Synthesis strategies of covalent organic frameworks: An overview from nonconventional heating methods and reaction media

Covalent organic frameworks(COFs), as an emerging class of porous crystalline materials constructed by covalent links between the building monomers, have gained tremendous attention. Over the past 15 years, COFs have made rapid progress and substantial development in the chemistry and materials fields. However, the synthesis of COFs has been dominated by solvothermal methods for a long time and it usually involves high temperature, high pressure and toxic organic solvents, which created many challenges for environmental considerations. Recently,the exploration of new approaches for facile fabrication of COFs has aroused extensive interest. Hence, in this review, we comprehensively describe the synthetic strategies of COFs from the aspects of nonconventional heating methods and reaction media. In addition, the advantages,limitations and properties of the preparation methods are compared. Finally, we outline the main challenges and development prospects of the synthesis of COFs in the future and propose some possible solutions.

Diterpenoid Alkaloids and One Lignan from the Roots of Aconitum pendulum Busch

Diterpenoid alkaloids have neroprotective activity.Herein,three napelline-type diterpenoid alkaloids 1-3,two aconitine-type diterpenoid alkaloids 4-5,and one isoquinline-type alkaloid 6,as well as one lignan glycoside 7,have been isolated from the roots of Aconitum pendulum Busch.Compounds 1 and 7 were new compounds,and their chemical structures were determined on the basis of nuclear magnetic resonance(NMR)spectra and mass spectrometry analysis.A ThT assay revealed that compound 2 showed significant disaggregation potency on the Aβ_(1−42)aggregates.

Wolfberry extracts inhibit Aβ1-42 aggregation and rescue memory loss of AD drosophila

This study is to investigate the potential of wolfberry water extracts for the treatment of Alzheimer’s disease(AD)and the relationship between their anti-AD property and the geographic locations in China.Total extracts of all wolfberry samples showed the potent to decrease self-induced Aβ1-42 aggregation and Cu2+-induced Aβ1-42 aggregation and the antioxidant capacity as well as the bioactivity for binding biometal.A transgenic drosophila model assay revealed that TE of S1 and S6(S1-TE and S6-TE)at 100μg/mL demonstrated the potent rescue effect on memory loss compared to the positive control memantine at 20μg/mL.Further study also revealed the polysaccharide extracts could contribute to their anti-AD property,and the anti-AD activity conspicuously depends on growing environment.Wolfberry samples S1 and S6 showed much more potent anti-AD property.Meanwhile this study demonstrated that the Chinese commonly consumed wolfberry in boiling water might have the beneficial function to prevent AD pathology.

Phytochemicals and biological activities of Ligularia species

Ligularia,an important genus of the Compositae family,has captured the interest of natural product chemists for years.Phytochemical investigations on the title genus have led to isolation of hundreds of secondary metabolites with various skeletons.Herein,we summarized the chemical constituents of this genus and their biological activities over the past few decades.

Effects of Different Wall-breaking Methods on Extraction of Solanesol from Stems and Leaves of Potato

In order to extract solanesol from potato stems and leaves more effectively and improve the extraction rate of solanesol, the same batch of potato stems and leaves harvested from Guyuan, Ningxia was selected as a research object, cell wall of potato stems and leaves was broken by enzymolysis with cellulase and high- speed shearing, and then reflux-extracted with 95% ethanol. Solanesol content was determined by HPLC, and extract yield was calculated. Extract yield and solanesol extraction rate was used as an index for comparison of difference between the 2 wall-breaking methods, so as to select the optimal wall-breaking method. The results showed that enzymolysis with cellulase exhibited extraction rate and extract yield of solanesol of 91.38% and 8.02%, respectively, which were better than those under high-speed shear emulsification technique. The enzymolysis wall-breaking method has the advantages of simple operation and strong feasibility.

Two New Eudesmane Sesquiterpenoids from the Flowers of Chrysanthemum indicum

The fowers of Chrysanthemum indicum,i.e.Ye-ju-hua recorded in the Chinese Pharmacopoeia,has been widely used in China as an important heat-clearing and detoxifying herb for the treatment of infammation,headache,and vertigo.A phytochemical investigation of this herb has led to the isolation of two new eudesmane sesquiterpenoids,7-epi-eudesm4(15),11(13)-diene-1β,3β-diol(1)and 7-epi-1β-hydroxy-β-eudesmol(2).The molecular structures of these new sesquiterpenoids were established based on the comprehensive spectroscopic analyses,including NMR,MS,and IR,and comparing with the literatures.

Deep eutectic solvent-driven self-assembly of metal mercaptide complexes with enzyme-mimicking activities for detection of uric acid through one-step cascade catalytic reaction

This work presents a generic strategy to create a series of metal mercaptides complexes via coordination selfassembly between transition metals(Mn,Cu,Co,Fe,and Ni)and cysteine(Cys)by forming the sulfur-metal bridges.This strategy involves dissolving metal chlorides and Cys into deep eutectic solvents(DES),followed by the precipitation of metal mercaptides complexes(such as Cys-Mn)by adding water as an antisolvent,where DES serves as the solvent,shape directing,and capping agent,thereby preventing the formation of other metal impurities.Interestingly,the prepared complexes possess both laccase and peroxidase-like properties,allowing the design of a technique for the detection of L-3,4-dihydroxyphenylalanine(L-DOPA)and uric acid,respectively.The prepared Cys-Mn can linearly oxidize L-DOPA with its concentrations from 0.1 to 130μM and the detection limit was calculated to be 75.5 n M.Additionally,the Cys-Mn can mimic the activity of peroxidase towards oxidization of o-phenylenediamine at neutral p H,allowing single-step and one-pot cascade reactions for visual and fluorometric measurements of uric acid(UA)that could work in the range of 0.2-500μM UA with a detection limit of 0.06μM and 0.054μМ,respectively.The assay was successful in detecting UA in serum and urine samples with relative standard deviation(RSD)ranging from 7.3%to 10.2%and 3.0%-8.5%respectively,suggesting that it may prove useful in medical diagnostic testing.

Effect of Occupational Manganese Exposure on Uric Acid Levels in Human Urine

Objective To investigate the effect of long-term and low-level occupational Mn exposure on the level of uric acid （UA） in human urine. Methods In this study, 65 volunteers were recruited, who were working on welding and foundry work in an plant in Gansu province, China. Additionally, 29 control samples were collected from individuals who did not have any history of excessive Mn exposure. An improved high performance liquid chromatography system equipped with a diode-array detector （HPLC-DAD） method was developed to determine the UA level in human urine. A Spectra AA 220 Atomic Absorption Spectrophotometer （AAS） was used to measure the Mn level in the urine. Results The analytical method was validated acceptable accuracy, precision, and recovery significantly lower than that of control samples for concentrations ranging from 3.82-45.84 pg/mL with Overall, the UA levels of Mn exposure samples were （P〈O.O5）. Conclusion The practical method developed here is suitable for both routine monitoring of UA level in human urine and metabolism research. Long-term and low-level occupational Mn exposure may lead to a lower UA level in urine, and UA might be an indicator of the early stage of manganism.

Synthesis and modification of spherical/hollow metal-organic frameworks for efficient extraction of sulfonamides in aqueous environments

In this study,two novel spherical/hollow metal-organic frameworks were successfully synthesized,and further modified by a mild non-covalent modification strategy with dopamine and 1,4-benzenedithiol(BDT)as polymeric monomers to obtain pB DT@PDA-Ni-MOF and p BDT@PDA-Ni/Co-MOF,respectively.The results showed that the above MOFs possessed extremely fast adsorption rates and ideal adsorption capacities for sulfonamides(SAs)and the modified MOFs exhibited enhanced adsorption capacities for SAs owing to a large number of additional functional groups.Then,benefit of their regular morphology and size,a facile syringe-assisted dispersive solid phase extraction(S-DSPE)method was developed for efficient detection of SAs,which will provide a powerful tool for monitoring trace level of SAs in aqueous environment.

Preparation and Evaluation of Silicon Quantum Dots-Bonded Silica Stationary Phase for Reversed-Phase Chromatography

In this paper,silicon quantum dots(SiQDs)with green fluorescence are synthesized by solvothermal reaction of 3-(2,3-epoxypropoxy)propyltrimethoxysilane(GPTMS)and ethylenediaminetetraacetic acid(EDTA),and then SiQDs are bonded to the surface of silica to obtain a new nano-on-micro stationary phase(SiO_(2)-SiQDs)for reversed-phase chromatography.The successful preparation of SiO_(2)-SiQDs stationary phase is demonstrated by a variety of characterizations,such as transmission electron microscopy,laser confocal microscopy,elemental analysis and Fourier infrared spectroscopy.In addition,the chromatographic performance of the prepared stationary phase is evaluated and it shows good separation performance for non-polar substances such as alkylbenzene,aniline and polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography.It is also verified that the stationary phase has good methyl selectivity and shape selectivity.More interestingly,the separation of prednisolone and hydrocortisone isomers can also be achieved at a low ratio of organic solvents,indicating that this new stationary phase has a good application prospect in isomer separation.

Basic deep eutectic solvents as reactant, template and solvents for ultra-fast preparation of transition metal oxide nanomaterials

Developing a new type of deep eutectic solvents(DESs)is indispensable for expanding their application in various fields.Here,we report a series of new highly basic DESs.FT-IR,quantitative 1 H NMR,MD simulation and physical properties show that these basic liquids are made up of hydroxide acceptor of alkali metal hydroxides in which the hydrogen bonding interactions coordinate the donor.These DESs can be played three roles as new solvents,template and reactant for facile and ultra-fast preparation of transition metal oxide nanomaterials such as NiCo2 O4,MnCo2 O4,NiMn2 O4,CoCu2 O4 and Co3 O4 under mild condition.This work shows one of the low energy-intensive methods for nanomaterial preparation.These initial findings of basic deep eutectic solvents provide a potential applicability around the systematic development of transition metal oxide nanosheets.

Porous graphene decorated silica as a new stationary phase for separation of sulfanilamide compounds in hydrophilic interaction chromatography

Porous graphene(PG) has potential applications in numerous fields because of the existence of nanopores in the plane. In this study, porous graphene decorated silica microspheres(Sil-PG) were successfully fabricated by assembling PG onto the silica particles surface in deep eutectic solvents(DESs).Experimental results demonstrate that this new stationary phase can facilitate the separation of six sulfonamides compounds in hydrophilic chromatographic conditions. The successful synthesis of the SilPG stationary phase provides a basis for the application of porous graphene-modified materials as the stationary phase for liquid chromatography, and offers the possibility to broaden the application of PG in the field of chromatography.

Orthogonal array optimization of ionic liquid based dispersive liquid-liquid microextraction for toxic anilines in foods

A simple and rapid method of ionic liquid based dispersive liquid-liquid microextraction(DLLME) combining with high performance liquid chromatography(HPLC) was developed for the analysis of four toxic anilines in flour steamed bread and maize steamed bread.Several possible influential factors such as the type of ionic liquid and disperser solvent,extraction time,sample pH,ionic strength and the volume of ionic liquid and disperser solvent were optimized using single factor experiments and orthogonal array design(OAD) with OA 25(5 4) matrix.Analysis of variance(ANOVA) and percent contribution(PC) were used to investigate the significance of the factors of OAD.Sample pH and ionic strength are statistically demonstrated two chief factors.Under the optimum condition,the method exhibits a good linearity(r 2 > 0.99) over the studied range(50-1000 ng g 1) for anilines.The extraction factors and recoveries for the anilines in two kinds of steamed breads ranged between 34.1%-73.3% and 44.3%-95.3%,respectively.The limit of detections(LODs) and limit of quantitations(LOQs) ranged between 10-15 ng g 1 and 30-45 ng g-1.

Glycoalkaloids and phenolic compounds in three commercial potato cultivars grown in Hebei,China

In order to investigate the food nutrition and safety of potato,the objective of the present study is to quantify glycoalkaloids(-chaconine and-solanine)and phenolic compounds in three potato cultivars,namely,Russet Burbank,Atlantic,and Shepody,grown in Hebei,China,and these two classes of biologically active compounds in commercial dehydrated potato flakes were also investigated.The total glycoalkaloid levels in whole potatoes ranged from 4.72 mg/kg for Shepody potatoes to 34.45 mg/kg for Russet Burbank potatoes.The ratio of-chaconine to-solanine in whole potatoes ranged from 0.41 for Russet Burbank potatoes to 3.61 for Atlantic potatoes.The removal rate of total glycoalkaloids in Russet Burbank potatoes during dehydrated potato flake processing is 90.0%.Chlorogenic acid is the dominant phenolic compound in Russet Burbank potatoes.By contrast,Atlantic and Shepody potatoes contain considerable caffeic acid.The loss rate of phenolic compounds in Russet Burbank during dehydrated potato flake processing is 50.47%.

Mechanism regulating the inhibition of lung cancer A549 cell proliferation and structural analysis of the polysaccharide Lycium barbarum

The water-soluble polysaccharide LBP-1 was isolated and characterized from Lycium barbarum L.LBP-1 was mainly composed of arabinose,galactose,glucose,xylose,mannose at a molar ratio of 37.53:28.08:14.72:7.83:4.50,respectively.Based on nuclear magnetic resonance(NMR)and methylation analysis,the backbone of LBP-1 was speculated in theα-L-Ara(1→[5-α-L-Ara(1→3)-β-D-Galp-(1→]n→4)-α-D-Galp-(1[→5-α-L-Ara(1]n[→6)-β-D-Galp-(1→4)-β-D-Galp-(1→]n,and the side chains of LBP-1 were in theα-L-Ara(1→3)-β-D-Galp-(1→6 position.These results showed that LBP-1 inhibited the growth of cancer A549 cells through cell cycle arrest and apoptosis,with an IC50 value of 42.5μg/mL.In addition,LBP-1 altered the expression of Cyclin D1,Cyclin D3,and CDK 2,thus blocking the cell cycle in G0/G1 phase,reducing cell migration,and regulating the PI3K/Akt/mTOR signaling pathway to induce apoptosis.

Preparation of Silica-Based Superfi cially Porous Silica and its Application in Enantiomer Separations: a Review

Chromatographic substrate material,as a carrier of chromatographic stationary phases,plays a vital role in defining its chromatographic characteristics,including column efficiency,stability,peak capacity and so on.In recent years,superficially porous silica(SPS)was widely valued for its excellent performance in improving the column efficiency due to its special structural properties,which was considered as a real substitute for fully porous SiO_(2)(FPS)and had been used to develop a new generation of highly efficient stationary phase.To help researchers better understand the SPS and further promote its application and development in the field of chromatography,the rapid separation mechanism,preparation method and its applications in the rapid separation and analysis of enantiomers were systematically introduced,and the development prospects of SPS were also prospected in this paper.

Study on pharmacokinetics and tissue distribution of the isocorydine derivative (AICD) in rats by HPLC-DAD method

A simple and effective high-performance liquid chromatography with diode-array detection method coupled with a liquid-liquid extraction pretreatment has been developed for determining the pharmacokinetics and tissue distribution of a novel structurally modified derivative(8-acetaminoisocorydine) of isocorydine.According to the in vivo experiments data calculations by DAS 2.0 software,a two-compartment metabolic model was suitable for describing the pharmacokinetic of 8-acetaminoisocorydine in rats.8-Acetamino-isocorydine was absorbed well after oral administration,and the absolute bioavailability was 76.5%.The half-life of 8-acetamino-isocorydine after intravenous and oral administration was 2.2 h and 2.0 h,respectively.In vivo,8-acetamino-isocorydine was highly distributed in the lungs,kidney and liver;however,relatively little entered the brain,suggesting that 8-acetaminoisocorydine could not easily pass through the blood brain barrier.Our work describes the first characterization of the pharmacokinetic parameters and tissue distribution of 8-acetamino-isocorydine.The acquired data will provide useful information for the in vivo pharmacology of 8-acetaminoisocorydine,and can be applied to new drug research.

Two-dimensional MOF Cu-BDC nanosheets/ILs@silica core-shell composites as mixed-mode stationary phase for high performance liquid chromatography

Here,silica microspheres were decorated with two-dimensional metal-organic frameworks(2 D MOFs)nanosheets and ionic liquids,and evaluated as the mixed-mode stationary phase for chromatographic separation.The ionic liquids were used to assist the synthesis of 2 D MOFs nanosheets,and also acted as adhesives among the nanosheets and silica.In contrast with the 2 D MOFs-based column without ionic liquids and commercial columns,the prepared column exhibited enhanced chromatographic separation performance for partially hydrophilic compounds such as alkaloids,sulfonamides and antibiotics,etc.In addition to excellent chromatographic repeatability and stability,it has also been verified that the composites could be easily and repeatedly prepared.The relative standard deviation of the retention time of the same type of analyte between the three batches of materials was ranging from 0.21%to 1.7%.In short,these results indicated that the synthesized composites were promising separation material for liquid chromatography,which made it possible to broaden the application of 2 D MOFs in the field of chromatography.

The Bioactive Secondary Metabolites from Talaromyces species

The focus of this review is placed on the chemical structures from the species of the genus Talaromyces reported with reference to their biological activities.221 secondary metabolites,including 43 alkaloids and peptides,88 esters,31 polyketides,19 quinones,15 steroid and terpenoids,and 25 other structure type compounds,have been included,and 66 references are cited.