This study investigated the use of raspberry extract(RBE) for mitigating ethyl carbamate(EC) accumulation in Chinese rice wine(Huangjiu), a traditional fermented beverage. It focused on the addition of RBE to the ferm...This study investigated the use of raspberry extract(RBE) for mitigating ethyl carbamate(EC) accumulation in Chinese rice wine(Huangjiu), a traditional fermented beverage. It focused on the addition of RBE to the fermentation mash and its effects on EC levels. The results showed a significant reduction in EC production that could be attributed to RBE's role in altering urea and citrulline catabolism and inhibiting arginine metabolism, thus preventing EC precursors from reacting with ethanol. Additionally, RBE enhanced the rice wine's flavor profile, as shown by volatile component and amino acid analysis. This study also explored RBE's impact on the metabolism of arginine by Saccharomyces cerevisiae in a simulated fermentation environment, and found increased arginine, reduced urea and citrulline levels, altered enzyme activities, and gene expression changes in the arginine metabolism and transport pathways. In conclusion, the results clearly demonstrated RBE's efficacy in reducing the EC content in Chinese rice wine, offering valuable insights for EC reduction strategies.展开更多
Nitrene transfer reactions are powerful tools in synthetic organic chemistry.In recent years,transitionmetal catalyzed nitrene transfer reactions with carbamates as the nitrene precursors have been widely pursued.Such...Nitrene transfer reactions are powerful tools in synthetic organic chemistry.In recent years,transitionmetal catalyzed nitrene transfer reactions with carbamates as the nitrene precursors have been widely pursued.Such species undergoes facile C-H amination,aziridination,and bifunctionalization of alkenes under the catalysis of different transition metals including Rh,Fe,Ru and others,enabling the efficient construction of various nitrogen-containing molecules.In this review,the recent developments in nitrene transfer reactions with carbamates via N-O bond cleavage were introduced based on different types of reaction,and the key mechanistic information and synthetic applications of the methodologies were discussed.展开更多
Aim To develop a novel selective protection strategy for the synthesis of ribostamycin cyclic carbamate derivatives. Methods Ribostamycin protected by carbobenzoxy group was treated with Nail, to give different protec...Aim To develop a novel selective protection strategy for the synthesis of ribostamycin cyclic carbamate derivatives. Methods Ribostamycin protected by carbobenzoxy group was treated with Nail, to give different protected intermediates under respective controllable cyclization reaction conditions. New ribostamycin derivative was obtained after the cleavage of carbobenzoxy groups. Result The novel selective protection of ribostamycin was achieved by the synthesis of protected intermediates. New ribostamycin derivative was obtained, but showed no expected antibacterial activity. Conclusion Several ribostamycin cyclic carbamate derivatives were obtained by novel selective protection strategy, which shows the practicability and convenience of the protection strategy. But these new ribostamycin derivatives containing cyclic carbamates structure may not be an ideal leading compound for antibiotic activity.展开更多
A novel method for the determination of five carbamate pesticides （metolcarb, carbofuran, carbaryl, isoprocard and diethofencard） in water samples was developed by dispersive liquid-liquid microextraction （DLLME） ...A novel method for the determination of five carbamate pesticides （metolcarb, carbofuran, carbaryl, isoprocard and diethofencard） in water samples was developed by dispersive liquid-liquid microextraction （DLLME） coupled with high performance liquid chromatography-diode array detector （HPLC-DAD）. Some experimental parameters that influence the extraction efficiency were studied and optimized to obtain the best extraction results. Under the optimum conditions for the method, the calibration curve was linear in the concentration range from 5 to 1000 ng mL^-1 for all the five carbamate pesticides, with the correlation coefficients （r^2） varying from 0.9984 to 0.9994. Good enrichment factors were achieved ranging from 80 to 177- fold, depending on the compound. The limits of detection （LODs） （S/N = 3） were ranged from 0.1 to 0.5 ng mL^-1. The method has been successfully applied to the analysis of the pesticide residues in environmental water samples.展开更多
Soybean esterase, a cholinesterase-like enzyme, was purified by differential centrifugation firstly, then, ammonium sulfate precipitation, dialysis, and finally, DEAE-cellulose-32 ion-exchange chromatography after ext...Soybean esterase, a cholinesterase-like enzyme, was purified by differential centrifugation firstly, then, ammonium sulfate precipitation, dialysis, and finally, DEAE-cellulose-32 ion-exchange chromatography after extracting it from soybean seeds with phosphate buffer （0.3 mol L^-1, pH 7.0）. The extract recovery rate of the purified enzyme was 8.18% and purification fold was 91.58. The soybean esterase appeared as two bands on the denaturing SDS-PAGE with molecular weights of 24 and 37.2 kDa, respectively, which proved that it is a dimer protein consisting of two subunits. The result of nondenaturing PAGE revealed that the soybean esterase is a single band with cholinesterase-like activity using α- naphthyl acetate as the substrate and fast blue B salt as coloring agent. The esterase showed very high sensitivity to 18 kinds of organophosphate pesticides and 6 kinds of carbamate pesticides with the lowest detective limits of 0.03125- 0.0625 and 0.03125-0.25 mg kg^-1, respectively, and can meet the demands of MRL specified by the most countries.展开更多
Synthesis of methyl N-phenyl carbamate from dimethyl carbonate and 1,3-diphenyl urea was investigated under atmospheric pressure. The results showed that homogenous catalyst sodium methoxide had the excellent activity...Synthesis of methyl N-phenyl carbamate from dimethyl carbonate and 1,3-diphenyl urea was investigated under atmospheric pressure. The results showed that homogenous catalyst sodium methoxide had the excellent activity to efficiently catalyze the synthesis of methyl N-phenyl carbamate under atmospheric pressure.展开更多
Toxicity-data of two carbamate insecticides, carbaryl and carbofuran, and three fungicides, ziram, zineb and mancozeb with rice-field N2-fixing cyanobacterium Cylindrospermum sp., obtained by in vitro growth and at so...Toxicity-data of two carbamate insecticides, carbaryl and carbofuran, and three fungicides, ziram, zineb and mancozeb with rice-field N2-fixing cyanobacterium Cylindrospermum sp., obtained by in vitro growth and at soil-water interface, were analyzed by the probit method. Growth enhancing concentration, no-observed effective concentration, minimum inhibitory concentration, the highest permissive concentration and lethal concentration100 （LCloo） were determined experimentally. The LC^o values of carbaryl, carbofuran, ziram, zineb and mancozeb in N2-fixing liquid medium were 56.2, 588.8, 0.07, 4.2 and 3.4 IJg/mL, respectively, whereas the corresponding LCloo values were 100.0, 1500.0, 0.17, 25.0 and 9.0 IJg/mL, respectively. The LC50 values of these pesticides in succession in N2-fixing agar medium were 44.7, 239.9, 0.07, 1.8 and 2.3 IJg/mL, respectively, whereas the corresponding LC100 values were 100.0, 600.0, 0.17, 10.0 and 7.0 IJg/mL, respectively. Similar results with nitrate supplemented liquid and agar media indicated that nitrate supplementation had toxicity reducing effect. The LCso and LC^oo values of toxicity in the N2-fixing liquid medium at soil-water interface were 91.2 and 200.0 IJg/mL for carbaryl, 2 317 and 6 000 pg/mL for carbofuran, 0.15 and 0.50 pg/mL for ziram, 16.4 and 50.0 pg/mL for zineb, and 7.2 and 25.0 pg/mL for mancozeb, respectively. Each LC^oo value at soil- water interface with a pesticide was significantly higher than its corresponding LCloo value at liquid/agar media. It can be concluded that, under the N2-fixing conditions, the cyanobacterium tolerated higher levels of each pesticide at soil-water interface.展开更多
Methyl N-phenyl carbamate(MPC), an important organic chemical, can be synthesized from aniline,CO2 and methanol. Catalyst Cu-Fe/ZrO2-SiO2 was first prepared and its catalytic performance for MPC synthesis was evaluate...Methyl N-phenyl carbamate(MPC), an important organic chemical, can be synthesized from aniline,CO2 and methanol. Catalyst Cu-Fe/ZrO2-SiO2 was first prepared and its catalytic performance for MPC synthesis was evaluated. Then the influence of solvent on the reaction path of MPC synthesis was investigated. It is found that the reaction intermediate is different with acetonitrile or methanol as a solvent. With acetonitrile as a solvent,the synthesis of MPC follows the reaction path with diphenyl urea as the intermediate, while with methanol as a solvent the reaction occurs via the reaction path with dimethyl carbonate as the intermediate. The catalytic mechanism of cooperative catalysis comprising metal sites, Lewis acid sites and Lewis base sites is proposed according to different reaction intermediates.展开更多
Wax apple(Syzygium samarangense)has received growing research interest for its high nutritional and medicinal value due to its constituents such as polysaccharide,organic acids,flavonoids,minerals,and other substances...Wax apple(Syzygium samarangense)has received growing research interest for its high nutritional and medicinal value due to its constituents such as polysaccharide,organic acids,flavonoids,minerals,and other substances.In this study,wax apple polysaccharide(WAP)was isolated from this plant and its protective effect against ethyl carbamate(EC)-induced oxidative damage was evaluated in human hepatocytes(L02 cells).Firstly,a series of analyses such as high-performance liquid chromatography(HPLC),high-performance gel permeation chromatography(HPGPC),Fourier transform infrared spectroscopy(FT-IR),gas chromatography/mass spectrometry(GC/MS),and 1H and 13C nuclear magnetic resonance(NMR)were conducted to identify the structure of,in vitro cell experiments were performed to verify the protective effects of WAP against EC-induced cytotoxicity,genotoxicity,and oxidative damage in L02 cells.Our results revealed that WAP is composed of mannose,rhamnose,glucuronic acid,galacturonic acid,glucose,galactose,arabinose,and fucose in a molar ratio of 2.20:3.94:4.45:8.56:8.86:30.82:39.78:1.48.Using a combination of methylation and NMR spectroscopic analysis,the primary structure of WAP was identified as Araf-(1→,Glcp-(1→,→2)-Araf-(1→,→3)-Galp-(1→,→3)-Araf-(1→,and→6)-Galp-(1→.Cell experiments indicated that WAP exhibited significant protective effects on EC-treated L02 cells via suppressing cytotoxicity and genotoxicity,reducing reactive oxygen species(ROS)and O2?-formation,as well as improving mitochondrial membrane potential(MMP)and glutathione(GSH).In a nutshell,WAP has the potential as an important therapeutic agent or supplement for hepatic oxidative damage.Meanwhile,further studies are needed to prove the above effects in vivo at the biological and clinical levels.展开更多
[Objectives ] The paper was to explore enzyme inhibition rate method for rapid detection of organophosphorus and carbamate pesticides in cowpea. [ Methods ] Acetylcholinesterase （ACHE） was added to cowpea extract, t...[Objectives ] The paper was to explore enzyme inhibition rate method for rapid detection of organophosphorus and carbamate pesticides in cowpea. [ Methods ] Acetylcholinesterase （ACHE） was added to cowpea extract, to determine the inhibition rate of extract against enzyme. The influences of different sampiing methods and sampling parts on detection results were compared. [ Results] The positive rate of standard sampling was 18.18% higher than that of non-stand- ard sampling, and the positive rate of samples collected from cowpea tail was 16.67% higher than that collected from other parts. [ Condmions] Enzyme inhibi- tion rate method is suitable for rapid detection of organophosphorus and carbamate pesticides in cowpea.展开更多
Objective:To evaluate the composition of bioactive substances and the antioxidant effects of jujube fruit under gut microbiota fermentation(GMF),and the inhibitory effect on cytotoxicity caused by ethyl carbamate(EC)....Objective:To evaluate the composition of bioactive substances and the antioxidant effects of jujube fruit under gut microbiota fermentation(GMF),and the inhibitory effect on cytotoxicity caused by ethyl carbamate(EC).Methods:Changes in the contents of flavonoids,polyphenols,total sugars,and reducing sugars of jujube fruit after GMF(0,2,6,12,24,and 48 h)were determined.The oxidation resistance of fermented jujube fruits(from 0 to 48 h fermentation)was evaluated using in vitro 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate)(ABTS)and ferric reducing antioxidant power(FRAP)assays.Inhibitory effects of 48 h-fermented jujube fruit at various concentrations(0.25,0.50,1.00,and 2.00 mg/mL)on EC-treated toxicity and DNA damage of Caco-2 cells were estimated using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide(MTT)and nuclear staining assays,respectively.Effects of different concentrations of jujube fruit on EC-treated Caco-2 cells’intracellular reactive oxygen species(ROS),glutathione(GSH)levels,and mitochondrial membrane potential(MMP)were also evaluated.Results:Jujube fruit has rich bioactive components after GMF and shows strong antioxidant capacity.Fermented jujube fruit can inhibit the cytotoxicity and DNA damage of Caco-2 cells caused by EC and reduce intracellular ROS generation,as well as restoring GSH and MMP.Conclusions:Fermented jujube fruit extracts produced by GMF still contain biologically active substances which retain biological activity and antioxidation capabilities.展开更多
Carbamates are important intermediates in the syntheses of pesticides, herbicides, drugs, polyurethane-based polymers, and other fine and commodity chemicals.
We present an efficient, fast and simple strategy of generating the intermediate carbamoyl chlorides from secondary amines using stoichiometric amounts of bis（trichloromethyl）carbonate （BTC） in solution and solven...We present an efficient, fast and simple strategy of generating the intermediate carbamoyl chlorides from secondary amines using stoichiometric amounts of bis（trichloromethyl）carbonate （BTC） in solution and solvent-free conditions with excellent yields. The results obtained showed the yield increasing on whether a base was used. Finally, an efficient and rapid synthesis of variety carbamate derivatives was developed by the reaction with a high variety of different alcohols, phenols, diols and this intermediate at room temperature with grinding and in solvent-free conditions under microwave irradiation. The presence of various safe bases is shown to be effective in reducing the reaction times, increasing the yields and easing purification. The present method does not involve any hazardous phosgene.展开更多
The vapor pressures of n-butyl carbamate were measured in the temperature range from 372.37 K to 479.27 K and fitted with Antoine equation. The compressibility factor of the vapor was calculated with the Virial equati...The vapor pressures of n-butyl carbamate were measured in the temperature range from 372.37 K to 479.27 K and fitted with Antoine equation. The compressibility factor of the vapor was calculated with the Virial equation and the second virial coefficient was determined by the Vetere model. Then the standard enthalpy of vaporization for n-butyl carbamate was estimated. The heat capacity was measured for the solid state(299.39–324.2 K) and liquid state(336.65–453.21 K) by means of adiabatic calorimeter. The standard enthalpy of formation ΔfH[crystal(cr),298.15 K] and standard entropy S(crystal,298.15 K) of the substance were calculated on the basis of the gas-phase standard enthalpy of formation ΔfH(g,298.15 K)and gas-phase standard entropy S(g,298.15 K), which were estimated by the Benson method. The results are acceptable, validated by a thermochemical cycle.展开更多
Carbon dioxide(CO_(2)) is the main greenhouse gas and also an ideal C1 feedstock in organic synthesis because it is abundant,nontoxic,nonflammable,and renewable.The synthesis of organic carbamates using CO_(2) as a ph...Carbon dioxide(CO_(2)) is the main greenhouse gas and also an ideal C1 feedstock in organic synthesis because it is abundant,nontoxic,nonflammable,and renewable.The synthesis of organic carbamates using CO_(2) as a phosgene alternative has attracted extensive attention because of the importance of carbamates in organic synthesis and in the pharmaceutical and agrochemical industries.In recent decades,many multicomponent reaction strategies have been designed for constructing different types of organic carbamate molecules.Most of these methods rely on the in situ generation of carbamate anions from CO_(2) and amines,followed by reactions with other coupling partners.Synthetic strategies for acyclic carbamates include nucleophile‐electrophile coupling,nucleo‐phile‐nucleophile oxidative coupling,difunctionalization of unsaturated hydrocarbons,and C–H bond functionalization.Strategies for the synthesizing cyclic carbamates include carboxylative cyclization of in situ‐generated unsaturated amines and difunctionalization of unsaturated amines with CO_(2) and other electrophilic reagents.This review summarizes the recent advances in the synthesis of organic carbamates from CO_(2) using different multicomponent reaction strategies.Future perspectives and challenges in the incorporation of CO_(2) into carbamates are also presented.展开更多
A facile synthesis of N-methyl-N-aryl carbamates from aromatic amines and dimethyl carbonate (DMC) has been achieved with high yields in the presence of potassium carbonate (K2CO3)and tetrabutylammonium bromide (Bu4NB...A facile synthesis of N-methyl-N-aryl carbamates from aromatic amines and dimethyl carbonate (DMC) has been achieved with high yields in the presence of potassium carbonate (K2CO3)and tetrabutylammonium bromide (Bu4NBr) under solvent-free conditions.展开更多
A series of carbamate-containing sialyltransferase inhibitors were designed and synthesized to simulate phosphate-linked CMP-Neu5Ac.Their inhibitory activities were assayed against recombinant human ST3Gal I and ST6Ga...A series of carbamate-containing sialyltransferase inhibitors were designed and synthesized to simulate phosphate-linked CMP-Neu5Ac.Their inhibitory activities were assayed against recombinant human ST3Gal I and ST6Gal I by using the Schmidt’s HPLC-based assay.The synthetic compound 15 g showed moderate inhibitory activity.These findings implied that carbamate might serve as a bioisosteric replacement for a phosphate group in sialyltransferase inhibitor design to improve the membrane permeability.展开更多
Four 4-monosubstituted pyrimidine pyridyl sulfonylureas were synthesized from pyridinesulfonamide and phenyl pyrimidylcarbamate and screened for herbicidal activities. We also reported a convenient preparation process...Four 4-monosubstituted pyrimidine pyridyl sulfonylureas were synthesized from pyridinesulfonamide and phenyl pyrimidylcarbamate and screened for herbicidal activities. We also reported a convenient preparation process of phenyl pyrimidylcarbamates from pyrimidineamine and phenyl chloroformate.展开更多
A new method was developed for the quantitative determination of the neurotoxic nonprotein amino acid, 3-N-oxalyl-L-2,3-diaminopropioni acid (β-ODAP), its nontoxic α-isomer and other non-protein amino acids in the p...A new method was developed for the quantitative determination of the neurotoxic nonprotein amino acid, 3-N-oxalyl-L-2,3-diaminopropioni acid (β-ODAP), its nontoxic α-isomer and other non-protein amino acids in the plant samples of Lathyrus sativus after derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) by reversed-phase high-performance liquid chromatography (HPLC). 2-Amino butyric acid (ABA) was used as an internal standard.The RP HPLC detection limit for both isomers is 1.8 ng with good response linearity. The results are compared with a colorimetric method.展开更多
A convenient, efficient, one-pot, novel process has been developed for the synthesis of carbamates from corresponding alkyl halides and amines using basic resin/CO2 system.
基金supported by the National Natural Science Foundation of China(32202125)the Science and Technology Plan Project of Shaoxing City,China(2022A12003)the Zhejiang Provincial Natural Science Foundation,China(LY24C200004).
文摘This study investigated the use of raspberry extract(RBE) for mitigating ethyl carbamate(EC) accumulation in Chinese rice wine(Huangjiu), a traditional fermented beverage. It focused on the addition of RBE to the fermentation mash and its effects on EC levels. The results showed a significant reduction in EC production that could be attributed to RBE's role in altering urea and citrulline catabolism and inhibiting arginine metabolism, thus preventing EC precursors from reacting with ethanol. Additionally, RBE enhanced the rice wine's flavor profile, as shown by volatile component and amino acid analysis. This study also explored RBE's impact on the metabolism of arginine by Saccharomyces cerevisiae in a simulated fermentation environment, and found increased arginine, reduced urea and citrulline levels, altered enzyme activities, and gene expression changes in the arginine metabolism and transport pathways. In conclusion, the results clearly demonstrated RBE's efficacy in reducing the EC content in Chinese rice wine, offering valuable insights for EC reduction strategies.
基金the financial support provided by the National Natural Science Foundation of China(Nos.21572163 and 21873074)the Wenzhou Science&Technology Bureau(No.G20210032)。
文摘Nitrene transfer reactions are powerful tools in synthetic organic chemistry.In recent years,transitionmetal catalyzed nitrene transfer reactions with carbamates as the nitrene precursors have been widely pursued.Such species undergoes facile C-H amination,aziridination,and bifunctionalization of alkenes under the catalysis of different transition metals including Rh,Fe,Ru and others,enabling the efficient construction of various nitrogen-containing molecules.In this review,the recent developments in nitrene transfer reactions with carbamates via N-O bond cleavage were introduced based on different types of reaction,and the key mechanistic information and synthetic applications of the methodologies were discussed.
基金The National Basic Research Program(973Program,Grant No.2004CB518904).
文摘Aim To develop a novel selective protection strategy for the synthesis of ribostamycin cyclic carbamate derivatives. Methods Ribostamycin protected by carbobenzoxy group was treated with Nail, to give different protected intermediates under respective controllable cyclization reaction conditions. New ribostamycin derivative was obtained after the cleavage of carbobenzoxy groups. Result The novel selective protection of ribostamycin was achieved by the synthesis of protected intermediates. New ribostamycin derivative was obtained, but showed no expected antibacterial activity. Conclusion Several ribostamycin cyclic carbamate derivatives were obtained by novel selective protection strategy, which shows the practicability and convenience of the protection strategy. But these new ribostamycin derivatives containing cyclic carbamates structure may not be an ideal leading compound for antibiotic activity.
基金supported both by the Natural Science Foundations of Hebei(No.B2008000210)the Scientific Research Foundation of Agricultural University of Hebei.
文摘A novel method for the determination of five carbamate pesticides （metolcarb, carbofuran, carbaryl, isoprocard and diethofencard） in water samples was developed by dispersive liquid-liquid microextraction （DLLME） coupled with high performance liquid chromatography-diode array detector （HPLC-DAD）. Some experimental parameters that influence the extraction efficiency were studied and optimized to obtain the best extraction results. Under the optimum conditions for the method, the calibration curve was linear in the concentration range from 5 to 1000 ng mL^-1 for all the five carbamate pesticides, with the correlation coefficients （r^2） varying from 0.9984 to 0.9994. Good enrichment factors were achieved ranging from 80 to 177- fold, depending on the compound. The limits of detection （LODs） （S/N = 3） were ranged from 0.1 to 0.5 ng mL^-1. The method has been successfully applied to the analysis of the pesticide residues in environmental water samples.
基金the financial supports from the Ministry of Science and Technology of China(2006BAK02A24)the Ministry of Agriculture of China(2007-2011)Xi'an Bureau of Science and Technology,China (GG05112)
文摘Soybean esterase, a cholinesterase-like enzyme, was purified by differential centrifugation firstly, then, ammonium sulfate precipitation, dialysis, and finally, DEAE-cellulose-32 ion-exchange chromatography after extracting it from soybean seeds with phosphate buffer （0.3 mol L^-1, pH 7.0）. The extract recovery rate of the purified enzyme was 8.18% and purification fold was 91.58. The soybean esterase appeared as two bands on the denaturing SDS-PAGE with molecular weights of 24 and 37.2 kDa, respectively, which proved that it is a dimer protein consisting of two subunits. The result of nondenaturing PAGE revealed that the soybean esterase is a single band with cholinesterase-like activity using α- naphthyl acetate as the substrate and fast blue B salt as coloring agent. The esterase showed very high sensitivity to 18 kinds of organophosphate pesticides and 6 kinds of carbamate pesticides with the lowest detective limits of 0.03125- 0.0625 and 0.03125-0.25 mg kg^-1, respectively, and can meet the demands of MRL specified by the most countries.
文摘Synthesis of methyl N-phenyl carbamate from dimethyl carbonate and 1,3-diphenyl urea was investigated under atmospheric pressure. The results showed that homogenous catalyst sodium methoxide had the excellent activity to efficiently catalyze the synthesis of methyl N-phenyl carbamate under atmospheric pressure.
基金supported by an ES project on ‘Cyanobacteria’ (Grant No.21 (0859)/11/EMR-II),from Council of Scientific and Industrial Research (CSIR),New Delhi,India
文摘Toxicity-data of two carbamate insecticides, carbaryl and carbofuran, and three fungicides, ziram, zineb and mancozeb with rice-field N2-fixing cyanobacterium Cylindrospermum sp., obtained by in vitro growth and at soil-water interface, were analyzed by the probit method. Growth enhancing concentration, no-observed effective concentration, minimum inhibitory concentration, the highest permissive concentration and lethal concentration100 （LCloo） were determined experimentally. The LC^o values of carbaryl, carbofuran, ziram, zineb and mancozeb in N2-fixing liquid medium were 56.2, 588.8, 0.07, 4.2 and 3.4 IJg/mL, respectively, whereas the corresponding LCloo values were 100.0, 1500.0, 0.17, 25.0 and 9.0 IJg/mL, respectively. The LC50 values of these pesticides in succession in N2-fixing agar medium were 44.7, 239.9, 0.07, 1.8 and 2.3 IJg/mL, respectively, whereas the corresponding LC100 values were 100.0, 600.0, 0.17, 10.0 and 7.0 IJg/mL, respectively. Similar results with nitrate supplemented liquid and agar media indicated that nitrate supplementation had toxicity reducing effect. The LCso and LC^oo values of toxicity in the N2-fixing liquid medium at soil-water interface were 91.2 and 200.0 IJg/mL for carbaryl, 2 317 and 6 000 pg/mL for carbofuran, 0.15 and 0.50 pg/mL for ziram, 16.4 and 50.0 pg/mL for zineb, and 7.2 and 25.0 pg/mL for mancozeb, respectively. Each LC^oo value at soil- water interface with a pesticide was significantly higher than its corresponding LCloo value at liquid/agar media. It can be concluded that, under the N2-fixing conditions, the cyanobacterium tolerated higher levels of each pesticide at soil-water interface.
基金Supported by the National Natural Science Foundation of China(20976035)the Natural Science Foundation of Tianjin City(12JCYBJC12800)the Key Basic Research Project of Applied Basic Research Plan of Hebei Province(12965642D)
文摘Methyl N-phenyl carbamate(MPC), an important organic chemical, can be synthesized from aniline,CO2 and methanol. Catalyst Cu-Fe/ZrO2-SiO2 was first prepared and its catalytic performance for MPC synthesis was evaluated. Then the influence of solvent on the reaction path of MPC synthesis was investigated. It is found that the reaction intermediate is different with acetonitrile or methanol as a solvent. With acetonitrile as a solvent,the synthesis of MPC follows the reaction path with diphenyl urea as the intermediate, while with methanol as a solvent the reaction occurs via the reaction path with dimethyl carbonate as the intermediate. The catalytic mechanism of cooperative catalysis comprising metal sites, Lewis acid sites and Lewis base sites is proposed according to different reaction intermediates.
基金supported by the Zhejiang Provincial Key R&D Program of China(No.2021C02018)the Open Project of Wencheng Joint Research Center of Big Health Industry of Zhejiang University(No.Zdwc2205),China.
文摘Wax apple(Syzygium samarangense)has received growing research interest for its high nutritional and medicinal value due to its constituents such as polysaccharide,organic acids,flavonoids,minerals,and other substances.In this study,wax apple polysaccharide(WAP)was isolated from this plant and its protective effect against ethyl carbamate(EC)-induced oxidative damage was evaluated in human hepatocytes(L02 cells).Firstly,a series of analyses such as high-performance liquid chromatography(HPLC),high-performance gel permeation chromatography(HPGPC),Fourier transform infrared spectroscopy(FT-IR),gas chromatography/mass spectrometry(GC/MS),and 1H and 13C nuclear magnetic resonance(NMR)were conducted to identify the structure of,in vitro cell experiments were performed to verify the protective effects of WAP against EC-induced cytotoxicity,genotoxicity,and oxidative damage in L02 cells.Our results revealed that WAP is composed of mannose,rhamnose,glucuronic acid,galacturonic acid,glucose,galactose,arabinose,and fucose in a molar ratio of 2.20:3.94:4.45:8.56:8.86:30.82:39.78:1.48.Using a combination of methylation and NMR spectroscopic analysis,the primary structure of WAP was identified as Araf-(1→,Glcp-(1→,→2)-Araf-(1→,→3)-Galp-(1→,→3)-Araf-(1→,and→6)-Galp-(1→.Cell experiments indicated that WAP exhibited significant protective effects on EC-treated L02 cells via suppressing cytotoxicity and genotoxicity,reducing reactive oxygen species(ROS)and O2?-formation,as well as improving mitochondrial membrane potential(MMP)and glutathione(GSH).In a nutshell,WAP has the potential as an important therapeutic agent or supplement for hepatic oxidative damage.Meanwhile,further studies are needed to prove the above effects in vivo at the biological and clinical levels.
文摘[Objectives ] The paper was to explore enzyme inhibition rate method for rapid detection of organophosphorus and carbamate pesticides in cowpea. [ Methods ] Acetylcholinesterase （ACHE） was added to cowpea extract, to determine the inhibition rate of extract against enzyme. The influences of different sampiing methods and sampling parts on detection results were compared. [ Results] The positive rate of standard sampling was 18.18% higher than that of non-stand- ard sampling, and the positive rate of samples collected from cowpea tail was 16.67% higher than that collected from other parts. [ Condmions] Enzyme inhibi- tion rate method is suitable for rapid detection of organophosphorus and carbamate pesticides in cowpea.
基金This work was supported by the National Natural Science Foundation of China(Nos.U1703105 and 21876152)the Lishui Science and Technology Bureau Research Fund(No.2020zdhz01),China.
文摘Objective:To evaluate the composition of bioactive substances and the antioxidant effects of jujube fruit under gut microbiota fermentation(GMF),and the inhibitory effect on cytotoxicity caused by ethyl carbamate(EC).Methods:Changes in the contents of flavonoids,polyphenols,total sugars,and reducing sugars of jujube fruit after GMF(0,2,6,12,24,and 48 h)were determined.The oxidation resistance of fermented jujube fruits(from 0 to 48 h fermentation)was evaluated using in vitro 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate)(ABTS)and ferric reducing antioxidant power(FRAP)assays.Inhibitory effects of 48 h-fermented jujube fruit at various concentrations(0.25,0.50,1.00,and 2.00 mg/mL)on EC-treated toxicity and DNA damage of Caco-2 cells were estimated using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide(MTT)and nuclear staining assays,respectively.Effects of different concentrations of jujube fruit on EC-treated Caco-2 cells’intracellular reactive oxygen species(ROS),glutathione(GSH)levels,and mitochondrial membrane potential(MMP)were also evaluated.Results:Jujube fruit has rich bioactive components after GMF and shows strong antioxidant capacity.Fermented jujube fruit can inhibit the cytotoxicity and DNA damage of Caco-2 cells caused by EC and reduce intracellular ROS generation,as well as restoring GSH and MMP.Conclusions:Fermented jujube fruit extracts produced by GMF still contain biologically active substances which retain biological activity and antioxidation capabilities.
文摘Carbamates are important intermediates in the syntheses of pesticides, herbicides, drugs, polyurethane-based polymers, and other fine and commodity chemicals.
文摘We present an efficient, fast and simple strategy of generating the intermediate carbamoyl chlorides from secondary amines using stoichiometric amounts of bis（trichloromethyl）carbonate （BTC） in solution and solvent-free conditions with excellent yields. The results obtained showed the yield increasing on whether a base was used. Finally, an efficient and rapid synthesis of variety carbamate derivatives was developed by the reaction with a high variety of different alcohols, phenols, diols and this intermediate at room temperature with grinding and in solvent-free conditions under microwave irradiation. The presence of various safe bases is shown to be effective in reducing the reaction times, increasing the yields and easing purification. The present method does not involve any hazardous phosgene.
文摘The vapor pressures of n-butyl carbamate were measured in the temperature range from 372.37 K to 479.27 K and fitted with Antoine equation. The compressibility factor of the vapor was calculated with the Virial equation and the second virial coefficient was determined by the Vetere model. Then the standard enthalpy of vaporization for n-butyl carbamate was estimated. The heat capacity was measured for the solid state(299.39–324.2 K) and liquid state(336.65–453.21 K) by means of adiabatic calorimeter. The standard enthalpy of formation ΔfH[crystal(cr),298.15 K] and standard entropy S(crystal,298.15 K) of the substance were calculated on the basis of the gas-phase standard enthalpy of formation ΔfH(g,298.15 K)and gas-phase standard entropy S(g,298.15 K), which were estimated by the Benson method. The results are acceptable, validated by a thermochemical cycle.
文摘Carbon dioxide(CO_(2)) is the main greenhouse gas and also an ideal C1 feedstock in organic synthesis because it is abundant,nontoxic,nonflammable,and renewable.The synthesis of organic carbamates using CO_(2) as a phosgene alternative has attracted extensive attention because of the importance of carbamates in organic synthesis and in the pharmaceutical and agrochemical industries.In recent decades,many multicomponent reaction strategies have been designed for constructing different types of organic carbamate molecules.Most of these methods rely on the in situ generation of carbamate anions from CO_(2) and amines,followed by reactions with other coupling partners.Synthetic strategies for acyclic carbamates include nucleophile‐electrophile coupling,nucleo‐phile‐nucleophile oxidative coupling,difunctionalization of unsaturated hydrocarbons,and C–H bond functionalization.Strategies for the synthesizing cyclic carbamates include carboxylative cyclization of in situ‐generated unsaturated amines and difunctionalization of unsaturated amines with CO_(2) and other electrophilic reagents.This review summarizes the recent advances in the synthesis of organic carbamates from CO_(2) using different multicomponent reaction strategies.Future perspectives and challenges in the incorporation of CO_(2) into carbamates are also presented.
文摘A facile synthesis of N-methyl-N-aryl carbamates from aromatic amines and dimethyl carbonate (DMC) has been achieved with high yields in the presence of potassium carbonate (K2CO3)and tetrabutylammonium bromide (Bu4NBr) under solvent-free conditions.
基金The National Key R&D Program of China(Grant No.2018YFA0507602)Project of National Science and Technology Major Project(Grant No.2019ZX09301-106)the National Natural Science Foundation of China(Grant No.91853122).
文摘A series of carbamate-containing sialyltransferase inhibitors were designed and synthesized to simulate phosphate-linked CMP-Neu5Ac.Their inhibitory activities were assayed against recombinant human ST3Gal I and ST6Gal I by using the Schmidt’s HPLC-based assay.The synthetic compound 15 g showed moderate inhibitory activity.These findings implied that carbamate might serve as a bioisosteric replacement for a phosphate group in sialyltransferase inhibitor design to improve the membrane permeability.
基金supported by the National Basic Research Program (No.2003CB 114406)the National Natural Science Foundation of China (No.20672062)the Tianjin Natural Science Foundation (No.07JCYBJC01200).
文摘Four 4-monosubstituted pyrimidine pyridyl sulfonylureas were synthesized from pyridinesulfonamide and phenyl pyrimidylcarbamate and screened for herbicidal activities. We also reported a convenient preparation process of phenyl pyrimidylcarbamates from pyrimidineamine and phenyl chloroformate.
文摘A new method was developed for the quantitative determination of the neurotoxic nonprotein amino acid, 3-N-oxalyl-L-2,3-diaminopropioni acid (β-ODAP), its nontoxic α-isomer and other non-protein amino acids in the plant samples of Lathyrus sativus after derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) by reversed-phase high-performance liquid chromatography (HPLC). 2-Amino butyric acid (ABA) was used as an internal standard.The RP HPLC detection limit for both isomers is 1.8 ng with good response linearity. The results are compared with a colorimetric method.
文摘A convenient, efficient, one-pot, novel process has been developed for the synthesis of carbamates from corresponding alkyl halides and amines using basic resin/CO2 system.
