Synthesis,spectral properties,in vitro α-glucosidase inhibitory activity and quantum chemical calculations of novel mixed-ligand M(II) complexes containing 1,10-phenanthroline

A series of mixed-ligand M(II) complexes containing 1,10-phenanthroline (phen) and 3-methylpyridine-2-carboxylic acid (3-mpaH) or 6-methylpyridine-2-carboxylic acid (6-mpaH), namely [Co(3-mpa)₂(phen)]·3H₂O ( 1 ), [Hg(6-mpa)₂(phen)]·2H₂O ( 2 ), [Mn(6-mpa)₂(phen)]·2H₂O ( 3 ), [Co(6-mpa)₂(phen)]·H₂O ( 4 ) and [Ni(6-mpa)₂(phen)]·H₂O ( 5 ), were synthesized for the first time. Among them, 1 was obtained as single crystals. The structural characterization for 1 was conducted using X-ray diffraction and that for 2 – 5 using mass spectrometry. The IC₅₀ values for α-glucosidase inhibition of 1 – 5 were obtained as 0.161 to >600 μM. The spectral properties were also investigated using Fourier transform infrared and UV–visible spectra. Furthermore, to investigate the geometrical parameters, spectral and electronic properties and second- and third-order nonlinear optical parameters for 1 – 5 , density functional calculations were applied.     

A novel series of M(II) complexes of 6‐methylpyridine‐2‐carboxylic acid with 4(5)methylimidazole: Synthesis,crystal structures, α‐glucosidase activity,density functional theory calculations and molecular docking

Novel complexes of 6‐methylpyridine‐2‐carboxylic acid and 4(5)methylimidazole, namely [Mn(6‐mpa)₂(4(5)MeI)₂] ( 1 ), [Zn(6‐mpa)₂(4(5)MeI)₂] ( 2 ), [Cd(6‐mpa)₂(4(5)MeI)₂] ( 3 ), [Co(6‐mpa)₂(4(5)MeI)₂] ( 4 ), [Ni(6‐mpa)₂(4(5)MeI)(OAc)] ( 5 ) and [Cu(6‐mpa)₂(4(5)MeI)] ( 6 ), were synthesized for the first time. The structures of complexes 1 – 4 and complexes 5 and 6 were determined using X‐ray diffraction and mass spectrometric techniques, respectively. The experimental spectral analyses for these complexes were performed using Fourier transform infrared and UV–visible techniques. The α‐glucosidase inhibition activity values (IC₅₀) of complexes 1 – 6 were identified in view of genistein reference compound. Moreover, the DFT/HSEh1PBE/6‐311G(d,p)/LanL2DZ level was used to obtain optimal molecular geometry and vibrational wavenumbers for complexes 1 – 6 . Electronic spectral behaviours and major contributions to the electronic transitions were investigated using TD‐DFT/HSEh1PBE/6‐311G(d,p)/LanL2DZ level with conductor‐like polarizable continuum model and SWizard program. Finally, in order to investigate interactions between the synthesized complexes ( 1 – 6 ) and target protein (template structure S. cerevisiae isomaltase), a molecular docking study was carried out.     

Synthesis,antioxidant activity and SAR study of novel spiro-isatin-based Schiff bases

Molecular Diversity - A new series of 21 Schiff bases of spiro-isatin was synthesized, and their DPPH, CUPRAC and ABTS cation radical scavenging abilities were investigated for antioxidant...     

Nucleon’s Axial-Vector Form Factor in the Hard-Wall AdS/QCD Model

The axial-vector form factor of the nucleons is considered in the framework of hard-wall model of holographic QCD. A new interaction term between the bulk gauge and matter fields was included into the interaction Lagrangian. We obtain the axial-vector form factor of nucleons in the boundary QCD from the bulk action using AdS/CFT correspondence. The momentum square dependence of the axial-vector form factor is analysed numerically.     

Synthesis and characterization of thermoresponsive poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide-co-<Emphasis Type="Italic">N</Emphasis>-hydroxymethylacrylamide-co-2-hydroxyethyl methacrylate) hydrogels

Thermoresponsive hydrogels based on N-isopropylacrylamide, N-hydroxymethylacrylamide, and 2-hydroxyethyl methacrylate, poly(NIPAM–co-NHMAAm–co-HEMA), have been synthesized and their swelling—deswelling behavior studied as a function of NIPAM concentration, NIPAM/NHMAAm and NIPAM/HEMA mole ratio, and total monomer concentration. Copolymers varying in composition have been obtained by redox copolymerization of these three monomers. Temperature has been changed in the ranges from 4 to 70 °C at fixed pH and total ionic strength. Equilibrium swelling ratio, dynamic swelling ratio, and dynamic deswelling ratio were evaluated for all hydrogel systems. The equilibrium swelling ratios of the copolymeric gels decrease with increasing NHMAAm and HEMA content. The formation of the intermolecular hydrogen bonding between hydroxyl and amido groups decreases the hydrophilic group numbers of the gel and the affinity of the gel towards water decreases. The copolymer gels also showed rapid volume transitions with time. The time required for equilibrium shrinking increased with increasing NHMAAm and HEMA content in the gel.     

Determination of Kinetic Parameters of Ethyl Methacrylate Polymerization Initiated by the Redox Pair SO2-tert-Butyl Hydroperoxide

Abstract

In the bulk polymerization of ethyl methacrylate with the redox initiator pair sulfur dioxide-tert-butyl hydroperoxide (SO₂-TBHP), the kinetic parameters were determined by the dead-end polymerization technique using the dilatometric method. Polymerization was conducted with various initiator pair compositions in the temperature interval of 12–35°C. An activation energy of 14.1 kJ/mol for [SO₂]/[TBHP] = 0.44 was determined for this temperature range. The values of k ² _p/k _t obtained in this study were in the interval 1.34 × 10^?4 to 1.11 × 10^?3 L/mol·s. The f/k _d ratios for the redox pair at different temperatures and for different initiator ratios were also calculated. The f/k _d ratios of the initiator pair changed between 15.1 and 187.6 seconds. The wide variations in these kinetic parameters were explained on the basis of competitive reactions between the redox pair and their reaction products.     

Preparation and characterization of 3-[(1H-1,2,4-triazole-3-ylimino)methyl]naphtalene-2-ol film at the platinum surface for selective voltammetric determination of dopamine in the presence of uric acid and ascorbic acid

A [(1H-1,2,4-triazole-3-ylimino)methyl]naphthalene-2-ol (TMN-2-ol) film modified platinum (Pt) electrode has been fabricated by the electrochemical oxidation in acetonitrile solution. The modified surface was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). The prepared Pt electrode can be used as a functional interface to sensitive and selective determination of dopamine (DA) in the presence of uric acid (UA) and ascorbic acid (AA) by square wave voltammetry (SWV) method. The limit of detection (LOD) and limit of quantification (LOQ) of DA were 9.25 × 10⁻⁸ and 2.78 × 10⁻⁷ M, respectively. Linear range of DA was found to be between 3.95 × 10⁻⁷ and 4.19 × 10⁻⁶ M.     

A Possible Relationship Between Serum Satellite DNA and Cellular Antioxidative Mechanism

The presence of circulating free DNA in the sera of cancer patients has been reported by different authors. Moreover, a hypothetical relationship between the DNA level and different stages of the disease has also been suggested. In this work, the free serum DNA level in various cancer patients was measured and consistent results with the reported data were found. (1,4) To assess the possible mechanism for the release of this fraction and to explain the high levels observed in cancer patients levels of the bivalent intracellularcation, magnesium were determined. Further to relate the process to the antioxidative mechanism of the cell membrane also selenium levels were measured simultaneously. The serum free DNA and the magnesium concentration of the patients before treatment were significally higher and the selenium levels lower than the control group. After appropriate the rapy the magnesium levels were found to decline while the high free DNA and low selenium values still persisted. These findings imply that the membrane stability and permeability is impaired due both to the neoplastic changes and later to the effect of chemotherapeutic agents with the result that intracellular material is released into the circulation.     

Diffusion-controlled evaporation of sodium dodecyl sulfate solution drops placed on a hydrophobic substrate

In this work, the effect of SDS anionic surfactant on the diffusion-controlled evaporation rate of aqueous solution drops placed on TEFLON-FEP substrate was investigated with 11 different SDS concentrations. Drop evaporation was monitored in a closed chamber having a constant RH of 54-57% by a video camera. The initial contact angle, θ(i) decreased from 104±2° down to 68±1° due to the adsorption of SDS both at the water-air and the solid-water interfaces. The adsorption of SDS on the solid surface was found to be 76% of that of its adsorption at the water-air interface by applying Lucassen-Reynders approach. An equation was developed for the comparison of the evaporation rates of drops having different θ(i) on the same substrate. It was found that the addition of SDS did not alter the drop evaporation rate considerably for the first 1200 s for all the SDS concentrations. The main difference was found to be the change of the mode of drop evaporation by varying the SDS concentration. The constant θ mode was operative up to 80 mM SDS concentration, whereas constant contact area mode was operative after 200 mM SDS concentrations due to rapid drop pining on the substrate.     

Model systems for flavoenzyme activity: site-isolated redox behavior in flavin-functionalized random polystyrene copolymers

[reaction: see text] A model system has been developed to study the redox behaviors of flavin derivatives appended onto random polystyrene copolymers through "click" chemistry strategies. The results demonstrate that flavin units attached onto polymers exhibit site-isolated redox behaviors, yielding new materials with electrochemically tunable associations (K(a)(ox) = 450 M(-)(1), K(a)(red) = 18,200 M(-)(1)) to complementary diamidopyridine (DAP) functionality.