Clofarabine Targets the Large Subunit (α) of Human Ribonucleotide Reductase in Live Cells by Assembly into Persistent Hexamers

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Highlights? Expression/isolation of active human RNR-α from mammalian cells is developed ? Strategy unveils Clofarabine mechanism and in-cell-relevance of α-oligomerization ? Independent biochemical and structural methods document in-cell-assembled α-hexamers ? Drug-induced hexameric states have remarkable kinetic stability     

Multimodal K-shortest viable path problem in Tehran public transportation network and its solution applying ant colony and simulated annealing algorithms

This paper treats with K-shortest viable path problem in a transportation network including multiple modes. The considered modes are metro, rapid-bus, private and walking. In this network, a viable path is one that the number of mode changes is limited and the traverse time and also the walking, metro and private usage are restricted subjected to some constraints. The traverse time is defined dependent on congestion level. Because constrained shortest path is NP-hard, we extend two metaheuristic algorithms namely GASA and BACS for the given problem. GASA is a Greedy Algorithm Simulated Annealing and BACS is a bi-direction searching Ant Colony System made by two colonies of ants. We evaluate the validation of these algorithms applying several multimodal random networks. In addition, their results are compared with CPLEX 12.1. We find that GASA is appropriate for small networks and BACS has better performance in median and large-scale networks. Our results on Tehran network also demonstrate that BACS provides better objective values than BACS ones because Tehran public transportation is sparse.     

Colloidal Nanogold-Based Immunochromatographic Strip Test for the Detection of Digoxin Toxicity

Digoxin is widely used as a cardiac glycoside drug in the treatment of various heart conditions. Because it is a toxic drug, it should be regularly monitored in the serum of patients under treatment. In this study, colloidal nanogold is synthesized and the preparation of nanogold-labeled monoclonal antibody probe to digoxin is described under optimal conditions. In addition, an immunochromatographic (IC) method for digoxin analysis employing nanogold-labeled probe is developed. With this technique, it requires only 5 min to complete the quantitative detection of digoxin. The detection time is decreased 20–30 times in comparison to radioimmunoassay (RIA). The sensitivity to digoxin was about 2 ng/ml by naked eye, which is within the therapeutic and toxic ranges of digoxin. The results of serum samples obtained by IC strip were in agreement with those obtained by RIA. The IC strip was sufficiently sensitive and accurate to be used for the rapid detection of digoxin in serum samples.     

Adsorption characteristics of malachite green dye onto novel kappa-carrageenan-g-polyacrylic acid/TiO2–NH2 hydrogel nanocomposite

Batch adsorption experiments were carried out for the removal of malachite green (MG) cationic dye from aqueous solution using novel hydrogel nanocomposite that was prepared by graft copolymerization of acrylic acid (AA) onto kappa-carrageenan (κC) biopolymer in the presence of a crosslinking agent, a free radical initiator and aminosilica-functionalized TiO₂ nanoparticles (κC-g-PAA/TiO₂–NH₂). The factors influencing adsorption capacity of the adsorbents such as initial pH value (pH₀) of the dye solutions, TiO₂–NH₂ content (wt%), initial concentration of the dye, amount of adsorbents, and temperature were investigated. The adsorption capacity of hydrogel nanocomposite for MG was compared with hydrogel. The adsorption behaviors of both adsorbents showed that the adsorption kinetics and isotherms were in good agreement with a pseudo-second-order equation and the Langmuir equation. The high adsorption capacity (q _m= 666–833 (mg/g)) and the favorable heterogeneity factor (n = 1.2–1.5) calculated from isotherm equations show the efficiency of the novel adsorbents.     

Influence of saffron carotenoids and mulberry anthocyanins as natural sensitizers on performance of dye-sensitized solar cells

Ionics - This study reports the effect of saffron carotenoids and mulberry anthocyanins as natural sensitizers on electron transfer process and performance of dye-sensitized solar cells (DSSCs). A...     

Preparation and evaluation of a polymeric gel containing ionic liquid‐functionalized MWCNTs as a novel class of organic solvent absorbent

Multiwalled carbon nanotubes grafted with vinyl immidazolium‐based ionic liquid (MWCNT‐IL) were synthesized and utilized as a crosslinking agent for the preparation and evaluation of a polymeric gel as a new class of organic solvent absorbent. Based on our earlier organic solvent‐absorbents, the present polymeric gel exhibited high organic solvent absorbency, fast organic solvent absorption rate, and good reusability. To prepare such polymeric gel, radical polymerization was carried out with dodecyl methacrylate and butyl acrylate as comonomers, MWCNT‐ILs as crosslinking agent, and azoisobutyronitrile as initiator, providing polymeric gel in a quantitative yield. The polymeric gel synthesized under the optimized polymerization conditions absorbed 79 times the dry weight in CCl₄, 57 times in toluene, 96 in CHCl₃, and 100 times in CH₂Cl₂. The reusability of the prepared‐polymeric gel was also checked which established that the gels could be recycled and reused for at least 10 times. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3166–3172     

Zirconium oxide (NP) - ionic liquid as an efficient media for the domino Knoevenagel hetero Diels-Alder reaction with unactivated alkynes

Immobilized ZrO₂-nanopowder (NP) in ionic liquid and different organic solvents was used as a suitable Lewis-acid for the synthesis of polycyclic heterocycles which contains pyran-based skeletons. Reaction of O-propargylated salicylaldehyde with active methylene compounds in the presence of ZrO₂-NP in ionic liquid proceeds via domino Knoevenagel hetero Diels-Alder reaction of unactivated alkynes to construct the pyran skeleton. Comparison with different ionic liquids and organic solvents showed that the best results were obtained with 1-butyl-3-methylimidazolium nitrate [bmim][NO₃] because of short reaction times and high yields. Carrying out the reaction under these conditions has advantages such as: high yields, short reaction times and easy work-up.     

Simultaneous determination of trace amounts of anti-hypertensive drugs in urine using magnetic mixed hemimicelles solid-phase extraction combined with HPLC-UV

Hypertension is the leading cause of morbidity and mortality in developed and developing countries. The combination of amlodipine and carvedilol is very effective for reducing blood pressure and improving treatment compliance. Determination of drugs in biological fluids is vital in therapeutic efficacy. In the present study, a simple, rapid and efficient magnetic solid phase extraction procedure based on mixed hemimicelles is described and validated for the simultaneous determination of trace amounts of anti-hypertensive drugs in urine samples using sodium dodecyl sulfate-coated magnetite nanoparticles as extractant. Various factors, which could affect the extraction efficiency were investigated and optimized. Under the optimum conditions, the limits of detection (S/N = 3) for amlodipine and carvedilol were 5 and 2 ng/mL, respectively. The relative standard deviation for six measurements of 50 ng/mL of amlodipine and carvedilol were 4.7 and 5.2%, respectively. The developed method was applied to the analysis of patients' urine samples, and satisfactory results were obtained in the range between 81.6 and 92.7%.     

Synthesis, biological and computational study of new Schiff base hydrazones bearing 3-(4-pyridine)-5-mercapto-1,2,4-triazole moiety

A series of new Schiff base hydrazones (compounds 1-16) were synthesized by condensation reaction of 4-amino-3-(4-pyridine)-5-mercapto-1,2,4-triazole with various aldehydes and/or dialdehydes. The structure of the prepared compounds was confirmed by means of 1H NMR, 13C NMR, UV-vis, IR and elemental analyses. The all prepared compounds were assayed for antibacterial (Escherichia coli and Staphylococcus aureus) and antifungal (Candida albicans) activities by disc diffusion method. The results indicate that all tested compounds did not show any antibacterial activity against E. coli, as gram negative bacteria, and antifungal activity against C. albicans. But the compounds 2, 3, 4, 6 and 8 containing 4-Cl, 4-Me, 4-MeO, 2,4-di-Cl and 2-OH substituted phenyl moiety, respectively, showed good inhibition against S. aureus as compare to standard drugs. The structure of all biologically active compounds has also been theoretically studied by ab initio Hartree-Fock (HF) methods.     

Parallel kinetic resolution of tert-butyl (RS)-3-oxy-substituted cyclopent-1-ene-carboxylates for the asymmetric synthesis of 3-oxy-substituted cispentacin and transpentacin derivatives

tert-Butyl (RS)-3-methoxy- and (RS)-3-tert-butyldiphenylsilyloxy-cyclopent-1-ene-carboxylates display excellent levels of enantiorecognition in mutual kinetic resolutions with both lithium (RS)-N-benzyl-N-(alpha-methylbenzyl)amide and lithium (RS)-N-3,4-dimethoxybenzyl-N-(alpha-methylbenzyl)amide. A 50 : 50 pseudoenantiomeric mixture of lithium (S)-N-benzyl-N-(alpha-methylbenzyl)amide and lithium (R)-N-3,4-dimethoxybenzyl-N-(alpha-methylbenzyl)amide allows for the efficient parallel kinetic resolution of the tert-butyl (RS)-3-oxy-substituted cyclopent-1-ene-carboxylates, affording differentially protected 3-oxy-substituted cispentacin derivatives in high yield and >98% de. Subsequent N-deprotection and hydrolysis provides access to 3-oxy-substituted cispentacin derivatives in good yield, and in >98% de and >98% ee, while stereoselective epimerisation and subsequent deprotection affords the corresponding transpentacin analogues in good yield, and in >98% de and >98% ee.