The development and delivery of high quality therapeutic products necessitates the need for highthrough-put (HTP) process development tools. Traditionally, these works requires a combination of shake flask and small-s...The development and delivery of high quality therapeutic products necessitates the need for highthrough-put (HTP) process development tools. Traditionally, these works requires a combination of shake flask and small-scale stirred tank bioreactor (STR) which are labor and resource intensive and time-consuming. Here we demonstrate a strategy for rapid and robust cell culture process development by evaluating and implementing the use of a new HTP disposable micro bioreactor (MBR) called AMBRTM system (Advanced Microscale Bioreactor) that has the capabilities for automated sampling, feed addition, pH, dissolved oxygen (DO), gassing and agitation controls. In these studies the performance of two monoclonal antibody (MAb) producing cell lines (MAb1 and MAb2) was evaluated both in the AMBR system and 3-L STR. We demonstrated that cell culture performance (growth and viability, production titer and product quality) were similar in both vessel systems. Furthermore, process control and feed optimization were demonstrated in an additional cell line (MAb3) in the disposable MBR and its performance confirmed at STR scale. The results indicate that the AMBR system can be used to streamline the process development effort and facilitate a rapid and robust cell culture process development effort for MAb programs in a HTP manner.展开更多
The present method gives a detailed description for the development and validation of a simple stability indicating reverse phase liquid chromatographic method for 10-hydroxycamptothecin(10-HCTN) in the presence of it...The present method gives a detailed description for the development and validation of a simple stability indicating reverse phase liquid chromatographic method for 10-hydroxycamptothecin(10-HCTN) in the presence of its impurities namely Imp A and Imp B along with degradation products generated from forced degradation studies. The drug was subjected to stress conditions of hydrolysis (acid, base and neutral), oxidative, photolytic and thermal stress degradation. Degradation was observed when subjected to treatment with peroxides or under conditions normally used for typical acid and base hydrolysis. The drug was found to be stable under other stress conditions attempted such as photolytic and thermal. Successful separation and isolation of the drug from related impurities and degradation products formed under stress conditions was achieved on an Inertsil ODS-3V (250 mm × 4.6 mm, 5 μm) column using a phosphate buffer, acetonitrile, methanol and Nanopure water. The developed HPLC method was validated with respect to specificity, linearity, accuracy, precision, sensitivity, robustness and solution stability. The assay method was found to be linear in the range of 0.16 mg/mL to 0.24 mg/mL with a correlation coefficient of 0.999 and the linearity of the impurities was established from 0.02% (LOQ) to 0.3%. Recoveries of assay and impurities were found between 99.4% and 100.3%. The developed HPLC method can be used to determine the related substances and assay determinations of 10-HCTN and also to evaluate the quality and long term stability of production samples.展开更多
The present method provides the detailed description of development and validation of a simple stability indicating re- verse phase column liquid chromatographic method for Olmesartan in the presence of its impurities...The present method provides the detailed description of development and validation of a simple stability indicating re- verse phase column liquid chromatographic method for Olmesartan in the presence of its impurities namely Imp-A, Imp-B, Imp-C, Imp-D, Imp-E, Imp-F and Imp-G and degradation products generated from forced degradation studies. The drug substance was subjected to stress conditions of aqueous hydrolysis, Oxidative, photolytic and thermal stress degradation. The degradation of Olmesartan was observed under acid hydrolysis, base hydrolysis and peroxide. The drug was found to be stable to other stress conditions attempted. Successful separation of the drug from synthetic impu- rities and degradation products formed under stress conditions was achieved on symmetry C18, 150 mm × 4.6 mm, 5μ column using a phosphate buffer, Acetonitrile and Milli Q water. The developed LC method was validated with respect to specificity, linearity, accuracy, precision, raggedness and robustness. The assay method was found to be linear in the range of 250 μg?mL–1 to with 1000 μg?mL–1 correlation coefficient of 0.9999 and the linearity of the impurities was es- tablished from LOQ to 0.4%. Recoveries of assay and impurities were found between 98.5% and 101.2%. The devel- oped LC method to determine the related substances and assay determinations of Olmesartan can be used to evaluate the quality of regular production samples and stability samples. To best of our knowledge, the validated stability indi- cating LC method which separates all the impurities disclosed in this investigation was not published elsewhere.展开更多
To explore the relationship of microplastic pollution in different media in marine environment,microplastics in the surface seawater and sediments of Laizhou Bay,Bohai Sea,North China,were studied.Seawater samples wer...To explore the relationship of microplastic pollution in different media in marine environment,microplastics in the surface seawater and sediments of Laizhou Bay,Bohai Sea,North China,were studied.Seawater samples were collected using a pre-concentrator equipped with a 20-μm mesh size sieve,and sediment samples were collected by a box sampler.The shape,color,size,and type of microplastics were obtained by a stereomicroscope and a Fourier transform infrared spectrometer(ATR-μ-FT-IR).Results show that the abundance of microplastics in the surface seawater of Laizhou Bay was 858.3±573.2 items/m~3,and that of microplastics in sediments was 151.0±77.4 items/kg dry weight(d.w.)The microplastics in seawater and sediments were mainly fibrous.Meanwhile,the microplastics in seawater were mainly transparent,and those in sediments were transparent and blue.The highest proportion of microplastics in seawater was rayon(77.48%),followed by polyethylene terephthalate(PET,13.17%).The highest proportion of microplastics in sediments was rayon(73.66%),followed by PET(8.90%).The size of microplastics in 1000-2000μm accounted for the largest proportion of 28.54%in seawater,while that in 500-1000μm took 27.93%in sediment.Microplastics in seawater and sediment showed medium-level pollution.In seawater,microplastic abundance was higher in offshore and nearshore areas of Weifang.In sediment,microplastic abundance was higher in offshore and nearshore areas of Dongying.The results of the principal component analysis(PCA)indicated that microplastics in sediment exhibited greater stability compared to those in seawater.The microplastics in seawater and sediment show a positive correlation in terms of shape and plastic type,while exhibiting a negative correlation in terms of color.Overall,microplastics in sediments were smaller in size,and those in seawater and sediments had consistent size distribution characteristics in space.展开更多
Decabromodiphenyl ethane(DBDPE)is widely used as an additive flame retardant and has led to global pollution.Its has a large molecular mass and is prone to debromination and degradation under photothermal conditions,r...Decabromodiphenyl ethane(DBDPE)is widely used as an additive flame retardant and has led to global pollution.Its has a large molecular mass and is prone to debromination and degradation under photothermal conditions,resulting in smaller homologous compounds.Due to the lack of standard substances for debromination products,the in-depth study of DBDPE environmental geochemical behavior through debromination conversion has been hindered.Therefore,based on DBDPE photodegradation experiment,this study first analyzed and identified the brominated products of DBDPE using high-performance liquid chromatography-atmospheric pressure photoionization-time of flight mass spectrometry(HPLC-APPI-TOF/MS).Four debromination products-nonabromodiphenyl ethane(nonaBDPE),octabromodiphenyl ethane(octa-BDPE),heptabromodiphenyl ethane(hepta-BDPE)and hexabromodiphenyl ethane(hexa-BDPE)are identified based on the characteristic ion peak of[M-Br+O]^(-) in negative ion mode.Subsequently,using methanol as the mobile phase,four debromination products of DBDPE were separated and purified with a semi-preparative high-performance liquid chromatography(SP-HPLC)system equipped with an Agilent Zorbax Eclipse PAH column(4.6 mm×250 mm,5μm).The first-time acquisition of hexa-BDPE(60.00μg),octa-BDPE(19.40μg),hepta-BDPE(31.20μg)and octa-BDPE(isomer,45.20μg)with purity exceeding 90%has been achieved.Among them,the purity of one hepta-BDPE monomer is as high as 98.91%.This study indicates that based on photodegradation experiments,the combination of HPLC-APPI-TOF/MS and SP-HPLC techniques can rapidly identify and prepare DBDPE debrominated products.This approach meets the requirements for preliminary research on the pollution characteristics of DBDPE debrominated compounds and offers a feasible solution for the preparation of standard reference materials for emerging pollutants.展开更多
Hierarchical clustering analysis and principal component analysis （PCA） methods were used to assess the similarities and dissimilarities of the entire Excitation-emission matrix spectroscopy （EEMs） data sets of sa...Hierarchical clustering analysis and principal component analysis （PCA） methods were used to assess the similarities and dissimilarities of the entire Excitation-emission matrix spectroscopy （EEMs） data sets of samples collected from Jiaozhou Bay, China. The results demonstrate that multivariate analysis facilitates the complex data treatment and spectral sorting processes, and also enhances the probability to reveal otherwise hidden information concerning the chemical characteristics of the dissolved organic matter （DOM）. The distribution of different water samples as revealed by multivariate results has been used to track the movement of DOM material in the study area, and the interpretation is supported by the results obtained from the numerical simulation model of substance tracing technique, which show that the substance discharged by Haibo River can be distributed in Jiaozhou Bay.展开更多
Budesonide is a corticosteroid used for the treatment of asthma via various matrices and inhalation mechanisms. An unknown peak of Budesonide aqueous formulation has been investigated during stability study wherein th...Budesonide is a corticosteroid used for the treatment of asthma via various matrices and inhalation mechanisms. An unknown peak of Budesonide aqueous formulation has been investigated during stability study wherein the impurity level observed around 0.1% well below the threshold 0.5%. The approach to identify anonymous species was adopted as first to generate the impurity in sample, isolate, enrich and was subjected to LC-MS/MS and NMR for spectral studies. Based on the spectral data the anonymous species were identified as a “Lumibudesonide’’ ((5aR,5bS,5cS,6S,7aS,7bS,10aR,11aS,11bS)-6-hydroxy-7b-(2-hydroxyacetyl)-5b,7a-dimethyl-9-propyl 1,5a,5b,5c,6,7,7a,7b,10a,11,11a,11b dodecahydrocyclopenta[2'',3'']cyclopropa [1'',2'':3', 4']benzo [1',2':4,5]indeno [1,2-d][1,3]dioxol-5(2H)-one), which is observed in photolysis of Budesonide.展开更多
Severe acute respiratory syndrome-associated coronavirus 2 is a major global health issue and is driving the need for new therapeutics.The surface spike protein,which plays a central role in virus infection,is current...Severe acute respiratory syndrome-associated coronavirus 2 is a major global health issue and is driving the need for new therapeutics.The surface spike protein,which plays a central role in virus infection,is currently the target for vaccines and neutralizing treatments.The emergence of novel variants with multiple mutations in the spike protein may reduce the effectiveness of neutralizing antibodies by altering the binding activity of the protein with angiotensin-converting enzyme 2(ACE2).To understand the impact of spike protein mutations on the binding interactions required for virus infection and the effectiveness of neutralizing monoclonal antibody(mAb)therapies,the binding activities of the original spike protein receptor binding domain(RBD)sequence and the reported spike protein variants were investigated using surface plasmon resonance.In addition,the interactions of the ACE2 receptor,an antispike mAb(mAb1),a neutralizing mAb(mAb2),the original spike RBD sequence,and mutants D614G,N501Y,N439K,Y453F,and E484K were assessed.Compared to the original RBD,the Y453F and N501Y mutants displayed a significant increase in ACE2 binding affinity,whereas D614G had a substantial reduction in binding affinity.All mAb-RBD mutant proteins displayed a reduction in binding affinities relative to the original RBD,except for the E484K-mAb1 interaction.The potential neutralizing capability of mAb1 and mAb2 was investigated.Accordingly,mAb1 failed to inhibit the ACE2-RBD interaction while mAb2 inhibited the ACE2-RBD interactions for all RBD mutants,except mutant E484K,which only displayed partial blocking.展开更多
A stability indicating LC method was developed for the simultaneous determination of Amlodipine and Benazepril capsules in pharmaceutical dosage form. Efficient chromatographic separation was achieved on Symmetry C18 ...A stability indicating LC method was developed for the simultaneous determination of Amlodipine and Benazepril capsules in pharmaceutical dosage form. Efficient chromatographic separation was achieved on Symmetry C18 stationary phase with simple combination of amobile phase containing 750 mL of DI Water, 250 mL of Acetonitrile and 2 mL of Octylamine into suitable container with adjusted pH to 2.50 ± 0.05 with the aid of Ortho phosphoric acid delivered in an isocratic mode and quantification was carried out using UV detection at 240 nm at a flow rate of 1.0 mL·min-1 with an injection volume of 20 μl and ambient column temperature. This method is capable to detect both the drug components of Amlodipine and Benazepril in presence of their degradation products (Amlodipine Imp-A and Benazepril Impurity-C) with a detection level of 0.05%. Amlodipine/Benazepril in their combination drug product were exposed to thermal, photolytic, hydrolytic and oxidative stress conditions, and the samples were analysed. Peak homogeneity data of Amlodipine and Benazeprilis were obtained using PDA detector, in the stressed sample chromatograms, demonstrating the specificity. The method shows excellent linearity over a range of 0.05%-2.0% for Amlodipine, Amlodipine Impurity-A and 0.05%-5.0% for Benazepril and Benazepril Impurity-C. The correlation coefficient for Amlodipine and Benazepril is 1. The relative standard deviation was always less than 2%. The proposed method was found to be suitable and accurate for quantitative determination and the stability study of Amlodipine and Benazepril in pharmaceutical preparations. The developed HPLC method was validated with respect to linearity & range, accuracy, precision and robustness.展开更多
BACKGROUND Mixed neuroendocrine non-neuroendocrine neoplasm(MiNEN)is a rare diagnosis,mainly encountered in the gastro-entero-pancreatic tract.There is limited knowledge of its epidemiology,prognosis and biology,and t...BACKGROUND Mixed neuroendocrine non-neuroendocrine neoplasm(MiNEN)is a rare diagnosis,mainly encountered in the gastro-entero-pancreatic tract.There is limited knowledge of its epidemiology,prognosis and biology,and the best management for affected patients is still to be defined.AIM To investigate clinical-pathological characteristics,treatment modalities and survival outcomes of a retrospective cohort of patients with a diagnosis of MiNEN.METHODS Consecutive patients with a histologically proven diagnosis of MiNEN were identified at 5 European centres.Patient data were retrospectively collected from medical records.Pathological samples were reviewed to ascertain compliance with the 2017 World Health Organisation definition of MiNEN.Tumour responses to systemic treatment were assessed according to the Response Evaluation Criteria in Solid Tumours 1.1.Kaplan-Meier analysis was applied to estimate survival outcomes.Associations between clinical-pathological characteristics and survival outcomes were explored using Log-rank test for equality of survivors functions(univariate)and Cox-regression analysis(multivariable).RESULTS Sixty-nine consecutive patients identified;Median age at diagnosis:64 years.Males:63.8%.Localised disease(curable):53.6%.Commonest sites of origin:colon-rectum(43.5%)and oesophagus/oesophagogastric junction(15.9%).The neuroendocrine component was;predominant in 58.6%,poorly differentiated in 86.3%,and large cell in 81.25%,of cases analysed.Most distant metastases analysed(73.4%)were occupied only by a poorly differentiated neuroendocrine component.Ninety-four percent of patients with localised disease underwent curative surgery;53%also received perioperative treatment,most often in line with protocols for adenocarcinomas from the same sites of origin.Chemotherapy was offered to most patients(68.1%)with advanced disease,and followed protocols for pure neuroendocrine carcinomas or adenocarcinomas in equal proportion.In localised cases,median recurrence free survival(RFS);14.0 months(95%CI:9.2-24.4),and median overall survival(OS):28.6 months(95%CI:18.3-41.1).On univariate analysis,receipt of perioperative treatment(vs surgery alone)did not improve RFS(P=0.375),or OS(P=0.240).In advanced cases,median progression free survival(PFS);5.6 months(95%CI:4.4-7.4),and median OS;9.0 months(95%CI:5.2-13.4).On univariate analysis,receipt of palliative active treatment(vs best supportive care)prolonged PFS and OS(both,P<0.001).CONCLUSION MiNEN is most commonly driven by a poorly differentiated neuroendocrine component,and has poor prognosis.Advances in its biological understanding are needed to identify effective treatments and improve patient outcomes.展开更多
Monitoring of host cell proteins(HCPs)during the manufacturing of monoclonal antibodies(mAb)has become a critical requirement to provide effective and safe drug products.Enzyme-linked immunosorbent assays are still th...Monitoring of host cell proteins(HCPs)during the manufacturing of monoclonal antibodies(mAb)has become a critical requirement to provide effective and safe drug products.Enzyme-linked immunosorbent assays are still the gold standard methods for the quantification of protein impurities.However,this technique has several limitations and does,among others,not enable the precise identification of proteins.In this context,mass spectrometry(MS)became an alternative and orthogonal method that delivers qualitative and quantitative information on all identified HCPs.However,in order to be routinely implemented in biopharmaceutical companies,liquid chromatography-MS based methods still need to be standardized to provide highest sensitivity and robust and accurate quantification.Here,we present a promising MS-based analytical workflow coupling the use of an innovative quantification standard,the HCP Profiler solution,with a spectral library-based data-independent acquisition(DIA)method and strict data validation criteria.The performances of the HCP Profiler solution were compared to more conventional standard protein spikes and the DIA approach was benchmarked against a classical datadependent acquisition on a series of samples produced at various stages of the manufacturing process.While we also explored spectral library-free DIA interpretation,the spectral library-based approach still showed highest accuracy and reproducibility(coefficients of variation<10%)with a sensitivity down to the sub-ng/mg mAb level.Thus,this workflow is today mature to be used as a robust and straightforward method to support mAb manufacturing process developments and drug products quality control.展开更多
A stability-indicating UPLC method has been developed and validated for the determination of related substances of Posaconazole with its four related substances (Hydroxytriazole, Tosylated compound, Deshydroxy posacon...A stability-indicating UPLC method has been developed and validated for the determination of related substances of Posaconazole with its four related substances (Hydroxytriazole, Tosylated compound, Deshydroxy posaconazole and Benzylated posaconazole) in the drug substance. Forthwith simple UPLC chromatographic separations were achieved on a Waters Acquity BEH shield C18 (100 mm length, 2.1 mm internal diameter and 1.7 μm particle size) with a mobile phase containing 0.1% Orthophosphoric acid (i.e. 1 mL in 1000 mL water) in gradient combination with acetonitrile (ACN) at a flow rate of 0.5 mL/min and the eluent were monitored at 210 nm. As a result, the resolution of Posaconazole from any of impurities was found to be greater than 2.0. The test solution and spiked solutions were found to be stable in the diluent for 48 h. For the purpose method to be stability indicating, forced degradation studies were conducted and the method resolved the drug from its known impurities, stated above, and from additional impurities generated when POS subjected to forced degradation;the mass balance was found close to 100%. Regression analyses indicate correlation coefficient value greater than 0.999 for Posaconazole and its known impurities. The LOD for Posaconazole and the known impurities was at a level below 0.05%. The method has shown good, consistent recoveries for known impurities (89% - 106%). To summarise, the method was found to be accurate, precise, linear, specific, sensitive, rugged, robust, and stability-indicating.展开更多
Arformoterol (R, R) is an enantiomer of racemic formoterol, was the first long-acting beta agonist (LABA), approved by U.S. food and Drug Administration (FDA). The Arformoterol which is used for the treatment of Chron...Arformoterol (R, R) is an enantiomer of racemic formoterol, was the first long-acting beta agonist (LABA), approved by U.S. food and Drug Administration (FDA). The Arformoterol which is used for the treatment of Chronic obstructive pulmonary disease (COPD) are inhaled bronchodilator drugs which are delivered directly to the patient’s airways through a different mechanism. The formulated drug product is kept for stability study as per ICH guideline [1] and during its stability interval analysis by HPLC (High performance liquid chromatography), an unknown peak observed at level around 0.1% which is well below the identification threshold of 0.5% but after heating it crossed the identification threshold. The approach to identify anonymous species of Arformoterol aqueous formulation was adopted as first to generate the impurity in sample, isolate, enrich and Characterize through LC-MS/MS and NMR Spectroscopy. Based on the spectral data the anonymous species was identified as an “Imine impurity”, it is secondary degradant of Amine impurity of Arformoterol formed due to reaction with leachable observed in LDPE respules.展开更多
A total of 2 088 marine microorganisms including 1 392 strains of bacteria and 696 strains of fungi were isolated from diverse marine environment such as the South Pole, the North Pole, and Qingdao tideland, etc. Thro...A total of 2 088 marine microorganisms including 1 392 strains of bacteria and 696 strains of fungi were isolated from diverse marine environment such as the South Pole, the North Pole, and Qingdao tideland, etc. Through a systematic screening process involving the use of Pyricularia oryzae mode, 90 bacteria and 31 fungi strains demonstrating positive bioactivities were identified. The rates of active strains of marine bacteria and marine fungi were 6.5% and 4.5%, respectively. The relationships between the active strains and the sampling locations and hosts were studied. For marine bacteria, the three locations showing the highest rotes of active strains were 8.4% in the Zhujiang Estuary, 7.2% at the North Pole and 6.3% in the Bohai Sea. For marine fungi, the highest rates observed were 7.8% at the South Pole, 7.4% in the South China Sea and 6.8% at the Qingdao tideland. An analysis of the host showed that the three highest rates of active strain for marine bacteria were 8.2% for seawater from the Zhujiang Estuary, 8% for alga from the Qingdao tideland and 7.6% for sea mud from the North Pole. For marine fungi, the highest rates observed were 8.3% for Qingdao actiniae, 7.4% for South China Sea poriferan and 4.5% for soil of Qingdao Suaeda salsa. Four fungi and two bacteria samples were selected for further study because of their high bioactivity. They were found to be active towards several pathogenic microorganisms, and demonstrated stable genetic and thermal characteristics and conservation activities.展开更多
Per-and polyfluoroalkyl substances(PFASs)are emerging persistent organic pollutants(POPs).In this study,47 surface sediment samples were collected from the Yellow River Delta wetland(YRDW)to investigate the occurrence...Per-and polyfluoroalkyl substances(PFASs)are emerging persistent organic pollutants(POPs).In this study,47 surface sediment samples were collected from the Yellow River Delta wetland(YRDW)to investigate the occurrence,spatial distribution,potential sources,and ecological risks of PFASs.Twenty-three out of 26 targeted PFASs were detected in surface sediment samples from the YRDW,with totalΣ23PFASs concentrations ranging from 0.23 to 16.30 ng g^(-1) dw and a median value of 2.27 ng g^(-1) dw.Perfluorooctanoic acid(PFOA),perfluorobutanoic acid(PFBA)and perfluorooctanesulfonic acid(PFOS)were the main contaminants.The detection frequency and concentration of perfluoroalkyl carboxylic acids(PFCAs)were higher than those of perfluoroal-kanesulfonic acids(PFSAs),while those of long-chain PFASs were higher than those of short-chain PFASs.The emerging PFASs substitutes were dominated by 6:2 chlorinated polyfluoroalkyl ether sulfonic acid(6:2 Cl-PFESA).The distribution of PFASs is significantly influenced by the total organic carbon content in the sediments.The concentration of PFASs seems to be related to human activities,with high concentration levels of PFASs near locations such as beaches and villages.By using a positive matrix factorization model,the potential sources of PFASs in the region were identified as metal plating mist inhibitor and fluoropolymer manufacturing sources,metal plating industry and firefighting foam and textile treatment sources,and food packaging material sources.The risk assessment indicated that PFASs in YRDW sediments do not pose a significant ecological risk to benthic organisms in the region overall,but PFOA and PFOS exert a low to moderate risk at individual stations.展开更多
A linear 7-step synthesis of vildagliptin-β-O-glucuronide (2) starting from commercially available D-glucurono-6, 3-lactone (3) was herein achieved with 11.3% overall yield. Efficient preparation of compound 6 in pu...A linear 7-step synthesis of vildagliptin-β-O-glucuronide (2) starting from commercially available D-glucurono-6, 3-lactone (3) was herein achieved with 11.3% overall yield. Efficient preparation of compound 6 in pure α form was obtained, which was proved critical to achieve high anomeric selectivity in β-O-glycosylation later. The direct β-O-glycosylation of vildagliptin (1) containing both a tertiary alcohol and a secondary amine was studied and achieved in good yield. The deprotection step to afford product was delicately executed to avoid hydrolysis of nitrile group. The target compound 2 was obtained after purification by reversed-phase C18 chromatography.展开更多
Lipophilic marine algal toxins(LMATs)are produced by some toxigenic microalgae,which pose a serious threat to marine ecosystem and even human health.The occurrence and environmental control factors of LMATs in the sur...Lipophilic marine algal toxins(LMATs)are produced by some toxigenic microalgae,which pose a serious threat to marine ecosystem and even human health.The occurrence and environmental control factors of LMATs in the surface seawater and phytoplankton in spring in Laizhou Bay in which Huanghe(Yellow)River estuary is included,in Shandong,East China were investigated.Okadaic acid(OA),pectenotoxin-2(PTX2),dinophysistoxin-1(DTX1),pectenotoxin-2 seco acid(PTX2 SA),DTX2,7-epi-PTX2 SA,PTX11,and 13-desmethyl spirolide C(SPX1)were detected from the surface seawater samples,and PTX2,7-epi-PTX2 SA,OA,DTX2,DTX1,PTX2 SA,and PTX11 were discovered in the phytoplankton samples showed a decreasing trend.The concentrations of∑LMATs in the seawater and phytoplankton ranged 2.03-74.38 ng/L on average of 13.72 ng/L and 0.98-479.27 pg/L on average of 50.20 pg/L,respectively.The joint influence of terrigenous input and internal circulation could promote the growth,toxin production,and toxin release of toxin-producing algae,leading to a higher content of LMATs in the bay nearby the Huanghe River estuary in both seawater and phytoplankton.The concentration of LMATs in spring was higher than that in summer,showing obvious seasonal variation.In addition,no significant correlation between most of the physiochemical parameters and LMAT contents in seawater was revealed by correlation analysis except for the positive correlation between DTX2 and chlorophyll a,OA and NH4-N.However,the increase of dissolved inorganic nitrogen content in seawater could enhance the production of OA,DTX1,and DTX2 in phytoplankton due probably to that the inorganic N input could benefit the growth and stimulate toxin production of toxin-producing algae.The result also proved that some PTX2 may be originated from Procentrum spp.and OA,DTXs and part of PTX2 may be originated from Dinophysis spp.展开更多
Water radical cations,the crucial intermediates in many aqueous reactions and biochemical processes,are difficult to investigate experimentally due to their short lifetime andlowabundance.Herein,ahomemade device based...Water radical cations,the crucial intermediates in many aqueous reactions and biochemical processes,are difficult to investigate experimentally due to their short lifetime andlowabundance.Herein,ahomemade device based on energy-tunable discharge was employed to deposit suitable amounts of energy to atmospheric pressure pure water vapor for abundant production of water radical cations,stabilized as(H_(2)O)n^(+·)(n=2-5)with a maximal abundance of≥8.3×10^(6) cps for(H_(2)O)_(2)^(+·),characterized by mass spectrometry(MS).The abundance of water radical cations was optimized by adjusting the experimental parameters such as the discharge voltage(2.5 kV),temperature of the MS inlet(140℃),carrier gas flow(20mL/min),and the distance between the discharge tip and MS inlet(12 mm).The ambient formation of water radical cationswas further confirmedby thehigh reactivity of as-prepared water radical cations,which reacted with benzene,ethyl acetate,and dimethyl disulfide instantly,showing rich chemistry with ionic and radical characteristics.Moreover,the computations usingCCSD(T)//MP2 method and density functional theory confirmed that the O-O single-electron bound dimer(B),as well as the hydronium hydroxyl radical complex(A),accounted for the unusual chemistry of the water radical cations,providing a facile approach to access the high reactivity ofwater radical cations under the ambient conditions.展开更多
文摘The development and delivery of high quality therapeutic products necessitates the need for highthrough-put (HTP) process development tools. Traditionally, these works requires a combination of shake flask and small-scale stirred tank bioreactor (STR) which are labor and resource intensive and time-consuming. Here we demonstrate a strategy for rapid and robust cell culture process development by evaluating and implementing the use of a new HTP disposable micro bioreactor (MBR) called AMBRTM system (Advanced Microscale Bioreactor) that has the capabilities for automated sampling, feed addition, pH, dissolved oxygen (DO), gassing and agitation controls. In these studies the performance of two monoclonal antibody (MAb) producing cell lines (MAb1 and MAb2) was evaluated both in the AMBR system and 3-L STR. We demonstrated that cell culture performance (growth and viability, production titer and product quality) were similar in both vessel systems. Furthermore, process control and feed optimization were demonstrated in an additional cell line (MAb3) in the disposable MBR and its performance confirmed at STR scale. The results indicate that the AMBR system can be used to streamline the process development effort and facilitate a rapid and robust cell culture process development effort for MAb programs in a HTP manner.
文摘The present method gives a detailed description for the development and validation of a simple stability indicating reverse phase liquid chromatographic method for 10-hydroxycamptothecin(10-HCTN) in the presence of its impurities namely Imp A and Imp B along with degradation products generated from forced degradation studies. The drug was subjected to stress conditions of hydrolysis (acid, base and neutral), oxidative, photolytic and thermal stress degradation. Degradation was observed when subjected to treatment with peroxides or under conditions normally used for typical acid and base hydrolysis. The drug was found to be stable under other stress conditions attempted such as photolytic and thermal. Successful separation and isolation of the drug from related impurities and degradation products formed under stress conditions was achieved on an Inertsil ODS-3V (250 mm × 4.6 mm, 5 μm) column using a phosphate buffer, acetonitrile, methanol and Nanopure water. The developed HPLC method was validated with respect to specificity, linearity, accuracy, precision, sensitivity, robustness and solution stability. The assay method was found to be linear in the range of 0.16 mg/mL to 0.24 mg/mL with a correlation coefficient of 0.999 and the linearity of the impurities was established from 0.02% (LOQ) to 0.3%. Recoveries of assay and impurities were found between 99.4% and 100.3%. The developed HPLC method can be used to determine the related substances and assay determinations of 10-HCTN and also to evaluate the quality and long term stability of production samples.
文摘The present method provides the detailed description of development and validation of a simple stability indicating re- verse phase column liquid chromatographic method for Olmesartan in the presence of its impurities namely Imp-A, Imp-B, Imp-C, Imp-D, Imp-E, Imp-F and Imp-G and degradation products generated from forced degradation studies. The drug substance was subjected to stress conditions of aqueous hydrolysis, Oxidative, photolytic and thermal stress degradation. The degradation of Olmesartan was observed under acid hydrolysis, base hydrolysis and peroxide. The drug was found to be stable to other stress conditions attempted. Successful separation of the drug from synthetic impu- rities and degradation products formed under stress conditions was achieved on symmetry C18, 150 mm × 4.6 mm, 5μ column using a phosphate buffer, Acetonitrile and Milli Q water. The developed LC method was validated with respect to specificity, linearity, accuracy, precision, raggedness and robustness. The assay method was found to be linear in the range of 250 μg?mL–1 to with 1000 μg?mL–1 correlation coefficient of 0.9999 and the linearity of the impurities was es- tablished from LOQ to 0.4%. Recoveries of assay and impurities were found between 98.5% and 101.2%. The devel- oped LC method to determine the related substances and assay determinations of Olmesartan can be used to evaluate the quality of regular production samples and stability samples. To best of our knowledge, the validated stability indi- cating LC method which separates all the impurities disclosed in this investigation was not published elsewhere.
基金the Laoshan Laboratory(No.LSKJ202203901)the Natural Science Foundation of Shandong Province,China(No.ZR2021MD079)+1 种基金the APEC Cooperation Fund(No.WJ1323001)the Asian Cooperation Fund(Nos.WJ1223001,WJ0923015)。
文摘To explore the relationship of microplastic pollution in different media in marine environment,microplastics in the surface seawater and sediments of Laizhou Bay,Bohai Sea,North China,were studied.Seawater samples were collected using a pre-concentrator equipped with a 20-μm mesh size sieve,and sediment samples were collected by a box sampler.The shape,color,size,and type of microplastics were obtained by a stereomicroscope and a Fourier transform infrared spectrometer(ATR-μ-FT-IR).Results show that the abundance of microplastics in the surface seawater of Laizhou Bay was 858.3±573.2 items/m~3,and that of microplastics in sediments was 151.0±77.4 items/kg dry weight(d.w.)The microplastics in seawater and sediments were mainly fibrous.Meanwhile,the microplastics in seawater were mainly transparent,and those in sediments were transparent and blue.The highest proportion of microplastics in seawater was rayon(77.48%),followed by polyethylene terephthalate(PET,13.17%).The highest proportion of microplastics in sediments was rayon(73.66%),followed by PET(8.90%).The size of microplastics in 1000-2000μm accounted for the largest proportion of 28.54%in seawater,while that in 500-1000μm took 27.93%in sediment.Microplastics in seawater and sediment showed medium-level pollution.In seawater,microplastic abundance was higher in offshore and nearshore areas of Weifang.In sediment,microplastic abundance was higher in offshore and nearshore areas of Dongying.The results of the principal component analysis(PCA)indicated that microplastics in sediment exhibited greater stability compared to those in seawater.The microplastics in seawater and sediment show a positive correlation in terms of shape and plastic type,while exhibiting a negative correlation in terms of color.Overall,microplastics in sediments were smaller in size,and those in seawater and sediments had consistent size distribution characteristics in space.
基金supported by the National Natural Science Foundation of China(Nos.42107284 and 22078177)the Postdoctoral Fellowship Program of CPSF(No.GZB20240410)。
文摘Decabromodiphenyl ethane(DBDPE)is widely used as an additive flame retardant and has led to global pollution.Its has a large molecular mass and is prone to debromination and degradation under photothermal conditions,resulting in smaller homologous compounds.Due to the lack of standard substances for debromination products,the in-depth study of DBDPE environmental geochemical behavior through debromination conversion has been hindered.Therefore,based on DBDPE photodegradation experiment,this study first analyzed and identified the brominated products of DBDPE using high-performance liquid chromatography-atmospheric pressure photoionization-time of flight mass spectrometry(HPLC-APPI-TOF/MS).Four debromination products-nonabromodiphenyl ethane(nonaBDPE),octabromodiphenyl ethane(octa-BDPE),heptabromodiphenyl ethane(hepta-BDPE)and hexabromodiphenyl ethane(hexa-BDPE)are identified based on the characteristic ion peak of[M-Br+O]^(-) in negative ion mode.Subsequently,using methanol as the mobile phase,four debromination products of DBDPE were separated and purified with a semi-preparative high-performance liquid chromatography(SP-HPLC)system equipped with an Agilent Zorbax Eclipse PAH column(4.6 mm×250 mm,5μm).The first-time acquisition of hexa-BDPE(60.00μg),octa-BDPE(19.40μg),hepta-BDPE(31.20μg)and octa-BDPE(isomer,45.20μg)with purity exceeding 90%has been achieved.Among them,the purity of one hepta-BDPE monomer is as high as 98.91%.This study indicates that based on photodegradation experiments,the combination of HPLC-APPI-TOF/MS and SP-HPLC techniques can rapidly identify and prepare DBDPE debrominated products.This approach meets the requirements for preliminary research on the pollution characteristics of DBDPE debrominated compounds and offers a feasible solution for the preparation of standard reference materials for emerging pollutants.
基金supported by the National High-tech Research Project ("863" Project) of China under contract Nos 2003AA635180 and 2006AA09Z167the Public Welfare Project of Marine Science Research under contract No 200705011the open project of Key Laboratory of Integrated Marine Monitoring and Applied Technologies for Harmful Algal Blooms,SOA, China under contract No200811
文摘Hierarchical clustering analysis and principal component analysis （PCA） methods were used to assess the similarities and dissimilarities of the entire Excitation-emission matrix spectroscopy （EEMs） data sets of samples collected from Jiaozhou Bay, China. The results demonstrate that multivariate analysis facilitates the complex data treatment and spectral sorting processes, and also enhances the probability to reveal otherwise hidden information concerning the chemical characteristics of the dissolved organic matter （DOM）. The distribution of different water samples as revealed by multivariate results has been used to track the movement of DOM material in the study area, and the interpretation is supported by the results obtained from the numerical simulation model of substance tracing technique, which show that the substance discharged by Haibo River can be distributed in Jiaozhou Bay.
文摘Budesonide is a corticosteroid used for the treatment of asthma via various matrices and inhalation mechanisms. An unknown peak of Budesonide aqueous formulation has been investigated during stability study wherein the impurity level observed around 0.1% well below the threshold 0.5%. The approach to identify anonymous species was adopted as first to generate the impurity in sample, isolate, enrich and was subjected to LC-MS/MS and NMR for spectral studies. Based on the spectral data the anonymous species were identified as a “Lumibudesonide’’ ((5aR,5bS,5cS,6S,7aS,7bS,10aR,11aS,11bS)-6-hydroxy-7b-(2-hydroxyacetyl)-5b,7a-dimethyl-9-propyl 1,5a,5b,5c,6,7,7a,7b,10a,11,11a,11b dodecahydrocyclopenta[2'',3'']cyclopropa [1'',2'':3', 4']benzo [1',2':4,5]indeno [1,2-d][1,3]dioxol-5(2H)-one), which is observed in photolysis of Budesonide.
文摘Severe acute respiratory syndrome-associated coronavirus 2 is a major global health issue and is driving the need for new therapeutics.The surface spike protein,which plays a central role in virus infection,is currently the target for vaccines and neutralizing treatments.The emergence of novel variants with multiple mutations in the spike protein may reduce the effectiveness of neutralizing antibodies by altering the binding activity of the protein with angiotensin-converting enzyme 2(ACE2).To understand the impact of spike protein mutations on the binding interactions required for virus infection and the effectiveness of neutralizing monoclonal antibody(mAb)therapies,the binding activities of the original spike protein receptor binding domain(RBD)sequence and the reported spike protein variants were investigated using surface plasmon resonance.In addition,the interactions of the ACE2 receptor,an antispike mAb(mAb1),a neutralizing mAb(mAb2),the original spike RBD sequence,and mutants D614G,N501Y,N439K,Y453F,and E484K were assessed.Compared to the original RBD,the Y453F and N501Y mutants displayed a significant increase in ACE2 binding affinity,whereas D614G had a substantial reduction in binding affinity.All mAb-RBD mutant proteins displayed a reduction in binding affinities relative to the original RBD,except for the E484K-mAb1 interaction.The potential neutralizing capability of mAb1 and mAb2 was investigated.Accordingly,mAb1 failed to inhibit the ACE2-RBD interaction while mAb2 inhibited the ACE2-RBD interactions for all RBD mutants,except mutant E484K,which only displayed partial blocking.
文摘A stability indicating LC method was developed for the simultaneous determination of Amlodipine and Benazepril capsules in pharmaceutical dosage form. Efficient chromatographic separation was achieved on Symmetry C18 stationary phase with simple combination of amobile phase containing 750 mL of DI Water, 250 mL of Acetonitrile and 2 mL of Octylamine into suitable container with adjusted pH to 2.50 ± 0.05 with the aid of Ortho phosphoric acid delivered in an isocratic mode and quantification was carried out using UV detection at 240 nm at a flow rate of 1.0 mL·min-1 with an injection volume of 20 μl and ambient column temperature. This method is capable to detect both the drug components of Amlodipine and Benazepril in presence of their degradation products (Amlodipine Imp-A and Benazepril Impurity-C) with a detection level of 0.05%. Amlodipine/Benazepril in their combination drug product were exposed to thermal, photolytic, hydrolytic and oxidative stress conditions, and the samples were analysed. Peak homogeneity data of Amlodipine and Benazeprilis were obtained using PDA detector, in the stressed sample chromatograms, demonstrating the specificity. The method shows excellent linearity over a range of 0.05%-2.0% for Amlodipine, Amlodipine Impurity-A and 0.05%-5.0% for Benazepril and Benazepril Impurity-C. The correlation coefficient for Amlodipine and Benazepril is 1. The relative standard deviation was always less than 2%. The proposed method was found to be suitable and accurate for quantitative determination and the stability study of Amlodipine and Benazepril in pharmaceutical preparations. The developed HPLC method was validated with respect to linearity & range, accuracy, precision and robustness.
文摘BACKGROUND Mixed neuroendocrine non-neuroendocrine neoplasm(MiNEN)is a rare diagnosis,mainly encountered in the gastro-entero-pancreatic tract.There is limited knowledge of its epidemiology,prognosis and biology,and the best management for affected patients is still to be defined.AIM To investigate clinical-pathological characteristics,treatment modalities and survival outcomes of a retrospective cohort of patients with a diagnosis of MiNEN.METHODS Consecutive patients with a histologically proven diagnosis of MiNEN were identified at 5 European centres.Patient data were retrospectively collected from medical records.Pathological samples were reviewed to ascertain compliance with the 2017 World Health Organisation definition of MiNEN.Tumour responses to systemic treatment were assessed according to the Response Evaluation Criteria in Solid Tumours 1.1.Kaplan-Meier analysis was applied to estimate survival outcomes.Associations between clinical-pathological characteristics and survival outcomes were explored using Log-rank test for equality of survivors functions(univariate)and Cox-regression analysis(multivariable).RESULTS Sixty-nine consecutive patients identified;Median age at diagnosis:64 years.Males:63.8%.Localised disease(curable):53.6%.Commonest sites of origin:colon-rectum(43.5%)and oesophagus/oesophagogastric junction(15.9%).The neuroendocrine component was;predominant in 58.6%,poorly differentiated in 86.3%,and large cell in 81.25%,of cases analysed.Most distant metastases analysed(73.4%)were occupied only by a poorly differentiated neuroendocrine component.Ninety-four percent of patients with localised disease underwent curative surgery;53%also received perioperative treatment,most often in line with protocols for adenocarcinomas from the same sites of origin.Chemotherapy was offered to most patients(68.1%)with advanced disease,and followed protocols for pure neuroendocrine carcinomas or adenocarcinomas in equal proportion.In localised cases,median recurrence free survival(RFS);14.0 months(95%CI:9.2-24.4),and median overall survival(OS):28.6 months(95%CI:18.3-41.1).On univariate analysis,receipt of perioperative treatment(vs surgery alone)did not improve RFS(P=0.375),or OS(P=0.240).In advanced cases,median progression free survival(PFS);5.6 months(95%CI:4.4-7.4),and median OS;9.0 months(95%CI:5.2-13.4).On univariate analysis,receipt of palliative active treatment(vs best supportive care)prolonged PFS and OS(both,P<0.001).CONCLUSION MiNEN is most commonly driven by a poorly differentiated neuroendocrine component,and has poor prognosis.Advances in its biological understanding are needed to identify effective treatments and improve patient outcomes.
基金supported by the“Association Nationale de la Recherche et de la Technologie”and UCB Pharma S.A.(Belgium and France)via the CIFRE fellowship of Steve Hessmannsupported by the“Agence Nationale de la Recherche”via the French Proteomic Infrastructure ProFI FR2048(ANR-10-INBS-08-03).
文摘Monitoring of host cell proteins(HCPs)during the manufacturing of monoclonal antibodies(mAb)has become a critical requirement to provide effective and safe drug products.Enzyme-linked immunosorbent assays are still the gold standard methods for the quantification of protein impurities.However,this technique has several limitations and does,among others,not enable the precise identification of proteins.In this context,mass spectrometry(MS)became an alternative and orthogonal method that delivers qualitative and quantitative information on all identified HCPs.However,in order to be routinely implemented in biopharmaceutical companies,liquid chromatography-MS based methods still need to be standardized to provide highest sensitivity and robust and accurate quantification.Here,we present a promising MS-based analytical workflow coupling the use of an innovative quantification standard,the HCP Profiler solution,with a spectral library-based data-independent acquisition(DIA)method and strict data validation criteria.The performances of the HCP Profiler solution were compared to more conventional standard protein spikes and the DIA approach was benchmarked against a classical datadependent acquisition on a series of samples produced at various stages of the manufacturing process.While we also explored spectral library-free DIA interpretation,the spectral library-based approach still showed highest accuracy and reproducibility(coefficients of variation<10%)with a sensitivity down to the sub-ng/mg mAb level.Thus,this workflow is today mature to be used as a robust and straightforward method to support mAb manufacturing process developments and drug products quality control.
文摘A stability-indicating UPLC method has been developed and validated for the determination of related substances of Posaconazole with its four related substances (Hydroxytriazole, Tosylated compound, Deshydroxy posaconazole and Benzylated posaconazole) in the drug substance. Forthwith simple UPLC chromatographic separations were achieved on a Waters Acquity BEH shield C18 (100 mm length, 2.1 mm internal diameter and 1.7 μm particle size) with a mobile phase containing 0.1% Orthophosphoric acid (i.e. 1 mL in 1000 mL water) in gradient combination with acetonitrile (ACN) at a flow rate of 0.5 mL/min and the eluent were monitored at 210 nm. As a result, the resolution of Posaconazole from any of impurities was found to be greater than 2.0. The test solution and spiked solutions were found to be stable in the diluent for 48 h. For the purpose method to be stability indicating, forced degradation studies were conducted and the method resolved the drug from its known impurities, stated above, and from additional impurities generated when POS subjected to forced degradation;the mass balance was found close to 100%. Regression analyses indicate correlation coefficient value greater than 0.999 for Posaconazole and its known impurities. The LOD for Posaconazole and the known impurities was at a level below 0.05%. The method has shown good, consistent recoveries for known impurities (89% - 106%). To summarise, the method was found to be accurate, precise, linear, specific, sensitive, rugged, robust, and stability-indicating.
文摘Arformoterol (R, R) is an enantiomer of racemic formoterol, was the first long-acting beta agonist (LABA), approved by U.S. food and Drug Administration (FDA). The Arformoterol which is used for the treatment of Chronic obstructive pulmonary disease (COPD) are inhaled bronchodilator drugs which are delivered directly to the patient’s airways through a different mechanism. The formulated drug product is kept for stability study as per ICH guideline [1] and during its stability interval analysis by HPLC (High performance liquid chromatography), an unknown peak observed at level around 0.1% which is well below the identification threshold of 0.5% but after heating it crossed the identification threshold. The approach to identify anonymous species of Arformoterol aqueous formulation was adopted as first to generate the impurity in sample, isolate, enrich and Characterize through LC-MS/MS and NMR Spectroscopy. Based on the spectral data the anonymous species was identified as an “Imine impurity”, it is secondary degradant of Amine impurity of Arformoterol formed due to reaction with leachable observed in LDPE respules.
文摘A total of 2 088 marine microorganisms including 1 392 strains of bacteria and 696 strains of fungi were isolated from diverse marine environment such as the South Pole, the North Pole, and Qingdao tideland, etc. Through a systematic screening process involving the use of Pyricularia oryzae mode, 90 bacteria and 31 fungi strains demonstrating positive bioactivities were identified. The rates of active strains of marine bacteria and marine fungi were 6.5% and 4.5%, respectively. The relationships between the active strains and the sampling locations and hosts were studied. For marine bacteria, the three locations showing the highest rotes of active strains were 8.4% in the Zhujiang Estuary, 7.2% at the North Pole and 6.3% in the Bohai Sea. For marine fungi, the highest rates observed were 7.8% at the South Pole, 7.4% in the South China Sea and 6.8% at the Qingdao tideland. An analysis of the host showed that the three highest rates of active strain for marine bacteria were 8.2% for seawater from the Zhujiang Estuary, 8% for alga from the Qingdao tideland and 7.6% for sea mud from the North Pole. For marine fungi, the highest rates observed were 8.3% for Qingdao actiniae, 7.4% for South China Sea poriferan and 4.5% for soil of Qingdao Suaeda salsa. Four fungi and two bacteria samples were selected for further study because of their high bioactivity. They were found to be active towards several pathogenic microorganisms, and demonstrated stable genetic and thermal characteristics and conservation activities.
基金financially supported by the National Natural Science Foundation of China(NSFC)(No.42377217)the Cooperation Fund between Dongying City and Universities(No.SXHZ-2023-02-6).
文摘Per-and polyfluoroalkyl substances(PFASs)are emerging persistent organic pollutants(POPs).In this study,47 surface sediment samples were collected from the Yellow River Delta wetland(YRDW)to investigate the occurrence,spatial distribution,potential sources,and ecological risks of PFASs.Twenty-three out of 26 targeted PFASs were detected in surface sediment samples from the YRDW,with totalΣ23PFASs concentrations ranging from 0.23 to 16.30 ng g^(-1) dw and a median value of 2.27 ng g^(-1) dw.Perfluorooctanoic acid(PFOA),perfluorobutanoic acid(PFBA)and perfluorooctanesulfonic acid(PFOS)were the main contaminants.The detection frequency and concentration of perfluoroalkyl carboxylic acids(PFCAs)were higher than those of perfluoroal-kanesulfonic acids(PFSAs),while those of long-chain PFASs were higher than those of short-chain PFASs.The emerging PFASs substitutes were dominated by 6:2 chlorinated polyfluoroalkyl ether sulfonic acid(6:2 Cl-PFESA).The distribution of PFASs is significantly influenced by the total organic carbon content in the sediments.The concentration of PFASs seems to be related to human activities,with high concentration levels of PFASs near locations such as beaches and villages.By using a positive matrix factorization model,the potential sources of PFASs in the region were identified as metal plating mist inhibitor and fluoropolymer manufacturing sources,metal plating industry and firefighting foam and textile treatment sources,and food packaging material sources.The risk assessment indicated that PFASs in YRDW sediments do not pose a significant ecological risk to benthic organisms in the region overall,but PFOA and PFOS exert a low to moderate risk at individual stations.
文摘A linear 7-step synthesis of vildagliptin-β-O-glucuronide (2) starting from commercially available D-glucurono-6, 3-lactone (3) was herein achieved with 11.3% overall yield. Efficient preparation of compound 6 in pure α form was obtained, which was proved critical to achieve high anomeric selectivity in β-O-glycosylation later. The direct β-O-glycosylation of vildagliptin (1) containing both a tertiary alcohol and a secondary amine was studied and achieved in good yield. The deprotection step to afford product was delicately executed to avoid hydrolysis of nitrile group. The target compound 2 was obtained after purification by reversed-phase C18 chromatography.
基金Supported by the Science&Technology Basic Resources Investigation Program of China(No.2018FY100200)the National Natural Science Foundation of China(Nos.U2106205,U1706217)+1 种基金the Global Change and Air-Sea Interaction II(No.GASI-01-ATP-STwin)the National Key Research and Development Project of China(No.2018YFC1407600)。
文摘Lipophilic marine algal toxins(LMATs)are produced by some toxigenic microalgae,which pose a serious threat to marine ecosystem and even human health.The occurrence and environmental control factors of LMATs in the surface seawater and phytoplankton in spring in Laizhou Bay in which Huanghe(Yellow)River estuary is included,in Shandong,East China were investigated.Okadaic acid(OA),pectenotoxin-2(PTX2),dinophysistoxin-1(DTX1),pectenotoxin-2 seco acid(PTX2 SA),DTX2,7-epi-PTX2 SA,PTX11,and 13-desmethyl spirolide C(SPX1)were detected from the surface seawater samples,and PTX2,7-epi-PTX2 SA,OA,DTX2,DTX1,PTX2 SA,and PTX11 were discovered in the phytoplankton samples showed a decreasing trend.The concentrations of∑LMATs in the seawater and phytoplankton ranged 2.03-74.38 ng/L on average of 13.72 ng/L and 0.98-479.27 pg/L on average of 50.20 pg/L,respectively.The joint influence of terrigenous input and internal circulation could promote the growth,toxin production,and toxin release of toxin-producing algae,leading to a higher content of LMATs in the bay nearby the Huanghe River estuary in both seawater and phytoplankton.The concentration of LMATs in spring was higher than that in summer,showing obvious seasonal variation.In addition,no significant correlation between most of the physiochemical parameters and LMAT contents in seawater was revealed by correlation analysis except for the positive correlation between DTX2 and chlorophyll a,OA and NH4-N.However,the increase of dissolved inorganic nitrogen content in seawater could enhance the production of OA,DTX1,and DTX2 in phytoplankton due probably to that the inorganic N input could benefit the growth and stimulate toxin production of toxin-producing algae.The result also proved that some PTX2 may be originated from Procentrum spp.and OA,DTXs and part of PTX2 may be originated from Dinophysis spp.
基金supported by a grant from the National Natural Science Foundation of China(grant no.215201-02007)the US National Science Foundation(grant no.1905087).
文摘Water radical cations,the crucial intermediates in many aqueous reactions and biochemical processes,are difficult to investigate experimentally due to their short lifetime andlowabundance.Herein,ahomemade device based on energy-tunable discharge was employed to deposit suitable amounts of energy to atmospheric pressure pure water vapor for abundant production of water radical cations,stabilized as(H_(2)O)n^(+·)(n=2-5)with a maximal abundance of≥8.3×10^(6) cps for(H_(2)O)_(2)^(+·),characterized by mass spectrometry(MS).The abundance of water radical cations was optimized by adjusting the experimental parameters such as the discharge voltage(2.5 kV),temperature of the MS inlet(140℃),carrier gas flow(20mL/min),and the distance between the discharge tip and MS inlet(12 mm).The ambient formation of water radical cationswas further confirmedby thehigh reactivity of as-prepared water radical cations,which reacted with benzene,ethyl acetate,and dimethyl disulfide instantly,showing rich chemistry with ionic and radical characteristics.Moreover,the computations usingCCSD(T)//MP2 method and density functional theory confirmed that the O-O single-electron bound dimer(B),as well as the hydronium hydroxyl radical complex(A),accounted for the unusual chemistry of the water radical cations,providing a facile approach to access the high reactivity ofwater radical cations under the ambient conditions.
