Microcalorimetric investigation of the effect of berberine alkaloids from Coptis chinensis Franch on Staphylococcus aureus growth

The inhibitory effects of three berberine alkaloids (BAs) from rhizome of Coptis chinensis Franch, a traditional Chinese medicinal (TCM) herb, on Staphylococcus aureus growth were investigated by mi- crocalorimetry. The power–time curves of S. aureus with and without BAs were acquired; meanwhile the extent and duration of inhibitory effects on the metabolism were evaluated by studying the growth rate constant (k), half inhibitory ratio (IC50), maximum heat-output power (Pmax), peak time of maximum heat-output power (tp) and total heat production (Qt). The value of k of S. aureus in the presence of the three BAs decreased with the increasing concentrations of BAs. Moreover, Pmax was reduced and the value of tp increased with increasing concentrations of the three drugs. The inhibitory activity varied with different drugs. The values of IC50 of the three BAs are respectively, 101.4 μg/mL for berberine, 241.0 μg/mL for palmatine and 792.3 μg/mL for jateorrhizine. The sequence of antimicrobial activity of the three BAs is: berberine > palmatine > jateorrhizine. It is suggested that the functional group me- thylenedioxy or methoxyl at C2 on the phenyl ring could possibly improve antimicrobial activity more strongly than hydroxyl at C2 on the phenyl ring.     

Synthesis, characterization and antibacterial properties of multifunctional hindered amine light stabilizers

A series of novel hindered amine light stabilizers containing an N-halamine moiety were designed and synthesized. Their structures were characterized by FT-IR, 1H NMR, and MS. The compounds were tested for antibacterial activity against Candida albicans, Staphylococcus aureus, and Escherichia coll. At a concentration of 0.5 mmol/L, these compounds all exhibited satisfactory antibacterial activity against all the three types of bacteria.     

Action of the Selenomorpholine Compounds on the Bacterium Growth by Microcalorimetry

The action of β-(N-selenomorpholine) ethyl phenyl ketone hydrochloride and 4-(N-selenomorpholine)-2-butanone hydro-chloride on Escherichia coli and Staphylococcus aureus was studied by microcalorimetry,Differences in their capacities to affect the metabolism of this bacterium were observed.The kinetics shows that the selenomorpholine compounds had action on the metabolism process of Escherichia coli and Staphylococcus aureus.The rate constant (k) of the studied bacterium in the presence of the drugs are concentration-dependant.The growth rate constants decrease with an increase in the mass of the selenomorpholine compounds ,but their relationship is different.As deduced from the rate constant(k) of the studied bacterium(in log phase )and the half inhibitory concentration (IC50),the experimental results reveal that the studied selenomorpholine compounds all have good antibiotic activity and better antibacterial activity on Staphylcoccus aureus than on Escherichia coli.     

Comparison of Catalytical and Biological Activities for Substituted Polyoxotungstates Containing Ti and CpTi

The effect of the functionallizagtion of POMs on their properties was examined by the comparison between both titanium and its corresponding cyclopentadienyl subsituted polyoxocomplexes.The polarographic half-wave potential of the complexes indicated that the effect of the functionallization of POMs increased the oxidizing ability of the polyoxoanions.The inhibitory effects of the CpTi polyoxocomplexes on tumor cells are higher than those of the corresponding titanium polyoxocomplexes,and the toxicity of the former is lower than that of the latter,The oxygenation reactions of cyclohexene,styrene,trans-stilbene and maleic acid with PhIO or hydrogen peroxide(30% aqueous solution) catalyzed respectively by Ti and CpTi polyoxocomplexes were compared.     

Microcalorimetric Study of the Action of Yb^3＋ ion on the Growth of Staphylococcus aureus

A microcalorimetric method was used to evaluate the action of Yb^3 ions onthe growth metabolism of Staphylococcus aureus.The power-time curves of the growth metabolism of Staphylo.coccus aureus and the action of Yb^3 ions were obtained by us-ing stopped-flow method at 37 ℃. For evaluation of the action,the growth rate constants ( k1 and k2) for the log phase 1, log phase 2, and the total heat effect (Qtotal) for Staphylococcus aureus were determined. The results show that Yb^3 ions at low concentrations have the stimnlatory effect on Staphylococcus au-reus and that Yb^3 ions at higher concentration could inhibit its growth.     

Effect of ZSM-5 zeolite morphology on the catalytic performance of the alkylation of toluene with methanol

A series of ZSM-5 zeolites, with the morphologies of sphere, sphere with cubic particles on the surface, and cubic particles, were synthesized by hydrothermal method using n-butylamine as the template, assisted by the addition of NaCl and crystal seed. X-ray diffraction(XRD),scanning electron microscope(SEM), X-ray fluorescence(XRF) and temperature-programmed desorption of ammonia(NH3-TPD) were used to characterize these samples. The samples were tested with toluene methylation reaction. The modified sample composed of spherical particles with 3 μm crystal particles on the surface had a para-xylene selectivity of 95% and maintained 79% of the initial conversion after running the reaction for 50 h. This modified sample showed the best stability among the tested three modified samples.     

Effect of ZSM-5 zeolite morphology on the catalytic performance of the alkylation of toluene with methanol

A series of ZSM-5 zeolites, with the morphologies of sphere, sphere with cubic particles on the surface, and cubic particles, were synthesized by hydrothermal method using n-butylamine as the template, assisted by the addition of NaCl and crystal seed. X-ray diffraction(XRD),scanning electron microscope(SEM), X-ray fluorescence(XRF) and temperature-programmed desorption of ammonia(NH3-TPD) were used to characterize these samples. The samples were tested with toluene methylation reaction. The modified sample composed of spherical particles with 3 μm crystal particles on the surface had a para-xylene selectivity of 95% and maintained 79% of the initial conversion after running the reaction for 50 h. This modified sample showed the best stability among the tested three modified samples.     

Crystal Structures,Thermal Behaviors and Biological Activities of Acylhydrazone Compounds Containing Pyrazine Rings and Halogen Atoms

Three new kinds of acylhydrazone compounds(C_(12)H_(10)FN_5O·H_2O,1;C_(12)H_(10)Cl N_5O·2CH_3COOH,2;C_(12)H_(10)Br N_5O,3)were synthesized by the reaction of 2-amino-3-pyrazinecarbohydrazide(C_5H_7N_5O)with halogenated benzaldehyde(C_7H_5OX,X=F,Cl,Br).The structures of the three compounds were characterized by elemental analysis,~1H NMR,IR and X-ray diffraction.X-ray single-crystal diffraction presents that the three compounds all belong to triclinic system,P1 space group.Thermal gravity analyses show that three compounds have excellent thermal stabilities and all the thermal decomposition temperature of maximum weight loss was around 300°C.The interactions of the compounds with CT-DNA were investigated by UV-Vis spectrum,fluorescence spectrum and viscosity measurement.All the results suggest that three compounds could bind with CT-DNA through intercalation.The fluorescence spectrum was also used to study the interactions of three compounds with BSA.It was proved that all the compounds could quench the intrinsic fluorescence of BSA via a static quenching process.Compound 2 displays the strongest binding ability both in the reaction with CT-DNA or BSA.Antimicrobial test was carried on Escherichia coli,Staphylococcus aureus and Salmonella,and 2 is more effective against S.aureus.But in MTT assay,1 shows better cytotoxity activity against A549cells.     

Investigation of the Interaction between Isoflavonoids and Bovine Serum Albumin by Fluorescence Spectroscopy

The interactions of bovine serum albumin （BSA） with three structurally related isoflavonoids, genistein, puerarin and daidzein, were studied under physiological conditions by fluorescence spectroscopic technique. The quenching mechanism of these compounds with BSA was suggested as static quenching and the binding constants were determined at different temperatures based on the fluorescence quenching results. The transfer efficiency of energy and distance between the acceptor and BSA were investigated on the basis of the mechanism of the Forster energy transference. According to the thermodynamic parameters it has been suggested that the acting force be mainly hydrophobic force. The comparison of binding potency of the three isoflavonoids to BSA showed that the substitution by 5-OH and 8-Glc could enhance the binding affinity. All these obtained in the work can make us better understand the mode of the action and pharmacological activities of the isoflavonoids.     

Design, Synthesis and Synergistic Effects of Novel Derivatives of Solanesol

To further explore the biological activities of solanesylamine derivatives,several novel solanesylpiperazinotriamines and their amides were designed and synthesized,the chemical structures of target compounds were confirmed by IR,1H NMR,MS,and element analysis.The in vitro antitumor activities of the synthetic compounds were assessed by MTT test on L1210 and CHO cells.The preliminary results showed that at low micromolar concentrations these compounds exhibit obvious toxicity against tumor cells,and the synergistic effect on clinical antitumor agent indicated that at noncytotoxic concentrations,they also evidently enhance the curative effect of vincristine(VCR).The synergistic effects of compounds 4a,4c,and 9 were even superior to that of reference compound N,N'-bis(3,4-dimethoxybenzyl)-N-solanesyl-ethylenediamine(SDB).     

Microcalorimetric Investigation of Toxic Effects of Three Injectable Solubilizing Excipients on Tetrahymena thermophila BF5 Growth

Using microcalorimetry, thermal metabolic curves of Tetrahymena thermophila BF₅ (T. thermophila BF₅) growth at 28°C affected by three injectable solubilizing excipients (ISE) including tween 80, hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) and poloxamer 188 were measured. Meanwhile, the toxicities of three ISE were evaluated by dynamic parameters of thermal metabolic curves. In addition, the irritative effects of the ISE on myoblast L₆ cells were investigated to show their cytotoxicities by biochemical method. The results indicated that the effects of the ISE on T. thermophila BF₅ varied for different ISE. 5% inhibition concentration values (IC₅) of the ISE were 1.33, 1.83 and 1.64 mg/mL for tween 80, HP‐β‐CD and poloxamer 188, respectively. By the principal component analysis (PCA), the total quantity of heat (Q), growth rate constant (k) and second maximum power (P₂) were selected as the main characteristic parameters to present their toxicities, there were good linear relationships between Q, k, P₂ and concentrations c, suggesting that the toxicities of the ISE on T. thermophila BF₅ were closely linked to their concentrations. The results of creatine kinase (CK) bioassay of myoblast L₆ cells indicated that the sequence of irritative effects of the ISE was HP‐β‐CD相似文献   

A new hydronaphthalenone from the mangrove-derived Daldinia eschscholtzii PSU-STD57

One new hydronaphthalenone derivative (1) was isolated from the broth extract of the endophytic fungus Daldinia eschscholtzii PSU-STD57 together with five known compounds, isosclerone (2), 8-methoxy-1-naphthol, 1,8-dimethoxynaphthalene, 2,6-dihydroxyphenyl-1-butan-1-one and tyrosol. The structures were assigned by spectroscopic methods. All the compounds were tested for antimicrobial activity against Staphylococcus aureus, methicillin-resistant S. aureus and Microsporum gypseum.     

Synthesis and characterization of new complexes of the type [Ru(CO)2Cl2 (2‐phenyl‐1,8‐naphthyridine‐kN) (2‐phenyl‐1,8‐naphthyridine‐kN′)]. Preliminary applications in homogeneous catalysis

Novel ruthenium (II) complexes were prepared containing 2‐phenyl‐1,8‐naphthyridine derivatives. The coordination modes of these ligands were modified by addition of coordinating solvents such as water into the ethanolic reaction media. Under these conditions 1,8‐naphthyridine (napy) moieties act as monodentade ligands forming unusual [Ru(CO)₂Cl₂(η¹‐2‐phenyl‐1,8‐naphthyridine‐ kN )(η¹‐2‐phenyl‐1,8‐naphthyridine‐kN′)] complexes. The reaction was reproducible when different 2‐phenyl‐1,8‐naphthyridine derivatives were used. On the other hand, when dry ethanol was used as the solvent we obtained complexes with napy moieties acting as a chelating ligand. The structures proposed for these complexes were supported by NMR spectra, and the presence of two ligands in the [Ru(CO)₂Cl₂(η¹‐2‐phenyl‐1,8‐naphthyridine‐ kN )(η¹‐2‐phenyl‐1,8‐naphthyridine‐kN′)] type complexes was confirmed using elemental analysis. All complexes were tested as catalysts in the hydroformylation of styrene showing moderate activity in N,N′‐dimethylformamide. Copyright © 2008 John Wiley & Sons, Ltd.     

A microcalorimetric assay of tetrahymena thermophila for assessing tributyltin acute toxicity

The power-time curves of Tetrahymena thermophila exposed to tributyltin (TBT) were detected by microcalorimetry. Metabolic rate (r) decreased significantly while peak time (PT) increased with the enhancement of TBT level. Compared with the measured multibiomarker including catalase, lactate dehydrogenase, glutathione S-transferase, ATPase and membrane fluidity, PT and r could be sensitive biomarkers for assessing TBT toxicity at cellular level. The effective concentrations obtained by them were consistent to those obtained by the protozoan community toxicity test. As a result, the microcalorimetric assay of T. thermophila had a great potential in assessing TBT acute toxicity and monitoring TBT pollution in the freshwater ecosystem.     

Synthesis of New DNA G‐Quadruplex Constructs with Anthraquinone Insertions and Their Anticoagulant Activity

1,4‐Dihydroxyanthraquinone and 1,8‐dihydroxyanthraquinone were alkylated with 3‐bromopropan‐1‐ol and subsequently transformed into the corresponding DMT protected phosphoramidite building blocks for insertion into loops of the G‐quadruplex of the thrombin binding aptamer (TBA). The 1,4‐disubstituted anthraquinone linker led to a significant stabilization of the G‐quadruplex structure upon replacing a T in each of two neighboring lateral TT loops and a 26.2° increase in thermal melting temperature was found. CD Spectra of the modified quadruplexes confirmed anti‐parallel conformations in all cases under potassium buffer conditions as previously observed for TBA. Although the majority of the anthraquinone modified TBA analogues showed a decrease in clotting times in a fibrinogen clotting assay when compared to TBA, modified aptamers containing a 1,8‐disubstituted anthraquinone linker replacing G₈ or T₉ in the TGT loop showed improved anticoagulant activities. Molecular modeling studies explained the increased thermal melting temperatures of anthraquinone‐modified G‐quadruplexes.     

Green synthesis and characterization of monodispersed silver nanoparticles obtained using oak fruit bark extract and their antibacterial activity

Green synthesis of silver nanoparticles (Ag NPs) has been achieved using oak fruit bark extract as a reducing, capping and stabilizing agent. The biosynthesized Ag NPs were characterized using various techniques. UV–visible spectrum of prepared silver colloidal solution showed absorption maximum at 433 nm. X‐ray diffraction and transmission electron microscopy analysis revealed that Ag NPs have a face‐centred cubic structure being spherical in shape with an average particle size of 20–25 nm. The toxicity of the Ag NPs was tested on bacterial species such as Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli by comparison based on diameter of inhibition zone in disc diffusion tests and minimum inhibitory concentration and minimum bactericidal concentration of NPs dispersed in liquid cultures. The antimicrobial activity of Ag NPs was greater towards Gram‐positive bacteria (S. aureus and B. subtilis) compared to Gram‐negative bacteria as determined using standard Kirby–Bauer disc diffusion assay and serial dilution. Copyright © 2016 John Wiley & Sons, Ltd.     

A Selective Film Based on Poly(3‐octylthiophene) Doped with Dihydroxyanthraquinone Sulfonate

A stable film of poly(3‐octylthiophene)–dihydroxyanthraquinone sulfonate has been synthesized electrochemically in non‐aqueous solution. The incorporation of dihydroxyanthraquinone sulfonate as an anionic complexing ligand into poly(3‐octylthiophene) film during electropolymerization was achieved and copper ions were accumulated by reduction on the electrode surface. The presence of dihydroxyanthraquinone sulfonate during the electrochemical polymerization of 3‐octylthiophene is shown to impact the sensitivity and the stability of the organic conducting film electrode response. The electroanalysis of copper(II) ions using conducting polymer electrode was achieved by differential pulse anodic stripping voltammetry with remarkable selectivity. The analytical performance was evaluated and linear calibration graphs were obtained in the concentration range of 50–400 ng mL^?1 copper(II) ion for 240 seconds accumulation time and the limit of detection was found to be 7.8 ng mL^?1. To check the selectivity of the proposed stripping voltammetric method for copper(II) ion, various metal ions as potential interferents were tested. The developed method was applied to copper(II) determination in certified reference material, NWRI‐TMDA‐61, trace elements in fortified water.     

Synthesis and biological evaluation of novel fused indolo [3, 2-c] [1,8] naphthyridine derivatives as potential antibacterial agents

Nine novel fused indolo [1,8] naphthyridine derivatives were synthesized using the Povarov reaction, in a one-pot system, and were fully characterized by spectroscopic techniques such as FT-IR, NMR, TOF-MS, and elemental analysis. Furthermore, their antibacterial activities against six bacterial strains were assessed. The results of the bioassay demonstrated that compounds 4a, 4c, and 4i showed good inhibitory effect with a MIC value ranging from 0.04687 to 0.09375?µM against Bacillus cereus and Staphylococcus aureus. The toxicity of 4a–i, evaluated through mutagenicity test against Salmonella typhimurium TA 98 and TA100 strains, revealed that there was no significant increase in the number of revertant colonies in comparison with the control, sodium azide.     

Synthesis and Antimicrobial Evaluation of 1,4-Naphthoquinone Derivatives as Potential Antibacterial Agents

1,4-Naphthoquinones are an important class of compounds present in a number of natural products. In this study, a new series of 1,4-naphthoquinone derivatives were synthesized. All the synthesized compounds were tested for in vitro antimicrobial activity. In this present investigation, two Gram-positive and five Gram-negative bacterial strains and one pathogenic yeast strain were used to determine the antibacterial activity. Naphthoquinones tested for its antibacterial potencies, among seven of them displayed better antimicrobial activity against Staphylococcus aureus (S. aureus; 30–70 μg/mL). Some of the tested compounds showed moderate to low antimicrobial activity against Pseudomonas aeruginosa (P. aeruginosa) and Salmonella bongori (S. bongori; 70–150 μg/mL). In addition, most active compounds against S. aureus were evaluated for toxicity to human blood cells using a hemolysis assay. For better understanding, reactive oxygen species (ROS) generation, time-kill kinetic study, and apoptosis, necrosis responses were investigated for three representative compounds.     

Synthesis,molecular docking studies,and absorption,distribution, metabolism,and excretion prediction of novel sulfonamide derivatives as antibacterial agents

A series of novel sulfonamide‐amide derivatives were synthesized from 3‐(2,4 dichlorophenylamino)‐3‐oxopropane‐1‐sulfonylchloride and a variety of amines under solvent‐free conditions at room temperature. 3‐(2,4‐dichlorophenylamino)‐3‐oxopropane‐1 sulfonylchloride was synthesized in four steps starting from 2,4‐dichloroaniline and chloropropanoic acid in good yield and purity. The synthesized compounds were screened for their in vitro antibacterial activity against Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 29213). Molecular docking of sulfonamide derivatives into S. aureus tyrosyl‐tRNA synthetase (TyrRS)‐active site was also performed and among these, 5m and 5g tightly fit the active sites that might be inhibitors of TyrRS for further investigations. Also in the silico metabolism profile, drug‐like properties and absorption, distribution, metabolism, excretion and toxicity (ADMET) of the title compounds were calculated by the preADMET server.