Novel synthesis of zerumbone-pendant derivatives and their biological activity

Zerumbone 1, having powerful latent reactivity and containing two conjugated double bonds and a double conjugated carbonyl group is the major component of the essential oil of wild ginger, Zingiber zerumbet Smith. The conjugation system plays an important role in the expression of biological activity. N-Bromosuccinimide (NBS) reaction of 1 gave high reactive intermediate 2 with an exo-methylene group, which was obtained from 1 quantitatively. Treatment of 2 with nucleophiles gave various zerumbone-pendant derivatives, including C–H, C–O, C–N, and C–C bond formation, maintaining the conjugation system through S_N2′-type reaction. Almost all zerumbone-pendant derivatives showed a good value of IC₅₀ against the suppressive effect of NO generation. Among them, amine derivative 5, binding with 2 mol of zerumbone, showed the strongest activity (IC₅₀: 0.24 μM).     

Synthesis of fused tetrahydropyrans by hydroalkoxylation of δ-hydroxy allenes

Fused tetrahydropyrans were synthesized by silver(I)- and mercury(II)-mediated intramolecular hydroalkoxylations of δ-hydroxy allenes installed on a tetrahydropyran template. Cyclization of simple allenes was promoted by silver perchlorate to afford vinyl-substituted trans-fused bis-tetrahydropyrans, whereas cyclization of methyl-substituted allenes at the internal allenic carbon atom was achieved more effectively with a catalytic amount of mercuric triflate rather than with silver salts.     

Efficient lookup table using a linear function of inverse distance squared

The major bottleneck in molecular dynamics (MD) simulations of biomolecules exist in the calculation of pairwise nonbonded interactions like Lennard‐Jones and long‐range electrostatic interactions. Particle‐mesh Ewald (PME) method is able to evaluate long‐range electrostatic interactions accurately and quickly during MD simulation. However, the evaluation of energy and gradient includes time‐consuming inverse square roots and complementary error functions. To avoid such time‐consuming operations while keeping accuracy, we propose a new lookup table for short‐range interaction in PME by defining energy and gradient as a linear function of inverse distance squared. In our lookup table approach, densities of table points are inversely proportional to squared pair distances, enabling accurate evaluation of energy and gradient at small pair distances. Regardless of the inverse operation here, the new lookup table scheme allows fast pairwise nonbonded calculations owing to efficient usage of cache memory. © 2013 Wiley Periodicals, Inc.     

Accurate measurement of uranium isotope ratios in soil samples using thermal ionization mass spectrometry equipped with a warp energy filter

A chemical and mass-spectrometric procedure for uranium isotopic analysis using a thermal ionisation mass spectrometer equipped with a Wide Aperture Retardation Potential energy filter has been developed and applied to uranium isotopic measurements for various soil samples. Soil samples were digested using a microwave digestor. Uranium was isolated from soil samples by the chemical separation procedure based on the use of anion-exchange resin and UTEVA extraction chromatography column. The isotope ratios were measured for two certified reference materials by using a VG Sector 54-30 thermal ionisation mass spectrometer in dynamic mode with Faraday cup and Daly ion counting system. Replicates of standard reference materials showed excellent analytical agreement with established values supporting the reliability and accuracy of the method. Precision of the ²³⁵U/²³⁸U ratio was achieved by a correction factor of 0.22% amu as a function of ion-beam intensity with sample loads of around 250?ng of U. The resulting reproducibility for standards and soil samples was better than 0.2% at two standard deviations (SD). Uranium isotopic compositions have been determined in several reference soil samples such as Buffalo river sediment, NIST 2704, river sediment SRM 4350b and ocean sediment NIST-4357 and a Chernobyl soil sample. There was a significant deviation from the natural uranium in comparison with Chernobyl soil samples.     

Characterization of flower-inducing compound in Lemna paucicostata exposed to drought stress

A flower-inducing compound, LDS1, was isolated from a free-floating aquatic plant, Lemna paucicostata. The chemical structure and the absolute stereochemistry of LDS1 were determined as (9R,13R,11E,15Z)-9,13-dihydroxy-10-oxooctadeca-11,15-dienoic acid for its most abundant diastereomer. LDS1 was enzymatically produced when the plant was exposed to drought stress, and induced flowering at a concentration of 10 nM.     

Dibenzo[a,f]perylene Bisimide: Effects of Introducing Two Fused Rings

Perylene bisimides (PBIs) are fascinating dyes with various potential applications. To study the effects of introducing a dibenzo‐fused structure to the perylene moiety, π‐extended PBI derivatives with a dibenzo‐fused structure at both of the a and f bonds were synthesized. The twisted structure was characterized by X‐ray crystal structure analysis. In the cyclic voltammograms, the dibenzo[a,f]‐fused PBI showed a reversible oxidation wave at much less positive potential, relative to a dibenzo[a,o]‐fused PBI derivative. These data indicated that two ring fusions at both sides of a naphthalene moiety, which construct a tetracene core, effectively raise the HOMO level compared to fusion of one ring at each naphthalene moiety (two anthracene cores). The dibenzo[a,f]‐fused PBI derivative showed an absorption band at 735 nm with a shoulder band reaching 900 nm.     

Complex formation of light and heavy lanthanides with DGA and DOODA,and its application to mutual separation in DGA–DOODA extraction system

We studied the stepwise formation constants (β) of water-soluble diglycolamide (DGA) and dioxaoctanediamide (DOODA) for the mutual separation of Ln in a solvent extraction system. TODGA (N,N,N?,N?-tetraoctyl-diglycolamide) and DOODA(C8) (N,N,N?,N?-tetraoctyl-dioxaoctanediamide) exhibit opposite behaviors in extracting both light and heavy Ln through Ln-patterns. Metal complexes of two- and three-folding with water-soluble DOODA and DGA, respectively, were found, and each β value was calculated using distribution ratios. Taking β, their distribution ratio, D, and separation factor, SF, values into consideration, the suitable separation conditions (aqueous phase: 30 mM DOODA(C2) in 1 M HNO₃; organic phase: 0.1 M TODGA in n-dodecane) of multistage extraction (10?×?10 extraction using aqueous and organic phases, including one sample solution) were determined. In this study, La, Pr, and Nd were mainly present in the aqueous phase, whereas Sm–Dy existed in the organic phase. Although these two groups can be easily separated into two phases, the resolution, Rs, values provide for little mutual separation between La–Nd and Sm–Dy under the present conditions.

     

Bipolar Electrode-based Electrochromic Devices for Analytical Applications – A Review

Bipolar electrode-based (BPE-based) electrochromic devices have garnered increasing attention in the past decade. These BPE-based electrochromic devices have been used for analytical health monitoring, point-of-care (POC) diagnostics, and chemical sensing. In this review, we highlight recent progress made regarding BPE-based electrochromic devices constructed for these analytical applications. Various, available electrochromic materials are summarized in the first section, after which the different device types (e. g., paper-based and self-powered) are discussed. Biological- and chemical-based analytical demonstrations of these devices are then reviewed. Finally, we conclude this review with a perspective on the future developments of BPE-based electrochromic devices in analytical applications.     

Garcinielliptone G from Garcinia subelliptica Induces Apoptosis in Acute Leukemia Cells

Cytotoxicity and apoptosis-inducing properties of compounds isolated from Garcinia subelliptica leaves were investigated. The hexane-soluble portion of MeOH extracts of G. subelliptica leaves that showed cytotoxic activity was separated to yield seven compounds 1–7. Chemical structure analysis using NMR spectroscopy and mass spectrometry confirmed that compound 1 was canophyllol, and compounds 2–7 were garcinielliptones N, O, J, G, F, and garcinielliptin oxide, respectively. Among them, garcinielliptone G (5) showed growth inhibition by causing apoptosis in THP-1 and Jurkat cells derived from human acute monocytic leukemia and T lymphocyte cells, respectively. Apoptosis induced by garcinielliptone G (5) was demonstrated by the detection of early apoptotic cells with fluorescein-labeled Annexin V and increases in cleaved caspase-3 and cleaved PARP protein levels. However, the addition of caspase inhibitor Z-VAD-FMK did not affect growth arrest or apoptosis induction. These results suggest that garcinielliptone G (5) can induce both caspase-3 activation and caspase-independent apoptosis. Therefore, garcinielliptone G (5) may be a potential candidate for acute leukemia treatment.     

Structural,Magnetic and Catalytic Properties of a New Vacancy Ordered Perovskite Type Barium Cobaltate BaCoO2.67

A new vacancy ordered, anion deficient perovskite modification with composition of BaCoO_2.67 (Ba₃Co₃O₈□₁) has been prepared via a two-step heating process. Combined Rietveld analysis of neutron and X-ray powder diffraction data shows a novel ordering of oxygen vacancies not known before for barium cobaltates. A combination of neutron powder diffraction, magnetic measurements, and density functional theory (DFT) studies confirms G-type antiferromagnetic ordering. From impedance measurements, the electronic conductivity of the order of 10⁻⁴ S cm⁻¹ is determined. Remarkably, the bifunctional catalytic activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is found to be comparable to that of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3–y, confirming that charge-ordered anion deficient non-cubic perovskites can be highly efficient catalysts.