Induced secondary metabolites from the endophytic fungus Aspergillus versicolor through bacterial co-culture and OSMAC approaches

Two new cryptic 3,4-dihydronaphthalen-(2H)-1-one (1-tetralone) derivatives, aspvanicin A (1) and its epimer aspvanicin B (2), as well as several known cryptic metabolites (3–8), were obtained from the ethyl acetate extract of the co-culture of the endophytic fungus Aspergillus versicolor KU258497 with the bacterium Bacillus subtilis 168 trpC2 on solid rice medium. When A. versicolor was cultured axenically in liquid Wickerham medium supplemented with 3.5% DMSO, an additional three known secondary metabolites (9–11) were isolated that were lacking when the fungus was fermented on rice medium. The structures of the new compounds were elucidated using one- and two-dimensional NMR spectroscopy as well as HRESIMS. The relative and absolute configurations of 1 and 2 were determined by the combination of NMR and electronic circular dichroism (ECD) analysis aided by DFT conformational analysis and TDDFT-ECD calculations. The ECD calculations revealed that although the sign of the blue-shifted overlapping n-π¹ ECD transition follows the helicity rule of cyclic aryl ketones, the calculation of low-energy conformers and ECD spectra was necessary to determine the stereochemistry. All metabolites were assessed for their antibacterial and cytotoxic activities; one of the new diastereomers, compound 2, showed moderate cytotoxic activity against the mouse lymphoma cell line L5178Y.     

Sonication-assisted preparation of a nanocomposite consisting of reduced graphene oxide and CdSe quantum dots,and its application to simultaneous voltammetric determination of ascorbic acid,dopamine and uric acid

Microchimica Acta - Accurate detection of temperature and oxygen concentration at the cellular level is important in tumor diagnosis. Multifunctional nanocomposites are described that consist of...     

Synthesis and structural characterization for novel mixed-donor ligand palladium (II) based on graphene and oxime: its application as a highly stable and efficient recyclable catalyst

In this article, the palladium (II) mixed-ligand complex synthesized with reduced graphene oxides containing tetraethoxysilane and menthone oxime was used as an efficient solid catalyst for the Heck coupling reaction. To maintain stability and catalytic activity in the C–C bond reaction, graphene was considered due to the available surface as the solid support. Then, the structure of new heterogeneous catalyst was investigated by FT-IR, UV–Vis DRS, FE-SEM, EDX, AFM, XRD, ICP-OES, Raman, and TGA. The newly synthesized nanocatalyst have beneficial properties, including product’s easy separation, the shorter time to react, purity products (yield 79–99%), and easier work-up procedure. Furthermore, the catalyst was reused six times without significant degradation in catalytic activity and performance.     

Experimental determination of acetamiprid pesticide residue in three different types of pistachio by ion mobility spectrometry and using QuEChERS method in the different temperatures and in the presence of ammonia as dopant gas

In this project, Ion Mobility Spectrometer (IMS) instrument in the positive mode and with corona ionization source was utilized to determine the residue of acetamiprid pesticide in three different types of pistachio (Akbari, Fandoghi and Kalachuchi). The QuEChERS method, notable because of easy and quick preparation of sample and using lower amounts of organic solvents with harmful environmental effects and high costs, was used in this study. Many experiments were performed in the different temperatures in order to obtain optimum temperature for cell and injection. Ammonia and acetone were considered as dopant substances and it turned out that the ammonia gas, contrary to acetone, increased significantly the signal intensity and sensitivity and avoided the overlap of desired peaks. The LOD of device for acetamiprid pesticide was estimated to be 0.5 μg g^?1 and the LOQ of instrument was obtained as 1.66 μg g^?1. The calibration curve was in the dynamic range between 0.5–11.5 μg g^?1 and the Correlation Coefficient was 0.998. Also, the ion mobility and the reduced ion mobility were calculated for acetamiprid ion. After analysis of five samples with IMS instrument, the acetamiprid residue was determined and it turned out that it was under allowed limit in all three types of pistachio. In addition, the amount of acetamiprid residue was higher for Akbari type relative to Fandoghi and Kalachuchi ones. The reason for this observation is the higher vulnerability of Akbari trees to insects and pests and this in turn causes more pesticide to be consumed.     

Preparation and evaluation of polymer-coated adsorbents for the expanded bed recovery of protein products from particulate feedstocks

A novel prototype polymer-coated adsorbent (PCA) has been developed for the effective expanded bed recovery of protein products from particulate feedstocks. The adsorbents were manufactured using the three-phase emulsification process by which the selected core phases (anion- and cation-exchangers and a custom-assembled pseudo-affinity adsorbent) were coated by an agarose gel. This new non-stick exterior coating acts as a sieve reducing the non-specific binding of cell and cell debris without diminution of selective capture of target protein from complex feedstocks such as whole microbial broths and cell disruptates. The new coated adsorbents were subjected to physical and hydrodynamical comparison with the performance of their uncoated adsorbents. Hydrodynamic characteristics (e.g. axial dispersion coefficient (D(axl)) and Bodenstein number (B(o))) of PCA demonstrated a marked robustness in the face of biomass loading disrupted yeast cells. In addition, each adsorbent was compared with its uncoated native form during the expanded bed adsorption of one of two intracellular proteins (i.e. glyceraldehyde 3-phosphate dehydrogenase and cytochrome c) from a 20% (ww/v) yeast disruptate. The performance parameters of efficiency of washing, purification factor, turbidity of the eluted product and protein recovery in all analysed cases were favourable to the coated materials. In particular, exploiting PCA reduced significantly undesirable adsorption of cells without significant loss of binding capacity for the target product. The generic application of such adsorbents and their potential for the recovery of target products from complex feedstock is discussed, whilst other application such as the subtractive purification of nanoparticles were detailed in our previous publication.     

Practical reduction of imines by NaBH4/alumina under solvent-free conditions： An efficient route to secondary amine

Sodium borohydride supported on alumina reduces imines to the corresponding secondary amines in high to excellent isolated yields under solvent-free conditions. Noteworthy is that highly chemoselective reactions were achieved in the presence of other functional groups such as halogen, nitro, and cyano groups.     

Target‐Induced and Equipment‐Free DNA Amplification with a Simple Paper Device

We report on a paper device capable of carrying out target‐induced rolling circle amplification (RCA) to produce massive DNA amplicons that can be easily visualized. Interestingly, we observed that RCA was more proficient on paper than in solution, which we attribute to a significantly higher localized concentration of immobilized DNA. Furthermore, we have successfully engineered a fully functional paper device for sensitive DNA or microRNA detection via printing of all RCA‐enabling molecules within a polymeric sugar film formed from pullulan, which was integrated with the paper device. This encapsulation not only stabilizes the entrapped reagents at room temperature but also enables colorimetric bioassays with minimal steps.     

Environmentally benign and highly regioselective ring opening of epoxides accelerated by ultrasound irradiation

Regioselective ring opening of aliphatic and aromatic epoxides with nitrogen heterocycles such as indoles and imidazoles was accelerated using an ultrasonic technique as a green approach. An optimized procedure with the catalyst of choice, MCM-41, represents a real alternative to the conventional reaction protocols owing to the catalyst recyclability, simplicity, green conditions and time-saving aspects.