Synthesis and Catalytic Evaluation of Silver Nanoparticles Synthesized with <Emphasis Type="Italic">Aloysia triphylla</Emphasis> Leaf Extract

In this investigation, we report the biosynthesis of the silver nanoparticles using Aloysia triphylla leaves extract. The as-prepared silver nanoparticles were characterized by ultraviolet–visible (Uv–vis) spectroscopy, X-ray diffractometry, scanning electron microscopy and transmission electron microscopy The infrared spectroscopy (FTIR) and Raman spectroscopy techniques were also used to evaluate the chemical groups of the plant extract involved in the silver ions bioreduction. The results indicate that as the plant extract/precursor salt ratio increases, the size of the nanoparticles decreases. Also, as the reaction temperature increases, the reduction rate increased too, resulting in the formation of smaller nanoparticles-size ranges. Uv–vis spectroscopy illustrates absorption peaks in the range of wavelengths of 430–445 nm corresponding to surface plasmon resonance band of silver nanoparticles. The X-ray diffraction (XRD) confirmed the presence of silver solids with fcc structure type. The FTIR analysis showed that the bands corresponding to phenolic compounds and the amide group were involved in the synthesis and stabilization of silver nanoparticles, respectively. The Raman studies showed bands at 1380 and 1610 cm^?1, which correspond to the aromatic and amide compounds, confirming the FTIR results. The Uv–vis results indicate the capacity of silver nanoparticles to reduce the methylene blue.     

<Emphasis Type="Italic">Z</Emphasis>-and <Emphasis Type="Italic">E</Emphasis>-conformers of <Emphasis Type="Italic">N</Emphasis>-chloroacetylcytisine

N-Chloroacetylcytisine was synthesized by acylation of (–)-cytisine. Stable Z- and E-conformers with respect to rotational isomerism around the N-12–CO bond were found in PMR spectra at room temperature. The point at which PMR resonances of the Z- and E-conformers coalesced upon heating was measured. The transition barrier between the conformers was estimated.     

Molecular properties of the copolymers of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-diallyl-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylammonium chloride and maleic acid

The hydrodynamic and conformational properties of molecules of poly(N,N-diallyl-N,N-dimethylammonium chloride) and N,N-diallyl-N,N-dimethylammonium chloride-maleic acid copolymers of different compositions in solutions with various ionic-strength and pH values, as well as of the polyelectrolyte complex based on the copolymer with dodecyl sulfate anions in chloroform, are studied. For poly(N,N-diallyl-N,N-dimethylammonium chloride) molecules in a 1 M NaCl solution, the Kuhn segment length and the hydrodynamic diameter of the chain are estimated as A = 3.9 nm and d = 0.48 nm, respectively. In acidic solutions with pH 3.5, the copolymers demonstrate behavior typical for polyelectrolytes. In an alkaline solution with pH 13, when 1 M NaCl is added to the solution of the copolymer containing 29 mol % maleic acid units, there is an antipolyelectrolyte effect that manifests itself as an increase in the intrinsic viscosity of the copolymer and in the hydrodynamic radius of its molecules. It is found that an increase in the fraction of maleic acid units in the copolymer from 12 to 42 mol % brings about a reduction in the equilibrium rigidity of its macromolecules from 4.1 to 2.2 nm. The equilibrium rigidity of polyelectrolyte-complex molecules is higher than that of initial copolymer molecules owing to steric interactions arising between the aliphatic chains of dodecyl sulfate anions. In an electric field, the molecules of the complex are oriented owing to the induced dipole moment resulting from the displacement of dodecyl sulfate anions along the chain contour.     

Stability of <Emphasis Type="Italic">s</Emphasis>-, <Emphasis Type="Italic">p</Emphasis>-, and <Emphasis Type="Italic">d</Emphasis>-element diphosphates in water

The mean atomic Gibbs energies of formation of (Δ _f ? _at ⁰ ) of s-, p-, and d-element diphosphates have been calculated using ion increments of the Gibbs energy (Δ _f G ⁰). The diphosphate hydrolysis kinetics is considered, and a correlation between the Δ _f ? _at ⁰ values and the hydrolysis rate constants is presented.     

Inhibitory Effect of Biosynthesized Silver Nanoparticles from Extract of <Emphasis Type="Italic">Nitzschia palea</Emphasis> Against Curli-Mediated Biofilm of <Emphasis Type="Italic">Escherichia coli</Emphasis>

Extended spectrum beta lactamase (ESBL) are emerging beta-lactamases in Gram-negative pathogens, causing serious problems in hospitalized patients worldwide. Biofilm mode of virulence has decreased the efficiency of antibiotics used for treatment against ESBL pathogens. Therefore, there is an urgent need for alternative agents such as nanoparticles that can prevent and inhibit the biofilm formation. The aim of the present study was to inhibit the biofilm formed by ESBL-producing Escherichia coli using silver nanoparticles (AgNPs) synthesized with fresh water diatom (Nitzschia palea). AgNPs were characterized using UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDX), and XRD. AgNPs at their biofilm inhibitory concentration (BIC) of 300 ng ml^?1 significantly reduced the biofilm formed by E. coli. Interestingly, Congo red assay revealed the reduction of curli, essential for biofilm formation in the presence of AgNPs. Light and CLSM examination of the biofilm images also validated that in the presence of AgNPs, the biofilm architecture was disintegrated and the thickness was significantly reduced. Overall, the present study exemplifies the use of AgNPs as a plausible alternative for conventional coating agents on implant devices to prevent and control biofilm-associated urinary tract infections.     

Biologically active compounds from <Emphasis Type="Italic">Limonium Gmelinii</Emphasis> and <Emphasis Type="Italic">L. Popovii</Emphasis> I

Compositions of ethylacetate fractions of roots and aerial parts of Limonium Gmelinii and L. Popovii (Plumbaginaceae) were studied. 3,5,7,3′,4′,6′-Hexahydroxyflavone and myricetin 3-O-α-L-(2′-galloyl)arabopyranoside, the structures of which were established using chemical transformations and spectral data, were isolated for the first time.     

Copolymer of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-diallyl-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylammonium chloride with maleic acid as drug carrier

A copolymer of N,N-diallyl-N,N-dimethylammonium chloride with maleic acid of constant composition was prepared under the conditions of radical initiation. The possibility of the functionalization of the copolymer with drugs containing amino groups by polymer-analogous transformations was examined. Conditions were found for preparing conjugates of the copolymer with isoniazid. The structures and the quantitative compositions of the conjugates were determined by ¹³С NMR spectroscopy, and the possibility of preparing conjugates with controlled drug content was demonstrated.     

Conformations and properties of <Emphasis Type="Italic">O</Emphasis>-Alkyl-<Emphasis Type="Italic">S</Emphasis>-(2-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dialkylamino)-ethylmethylthiophosphonates

Conformers of the biologically active compounds CH₃P(O)(OR)(SCH₂CH₂NR ₂ ^′ ), where (I) R = i-C₄H₉, R′ = C₂H₅ and (II) R = C₂H₅, R′ = i-C₃H₇, are calculated within the AM1 level of theory. The elongated and twisted forms with maximum and minimum distances between a nitrogen atom and those of a phosphorus tetrahedron, respectively, and bearing a syn and anti oriented alkoxy group relative to a phosphoryl oxygen, are studied. It is found that the differences between the energy, electronic, and geometric parameters of these forms are apparent in differences between their properties, e.g., the ability to participate in complexation and protonation, reactions that to some extent simulate the interaction between a substance and a biological object.     

<Emphasis Type="Italic">E. coli</Emphasis>, <Emphasis Type="Italic">P. aeruginosa</Emphasis>, and <Emphasis Type="Italic">B. cereus</Emphasis> Bacteria Sterilization Using Afterglow of Non-Thermal Plasma at Atmospheric Pressure

We developed and employed a new geometrical structure of dielectric barrier discharge in atmospheric pressure for bacterial broad spectrum sterilization. We utilized a plasma source having an AC power supply at 50 HZ and 5,400 V (rms value). We prepared suspensions of the Gram-negative bacteria species (Escherichia coli, Pseudomonas aeruginosa) and a Gram-positive of Bacillus cereus with Luria–Bertani broth media up to OD_600 nm = 0.25 of McFarland standard. Afterglow of non-thermal atmospheric pressure plasma treated these suspensions. The influence of the atmospheric plasma afterglow on the species was assayed in different time durations 5, 10, and 15 min. The spectroscopic results of this investigation indicated that the survival reduction of the species can reach to 100% for P. aeruginosa in an exposure time of 10 min, E. coli and B. cereus in an exposure time of 15 min.     

<Emphasis Type="Italic">Stachys lavandulifolia</Emphasis> and <Emphasis Type="Italic">Lathyrus</Emphasis> sp. Mediated for Green Synthesis of Silver Nanoparticles and Evaluation Its Antifungal Activity Against <Emphasis Type="Italic">Dothiorella sarmentorum</Emphasis>

In this study, silver nanoparticles (AgNPs) were biosynthesized using Stachys lavandulifolia and Lathyrus sp. The first sign of the reduction of silver ions to AgNPs was the change in color of S. lavandulifolia and Lathyrus sp. extracts changed into dark brown and auburn after treating with silver nitrate, respectively. The UV–Vis spectroscopy of reaction mixture (extract+silver nitrate) produced by S. lavandulifolia and Lathyrus sp. showed the strong adsorption peaks at ?440 and 420 nm, respectively. The transmission electron microscope images showed the synthesis of AgNPs using S. lavandulifolia and Lathyrus sp. with an average size of 7 and 11 nm, respectively. The result of X-ray diffraction pattern showed four diffraction peaks at 38°, 44°, 64°, and 77° for both types of biosynthesized AgNPs. Fourier transform infrared spectroscopy showed the possible role of involved proteins and polyhydroxyl functional groups in the synthesis process of AgNPs. Inductively coupled plasma analysis determined the conversion rate (percentage) of silver ions to silver nanoparticles in reaction mixtures of S. lavandulifolia and Lathyrus sp. 99.73 and 99.67 %, respectively. In addition, antifungal effect of AgNPs, synthesized by both extracts, was studied separately on mycelial growth of Dothiorella sarmentorum, in a completely randomized design on potato dextrose agar (PDA) medium. The inhibition rate of mycelial growth was strongly depended on the density of AgNPs and it strongly increased with increasing the density of AgNPs in the PDA medium. AgNPs more than 90 % of them inhibited from the mycelia growth of the fungus at the concentration of 40 µg/mL and higher.     

Analysis of <Emphasis Type="Italic">Escherichia coli</Emphasis> nicotinate mononucleotide adenylyltransferase mutants <Emphasis Type="Italic">in vivo</Emphasis> and <Emphasis Type="Italic">in vitro</Emphasis>

Background  

Adenylation of nicotinate mononucleotide to nicotinate adenine dinucleotide is the penultimate step in NAD⁺ synthesis. In Escherichia coli, the enzyme nicotinate mononucleotide adenylyltransferase is encoded by the nadD gene. We have earlier made an initial characterization in vivo of two mutant enzymes, NadD72 and NadD74. Strains with either mutation have decreased intracellular levels of NAD⁺, especially for one of the alleles, nadD72.     

A Novel Green Synthesis of Silver Nanoparticles Using <Emphasis Type="Italic">Rubus crataegifolius</Emphasis> Bge Fruit Extract

We report a facile, cost effective, and environmentally friendly green chemistry method for preparing silver nanoparticles (AgNPs) using Rubus crataegifolius bge (RCB) fruit extract. The amount of the fruit extract used was found to be important parameters in the growth of AgNPs. In this study, the effect of RCB fruit extract on the synthesis of AgNPs was studied using UV–Vis spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction (XRD), and dynamic light scattering analyses were performed to characterize the RCB fruit extract-stabilized AgNPs. The formation of the AgNPs was confirmed by the color change of the reaction medium and the absorbance peak observed at 420 nm. The XRD analysis confirmed the face centered cubic structure of the AgNPs. The catalytic property of the as-synthesized AgNPs was analyzed for the reduction of 4-nitrophenol to 4-aminophenol.     

Antioxidant flavonoids from <Emphasis Type="Italic">Tamus communis</Emphasis> ssp. <Emphasis Type="Italic">cretica</Emphasis>

A new flavonoid, kaempferol-3,4′-di-O-α-L-rhamnopyranoside (1), and three known flavonoids (2–4) were isolated from the aerial parts of T. communis L. The structure of the new compound was elucidated on the basis of spectroscopic data. Compounds 1 and 2 showed significant antioxidant activity (IC₅₀ 187.151 ± 0.821 μM, and 92.079±0.513 μM, respectively), whereas compounds 3 and 4 showed moderate activity in DPPH free radical scavenging assays. Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 295–297, May–June, 2009.     

New lignans from <Emphasis Type="Italic">Syringa reticulata</Emphasis> var. <Emphasis Type="Italic">mandshurica</Emphasis>

In the search for platelet-activating-factor (PAF) antagonists, two new lignan compounds were isolated from the leaves of Syringa reticulata Hara var. mandshurica. Their structures were elucidated as (7R,8S, 8'S)-3,4,3',4'-dimethylenedioxy-8,9-dihydroxy-8.8', 7-O-9'-lignan (mandshuricol A) and (7R,8S,8'S)-3',4'methylenedioxy-4-methoxy-3,8,9-trihydroxy-8.8', 7-O-9'-lignan (mandshuricol B), Mandshuricol A and B showed antagonistic activity on PAF in the [³H] PAF receptor binding assay with IC₅₀ values of 4.8 × 10^–5 M and 3.5 × 10^–5 M, respectively.     

Interaction of Fluosilicic Acid with <Emphasis Type="Italic">N-tert</Emphasis>-Butyl-Substituted Urea. Crystal Structure of <Emphasis Type="Italic">N,N</Emphasis>-Di-<Emphasis Type="Italic">tert</Emphasis>-butylurea

Fluosilicic acid reacts with solutions of N,N-di-tert-butylurea (DTBU) in methanol or acetone to form crystalline compounds 2DTBU ? H₂SiF₆ and 2DTBU ? H₂SiF₆ ? Me₂CO, which were characterized by the IR and ¹⁹F NMR spectra and mass spectroscopy supplemented by theoretical calculations. According to the data of IR and ¹⁹F NMR spectra, the complexes are hexafluorosilicates of O-protonated DTBU. They undergo hydrolysis in organic media with water traces; their solubility in water is very low (0.10 and 0.14 wt %, respectively). In the DTBU structure, two independent ligand molecules are joined by hydrogen bonds NH?O(N?O) 2.888(5)–2.944(5) Å).     

Alkaloids of <Emphasis Type="Italic">Arundo donax</Emphasis> L.

The structure of a new dimeric indole alkaloid, arundarine, isolated from the roots of the plant Arundo donax L. (Poaceae) was determined. On the basis of spectroscopic data, arundarine was identified as 5-[3-(2-dimethylaminoethyl)indol-1-yl]-6-hydroxy-N ²-methyl-1,2,3,4-tetrahydro--carboline.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1697–1699, August, 2004.For Part 14, see Ref. 1.     

Synthesis of <Emphasis Type="Italic">N,N</Emphasis>-disubstituted (<Emphasis Type="Italic">Z</Emphasis>)-<Emphasis Type="Italic">O</Emphasis>-methylnicotinamide oximes

A number of (Z)-N,N-dialkyl- and (Z)-N-acyl-N-alkyl-O-methylnicotinamide oximes was synthesized. Their configuration was confirmed by the NOESY experiment. Evaluation of fungicidal activity of compounds obtained was performed.