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1.
Abstract

The chemical composition of Tussilago farfara L. essential oil from the Saguenay-Lac-St-Jean region of Quebec, Canada was analyzed by gas chromatography–flame ionisation detector (GC-FID) and gas chromatography–mass spectrometry (GC-MS), and the antibacterial activity of the oil was tested against Escherichia coli and Staphylococcus aureus. Forty-five (45) compounds were identified from the GC profile. The main components were 1-nonene (40.1%), α-phellandrene (26.0%) and ρ-cymene (6.6%). The essential oil demonstrated antibacterial activity against E. coli (MIC50 = 468 µg·mL?1; MIC90 = 6869 µg·mL?1) and S. aureus (MIC50 = 368 µg·mL?1; MIC90 = 773 µg·mL?1). Dodecanoic acid was found to be active against both bacteria having a MIC50 and MIC90 of 16.4 µg·mL?1 and 95 µg·mL?1, respectively for E. coli and a MIC50 and MIC90 of 9.8 µg·mL?1 and 27.3 µg·mL?1, respectively for S. aureus. In addition, 1-decene and (E)-cyclodecene were also found to be active against E. coli.  相似文献   

2.
Two new Schiff base silver(I) complexes, {[Ag(L1)][H2O]} (1) and {[Ag(L2)][H2O]} (2), where L1 = 4-((2-diethylaminoethylimino)methyl)phenecarboxylate and L2 = 4-([3-(morpholin-4-yl)propyl]iminomethyl)phenecarboxylate, have been synthesized and characterized. X-ray crystallographic analysis reveals that silver ions in 1 are bridged by L1 to form a one-dimensional zigzag chain, while three silver ions in 2 are linked by L2 to produce a two-dimensional coordination polymer. Guest water molecules in 1 generate a one-dimensional hydrogen-bonded chain. Both 1 and 2 offer high antibacterial activity against Gram-positive bacteria Staphylococcus aureus with MIC values of 0.26 and 0.24 mM and to exhibit good inhibitory activity against urease with the respective IC50 values of 3.5 ± 0.1 and 3.8 ± 0.2 μM.  相似文献   

3.
Silver(I) and copper(II) complexes of 4-amino-N-(4,6-dimethyl-2-pyrimidinyl) benzenesulfonamide (smz) have been synthesized and characterized by elemental analysis and infrared (IR), 1H NMR, and UV–vis spectroscopy. [Ag(smz)(pyridine)] (1) crystallizes in monoclinic system with space group P21/c and Z = 4, while [Cu(smz)2(pyridine)2]·H2O (2) crystallizes in triclinic system with space group P-1 and Z = 2. X-ray analysis revealed that silver in 1 is four-coordinate exhibiting distorted tetrahedral geometry, while copper in 2 is coordinated to six nitrogens leading to a highly distorted octahedral geometry. The molecular structures of both 1 and 2 are stabilized by N–H?O and C–H?π intermolecular and C–H?O intramolecular interactions. Water plays a significant role in crystal packing by forming strong N–H?Owater intramolecular as well as Owater–H?N intermolecular interactions in 2. The results of IR, UV–vis, 1H NMR spectral data and thermal analysis for 1 and 2 suggest that the binding of silver and copper to the sulfonamidic nitrogen is in agreement with the crystal structure determination. Antimicrobial activities of silver (1) and copper (2) complexes of sulfamethazine are studied by the dilution method against Staphylococcus aureus and Escherichia coli strains.  相似文献   

4.
A silver(I) coordination polymer, [Ag2(bpdc)] n (1) (H2bpdc = 2,2-bipyridyl-3,3-dicarboxylic acid), has been synthesized and characterized. Compound 1 exhibits a 2-D network containing 1-D channels. Each (bpdc)2? is an octadentate μ6-1igand coordinating with six Ag(I)'s in 1. This coordination of (bpdc)2? ligand is first observed here. Neighboring networks are arranged in a [ABAB···] pattern to form 3-D supramolecular architecture by π···π stacking. Compound 1 shows intense photoluminescence at room temperature.  相似文献   

5.
A polymeric silver(I) complex, [Ag4(μ-pydc)2(μ-pm)2]n (1) (pydc = pyridine-3,5-dicarboxylate and pm = pyrimidine), has been synthesized and characterized by elemental analysis, IR spectroscopy, thermal analysis, and single-crystal X-ray diffraction. X-ray crystallographic data of 1 revealed that pydc exhibits two different coordinaton modes that play a key role in the construction of the 3-D crystal network including Ag–carboxylate clusters in which close Ag–Ag distances exist. The magnitudes of close Ag–Ag interactions in second-order energy (E2) have been revealed by natural bond orbital analysis performed with single point energy calculation using the experimental geometry of 1. Furthermore, the luminescent properties of 1 show strong fluorescence with two emission maxima in the visible region. Also, 1 has antifungal activity on Candida albicans (MIC value, 4 μg mL?1) and good antibacterial activity on micro-organisms (MIC value, 64–256 μg mL?1).  相似文献   

6.
An N3O Schiff base (L), 1?:?1 condensate of benzil monohydrazone and 4-pyridine carboxaldehyde, and its Zn(II), Cd(II), and Ag(I) complexes were synthesized and characterized by elemental analyses and various spectroscopic techniques. The crystal structures of [ZnL2Br2] (1), [CdL2I2]·CH2Cl2, (2)·CH2Cl2, and [Ag(L)2]ClO4 (3) have been determined using X-ray crystallography. The Zn(II) and Cd(II) complexes show a tetrahedral configuration whereas in the asymmetric unit of 3, two independent coordination units of Ag(I) are present. Carbonyl–silver interaction, weak C–H?O interaction, and also π–π interaction are present in 3 in the solid state. The synthesized complexes have antibacterial activity against Klebsiella pneumoniae 114, Escherichia coli K88, Salmonella typhi ATCC 34, Bacillus subtilis UC564, and Staphylococcus aureus ATCC25923. The results showed that in some cases the antibacterial activities of the complexes were comparable to standard antibiotics Tetracycline and Streptomycin. The antifungal activities of the complexes were also studied for Aspergillus niger, Aspergillus oryzae, Penicillium notatum, and Saccharomyces cerevisiae. MIC values of 1, 2·CH2Cl2, and 3 are less than the Nystatin standard.  相似文献   

7.
MOF-5 that sometimes called IRMOF-1 has been intensively studied in recent years to develop efficient photocatalyst to degrade refractory organics and inactivate bacteria for wastewater treatment. In the present work, Ag/Ag3PO4 nanoparticles incorporated in IRMOF-1 was successfully prepared via hydrothermal approach. The antibacterial activity of synthesized materials (IRMOF-1, Ag/Ag3PO4 nanoparticles and Ag/Ag3PO4-IRMOF-1 nanocomposite was compared against two types of bacteria (Escherichia coli (E. coil) as Gram negative and Staphylococcus aureus (S. aureus) as Gram-positive bacteria). The deactivation of the bacteria by the prepared material was measured in the dark and under visible light irradiation. The antibacterial activity of synthesized samples was investigated by determining the minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), growth inhibition assay and inhibition zone. The Ag/Ag3PO4-IRMOF-1 nanocomposite exhibited stronger antibacterial activities than the Ag/Ag3PO4 nanoparticles and IRMOF-1 at all tested bacteria types. Based on inhibition zone, without any light irradiation, Ag/Ag3PO4-IRMOF-1 nanocomposite showed activity toward E. coil, but in presence of light nanocomposite depicted activity toward S. aureus. The results demonstrated that antibacterial activity of all synthesized samples in the dark and light against S. aureus bacteria was more than E. coil bacteria. The antibacterial activity mechanism was due to sustained-release of silver ions in the dark and reactive oxygen species (ROS) under visible light. The bioactivity of IRMOF-1 was related to the degradation of the its structure and the release of Zn2+ ions into the culture medium that bind to the cell wall and deactivation bacteria.  相似文献   

8.
Four coordination polymers, [Ag(L1)](m-Hbdc) (1), [Ag(L1)]2(p-bdc)?·?8H2O (2), [Ag(Hbtc)(L1)][Ag(L1)]?·?2H2O (3) and [Ag2(L2)2](OH-bdc)2?·?4H2O (4), where L1?=?1,1′-(1,4-butanediyl)bis(imidazole), L2?=?1,2-bis(imidazol-1-ylmethyl)benzene, m-H2bdc?=?1,3-benzenedicarboxylic acid, p-H2bdc?=?1,4-benzenedicarboxylic acid, H3btc?=?1,3,5-benzenetricarboxylic acid, and OH–H2bdc?=?5-hydroxisophthalic acid, were synthesized under hydrothermal conditions. Compound 1 contains a–Ag-L1–Ag-L1–chain and a hydrogen-bonding interaction induced–(m-Hbdc)-(m-Hbdc)–chain. Compound 2 consists of two independent–Ag-L1–Ag-L1–chains. P-bdc anions are not coordinated. Hydrogen bonds form a 3D supramolecular structure. A novel (H2O)16 cluster is formed by lattice water molecules in 2. Compound 3 contains a–Ag-L1–Ag-L1–and a–Ag(Hbtc)-L1–Ag(Hbtc)-L1–chain. The packing diagram shows a 2D criss-cross supramolecular structure, with?π?···?π?and C–H ···?π?interactions stabilizing the framework. Compound 4 contains a [Ag2(L2)2]2+ dimer with hydrogen-bonding,?π?··· π, and Ag ··· O interactions forming a 3D supramolecular framework. The luminescent properties for these compounds in the solid state are discussed.  相似文献   

9.
Pure and silver doped nanoparticles of titanium dioxide (TiO2) was prepared using novel, modified sol–gel method. The samples were characterized by transmission electron microscopy, X-ray diffraction, N2 adsorption measurement, atomic absorption spectroscopy (AAS), UV–vis spectroscopy (UV–vis). The antibacterial activity of the prepared samples was indicated by minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) values according to the reference methods of Clinical and Laboratory Standards Institute for the determination of MIC of aerobic bacteria by broth microdilution. The results showed very good antibacterial activity of silver nanoforms to bacteria strains: Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli and Klebsiella pneumoniae. The sensitivity of the tested bacteria to silver nanoforms depends on the crystalline form of the carrier—TiO2, its surface area, porosity, the content of silver, its particle size and oxidation state. The originality of this work is the synthesis of novel type of nanocomposites TiO2 doped with silver and determination its excellent antibacterial activity.  相似文献   

10.
Hydrothermal reactions of ciprofloxacin with Cu(ClO4)2?·?6H2O, and ofloxacin with Cu(CH3COO)2?·?4H2O, yield two metal complexes: [Cu(H-Cip)2]?·?(ClO4)2?·?6H2O (1) and [Cu(Ofl)2?·?H2O]?·?2H2O (2), which were characterized by elemental analysis, IR and single crystal diffraction analyses. Compounds 1 and 2 were screened for antibacterial activities against Staphylococcus aureus, Escherichia coli, Candida albicans and pseudomonas aeruginosa.  相似文献   

11.
A silver(I) complex with nitronyl nitroxide, [Ag2(NIT-R)4(NO3)2]?·?CH3OH [NIT-R?=?2-(5-methylimidazol-4-yl)-4,4,5,5-tetramethyl-2-imidazoline-1-oxyl-3-oxide], has been prepared and characterized by magnetic and single-crystal X-ray diffraction studies. In the complex, the silver(I) ion is coordinated with two monodentate nitronyl nitroxide radicals by the nitrogen of the imizadole ring. The silver(I) ion is two-coordinate and forms a dimer through Ag?···?Ag weak metal bonding interactions. The magnetic properties for the title complex have been investigated in the temperature range 2?~?300?K showing ferromagnetic interactions between the coordinated nitronyl nitroxides (J?=?3.64?cm?1) and intermolecular antiferromagnetic interactions.  相似文献   

12.
Interfacial polymerization technology was employed to immobilize silver (Ag) nanoparticles on the surface of commercial polyethersulfone (PES) membrane to develop antibacterial and antifouling ultrafiltration membrane. Ag nanoparticles were prepared from the reduction of silver nitrate (AgNO3) by sodium borohydride in the presence of polyethyleneimine (PEI) as the stabilizer. The encapsulated Ag nanoparticles in the PEI solution were embedded into the PEI membrane when trimesoyl chloride solution was used to crosslink the PEI solution with the PES membrane, forming Ag-polyamide (PA) networks through the interfacial polymerization reaction. Experimental results showed that the membrane prepared with 50 mmol/L of AgNO3 and 20 mmol/L of PEI had the optimized antibacterial effect against Escherichia coli. Bacterial concentration and species were also investigated. Exiguobacterium aestuarii and Staphylococcus aureus which are gram-positive bacteria, needed significantly more time for the Ag-PA/PES membrane to kill the bacteria completely when compared to E.coli and Vibrio coralliilyticus which are gram-negative bacteria. This study showed that Ag nanoparticles impregnated in membrane surfaces were 100% effective in killing various types of marine bacteria and bacteria in the seawater collected off Sentosa Island in Singapore. These membranes exhibit excellent antibacterial and antifouling properties which can be used to kill bacteria in ballast water and seawater.  相似文献   

13.
Two new Schiff bases (2,4-diiodo-6-[(2-morpholin-4-yl-ethylimino)-methyl]-phenol and 2,4-diiodo-6-[(3-morpholin-4-yl-propylimino)-methyl]-phenol), condensed from 3,5-diiodosalicylaldehyde with 2-morpholinoethylamine and 3-morpholinopropylamine, have been designed and synthesized. Reaction of the Schiff bases with Zn(OAc)2 · 2H2O, Cu(OAc)2 · H2O, Ni(OAc)2 · 4H2O, Co(OAc)2 · 4H2O, Cd(OAc)2 · 2H2O, Mn(OAc)2 · 4H2O, Fe(SO4)2 · 7H2O, and Hg(OAc)2 led to the formation of 16 new mononuclear complexes. The complexes were characterized by UV, Infrared, ESI-MS, and elemental analyses, and 3,5-diiodosalicylalidene-2-morpholinoethylaminozinc(II) (1) and 3,5-diiodosalicylalidene-2-morpholinoethylaminocopper(II) (2) were characterized by single crystal X-ray diffraction. Based on crystal structural analysis of 1 and 2, coupled with their spectral similarity with 316, it can be concluded that 316 have structures similar to 1 and 2. All the complexes were assayed for antibacterial activities against three Gram positive bacterial strains (Bacillus subtilis, Staphylococcus aureus, and Streptococcus faecalis) and three Gram negative bacterial strains (Escherichia coli, Pseudomonas aeruginosa, and Enterobacter cloacae) by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide method. Among the complexes tested, 8 and 16 showed the most favorable antibacterial activity with minimum inhibitory concentration of 0.781, 12.5, 6.25, 3.125, 3.125, 6.25 and 1.562, 6.25, 1.562, 3.125, 3.125, 1.562 µg mL?1 against B. subtilis, S. aureus, S. faecalis, P. aeruginosa, E. coli, and E. cloacae, respectively.  相似文献   

14.
Seven new mononuclear complexes have been synthesized from 2,4-diiodo-6-propyliminomethyl-phenol in pyridine and Cu(OAc)2 · H2O, Ni(OAc)2 · 4H2O, Co(OAc)2 · 4H2O, Zn(OAc)2 · 2H2O, Cd(OAc)2 · 2H2O, Mn(OAc)2 · 4H2O, and Hg(OAc)2. The complexes were characterized by UV, IR, ESI-MS, and elemental analyses; bis(2,4-diiodo-6-propyliminomethyl-phenol)-pyridine-copper(II) (1) was characterized by X-ray crystallography. The central metal in each complex is five-coordinate by two nitrogens and two oxygens from two 3,5-diiodosalicylaldehyde Schiff-base ligands and one nitrogen from pyridine. The 3,5-diiodosalicylaldehyde Schiff base is bidentate. All the complexes were assayed for antibacterial (Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter cloacae) activities by the MTT method. Complex 1 showed the most favorable antimicrobial activity with minimum inhibitory concentrations of 6.25, 3.125, 6.25, 3.125, 6.25, 3.125 µg mL?1 against B. subtilis, S. aureus, S. faecalis, P. aeruginosa, E. coli, and E. cloacae, respectively.  相似文献   

15.
设计合成了4种含不同芳香取代基团的肼基二硫代甲酸甲酯配体(2-乙酰基吡啶肼基二硫代甲酸甲酯(L1-H)、2-甲酰基吡啶肼基二硫代甲酸甲酯(L2-H)、2-甲酰基噻吩肼基二硫代甲酸甲酯(L3-H)、2-甲酰基水杨醛肼基二硫代甲酸甲酯(L4-H))的镓配合物,对它们的抑菌活性进行了测试,并讨论了配体分子中不同芳香取代基对配合物抑菌活性的影响。在模拟生理条件下,L与Ga3+生成较稳定的单核配合物[Ga(L12]NO31)、[Ga(L22]NO32)、[Ga(L32]NO33)、[Ga(L42]NO34),各配合物对金黄色葡萄球菌和大肠杆菌表现出比Ga(NO33·9H2O强的抑制活性,抑制金黄色葡萄球菌的能力高于大肠杆菌,其中,12的活性比相应配体高,其余2个配合物与其配体之间无明显活性差异。L1和L2分子中吡啶基的较强吸电子效应可能是12具有较强抑菌活性的主要原因。4种配合物抑制黑曲霉生长的活性同样高于Ga(NO33·9H2O,其中3最强,并显著高于L3,其余配合物与相应配体间无活性差异。  相似文献   

16.
A series of unsymmetrically substituted N‐heterocyclic carbene (NHC) precursors ( 1a , 1b , 1c , 1d , 1e ) were synthesized from the reaction of N‐phenylbenzimidazole with various alkyl halides. These compounds were used to synthesize NHC–silver(I) complexes ( 2a , 2b , 2c , 2d , 2e ). The five new 1‐phenyl‐3‐alkylbenzimidazolium salts ( 1a , 1b , 1c , 1d , 1e ) and their NHC–silver complexes ( 2a , 2b , 2c , 2d , 2e ) were characterized by the 1H NMR, 13C NMR and FT‐IR spectroscopic methods and elemental analysis techniques. Also, the two NHC–silver complexes 2b and 2c were characterized by single‐crystal X‐ray crystallography, which confirmed the linear C―Ag―Cl arrangements. The antibacterial activities of the NHC precursor and NHC–silver complexes were tested against three Gram‐positive bacterial strains (Bacillus subtilis, Listeria monocytogenes and Staphylococcus aureus) and three Gram‐negative bacterial strains (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) using the microdilution broth method. The NHC–silver complexes showed higher antibacterial activity than the NHC precursors. In addition, silver complexes 2a , 2b , 2c , 2d showed high antibacterial activity against the Gram‐positive bacteria L. monocytogenes and S. aureus compared to the standard, tetracycline. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

17.
Bamboo charcoal supporting silver (BC/Ag) was prepared by activation and chemical reduction. The BC/Ag composites were characterized by silver particle size and distribution, silver ion (Ag+) release and antibacterial properties. Scanning and transmission electron microscopy (SEM and TEM) showed that the Ag particles were distributed uniformly on the BC matrix. The Ag particle size was found to be less than 150 nm based on TEM. The Ag+ release increased initially which was followed by a marginal increase between the 8th and 24th hour. Composites contained higher amounts of silver exhibited a further rise in Ag+ release from the 24‐hours of storage in water. The antibacterial effects of the BC/Ag composite powders against Pseudomonas aeruginosa and Staphylococcus aureus were assessed from the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) method, and an excellent antibacterial performance was discovered.  相似文献   

18.
Ag nanoparticle-embedded one-dimensional β-CD (β-cyclodextrin)/PVP composite nanofibers were prepared using a one-step electrospinning technique. Ag nanoparticles were obtained in the AgNO3/β-CD/DMF solution, in which silver nitrate been introduced as the precursor, DMF as solvent, β-CD as reducing and capping agent. After electrospinning of the composite solution at room temperature, the β-CD/PVP nanofibers containing Ag nanoparticles were obtained. The electrospun composite solution containning Ag nsnopsrticles were confirmed by UV-visible absorption spectra; the resulting composite nanofibers were characterized by scanning electron microscopy , transmission electron microscopy, and X-ray diffraction. Ag-β-CD/PVP nanofiber exhibits good antibacterial property for Escherichia coli and Staphylococcus aureus. Consequently, we propose that these Ag nanoparticle-embedded 1D-nanostructures prepared via electrospinning may be used as antibacterial material.  相似文献   

19.
The possibility of using a corona treatment (electrical discharge at atmospheric pressure) for fiber surface activation, which can facilitate the loading of silver nanoparticles (NPs) from colloids onto the polyester (PES) and polyamide (PA) fabrics and thus improve their antibacterial properties, was studied. Bactericidal efficiency and its laundering durability on silver‐loaded fabrics for Gram‐positive bacterium Staphylococcus aureus and Gram‐negative bacterium Escherichia coli were evaluated. The fiber morphology after corona treatment and subsequent loading of silver NPs was followed by SEM. Corona‐treated fabrics loaded with silver NPs exhibited better antibacterial properties in comparison with untreated fabrics. In order to obtain acceptable laundering durability, it is necessary to use highly concentrated silver colloids. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

20.
Abstract

Mangrove plants are endowed with various biologically active compounds which have potent antibacterial and antioxidant properties. In present study, a bioactivity-guided fractionation for antibacterial and antioxidant active metabolites from the twigs of Avicennia officinalis collected from Kuala Selangor Nature Park, Selangor, Malaysia gave 13 major fractions. The antibacterial activity of A. officinalis fractions using well-diffusion showed strong selectivity on the Gram-positive bacteria (Staphylococcus epidermidis, S. aureus and Bacillus subtilis) with minimum inhibition concentration (MIC) values of 0.156-5.00?mg/mL. However, no antibacterial activities were observed on the Gram-negative bacteria (Vibrio cholera, Enterobacter cloacae and Escherichia coli). The active antibacterial fractions were further isolated using several chromatographic techniques to give two naphthofuranquinones, namely, avicenol C (1) and stenocarpoquinone B (2). Meanwhile, the antioxidant activity of A. officinalis fractions were evaluated using DPPH radical scavenging assay exhibited low antioxidant activities. Molecular structure of the naphthofuranquinones was elucidated using 1?D and 2?D NMR spectroscopy.  相似文献   

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