Screening of Synthetic Isoxazolone Derivative Role in Alzheimer’s Disease: Computational and Pharmacological Approach

Neurochemical Research - Alzheimer's disease (AD) is age-dependent neurological disorder with progressive loss of cognition and memory. This multifactorial disease is characterized by...     

Binding analysis of ytterbium(III) complex containing 1,10-phenanthroline with DNA and its antimicrobial activity

To evaluate the biological preference of [Yb(phen)₂(OH₂)Cl₃](H₂O)₂ (phen is 1,10-phenanthroline) for DNA, interaction of Yb(III) complex with DNA in Tris–HCl buffer is studied by various biophysical and spectroscopic techniques which reveal that the complex binds to DNA. The results of fluorescence titration reveal that [Yb(phen)₂(OH₂)Cl₃](H₂O)₂ has strongly quenched in the presence of DNA. The binding site number n, apparent binding constant K _b, and the Stern–Volmer quenching constant K _SV are determined. ΔH ⁰, ΔS ⁰, and ΔG ⁰ are obtained based on the quenching constants and thermodynamic theory (ΔH ⁰?>?0, ΔS ⁰?>?0, and ΔG ⁰?<?0). The experimental results show that the Yb(III) complex binds to DNA by non-intercalative mode. Groove binding is the preferred mode of interaction for [Yb(phen)₂(OH₂)Cl₃](H₂O)₂ to DNA. The DNA cleavage results show that in the absence of any reducing agent, Yb(III) complex can cleave DNA. The antimicrobial screening tests are also recorded and give good results in the presence of Yb(III) complex.     

Evaluation of DNA,BSA binding,and antimicrobial activity of new synthesized neodymium complex containing 29-dimethyl 110-phenanthroline

In order to evaluate biological potential of a novel synthesized complex [Nd(dmp)₂Cl₃.OH₂] where dmp is 29-dimethyl 110-phenanthroline, the DNA-binding, cleavage, BSA binding, and antimicrobial activity properties of the complex are investigated by multispectroscopic techniques study in physiological buffer (pH 7.2).The intrinsic binding constant (K_b) for interaction of Nd(III) complex and FS–DNA is calculated by UV–Vis (K_b = 2.7 ± 0.07 × 10⁵) and fluorescence spectroscopy (K_b = 1.13 ± 0.03 × 10⁵). The Stern–Volmer constant (K_SV), thermodynamic parameters including free energy change (ΔG°), enthalpy change (?H°), and entropy change (?S°), are calculated by fluorescent data and Vant’ Hoff equation. The experimental results show that the complex can bind to FS–DNA and the major binding mode is groove binding. Meanwhile, the interaction of Nd(III) complex with protein, bovine serum albumin (BSA), has also been studied by using absorption and emission spectroscopic tools. The experimental results show that the complex exhibits good binding propensity to BSA. The positive ΔH° and ?S° values indicate that the hydrophobic interaction is main force in the binding of the Nd(III) complex to BSA, and the complex can quench the intrinsic fluorescence of BSA remarkably through a static quenching process. Also, DNA cleavage was investigated by agarose gel electrophoresis that according to the results cleavage of DNA increased with increasing of concentration of the complex. Antimicrobial screening test gives good results in the presence of Nd(III) complex system.     

Multispectroscopic DNA-binding studies of a terbium(III) complex containing 2,2′-bipyridine ligand

Agarose gel electrophoresis, absorption, fluorescence, viscosity, and circular dichroism (CD) have been used in exploring the interaction of terbium(III) complex, [Tb(bpy)₂Cl₃(OH₂)] where bipy is 2,2′-bipyridine, with Fish salmon DNA. Agarose gel electrophoresis assay, along with absorption and fluorescence studies, reveal interaction between the corresponding complex and FS-DNA. Also, the binding constants (K_b) and the Stern–Volmer quenching constants (K_sv) of Tb(III) complex with FS-DNA were determined. The calculated thermodynamic parameters suggested that the binding of mentioned complex to FS-DNA was driven mainly by hydrophobic interactions. A comparative study of this complex with respect to the effect of iodide-induced quenching, ionic strength effect, and ethidium bromide exclusion assay reflects binding of explicit to the FS-DNA primarily in a groove fashion. CD and viscosity data also support the groove binding mode. Furthermore, Tb(III) complex have been simultaneously screened for their antibacterial and antifungal activities.     

Praseodymium (III) complexes with 1,10-phenanthroline and cyanamide derivatives as N-donor ligands

The molecular structure of praseodymium (III) complex with 1,10-phenanthroline (phen), [Pr(phen)₂Cl₃·OH₂] (1) was determined by single-crystal X-ray diffraction. Crystal data: crystal system, triclinic, space group P and Z = 2, a = 7.1110(7) ?, b = 10.1716(10) ?, c = 17.2367(18) ?, α = 80.922(5)°, β = 78.759(5)°, γ = 70.151(5)°, R₁ = 0.036; wR₂ = 0.076 for all data. Treatment of aqueous solution of [Pr(phen)₂Cl₃·OH₂] (1) with thallium phenylcyanamide salts yield [Pr(phen)₂(L)₃] (L = pcyd (2), 2-Clpcyd (3), 2,3,5-Cl₃pcyd (4), 2,3,4,5-Cl₄pcyd (5)). Four new praseodymium (III) complexes have been characterized by IR, UV-Vis and ¹H NMR spectroscopy as well as elemental analysis. The ¹H NMR spectra of these complexes show broadening of ligand protons attributed to coordination of paramagnetic center.     

Simultaneous and sensitive determination of a quaternary mixture of AA, DA, UA and Trp using a modified GCE by iron ion-doped natrolite zeolite-multiwall carbon nanotube

The evaluation of a novel modified glassy carbon electrode modified with iron ion-doped natrolite zeolite-multiwalled carbon nanotube for the simultaneous and sensitive determination of ascorbic acid (AA), dopamine (DA), uric acid (UA) and tryptophan (Trp) has been described. The measurements were carried out using cyclic voltammetry in buffer solution with pH 1. This modified electrode exhibits potent and persistent electroxidation behavior followed by well-separated oxidation peaks towards AA, DA, UA and Trp with increasing of the oxidation current. For the quaternary mixture containing AA, DA, UA and Trp, the 4 compounds can well separate from each other at the scan rate of 100 mVs(-1) with a potential difference of 270 mV, 150 mV and 260 mV for the oxidation peak potentials of AA-DA, DA-UA and UA-Trp, respectively, which was large enough to simultaneous determine AA, DA, UA and Trp. The catalytic peak current obtained, was linearly dependent on the AA, DA, UA and Trp concentrations in the range of 7.77-833 μM, 7.35-833 μM, 0.23-83.3 μM and 0.074-34.5 μM and the detection limits for AA, DA, UA and Trp were 1.11, 1.05, 0.033 and 0.011 μM, respectively. The analytical performance of this sensor has been evaluated for simultaneous detection of AA, DA, UA and Trp in human serum and urine samples.     

Electronic and fluorescent studies on the interaction of DNA and BSA with a new ternary praseodymium complex containing 2,9-dimethyl 1,10-phenanthroline and antibacterial activities testing

In this study, fluorescence emission spectra, UV–vis absorption spectra, ethidium bromide (EB)-competition experiment, and iodide quenching experiment were used for the interaction study of the Fish salmon DNA (FS-DNA) with [Pr(dmp)2Cl3(OH2)] where dmp is 2,9-dimethyl 1,10-phenanthroline. The binding constant and the number of binding sites of the complex with FS-DNA were 6.09?±?0.04 M^?1 and 1.18, respectively. The free energy, enthalpy, and entropy changes (ΔG°, ΔH°, and ΔS°) in the binding process of the Pr(III) complex with FS-DNA were –8.02?kcal mol^?1, +39.44?kcal mol^?1, and +159.56?cal mol^?1 K^?1, respectively. Based on these results, the interaction process between FS-DNA with [Pr(dmp)2Cl3(OH2)] was spontaneous and the main binding interaction force was groove binding mode. Also, Fluorescence and electronic absorption spectroscopy were used in order to evaluate the binding characteristics, stoichiometry, and interaction mode of praseodymium(III) (Pr(III)) complex with bovine serum albumin (BSA). Title complex showed good binding propensity to BSA presenting moderately high Kb values. The fluorescence quenching of BSA by Pr(III) complex has been observed to be the static process. The positive ΔH° and ΔS° values showed that the hydrophobic interaction is the main force in the binding of Pr(III) complex and BSA. Eventually, the average aggregation number, <J>, of BSA potentially induced by title complex confirmed the 1:1 stoichiometry for title complex-BSA adducts. In vitro, antimicrobial activity of title complex was indicated that the complex is more active against both Escherichia coli and Enterococcus faecalis bacterial strains than Staphylococcus aureus, and Pseudomonas aeruginosa.

Communicated by Ramaswamy H. Sarma     

DNA interaction of europium(III) complex containing 2,2′-bipyridine and its antimicrobial activity

The interaction of native fish salmon DNA (FS-DNA) with [Eu(bpy)₃Cl₂(H₂O)]Cl, where bpy is 2,2′-bipyridine, is studied at physiological pH in Tris-HCl buffer by spectroscopic methods, viscometric techniques as well as circular dichroism (CD). These experiments reveal that Eu(III) complex has interaction with FS-DNA. Moreover, binding constant and binding site size have been determined. The value of K_b has been defined 2.46 ± .02 × 10⁵ M^?1. The thermodynamic parameters are calculated by Van’t Hoff equation, the results show that the interaction of the complex with FS-DNA is an entropically driven phenomenon. CD spectroscopy followed by viscosity as well as fluorescence and UV––Vis measurements indicate that the complex interacts with FS-DNA via groove binding mode. Also, the synthesized Eu(III) complex has been screened for antimicrobial activities.     

Synthesis, molecular structure, and properties of six-coordinate iron(III) porphyrin, [OEPFe(Pz)2]ClO4

The effect of pyrazine as axial ligand on the formation and coordination of heme analogue has been studied. A new six coordinate and stable iron(III) heme analogue, [OEPFe^III(Pz)₂]ClO₄, where OEP is octaethylporphyrin and Pz is pyrazine, has been isolated. The compound has been characterized by different spectroscopic methods ¹H NMR, UV-Vis, IR as well as elemental analysis. ¹H NMR spectroscopy and magnetic moment measurements show that [OEPFe^III(Pz)₂]ClO₄ is paramagnetic and iron is six coordinate. The structure of [OEPFe^III(Pz)₂]ClO₄ has been determined by X-ray diffraction analysis. The four Fe-N_p, bond distances have average values of 1.985 Å.