In Vitro Antibacterial Activity of Green Synthesized Silver Nanoparticles Using Azadirachta indica Aqueous Leaf Extract against MDR Pathogens

Rice is the most important staple food crop feeding more than 50% of the world’s population. Rice blast is the most devastating fungal disease, caused by Magnaporthe oryzae (M. oryzae) which is widespread in rice growing fields causing a significant reduction in the yield. The present study was initiated to evaluate the effect of green synthesized silver nanoparticles (AgNPs) on the biochemical constituents of rice plants infected with blast. AgNPs were synthesized by using Azadirachta indica leaf extract and their characterization was performed using UV-visible spectroscopy, particle size analyser (PSA), scanning electron microscope (SEM), and X-ray diffraction (XRD) which confirmed the presence of crystalline, spherical shaped silver nanoparticles with an average size of 58.9 nm. After 45 days of sowing, artificial inoculation of rice blast disease was performed. After the onset of disease symptoms, the plants were treated with AgNPs with different concentrations. Application of nanoparticles elevated the activity of antioxidative enzymes such as superoxide dismutase, catalase, peroxidase, glutathione reductase, and phenylalanine ammonia-lyase compared to control plants, and total phenol and reducing sugars were also elevated. The outcome of this study showed that an increase in all biochemical constituents was recorded for A. indica silver nanoparticles-treated plants. The highest values were recorded in 30 ppm and 50 ppm AgNPs-treated plants, which showed the highest resistance towards the pathogen. Green synthesized AgNPs can be used in future for disease control in susceptible varieties of rice. The synthesized AgNPs using A. indica leaf extract have shown promising antibacterial activity when tested against 14 multidrug-resistant (MDR) bacteria comprising Gram-negative bacteria Escherichia coli (n = 6) and Klebsiella pneumoniae (n = 7) with a good zone of inhibition diameter, tested with the disc diffusion method. Based on these findings, it appears that A. indica AgNPs have promise as an antibacterial agent effective against MDR pathogens.     

Interaction of an Endosomolytic Polyamidoamine ISA23 with Vesicles Mimicking Intracellular Membranes: A SANS/EPR Study

The mechanism of ISA23 · HCl interaction with model membrane vesicles (80–100 nm in diameter) was investigated using EPR in conjunction with SANS. For EPR, 16‐DSE was dissolved in the vesicle membrane to measure its dynamics and polarity, whereas a spin‐labeled (Tempo)‐ISA 23 analogue was used to give a measure of the polymer flexibility. When ISA23 was added to the external vesicle surface, no interaction was found. This observation conflicts with the reported ability to lyse RBC, but is in agreement with recent studies that showed no effect on membrane permeability when a PAA was added to an incubation medium containing isolated lysosomal vesicles. The vesicle‐mimetic models used here provide a new and useful tool for studying endosomolytic polymer/membrane interactions.

     

Ethanol-induced changes in glycolipids of Saccharomyces cerevisiae

Total glycolipid content of Saccharomyces cerevisiae cells increased in ethanol-treated yeast cells. Sialic acid and hexosamine contents of glycolipids from ethanol-treated cells decreased, whereas those of hexoses increased. Increased sialidase activity in the presence of ethanol may be responsible for the decrease in sialic acid content of glycolipids. The saccharide moieties of glycolipids of S. cerevisiae consisted of fucose, mannose, galactose, and glucose. Ethanol treatment of yeast cells caused an increase in glucose and a decrease in galactose content of glycolipids. The changes in glucose content can be related to changes in β-glucosidase activity under alcohol stress. The content of cerebrosides, sulfatides, and monoglucosyldiglycerides was enhanced following ethanol treatment. An increase in cerebroside as well as in sulfatide content during alcohol stress might play an important role in stabilizing the membrane both physically and structurally. Such variations in glycolipid content and composition of S. cerevisiae cells may represent an adaptive response to ethanol stress.     

Mucoadhesive vaginal film of fluconazole using cross-linked chitosan and pectin

A series of silica gels (Si-40, Si-60, Si-100) and related carbon–silica gels, prepared by carbonization of CH₂Cl₂ at a surface of silica gels at 550 °C, characterized using FTIR/PAS, SEM/EDX, and nitrogen adsorption, was investigated upon interactions with polar (water, dimethylsulfoxide), weakly polar (chloroform), and nonpolar (n-hexane, n-decane, benzene, toluene) adsorbates using adsorption and differential scanning calorimetry methods. Features of confined space effects, such as freezing/melting point depression and melting delay, depend strongly on pore sizes, pore wall structure, type and amount of adsorbates, and the degree of pore filling. Melting curves of both polar and nonpolar adsorbates bound in broad pores (Si-60 and Si-100 based materials) can include two–three peaks around melting point, but for Si-40-based materials, a number of similar peaks is smaller. This occurs due to step-by-step melting of frozen structures located in broader pores and the absence of similar effects in narrower pores. The present study shows that complex carbon–silica gel adsorbents can be more effective adsorbents than simple silica gels due to the presence of a number of surface sites of various polarity and structure.

     

Optimization of Fiber-Water Dispersion Process Using Box-Behnken Design of Experiments Coupled with Response Surface Methodology of Analysis

In this work, the fiber-water dispersion process with reference to the wet-lay technology was optimized in order to improve the uniformity of the wet-laid webs by using Box-Behnken design of experiments coupled with response surface methodology of analysis. A series of wet-laid webs were prepared by using cotton fibers of 7 mm cut length and 5.6 micronaire linear density and employing different combinations of three process variables of interest namely stirring rate, dispersion time, and surfactant concentration. The resulting webs were tested for their area-based uniformity by means of quadrat analysis. The response surface model was found to be statistically significant at a P value as low as 0.0213. The experimental results were found to be in good agreement with the model results. The single effect of surfactant concentration, interaction effect of surfactant concentration and stirring rate, and quadratic effect of dispersion time were found to be statistically significant at 0.05 level of significance. The optimum level of coefficient of variation of the area occupied by the fibers in the web was predicted as 10.50% at stirring rate of 250 rpm, dispersion time of 5 minutes, and surfactant concentration of 0.10 and this was experimentally observed as 11.02%.     

Low level Pu and Am estimation in liquid waste from nuclear reactor

Estimation of very low amount up to pico-gram of Am and Pu in the liquid waste of U–Pu fuel cycle of the irradiated U fuel from the nuclear reactor has been carried out using combined method of α- and γ-ray spectrometric techniques. ²⁴¹Am was estimated by γ-ray spectrometry from a plancheted source. In spite of the same α energy of 5.49 MeV for ²⁴¹Am and ²³⁸Pu, the amount ²³⁸Pu was estimated by α spectrometry from the same plancheted source after subtracting amount of the ²⁴¹Am obtained from γ-ray spectrometry. The amount of Am and Pu obtained by this technique is found to be superior compared to other techniques even in the presence of Th, U and fission products.     

Possible intermolecular association in triphenyltin chloride in the solution state as detected by NMR spectroscopy

NMR measurements ((119)Sn chemical shift, line width and (13)C relaxation) were made on triphenyltin chloride in two solutions, 2.5 and 0.75 mol% in CDCl(3), at several temperatures. The (13)C spin-lattice relaxation time and NOE data for the phenyl carbons provide the corresponding correlation times for the overall molecular reorientational motion and the internal rotation of the phenyl groups. The results are indicative of a weak intermolecular association of the triphenyltin chloride molecules in solution and are discussed with reference to a model for intermolecular phenyl ring π-π stacking interactions.     

One-Pot Green Synthesis of 3'-(2-Aminobenzimidazolyl)-2-Phenyl Spiro[4H-Benzopyran-4,2'-Thiazolidin]-4-Ones and Acylation Using Trifluoroacetic Anhydride

Abstract

An expeditious one-pot synthesis of a novel heterocyclic system, 3′-(2-aminobenzimidazolyl)-2-phenyl spiro[4H-benzopyran-4,2′-thiazolidin]-4-ones, has been accomplished by condensing substituted hydrazinobenzimidazole, flavanone, and mercaptoacetic acid by conventional heating in ethanol or toluene, and in an ionic liquid, viz., 1-butyl-3-methyl-imidazolium hexafluorophosphate. Excellent yields (85%–90%) and higher purity are obtained in the ionic-liquid-mediated synthesis as compared with the conventional procedure (55%–60%). Further, these compounds were acylated with trifluoroacetic anhydride. The structures of the compounds were confirmed by IR, ¹H NMR, ¹³C NMR, mass spectral data, and elemental analysis. The compounds, upon evaluation for their antibacterial, antifungal, and insecticidal activities, exhibited excellent results.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Table S1, S2, and S3]

GRAPHICAL ABSTRACT