Pectin is a natural polysaccharide with a complex structure consisting of linear and branched regions rich in galacturonic acid.The growing interest in orange peel pectin can be attributed to its abundant supply.Accor...Pectin is a natural polysaccharide with a complex structure consisting of linear and branched regions rich in galacturonic acid.The growing interest in orange peel pectin can be attributed to its abundant supply.According to statistics,about 10 million tons of orange peel waste are produced worldwide each year.Traditionally,the extraction and utilization of pectin have focused on its gelling,thickening,and stabilizing properties in food.However,as more and more research teams have found that pectin has good biocompatibility,biodegradability and easy chemical modification,its potential in drug delivery systems,tissue engineering,and wound healing is gradually being explored.This review focuses on orange peel pectin polysaccharides and discusses its traditional and modern extraction techniques,especially the advanced method of subcritical water extraction.This study also outlines the structural modifications of pectin such as methylation and acetylation,and introduces its antioxidant and anticancer biological activities and their emerging roles in the development of advanced biomaterials such as bone tissue engineering and fibre pad dressings.展开更多
Sensitivity analysis and structural modification techniques are used to investigate the structural modifications of a machine gun tripod which suffers from severe vibration during firing due to the resonance. The fini...Sensitivity analysis and structural modification techniques are used to investigate the structural modifications of a machine gun tripod which suffers from severe vibration during firing due to the resonance. The finite element analysis and modal test techniques are used to determine the natural frequencies of the machine gun. The sensitivities of natural frequencies with respect to the structural parameters of the tripod are obtained by the method of sensitivity analysis, and they can be used as an indication for the structural modification of the tripod so as to shift the natural frequencies effectively. By the structural modification techniques, finally, the optimal structural modifications of the tripod for desired natural frequencies are made to avoid the resonance, and this optimal structural modification is verified by re-analysis of the modified structure and the vibration contrast between original structure and modified structure. The research resulted in a successful structural modification for desired natural frequencies, which can avoid the resonance and thereby greatly improve the shooting precision of the machine gun during firing.展开更多
The quantum anomalous Hall(QAH)effect in two-dimensional(2D)topological materials has attracted widespread attention due to its potential for dissipationless chiral edge transport without an external magnetic field,wh...The quantum anomalous Hall(QAH)effect in two-dimensional(2D)topological materials has attracted widespread attention due to its potential for dissipationless chiral edge transport without an external magnetic field,which is highly promising for low-power electronic applications.However,identifying materials that exhibit these properties remains particularly challenging,as only a limited number of such materials are known,raising the intriguing question of whether it is possible to induce the QAH effect in materials with ordinary properties through structural modifications.In this work,we grow an unreported 2D titanium selenide(Ti_(3)Se_(4))on a Cu(111)substrate using molecular beam epitaxy.Low-energy electron diffraction and scanning tunneling microscopy characterizations reveal a√7×√7 brick-like structure.First-principles calculations and X-ray photoelectron spectroscopy measurements confirm its composition to be Ti_(3)Se_(4).Our calculations further demonstrate that monolayer Ti_(3)Se_(4),in its grown form on Cu(111),has the potential to host the QAH effect.Interestingly,when we examine its freestanding form,the monolayer transitions from a QAH insulator candidate into a conventional semiconductor,despite only minor differences in their atomic structures.This transition enlightens us that subtle lattice adjustments can induce a transition from semiconductor to QAH properties in freestanding Ti_(3)Se_(4).This discovery provides a potential route to engineering practical materials that may exhibit the QAH effect.展开更多
Oleanolic acid(OA),a pentacyclic triterpenoid,exhibits a broad spectrum of biological activities,including antitumor,antiviral,antibacterial,anti-inflammatory,hepatoprotective,hypoglycemic,and hypolipidemic effects.Si...Oleanolic acid(OA),a pentacyclic triterpenoid,exhibits a broad spectrum of biological activities,including antitumor,antiviral,antibacterial,anti-inflammatory,hepatoprotective,hypoglycemic,and hypolipidemic effects.Since its initial isolation and identification,numerous studies have reported on the structural modifications and pharmacological activities of OA and its derivatives.Despite this,there has been a dearth of comprehensive reviews in the past two decades,leading to challenges in subsequent research on OA.Based on the main biological activities of OA,this paper comprehensively summarized the modification strategies and structureactivity relationships(SARs)of OA and its derivatives to provide valuable reference for future investigations into OA.展开更多
Organic small molecule fluorophores have been widely used in biology and biochemistry to study cellular structures and processes at high spatial and temporal resolution.Small-molecule dyes offer various benefits,such ...Organic small molecule fluorophores have been widely used in biology and biochemistry to study cellular structures and processes at high spatial and temporal resolution.Small-molecule dyes offer various benefits,such as high photostability,low molecular weight,and great biocompatibility.However,the poor brightness of most of conventional dyes in biological environments limits their use in high-quality superresolution fluorescence imaging.Chemists have conceived and developed many methods to enhance the brightness of fluorophores,including structural alterations that raise extinction coefficients and quantum yields.This review outlines current attempts and substantial advances achieved by chemists to improve the brightness of organic small-molecule fluorescent dyes,such as scaffold rigidification and twisted intramolecular charge transfer(TICT)inhibition.We think that this review will help researchers understand the chemical mechanisms involved in increasing the brightness of fluorophores for biological applications.展开更多
Podophyllotoxin is a well-studied natural product.Because of its unique structure and ability to inhibit cancer cells,it has been changed in different ways to find out its pharmacological properties.This paper discuss...Podophyllotoxin is a well-studied natural product.Because of its unique structure and ability to inhibit cancer cells,it has been changed in different ways to find out its pharmacological properties.This paper discusses the common chemical modifications of podophyllotoxin molecules,including the C-4 and E-4 site replacements.Furthermore,its common inhibitory effects on cancer cells and antiparasitic activities,among others,are outlined by the connection between conformational changes and pharmacological activities.Importantly,Podophyllotoxin can effectively overcome the phenomenon of multidrug resistance through a dual-targeting mechanism,including inhibition of microtubule protein synthesis and topoisomerase II activity,and induces cell cycle arrest and apoptosis.Recent findings reveal its potential to modulate immune responses through the cyclic GMP-AMP synthase(cGAS)-stimulator of interferon genes(STING)pathway,further extending beyond its classical mechanisms.This study finally provides a systematic summary of the activity ofpodophyllotoxin in common cancer cells,including those in the breast,lung,and prostate.展开更多
Parthenolide(PTL)is a sesquiterpene lactone derived from medicinal plant feverfew(Tanacetum parthenium).Recent studies have demonstrated that it has multiple pharmacological activities,especially in the treatment of v...Parthenolide(PTL)is a sesquiterpene lactone derived from medicinal plant feverfew(Tanacetum parthenium).Recent studies have demonstrated that it has multiple pharmacological activities,especially in the treatment of various hematological and solid cancers.The superior anticancer activity of PTL suggests that it has the potential to be a first-line drug.However,due to the limited physical and chemical properties,as well as bioavailability,structural modification strategies are strongly recommended to improve the anticancer activity.This review describes representative PTL derivatives obtained by different modification strategies,which are reported to exert antiproliferative activities superior to the parent compound PTL.Furthermore,we also summarize their basic mechanisms on cancer-related signaling pathways,so as to explain the potential and characteristics of PTL and its derivatives in cancer therapy.展开更多
Recent development in the modification of ceria-based catalysts for exhaust gas treatment was reviewed with the dependence of redox properties on structural characters of materials. The doping of ceria with different ...Recent development in the modification of ceria-based catalysts for exhaust gas treatment was reviewed with the dependence of redox properties on structural characters of materials. The doping of ceria with different cations such as rare earth or transition metal oxides results in improvement of structural stability, catalytic function and resistance to sintering at high temperatures. Aging and reduction treatment at high temperatures promote ceria reduction and is beneficial for oxygen storage capacity of the three-way catalysts. Chemical filing technique is very effective in modifying the redox property in the low temperature regions.展开更多
Under certain conditions, ultrafast pulsed laser interaction with matter leads to the formation of self-organized conical as well as periodic surface structures （commonly reffered to as, laser induced periodic surfac...Under certain conditions, ultrafast pulsed laser interaction with matter leads to the formation of self-organized conical as well as periodic surface structures （commonly reffered to as, laser induced periodic surface structures, LIPSS）. The purpose of the present investigations is to explore the effect of fsec laser fluence and ambient environments （Vacuum ＆ 02） on the formation of LIPSS and conical structures on the Ti surface. The surface morphology was investigated by scanning electron microscope （SEM）. The ablation threshold with single and multiple （N = 100） shots and the existence of an incubation effect was demonstrated by SEM investigations for both the vacuum and the 02 environment. The phase analysis and chemical composition of the exposed targets were performed by x-ray diffraction （XRD） and energy dispersive x-ray spectroscopy （EDS）, respectively. SEM investigations reveal the formation of LIPSS （nano ＆ micro）. FFT d-spacing calculations illustrate the dependence of periodicity on the fluence and ambient environment. The periodicity of nano-scale LIPSS is higher in the case of irradiation under vacuum conditions as compared to 02. Furthermore, the 02 environment reduces the ablation threshold. XRD data reveal that for the 02 environment, new phases （oxides of Ti） are formed. EDS analysis exhibits that after irradiation under vacuum conditions, the percentage of impurity element （A1） is reduced. The irradiation in the 02 environment results in 15% atomic diffusion of oxygen.展开更多
Natural steroids have been showing notable cytotoxic activities, which are quite interesting lead compounds for the development of anticancer drug including estramustine and prednimustine. Considering that these semi-...Natural steroids have been showing notable cytotoxic activities, which are quite interesting lead compounds for the development of anticancer drug including estramustine and prednimustine. Considering that these semi-synthetic molecules are nitrogen mustard functionalized steroidal derivatives, the present review is focused on the methodologies of introducing nitrogen atom or nitrogen-containing heterocycles on A^D rings or side chains of steroids, and analysis of the structure-activity relationship（SAR） for these man-made cytotoxic steroids.展开更多
Work-hardening behaviour of type 316 austenitic stainless steel having difFerent initial dislocation structures introduced by swaging to various levels is analysed by a simplified Kock's model which takes into acc...Work-hardening behaviour of type 316 austenitic stainless steel having difFerent initial dislocation structures introduced by swaging to various levels is analysed by a simplified Kock's model which takes into account the structural changes through the dislocation accumulation and annihilation process during deformation. The dislocation accumulation and annihilation factors show a temperature and structure dependence. The dislocation annihilation factor shows a plateau or decreasing tendency in the dynamic strain ageing (DSA) temperature range. This is attributed as either due to dislocation accumulation being more pronounced than dislocation annihilation or as due to precipitates being formed at DSA temperatures acting as obstacles to dislocation motion in the DSA temperature range.展开更多
This paper reviews recent progress in the structural modification and activities on Panax notoginseng saponins(PNS).PNS can not only improve the function of cardio-cerebral system,central nervous system and immune sys...This paper reviews recent progress in the structural modification and activities on Panax notoginseng saponins(PNS).PNS can not only improve the function of cardio-cerebral system,central nervous system and immune system,but also reveal anticancer,anti-aging and anti-oxidation activities.In order to solve the problem of low bioavailability and poor absorbability of PNS in vivo,usually,the researchers modified the structure of PNS with three methods:glycoside cleavage(including acid hydrolysis,sulfation,etc.),biotransformation method(including enzyme hydrolysis,microbial transformation)and combinatorial chemical method.It was found that the structural modification sites of PNS were single,mainly aimed at C-3,C-6 and C-20,which provided a new perspective for the structural modification of PNS.Therefore,structural modification on PNS with high yield and ready availability are significant in the discovery of new active ingredients and industrialization.Derivatives of PNS are applied to research of structure-activity relationship,which is beneficial to the development of new medicines.展开更多
Natural products (NPs) have consistently played a pivotal role in pharmaceutical research, exerting profound impactson the treatment of human diseases. A significant proportion of approved molecular entity drugs are e...Natural products (NPs) have consistently played a pivotal role in pharmaceutical research, exerting profound impactson the treatment of human diseases. A significant proportion of approved molecular entity drugs are either directly derived from NPs orindirectly through modifications of NPs. This review presents an overview of NP drugs recently approved in China, the United States,and other countries, spanning various disease categories, including cancers, cardiovascular and cerebrovascular diseases, centralnervous system disorders, and infectious diseases. The article provides a succinct introduction to the origin, activity, development process, approval details, and mechanism of action of these NP drugs.展开更多
High-temperature proton exchange membranes(HT-PEMs) possess excellent thermal and outstanding electrochemical stability, providing an avenue to realize high-temperature proton exchange membranes fuel cells(HT-PEMFCs) ...High-temperature proton exchange membranes(HT-PEMs) possess excellent thermal and outstanding electrochemical stability, providing an avenue to realize high-temperature proton exchange membranes fuel cells(HT-PEMFCs) with both superior power density and long-term durability. Unfortunately, polybenzimidazole(PBI), a typical material for conventional HT-PEMs, fails to compromise the high nonaqueous proton conductivity and high mechanical properties, thus hindering their practical applications.Achieving efficient nonaqueous proton conduction is crucial for HT-PEMFC, and many insightful research works have been done in this area. However, there still lacks a report that integrates the host-vip interactions of phosphoric acid doping and the structural stability of polymers to systematically illustrate modification strategies. Here, we summarize recent advancements in enhancing the nonaqueous proton conduction of HT-PEMs. Various polymer structure modification strategies, including main chain and side group modification, cross-linking, blocking, and branching, are reviewed. Composite approaches of polymer, including compounding with organic porous polymers, filling the inorganic components and modifying with ionic liquids, etc., are also covered in this work. These strategies endow the HT-PEMs with more free volume, nanophase-separated structure, and multi-stage proton transfer channels, which can facilitate the proton transportation and improve their performance. Finally, current challenges and future directions for further enhancements are also outlined.展开更多
The development of high-energy and long-lifespan NASICON-type cathode materials for sodium-ion batteries has always been a research hotspot but a daunting challenge.Although Na_(4)MnCr(PO_(4))_(3)has emerged as one of...The development of high-energy and long-lifespan NASICON-type cathode materials for sodium-ion batteries has always been a research hotspot but a daunting challenge.Although Na_(4)MnCr(PO_(4))_(3)has emerged as one of the most promising high-energy-density cathode materials owing to its three-electron reactions,it still suffers from serious structural distortion upon repetitive charge/discharge processes caused by the Jahn-Teller active Mn^(3+).Herein,the selective substitution of Cr by Zr in Na_(4)MnCr(PO_(4))_(3)was explored to enhance the structural stability,due to the pinning effect of Zr ions and the≈2.9-electron reactions,as-prepared Na_(3.9)MnCr_(0.9)Zr_(0.1)(PO_(4))_(3)/C delivers a high capacity retention of 85.94%over 500 cycles at 5 C and an ultrahigh capacity of 156.4 mAh g^(-1)at 0.1 C,enabling the stable energy output as high as 555.2 Wh kg^(-1).Moreover,during the whole charge/discharge process,a small volume change of only 6.7%was verified by in situ X-ray diffraction,and the reversible reactions of Cr^(3+)/Cr^(4+),Mn^(3+)/Mn^(4+),and Mn^(2+)/Mn^(3+)redox couples were identified via ex situ X-ray photoelectron spectroscopy analyses.Galvanostatic intermittent titration technique tests and density functional theory calculations further demonstrated the fast reaction kinetics of the Na_(3.9)MnCr_(0.9)Zr_(0.1)(PO_(4))_(3)/C electrode.This work offers new opportunities for designing high-energy and high-stability NASICON cathodes by ion doping.展开更多
Objective To modify the double bonds and hydroxyl groups of marine natural product brefeldin A(1),derivatives 2~10 were prepared and their inhibitory activities against lung adenocarcinoma epithelial A549 were evaluat...Objective To modify the double bonds and hydroxyl groups of marine natural product brefeldin A(1),derivatives 2~10 were prepared and their inhibitory activities against lung adenocarcinoma epithelial A549 were evaluated.Methods The cytotoxic activities of all derivatives(2~10)against lung adenocarcinoma epithelial A549 were evaluated using MTT assay.Conclusion Derivatives 2~7 and 8~10 were designed and synthesized via introducing sulfur atoms and acetylation into the structure of 1,respectively.All derivatives can inhibit the growth of A549 cells below 1μmol/L,among which derivatives 5 and 9 exhibited significant activities,with IC50 values of 40 nM and 98 nM respectively,which can be used as potential anticancer lead compounds.展开更多
Abstract： In the present study, we developed a simple approach for the structural modifications ofkaempferol （1）. A new compound, 3,5-dihydroxy-2-（4-hydroxyphenyl）-6,8,8-tris（3-methylbut-2-en-1-yl）-4H-chromene-...Abstract： In the present study, we developed a simple approach for the structural modifications ofkaempferol （1）. A new compound, 3,5-dihydroxy-2-（4-hydroxyphenyl）-6,8,8-tris（3-methylbut-2-en-1-yl）-4H-chromene-4,7（SH）-dione （5） together with three known compounds, 8-prenylkaempferol （Z）, 6-prenylkaempferol （3） and 6,8-diprenylkaempferol （4）, were synthesized under different reaction conditions. All of derivatives were synthesized in a structural modification way for the first time. Their structures were primarily elucidated by NMR and MS analyses. Compounds 2, 3 and 5 exhibited prominent cytotoxic activity against MDA-231 （IC50 values were 9.45±0.20 μM, 7.15±0.37 μM and 6.92±0.30 μM, respectively） and MCF-7 （ICso values were 10.08±0.57 0M, 10.04±0.23 μM and 2.15±0.20 μM, respectively） breast cancer cells.展开更多
Phenalenone is a kind of defensive compound biosynthesized inside plants in response to the outside attack such as fungus and nematodes.A set of derivatives encompassing structural modifications on the privileged phen...Phenalenone is a kind of defensive compound biosynthesized inside plants in response to the outside attack such as fungus and nematodes.A set of derivatives encompassing structural modifications on the privileged phenalenone scaffold were synthesized through introduction of phenyl and hydroxy!substitutes at 9-positon and 2-position and assessed their insecticidal activities against armyworm（Mythimna separata Walker） and cowpea aphids[Aphis craccivora）.No obvious insecticidal activities of the synthesized compounds were observed against armyworm.Some of the 9-phenyl and 2-hydroxy substituted phenalenone analogues showed potential activities against cowpea aphids with 33%-41%mortality at 500 mg/L.展开更多
To find new pesticide candidates,by using of a natural product andrographolide as the precursor,a series of novel indolo[2,3-b]andrographolide derivatives were semisynthesized by Fischer-indole rearrangement reaction....To find new pesticide candidates,by using of a natural product andrographolide as the precursor,a series of novel indolo[2,3-b]andrographolide derivatives were semisynthesized by Fischer-indole rearrangement reaction.Their structures were identified by 1H NMR,IR,mp,and HRMS,and the steric configuration of compound Ic was further determined on single-crystal analysis.Compounds If and IIb showed 5.9 and 7.0 times potent acaricidal activity compared to andrographolide against Tetranychus cinnabarinus.Compound Ib displayed 4.2 folds higher aphicidal activity compared to andrographolide against Eriosoma lanigerum.In addition,the pronounced insecticidal activity of compound IIc against Aphis citricola was 4.2 folds of that of andrographolide.Scanning electron microscopy revealed that compound IIb can destroy the epidermis of T.cinnabarinus.These results can provide a basis for future research on botanical agrochemicals.展开更多
文摘Pectin is a natural polysaccharide with a complex structure consisting of linear and branched regions rich in galacturonic acid.The growing interest in orange peel pectin can be attributed to its abundant supply.According to statistics,about 10 million tons of orange peel waste are produced worldwide each year.Traditionally,the extraction and utilization of pectin have focused on its gelling,thickening,and stabilizing properties in food.However,as more and more research teams have found that pectin has good biocompatibility,biodegradability and easy chemical modification,its potential in drug delivery systems,tissue engineering,and wound healing is gradually being explored.This review focuses on orange peel pectin polysaccharides and discusses its traditional and modern extraction techniques,especially the advanced method of subcritical water extraction.This study also outlines the structural modifications of pectin such as methylation and acetylation,and introduces its antioxidant and anticancer biological activities and their emerging roles in the development of advanced biomaterials such as bone tissue engineering and fibre pad dressings.
文摘Sensitivity analysis and structural modification techniques are used to investigate the structural modifications of a machine gun tripod which suffers from severe vibration during firing due to the resonance. The finite element analysis and modal test techniques are used to determine the natural frequencies of the machine gun. The sensitivities of natural frequencies with respect to the structural parameters of the tripod are obtained by the method of sensitivity analysis, and they can be used as an indication for the structural modification of the tripod so as to shift the natural frequencies effectively. By the structural modification techniques, finally, the optimal structural modifications of the tripod for desired natural frequencies are made to avoid the resonance, and this optimal structural modification is verified by re-analysis of the modified structure and the vibration contrast between original structure and modified structure. The research resulted in a successful structural modification for desired natural frequencies, which can avoid the resonance and thereby greatly improve the shooting precision of the machine gun during firing.
基金financial support from the National Key R&D Program of China(Nos.2019YFA0308500 and 2018YFA0305800)the National Natural Science Foundation of China(Nos.61925111,61888102,11974422,and U23A6015)+3 种基金CAS Project for Young Scientists in Basic Research(No.YSBR-003)the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDB28000000 and XDB30000000)the Fundamental Research Funds for the Central Universities provided to University of Chinese Academy of Sciences and to Renmin University of China(No.22XNKJ30(W.J.))the CAS Key Laboratory of Vacuum Physics.
文摘The quantum anomalous Hall(QAH)effect in two-dimensional(2D)topological materials has attracted widespread attention due to its potential for dissipationless chiral edge transport without an external magnetic field,which is highly promising for low-power electronic applications.However,identifying materials that exhibit these properties remains particularly challenging,as only a limited number of such materials are known,raising the intriguing question of whether it is possible to induce the QAH effect in materials with ordinary properties through structural modifications.In this work,we grow an unreported 2D titanium selenide(Ti_(3)Se_(4))on a Cu(111)substrate using molecular beam epitaxy.Low-energy electron diffraction and scanning tunneling microscopy characterizations reveal a√7×√7 brick-like structure.First-principles calculations and X-ray photoelectron spectroscopy measurements confirm its composition to be Ti_(3)Se_(4).Our calculations further demonstrate that monolayer Ti_(3)Se_(4),in its grown form on Cu(111),has the potential to host the QAH effect.Interestingly,when we examine its freestanding form,the monolayer transitions from a QAH insulator candidate into a conventional semiconductor,despite only minor differences in their atomic structures.This transition enlightens us that subtle lattice adjustments can induce a transition from semiconductor to QAH properties in freestanding Ti_(3)Se_(4).This discovery provides a potential route to engineering practical materials that may exhibit the QAH effect.
基金supported by the Lianyungang Postdoctoral Research Funding Program(No.LYG20210018).
文摘Oleanolic acid(OA),a pentacyclic triterpenoid,exhibits a broad spectrum of biological activities,including antitumor,antiviral,antibacterial,anti-inflammatory,hepatoprotective,hypoglycemic,and hypolipidemic effects.Since its initial isolation and identification,numerous studies have reported on the structural modifications and pharmacological activities of OA and its derivatives.Despite this,there has been a dearth of comprehensive reviews in the past two decades,leading to challenges in subsequent research on OA.Based on the main biological activities of OA,this paper comprehensively summarized the modification strategies and structureactivity relationships(SARs)of OA and its derivatives to provide valuable reference for future investigations into OA.
基金supported by the National Science Foundation for Distinguished Young Scholars(No.22325401)the National Natural Science Foundation of China(No.22404049)the China Postdoctoral Science Foundation(No.2024M750866)。
文摘Organic small molecule fluorophores have been widely used in biology and biochemistry to study cellular structures and processes at high spatial and temporal resolution.Small-molecule dyes offer various benefits,such as high photostability,low molecular weight,and great biocompatibility.However,the poor brightness of most of conventional dyes in biological environments limits their use in high-quality superresolution fluorescence imaging.Chemists have conceived and developed many methods to enhance the brightness of fluorophores,including structural alterations that raise extinction coefficients and quantum yields.This review outlines current attempts and substantial advances achieved by chemists to improve the brightness of organic small-molecule fluorescent dyes,such as scaffold rigidification and twisted intramolecular charge transfer(TICT)inhibition.We think that this review will help researchers understand the chemical mechanisms involved in increasing the brightness of fluorophores for biological applications.
基金funded by FDCT grants from Macao Science and Technology University to PC(Project Code:0005-2023-RIA1)。
文摘Podophyllotoxin is a well-studied natural product.Because of its unique structure and ability to inhibit cancer cells,it has been changed in different ways to find out its pharmacological properties.This paper discusses the common chemical modifications of podophyllotoxin molecules,including the C-4 and E-4 site replacements.Furthermore,its common inhibitory effects on cancer cells and antiparasitic activities,among others,are outlined by the connection between conformational changes and pharmacological activities.Importantly,Podophyllotoxin can effectively overcome the phenomenon of multidrug resistance through a dual-targeting mechanism,including inhibition of microtubule protein synthesis and topoisomerase II activity,and induces cell cycle arrest and apoptosis.Recent findings reveal its potential to modulate immune responses through the cyclic GMP-AMP synthase(cGAS)-stimulator of interferon genes(STING)pathway,further extending beyond its classical mechanisms.This study finally provides a systematic summary of the activity ofpodophyllotoxin in common cancer cells,including those in the breast,lung,and prostate.
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20201332)the“Double First-Class”University Project(No.CPU2018GF03)+1 种基金the Six Talent Peaks Project of Jiangsu Province(No.SWYY-107)Jiangsu Province‘333’Project,111 Center from Ministry of Education of China and the State Administration of Foreign Experts Affairs of China(No.B18056).
文摘Parthenolide(PTL)is a sesquiterpene lactone derived from medicinal plant feverfew(Tanacetum parthenium).Recent studies have demonstrated that it has multiple pharmacological activities,especially in the treatment of various hematological and solid cancers.The superior anticancer activity of PTL suggests that it has the potential to be a first-line drug.However,due to the limited physical and chemical properties,as well as bioavailability,structural modification strategies are strongly recommended to improve the anticancer activity.This review describes representative PTL derivatives obtained by different modification strategies,which are reported to exert antiproliferative activities superior to the parent compound PTL.Furthermore,we also summarize their basic mechanisms on cancer-related signaling pathways,so as to explain the potential and characteristics of PTL and its derivatives in cancer therapy.
文摘Recent development in the modification of ceria-based catalysts for exhaust gas treatment was reviewed with the dependence of redox properties on structural characters of materials. The doping of ceria with different cations such as rare earth or transition metal oxides results in improvement of structural stability, catalytic function and resistance to sintering at high temperatures. Aging and reduction treatment at high temperatures promote ceria reduction and is beneficial for oxygen storage capacity of the three-way catalysts. Chemical filing technique is very effective in modifying the redox property in the low temperature regions.
文摘Under certain conditions, ultrafast pulsed laser interaction with matter leads to the formation of self-organized conical as well as periodic surface structures （commonly reffered to as, laser induced periodic surface structures, LIPSS）. The purpose of the present investigations is to explore the effect of fsec laser fluence and ambient environments （Vacuum ＆ 02） on the formation of LIPSS and conical structures on the Ti surface. The surface morphology was investigated by scanning electron microscope （SEM）. The ablation threshold with single and multiple （N = 100） shots and the existence of an incubation effect was demonstrated by SEM investigations for both the vacuum and the 02 environment. The phase analysis and chemical composition of the exposed targets were performed by x-ray diffraction （XRD） and energy dispersive x-ray spectroscopy （EDS）, respectively. SEM investigations reveal the formation of LIPSS （nano ＆ micro）. FFT d-spacing calculations illustrate the dependence of periodicity on the fluence and ambient environment. The periodicity of nano-scale LIPSS is higher in the case of irradiation under vacuum conditions as compared to 02. Furthermore, the 02 environment reduces the ablation threshold. XRD data reveal that for the 02 environment, new phases （oxides of Ti） are formed. EDS analysis exhibits that after irradiation under vacuum conditions, the percentage of impurity element （A1） is reduced. The irradiation in the 02 environment results in 15% atomic diffusion of oxygen.
基金Financial support from the National Natural Science Foundation of China(No.21272136)Youth Talent Development Foundation of China Three Gorges University
文摘Natural steroids have been showing notable cytotoxic activities, which are quite interesting lead compounds for the development of anticancer drug including estramustine and prednimustine. Considering that these semi-synthetic molecules are nitrogen mustard functionalized steroidal derivatives, the present review is focused on the methodologies of introducing nitrogen atom or nitrogen-containing heterocycles on A^D rings or side chains of steroids, and analysis of the structure-activity relationship（SAR） for these man-made cytotoxic steroids.
文摘Work-hardening behaviour of type 316 austenitic stainless steel having difFerent initial dislocation structures introduced by swaging to various levels is analysed by a simplified Kock's model which takes into account the structural changes through the dislocation accumulation and annihilation process during deformation. The dislocation accumulation and annihilation factors show a temperature and structure dependence. The dislocation annihilation factor shows a plateau or decreasing tendency in the dynamic strain ageing (DSA) temperature range. This is attributed as either due to dislocation accumulation being more pronounced than dislocation annihilation or as due to precipitates being formed at DSA temperatures acting as obstacles to dislocation motion in the DSA temperature range.
基金Supported by High-level Talent Training Program for Graduate Students of Tibet University(2020-GSP-B014)National Natural Science Foundation of China(81560589)Yunnan Provincial Department of Science and Technology-Kunming Medical University Applied Basic Research Joint Special Fund(2017FE468-001)。
文摘This paper reviews recent progress in the structural modification and activities on Panax notoginseng saponins(PNS).PNS can not only improve the function of cardio-cerebral system,central nervous system and immune system,but also reveal anticancer,anti-aging and anti-oxidation activities.In order to solve the problem of low bioavailability and poor absorbability of PNS in vivo,usually,the researchers modified the structure of PNS with three methods:glycoside cleavage(including acid hydrolysis,sulfation,etc.),biotransformation method(including enzyme hydrolysis,microbial transformation)and combinatorial chemical method.It was found that the structural modification sites of PNS were single,mainly aimed at C-3,C-6 and C-20,which provided a new perspective for the structural modification of PNS.Therefore,structural modification on PNS with high yield and ready availability are significant in the discovery of new active ingredients and industrialization.Derivatives of PNS are applied to research of structure-activity relationship,which is beneficial to the development of new medicines.
基金supported by National Natural Science Foundation of China(No.32170406).
文摘Natural products (NPs) have consistently played a pivotal role in pharmaceutical research, exerting profound impactson the treatment of human diseases. A significant proportion of approved molecular entity drugs are either directly derived from NPs orindirectly through modifications of NPs. This review presents an overview of NP drugs recently approved in China, the United States,and other countries, spanning various disease categories, including cancers, cardiovascular and cerebrovascular diseases, centralnervous system disorders, and infectious diseases. The article provides a succinct introduction to the origin, activity, development process, approval details, and mechanism of action of these NP drugs.
基金supported by the Science Foundation of National Key Laboratory of Science and Technology on Advanced Composites in Special Environmentsthe National Natural Science Foundation of China (No.12002109)+1 种基金sponsored by Natural Science Foundation of Chongqing, China (Nos.CSTC2021jcyj-msxm X10305, CSTB2022NSCQMSX0246, CSTB2022NSCQ-MSX0242, CSTB2022NSCQMSX1244, CSTB2022NSCQ-MSX0441, CSTB2022NSCQMSX1356, CSTB2022NSCQ-MSX1572, CSTB2022NSCQ-MSX1583, CSTB2022NSCQ-MSX0487, CSTB2022TFII-OFX0034)Chongqing Technology Innovation and Application Development Special Key Project (No.CSTB2023TIAD-KPX0010)。
文摘High-temperature proton exchange membranes(HT-PEMs) possess excellent thermal and outstanding electrochemical stability, providing an avenue to realize high-temperature proton exchange membranes fuel cells(HT-PEMFCs) with both superior power density and long-term durability. Unfortunately, polybenzimidazole(PBI), a typical material for conventional HT-PEMs, fails to compromise the high nonaqueous proton conductivity and high mechanical properties, thus hindering their practical applications.Achieving efficient nonaqueous proton conduction is crucial for HT-PEMFC, and many insightful research works have been done in this area. However, there still lacks a report that integrates the host-vip interactions of phosphoric acid doping and the structural stability of polymers to systematically illustrate modification strategies. Here, we summarize recent advancements in enhancing the nonaqueous proton conduction of HT-PEMs. Various polymer structure modification strategies, including main chain and side group modification, cross-linking, blocking, and branching, are reviewed. Composite approaches of polymer, including compounding with organic porous polymers, filling the inorganic components and modifying with ionic liquids, etc., are also covered in this work. These strategies endow the HT-PEMs with more free volume, nanophase-separated structure, and multi-stage proton transfer channels, which can facilitate the proton transportation and improve their performance. Finally, current challenges and future directions for further enhancements are also outlined.
基金Financial support from the National Natural Science Foundation of China(22075016 and 22103057)Fundamental Research Funds for the Central Universities(FRF-TP-20-020A3 and QNXM20220060)+1 种基金Interdisciplinary Research Project for Young Teachers of USTB(FRF-IDRY-21-011)111 Project(B170003 and B12015)
文摘The development of high-energy and long-lifespan NASICON-type cathode materials for sodium-ion batteries has always been a research hotspot but a daunting challenge.Although Na_(4)MnCr(PO_(4))_(3)has emerged as one of the most promising high-energy-density cathode materials owing to its three-electron reactions,it still suffers from serious structural distortion upon repetitive charge/discharge processes caused by the Jahn-Teller active Mn^(3+).Herein,the selective substitution of Cr by Zr in Na_(4)MnCr(PO_(4))_(3)was explored to enhance the structural stability,due to the pinning effect of Zr ions and the≈2.9-electron reactions,as-prepared Na_(3.9)MnCr_(0.9)Zr_(0.1)(PO_(4))_(3)/C delivers a high capacity retention of 85.94%over 500 cycles at 5 C and an ultrahigh capacity of 156.4 mAh g^(-1)at 0.1 C,enabling the stable energy output as high as 555.2 Wh kg^(-1).Moreover,during the whole charge/discharge process,a small volume change of only 6.7%was verified by in situ X-ray diffraction,and the reversible reactions of Cr^(3+)/Cr^(4+),Mn^(3+)/Mn^(4+),and Mn^(2+)/Mn^(3+)redox couples were identified via ex situ X-ray photoelectron spectroscopy analyses.Galvanostatic intermittent titration technique tests and density functional theory calculations further demonstrated the fast reaction kinetics of the Na_(3.9)MnCr_(0.9)Zr_(0.1)(PO_(4))_(3)/C electrode.This work offers new opportunities for designing high-energy and high-stability NASICON cathodes by ion doping.
文摘Objective To modify the double bonds and hydroxyl groups of marine natural product brefeldin A(1),derivatives 2~10 were prepared and their inhibitory activities against lung adenocarcinoma epithelial A549 were evaluated.Methods The cytotoxic activities of all derivatives(2~10)against lung adenocarcinoma epithelial A549 were evaluated using MTT assay.Conclusion Derivatives 2~7 and 8~10 were designed and synthesized via introducing sulfur atoms and acetylation into the structure of 1,respectively.All derivatives can inhibit the growth of A549 cells below 1μmol/L,among which derivatives 5 and 9 exhibited significant activities,with IC50 values of 40 nM and 98 nM respectively,which can be used as potential anticancer lead compounds.
基金National Key Technology R&D Program“New Drug Innovation”of China(Grant No.2013ZX09103002-006)National Natural Science Foundation of China(Grant No.81673590)
文摘Abstract： In the present study, we developed a simple approach for the structural modifications ofkaempferol （1）. A new compound, 3,5-dihydroxy-2-（4-hydroxyphenyl）-6,8,8-tris（3-methylbut-2-en-1-yl）-4H-chromene-4,7（SH）-dione （5） together with three known compounds, 8-prenylkaempferol （Z）, 6-prenylkaempferol （3） and 6,8-diprenylkaempferol （4）, were synthesized under different reaction conditions. All of derivatives were synthesized in a structural modification way for the first time. Their structures were primarily elucidated by NMR and MS analyses. Compounds 2, 3 and 5 exhibited prominent cytotoxic activity against MDA-231 （IC50 values were 9.45±0.20 μM, 7.15±0.37 μM and 6.92±0.30 μM, respectively） and MCF-7 （ICso values were 10.08±0.57 0M, 10.04±0.23 μM and 2.15±0.20 μM, respectively） breast cancer cells.
基金financial supported by National Natural Science Foundation of China(Nos.21472046,21372079)Science and Technology Commission of Shanghai Municipality(No.16391902300)
文摘Phenalenone is a kind of defensive compound biosynthesized inside plants in response to the outside attack such as fungus and nematodes.A set of derivatives encompassing structural modifications on the privileged phenalenone scaffold were synthesized through introduction of phenyl and hydroxy!substitutes at 9-positon and 2-position and assessed their insecticidal activities against armyworm（Mythimna separata Walker） and cowpea aphids[Aphis craccivora）.No obvious insecticidal activities of the synthesized compounds were observed against armyworm.Some of the 9-phenyl and 2-hydroxy substituted phenalenone analogues showed potential activities against cowpea aphids with 33%-41%mortality at 500 mg/L.
基金supported by the National Natural Science Foundation of China(Project No.32072442).
文摘To find new pesticide candidates,by using of a natural product andrographolide as the precursor,a series of novel indolo[2,3-b]andrographolide derivatives were semisynthesized by Fischer-indole rearrangement reaction.Their structures were identified by 1H NMR,IR,mp,and HRMS,and the steric configuration of compound Ic was further determined on single-crystal analysis.Compounds If and IIb showed 5.9 and 7.0 times potent acaricidal activity compared to andrographolide against Tetranychus cinnabarinus.Compound Ib displayed 4.2 folds higher aphicidal activity compared to andrographolide against Eriosoma lanigerum.In addition,the pronounced insecticidal activity of compound IIc against Aphis citricola was 4.2 folds of that of andrographolide.Scanning electron microscopy revealed that compound IIb can destroy the epidermis of T.cinnabarinus.These results can provide a basis for future research on botanical agrochemicals.
