A new eco-friendly strategy for the synthesis of novel antimicrobial spiro-oxindole derivatives via supramolecular catalysis

Novel spiro-oxindole derivatives were synthesised by one-pot multicomponent reaction using isatins, urea and 1,3-dicarbonyls. β-Cyclodextrin, an oligosaccharide, catalysed the reaction and can be reused for further reaction after recovery. This developed synthetic route is environmentally benign in which water is used as solvent to produce excellent yields of products. The synthesised compounds were evaluated for their antimicrobial activities against two bacteria and two fungi. All the synthesised spiro-oxindoles exhibit significant antimicrobial activity.     

Studies directed toward the synthesis of caylobolide A: convergent synthesis of C21–C40 subunit

Stereoselective synthesis of the C21–C40 core segment of caylobolide A has been achieved following a highly efficient convergent strategy. The key reactions featured in the synthesis are Prins cyclization, reductive radical cyclization, Sharpless asymmetric epoxidation and olefin cross metathesis.     

Highly regioselective C4-hydrazinylation of 2,4-dichloroquinolines: expedient synthesis of aminoquinoline substituted pyrrolidin-2,5-diones via hydrazinylquinolines

A new class of hydrazinylquinoline regio-isomers has been synthesized through S_NAr reaction of 2,4-dichloroquinolines with hydrazine hydrate. The reaction stops at the mono-substitution product with high regioselectivity at the C₄ rather than C₂ position of dichloroquinolines. The hydrazinylquinolines were subsequently converted into aminoquinoline substituted pyrrolidin-2,5-diones in the presence of Eaton’s reagent.     

Time-delay-induced phase-transition to synchrony in coupled bursting neurons

Signal transmission time delays in a network of nonlinear oscillators are known to be responsible for a variety of interesting dynamic behaviors including phase-flip transitions leading to synchrony or out of synchrony. Here, we uncover that phase-flip transitions are general phenomena and can occur in a network of coupled bursting neurons with a variety of coupling types. The transitions are marked by nonlinear changes in both temporal and phase-space characteristics of the coupled system. We demonstrate these phase-transitions with Hindmarsh-Rose and Leech-Heart interneuron models and discuss the implications of these results in understanding collective dynamics of bursting neurons in the brain.     

Estimation of effective Debye temperature from sound velocity of N-(p-n-alkoxybenzylidene)-p-n-alkylanilines, (nO.m) liquid crystalline compounds

The ratio of specific heats (γ), Poisson's ratio (σ), effective Debye temperature (θ_D) collision factor (S_m), etc., are estimated in different LC phases of N-(p-n-alkoxybenzylidene)-p-n-alkylanilines, (nO.m's) liquid crystalline compounds using the density and sound velocity data. The variation of these parameters in different mesomorphic phases with the chain length is studied. The effective Debye temperature (θ_D), the collision factor (S_m) exhibits a similar variation with the alkyl chain length. Further, the space filling factor (r_fm) estimated using Kittel's formula is constant for all the materials irrespective of the phase with a value of 0.416. The molecular radius shows an increment of 0.074, 0.072 and 0.068 ? per CH₂ group in isotropic, nematic and smectic-A phases respectively in 5O.m series. Further, the specific heat ratio (γ) value is found to be lower in isotropic phase than in liquid crystalline phases. The data is compared with the body of the data in the literature.     

Simulation and experimental studies of a vibro-impact capsule system driven by an external magnetic field

This paper studies the electromagnetic field used for driving a vibro-impact capsule prototype for small bowel endoscopy. Mathematical models of the electromagnetic field and the capsule system are introduced, and analytical solution of the magnetic force applied on the capsule is derived and verified by experiment. The impact force between the inner mass of the capsule and the capsule body is also compared via numerical simulation and experimental testing. By comparing the capsule’s progressions under different control parameters (e.g. the excitation frequency and duty cycle), the merits of using the vibro-impact propulsion are revealed. Based on the experimental results, the optimised speed of the prototype can achieve up to 3.85 mm/s. It is therefore that the potential feasibility of using the external electromagnetic field for propelling the vibro-impact capsule system is validated.

     

Defining the Role of Isoeugenol from Ocimum tenuiflorum against Diabetes Mellitus-Linked Alzheimer’s Disease through Network Pharmacology and Computational Methods

The present study involves the integrated network pharmacology and phytoinformatics-based investigation of phytocompounds from Ocimum tenuiflorum against diabetes mellitus-linked Alzheimer’s disease. It aims to investigate the mechanism of the Ocimum tenuiflorum phytocompounds in the amelioration of diabetes mellitus-linked Alzheimer’s disease through network pharmacology, druglikeness and pharmacokinetics, molecular docking simulations, GO analysis, molecular dynamics simulations, and binding free energy analyses. A total of 14 predicted genes of the 26 orally bioactive compounds were identified. Among these 14 genes, GAPDH and AKT1 were the most significant. The network analysis revealed the AGE-RAGE signaling pathway to be a prominent pathway linked to GAPDH with 50.53% probability. Upon the molecular docking simulation with GAPDH, isoeugenol was found to possess the most significant binding affinity (−6.0 kcal/mol). The molecular dynamics simulation and binding free energy calculation results also predicted that isoeugenol forms a stable protein–ligand complex with GAPDH, where the phytocompound is predicted to chiefly use van der Waal’s binding energy (−159.277 kj/mol). On the basis of these results, it can be concluded that isoeugenol from Ocimum tenuiflorum could be taken for further in vitro and in vivo analysis, targeting GAPDH inhibition for the amelioration of diabetes mellitus-linked Alzheimer’s disease.     

Thermally Stimulated Luminescence in ZnSe:Ag and ZnSe:(Ag,Gd) Phosphors

With a view to understanding the luminescence mechanism in ZnSe, a systematic study of thermally stimulated luminescence (TSL) of UV ray (3650 Å) irradiated ZnSe:Ag and ZnSe:(Ag, Gd) phosphors has been undertaken. TSL glow curves of these phosphors are recorded in the temperature range 110–340 K. The TSL parameters like trap depth, frequency factor, order of kinetics, and capture cross-section of the glow peaks are evaluated employing Cutie's method, various heating method, and peak shape method.     

1-Butyl-3-methylimidazolium Tetrafluoroborate ([BMIM]BF4): An Efficient Ionic Liquid Medium for the Synthesis of Novel 2-(Oxazolo[5,4-b]pyridin-2-yl)-N-phenylbenzamides

Russian Journal of Organic Chemistry - A series of novel 2-(oxazolo[5,4-b]pyridin-2-yl)-N-phenylbenzamide derivatives have been prepared by one-pot three-component synthesis using...