecholestrogens metabolisms. In addition, the presence of COMT activity in extracellular vesicles opens new possibilities to develop tools to evaluate personalized drug response in a low invasive manner.

Determination of daptomycin by UPLC-MS/MS and its pharmacokinetic eva-luation in critically ill patients / 中国药科大学学报

@#A sensitive, selective and simple liquid chromatography tandem mass spectrometry(UPLC-MS/MS)method was developed for determining of daptomycinin human plasma and effluent. The analyte was extracted from plasma samples by SPE method, separated through a Phenomenex Kinetex C18 column(50 mm×2. 1 mm, 1. 7 μm)using isocratic mobile phase consisting of 0. 1% formic acid-acetonitile(75 ∶25), and analyzed by electro-spray ionization(ESI). The precursor to product ion transitions of m/z 810. 9→159. 1 and m/z 286. 2→217. 2 were used to measure daptomycinand the internal standard, respectively. The method was validated over a concentration range(plasma: 1-200 μg/mL, effulent: 0. 005-20 μg/mL). The intra- and inter-day precision values were less than 10% and accuracy values 90%-110%. The stability of daptomycinin human plasma and effluent under different storage conditions met the requirements of bioanalytical method. The concentration of daptomycin is significant lower in the septic shock patient, when give a dose of 6 mg/kg, the cmax and AUC0-24 h of steady state decreased by 50% and 60% respectively; the increase in capillary permeability and interstitial oedema during sepsis and septic shock may enhance drug distribution. By the way, daptomycin can be cleared via continuous veno-venous hemofiltration(CVVH)for nearly 16%. In summary, on the treatment of continuous renal replacement therapy(CRRT)in patients with septic shock with daptomycin therapy, the suggested dose should be increased, and the drug monitoring should be carried on.

Determination of paclitaxel in hyaluronic acid polymeric micelles in rat blood by protein precipitation-micelle breaking method: application to a pharmacokinetic study.

An efficient dissociation of paclitaxel (PTX) from the home-made hyaluronic acid-octadecyl (HA-C18) polymeric micelles formulation in rat blood could not be achieved using previously published PTX analytical methods. So, we intended to develop the micelle-breaking method to determine paclitaxel encapsulated in the HA-C18 polymeric micelles in blood. The pretreatment method of blood samples adopted a simple one-step protein precipitation-micelle breaking process with methanol as micelle-breaking and protein precipitant solvents for complete extraction of PTX from HA-C18 micelles in blood. The micelle breaking efficiency of methanol was as high as 97.7%. Separation was carried out by gradient elution on an Acquity UPLC BEH C18 column with a mobile phase consisting of water (containing 0.1% formic acid) and acetonitrile. A total single run time was as short as 3.0min. Detection was performed by triple-quadrupole mass spectrometry with positive electrospray ionization as source ionization in multiple-reaction monitoring mode at m/z 854.3→286.2 for PTX and m/z 808.5→527.3 for the internal standard, docetaxel. The method demonstrated good linearity at the concentrations ranging from 20 to 10,000ng/mL. The intra- and inter-day relative standard deviations were less than 9.9%. The mean extraction recoveries of PTX and IS were 94.7% and 87.5%, respectively. In summary, the methanol protein precipitation-micelle breaking method could extract PTX completely from the polymeric micelles. Finally, the method was successfully applied to a pharmacokinetic study of the home-made PTX-loaded HA-C18 polymeric micelles and Taxol solution after intravenous administration in rats.