Methicillin-resistant Staphylococcus aureus (MRSA), the most common pathogen in hospital and community environments, can cause serious and even fatal infections. The antibiotics currently used for clinical treatment o...Methicillin-resistant Staphylococcus aureus (MRSA), the most common pathogen in hospital and community environments, can cause serious and even fatal infections. The antibiotics currently used for clinical treatment of MRSA have developed resistance, and there is an urgent need to develop new antimicrobials to treat infections caused by MRSA strains. Quinoline analogues play an important role in the development of antimicrobials. Herein, we discussed the current development of antibacterial activities of quinoline analogues, mainly for anti-MRSA activity, and their structure-activity relationships (SARs) from the perspective of using the quinoline nucleus to search for novel potential anti-MRSA candidates. Additionally, the mechanisms of some representative quinoline analogues against MRSA were clarified. Altogether, this review could provide further insights for the rational development of quinoline-based antibacterial drugs, especially against MRSA.展开更多
In searching for effective anticonvulsant agents,fourteen 6-aryl-4.5-di- hydro-3(2H)pyridazinones.fifteen 6-aryl-3(2H)pyridazinones,and seventeen 3-GABA derivatives of 6-aryIpyridazines have been synthesized,and evalu...In searching for effective anticonvulsant agents,fourteen 6-aryl-4.5-di- hydro-3(2H)pyridazinones.fifteen 6-aryl-3(2H)pyridazinones,and seventeen 3-GABA derivatives of 6-aryIpyridazines have been synthesized,and evaluated in mice for the ability to antagonize maximal electroshock seizure(MES).The ED_(50) values showed that 6-(2′,4′- dichlorophenyt)-3(2H)pyridazinone was the most potent anticonvulsant among these corn- pounds(ED_(50)=10.15 mg/kg).The structure-activity relationships of the aryl pyridazinones were studied.The result showed that:(1)the higher the value of the hydrophobic parameter л of the substituent on the phenyl ring.the more potent the anticonvulsant activity of the corn- pound.and(2)only the compounds with an electron withdrawing substituent on the phenyl ring exhibited appreciable anticonvulsant activity.展开更多
Taking the six common anthocyanidins in nature, i.e. cyanidin, delphinidin, malvidin, pelargonidin, peonidin and petunidin, as examples, this paper summarized the main achievements about the structure-activity relatio...Taking the six common anthocyanidins in nature, i.e. cyanidin, delphinidin, malvidin, pelargonidin, peonidin and petunidin, as examples, this paper summarized the main achievements about the structure-activity relationships of the coloration and stability of anthocyanidins. The coloration and stability of anthocyanidins are funda- mentally determined by the chemical and spatial structures of the anthocyanidins. The electron-deficient state, hydroxylation and methylation patterns, especially the ones on the B-ring, and coplanarity of the three rings of anthocyanidins are inde- pendently or synergetically, positively and/or negatively, influence the coloration and stability of the anthocyanidins. Thereinto, the in vivo colorations of anthocyanins are also related to the organ-selective and crystal- or anthocyanic vacuolar inclusion- related existence of the anthocyanidins. This review could provide a reference for the researches of the structure-optimizing and function-exploiting of anthocyanidins and also for the selection of the crops and cultivars containing specific anthocyani- din profiles.展开更多
Aerogels are special porous materials with low thermal conductivity,light weight,high energy absorption rate and large surface area,which have been applied in many fields.However,controlling the aerogel microstructure...Aerogels are special porous materials with low thermal conductivity,light weight,high energy absorption rate and large surface area,which have been applied in many fields.However,controlling the aerogel microstructure remains an academic challenge.Herein,by employing graphene oxide(GO)as the aerogel skeleton and utilizing poly(vinyl alcohol)(PVA)to regulate the ice crystal growth,we elucidate the relationships between the physicochemical properties of GO/PVA aerogel precursors and the nucleation and growth of ice crystals by using an ice-templating method.We demonstrate that due to the hydrogen bond formed between PVA and water molecules,resulting in the initial crystallization temperature being reduced from-12.60℃(GO/PVA-0.01)to-16.21℃(GO/PVA-0.1).Meanwhile,the strong hydrogen bond between PVA and GO limits the diffusion of water molecules,thereby inhibiting the growth of ice crystals,decreasing the pore size of the GO/PVA aerogel from 9.96 nm(GO/PVA-0.01)to 7.19 nm(GO/PVA-0.3),and thus the compressive strength of the aerogel increases from 0.045 MPa to 0.13MPa.Overall,the finding of this study can be extended to other aerogel precursors,and exhibit important scientific value and practical significance for the preparation of aerogel materials with highly controllable structures and performances.展开更多
The growth of Staphylococcus aureus under the action of six kinds of Schiff bases（A,B,C,D,E,F） was studied by means of microcalorimetry. Growth constant k and inhibition ratio I were calculated. Also,the antibacteri...The growth of Staphylococcus aureus under the action of six kinds of Schiff bases（A,B,C,D,E,F） was studied by means of microcalorimetry. Growth constant k and inhibition ratio I were calculated. Also,the antibacterial activity,the action characteristics and the structure-activity relationships of the compounds on S. aureus were analyzed. Results indicate that B,F show good antibacterial activity（IC50：293.6 mg · L-1 and 307.8 mg · L-1） ,D,E show moderate antibacterial activity（IC50：966.3 mg · L-1 and 1 126.7 mg · L-1） ,and A,C just show weak antibacterial activity（IC50 〉1 200 mg · L-1） . The I-c curves mainly present a straight line shape for B,D,E and F,but an inverse ＂S＂ shape for A and C. Structure-activity relationships analysis suggests that the species and position of the substituents determine the antibacterial activity of these Schiff bases,and the charge density distribution is one of the most important influencing factors.展开更多
11β-Hydroxysteroid dehydrogenase 1(11β-HSD1)represents a promising drug target for metabolic syndrome,includ-ing obesity and type 2 diabetes.Our initial screen of a collection of natural products from Danshen led to...11β-Hydroxysteroid dehydrogenase 1(11β-HSD1)represents a promising drug target for metabolic syndrome,includ-ing obesity and type 2 diabetes.Our initial screen of a collection of natural products from Danshen led to the identi-fication of tanshinones as the potent and selective 11β-HSD1 inhibitors.To improve the druggability and explore the structure-activity relationships(SARs),more than 40 derivatives have been designed and synthesized using tanshinone IIA and cryptotanshinone as the starting materials.More than 10 derivatives exhibited potent in vitro 11β-HSD1 inhibitory activity and good selectivity over 11β-HSD2 across human and mouse species.Based on the biological results,SARs were further discussed,which was also partially rationalized by a molecular docking model of 1 bound to the 11β-HSD1.Remarkably,compounds 1,17 and 30 significantly inhibited 11β-HSD1 in 3T3-L1 adipocyte and in livers of ob/ob mice,which merits further investigations as anti-diabetic agents.This study not only provides a series of novel selective 11β-HSD1 inhibitors with promising therapeutic potentials in metabolic syndromes,but also expands the boundaries of the chemical and biological spaces of tanshinones.展开更多
Fatty acids and derivatives(FADs)are resources for natural antimicrobials.In order to screen for additional potent antimicrobial agents,the antimicrobial activities of FADs against Staphylococcus aureus were examined ...Fatty acids and derivatives(FADs)are resources for natural antimicrobials.In order to screen for additional potent antimicrobial agents,the antimicrobial activities of FADs against Staphylococcus aureus were examined using a microplate assay.Monoglycerides of fatty acids were the most potent class of fatty acids,among which monotridecanoin possessed the most potent antimicrobial activity.The conventional quantitative structure-activity relationship(QSAR)and comparative molecular field analysis(CoMFA)were performed to establish two statistically reliable models(conventional QSAR:R2=0.942,Q 2 LOO=0.910;CoMFA:R 2=0.979,Q 2=0.588,respectively).Improved forecasting can be achieved by the combination of these two models that provide a good insight into the structureactivity relationships of the FADs and that may be useful to design new FADs as antimicrobial agents.展开更多
Fentanyl is a potent and widely used clinical narcotic analgesic, as well as a highly selective IJ-opioid agonist. The present study established a homologous model of the human μ-opioid receptor; an intercomparison o...Fentanyl is a potent and widely used clinical narcotic analgesic, as well as a highly selective IJ-opioid agonist. The present study established a homologous model of the human μ-opioid receptor; an intercomparison of three types of μ-opioid receptor protein sequence homologous rates was made. The secondary receptor structure was predicted, the model reliability was assessed and verified using the Ramachandran plot and ProTab analysis. The predictive ability of the CoMFA model was further validated using an external test set. Using the Surflex-Dock program, a series of fentanyl analog molecules were docked to the receptor, the calculation results from Biopolymer/SitelD showed that the receptor had a deep binding area situated in the extracellular side of the transmembrane domains （TM） among TM3, TM5, TM6, and TMT. Results suggested that there might be 5 active areas in the receptor. The important residues were Asp147, Tyr148, and Tyr149 in TM3, Trp293, and His297 in TM6, and Trp318, His319, Ile322, and Tyr326 in TM7, which were located at the 5 active areas. The best fentanyl docking orientation position was the piperidine ring, which was nearly perpendicular to the membrane surface in the 7 TM domains. Molecular dynamic simulations were applied to evaluate potential relationships between ligand conformation and fentanyl substitution.展开更多
The relationships between the structure of oxime compounds(R^(1)R^(2)C=NOH,R^(1)/R^(2)=alkyl groups) with different substituents and their corresponding flotation performances were studied. The analyses of density fun...The relationships between the structure of oxime compounds(R^(1)R^(2)C=NOH,R^(1)/R^(2)=alkyl groups) with different substituents and their corresponding flotation performances were studied. The analyses of density functional theory(DFT) calculations illustrated that the introduced phenyl group at the R^(1) position could enhance the acidity,while the heptyl group could effectively increase the hydrophobicity and benefit van der Waals interactions. Meanwhile,the introduced amino group at the R^(2) position could provide cationic sites to interact with negatively charged surfaces of minerals, while the introduced hydroxyl group could provide additional action sites to form stable chelates with metal ions. Based on the structure-activity relationships, structural optimization was carried out to obtain three efficient collectors, which possessed superior flotation separation performances, proving the effectiveness of the structural modification to oxime compounds in this work.展开更多
The effects of eleven flavonoids on lipid peroxidation, protein degradation, deformability and osmotic fragility of human erythrocytes exposed in vitro to 10 mM H2O2 for 60 min at 37 oC have been studied. The followin...The effects of eleven flavonoids on lipid peroxidation, protein degradation, deformability and osmotic fragility of human erythrocytes exposed in vitro to 10 mM H2O2 for 60 min at 37 oC have been studied. The following flavonoids;quercetin, rutin and morin significantly protected eryt-hrocytes against lipid peroxidation caused by H2O2. This inhibition of lipid peroxidation could be explained by the presence of at least two hydroxyl groups in ring B of the flavonoid structure, regardless of their positions. However, the flavonoids;quercetin, 3,5,7-trihy- droxy-4'-methoxy flavone-7-rutinoside and 3- hydroxy flavone significantly protected eryt-hrocytes against protein degradation. This inhibition could also be explained by the presence of a hydroxyl group at C-3 in ring C of the flavonoid structure. Quercetin and 3,5,7-trihydroxy-4'- methoxy flvone-7-rutinoside significantly protected erythrocytes against loss of deformability and increased osmotic fragility, indicating that the loss of erythrocyte deformability and the increase in osmotic fragility of erythrocytes exposed to H2O2 are related to protein degradation rather than to lipid peroxidation. The other flavonoids (chrysin, 2-carboxy ethyl dihydroxy flavone, apigenin, cirsimaritin, α-naphto flavone and flavanone) failed to protect erythrocytes against the observed oxidative damages. The results demonstrate the importance of the chemical groups substituted on the basic skeleton of the flavonoids in dictating the type of antioxidant activity, and also demonstrate the hemorheological potentials of flavonoids that have particular protein-antioxidant activities.展开更多
In this study, solutions of hydrazine and its derivatives were irradiated using a pulsed electron beam to determine the half-reaction time of radiolysis. 3 D structures of the hydrazine derivatives were optimized, and...In this study, solutions of hydrazine and its derivatives were irradiated using a pulsed electron beam to determine the half-reaction time of radiolysis. 3 D structures of the hydrazine derivatives were optimized, and their energies were calculated using density functional theory with the B3 LYP method and 6-311 +(3 d, 3 p) basis set.For the first time, the 3 D quantitative structure-activity relationship(QSAR) equation describing the relationship between the hydrazine derivative structures and rate of radiolysis has been established using SPSS software.Pearson correlation analysis revealed a close correlation between the total energies of the molecules and half-reaction times. In the QSAR equation, Y =-7583.464 +54.687 X_1+94333.586 X_2,Y,X_1,and X_2 are the half-reaction time, total energy of the molecule, and orbital transition energy, respectively. The significance levels of the regression coefficients were 0.006 and 0.031, i.e., both less than 0.05. Thus, this model fully explains the relationship between hydrazine derivatives and β radiolysis stability.The results show that the total energy of the molecule and orbital transition energy are the main factors that influence the β radiolysis stability of these hydrazine derivatives.展开更多
The structural complexity of lithium-bearing clay minerals and limitations of conventional characterization methods impede efficient lithium extraction from montmorillonite-type ores.This study employs density functio...The structural complexity of lithium-bearing clay minerals and limitations of conventional characterization methods impede efficient lithium extraction from montmorillonite-type ores.This study employs density functional theory to elucidate structure-activity relationships governing lithium occurrence in montmorillonite,with particular emphasis on octahedral locking mechanisms and interfacial reaction barriers.Systematic calculations reveal four potential lithium occurrence sites:Al-O octahedra,Si-O tetrahedral lattices,interlayer sites and Li substituted H site.Lithium demonstrates optimal stability within Mg-Al-O octahedral lattices,exhibiting the lowest interaction energy(−672.982 kJ/mol)and substantial Mulliken charge transfer(2.35 e),confirming this configuration as the primary hosting environment.Density of states analysis uncovers critical electronic structure features:the 1s orbital of lithium remains energetically isolated from the Fermi level,explaining its chemical inertness and resistance to direct leaching.Conversely,the reactive 2p orbital of oxygen near the Fermi level facilitate surface interactions with flotation reagents.These electronic signatures imply the feasibility of flotation recovery alongside hydrometallurgical approaches.The octahedral locking mechanism originates from Li-induced dynamic symmetry reconstruction.This process achieves energy minimization through bond-angle regularization,while the notable contraction of Al-O/Mg-O bonds enhances electrostatic coupling.These synergistic effects ultimately establish a structural-charge dual-locking mechanism.This study delivers atomic-level insights into lithium occurrence mechanisms,addressing critical gaps in clay-type lithium mineralogy and revealing structure-activity relationships that guide sustainable lithium recovery via interface regulation.展开更多
The physicochemical properties,structural characteristics,antioxidant,radioprotective and lipid-lowering activities,as well as the underlying structure-activity relationships of polysaccharides extracted from Nostoc f...The physicochemical properties,structural characteristics,antioxidant,radioprotective and lipid-lowering activities,as well as the underlying structure-activity relationships of polysaccharides extracted from Nostoc flagelliforme grown under normal(WL-EPS-1),salt stress(NaCl-EPS-1)and mixotrophic culture conditions(Glu-EPS-1)were studied.The results demonstrated that WL-EPS-1,NaCl-EPS-1 and Glu-EPS-1 were heteropolysaccharides comprising different proportions of monosaccharides and uronic acid,with different average molecular weights of 0.99×10^(3),1.09×10^(3)and 1.18×10^(3)kDa,respectively.Their intrinsic viscosity were significantly different,at 24.72,29.98,and 41.06 dL/g,respectively.The functional groups of polysaccharides were not greatly affected,but the chemical composition,triple-helix structure,chain length and surface morphology were significantly influenced by culture conditions.In vitro bioactivity assays showed that the antioxidant activity generally increased in the order of WL-EPS-1<NaCl-EPS-1<Glu-EPS-1,while NaCl-EPS-1 had the best radioprotective effect,and Glu-EPS-1 had the best lipid-lowering effect.In addition,the structure-activity relationship of the polysaccharides was analyzed by partial least squares,which revealed that the most important factors affecting the antioxidant,radioprotective and lipid-lowering activities of polysaccharides were viscosity and molecular weight.This study provides a strategy for obtaining high-bioactivity polysaccharides by appropriate regulation of culture conditions,as well as opening new directions for the molecular modification of polysaccharides.展开更多
Demethoxylation was kinetically and spectroscopically studied over three catalysts with different Ru^(0)/Ru^(δ+) ratios.In-situ spectroscopic tests demonstrated that the synergy between Ru^(0)and Ru^(δ+) was crucial...Demethoxylation was kinetically and spectroscopically studied over three catalysts with different Ru^(0)/Ru^(δ+) ratios.In-situ spectroscopic tests demonstrated that the synergy between Ru^(0)and Ru^(δ+) was crucial,and Ru^(0) was in charge of H_(2) activation and adsorption of aromatic ring while Ru^(δ+) adsorbed with O in methoxyl.A Langmuir-Hinshelwood kinetic model was proposed,and ratio of Ru^(0)/Ru^(δ+) was the key in deciding the rate-determining step(RDS):i)desorp-tion of toluene was RDS over catalyst with highRu^(0)ratio;ii)dissociation of H_(2) was RDS over Ru^(δ+) enriched catalyst;iii)demethoxylation was rate-determined by CO water-gas shift (WGS) when Ru^(0)/Ru^(δ+) approached~1.The best perfor-mance was obtained over Ru/NiAl_(2)O_(4)-200,which effectively enabled both C-O bond activation and rapid recovery of adsorption sites for aromatic rings.Finally,in-situ DRIFT studies on methoxy decomposition and CO-WGS unraveled that the electronic composition of Ru was more stable in Ru/NiAl_(2)O_(4)-200 which contributes to its excellence.展开更多
Main observation and conclusion Methicillin-resistant Staphylococcus aureus(MRSA)has become a major threat on public health because of the increase of clinically isolated strains that exhibit resistance to many antibi...Main observation and conclusion Methicillin-resistant Staphylococcus aureus(MRSA)has become a major threat on public health because of the increase of clinically isolated strains that exhibit resistance to many antibiotics.Therefore,development of new antibiotics for the treatment of MRSA in-fection is a sustained challenge.We have previously identified a ring-opened bengamide analogue L472-2 that displays moderate ac-tivity against the growth of S.aureus.In our previous work,we started from L472-2 and identified a class of analogues containing al-kynyl groups which have the potential to activate SaCIpP activity but moderate antibacterial activity.Herein,we focused on the anti-bacterial activity of L472-2,and a novel series of ring-opened bengamide analogues were synthesized and their activities were evalu-ated against MRSA.By conducting a compact analysis of the structure-activity relationships(SAR)of these analogues,we found that an adamantane ethanol ester bengamide 2j showed excellent antibacterial activity towards six S.aureus strains,including MRSA,while it does not activate CIpP.Therefore,these bengamide analogues represent a new class of candidates that suppress MRSA via-bility..展开更多
NH_(3) in ambient air directly leads to an increase in the aerosol content in the air. These substances lead to the formation of haze to various environmental problems after atmospheric circulation and diffusion. Cont...NH_(3) in ambient air directly leads to an increase in the aerosol content in the air. These substances lead to the formation of haze to various environmental problems after atmospheric circulation and diffusion. Controlling NH_(3) emissions caused by ammonia escaping from mobile and industrial sources can effectively reduce the NH_(3) content in ambient air. Among the various NH_(3) removal methods, the selective catalytic oxygen method (NH_(3)-SCO) is committed to oxidizing NH_(3) to environmentally harmless H_(2)O and N_(2);therefore, it is the most valuable and ideal ammonia removal method. In this review, the characteristics of loaded and core-shell catalysts in NH_(3)-SCO have been reviewed in the context of catalyst structure-activity relationships, and the H_(2)O resistance and SO2 resistance of the catalysts are discussed in the context of practical application conditions. Then the effects of the valence state of the active center, oxygen species on the catalyst surface, dispersion of the active center and acidic sites on the catalyst performance are discussed comprehensively. Finally, the shortcomings of the existing catalysts are summarized and the catalyst development is discussed based on the existing studies.展开更多
Developing bimetallic catalysts is an effective strategy for enhancing the activity and selectivity of electrochemical CO_(2) reduction reactions,where understanding the structure-activity relationship is essential fo...Developing bimetallic catalysts is an effective strategy for enhancing the activity and selectivity of electrochemical CO_(2) reduction reactions,where understanding the structure-activity relationship is essential for catalyst design.Herein,we prepared two Cu-Ag bimetallic catalysts with Ag nanoparticles attached to the top or the bottom of Cu nanowires.When tested in a flow cell,the Cu-Ag catalyst with Ag nanoparticles on the bottom achieved a faradaic efficiency of 54%for ethylene production,much higher than the catalyst with Ag nanoparticles on the top.The catalysts were further studied in the H-cell and zero-gap MEA cell.It was found that placing the two metals in the intensified reaction zone is crucial to triggering the tandem reaction of bimetallic catalysts.Our work elucidates the structure-activity relationship of bimetallic catalysts for CO_(2) reduction and demonstrates the importance of considering both catalyst structures and cell characteristics to achieve high activity and selectivity.展开更多
Background With the rapid growth of internet usage,adolescent cyberbullying has become a pressing issue.This study examines the longitudinal impact of leisure-time physical activity and peer relationships on cyberbull...Background With the rapid growth of internet usage,adolescent cyberbullying has become a pressing issue.This study examines the longitudinal impact of leisure-time physical activity and peer relationships on cyberbullying over a one-year period,drawing on the Stage-Environment Fit Theory and the Interpersonal Relationship Theory.Methods A three-wave longitudinal study was conducted over one year,involving 896 middle school students from five schools in Sichuan,Jiangsu,and Guangdong,China,selected to ensure regional diversity.Participants were recruited using stratified random sampling,and data were collected at four-month intervals.Leisure-time physical activity,peer relationships,and cyberbullying behaviors were assessed using validated scales.Data were analyzed using latent growth modeling(LGM)and structural equation modeling(SEM)to examine longitudinal effects and mediation relationships.Results(1)Leisure-time physical activity,peer relationships,and cyberbullying behaviors remained relatively stable over time.(2)Both leisure-time physical activity and peer relationships significantly reduced future cyberbullying incidents,with physical activity also enhancing subsequent peer relationships.(3)Peer relationships partially mediated the effect of leisure-time physical activity on cyberbullying,indicating that improved peer interactions contributed to a reduction in cyberbullying behaviors.Conclusion This study found that leisure-time sports activities and peer relationships are important factors affecting cyberbullying,and peer relationships play a partial mediating role in it.The results provide empirical support for understanding the formation mechanism and influencing factors of cyberbullying.展开更多
The interaction between supply chain relationships and corporate finance has become a focal issue in academic and practical circles,especially under the dual drivers of globalization and marketization.This paper syste...The interaction between supply chain relationships and corporate finance has become a focal issue in academic and practical circles,especially under the dual drivers of globalization and marketization.This paper systematically reviews existing research on this topic,covering theoretical foundations from perspectives such as agency theory,stakeholder theory,and co-opetition game theory,which explain the nature of customer-supplier relationships.It also combs through empirical studies from four core angles:competition-cooperation,signal transmission,spillover effects,and information transfer,summarizing findings on how supply chain relationships impact corporate investment,financing,operations,and performance,as well as existing controversies.The aim is to clarify the research context,identify theoretical and empirical gaps,and provide theoretical support and direction for deepening future research on supply chain and corporate finance.展开更多
Within the prefrontal-cingulate cortex,abnormalities in coupling between neuronal networks can disturb the emotion-cognition interactions,contributing to the development of mental disorders such as depression.Despite ...Within the prefrontal-cingulate cortex,abnormalities in coupling between neuronal networks can disturb the emotion-cognition interactions,contributing to the development of mental disorders such as depression.Despite this understanding,the neural circuit mechanisms underlying this phenomenon remain elusive.In this study,we present a biophysical computational model encompassing three crucial regions,including the dorsolateral prefrontal cortex,subgenual anterior cingulate cortex,and ventromedial prefrontal cortex.The objective is to investigate the role of coupling relationships within the prefrontal-cingulate cortex networks in balancing emotions and cognitive processes.The numerical results confirm that coupled weights play a crucial role in the balance of emotional cognitive networks.Furthermore,our model predicts the pathogenic mechanism of depression resulting from abnormalities in the subgenual cortex,and network functionality was restored through intervention in the dorsolateral prefrontal cortex.This study utilizes computational modeling techniques to provide an insight explanation for the diagnosis and treatment of depression.展开更多
基金the National Natural Science Foundation of China(No.32272575)National College Student Innovation and Entrepreneurship Training Program(No.202210459164)for financial support.
文摘Methicillin-resistant Staphylococcus aureus (MRSA), the most common pathogen in hospital and community environments, can cause serious and even fatal infections. The antibiotics currently used for clinical treatment of MRSA have developed resistance, and there is an urgent need to develop new antimicrobials to treat infections caused by MRSA strains. Quinoline analogues play an important role in the development of antimicrobials. Herein, we discussed the current development of antibacterial activities of quinoline analogues, mainly for anti-MRSA activity, and their structure-activity relationships (SARs) from the perspective of using the quinoline nucleus to search for novel potential anti-MRSA candidates. Additionally, the mechanisms of some representative quinoline analogues against MRSA were clarified. Altogether, this review could provide further insights for the rational development of quinoline-based antibacterial drugs, especially against MRSA.
文摘In searching for effective anticonvulsant agents,fourteen 6-aryl-4.5-di- hydro-3(2H)pyridazinones.fifteen 6-aryl-3(2H)pyridazinones,and seventeen 3-GABA derivatives of 6-aryIpyridazines have been synthesized,and evaluated in mice for the ability to antagonize maximal electroshock seizure(MES).The ED_(50) values showed that 6-(2′,4′- dichlorophenyt)-3(2H)pyridazinone was the most potent anticonvulsant among these corn- pounds(ED_(50)=10.15 mg/kg).The structure-activity relationships of the aryl pyridazinones were studied.The result showed that:(1)the higher the value of the hydrophobic parameter л of the substituent on the phenyl ring.the more potent the anticonvulsant activity of the corn- pound.and(2)only the compounds with an electron withdrawing substituent on the phenyl ring exhibited appreciable anticonvulsant activity.
基金Supported by the National Natural Science Foundation of China(31060045,31260091)~~
文摘Taking the six common anthocyanidins in nature, i.e. cyanidin, delphinidin, malvidin, pelargonidin, peonidin and petunidin, as examples, this paper summarized the main achievements about the structure-activity relationships of the coloration and stability of anthocyanidins. The coloration and stability of anthocyanidins are funda- mentally determined by the chemical and spatial structures of the anthocyanidins. The electron-deficient state, hydroxylation and methylation patterns, especially the ones on the B-ring, and coplanarity of the three rings of anthocyanidins are inde- pendently or synergetically, positively and/or negatively, influence the coloration and stability of the anthocyanidins. Thereinto, the in vivo colorations of anthocyanins are also related to the organ-selective and crystal- or anthocyanic vacuolar inclusion- related existence of the anthocyanidins. This review could provide a reference for the researches of the structure-optimizing and function-exploiting of anthocyanidins and also for the selection of the crops and cultivars containing specific anthocyani- din profiles.
基金financially supported by the National Natural Science Foundation of China(No.51873133)。
文摘Aerogels are special porous materials with low thermal conductivity,light weight,high energy absorption rate and large surface area,which have been applied in many fields.However,controlling the aerogel microstructure remains an academic challenge.Herein,by employing graphene oxide(GO)as the aerogel skeleton and utilizing poly(vinyl alcohol)(PVA)to regulate the ice crystal growth,we elucidate the relationships between the physicochemical properties of GO/PVA aerogel precursors and the nucleation and growth of ice crystals by using an ice-templating method.We demonstrate that due to the hydrogen bond formed between PVA and water molecules,resulting in the initial crystallization temperature being reduced from-12.60℃(GO/PVA-0.01)to-16.21℃(GO/PVA-0.1).Meanwhile,the strong hydrogen bond between PVA and GO limits the diffusion of water molecules,thereby inhibiting the growth of ice crystals,decreasing the pore size of the GO/PVA aerogel from 9.96 nm(GO/PVA-0.01)to 7.19 nm(GO/PVA-0.3),and thus the compressive strength of the aerogel increases from 0.045 MPa to 0.13MPa.Overall,the finding of this study can be extended to other aerogel precursors,and exhibit important scientific value and practical significance for the preparation of aerogel materials with highly controllable structures and performances.
基金Supported by the National Natural Science Foundation of China (20873096, 20621502)the Science and Technology Research Item of Hubei Provincial Department of Education (D20093103)
文摘The growth of Staphylococcus aureus under the action of six kinds of Schiff bases（A,B,C,D,E,F） was studied by means of microcalorimetry. Growth constant k and inhibition ratio I were calculated. Also,the antibacterial activity,the action characteristics and the structure-activity relationships of the compounds on S. aureus were analyzed. Results indicate that B,F show good antibacterial activity（IC50：293.6 mg · L-1 and 307.8 mg · L-1） ,D,E show moderate antibacterial activity（IC50：966.3 mg · L-1 and 1 126.7 mg · L-1） ,and A,C just show weak antibacterial activity（IC50 〉1 200 mg · L-1） . The I-c curves mainly present a straight line shape for B,D,E and F,but an inverse ＂S＂ shape for A and C. Structure-activity relationships analysis suggests that the species and position of the substituents determine the antibacterial activity of these Schiff bases,and the charge density distribution is one of the most important influencing factors.
基金the National Natural Science Foundation of China (No.U1502223)Hunan Provincial Key Research and Development Project (Grant No.2021WK2005 to X.Deng)+1 种基金Natural Science Foundation of Hunan Province (Grant No.2021JJ30894 to X.Deng)the open fund of State Key Laboratory of Phytochemistry and Plant Resource in West China (Grant No.P2020-KF03).
文摘11β-Hydroxysteroid dehydrogenase 1(11β-HSD1)represents a promising drug target for metabolic syndrome,includ-ing obesity and type 2 diabetes.Our initial screen of a collection of natural products from Danshen led to the identi-fication of tanshinones as the potent and selective 11β-HSD1 inhibitors.To improve the druggability and explore the structure-activity relationships(SARs),more than 40 derivatives have been designed and synthesized using tanshinone IIA and cryptotanshinone as the starting materials.More than 10 derivatives exhibited potent in vitro 11β-HSD1 inhibitory activity and good selectivity over 11β-HSD2 across human and mouse species.Based on the biological results,SARs were further discussed,which was also partially rationalized by a molecular docking model of 1 bound to the 11β-HSD1.Remarkably,compounds 1,17 and 30 significantly inhibited 11β-HSD1 in 3T3-L1 adipocyte and in livers of ob/ob mice,which merits further investigations as anti-diabetic agents.This study not only provides a series of novel selective 11β-HSD1 inhibitors with promising therapeutic potentials in metabolic syndromes,but also expands the boundaries of the chemical and biological spaces of tanshinones.
基金Project(No.31071501)supported by the National Natural Science Foundation of China
文摘Fatty acids and derivatives(FADs)are resources for natural antimicrobials.In order to screen for additional potent antimicrobial agents,the antimicrobial activities of FADs against Staphylococcus aureus were examined using a microplate assay.Monoglycerides of fatty acids were the most potent class of fatty acids,among which monotridecanoin possessed the most potent antimicrobial activity.The conventional quantitative structure-activity relationship(QSAR)and comparative molecular field analysis(CoMFA)were performed to establish two statistically reliable models(conventional QSAR:R2=0.942,Q 2 LOO=0.910;CoMFA:R 2=0.979,Q 2=0.588,respectively).Improved forecasting can be achieved by the combination of these two models that provide a good insight into the structureactivity relationships of the FADs and that may be useful to design new FADs as antimicrobial agents.
基金supported by the National Natural Science Foundation of China(Molecular design,catalysis and synthesis methods of novel fentanyl analogs active compounds)No.20872095
文摘Fentanyl is a potent and widely used clinical narcotic analgesic, as well as a highly selective IJ-opioid agonist. The present study established a homologous model of the human μ-opioid receptor; an intercomparison of three types of μ-opioid receptor protein sequence homologous rates was made. The secondary receptor structure was predicted, the model reliability was assessed and verified using the Ramachandran plot and ProTab analysis. The predictive ability of the CoMFA model was further validated using an external test set. Using the Surflex-Dock program, a series of fentanyl analog molecules were docked to the receptor, the calculation results from Biopolymer/SitelD showed that the receptor had a deep binding area situated in the extracellular side of the transmembrane domains （TM） among TM3, TM5, TM6, and TMT. Results suggested that there might be 5 active areas in the receptor. The important residues were Asp147, Tyr148, and Tyr149 in TM3, Trp293, and His297 in TM6, and Trp318, His319, Ile322, and Tyr326 in TM7, which were located at the 5 active areas. The best fentanyl docking orientation position was the piperidine ring, which was nearly perpendicular to the membrane surface in the 7 TM domains. Molecular dynamic simulations were applied to evaluate potential relationships between ligand conformation and fentanyl substitution.
基金the support of the National Natural Science Foundation of China(Nos.51774329 and 51904337)the High Performance Computing Center of Central South University,China。
文摘The relationships between the structure of oxime compounds(R^(1)R^(2)C=NOH,R^(1)/R^(2)=alkyl groups) with different substituents and their corresponding flotation performances were studied. The analyses of density functional theory(DFT) calculations illustrated that the introduced phenyl group at the R^(1) position could enhance the acidity,while the heptyl group could effectively increase the hydrophobicity and benefit van der Waals interactions. Meanwhile,the introduced amino group at the R^(2) position could provide cationic sites to interact with negatively charged surfaces of minerals, while the introduced hydroxyl group could provide additional action sites to form stable chelates with metal ions. Based on the structure-activity relationships, structural optimization was carried out to obtain three efficient collectors, which possessed superior flotation separation performances, proving the effectiveness of the structural modification to oxime compounds in this work.
文摘The effects of eleven flavonoids on lipid peroxidation, protein degradation, deformability and osmotic fragility of human erythrocytes exposed in vitro to 10 mM H2O2 for 60 min at 37 oC have been studied. The following flavonoids;quercetin, rutin and morin significantly protected eryt-hrocytes against lipid peroxidation caused by H2O2. This inhibition of lipid peroxidation could be explained by the presence of at least two hydroxyl groups in ring B of the flavonoid structure, regardless of their positions. However, the flavonoids;quercetin, 3,5,7-trihy- droxy-4'-methoxy flavone-7-rutinoside and 3- hydroxy flavone significantly protected eryt-hrocytes against protein degradation. This inhibition could also be explained by the presence of a hydroxyl group at C-3 in ring C of the flavonoid structure. Quercetin and 3,5,7-trihydroxy-4'- methoxy flvone-7-rutinoside significantly protected erythrocytes against loss of deformability and increased osmotic fragility, indicating that the loss of erythrocyte deformability and the increase in osmotic fragility of erythrocytes exposed to H2O2 are related to protein degradation rather than to lipid peroxidation. The other flavonoids (chrysin, 2-carboxy ethyl dihydroxy flavone, apigenin, cirsimaritin, α-naphto flavone and flavanone) failed to protect erythrocytes against the observed oxidative damages. The results demonstrate the importance of the chemical groups substituted on the basic skeleton of the flavonoids in dictating the type of antioxidant activity, and also demonstrate the hemorheological potentials of flavonoids that have particular protein-antioxidant activities.
文摘In this study, solutions of hydrazine and its derivatives were irradiated using a pulsed electron beam to determine the half-reaction time of radiolysis. 3 D structures of the hydrazine derivatives were optimized, and their energies were calculated using density functional theory with the B3 LYP method and 6-311 +(3 d, 3 p) basis set.For the first time, the 3 D quantitative structure-activity relationship(QSAR) equation describing the relationship between the hydrazine derivative structures and rate of radiolysis has been established using SPSS software.Pearson correlation analysis revealed a close correlation between the total energies of the molecules and half-reaction times. In the QSAR equation, Y =-7583.464 +54.687 X_1+94333.586 X_2,Y,X_1,and X_2 are the half-reaction time, total energy of the molecule, and orbital transition energy, respectively. The significance levels of the regression coefficients were 0.006 and 0.031, i.e., both less than 0.05. Thus, this model fully explains the relationship between hydrazine derivatives and β radiolysis stability.The results show that the total energy of the molecule and orbital transition energy are the main factors that influence the β radiolysis stability of these hydrazine derivatives.
基金support by Yunnan Provincial Science and Technology Department(grant No.202301AS070033)is sincerely appreciated。
文摘The structural complexity of lithium-bearing clay minerals and limitations of conventional characterization methods impede efficient lithium extraction from montmorillonite-type ores.This study employs density functional theory to elucidate structure-activity relationships governing lithium occurrence in montmorillonite,with particular emphasis on octahedral locking mechanisms and interfacial reaction barriers.Systematic calculations reveal four potential lithium occurrence sites:Al-O octahedra,Si-O tetrahedral lattices,interlayer sites and Li substituted H site.Lithium demonstrates optimal stability within Mg-Al-O octahedral lattices,exhibiting the lowest interaction energy(−672.982 kJ/mol)and substantial Mulliken charge transfer(2.35 e),confirming this configuration as the primary hosting environment.Density of states analysis uncovers critical electronic structure features:the 1s orbital of lithium remains energetically isolated from the Fermi level,explaining its chemical inertness and resistance to direct leaching.Conversely,the reactive 2p orbital of oxygen near the Fermi level facilitate surface interactions with flotation reagents.These electronic signatures imply the feasibility of flotation recovery alongside hydrometallurgical approaches.The octahedral locking mechanism originates from Li-induced dynamic symmetry reconstruction.This process achieves energy minimization through bond-angle regularization,while the notable contraction of Al-O/Mg-O bonds enhances electrostatic coupling.These synergistic effects ultimately establish a structural-charge dual-locking mechanism.This study delivers atomic-level insights into lithium occurrence mechanisms,addressing critical gaps in clay-type lithium mineralogy and revealing structure-activity relationships that guide sustainable lithium recovery via interface regulation.
基金support from the National Natural Science Foundation of China(32172191)the Tianjin Research Innovation Project for Postgraduate Students(2021YJSB211).
文摘The physicochemical properties,structural characteristics,antioxidant,radioprotective and lipid-lowering activities,as well as the underlying structure-activity relationships of polysaccharides extracted from Nostoc flagelliforme grown under normal(WL-EPS-1),salt stress(NaCl-EPS-1)and mixotrophic culture conditions(Glu-EPS-1)were studied.The results demonstrated that WL-EPS-1,NaCl-EPS-1 and Glu-EPS-1 were heteropolysaccharides comprising different proportions of monosaccharides and uronic acid,with different average molecular weights of 0.99×10^(3),1.09×10^(3)and 1.18×10^(3)kDa,respectively.Their intrinsic viscosity were significantly different,at 24.72,29.98,and 41.06 dL/g,respectively.The functional groups of polysaccharides were not greatly affected,but the chemical composition,triple-helix structure,chain length and surface morphology were significantly influenced by culture conditions.In vitro bioactivity assays showed that the antioxidant activity generally increased in the order of WL-EPS-1<NaCl-EPS-1<Glu-EPS-1,while NaCl-EPS-1 had the best radioprotective effect,and Glu-EPS-1 had the best lipid-lowering effect.In addition,the structure-activity relationship of the polysaccharides was analyzed by partial least squares,which revealed that the most important factors affecting the antioxidant,radioprotective and lipid-lowering activities of polysaccharides were viscosity and molecular weight.This study provides a strategy for obtaining high-bioactivity polysaccharides by appropriate regulation of culture conditions,as well as opening new directions for the molecular modification of polysaccharides.
基金supported financially by the National Key Research and Development Program of China(No.2022YFA1504900)the NSFC of China(No.22072041,21832002)the Science and Technology Commission of Shanghai Municipality(10dz2220500).
文摘Demethoxylation was kinetically and spectroscopically studied over three catalysts with different Ru^(0)/Ru^(δ+) ratios.In-situ spectroscopic tests demonstrated that the synergy between Ru^(0)and Ru^(δ+) was crucial,and Ru^(0) was in charge of H_(2) activation and adsorption of aromatic ring while Ru^(δ+) adsorbed with O in methoxyl.A Langmuir-Hinshelwood kinetic model was proposed,and ratio of Ru^(0)/Ru^(δ+) was the key in deciding the rate-determining step(RDS):i)desorp-tion of toluene was RDS over catalyst with highRu^(0)ratio;ii)dissociation of H_(2) was RDS over Ru^(δ+) enriched catalyst;iii)demethoxylation was rate-determined by CO water-gas shift (WGS) when Ru^(0)/Ru^(δ+) approached~1.The best perfor-mance was obtained over Ru/NiAl_(2)O_(4)-200,which effectively enabled both C-O bond activation and rapid recovery of adsorption sites for aromatic rings.Finally,in-situ DRIFT studies on methoxy decomposition and CO-WGS unraveled that the electronic composition of Ru was more stable in Ru/NiAl_(2)O_(4)-200 which contributes to its excellence.
基金the Science and Technology Commission of Shanghai Municipality(No.16ZR1407000)the National Natural Science Foundation of China(Nos.81861138046 and 21725801).
文摘Main observation and conclusion Methicillin-resistant Staphylococcus aureus(MRSA)has become a major threat on public health because of the increase of clinically isolated strains that exhibit resistance to many antibiotics.Therefore,development of new antibiotics for the treatment of MRSA in-fection is a sustained challenge.We have previously identified a ring-opened bengamide analogue L472-2 that displays moderate ac-tivity against the growth of S.aureus.In our previous work,we started from L472-2 and identified a class of analogues containing al-kynyl groups which have the potential to activate SaCIpP activity but moderate antibacterial activity.Herein,we focused on the anti-bacterial activity of L472-2,and a novel series of ring-opened bengamide analogues were synthesized and their activities were evalu-ated against MRSA.By conducting a compact analysis of the structure-activity relationships(SAR)of these analogues,we found that an adamantane ethanol ester bengamide 2j showed excellent antibacterial activity towards six S.aureus strains,including MRSA,while it does not activate CIpP.Therefore,these bengamide analogues represent a new class of candidates that suppress MRSA via-bility..
基金the National Natural Science Foundation of China(No.52000093)Yunnan Fundamental Research Projects(No.202101BE070001-001)National Engineering Laboratory for Mobile Source Emission Control Technology(No.NELMS2019B03).
文摘NH_(3) in ambient air directly leads to an increase in the aerosol content in the air. These substances lead to the formation of haze to various environmental problems after atmospheric circulation and diffusion. Controlling NH_(3) emissions caused by ammonia escaping from mobile and industrial sources can effectively reduce the NH_(3) content in ambient air. Among the various NH_(3) removal methods, the selective catalytic oxygen method (NH_(3)-SCO) is committed to oxidizing NH_(3) to environmentally harmless H_(2)O and N_(2);therefore, it is the most valuable and ideal ammonia removal method. In this review, the characteristics of loaded and core-shell catalysts in NH_(3)-SCO have been reviewed in the context of catalyst structure-activity relationships, and the H_(2)O resistance and SO2 resistance of the catalysts are discussed in the context of practical application conditions. Then the effects of the valence state of the active center, oxygen species on the catalyst surface, dispersion of the active center and acidic sites on the catalyst performance are discussed comprehensively. Finally, the shortcomings of the existing catalysts are summarized and the catalyst development is discussed based on the existing studies.
基金the funding support from the National Key Research and Development Program of China(2019YFE0123400)the Tianjin Distinguished Young Scholars Fund(20JCJQJC00260)+4 种基金the Major Science and Technology Project of Anhui Province(202203f07020007)the Anhui Conch Group Co.,Ltdthe“111”Project(B16027)the funding support from the Natural Science Foundation of China(22209081)the fellowship of China Postdoctoral Science Foundation(2021M690082)。
文摘Developing bimetallic catalysts is an effective strategy for enhancing the activity and selectivity of electrochemical CO_(2) reduction reactions,where understanding the structure-activity relationship is essential for catalyst design.Herein,we prepared two Cu-Ag bimetallic catalysts with Ag nanoparticles attached to the top or the bottom of Cu nanowires.When tested in a flow cell,the Cu-Ag catalyst with Ag nanoparticles on the bottom achieved a faradaic efficiency of 54%for ethylene production,much higher than the catalyst with Ag nanoparticles on the top.The catalysts were further studied in the H-cell and zero-gap MEA cell.It was found that placing the two metals in the intensified reaction zone is crucial to triggering the tandem reaction of bimetallic catalysts.Our work elucidates the structure-activity relationship of bimetallic catalysts for CO_(2) reduction and demonstrates the importance of considering both catalyst structures and cell characteristics to achieve high activity and selectivity.
基金funded by the following projects:National Social Science Fund Project“The Empowerment Mechanism of Physical Exercise on Emotional Regulation in Adolescents”(23BTY116)Leshan Normal University 2024 Research Cultivation Project:“Research on the Trajectory Effect of Family Cumulative Risk and Home-based Activity of Adolescents”(KYPY2025-0014)+1 种基金Key Humanities and Social Sciences Cultivation Project of Leshan Normal University:“Research on the Sequence Difference of Knowledge and Behavior of Physical Activity among Adolescents and the Compensation Mechanism”and Sichuan Province College Students’Sports Association Annual Project“The Trajectory Effect of Family Cumulative Risk and Adolescents’Home Physical Activity”(23CDTXQ004).
文摘Background With the rapid growth of internet usage,adolescent cyberbullying has become a pressing issue.This study examines the longitudinal impact of leisure-time physical activity and peer relationships on cyberbullying over a one-year period,drawing on the Stage-Environment Fit Theory and the Interpersonal Relationship Theory.Methods A three-wave longitudinal study was conducted over one year,involving 896 middle school students from five schools in Sichuan,Jiangsu,and Guangdong,China,selected to ensure regional diversity.Participants were recruited using stratified random sampling,and data were collected at four-month intervals.Leisure-time physical activity,peer relationships,and cyberbullying behaviors were assessed using validated scales.Data were analyzed using latent growth modeling(LGM)and structural equation modeling(SEM)to examine longitudinal effects and mediation relationships.Results(1)Leisure-time physical activity,peer relationships,and cyberbullying behaviors remained relatively stable over time.(2)Both leisure-time physical activity and peer relationships significantly reduced future cyberbullying incidents,with physical activity also enhancing subsequent peer relationships.(3)Peer relationships partially mediated the effect of leisure-time physical activity on cyberbullying,indicating that improved peer interactions contributed to a reduction in cyberbullying behaviors.Conclusion This study found that leisure-time sports activities and peer relationships are important factors affecting cyberbullying,and peer relationships play a partial mediating role in it.The results provide empirical support for understanding the formation mechanism and influencing factors of cyberbullying.
文摘The interaction between supply chain relationships and corporate finance has become a focal issue in academic and practical circles,especially under the dual drivers of globalization and marketization.This paper systematically reviews existing research on this topic,covering theoretical foundations from perspectives such as agency theory,stakeholder theory,and co-opetition game theory,which explain the nature of customer-supplier relationships.It also combs through empirical studies from four core angles:competition-cooperation,signal transmission,spillover effects,and information transfer,summarizing findings on how supply chain relationships impact corporate investment,financing,operations,and performance,as well as existing controversies.The aim is to clarify the research context,identify theoretical and empirical gaps,and provide theoretical support and direction for deepening future research on supply chain and corporate finance.
基金supported by the Major Research Instrument Development Project of the National Natural Science Foundation of China(82327810)the Foundation of the President of Hebei University(XZJJ202202)the Hebei Province“333 talent project”(A202101058).
文摘Within the prefrontal-cingulate cortex,abnormalities in coupling between neuronal networks can disturb the emotion-cognition interactions,contributing to the development of mental disorders such as depression.Despite this understanding,the neural circuit mechanisms underlying this phenomenon remain elusive.In this study,we present a biophysical computational model encompassing three crucial regions,including the dorsolateral prefrontal cortex,subgenual anterior cingulate cortex,and ventromedial prefrontal cortex.The objective is to investigate the role of coupling relationships within the prefrontal-cingulate cortex networks in balancing emotions and cognitive processes.The numerical results confirm that coupled weights play a crucial role in the balance of emotional cognitive networks.Furthermore,our model predicts the pathogenic mechanism of depression resulting from abnormalities in the subgenual cortex,and network functionality was restored through intervention in the dorsolateral prefrontal cortex.This study utilizes computational modeling techniques to provide an insight explanation for the diagnosis and treatment of depression.
