The Chemical Profiling,Docking Study,and Antimicrobial and Antibiofilm Activities of the Endophytic fungi Aspergillus sp. AP5

Growing data suggest that Aspergillus niger, an endophytic fungus, is a rich source of natural compounds with a wide range of biological properties. This study aimed to examine the antimicrobial and antibiofilm capabilities of the Phragmites australis-derived endophyte against a set of pathogenic bacteria and fungi. The endophytic fungus Aspergillus sp. AP5 was isolated from the leaves of P. australis. The chemical profile of the fungal crude extract was identified by spectroscopic analysis using LC-HRESIMS. The fungal-derived extract was evaluated for its antimicrobial activity towards a set of pathogenic bacterial and fungal strains including Staphylococcus aureus, Pseudomonas aeruginosa, Proteus vulgaris, Klebsiella sp., Candida albicans, and Aspergillus niger. Moreover, antibiofilm activity toward four resistant biofilm-forming bacteria was also evaluated. Additionally, a neural-networking pharmacophore-based visual screening predicted the most probable bioactive compounds in the obtained extract. The AP5-EtOAc extract was found to have potent antibacterial activities against S. aureus, E. coli, and Klebsiella sp., while it exhibited low antibacterial activity toward P. Vulgaris and P. aeruginosa and displayed anticandidal activity. The AP5-EtOAc extract had significant antibiofilm activity in S. aureus, followed by P. aeruginosa. The active metabolites’ antifungal and/or antibacterial activities may be due to targeting the fungal CYP 51 and/or the bacterial Gyr-B.     

System size dependence in backward relativistic hadron production in pA and AA collisions

In this comprehensive study the multiplicity characteristics of the backward emitted relativistic hadron(shower particle) through hadron-nucleus and nucleus-nucleus are overviewed in three dimensions. These dimensions are the projectile size, target size, and energy. To confirm the universality in this production system, wide ranges of system size and energy(Elab ～2.1 A up to 200 A GeV) are used. The multiplicity characteristics of this hadron imply a limiting behavior with respect to the projectile size and energy. The target size is the main effective parameter in this production system. The exponential decay shapes is a characteristic feature of the backward shower particle multiplicity distributions. The decay constant changes with the target size to be nearly 2.02, 1.41, and 1.12 for the interactions with CNO, Em, and Ag Br nuclei, respectively, irrespective of the projectile size and energy. While the backward production probability and average multiplicity are constants at different projectile sizes and energies, they can be correlated with the target size in power law relations.     

Synthesis and antifungal property of N-(aryl) and quaternary N-(aryl) chitosan derivatives against Botrytis cinerea

A series of N-(aryl) and their quaternary N-(aryl) chitosan derivatives were synthesized and evaluated for their antifungal activity against crop-threatening fungus Botrytis cinerea. Schiff bases were firstly synthesized by the reaction of chitosan with cinnamaldehyde, cuminaldehyde and 4-dimethylaminobenzaldehyde followed by reduction with sodium borohydride to form N-(aryl) chitosans. Quaternary N-(aryl) chitosans were then obtained by reaction of N-(aryl) chitosan compounds with ethyl iodide. The chemical structures were characterized by ¹H-NMR, FT-IR and UV spectroscopic techniques. The antifungal activity was evaluated in vitro against B. cinerea by mycelial growth inhibition method and in vivo by application of compounds to tomato plants prior to inoculation with fungal spores. In an in vitro experiment, all quaternized chitosans were more active than N-(aryl) chitosan derivatives and N,N,N-(diethylcinnamyl) chitosan (QC1) was the most potent (EC₅₀ = 1,147 mg/L) against mecelia however, N,N,N-(diethyl-p-dimethylaminobenzyl) chitosan (QC3) was the most potent (EC₅₀ = 334 mg/L) against spores. In an in vivo study, no disease incidence (0.0 %) was observed with QC1 and QC3 at 1,000 mg/L. Spray liquid chitosan enhanced total phenolics and guaiacol peroxidase in inoculated leaves.     

Determination of secnidazole in tablets and human serum by cathodic adsorptive stripping voltammetry

The electrochemical reduction of secnidazole was carried out in BR buffer solutions in the pH range 2.0–11.8 by dc polarography. The polarograms exhibited two irreversible reduction waves in acidic media and one wave in alkaline media, corresponding to the reduction of nitro group in the drug. The cathodic adsorptive voltammetric behavior was studied on glassy carbon electrode to optimize an analytical method for determination of secnidazole. The drug was determined in the range between 4.0 × 10^?6 and 1.2 × 10^?4 mol L^?1. The proposed method was successfully applied to the determination of the drug content in tablets with mean recovery and relative standard deviation of 100.91% and 1.82%, respectively. It was also applied to human serum with a good precision and accuracy.     

Chemoselective Bromination in a Two-Step Substitution Under the Influence of Tetrachlorosilane and N-Bromosuccinimide

The synthesis of gem dibromide carbonyl compounds via a cheep and readily available combined reagent from tetrachlorosilane and N-bromosuccinimide (TCS-NBS).     

Effect of CeO2-doping on surface and catalytic properties of CuO-ZnO system

The effect of doping CuO-ZnO system with CeO₂ on its surface and catalytic properties was investigated using nitrogen adsorption at −196 °C, EDX technique and catalysis of CO oxidation by O₂ at 100-200 °C. Pure mixed solids were prepared by thermal decomposition of copper/zinc mixed hydroxides at 400 °C. The doped solids were obtained by impregnating a known mass of mixed hydroxides with calculated amount of cerium ammonium nitrate followed by drying then calcination at 400 °C. The dopant concentration was 1.5, 3.0 and 4.5 mol% CeO₂. The results revealed that CeO₂-doping modified the surface atomic Cu/Zn ratio of the system investigated and changed the crystallite size of both CuO and ZnO phases. The increase of the amount of dopant added changed the major phase present. This treatment decreased the specific surface area of doped solids. The doping process modified also the catalytic activity in a manner dependent on both mode of preparation and dopant concentration. However, CeO₂-doping did not modify the mechanism of the catalytic reaction but changed the concentration of catalytically active sites involved in the catalyzed reactions.     

Chemistry of quinazolines: Reinvestigation of the action of hydrazine on thioxo derivatives

The action of hydrazine on 2-mercapto and 2-alkylmercaptoquinazolin-4-ones is reinvestigated. The structure of the isolated products have been revised.     

Studies on halogen derivatives of phenylazochromotropic acid: II. Spectrophotometric microdetermination of thorium

A new rapid and accurate method for the spectrophotometric microdetermination of thorium using o, p-dichloro-, p-bromo-, and p-iodophenylazochromotropic acids is given. The optimum conditions favoring the formation of the complexes are extensively investigated. The molecular structure was found to be 1:1 and 1:2 Beer's law is obeyed up to 16.24, 18.56, and 11.60 ppm of Th using the three reagents, respectively.     

The role of the interfacial SiOx layer in SnO2/n-Si photocells

It is proposed that the charge transport across the SiO _x layer at the interface SnO₂/Si proceeds by a hopping mechanism. During heat treatment of the photovoltaic cells, in air, chemical reactions occur with O₂/H₂O, which lead to a drastic reduction of the density of hopping sites near the Si conduction band edge. The SiO _x hopping sites of energy near the valence band edge are less affected by these chemical reactions. Thus, photogenerated holes can still pass the barrier while the dark current flow is strongly inhibited.     

Synthesis and structure of 6- and 7-(2-arylvinyl)pteridines

7-Hydroxy-6-styrylpteridine 9 and 7-(2-arylvinyl)-6-hydroxypteridines 10–12 were synthesized via the condensation of 5,6-diaminouracil 1 with benzylidenepyruvic acids 2–4 . The synthesis of the 2-methylthio analogue 15 is also described.