Antioxidant capacity and phenolic composition of leaves from 10 Bene (Pistacia atlantica subsp. kurdica) genotypes

Leaves of 10 Bene genotypes were collected from six provinces (West Azerbaijan, Kurdistan, Kermanshah, Ilam, Hamedan and Lorestan) in Iran. This study was carried out to better characterise the total phenolic and flavonoid contents, antioxidant capacity and phenolic composition, as well as to evaluate the correlation between content of phenolic compounds and antioxidant activity in 10 genotypes of Bene. The antioxidant activity of leaf extracts was measured using different assays: ferric reducing antioxidant power, nitric oxide radical scavenging and 2,2-diphenyl-1-picrylhydrazyl. The results indicated that the antioxidant capacity can be related to total phenolic and flavonoid content, so that among all the genotypes studied here, the highest and the lowest phenolic content and antioxidant activity were observed in B2 and B10 genotypes, respectively. Analysing the phenolic composition using high performance liquid chromatography, caffeic acid, vanillic acid, ferulic acid and sinapic acid were found in all investigated genotypes.     

Simultaneous determination of potassium clavulanate and cefixime in synthetic mixtures by high-performance liquid chromatography

A simple, precise, and sensitive high-performance liquid chromatographic method was developed and validated for the simultaneous determination of potassium clavulanate and cefixime in synthetic mixture form. The analytes were separated on a C18 column by using 0.03 M disodium hydrogen phosphate buffer (pH 6.5)-methanol (84 + 16, v/v) as the mobile phase with detection at 220 nm. The method exhibited high sensitivity and good linearity in the concentration ranges of 12.5-62.5 and 20-100 microg/mL for potassium clavulanate and cefixime, respectively. The total run time for the 2 components was <8 min, and the average recovery was >101.5% with a relative standard deviation of <1.0%. The proposed method was validated according to guidelines of the International Conference on Harmonization by evaluation of linearity, recovery, selectivity, robustness, limits of detection and quantitation, and within- and between-day precision. The results obtained for the synthetic mixture show that the method is highly precise and accurate for the simultaneous determination of potassium clavulanate and cefixime.     

Frame properties of wave packet systems in L^2({\mathbb R}^d)

Extending work by Hernandez, Labate and Weiss, we present a sufficent condition for a generalized shift-invariant system to be a Bessel sequence or even a frame for . In particular, this leads to a sufficient condition for a wave packet system to form a frame. On the other hand, we show that certain natural conditions on the parameters of such a system exclude the frame property.      

An electrochemical DNA sensor for determination of 6-thioguanine using adsorptive stripping voltammetry at HMDE: An anticancer drug DNA interaction study

In the present study, the electrochemical behavior of 6-Thioguanine (6-TG) and its interaction with double-strand DNA (ds-DNA) were investigated at the surface of hanging mercury drop electrode (HMDE) in neutral media. The interaction of 6-TG with ds-DNA in neutral buffer was clearly demonstrated by the elimination of 6-TG signal and the advent of a new reduction peak. To investigate the interaction, various parameters including accumulation time and potential as well as ds-DNA concentration were optimized using a combination of adsorptive stripping voltammetry (AdSV) and square wave voltammetry (SWV) techniques. As a consequence a low detection limit of 1.1 μM was obtained in a dynamic range of 16.0 to 360.0 μM. To better understand the interaction mechanism between 6-TG anti-cancer drug and ds-DNA, cyclic voltammetry and UV-Vis spectroscopy measurements were carried out and the intercalation of 6-TG into ds-DNA was proposed as the plausible mechanism. The application of this screening assay in real sample analysis was investigated by using the procedure for determination of 6-TG in 6-Thioguanine tablets and also in spiked 6-TG blood serum. Overall, the results were indicative of a DNA sensor which could be applied effectively in the analysis of 6-TG in vitro.     

Study on the interaction of three structurally related cationic Pt(II) complexes with human serum albumin: importance of binding affinity and denaturing properties

Human serum albumin (HSA) primarily functions as a transport carrier for a vast variety of natural ligands and pharmaceutical drugs. In the present study, three structurally related cationic Pt(II) complexes ([Pt(ppy)(dppe)]CF₃CO₂: 1, Pt(bhq)(dppe)]CF₃CO₂: 2, and [Pt(bhq)(dppf)]CF₃CO₂: 3) were used to evaluate their interaction with HSA under different experimental setups, using UV–Vis absorption spectroscopy, fluorescence and circular dichroism techniques. The spectroscopic results suggest that upon binding to HSA, the Pt(II) complexes could effectively induce structural alteration of the protein. The complexes can bind to HSA with the binding affinities of the following order: 3 > 2 > 1. Also, thermodynamic parameters of binding between these complexes and HSA indicated the existence of entropy-driven spontaneous interaction which primarily dominated with the hydrophobic forces. Also, docking simulation study revealed the binding details of these complexes on HSA. Complex 3 with highest binding affinity for HSA indicates lowest denaturing effect on this protein. The low denaturation properties of 3 appear important in the terms of lower susceptibility of this platinum complex for possible development of deleterious side effects.     

Synthesis and characterization of new soluble thermally stable poly(azomethine‐ether‐imide)s: discerning the possibility for high temperature applications

A new series of polyimides was synthesized by the condensation of monomers (azomethine‐ether diamine, DA‐1 and DA‐2) with pyromelliticdianhydride (PMDA), 3,4,9,10‐perylenetetracarboxylic dianhydride (PD) and 3,3′4,4′‐benzophenonetetracarboxylic dianhydride (BD). The structural explications of monomers and polyimides was conducted by FT‐IR, ¹H NMR and elemental analysis. All polyimides were found soluble in polar aprotic solvents and found to be semicrystalline in nature confirmed by XRD. The inherent viscosities were found in the range of 0.67–0.77 g/dl. %. Average molecular weight (M_W) and number average molecular weight (Mn) of the polyimides were found in the range of 5.72 × 10⁵ g/mol–6.58 × 10⁵ g/mol and 3.79 × 10⁵ g/mol 4.11 × 10⁵ g/mol respectively. The polyimides exhibited excellent thermal properties having a glass transition temperature T_g in the range of 230–290°C and the 10% weight loss temperature was above 450°C. The values of thermodynamic parameters, activation energy, enthalpy and entropy fall in the range of 45.2–53.90 kJ/mol, 43.5–52.30 kJ/mol and 0.217 kJ/mol k to 0.261 kJ/mol k respectively. Copyright © 2015 John Wiley & Sons, Ltd.     

Structure-retention and mobile phase-retention relationships for reversed-phase high-performance liquid chromatography of several hydroxythioxanthone derivatives in binary acetonitrile-water mixtures

The reversed-phase high-performance liquid chromatographic (RP-HPLC) behavior of some newly synthesized hydroxythioxanthone derivatives using binary acetonitrile-water mixtures as mobile phase has been examined. First, the variation in the retention time of each molecule as a function of mobile phase properties was studied by Kamlet-Taft solvatochromic equations. Then, the influences of molecular structure of the hydroxythioxanthone derivatives on their retention time in various mobile phase mixtures were investigated by quantitative structure-property relationship (QSPR) analysis. Finally, a unified model containing both the molecular structure parameters and mobile phase properties was developed to describe the chromatographic behavior of the systems studied. Among the solvent properties, polarity/polarizability parameter (π^*) and hydrogen-bond basicity (β), and among the solute properties, the most positive local charge (MPC), the sum of positive charges on hydrogen atoms contributing in hydrogen bonding (SPCH) and lipophilicity index (log P) were identified as controlling factors in the RP-HPLC behavior of hydroxythioxanthone derivatives in actonitrile-water binary solvents.     

Coupling Microplate-Based Antibacterial Assay with Liquid Chromatography for High-Resolution Growth Inhibition Profiling of Crude Extracts: Validation and Proof-of-Concept Study with Staphylococcus aureus

With the identification of novel antibiotics from nature being pivotal in the fight against human pathogenic bacteria, there is an urgent need for effective methodologies for expedited screening of crude extracts. Here we report the development and validation of a simple and dye-free antimicrobial assay in 96-well microplate format, for both determination of IC₅₀ values and high-resolution inhibition profiling to allow pin-pointing of bioactive constituents directly from crude extracts. While commonly used antimicrobial assays visualize cell viability using dyes, the developed and validated assay conveniently uses OD₆₀₀ measurements directly on the fermentation broth. The assay was validated with an investigation of the inhibitory activity of DMSO against Staphylococcus aureus, temperature robustness, interference by coloured crude extracts as well as inter-day reproducibility. The potential for high-resolution S. aureus growth inhibition profiling was evaluated on a crude extract of an inactive Alternaria sp., spiked with ciprofloxacin.     

Acidified Nitrite Accelerates Wound Healing in Type 2 Diabetic Male Rats: A Histological and Stereological Evaluation

Impaired skin nitric oxide production contributes to delayed wound healing in type 2 diabetes (T2D). This study aims to determine improved wound healing mechanisms by acidified nitrite (AN) in rats with T2D. Wistar rats were assigned to four subgroups: Untreated control, AN-treated control, untreated diabetes, and AN-treated diabetes. AN was applied daily from day 3 to day 28 after wounding. On days 3, 7, 14, 21, and 28, the wound levels of vascular endothelial growth factor (VEGF) were measured, and histological and stereological evaluations were performed. AN in diabetic rats increased the numerical density of basal cells (1070 ± 15.2 vs. 936.6 ± 37.5/mm³) and epidermal thickness (58.5 ± 3.5 vs. 44.3 ± 3.4 μm) (all p < 0.05); The dermis total volume and numerical density of fibroblasts at days 14, 21, and 28 were also higher (all p < 0.05). The VEGF levels were increased in the treated diabetic wounds at days 7 and 14, as was the total volume of fibrous tissue and hydroxyproline content at days 14 and 21 (all p < 0.05). AN improved diabetic wound healing by accelerating the dermis reconstruction, neovascularization, and collagen deposition.     

Indole‐3‐acetic acid and N‐acetyltryptophan corrosion inhibition effects on mild steel in 1 M hydrochloric acid solution

Corrosion inhibition of indole‐3‐acetic acid and N‐acetyl tryptophan on carbon steel was investigated using polarization and electrochemical impedance spectroscopy (EIS). Polarization results revealed that corrosion inhibitors could reduce the rate of cathodic and anodic reactions on metal surface. EIS analysis showed inhibition efficiency of indoles increases by increasing the inhibitor concentration. The maximum inhibition efficiency was 97% and 80% in solutions containing 10 mM indole‐3‐acetic acid and 10 mM N‐acetyl tryptophan, respectively. The adsorption of inhibitors was found to follow Langmuir isotherm. Adsorption and film formation of inhibitors on the metal substrate were confirmed by calculating thermodynamic adsorption parameter (ΔG⁰_ads) and characterization of exposed metals' surface through contact angle measurements. Copyright © 2014 John Wiley & Sons, Ltd.