The decomposition kinetics of hydrogen peroxide catalyzed by diethylenetriaminepentaacetatoiron(III) complex

The rate of reaction of (Fe(DTPA)) with H₂O₂ was investigated at various temperatures. The observed rate law is given by the expression. The rate constants and the related thermodynamic parameters are calculated. Substitution controlled mechanisms are suggested to account for the formation of the violet peroxy intermediate. The results are compared with previously data for Fe EDTA complex.     

Anti-inflammatory,antioxidant and antiangiogenic activities of diosgenin isolated from traditional medicinal plant,Costus speciosus (Koen ex.Retz.) Sm

Costus speciosus is an important medicinal plant widely used in several indigenous medicinal formulations. The present study was conducted to evaluate the in vitro anti-inflammatory, antioxidant and antiangiogenic activities of diosgenin isolated from C. speciosus. The diosgenin was isolated from C. speciosus by HPTLC and its biological activities were studied by different protocols. The results demonstrated that LPS stimulated TNF-α generation in RAW 264.7 macrophage culture supernatant up to 3.7-fold of the control and that sample treatment (50 μg/mL) resulted in a highly significant inhibitory effect on LPS-stimulated TNF-α (p < 0.01) in a similar manner to methotrexate inhibitory effect. The tested sample possessed an effective antioxidant scavenging affinity against DPPH radicals as compared with the standard antioxidant activity of vitamin C. The results presented here may suggest that diosgenin isolated from C. speciosus possess anticancer, apoptotic and inhibitory effects on cell proliferation.     

Design and application of molecularly imprinted electrochemical sensor for the new generation antidiabetic drug saxagliptin

Saxagliptin (Saxa) belongs to a new generation of antidiabetic pharmaceutical compounds used in combination with healthy diet and exercise to lower blood glucose levels in patients with type 2 diabetes mellitus (T2DM). In this work, we report for the first time a molecularly imprinted polymer (MIP) based electrochemical sensor for the determination of Saxa. Computational calculations were performed, based on which five MIPs were synthesized using Saxa as a template, itaconic acid as a monomer, crosslinked with ethylene glycol dimethacrylate and Di methyl sulfoxide (DMSO) as a porogen with different ratios. Non-covalent interaction (NCI) analysis has been also conducted, and the obtained isosurface analysis was used for graphical visualization of NCI that could occur in real space as well as for the discrimination between hydrogen bond interaction, Van Der Waals attraction and spatial repulsion. The optimized polymer was incorporated as a modifier for designing an electrochemical sensor comprising MIP and Multiwalled carbon nanotubes (MwCNT) within carbon paste electrode (CPE). The operational variables including incubation time, pH, scan rate, and accumulation time were optimized. The sensor showed linearity over the concentration range (1 × 10⁻⁹–1 × 10⁻¹⁵ M) with low limit of detection (LOD) 8 × 10⁻¹⁶ and 2 × 10⁻¹⁶ M on using DPV and EIS, respectively. The sensor was successfully applied for pharmaceutical formulations, urine, and human serum samples with recovery range between 97.45–100.64 %.     

Structure, self-assembly, and dual role of a beta-defensin-like peptide from the Chinese soft-shelled turtle eggshell matrix

Biomineral matrix formation and molecular recognition are two important processes associated with eggshell biomineralization. To understand these two processes, a major intracrystalline peptide, pelovaterin, was isolated from turtle (Pelodiscus sinensis) eggshell and its tertiary and quaternary structures were established. The global fold of pelovaterin is similar to that of human beta-defensins but has a large hydrophobic core and a short hydrophilic N-terminal segment, which is not preserved in defensins. Pelovaterin exhibits strong antimicrobial activity against two pathogenic gram-negative bacteria, Pseudomonas aeruginosa and Proteus vulgaris, and stabilizes a thin film of metastable vaterite. We show that pelovaterin self-aggregates in the form of micellar nanospheres and the aggregation in solution is entropy-driven. It is suggested that the micellar aggregation of pelovaterin is responsible for the induction and stabilization of the metastable phase by altering the interfacial energy. The results demonstrate the adaptability of an extracellular matrix protein to perform multiple tasks: polymorph discrimination and protection of the contents of the egg against bacterial invasion.     

Spectroscopic Behavior and Photophysical Parameters of 2-(Acetoxymethyl)-6-(1,2,4-triazinylaminodihydroquinazolinyl)tetrahydropyran Derivative in Different Solid Hosts

Journal of Fluorescence - Optical and photophysical properties of 6-substituted-1,2,4-Triazine fluorescent derivative dye doped in silicate based sol–gel, homopolymer of methyl methacrylate...     

Kinetics of interaction and complexation of the palladium(II) ion with new para-substituted-phenylazo-R-acid chromophores

The kinetics of complex formation between the Pd^II ion and the new phenylazo-R-acid chromophore [HL] and it is para-substituted derivatives {X = H, Cl, CO₂H, and SO₂NH₂}, [p-X-HL], have been studied at various temperatures. The observed rate constant is given by:k_obs=/k₁ K₁/K[H⁺]+k₂ K₂}[p-X-HL]A mechanism involving initial formation of a 1:1 complex between the Pd^II ion and [p-X-HL], followed by aquation as the rate-determining step, is proposed. The activation enthalpy and entropy for the aquation were determined. The rate of formation is greatly effected by electron-withdrawing substitutents in the para position of the phenylazo-R-acid ligand. The solid complex of p-SO₂NH₂-phenylazo-R-acid has been prepared and characterized by elemental analysis, and FT-IR spectra. The p-substituted-phenylazo-R-acid ligands are very active against C. albicans fungi, so that these compounds can be used for the chemotherapy of candidiasis and other fungal skin diseases.     

Synthesis of several new lanthanide Glimepiride complexes for evaluation of microbial activity

The complexation between lanthanide metal ions like Nd(III), Tb(III), and Er(III) with Glimepiride produces 1: 1 molar ratio (metal: Glimepiride) monodentate complexes of general formula: [M(GMP)(H₂O)₄]Cl₃·xH₂O, where: M = Nd, Tb, and Er, x = 1, 10, respectively. The structures of obtained compounds were assigned by IR, ¹H NMR and UV/Vis spectra. Themogravimetric analysis and kinetic thermodynamic parameters have proved the thermal stability of Glimepiride complexes. Obtained lanthanide complexes showed significant effect against some bacteria and fungi.     

Unique plastic and recovery behavior of nanofilled elastomers and thermoplastic elastomers (Payne and Mullins effects)

We have proposed recently that the mechanical properties of nano-filled elastomers are governed by the kinetics of rupture and re-birth of glassy bridges which link neighboring nanoparticles and allow for building large rigid clusters of finite life-times. The latter depend on parameters such as the temperature, the nanoparticle-matrix interaction, and the distance between neighboring fillers. Most importantly these life-times depend on the history of deformation of the samples. We show that this death and re-birth process allows for predicting unusual non-linear and plastic behavior for these systems. We study in particular the behavior after large deformation amplitude cycles. At some point we put the systems at rest under large deformation, and let the stress relax in this new deformed state. During this relaxation process the life-time of glassy bridges increases progressively, even for large deformation states. The systems thus acquire a new reference state, which corresponds to a plastic deformation. The stretching energy of the polymer strands of the rubbery matrix is larger than in the initial undeformed state, but this effect is compensated by a new configuration of glassy bridges, which are much stiffer. For plastic deformations of less than about 10%, the new system acquires mechanical properties around this new reference state which are very close to those of the initial system. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1495–1508, 2010     

Smooth Density for Some Nilpotent Rough Differential Equations

In this note, we provide a nontrivial example of a differential equation driven by a fractional Brownian motion with Hurst parameter 1/3<H<1/2 whose solution admits a smooth density with respect to Lebesgue measure. The result is obtained through the use of an explicit representation of the solution when the vector fields of the equation are nilpotent, plus a Norris-type lemma in the rough paths context.     

A Highly Stereoselective Synthesis of Glycidic Amides Based on a New Class of Chiral Sulfonium Salts: Applications in Asymmetric Synthesis

A new type of chiral sulfonium salts that are characterized by a bicyclic system has been designed and synthesized from α‐amino acids. Their corresponding ylides, which were prepared by basic treatment of the sulfonium salts, reacted smoothly with a broad array of simple and chiral aldehydes to provide trans‐epoxy amides in reasonable to very good yields and excellent stereoselectivities (>98 %). The obtained epoxy amides were found to be useful as synthetic building blocks. Thus, they were reduced into their corresponding epoxy alcohols and subjected to oxirane‐ring‐opening reactions with different types of nucleophiles.