Microwave-assisted rapid and efficient synthesis of chromene-fused pyrrole derivatives through multicomponent reaction and evaluation of antibacterial activity with molecular docking investigation

The current study aimed to identify a new strategy of FeCl₃ catalyzed multicomponent synthesis of substituted 2H-chromene–fused pyrrole derivatives. A series of chromene-based pyrrole prepared by employing an array of 3-nitro-2H-chromenes, aniline, and acetylacetone in toluene under microwave irradiation. Using FeCl₃ as a prompt catalyst and microwave irradiation to synthesize 2H-chromene–fused pyrrole motifs significantly reduces the reaction time and facilitates to high yields (83%-95%). Structure of all synthesized compounds analyzed by spectroscopic analysis. One-pot reaction, short reaction period, and simple experimental procedure are the fascinating properties associated with this protocol. The in vitro antibacterial activity of the entire series was assessed against Staphylococcus aureus and Escherichia coli. Out of all the compounds, 15b and 15h revealed most excellent potency against both the bacterial strains relative to the reference gentamicin. Docking study was employed to determine the possible binding orientation of DNA gyrase with the active sites of chromene-fused pyrrole analog. The docking results show that compounds 15b and 15h have higher binding affinity with energy −8.00 and −8.80 kcal/mol. These results illuminate the mode of binding progression and provide an esteemed pathway for the design and the structural modification of chromene-fused pyrroles as a newly advanced class of antibacterial agent.     

RAPD and ISSR Marker-Based Comparative Evaluation of Genetic Diversity Among Indian Germplasms of <Emphasis Type="Italic">Euryale ferox</Emphasis>: an Aquatic Food Plant

Euryale ferox Salisbury is an important aquatic food plant cultivated largely in eastern India. E. ferox is a monotypic genus, and breeding programmes have mostly relied on the variability present in the primary gene pool. Knowledge of the genetic structure of the population is limited, and there are very few reports available on the genetic diversity of E. ferox. In this study, comprehensive research on the genetic diversity of 16 germplasms of E. ferox was carried out using random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers. Out of 320 RAPD and 95 ISSR primers screened initially, 61 primers (40 RAPD and 21 ISSR) gave reproducible bands and were selected for further work. Amplification of the 40 RAPD primers gave 533 polymorphic bands with an average of 13.32 polymorphic bands per primer. The percentage of polymorphism ranged from 37.5 to 100, with an average of 88.3 %. The 21 ISSR primers produced 259 bands, of which 214 were polymorphic, with an average of 10.19 polymorphic bands per primer. The percentage of polymorphism using ISSR primers ranged from 50 to 100, with a mean of 82.6 %. Jaccard’s coefficient ranged from 0.45 to 0.69 (RAPD), 0.50 to 0.77 (ISSR) and 0.48 to 0.71 (RAPD and ISSR). Molecular characterization of different germplasms of E. ferox not only is essential for its conservation but also can be used in further breeding programmes.     

Acoustical and thermodynamical parameters of aluminium oxide nanoparticles dispersed in aqueous ethylene glycol

In the present work aluminium oxide (Al₂O₃) nanoparticles were synthesised by the precipitation method using AlCl₃ as a starting material. The synthesised nanoparticles were characterised by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). These nanoparticles have been dispersed in base fluid, an aqueous solution of ethylene glycol (EG). Density (ρ), ultrasonic velocity (u), and viscosity (η) for these nanofluids have been measured at different concentrations as a function of temperature (T = 303.15 K, 308.15 K, and 313.15 K). Using their values various acoustical and thermodynamical parameters have been computed.     

Preparation and characterization of cyclodextrin complexes of doxycycline hyclate for improved photostability in aqueous solution

Doxycycline hyclate is Biopharmaceutical Classification System, class I drug (high solubility and high permeability), but it is associated with poor photostability. It is in the class of tetracycline antibiotic, which is used to treat various infections, but its bioavailability is compromised due to its sensitivity to light and aqueous instability. In this paper, the influence of inclusion complexation with different cyclodextrins, i.e., αCD, γCD, HPβCD and RMβCD, on the photostability of doxycycline hyclate in aqueous media was investigated. Host–guest inclusion complexes were prepared by freeze- drying method. The prepared complexes were characterized for drug content, SEM, XRPD, in vitro permeation studies and photostability studies. XRPD showed diffused peaks for most of the complexes, while SEM showed irregularly shaped particles. The formulation D20 (Drug: γCD in 1:20 molar ratio) showed the highest % drug content (83.72?±?1.2%), and the formulations D1 (Drug: αCD in 1: 2 molar ratio) showed the lowest % drug content among all the CD complexes. It was found that the photodegradation of the drug was reduced significantly upon complexation. For Drug: CD complexes, the photostability of the aqueous solution of drug/CD complexes was found to be in the order of γCD?>?RMβCD?>?HPβCD?>?αCD with maximum photostability shown by Drug: γCD (1:20 molar ratio) complex. The obtained results suggested that cyclodextrin complexation can be used as an alternative approach for increasing the photostability of doxycycline hyclate.

     

Fenchone Derivatives as a Novel Class of CB2 Selective Ligands: Design,Synthesis, X-ray Structure and Therapeutic Potential

A series of novel cannabinoid-type derivatives were synthesized by the coupling of (1S,4R)-(+) and (1R,4S)-(−)-fenchones with various resorcinols/phenols. The fenchone-resorcinol derivatives were fluorinated using Selectfluor and demethylated using sodium ethanethiolate in dimethylformamide (DMF). The absolute configurations of four compounds were determined by X-ray single crystal diffraction. The fenchone-resorcinol analogs possessed high affinity and selectivity for the CB2 cannabinoid receptor. One of the analogues synthesized, 2-(2′,6′-dimethoxy-4′-(2″-methyloctan-2″-yl)phenyl)-1,3,3-trimethylbicyclo[2.2.1]heptan-2-ol (1d), had a high affinity (K_i = 3.51 nM) and selectivity for the human CB2 receptor (hCB2). In the [³⁵S]GTPγS binding assay, our lead compound was found to be a highly potent and efficacious hCB2 receptor agonist (EC₅₀ = 2.59 nM, E_(max) = 89.6%). Two of the fenchone derivatives were found to possess anti-inflammatory and analgesic properties. Molecular-modeling studies elucidated the binding interactions of 1d within the CB2 binding site.     

Studying Spatial Distributions of Influenza Hemagglutinin on the Plasma Membrane of Fibroblasts: A Work in Progress

The major envelope protein of influenza virus, hemagglutinin (HA), mediates the fusion of virus to cell for infection, and can mediate cell-cell fusion. It has been studied as a “raft” protein, as it is found in detergent-resistant membranes (DRM) and trafficks apically in polarized epithelia. Moreover, the viral envelope of influenza itself is rich in sphingomyelin and cholesterol. Using both immunogold electron microscopy and fluorescence resonance energy transfer (FRET) microscopy, we are examining the distribution of HA on the surface of fibroblasts expressing wild-type HA.     

Photoacoustic spectroscopic studies of Ho3+, Er3+, and Sm3+ doped polyvinyl alcohol films

Photoacoustic (PA) spectra of Ho³⁺, Er³⁺, and Sm³⁺ doped PVA films were obtained in 350–800 nm range. PA spectra were also obtained for the respective dopant oxides: Ho₂O₃, Er₂O₃, and Sm₂O₃ for comparison. It was found that in PVA the PA sensitivity has increased considerably compared to pure rare earth oxides. The relative intensities of absorption bands at 540 and 637 nm of Ho₃₊: PVA have shown distinct enhancement, indicating the increase in nonradiative relaxation at these excitations. Furthermore, the PA signals at wavelengths for different PA absorption bands were monitored as a function of chopping frequency. These experiments have shown that PA signal varies w⁻¹ both for oxides and PVA samples, suggesting that they behave as thermally thin samples. © 1997 John Wiley & Sons, Inc.     

Synthesis of 5,6- and 5,7-dichloro-3-methyl-4H-1,4-benzothiazines and their conversion into sulfones

A one pot synthesis of 5,6- and 5,7-dichloro-3-methyl-4H,4-benzothiazines is reported by the condensation and oxidative cyclization of 2-amino-3,4- and 3,5-dichlorobenzenethiols with β-dicarbonyl compounds. The oxidation of 4H-1,4-benzothiazines by 30% hydrogen peroxide in glacial acetic acid has provided the corresponding sulfones. The effect of the conversion of the sulfide linkage to sulfone is discussed. The structure of all the newly synthesized compounds has been confirmed by elemental analysis and spectral studies.     

Ammonia gas sensor based on SnO2 nanostructure with the enhanced sensing capability at low temperatures

ABSTRACT

We investigated the gas-sensing performance of tin oxide nanowires for ammonia gas at low temperature (～ 50°C). Tin oxide nanostructures were deposited at 1000°C and 1100°C on gold-coated silicon substrates using the physical vapor deposition method. Gas-sensing measurements were made for ammonia gas at various strengths (i.e. 50, 100 and 200?ppm) and the sensing performance was compared at low temperature for both the samples e.g. nanostructures deposited at 1000°C and 1100°C. Due to the highly oriented structure, the sample deposited at 1000°C shows high sensing capability at low temperature as compared to the regular tetragonal phase observed at 1100°C. The morphological and structural properties of nanowires were systematically examined using the scanning electron microscopy and X-ray diffraction.