The structure-performance relationship of Cu/Al_(2)O_(3) catalysts in the hydrogenation of diethyl oxalate(DEO)for the synthesis of alcohol ether esters has been investigated by various characterization techniques inc...The structure-performance relationship of Cu/Al_(2)O_(3) catalysts in the hydrogenation of diethyl oxalate(DEO)for the synthesis of alcohol ether esters has been investigated by various characterization techniques including XRD,XPS,N2O titration,and 27Al MAS-NMR.The results showed that when the crystal configurations of Al_(2)O_(3) were the same,increasing the specific surface area could effectively refine the size of copper nanoparticles(Cu NPs),and ultimately improve the conversion of DEO.Meanwhile,the smaller size ofγ-Al_(2)O_(3)(HSAl and SBAl)loaded Cu NPs promotes the reaction towards the deep hydrogenation to produce ethanol(EtOH)and ethylene glycol(EG).Besides,the larger size of Cu NPs on the surface of amorphous Al_(2)O_(3)(HTAl and SolAl)resulted in a lower conversion rate,where ethyl glycolate(Egly)is the main product.Despite there are differences in Al^(3+)ionic coordination in Al_(2)O_(3) with different crystal structures,the experimental data showed that the differences in Al^(3+)ionic coordination did not significantly affect the catalytic performance in the hydrogenation reaction.The formation of alcohol-ether ester chemicals is critically dependent on the interactions between Cu sites and acidic sites.Among them,EG and EtOH were dehydrated to form 2-ethoxyethanol via the SN2 mechanism,while Egly and EtOH were reacted to form ethyl ethoxyacetate(EEA)via the SN2 mechanism.This study provides a theoretical basis for the optimization of the coal-based glycol processes to achieve a diversified product portfolio.展开更多
A visible-light-promoted[1+2]cycloaddition of gem-difluoroalkenes with aryl diazo esters provides an efficient and important route to 1,1-difluorocyclopropanes.The reaction conditions are mild,and the operation is ver...A visible-light-promoted[1+2]cycloaddition of gem-difluoroalkenes with aryl diazo esters provides an efficient and important route to 1,1-difluorocyclopropanes.The reaction conditions are mild,and the operation is very simple.A number of diazo esters and gem-difluoroalkenes are suitable for this reaction(36 examples),providing the desired products in good yields with excellent diastereoselectivity(>20∶1).展开更多
Here,we report a novel nickel-catalyzed electrochemical carboxylation of propargylic esters with CO_(2),characterized by the regioselective synthesis of 2,3-allenoic acids rather than propargylic carboxylic acids.Both...Here,we report a novel nickel-catalyzed electrochemical carboxylation of propargylic esters with CO_(2),characterized by the regioselective synthesis of 2,3-allenoic acids rather than propargylic carboxylic acids.Both acyclic propargylic esters and cyclic propargylic carbonates serve as effective substrates,facilitating the synthesis of mono-,di-,tri-,and tetra-substituted 2,3-allenoic acids with broad substrate scope under mild conditions.Mechanistic investigations indicate that the in situ generated Ni(Ⅰ)complex might serve as the active species to react with propargylic esters,forming the allenyl-Ni(Ⅰ)complex under electroreductive conditions.A possible γ-selective nucleophilic attack of allenyl-Ni(Ⅰ)complex on CO_(2) is likely involved in the formation of the desired 2,3-allenoic acids.展开更多
The catalytic activities of TiSiW_(12)O_(40)/TiO_(2)in synthesizing ethylester;propyl ester,n-butyl ester;and amyl ester were reported.It was demonstrated thatTiSiW_(12)O_(40)/TiO_(2)is an excellent catalyst.Various f...The catalytic activities of TiSiW_(12)O_(40)/TiO_(2)in synthesizing ethylester;propyl ester,n-butyl ester;and amyl ester were reported.It was demonstrated thatTiSiW_(12)O_(40)/TiO_(2)is an excellent catalyst.Various factors concerned with esterification wereinvestigated.The optimum conditions were found:the mole ratio of alcohol to acid is 1.3:1,themass ratio of catalyst to reactants is 1.5 percent,and the reaction time is 1.0 h.Under theoptimum conditions,the yields are 88.0 percent for ethyl ester,94.5 percent for propyl ester,98.6percent for n-butyl ester,99.1 percent for n-amyl ester,and 96.7 percent for iso-amyl ester,respectively.展开更多
Various amino acid esters were reacted with different isothiocyanates in alkaline Al2O3 at room temperature for 1 h affording thiohydantoins in moderate to excellent yields.
An effective route to pyrrolo[1,2-a]pyrazines is described via reaction of ethylenediamine,acetylenic esters and nitrostyrene derivatives in the presence of 20 mol%of sulfamic acid.
Background:In today’s context,vegetable oils,commonly used in culinary practices such as frying and baking,are integral to numerous daily dietary choices.Palm oil,a frequently employed vegetable oil,raises concerns s...Background:In today’s context,vegetable oils,commonly used in culinary practices such as frying and baking,are integral to numerous daily dietary choices.Palm oil,a frequently employed vegetable oil,raises concerns surrounding food safety,thus presenting a significant challenge.Methods:This research aims to enhance consumer awareness regarding the potential health risks associated with 3-monochloropropane-1,2-diol(3-MCPD)and glycidyl fatty acid esters(GEs)commonly found in food and edible oil products.The study endeavours to apprise consumers of these health risks through a comprehensive survey.The survey enlisted the participation of 120 respondents within the age bracket of 18 years to those above 36 years(capped at 50 years).Results:Strikingly,a significant proportion,ranging from 88%to 89%,demonstrated a lack of awareness concerning the potential risks associated with 3-MCPD and GEs in food products.Conclusion:This study underscores the urgency of augmenting consumer's awareness levels regarding 3-MCPD and GEs.Furthermore,it promotes a more detailed examination of Malaysian edible oils and food products available in the market to establish an appropriate Tolerable Daily Intake for the Malaysian population.This research contributes to the broader discourse on food safety and public health by highlighting these crucial facets.展开更多
A highly enantioselective Michael addition of nitro esters to 2-enoyl-pyridine N-oxides was developed by using chiral copper catalysts. The Michael addition products can be obtained in high yields and with up to 96% e...A highly enantioselective Michael addition of nitro esters to 2-enoyl-pyridine N-oxides was developed by using chiral copper catalysts. The Michael addition products can be obtained in high yields and with up to 96% ee. Moreover, asymmetric Michael addition product of nitromethane to 2-enoyl-pyridine N-oxides can be obtained in one step. An analogue of nicotine, dihydro-2H-pyrrol 4b was synthesized with this developed method.展开更多
A simple and efficient synthetic protocol has been developed using a one-pot, three-component reaction involving 2-amino phenols, dialkyl acetylene dicarboxylates and nitrostyrene derivatives. Utilizing this protocol,...A simple and efficient synthetic protocol has been developed using a one-pot, three-component reaction involving 2-amino phenols, dialkyl acetylene dicarboxylates and nitrostyrene derivatives. Utilizing this protocol, a variety of novel pyrrolo-1,4-benzoxazine derivatives were synthesized in excellent yields.展开更多
In our previous work,we found a new method by chance for the synthesis of thiazole derivatives with diversified substitutes on 2-and 5-positions of the thiazole scaffold which was published in Chinese Chemical Letters...In our previous work,we found a new method by chance for the synthesis of thiazole derivatives with diversified substitutes on 2-and 5-positions of the thiazole scaffold which was published in Chinese Chemical Letters[2014,Vol.25 p.411].The structures were identified by ~1H NMR,^（13）C NMR and HRMS as 2-alkoxy-4-amino-Narylthiazole-5-carboxamides.展开更多
We report here a generic,green synthesis of 17 valuable syn-aryl-(2S,3R)-2–chloro-3–hydroxy esters(syn-(2S,3R)-1)in 73%-99%isolated yields along with 6.1:1–83:1 dr and 31%~>99%ee,through dynamic reductive kineti...We report here a generic,green synthesis of 17 valuable syn-aryl-(2S,3R)-2–chloro-3–hydroxy esters(syn-(2S,3R)-1)in 73%-99%isolated yields along with 6.1:1–83:1 dr and 31%~>99%ee,through dynamic reductive kinetic resolution of racemic arylα–chloroβ-keto esters(2)catalyzed by an engineered ketoreductase which was obtained via ep PCR-based directed evolution.The hectogram scale synthesis of syn-(2S,3R)-1b at a substrate concentration of 120 g/L showcased the application potential of the biocatalytic method developed presently.展开更多
Native amino-directed palladium-catalyzed C(sp^(3))-H activation/functionalization has been developed for modification ofα-amino acids and peptides.Herein a palladium(Ⅱ)-catalyzed C(sp^(2))-H arylation ofα-amino-β...Native amino-directed palladium-catalyzed C(sp^(3))-H activation/functionalization has been developed for modification ofα-amino acids and peptides.Herein a palladium(Ⅱ)-catalyzed C(sp^(2))-H arylation ofα-amino-β-aryl esters has been disclosed,using the native amino as the directing group.A variety of chiralα-amino-β-aryl esters can be functionalized to give the corresponding ortho-substituted mono-and di-arylated products.展开更多
Solid acids such as ZrO2 & Mo (VI)/ZrO2 were coated on a honeycomb monolith by impregnation method. These catalytic materials were characterized by NH3-TPD, PXRD and SEM techniques. Salicylate esters were synthesi...Solid acids such as ZrO2 & Mo (VI)/ZrO2 were coated on a honeycomb monolith by impregnation method. These catalytic materials were characterized by NH3-TPD, PXRD and SEM techniques. Salicylate esters were synthesized via transesterification of methyl salicylate with different alcohols over these catalytic materials. An excellent yield of Salicylate esters was obtained under specific reaction conditions. A correlation between the surface acidity, PXRD phase and catalytic activity of Mo (VI)/ZrO2 was observed. The thermally regenerated catalytic material was reused repeatedly with a consistent high yield of salicylate esters. The honeycomb coated with zirconia catalysts were found to be economical, efficient and ecofriendly (3E concept).展开更多
The extraction of Nd^3＋ and Sm^3＋, including the extraction and stripping capability as well as the separation effect of Nd^3＋ or Sm^3＋, from a sulfuric acid medium, by mixtures of di-（2-ethylhexyl） phosphoric a...The extraction of Nd^3＋ and Sm^3＋, including the extraction and stripping capability as well as the separation effect of Nd^3＋ or Sm^3＋, from a sulfuric acid medium, by mixtures of di-（2-ethylhexyl） phosphoric acid （HDEHP, H2A2（0）） and 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester （HEH/EHP, H2L2（0）） were studied. The distribution ratios and synergistic coefficients of Nd^3＋ and Sm^3＋ in different acidities were also determined. A synergistic extractive effect was found when HDEHP and HEH/EHP were used as mixed extractants for Sm^3＋ or Nd^3＋. The chemical compositions of the extracted complex were determined as Nd.（HA2）2-HL2 and Sm.（HA2）2-HL2. The extraction equilibrium constants, enthalpy change, and entropy change of the extraction reaction were also determined.展开更多
Azalomycin F4a 2-ethylpentyl ester,a new 36-membered macrocyclic lactone antibiotic,was isolated from mangrove actinomycete Streptomyces sp.211726.Its structure was elucidated on the basis of spectroscopic data.The co...Azalomycin F4a 2-ethylpentyl ester,a new 36-membered macrocyclic lactone antibiotic,was isolated from mangrove actinomycete Streptomyces sp.211726.Its structure was elucidated on the basis of spectroscopic data.The compound showed broad-spectrum antifungal activity and moderate cytotoxicity against human colon tumor cell HCT-116.展开更多
AIM To investigate the antioxidant effect of caffeic acid phenethyl ester (CAPE) in hepatic stellate cell-T6 (HSC-T6) cells cultured in vitro and the potential mechanisms. METHODS HSC-T6 cells were cultured in vitro a...AIM To investigate the antioxidant effect of caffeic acid phenethyl ester (CAPE) in hepatic stellate cell-T6 (HSC-T6) cells cultured in vitro and the potential mechanisms. METHODS HSC-T6 cells were cultured in vitro and treated with various concentrations of CAPE for 24, 48 and 72 h, respectively. Cell proliferation was investigated using the MTT assay, and cell ultrastructural alterations were observed by transmission electron microscopy. Flow cytometry was employed to investigate the effects of CAPE on apoptosis and the levels of reactive oxygen species in HSC-T6 cells cultured in vitro. An enzyme immunoassay instrument was used to evaluate antioxidant enzyme expression. The effect on alpha-smooth muscle actin was shown using immunofluorescence. Gene and protein levels of Nrf2, related factors, and mitogen activated protein kinases (MAPKs), in HSC-T6 cells were detected using RT-PCR and Western blot, respectively. RESULTS CAPE inhibited the proliferation and activation of HSC-T6 cells cultured in vitro. CAPE increased the antioxidant levels and the translocation of Nrf2 from the cytoplasm to the nucleus in HSC-T6 cells. Moreover, the phosphorylation of MAPKs in cells decreased in response to CAPE. Interestingly, CAPE-induced oxidative stress in the cells was significantly attenuated by pretreatment with MAPKs inhibitors. CONCLUSION CAPE inhibits cell proliferation and up-regulates the antioxidant levels in HSC-T6 cells partly through the Nrf2-MAPKs signaling pathway.展开更多
Ni/Al_2O_3-SiO_2 catalysts were synthesized via one-step method employing SiO_2 as an additive for the selective hydrogenation of butyne-1,4-diol(B_3D) to butane-1,4-diol(B1D). The prepared catalysts were evaluated by...Ni/Al_2O_3-SiO_2 catalysts were synthesized via one-step method employing SiO_2 as an additive for the selective hydrogenation of butyne-1,4-diol(B_3D) to butane-1,4-diol(B1D). The prepared catalysts were evaluated by a series of characterization techniques including BET, XRD, SEM, EDX-mapping, TEM, H_2-TPR, XPS, NH_3-TPD and Py-FTIR. Compared to Ni/Al_2O_3 catalyst, the SiO_2-doped samples exhibited better B_3D conversion. SiO_2 could help to form a strong interaction between NiO with the support, which inhibited Ni agglomeration at high temperature, improved the Ni dispersion, and enhanced the hydrogenation activity. B_1D selectivity was mainly influenced by the quantity of Lewis acid sites in addition to the Ni dispersion. The catalyst with a silica loading of 6.4% demonstrated an excellent selectivity of 75.18%(by 13% higher than the contrastive Ni/Al_2O_3 catalyst), which was attributed to the larger amount of Lewis acid sites and the moderate interaction between NiO with the support, which could facilitate the nickel dispersion on a preferable surface area of 176.3 m^2/g of support.展开更多
文摘The structure-performance relationship of Cu/Al_(2)O_(3) catalysts in the hydrogenation of diethyl oxalate(DEO)for the synthesis of alcohol ether esters has been investigated by various characterization techniques including XRD,XPS,N2O titration,and 27Al MAS-NMR.The results showed that when the crystal configurations of Al_(2)O_(3) were the same,increasing the specific surface area could effectively refine the size of copper nanoparticles(Cu NPs),and ultimately improve the conversion of DEO.Meanwhile,the smaller size ofγ-Al_(2)O_(3)(HSAl and SBAl)loaded Cu NPs promotes the reaction towards the deep hydrogenation to produce ethanol(EtOH)and ethylene glycol(EG).Besides,the larger size of Cu NPs on the surface of amorphous Al_(2)O_(3)(HTAl and SolAl)resulted in a lower conversion rate,where ethyl glycolate(Egly)is the main product.Despite there are differences in Al^(3+)ionic coordination in Al_(2)O_(3) with different crystal structures,the experimental data showed that the differences in Al^(3+)ionic coordination did not significantly affect the catalytic performance in the hydrogenation reaction.The formation of alcohol-ether ester chemicals is critically dependent on the interactions between Cu sites and acidic sites.Among them,EG and EtOH were dehydrated to form 2-ethoxyethanol via the SN2 mechanism,while Egly and EtOH were reacted to form ethyl ethoxyacetate(EEA)via the SN2 mechanism.This study provides a theoretical basis for the optimization of the coal-based glycol processes to achieve a diversified product portfolio.
文摘A visible-light-promoted[1+2]cycloaddition of gem-difluoroalkenes with aryl diazo esters provides an efficient and important route to 1,1-difluorocyclopropanes.The reaction conditions are mild,and the operation is very simple.A number of diazo esters and gem-difluoroalkenes are suitable for this reaction(36 examples),providing the desired products in good yields with excellent diastereoselectivity(>20∶1).
基金financial support from the National Natural Science Foundation of China(Nos.22171090,21871090)National Key Research and Development Program of China(No.2020YFA0710200)+1 种基金the Innovation Program of Shanghai Municipal Education Commission(No.2023ZKZD37)the Fundamental Research Funds for the Central Universities are highly appreciated。
文摘Here,we report a novel nickel-catalyzed electrochemical carboxylation of propargylic esters with CO_(2),characterized by the regioselective synthesis of 2,3-allenoic acids rather than propargylic carboxylic acids.Both acyclic propargylic esters and cyclic propargylic carbonates serve as effective substrates,facilitating the synthesis of mono-,di-,tri-,and tetra-substituted 2,3-allenoic acids with broad substrate scope under mild conditions.Mechanistic investigations indicate that the in situ generated Ni(Ⅰ)complex might serve as the active species to react with propargylic esters,forming the allenyl-Ni(Ⅰ)complex under electroreductive conditions.A possible γ-selective nucleophilic attack of allenyl-Ni(Ⅰ)complex on CO_(2) is likely involved in the formation of the desired 2,3-allenoic acids.
文摘The catalytic activities of TiSiW_(12)O_(40)/TiO_(2)in synthesizing ethylester;propyl ester,n-butyl ester;and amyl ester were reported.It was demonstrated thatTiSiW_(12)O_(40)/TiO_(2)is an excellent catalyst.Various factors concerned with esterification wereinvestigated.The optimum conditions were found:the mole ratio of alcohol to acid is 1.3:1,themass ratio of catalyst to reactants is 1.5 percent,and the reaction time is 1.0 h.Under theoptimum conditions,the yields are 88.0 percent for ethyl ester,94.5 percent for propyl ester,98.6percent for n-butyl ester,99.1 percent for n-amyl ester,and 96.7 percent for iso-amyl ester,respectively.
基金National Natural Science Foundation of China(Grant No.20972005)
文摘Various amino acid esters were reacted with different isothiocyanates in alkaline Al2O3 at room temperature for 1 h affording thiohydantoins in moderate to excellent yields.
文摘An effective route to pyrrolo[1,2-a]pyrazines is described via reaction of ethylenediamine,acetylenic esters and nitrostyrene derivatives in the presence of 20 mol%of sulfamic acid.
文摘Background:In today’s context,vegetable oils,commonly used in culinary practices such as frying and baking,are integral to numerous daily dietary choices.Palm oil,a frequently employed vegetable oil,raises concerns surrounding food safety,thus presenting a significant challenge.Methods:This research aims to enhance consumer awareness regarding the potential health risks associated with 3-monochloropropane-1,2-diol(3-MCPD)and glycidyl fatty acid esters(GEs)commonly found in food and edible oil products.The study endeavours to apprise consumers of these health risks through a comprehensive survey.The survey enlisted the participation of 120 respondents within the age bracket of 18 years to those above 36 years(capped at 50 years).Results:Strikingly,a significant proportion,ranging from 88%to 89%,demonstrated a lack of awareness concerning the potential risks associated with 3-MCPD and GEs in food products.Conclusion:This study underscores the urgency of augmenting consumer's awareness levels regarding 3-MCPD and GEs.Furthermore,it promotes a more detailed examination of Malaysian edible oils and food products available in the market to establish an appropriate Tolerable Daily Intake for the Malaysian population.This research contributes to the broader discourse on food safety and public health by highlighting these crucial facets.
基金financial support from the National Nature Science Foundation of China(Nos. 21432009, 21672200, 21472177,21772185)the assistance of the product characterization from the Chemistry Experiment Teaching Center of University of Science and Technology of Chinasupported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No. XDB20000000)
文摘A highly enantioselective Michael addition of nitro esters to 2-enoyl-pyridine N-oxides was developed by using chiral copper catalysts. The Michael addition products can be obtained in high yields and with up to 96% ee. Moreover, asymmetric Michael addition product of nitromethane to 2-enoyl-pyridine N-oxides can be obtained in one step. An analogue of nicotine, dihydro-2H-pyrrol 4b was synthesized with this developed method.
文摘A simple and efficient synthetic protocol has been developed using a one-pot, three-component reaction involving 2-amino phenols, dialkyl acetylene dicarboxylates and nitrostyrene derivatives. Utilizing this protocol, a variety of novel pyrrolo-1,4-benzoxazine derivatives were synthesized in excellent yields.
文摘In our previous work,we found a new method by chance for the synthesis of thiazole derivatives with diversified substitutes on 2-and 5-positions of the thiazole scaffold which was published in Chinese Chemical Letters[2014,Vol.25 p.411].The structures were identified by ~1H NMR,^（13）C NMR and HRMS as 2-alkoxy-4-amino-Narylthiazole-5-carboxamides.
基金The National Key Research and Development Program of China(Nos.2021YFA0911400 and 2021YFF0600704)the National Natural Science Foundation of China(Nos.22071033 and 21801047)are acknowledged for the financial supports。
文摘We report here a generic,green synthesis of 17 valuable syn-aryl-(2S,3R)-2–chloro-3–hydroxy esters(syn-(2S,3R)-1)in 73%-99%isolated yields along with 6.1:1–83:1 dr and 31%~>99%ee,through dynamic reductive kinetic resolution of racemic arylα–chloroβ-keto esters(2)catalyzed by an engineered ketoreductase which was obtained via ep PCR-based directed evolution.The hectogram scale synthesis of syn-(2S,3R)-1b at a substrate concentration of 120 g/L showcased the application potential of the biocatalytic method developed presently.
基金supported by the National Key Research and Development Program of China(No.2018YFA0704502)the National Natural Science Foundation of China(Nos.21871261,21931011)Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(No.2021ZZ105).
文摘Native amino-directed palladium-catalyzed C(sp^(3))-H activation/functionalization has been developed for modification ofα-amino acids and peptides.Herein a palladium(Ⅱ)-catalyzed C(sp^(2))-H arylation ofα-amino-β-aryl esters has been disclosed,using the native amino as the directing group.A variety of chiralα-amino-β-aryl esters can be functionalized to give the corresponding ortho-substituted mono-and di-arylated products.
文摘Solid acids such as ZrO2 & Mo (VI)/ZrO2 were coated on a honeycomb monolith by impregnation method. These catalytic materials were characterized by NH3-TPD, PXRD and SEM techniques. Salicylate esters were synthesized via transesterification of methyl salicylate with different alcohols over these catalytic materials. An excellent yield of Salicylate esters was obtained under specific reaction conditions. A correlation between the surface acidity, PXRD phase and catalytic activity of Mo (VI)/ZrO2 was observed. The thermally regenerated catalytic material was reused repeatedly with a consistent high yield of salicylate esters. The honeycomb coated with zirconia catalysts were found to be economical, efficient and ecofriendly (3E concept).
基金the National Natural Science Foundation of China (50674016)the National High Technology Research and Develop-ment Program of China (863 Program) ( 2006AA06Z123)
文摘The extraction of Nd^3＋ and Sm^3＋, including the extraction and stripping capability as well as the separation effect of Nd^3＋ or Sm^3＋, from a sulfuric acid medium, by mixtures of di-（2-ethylhexyl） phosphoric acid （HDEHP, H2A2（0）） and 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester （HEH/EHP, H2L2（0）） were studied. The distribution ratios and synergistic coefficients of Nd^3＋ and Sm^3＋ in different acidities were also determined. A synergistic extractive effect was found when HDEHP and HEH/EHP were used as mixed extractants for Sm^3＋ or Nd^3＋. The chemical compositions of the extracted complex were determined as Nd.（HA2）2-HL2 and Sm.（HA2）2-HL2. The extraction equilibrium constants, enthalpy change, and entropy change of the extraction reaction were also determined.
基金supported by The National High Technology Development Project(863)(No. 2007AA09Z415)The National Natural Science Foundation of China(No.U0633008)
文摘Azalomycin F4a 2-ethylpentyl ester,a new 36-membered macrocyclic lactone antibiotic,was isolated from mangrove actinomycete Streptomyces sp.211726.Its structure was elucidated on the basis of spectroscopic data.The compound showed broad-spectrum antifungal activity and moderate cytotoxicity against human colon tumor cell HCT-116.
基金Supported by the Liver Fibrosis Foundation of Wang BaoEn of China,No.20100033the Science and Technology Foundation of Shaanxi Province of China,No.2010K01-199
文摘AIM To investigate the antioxidant effect of caffeic acid phenethyl ester (CAPE) in hepatic stellate cell-T6 (HSC-T6) cells cultured in vitro and the potential mechanisms. METHODS HSC-T6 cells were cultured in vitro and treated with various concentrations of CAPE for 24, 48 and 72 h, respectively. Cell proliferation was investigated using the MTT assay, and cell ultrastructural alterations were observed by transmission electron microscopy. Flow cytometry was employed to investigate the effects of CAPE on apoptosis and the levels of reactive oxygen species in HSC-T6 cells cultured in vitro. An enzyme immunoassay instrument was used to evaluate antioxidant enzyme expression. The effect on alpha-smooth muscle actin was shown using immunofluorescence. Gene and protein levels of Nrf2, related factors, and mitogen activated protein kinases (MAPKs), in HSC-T6 cells were detected using RT-PCR and Western blot, respectively. RESULTS CAPE inhibited the proliferation and activation of HSC-T6 cells cultured in vitro. CAPE increased the antioxidant levels and the translocation of Nrf2 from the cytoplasm to the nucleus in HSC-T6 cells. Moreover, the phosphorylation of MAPKs in cells decreased in response to CAPE. Interestingly, CAPE-induced oxidative stress in the cells was significantly attenuated by pretreatment with MAPKs inhibitors. CONCLUSION CAPE inhibits cell proliferation and up-regulates the antioxidant levels in HSC-T6 cells partly through the Nrf2-MAPKs signaling pathway.
基金Financial support from the National Natural Science Foundation of China (21163019) is gratefully acknowledged
文摘Ni/Al_2O_3-SiO_2 catalysts were synthesized via one-step method employing SiO_2 as an additive for the selective hydrogenation of butyne-1,4-diol(B_3D) to butane-1,4-diol(B1D). The prepared catalysts were evaluated by a series of characterization techniques including BET, XRD, SEM, EDX-mapping, TEM, H_2-TPR, XPS, NH_3-TPD and Py-FTIR. Compared to Ni/Al_2O_3 catalyst, the SiO_2-doped samples exhibited better B_3D conversion. SiO_2 could help to form a strong interaction between NiO with the support, which inhibited Ni agglomeration at high temperature, improved the Ni dispersion, and enhanced the hydrogenation activity. B_1D selectivity was mainly influenced by the quantity of Lewis acid sites in addition to the Ni dispersion. The catalyst with a silica loading of 6.4% demonstrated an excellent selectivity of 75.18%(by 13% higher than the contrastive Ni/Al_2O_3 catalyst), which was attributed to the larger amount of Lewis acid sites and the moderate interaction between NiO with the support, which could facilitate the nickel dispersion on a preferable surface area of 176.3 m^2/g of support.
