Angiotensin-converting enzyme 2(ACE2) is not only an enzyme but also a functional receptor on cell membrane for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2). Here, the activity of ACE2 in single living ...Angiotensin-converting enzyme 2(ACE2) is not only an enzyme but also a functional receptor on cell membrane for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2). Here, the activity of ACE2 in single living cell is firstly determined using a nanokit coupled electrospray ionization mass spectrometry(nanokit-ESI-MS). Upon the insertion of a micro-capillary into the living h ACE2-CHO cell and the electrochemical sorting of the cytosol, the target ACE2 enzyme hydrolyses angiotensin II inside the capillary to generate angiotensin 1-7. After the electrospray of the mixture at the tip of the capillary, the product is differentiated from the substrate in molecular weight to achieve the detection of ACE2 activity in single cells. The further measurement illustrates that the inflammatory state of cells does not lead to the significant change of ACE2 catalytic activity, which elucidates the relationship between intracellular ACE2 activity and inflammation at single cell level. The established strategy will provide a specific analytical method for further studying the role of ACE2 in the process of virus infection, and extend the application of nanokit based single cell analysis.展开更多
Due to numerous obstacles such as complex matrices,real-time monitoring of complex reaction systems(e.g.,medicinal herb stewing system)has always been a challenge though great values for safe and rational use of drugs...Due to numerous obstacles such as complex matrices,real-time monitoring of complex reaction systems(e.g.,medicinal herb stewing system)has always been a challenge though great values for safe and rational use of drugs.Herein,facilitated by the potential ability on the tolerance of complex matrices of extractive electrospray ionization mass spectrometry,a device was established to realize continuous sampling and real-time quantitative analysis of herb stewing system for the first time.A complete analytical strategy,including data acquisition,data mining,and data evaluation was proposed and implemented with overcoming the usual difficulties in real-time mass spectrometry quantification.The complex Fuzi(the lateral root of Aconitum)-meat stewing systems were real-timely monitored in150 min by qualitative and quantitative analysis of the nine key alkaloids accurately.The results showed that the strategy worked perfectly and the toxicity of the systems were evaluated and predicated accordingly.Stewing with trotters effectively accelerated the detoxification of Fuzi soup and reduced the overall toxicity to 68%,which was recommended to be used practically for treating rheumatic arthritis and enhancing immunity.The established strategy was versatile,simple,and accurate,which would have a wide application prospect in real-time analysis and evaluation of various complex reaction systems.展开更多
A rapid and sensitive liquid chromatography tandem mass spectrometry(LC-MS/MS) method has been developed and validated for the determination of moxifloxacin(MOXI) in human plasma. After a simple protein precipitation ...A rapid and sensitive liquid chromatography tandem mass spectrometry(LC-MS/MS) method has been developed and validated for the determination of moxifloxacin(MOXI) in human plasma. After a simple protein precipitation using acetonitrile, the post treatment samples were analysed on a C18 column interfaced with a Triple Quadropole Tandem Mass Spectrometer. Positive electrospray ionization was employed as the ionization source. The mobile phase consisted of 0.1% formic acid–acetonitrile(60:40, v/v). Ciprofloxacin(CIPRO) was used as an internal standard. The analyte and internal standard(CIPRO) were monitored in the multiple reaction monitoring mode(MRM). The mass transition ion-pair has been followed as m/z 402→358.2 for MOXI and 332→288.1 for CIPRO. The method was linear in the concentration range of 25–5000 ng/mL. The lower limit of quantification was 25 ng/mL. The intra- and inter-day precision(relative standard deviation) and accuracy(relative error) values were within 12.4%. Each plasma sample was analyzed within 3 min.展开更多
During the analysis of benziamidazole-class irreversible proton pump inhibitors,an unusual mass spectral response with the mass-to-charge ratio at[Mt10]t intrigued us,as it couldn't be assigned to any literature k...During the analysis of benziamidazole-class irreversible proton pump inhibitors,an unusual mass spectral response with the mass-to-charge ratio at[Mt10]t intrigued us,as it couldn't be assigned to any literature known relevant structure,intermediate or adduct ion.Moreover,this mysterious mass pattern of[Mt10]t has been gradually observed by series of marketed proton pump inhibitors,viz.omeprazole,pantoprazole,lansoprazole and rabeprazole.All the previous attempts to isolate the corresponding component were unsuccessful.The investigation of present work addresses this kind of signal to a pyridinium thiocyanate mass spectral intermediate(10),which is the common fragment ion of series of labile aggregates.The origin of such aggregates can be traced to the reactive intermediates formed by acid-promoted degradation.These reactive intermediates tend to react with each other and give raise series of complicated aggregates systematically in a water/acetonitrile solution by electrospray ionization.The structure of the corresponding pyridinium thiocyanate species of omeprazole(10a)has been eventually characterized with the help of synthetic specimen(10a′).Our structural proposal as well as its origin was supported by in situ nuclear magnetic resonance,chemical derivatization and colorimetric experiments.展开更多
The direct coupling of solid-phase microextraction(SPME)to mass spectrometry(MS)(SPME-MS)has proven to be an effective method for the fast screening and quantitative analysis of compounds in complex matrices such as b...The direct coupling of solid-phase microextraction(SPME)to mass spectrometry(MS)(SPME-MS)has proven to be an effective method for the fast screening and quantitative analysis of compounds in complex matrices such as blood and plasma.In recent years,our lab has developed three novel SPME-MS techniques:SPME-microfluidic open interface-MS(SPME-MOI-MS),coated blade spray-MS(CBS-MS),and SPME-probe electrospray ionization-MS(SPME-PESI-MS).The fast and high-throughput nature of these SPME-MS technologies makes them attractive options for point-of-care analysis and anti-doping testing.However,all these three techniques utilize different SPME geometries and were tested with different MS instruments.Lack of comparative data makes it difficult to determine which of these methodologies is the best option for any given application.This work fills this gap by making a comprehensive comparison of these three technologies with different SPME devices including SPME fibers,CBS blades,and SPME-PESI probes and SPME-liquid chromatography-MS(SPME-LC-MS)for the analysis of drugs of abuse using the same MS instrument.Furthermore,for the first time,we developed different desorption chambers for MOI-MS for coupling with SPME fibers,CBS blades,and SPME-PESI probes,thus illustrating the universality of this approach.In total,eight analytical methods were developed,with the experimental data showing that all the SPME-based methods provided good analytical performance with R^(2)of linearities larger than 0.9925,accuracies between 81%and 118%,and good precision with an RSD%≤13%.展开更多
A direct determination method for the atrazine residue on the vegetable was developed by using desorption electrospray ionization mass spectrometry (DESI MS) without any sample pretreatment.Acetonitrile-water (1:1,v/v...A direct determination method for the atrazine residue on the vegetable was developed by using desorption electrospray ionization mass spectrometry (DESI MS) without any sample pretreatment.Acetonitrile-water (1:1,v/v),which contained 0.1% formic acid,was used as the spray solvent.The working conditions,such as ESI gas inlet pressure,ESI flow rate,ESI spray voltage,spray-to-sample distance,spray-to-cone-hole distance and the collision induced dissociation (CID) voltage for MS/MS,were optimized for both DESI and esquires 6 000 mass spectrometer.The linear range of atrazine on cabbage leaves was 25.25-2 525 pg/mm2,the R2 was 0.991 6,and the relative standard deviations were between 3.37% and 26.17%.The LOD of atrazine calculated by S/N=3 was 2.50 pg/mm2.展开更多
Puerarin,an isoflavone compound,is the bioactive component of traditional Chinese medicine.A novel dialkyl puerarin-7-yl phosphate was synthesized and investigated by positive ion electrospray ionization ion trap mass...Puerarin,an isoflavone compound,is the bioactive component of traditional Chinese medicine.A novel dialkyl puerarin-7-yl phosphate was synthesized and investigated by positive ion electrospray ionization ion trap mass spectrometry (ESI MS)in conjunction with tandem mass spectrometry.The fragmentation pathways of dialkyl puerarin-7-yl phosphates were investigated.展开更多
AIM To develop a reliable and simple method to identify important biological metabolites and relevant pathways for taurine in hepatic stellate cells(HSCs), in order to provide more data for taurine therapy.METHODS All...AIM To develop a reliable and simple method to identify important biological metabolites and relevant pathways for taurine in hepatic stellate cells(HSCs), in order to provide more data for taurine therapy.METHODS All the biological samples were analyzed by using highperformance liquid chromatography-time electrospray ionization/quadrupole-time of flight mass spectrometry. Principal component analysis and partial least squares discriminant analysis were used to identify statistically different metabolites for taurine in HSCs, and metabolomic pathway analysis was used to do pathway analysis for taurine in HSCs. The chemical structure of the related metabolites and pathways was identified by comparing the m/z ratio and ion mode with the data obtained from free online databases.RESULTS A total of 32 significant differential endogenous metabolites were identified, which may be related to the mechanism of action of taurine in HSCs. Among the seven relevant pathways identified, sphingolipid metabolism pathway, glutathione metabolism pathway and thiamine metabolism pathway were found to be the most important metabolic pathways for taurine in HSCs.CONCLUSION This study showed that there were distinct changes in biological metabolites of taurine in HSCs and three differential metabolic pathways including sphingolipid pathway, glutathione pathway and thiamine metabolism pathway might be of key importance in mediating the mechanism of action of taurine in HSCs.展开更多
Noncovalent interactions between ligands and targeting proteins are essential for understanding molecular mechanisms of proteins.In this work,we investigated the interaction of Cytochrome c(Cyt c)with maltoligosacchar...Noncovalent interactions between ligands and targeting proteins are essential for understanding molecular mechanisms of proteins.In this work,we investigated the interaction of Cytochrome c(Cyt c)with maltoligosaccharides,namely maltose(Mal Ⅱ),maltotriose(Mal Ⅲ),maltotetraose(Mal Ⅳ),maltopentaose(Mal Ⅴ),maltohexaose(Mal Ⅵ)and maltoheptaose(Mal Ⅶ).Using electrospray ionization mass spetrometry(ESI-MS)assay,the 1:1 and 1:2 complexes formed by Cyt c with maltoligosaccharide ligand were observed.The corresponding association constants were calculated according to the deconvoluted spectra.The order of the relative binding affinities of the selected oligosaccharides with Cyt c were as MalⅢ>MalⅣ>MalⅡ>MalⅤ>MalⅥ>MalⅦ.The results indicated that the stability of noncovalent protein complexes was intimately correlated to the molecular structure of bound ligand.The relevant functional groups that could form H-bonds,electrostatic or hydrophobic forces with protein’s amino residues played an important role for the stability of protein complexes.In addition,the steric structure of ligand was also critical for an appropriate interaction with the binding pocket of proteins.展开更多
The solid-phase microextraction technique quantifies analytes without considerably affecting the sample composition.Herein,a proof-of-concept study was conducted to demonstrate the use of coated probe electrospray ion...The solid-phase microextraction technique quantifies analytes without considerably affecting the sample composition.Herein,a proof-of-concept study was conducted to demonstrate the use of coated probe electrospray ionization(coated-PESI)and coated blade spray(CBS)as ambient mass spectrometry approaches for monitoring drug biotransformation.The ability of these methods was investigated for monitoring the dephosphorylation of a prodrug,combretastatin A4 phosphate(CA4P),into its active form,combretastatin A4(CA4),in a cell culture medium supplemented with fetal bovine serum.The CBS spot analysis was modified to achieve the same extraction efficiency as protein precipitation and obtained results in 7 min.Because coated-PESI performs extraction without consuming any samples,it is the preferred technique in the case of a limited sample volume.Although coated-PESI only extracts small quantities of analytes,it uses the desorption solvent volume of 5-10 pL,resulting in high sensitivity,thus allowing the detection of compounds after only 1 min of extraction.The biotransformation of CA4P into CA4 via phosphatases occurs within the simple matrix,and the proposed sample preparation techniques are suitable for monitoring the biotransformation.展开更多
The transformation of quantum dots(QDs)by organisms has attracted broad attention but remains unclear.Understanding of the metabolites helps to reveal the transformation pathway of QDs.Cd containingmetallothionein(MT)...The transformation of quantum dots(QDs)by organisms has attracted broad attention but remains unclear.Understanding of the metabolites helps to reveal the transformation pathway of QDs.Cd containingmetallothionein(MT)are the main species formed by Cd released from CdSe QDs in HepG2 cells,while speciation analysis of Cd containing MTs remains a challenge because MTs has several subisoforms and can bind with several metals.Herein,we built a hyphenated platform for speciation analysis of QDs in HepG2 cells after treatment with CdSe/ZnS QDs.The Cd-containing MTs were separated in reversed phase high performance liquid chromatography(RP-HPLC)and subsequently online detected by inductively coupled plasma mass spectrometry(ICP-MS)and electrospray ionization quadrupole time-of-flight mass spectrometry(ESI-Q-TOF-MS)parallelly.Four groups of Cd-containing metabolites were found by detecting Cd in ICP-MS.Their structures were identified in ESI-Q-TOF-MS and further confirmed with standards of four subisoforms of MT,including N-terminal acetylation MT2a,N-terminal acetylation MT1e,N-terminal acetylation MT1g and MT1m.Each group of them contains various stoichiometry of Cd/Zn.The metabolites of QDs remain same while the concentrations of each metabolite and its stoichiometry of Cd/Zn vary for different incubation concentration/time.This work provides a new parallel hyphenation technique of HPLC-ICP-MS/ESI-MS with high separation resolution and powerful detection ability,and the obtained results provide detailed metabolism information of QDs in HepG2 cells after treatment of CdSe/ZnS QDs,contributing to deep exploration of the functional mechanisms of QDs in organisms.展开更多
Valence-bound molecular anions with polar neutral cores(μ>2.5 D)can support highly diffuse dipole-bound states(DBSs)as electronically excited states just below the detachment threshold.Such weakly bound nonvalence...Valence-bound molecular anions with polar neutral cores(μ>2.5 D)can support highly diffuse dipole-bound states(DBSs)as electronically excited states just below the detachment threshold.Such weakly bound nonvalence excited states have little influence on the structure of the neutral core,and they usually have the same vibrational frequencies.DBSs can be systematically searched using photodetachment spectroscopy(PDS),which can yield the binding energies of the DBSs,the electron detachment threshold of the anion,and above-threshold vibrational levels of the DBSs(Feshbach resonances).We have shown that the combination of PDS and resonant photoelectron spectroscopy(rPES)at the Feshbach resonances is a powerful approach to obtain rich vibrational information for complex molecular radicals.A prerequisite for this technique is to produce vibrationally cold anions,made possible by a cryogenically controlled Paul trap.In this article,we report a PDS and rPES study of cold para-ethylphenolate anions(p-EP^(-)).The electron affinity of the p-EP radical is measured to be 17425±3 cm^(-1)(2.1604±0.0004 eV),and a DBS is found at 145 cm^(-1) below the detachment threshold of p-EP^(-).Thirty-four vibrational levels are observed for the DBS,including two bound levels and 32 Feshbach resonances.Frequencies for 17 vibrational modes of the p-EP radical are measured from the combination of PDS and rPES,including six symmetry-forbidden modes with A″symmetry.The current study confirms again the power of combining cryogenic ion cooling with PDS and highresolution rPES to obtain spectroscopic information on complex molecular radicals.展开更多
Objective: The present study aimed to quantify and identify the bioactive compounds of the Arbutus unedo L. leaves in order to evaluate both their antioxidant properties and litholytic activities against calcium oxala...Objective: The present study aimed to quantify and identify the bioactive compounds of the Arbutus unedo L. leaves in order to evaluate both their antioxidant properties and litholytic activities against calcium oxalate stones.Methods: This survey was carried out using hydroalcoholic extract(E.FA) and infusion(I.FA) of A. unedo leaves. The quantification of phenolic compounds, flavonoids, flavonols and anthocyanins was done by spectrophotometric methods and identification of chemical components was performed by ultraperformance liquid chromatography with photodiode array and electrospray ionization tandem mass spectrometry. Antioxidant activity was measured using the 1,1-diphenyl-2-picrylhydrazyl(DPPH)method and by the ferric reducing/antioxidant power(FRAP) assay. Litholytic activity of E.FA and I.FA was studied using a special model that resembles circuitry of the urinary system.Results: E.FA showed greater antioxidant efficacy than I.FA(P < 0.05). Its higher efficiency was shown via the values of median inhibitory concentration, which was close to(76.14 ± 0.91) mg/mL for E.FA versus(202.64 ± 5.77) lg/mL for I.FA using the DPPH method, and(53.77 ± 0.81) lg/mL for E.FA versus(236.86 ± 31.90) lg/mL for I.FA, using FRAP method. I.FA exhibited significantly higher litholytic activity compared to E.FA(P < 0.05), with dissolution values of 31.03% ± 0.63% versus 14.55% ± 0.65%, respectively.Conclusion: Overall, the results suggest that the A. unedo is rich in bioactive compounds, and possesses antioxidant and litholitic abilities that are worthy of further study.展开更多
基金supported by Ministry of Science and Technology of China(No.2017YFA0700500)the National Natural Science Foundation of China(Nos.22025403 and 21974060)+1 种基金Kuanren Talents Program of the Second Affiliated Hospital of Chongqing Medical UniversityYoung and Middle-aged Senior Medical Talents Studio of Chongqing。
文摘Angiotensin-converting enzyme 2(ACE2) is not only an enzyme but also a functional receptor on cell membrane for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2). Here, the activity of ACE2 in single living cell is firstly determined using a nanokit coupled electrospray ionization mass spectrometry(nanokit-ESI-MS). Upon the insertion of a micro-capillary into the living h ACE2-CHO cell and the electrochemical sorting of the cytosol, the target ACE2 enzyme hydrolyses angiotensin II inside the capillary to generate angiotensin 1-7. After the electrospray of the mixture at the tip of the capillary, the product is differentiated from the substrate in molecular weight to achieve the detection of ACE2 activity in single cells. The further measurement illustrates that the inflammatory state of cells does not lead to the significant change of ACE2 catalytic activity, which elucidates the relationship between intracellular ACE2 activity and inflammation at single cell level. The established strategy will provide a specific analytical method for further studying the role of ACE2 in the process of virus infection, and extend the application of nanokit based single cell analysis.
基金supported by the National Natural Science Foundation of China(No.81603293)Young Elite Scientist Sponsorship Program by China Association for Science and Technology(No.CACM-2018-QNRC1-04,China)+1 种基金the Fundamental Research Funds for the Central Public Welfare Research Institutes(No.ZZ13-YQ-090,China)Key Project at Central Government Level:The ability establishment of sustainable use for valuable Chinese medicine resources(No.2060302,China)
文摘Due to numerous obstacles such as complex matrices,real-time monitoring of complex reaction systems(e.g.,medicinal herb stewing system)has always been a challenge though great values for safe and rational use of drugs.Herein,facilitated by the potential ability on the tolerance of complex matrices of extractive electrospray ionization mass spectrometry,a device was established to realize continuous sampling and real-time quantitative analysis of herb stewing system for the first time.A complete analytical strategy,including data acquisition,data mining,and data evaluation was proposed and implemented with overcoming the usual difficulties in real-time mass spectrometry quantification.The complex Fuzi(the lateral root of Aconitum)-meat stewing systems were real-timely monitored in150 min by qualitative and quantitative analysis of the nine key alkaloids accurately.The results showed that the strategy worked perfectly and the toxicity of the systems were evaluated and predicated accordingly.Stewing with trotters effectively accelerated the detoxification of Fuzi soup and reduced the overall toxicity to 68%,which was recommended to be used practically for treating rheumatic arthritis and enhancing immunity.The established strategy was versatile,simple,and accurate,which would have a wide application prospect in real-time analysis and evaluation of various complex reaction systems.
文摘A rapid and sensitive liquid chromatography tandem mass spectrometry(LC-MS/MS) method has been developed and validated for the determination of moxifloxacin(MOXI) in human plasma. After a simple protein precipitation using acetonitrile, the post treatment samples were analysed on a C18 column interfaced with a Triple Quadropole Tandem Mass Spectrometer. Positive electrospray ionization was employed as the ionization source. The mobile phase consisted of 0.1% formic acid–acetonitrile(60:40, v/v). Ciprofloxacin(CIPRO) was used as an internal standard. The analyte and internal standard(CIPRO) were monitored in the multiple reaction monitoring mode(MRM). The mass transition ion-pair has been followed as m/z 402→358.2 for MOXI and 332→288.1 for CIPRO. The method was linear in the concentration range of 25–5000 ng/mL. The lower limit of quantification was 25 ng/mL. The intra- and inter-day precision(relative standard deviation) and accuracy(relative error) values were within 12.4%. Each plasma sample was analyzed within 3 min.
基金supported by the National Natural Science Foundation of China(Grant Nos.:82030107 and 81872831)the National Science and Technology Major Projects for significant new drugs creation of the 13th five-year plan(Grant Nos.:2017ZX09101001 and 2018ZX09721002007).
文摘During the analysis of benziamidazole-class irreversible proton pump inhibitors,an unusual mass spectral response with the mass-to-charge ratio at[Mt10]t intrigued us,as it couldn't be assigned to any literature known relevant structure,intermediate or adduct ion.Moreover,this mysterious mass pattern of[Mt10]t has been gradually observed by series of marketed proton pump inhibitors,viz.omeprazole,pantoprazole,lansoprazole and rabeprazole.All the previous attempts to isolate the corresponding component were unsuccessful.The investigation of present work addresses this kind of signal to a pyridinium thiocyanate mass spectral intermediate(10),which is the common fragment ion of series of labile aggregates.The origin of such aggregates can be traced to the reactive intermediates formed by acid-promoted degradation.These reactive intermediates tend to react with each other and give raise series of complicated aggregates systematically in a water/acetonitrile solution by electrospray ionization.The structure of the corresponding pyridinium thiocyanate species of omeprazole(10a)has been eventually characterized with the help of synthetic specimen(10a′).Our structural proposal as well as its origin was supported by in situ nuclear magnetic resonance,chemical derivatization and colorimetric experiments.
基金the National Science Centre,Poland(Grant No.:2020/04/X/NZ9/01281).
文摘The direct coupling of solid-phase microextraction(SPME)to mass spectrometry(MS)(SPME-MS)has proven to be an effective method for the fast screening and quantitative analysis of compounds in complex matrices such as blood and plasma.In recent years,our lab has developed three novel SPME-MS techniques:SPME-microfluidic open interface-MS(SPME-MOI-MS),coated blade spray-MS(CBS-MS),and SPME-probe electrospray ionization-MS(SPME-PESI-MS).The fast and high-throughput nature of these SPME-MS technologies makes them attractive options for point-of-care analysis and anti-doping testing.However,all these three techniques utilize different SPME geometries and were tested with different MS instruments.Lack of comparative data makes it difficult to determine which of these methodologies is the best option for any given application.This work fills this gap by making a comprehensive comparison of these three technologies with different SPME devices including SPME fibers,CBS blades,and SPME-PESI probes and SPME-liquid chromatography-MS(SPME-LC-MS)for the analysis of drugs of abuse using the same MS instrument.Furthermore,for the first time,we developed different desorption chambers for MOI-MS for coupling with SPME fibers,CBS blades,and SPME-PESI probes,thus illustrating the universality of this approach.In total,eight analytical methods were developed,with the experimental data showing that all the SPME-based methods provided good analytical performance with R^(2)of linearities larger than 0.9925,accuracies between 81%and 118%,and good precision with an RSD%≤13%.
文摘A direct determination method for the atrazine residue on the vegetable was developed by using desorption electrospray ionization mass spectrometry (DESI MS) without any sample pretreatment.Acetonitrile-water (1:1,v/v),which contained 0.1% formic acid,was used as the spray solvent.The working conditions,such as ESI gas inlet pressure,ESI flow rate,ESI spray voltage,spray-to-sample distance,spray-to-cone-hole distance and the collision induced dissociation (CID) voltage for MS/MS,were optimized for both DESI and esquires 6 000 mass spectrometer.The linear range of atrazine on cabbage leaves was 25.25-2 525 pg/mm2,the R2 was 0.991 6,and the relative standard deviations were between 3.37% and 26.17%.The LOD of atrazine calculated by S/N=3 was 2.50 pg/mm2.
文摘Puerarin,an isoflavone compound,is the bioactive component of traditional Chinese medicine.A novel dialkyl puerarin-7-yl phosphate was synthesized and investigated by positive ion electrospray ionization ion trap mass spectrometry (ESI MS)in conjunction with tandem mass spectrometry.The fragmentation pathways of dialkyl puerarin-7-yl phosphates were investigated.
基金Supported by National Natural Science Foundation of China,No.81360595 and No.81360532Guangxi Natural Science Foundation Program,No.2014GXNSFDA118027+1 种基金Bagui Scholars Foundation Program of GuangxiSpecial-term Experts Foundation Program of Guangxi
文摘AIM To develop a reliable and simple method to identify important biological metabolites and relevant pathways for taurine in hepatic stellate cells(HSCs), in order to provide more data for taurine therapy.METHODS All the biological samples were analyzed by using highperformance liquid chromatography-time electrospray ionization/quadrupole-time of flight mass spectrometry. Principal component analysis and partial least squares discriminant analysis were used to identify statistically different metabolites for taurine in HSCs, and metabolomic pathway analysis was used to do pathway analysis for taurine in HSCs. The chemical structure of the related metabolites and pathways was identified by comparing the m/z ratio and ion mode with the data obtained from free online databases.RESULTS A total of 32 significant differential endogenous metabolites were identified, which may be related to the mechanism of action of taurine in HSCs. Among the seven relevant pathways identified, sphingolipid metabolism pathway, glutathione metabolism pathway and thiamine metabolism pathway were found to be the most important metabolic pathways for taurine in HSCs.CONCLUSION This study showed that there were distinct changes in biological metabolites of taurine in HSCs and three differential metabolic pathways including sphingolipid pathway, glutathione pathway and thiamine metabolism pathway might be of key importance in mediating the mechanism of action of taurine in HSCs.
基金supported by the National Natural Science Foundation of China(Grant No.21675176)the Natural Science Foundation of Hubei Province(Grant No.2014CFA025)the Preferred Research Foundation for the Returned Overseas Scholars from Ministry of Human Resources and Social Security of the People’s Republic of China(Grant No.BZY14036)for financial supports.
文摘Noncovalent interactions between ligands and targeting proteins are essential for understanding molecular mechanisms of proteins.In this work,we investigated the interaction of Cytochrome c(Cyt c)with maltoligosaccharides,namely maltose(Mal Ⅱ),maltotriose(Mal Ⅲ),maltotetraose(Mal Ⅳ),maltopentaose(Mal Ⅴ),maltohexaose(Mal Ⅵ)and maltoheptaose(Mal Ⅶ).Using electrospray ionization mass spetrometry(ESI-MS)assay,the 1:1 and 1:2 complexes formed by Cyt c with maltoligosaccharide ligand were observed.The corresponding association constants were calculated according to the deconvoluted spectra.The order of the relative binding affinities of the selected oligosaccharides with Cyt c were as MalⅢ>MalⅣ>MalⅡ>MalⅤ>MalⅥ>MalⅦ.The results indicated that the stability of noncovalent protein complexes was intimately correlated to the molecular structure of bound ligand.The relevant functional groups that could form H-bonds,electrostatic or hydrophobic forces with protein’s amino residues played an important role for the stability of protein complexes.In addition,the steric structure of ligand was also critical for an appropriate interaction with the binding pocket of proteins.
基金supported by Shimadzu Scientific Instruments(Columbia,MD,USA)and Canada’s National Science and Engineering Research Council-Industrial Research Chair(NSERC-IRC)program,grant number IRCPJ 184412-15
文摘The solid-phase microextraction technique quantifies analytes without considerably affecting the sample composition.Herein,a proof-of-concept study was conducted to demonstrate the use of coated probe electrospray ionization(coated-PESI)and coated blade spray(CBS)as ambient mass spectrometry approaches for monitoring drug biotransformation.The ability of these methods was investigated for monitoring the dephosphorylation of a prodrug,combretastatin A4 phosphate(CA4P),into its active form,combretastatin A4(CA4),in a cell culture medium supplemented with fetal bovine serum.The CBS spot analysis was modified to achieve the same extraction efficiency as protein precipitation and obtained results in 7 min.Because coated-PESI performs extraction without consuming any samples,it is the preferred technique in the case of a limited sample volume.Although coated-PESI only extracts small quantities of analytes,it uses the desorption solvent volume of 5-10 pL,resulting in high sensitivity,thus allowing the detection of compounds after only 1 min of extraction.The biotransformation of CA4P into CA4 via phosphatases occurs within the simple matrix,and the proposed sample preparation techniques are suitable for monitoring the biotransformation.
基金The financial support from the National Natural Science Foundation of China(Nos.21575107,21775113,21575108)the Science Fund for Creative Research Groups of NSFC(No.20921062)the Fundamental Research Funds for the Central Universities(No.114009)。
文摘The transformation of quantum dots(QDs)by organisms has attracted broad attention but remains unclear.Understanding of the metabolites helps to reveal the transformation pathway of QDs.Cd containingmetallothionein(MT)are the main species formed by Cd released from CdSe QDs in HepG2 cells,while speciation analysis of Cd containing MTs remains a challenge because MTs has several subisoforms and can bind with several metals.Herein,we built a hyphenated platform for speciation analysis of QDs in HepG2 cells after treatment with CdSe/ZnS QDs.The Cd-containing MTs were separated in reversed phase high performance liquid chromatography(RP-HPLC)and subsequently online detected by inductively coupled plasma mass spectrometry(ICP-MS)and electrospray ionization quadrupole time-of-flight mass spectrometry(ESI-Q-TOF-MS)parallelly.Four groups of Cd-containing metabolites were found by detecting Cd in ICP-MS.Their structures were identified in ESI-Q-TOF-MS and further confirmed with standards of four subisoforms of MT,including N-terminal acetylation MT2a,N-terminal acetylation MT1e,N-terminal acetylation MT1g and MT1m.Each group of them contains various stoichiometry of Cd/Zn.The metabolites of QDs remain same while the concentrations of each metabolite and its stoichiometry of Cd/Zn vary for different incubation concentration/time.This work provides a new parallel hyphenation technique of HPLC-ICP-MS/ESI-MS with high separation resolution and powerful detection ability,and the obtained results provide detailed metabolism information of QDs in HepG2 cells after treatment of CdSe/ZnS QDs,contributing to deep exploration of the functional mechanisms of QDs in organisms.
基金supported by the Department of Energy,Office of Basic Energy Sciences,Chemical Sciences,Geosciences,and Biosciences Division under Grant DE-SC0018679.
文摘Valence-bound molecular anions with polar neutral cores(μ>2.5 D)can support highly diffuse dipole-bound states(DBSs)as electronically excited states just below the detachment threshold.Such weakly bound nonvalence excited states have little influence on the structure of the neutral core,and they usually have the same vibrational frequencies.DBSs can be systematically searched using photodetachment spectroscopy(PDS),which can yield the binding energies of the DBSs,the electron detachment threshold of the anion,and above-threshold vibrational levels of the DBSs(Feshbach resonances).We have shown that the combination of PDS and resonant photoelectron spectroscopy(rPES)at the Feshbach resonances is a powerful approach to obtain rich vibrational information for complex molecular radicals.A prerequisite for this technique is to produce vibrationally cold anions,made possible by a cryogenically controlled Paul trap.In this article,we report a PDS and rPES study of cold para-ethylphenolate anions(p-EP^(-)).The electron affinity of the p-EP radical is measured to be 17425±3 cm^(-1)(2.1604±0.0004 eV),and a DBS is found at 145 cm^(-1) below the detachment threshold of p-EP^(-).Thirty-four vibrational levels are observed for the DBS,including two bound levels and 32 Feshbach resonances.Frequencies for 17 vibrational modes of the p-EP radical are measured from the combination of PDS and rPES,including six symmetry-forbidden modes with A″symmetry.The current study confirms again the power of combining cryogenic ion cooling with PDS and highresolution rPES to obtain spectroscopic information on complex molecular radicals.
文摘Objective: The present study aimed to quantify and identify the bioactive compounds of the Arbutus unedo L. leaves in order to evaluate both their antioxidant properties and litholytic activities against calcium oxalate stones.Methods: This survey was carried out using hydroalcoholic extract(E.FA) and infusion(I.FA) of A. unedo leaves. The quantification of phenolic compounds, flavonoids, flavonols and anthocyanins was done by spectrophotometric methods and identification of chemical components was performed by ultraperformance liquid chromatography with photodiode array and electrospray ionization tandem mass spectrometry. Antioxidant activity was measured using the 1,1-diphenyl-2-picrylhydrazyl(DPPH)method and by the ferric reducing/antioxidant power(FRAP) assay. Litholytic activity of E.FA and I.FA was studied using a special model that resembles circuitry of the urinary system.Results: E.FA showed greater antioxidant efficacy than I.FA(P < 0.05). Its higher efficiency was shown via the values of median inhibitory concentration, which was close to(76.14 ± 0.91) mg/mL for E.FA versus(202.64 ± 5.77) lg/mL for I.FA using the DPPH method, and(53.77 ± 0.81) lg/mL for E.FA versus(236.86 ± 31.90) lg/mL for I.FA, using FRAP method. I.FA exhibited significantly higher litholytic activity compared to E.FA(P < 0.05), with dissolution values of 31.03% ± 0.63% versus 14.55% ± 0.65%, respectively.Conclusion: Overall, the results suggest that the A. unedo is rich in bioactive compounds, and possesses antioxidant and litholitic abilities that are worthy of further study.
