Microwave Activated Solid Support Synthesis of New Antibacterial Quinolones

Summary.  A novel synthesis of 6-fluoro-7-(5-aryl-1,3,4-thiadiazol/oxadiazol-2-yl-sulfanyl)-4-quinolone-3-carboxylic acids from 7-chloro-6-fluoro-4-quinolone-3-carboxylic acid and 5-substituted 1,3,4-thiadiazoles/oxadiazoles on basic alumina under microwave activation is described. All compounds were screened for their in vitro antibacterial activity against B. lichenformis, 2689, K. aerogens 2281, S. typhimurium 2501, E. herbicola 2491, and P. vulgaris 2027 and found to possess activities comparable to that of the standard drug norfloxacin. Received May 2, 2000. Accepted (revised) June 13, 2000     

Synthesis, Characterization, and Antibacterial Activity of Complexes of (1S,2S)-N,N-1,2-Diphenylethylene-bis-(5-imino-1-phenyl-1,3-hexanedione)

Summary.  The synthesis and characterization of homobimetallic complexes of VO(IV), Cr(II), Co(II), Ni(II), and Cu(II) with the chiral Schiff base (1S,2S)-N,N-1,2-Diphenylethylene-bis-(5-imino-1-phenyl-1,3-hexa-nedione) is reported. The metal ions occupy both compartments of the ligand; water molecules fill the coordination spheres to provide an octahedral environment around the central atoms. The antibacterial activity of both mono- and bimetallic complexes against a number of Gram-positive as well as Gram-negative bacteria has been tested and is discussed. Received March 28, 2000. Accepted May 26, 2000     

Synthesis of some sulfonamide derivatives with potential antibacterial activity

Some new quinoxaline-6-sulfonamide and phthalazine-6-sulfonamide derivatives were synthesized. The majority of the prepared compounds showed antibacterial activity.Faculty of Pharmacy, University of Tanta, Egypt. Fax: 002 040 335466Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 523–528, April, 2000.     

<Emphasis Type="Italic">ε</Emphasis>-Poly(L-lysine)-based Hydrogels with Fast-acting and Prolonged Antibacterial Activities

Bacterial infections and the associated morbidity and mortality due to bacterial pathogens in wounds and medical implants have been increasing as most of current coatings cannot fulfill all the requirements including excellent intrinsically antibacterial activity, low cytotoxicity, and favorable physical properties. Herein, we present a kind of antibacterial hydrogel based on ε-poly(L-lysine) (EPL) grafted carboxymethyl chitosan (CMC-g-EPL) as the inherently antibacterial matrix and the surplus EPL as highly efficient antimicrobial agent. Such hydrogels possess tunable swelling abilities with water absorption percentages of 800%-2000% and modulus varying from 10 kPa to 100 kPa, and exhibit two-stage excellent antibacterial behavior. First, the free EPL can be released from the hydrogel network for quick and highly efficient bacteria killing with 99.99% of efficacy; second, the grafted EPL endows hydrogel matrix with prolonged intrinsically antibacterial activity, especially when most of free EPL is released from the hydrogel. Overall, we provide a new insight for preparing highly effective antibacterial hydrogels.     

载银磷酸活化剑麻基活性炭纤维的抗菌性能研究

本文利用磷酸化方法，制备各种剑麻基活性炭纤维，并利用活性炭纤维的氧化还原特性及吸附性能，在其上负载金属银，研究并比较了这些载银活性炭纤维对大肠杆菌和金黄色葡萄球菌的杀灭作用，结果表明，磷酸浓度，活化方法，活化时间，纤维的比表面积等因素的均对材料的抗菌性能有一定的影响，磷酸活化的活性炭纤维表现出强的抗菌杀菌能力，高浓度磷酸活化后的纤维抗菌能力有所提高，并且抗菌能力随活化时间的延长而增加，抗菌前后纤维上负载的银未曾大量脱落，经5次抗菌试验后材料仍显示出很强的抗菌能力。     

Preparation and Characterization of the Antibacterial Zn2+ or/and Ce3+ Loaded Montmorillonites

A series of modified montmorillonites including Zn²⁺ loaded montmorillonite (Zn/MMT), Ce³⁺ loaded montmorillonite (Ce/MMT) and Zn²⁺‐Ce³⁺ loaded montmorillonites (Zn‐Ce/MMT) were prepared by an ion‐exchange reaction, and characterized using X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), and scanning electron microscopy (SEM). The specific surface areas, zeta potentials and antibacterial activity of the modified montmorillonites were also investigated. Zinc and cerium were proved to be present as bivalent zinc state and trivalent cerium state in the modified montmorillonites. For the modified montmorillonites, the d₀₀₁ basal spacings increased and the particles were formed of irregular shapes. The antibacterial activity of the modified montmorillonites was enhanced with the increase of specific surface areas and zeta potentials, and Zn²⁺‐Ce³⁺ loaded montmorillonites displayed obvious synergistic antibacterial effect. When Zn/Ce atomic ratio was 1.24, the Zn‐Ce/MMT showed high antibacterial efficiency and broad‐spectrum antibacterial activity, possessing the MIC against Escherichia coli, Staphylococcus aureus, Candida albicans and Mucor of 1500, 1000, 2000 and 3000 mg·L^?1, respectively.     

Green synthesis and chemical characterization of silver nanoparticles obtained using Allium saralicum aqueous extract and survey of in vitro antioxidant,cytotoxic, antibacterial and antifungal properties

Allium saralicum R.M. Fritsch has been used in Iranian traditional medicine as a remedial supplement for microbial diseases. This paper reports the green synthesis, chemical characterization and antioxidant, cytotoxic, antibacterial and antifungal properties of silver nanoparticles obtained using aqueous extract of A. saralicum leaves. In this synthesis, no surfactants or stabilizers were used. For characterization, UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy and field emission scanning electron microscopy were used. 2,2‐Diphenyl‐1‐picrylhydrazyl was used in experiments to assess the antioxidant potential of the silver nanoparticles, which revealed an impressive prevention in comparison with butylated hydroxytoluene. The synthesized silver nanoparticles at low doses (1–250 μg dl^?1) did not show marked cytotoxic activity (against cervical cancer cells (Hela), breast cancer cells (MCF‐7) and human embryonic kidney cells (HEK‐293)). Agar diffusion tests were applied to determine the antibacterial and antifungal characteristics. Compared with all standard antimicrobials, the silver nanoparticles showed higher antibacterial and antifungal activities (p ≤ 0.01). Also, the silver nanoparticles inhibited the growth of all bacteria and fungi at concentrations of 31–250 μg ml^?1, and destroyed them at concentrations of 31–500 μg ml^?1 (p ≤ 0.01). Because the silver nanoparticles obtained using aqueous extract of A. saralicum leaves have antioxidant, non‐cytotoxic, antifungal and antibacterial potentials, they can be used as a medical supplement or drug.     

Synthesis of functionalized Cu:ZnS nanosystems and its antibacterial potential

Copper doped Zinc Sulfide (Cu:ZnS) nanoparticles were synthesized as potential antibacterial agents, through a solvothermal approach using Mercaptosuccinic acid (MSA) and Sodium citrate (SC) as differential capping agents. Multiple variants of the Cu:ZnS nanoparticles were generated based on the refluxing intervals of the reactions and a choice of the capping agents. The microstructural properties and the elemental composition of the synthesized nanosystems were examined using Scanning Electron Microscopy (SEM) and powder X-ray Diffraction (XRD), along with Energy-Dispersive X-ray spectroscopy (EDX) and Microwave Plasma-Atomic Emission Spectroscopy (MP-AES). The as-synthesized nanosystems were also characterized for their surface attributes using Fourier Transform Infrared spectroscopy (FT-IR), while the optical properties were studied using UV–Vis spectroscopy. The electrostatic stability of the aqueous dispersions of Cu:ZnS was studied as a function of their solvent pH, using Photon Correlation Spectroscopy. For the assessment of the antibacterial properties of the different variants of Cu:ZnS nanosystems, the disk diffusion assay was performed against both Gram-positive and Gram-negative bacteria. The results show a promising antibacterial activity for the Cu:ZnS variants synthesized, with a prominent activity in the [email protected]:ZnS nanoparticle making them a novel class of potential antibacterial agents.     

TLC–direct bioautography as a method for evaluation of antibacterial properties of Thymus vulgaris L. and Salvia officinalis L. essential oils of different origin

ABSTRACT

The dot-blot bioautography was used to evaluate the antibacterial properties of Thymus vulgaris L. and Salvia officinalis L. essential oils (EOs) produced by three different manufacturers. The whole samples were applied at three concentrations on thin-layer chromatography (TLC) plates which were then subjected to bioautography against Bacillus subtilis. The samples of the highest activity were found. Then, they were separated using TLC and once again subjected to bioautography against B. subtilis. As was proved, only the essential oils of T. vulgaris L. possessed strong antibacterial properties for which mostly thymol and carvacrol were responsible. Their contents were calculated using TLC–UV densitometry. The highest contents were found in the essential oils of the highest antibacterial activity revealed in the dot-blot test. It means that a dot-blot test can be used for simple and fast evaluation of antibacterial properties of essential oils.     

微量热研究几种新型吡啶酰胺希夫碱对大肠杆菌的抑制作用

用微量热研究一系列新型吡啶酰胺希夫碱对大肠杆菌的抑制作用, 不同的吡啶酰胺希夫碱衍生物对大肠杆菌生长的抑制作用不同. 通过热动力学模型计算得到生长速率常数(k)和抑制率(I), 我们获得了吡啶酰胺希夫碱衍生物的抗菌作用效果. 通过药物作用于细菌处于生长对数期的实验发现, 有两种化合物(F和G)对大肠杆菌生长有非常好的抑制作用, 他们的半抑制浓度(IC50)分别是0. 106 和0. 113 g/L, 但是药物对大肠杆菌的无氧发酵过程抑制作用比较差. 通过进一步分析药物结构与药物半抑制浓度, 我们发现: 希夫碱衍生物的亲水性对其抗菌活性有很大的影响, 这主要是由细菌的细胞膜结构不同所致. 对希夫碱及其碱衍物的结构与抗菌活性关系进行了初步探讨, 它们对大肠杆菌的抗菌活性顺序为: F＞G＞C＞D＞E＞B＞A.     

Zopfiellasins A–D,Two Pairs of Epimeric Cytochalasins from Kiwi-Associated Fungus Zopfiella sp. and Their Antibacterial Assessment

In our continuous search for antibacterial agents against Pseudomonas syringae pv. actinidiae (Psa) from kiwi-associated fungi, two pairs of epimeric cytochalasins, zopfiellasins A–D (1–4), were characterized from the fungus Zopfiella sp. The structures were established on the basis of spectroscopic data analysis, while the absolute configurations were determined by single-crystal X-ray diffraction. Compounds 1 and 3 exhibited antibacterial activity against Psa with MIC values of 25 and 50 μg/mL, respectively. This is the first report of anti-Psa activity of cytochalasin derivatives.     

Analytical characterization of laser-generated copper nanoparticles for antibacterial composite food packaging

A new type of nanomaterial has been developed as antibacterial additive for food packaging applications. This nanocomposite is composed of copper nanoparticles embedded in polylactic acid, combining the antibacterial properties of copper nanoparticles with the biodegradability of the polymer matrix. Metal nanoparticles have been synthesised by means of laser ablation, a rising and easy route to prepare nanostructures without any capping agent in a liquid environment. As prepared, nanoparticle suspensions have been easily mixed to a polymer solution. The resulting hybrid solutions have been deposited by drop casting, thus obtaining self-standing antibacterial packages. All samples have been characterized by UV–Vis spectroscopy, X-ray photoelectron spectroscopy and electro-thermal atomic absorption spectroscopy. Ion release data have been matched with bioactivity tests performed by Japanese Industrial Standard (JIS) method (JIS Z 2801:2000) against Pseudomonas spp., a very common Gram-negative microbial group able to proliferate in processed food.     

取代喹啉类化合物抗菌活性的定量构效关系及分子设计

采用密度泛函理论(DFT)和逐步回归分析法对15种新合成的取代喹啉类化合物进行了定量构效关系(QSAR)研究. 在B3LYP/6-31G(d,p)水平上计算了取代喹啉的量子化学参数, 通过逐步多元回归分析筛选出影响抗菌活性的主要因素, 建立了定量构效关系方程, 并用留一法交叉分析了模型的稳定性及预测能力. 结果表明, C5的亲核电子密度fNC5及C9-N1的键级BC9-N1是影响喹啉类化合物抗金黄色葡萄球菌活性的主要因素, 所得模型对该类化合物抗菌活性有较好的预测效果. 同时基于QSAR研究结果设计了4个活性较高的新喹啉衍生物.     

Amino Acid Derivatives, VI [1]: Synthesis, Antiviral, and Antimicrobial Evaluation of α-Amino Acid Esters Bearing a 1,2,3-Triazolo[4,5-d]pyrimidinedione Side Chain

Summary. A series of peptide and dipeptide derivatives conjugated with a 1,2,3-triazolo[4,5-d]pyrimidinedione residue were synthesized. The new compounds were evaluated in vitro for cytotoxicity against HAV-27 and HSV-1 and showed moderate activity. The prepared compounds were tested for antimicrobial activity against four different bacterial species, and they displayed different degrees of antibacterial activities or inhibitory actions.     

Phytochemical characterisation and bioprospection for antibacterial and antioxidant activities of Lippia alba Brown ex Britton & Wilson (Verbenaceae)

Ethanol extract and fractions obtained from fresh and dry aerial parts of Lippia alba were examined in order to determine their phytochemical composition, antioxidant capacity and antibacterial activities. The ethanol extracts and fractions exhibited an antioxidant effect by the DPPH assay, especially samples of fresh plant. HPLC analysis of the ethyl acetate fractions identified the presence of phenolic acids and flavonoids. The ethanol extract and fractions showed activity against reference and multidrug-resistant strains of Staphylococcus aureus and Enterococcus faecalis (MIC range 2000–250 μg/mL). The hexane and dichloromethane fractions of fresh plant showed better activity against reference strains of Escherichia coli (MIC of 250 and 125 μg/mL, respectively), but all extracts and fractions were less active against multidrug-resistant strains of all the Gram-negative species evaluated. The results showed that the extract and fractions of L alba aerial parts showed antibacterial activity, even against multidrug-resistant Gram-positive bacteria, and antioxidant effect (DPPH assay).     

Microwave-assisted synthesis of water-soluble styrylpyridine dye-capped zinc oxide nanoparticles for antibacterial applications

ZnO nanoparticles were successfully synthesized using a microwave method, whose surface was modified with {4-[(E)-2-(furan-2-yl)ethenyl]pyridin-1-ium-1-yl}acetate as a capping agent (1 and 3%). Their structural properties were investigated using FTIR, XRD, SEM, EDS, and UV–visible spectroscopy. XRD confirmed the Wurtzite structure for all compounds, a size of 30.6 nm for uncapped and 22.9 nm for 3% dye-capped nanoparticles were calculated from Scherer's equation. Hexagonal wurtzite shape of nanoparticles can be clearly seen in the SEM images. The DFT calculations were carried out using quantum espresso. These dye-capped ZnO nanoparticles were proved to be potential antibacterial agents, the minimum concentrations of dye-capped ZnO nanoparticles that inhibit the growth of bacteria are 1.5 mg/mL for Escherichia coli and 0.78 mg/mL for Bacillus subtilis, which are much lower than those of uncapped ZnO. The bioactivity data suggest these organic–inorganic hybrid nanoparticles emerged as a new class of antibacterial agents.     

Synthesis of gold nanoparticles using herbal Acorus calamus rhizome extract and coating on cotton fabric for antibacterial and UV blocking applications

Gold nanoparticles (AuNPs) have been synthesized by greener method using chloroauric acid as precursor and extract of Acorus calamus rhizome as reducing agent. Formation of AuNP was confirmed by the presence of Surface Plasmon Resonance (SPR) peak in UV–Visible spectral analysis. XRD and FT-IR spectral analyses were performed for characterization. SEM images show spherical morphology and HR-TEM images reveal nanosize of AuNPs. The AuNPs were then coated on cotton fabric by pad-dry-cure method and characterized by SEM with EDAX technique. The results reveal the deposition of AuNPs on the surface of cotton fabric. Uncoated cotton, neat extract coated cotton and extract containing AuNPs coated cotton fabrics were then tested for antibacterial activity against Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) bacterial strains by AATCC 100 test method. It showed that the extract containing AuNPs coated cotton fabric had higher antibacterial activity than other test samples against E. coli. UV-DRS analysis performed on extract containing AuNPs coated cotton fabric showed improved UV-blocking property than uncoated cotton fabric and neat extract coated cotton fabric.     

Synthesis, Characterization, and Biological Activity of n-Tributyltin Derivatives of Pharmaceutically Active Carboxylates

Summary.  Tributyltin(IV) derivatives of six different pharmaceutically active carboxylates were synthesized. The complexes were characterized by different analytical techniques (elemental analysis; infrared, NMR, and mass spectroscopy). ¹¹⁹Sn NMR data were also recorded in six different coordinating and non-coordinating solvents. The antibacterial activities of the compounds were tested using ten different bacteria relative to the reference drugs ampicillin and cephalexin. Received September 20, 2001. Accepted (revised) December 6, 2001     

A Mild Deoxygenation of Heteroaromatic N-Oxides by Formamidinesulfinic Acid

Summary.  Various heteroaromatic N-oxides were efficiently deoxygenated to the corresponding bases under mild conditions using formamidinesulfinic acid (thiourea S,S-dioxide). Received March 24, 2000. Accepted April 18, 2000     

Ammonium Chlorochromate Adsorbed on Montmorillonite K-10: Oxidative Deprotection of Tetrahydropyranyl Ethers Using Microwaves in a Solventless System

Summary.  Tetrahydropyranyl ethers were rapidly and selectively oxidized to the corresponding carbonyl compounds by clay supported ammonium chlorochromate under solvent free conditions using microwaves. Received July 25, 2000. Accepted September 7, 2000