Design,synthesis and X‐ray structural studies of novel [acetonitrile‐benzyl‐3‐N‐(2, 4 dihydroxyphenylmethylene) hydrazinecarbodithioato‐κ3‐N′, S,O] nickel(ll) complex that potently inhibit cell proliferation through regulation of apoptosis related genes

Nickel is a fundamental element for healthy life for human and higher animals. For biological importance, its complexation with bioactive ligand is worth to be studied with the aim to understand its function. Using mouse peritoneal cancer model, MTT colorimetric assay and anticancer activity analysis, we examined the role of nickel(ll) complex in growth inhibition of cancer cells. A novel nickel(ll) complex was synthesized and characterized using physico‐chemical and spectroscopic techniques. The study indicated that both the ligand and complex were capable of inhibiting Ehrlich Ascites Carcinoma (EAC) cells growth by 28.21% and 44.52%, respectively, when administered 0.3 mg/kg/day body weight intraperitoneally for five consecutive days in Swiss Webstar mice. Determination the LD₅₀ of the complex (55 mg/kg) allowed adjusting the dose as 2.75 mg/kg and upon administration, inhibition increased to 69.36%. The ligand and complex have shown an inhibitory effect in the range of 4.86%–67.3% and 6.1%‐ 89.37%, respectively, against EAC cells (concentration range of 31.25–500 μg/ml) in RPMI‐1640 medium as determined by MTT colorimetric assay. Apoptotic cell morphological alteration was determined through optical and fluorescence microscopy. Up regulation of P⁵³, Bax, Cas‐8, Cas‐3 and Fas and down regulation of NF‐kB and Bcl‐2 gene expression were observed in the cells treated with the nickel(ll) complex for five consecutive days. In conclusion, the newly synthesized nickel(ll) complex has shown anti‐proliferative activity and can further be optimized to be used as a lead molecule for anticancer drug.     

Submicrometer tomographic resolution examined using a micro-fabricated test object

To estimate the spatial resolution of microtomographs, a test object on the submicrometer scale was prepared by focused ion beam milling and subjected to microtomographic analysis. Since human tissues are composed of cells and extracellular matrices with micrometer and submicrometer structures, it is important to investigate the three-dimensional spatial resolution of microtomographs used to visualize microstructures of human tissues. The resolutions along the direction within the tomographic slice plane (in-plane resolution) and perpendicular to it (through-plane resolution) were determined from the modulation transfer function of square-wave patterns. The in-plane resolution was estimated to be 1.2 μm from the modulation transfer function of the non-zoom image. In contrast, the zoom image gave the in-plane resolution of 0.8 μm. This in-plane resolution is comparable to the through-plane resolution, which was estimated to be 0.8 μm. Although the two-dimensional radiographs were taken with the pixel width of half the X-ray optics resolution, these three-dimensional resolution analyses indicated that the zoom reconstruction should be performed to achieve the in-plane resolution comparable to the X-ray optics resolution. The submicrometer three-dimensional analysis was applied in the structural study of human cerebral tissue stained with high-Z elements and the obtained tomograms revealed that the microtomographic analysis allows visualization of the subcellular structures of the cerebral tissue.     

Solvation number and conformation of N,N-dimethylacrylamide and N,N-dimethylpropionamide in the coordination sphere of the cobalt(II) ion in solution studied by FT-IR and FT-Raman spectroscopy.

The solvation number and conformation of N,N-dimethylacrylamide (DMAA) in the coordination sphere of the cobalt(II) ion in solution were studied, and compared with those of N,N-dimethylpropionamide (DMPA) by means of FT-Raman and FT-IR spectroscopy. Both solvents are present as either the planar cis or nonplanar staggered conformer in equilibrium, and the former is more stable in the bulk. As these solvents solvate the metal ion through the carbonyl O atom of the acryl (DMAA) or propionyl (DMPA) group, the solvation structure around the metal ion is highly congested to reduce the solvation number and/or to lead to a conformational geometry change of solvent. It turns out that the solvation number of the cobalt(II) ion is 4 for both DMAA and DMPA at 298 K, and that DMPA changes its conformation upon solvation, whereas DMAA hardly changes. The enthalpy of conformational change DeltaH degrees for DMPA is 5 kJ mol(-1) in the bulk, and is -9 kJ mol(-1) in the coordination sphere of the cobalt(II) ion. On the other hand, the DeltaH degrees value for DMAA is 9 kJ mol(-1) in the bulk.     

Ligularidine,a new pyrrolizidine alkaloid from Ligularia dentata

The structure of a new macrocyclic pyrrolizidine alkaloid, ligularidine(1), having significantly high mutagenic activity was elucidated and the configurations of the necic acid and its enantiomer reported by Edwards² were also determined.     

Ischemic change of organic acids in kidney

Organic acids in rabbit renal tissue biopsy were analyzed by capillary column gas chromatography--mas s spectrometry. The change of these organic acids under ischemic conditions was determined over 60 min after clamping the renal artery and vein. The results showed that lactic acid, glycolic acid, 2-hydroxybutyric acid, 3-hydroxypropionic acid, 2-methyl-glyceric acid, glyceric acid and malic acid increased at 4 and 6 min after clamping, but then decreased at 15 min. Glycerol increased 2 min after clamping and then decreased. However, 3-deoxyaldonic acids of 3-deoxytetronic acid, 3-deoxy-2-C-hydroxymethyltetronic acid and 3-deoxypentonic acid decreased in the renal tissue biopsy from 2 min after clamping.     

The packing structure of side chains of liquid-crystalline side-chain polymers before and during heat treatment

Six varieties of liquid-crystalline side-chain polymers, poly (cholesteryl ω-(methacryloyloxy)alkanoates) (p-ChMO-n, n = 1,2,3,4,5,7, the carbon number of the alkyl chain), were studied by differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS). On and after the first cooling run from the isotropic state, these polymethacrylates gave the same smectic phase. However, on the first heating run for virgin samples, unique phenomena were observed, similar to those frequently observed on the first heating run for thermotropic liquidcrystalline polymers. The thermal properties of the first heating run for these six polymers showed different tendencies between pChMO-n (n-1-3) and pChMO-n (4-7). Although the DSC curve of pChMO-n (n = 4, 5 and 7) exhibited the melting and clearing points on the first heating run, the DSC curve of pChMO-n (n = 1,2 and 3) exhibited an exothermal peak between the glass transition and the clearing point on the first heating run. This difference, probably due to the difference in the spacer length of these polymers, was investigated quantitatively by small-angle X-ray scattering by which the micro-change of the packing structure of the side chains of the polymers was traced.     

Solvation structure of magnesium,zinc, and alkaline earth metal ions in N,N‐dimethylformamide,N,N‐dimethylacetamide,and their mixtures studied by means of Raman spectroscopy and DFT calculations—Ionic size and electronic effects on steric congestion

The solvation structure of magnesium, zinc(II), and alkaline earth metal ions in N,N‐dimethylformamide (DMF) and N,N‐dimethylacetamide (DMA), and their mixtures has been studied by means of Raman spectroscopy and DFT calculations. The solvation number is revealed to be 6, 7, 8, and 8 for Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺, respectively, in both DMF and DMA. The δ (O C N) vibration of DMF shifts to a higher wavenumber upon binding to the metal ions and the shift Δν(= ν_bound − ν_free) becomes larger, when the ionic radius of the metal ion becomes smaller. The ν (N CH₃) vibration of DMA also shifts to a higher wavenumber upon binding to the metal ions. However, the shift Δν saturates for small ions, as well as the transition‐metal (II) ions, implying that steric congestion among solvent molecules takes place in the coordination sphere. It is also indicated that, despite the magnesium ion having practically the same ionic radius as the zinc(II) ion of six‐coordination, their solvation numbers in DMA are significantly different. DFT calculations for these metalsolvate clusters of varying solvation numbers revealed that not only solvent–solvent interaction through space but also the bonding nature of the metal ion plays an essential role in the steric congestion. The individual solvation number and the Raman shift Δν in DMF–DMA mixtures indicate that steric congestion is significant for the magnesium ion, but not appreciable for calcium, strontium, and barium ions, despite the solvation number of these metal ions being large. Copyright © 2006 John Wiley & Sons, Ltd.     

Polyhydroxybutyrate production from carbon dioxide by cyanobacteria

Genetic characterization and enhancement of polyhydroxybutyrate (PHB) accumulation in cyanobacteria were investigated for efficient PHB production from CO₂. The genome DNAs in the PHB-accumulating strains Synechococcus sp. MA19 and Spirulina platensis NIES46 retained the highly homologous region to phaC of Synechocystis PCC6803, whereas low homology was detected in the nonaccumulating strains Synechococcus sp. PCC7942 and Anabaenacylindrica NIES19. Synechococcus sp. MA19, which accumulates PHB up to 30% of dry cell weight from CO₂ as the sole carbon source, was mutated by insertion of transposon Tn5 to enhance the PHB accumulation. Genetic and physiological analysis of the mutant indicated that decreased phosphotransacetylase activity could trigger an increase of acetyl coenzyme A leading to enhancement of PHB accumulation. PHB synthase in Synechococcus sp. MA19 was probably attached to thylakoid membrane since PHB granules were associated with pigments. A genetically engineered cyanobacteria retaining soluble PHB synthase from Ralstonia eutropha accumulated pigment-free PHB granules, which is an advantage for the purification of PHB.     

A C4N4 Diaminopyrimidine Fluorophore

A new scaffold for producing efficient organic fluorescent materials was identified: 2,5-diamino-4,6-diarylpyrimidine featuring a C4N4 elemental composition. Single-step installation of two aryl groups at the 4,6-positions of the pyrimidine core delivered fluorescent organic materials in a modular fashion. A range of fluorescent compounds with distinct absorption/emission properties was readily accessed by changing the aromatic attachments. A generally high absorption coefficient and quantum yield were observed, including C4N4 derivatives that could fluoresce even in the solid state. The two amino groups at the 2,5-positions of the pyrimidine were essential for intense fluorescence with a large Stokes shift, which was corroborated by structural relaxation to a p-iminoquinone-like structure in the excited state. Besides live-cell imaging capabilities, fluorescent labeling of a protein involved in autophagy elucidated a new protein–protein interaction, supporting potential utility in bioimaging applications.