Synthesis and DNA‐binding properties of 1,10‐phenanthroline analogues as intercalating‐crosslinkers

We synthesized a series of bis(bromomethyl)‐1,10‐phenanthrolines as novel anticancer lead compounds and examined their DNA‐binding properties. 5,6‐Bis(bromomethyl)‐1,10‐phenanthroline showed DNA intercalating activity and DNA crosslinking activity, furthermore it is stable in aqueous solution.     

Granulation of core particles suitable for film coating by agitation fluidized bed I. Optimum formulation for core particles and development of a novel friability test method

To prepare powdered medicines without bitter taste, film coating is required to cover the surface of core particles. In this study, effect of formulation and operating conditions of agitation fluidized bed on the core particle properties was investigated. In order to prevent breakage of the core particles during coating process, which sometimes causes variation of drug dissolution rate, addition of maltose syrup powder during the formulation process of the core particles was investigated. Also, a method for friability test in which the core particles were subjected to strong impact was proposed to evaluate strength of the core particles. The friability of the core particles determined by this test method correlated well with the actual friability of the particles during the coating process. Based on this result, we confirmed this novel friability test method could predict the core particle endurance during the coating process.     

Bound site of Mo atoms and its local structure in a Mo/HY catalyst characterized by extended X-ray absorption fine structure and density functional calculation

The bound site of Mo atoms and its local structure in a Mo/HY catalyst have been determined by detailed analysis of extended X-ray absorption fine structure (EXAFS). Molybdenum was introduced in the supercage of HY zeolite by cycles of saturated adsorption of Mo(CO)6 at room temperature and subsequent thermal decomposition at 573 K. Two Mo atoms per supercage were immobilized in each CVD-thermal treatment cycle. The Mo loading increased linearly with the cycles up to three cycles at saturation, where six Mo atoms were supported. Temperature-programmed decomposition of the adsorbed Mo(CO)6 was also characterized by GC, QMS, and FT-IR, respectively. The EXAFS analysis including multiple scattering based on theoretical calculations revealed that Mo bound with two oxygen atoms connects to Al, where one of the two oxygen atoms had been associated with a proton. The bound site is called the S(III)' site. The zeolite framework was significantly distorted by the introduction of low-valent Mo, resulting in isolation of the [MoO2Al] unit from the surrounding zeolite framework due to a quasi-disruption of Si-O bonds adjacent to the unit. In the mild oxidation of the low-valent Mo/HY sample two Mo=O bonds were newly formed and the position of Mo was displaced by 0.06 nm so that the distortion of zeolite framework around the Al atom was relieved. The structures were also supported by DFT calculations. This study is the first example that the position of metal cation in zeolite was determined unambiguously by the EXAFS analysis.     

Fe K‐Edge X‐ray Absorption Fine Structure Determination of γ‐Al2O3‐Supported Iron‐Oxide Species

The structure of FeO_x species supported on γ‐Al₂O₃ was investigated by using Fe K‐edge X‐ray absorption fine structure (XAFS) and X‐ray diffraction (XRD) measurements. The samples were prepared through the impregnation of iron nitrate on Al₂O₃ and co‐gelation of aluminum and iron sulfates. The dependence of the XRD patterns on Fe loading revealed the formation of α‐Fe₂O₃ particles at an Fe loading of above 10 wt %, whereas the formation of iron‐oxide crystals was not observed at Fe loadings of less than 9.0 wt %. The Fe K‐edge XAFS was characterized by a clear pre‐edge peak, which indicated that the Fe?O coordination structure deviates from central symmetry and that the degree of Fe?O?Fe bond formation is significantly lower than that in bulk samples at low Fe loading (<9.0 wt %). Fe K‐edge extended XAFS oscillations of the samples with low Fe loadings were explained by assuming an isolated iron‐oxide monomer on the γ‐Al₂O₃ surface.     

Rapid method for the determination of capsaicin and dihydrocapsaicin in Gochujang using ultra-high-performance liquid chromatography

A sensitive and specific heating block method coupled with ultra-HPLC (u-HPLC) was developed for the analysis of capsaicin in Gochujang and validated by comparing with a conventional HPLC (AOAC Method 995.03). The method validation parameters yielded good results, including linearity, precision, accuracy, and recovery. The u-HPLC separation was performed on a reversed C18 column (50 x 2 mm id, particle size 2 microm), followed by fluorescence detection (excitation 280 nm, emission 325 nm). Methanol was used as the extracting solvent, and the amount of sample taken was approximately 0.2 g; the optimum amount of extraction solvent and extraction time were 15 mL and 1 h, respectively. The recovery of capsaicin in Gochujang was more than 93%, and the LOD and LOQ of the u-HPLC analysis were 0.05 and 0.16 microg/g for capsaicin and 0.05 and 0.16 microg/g for dihydrocapsaicin. The calibration graphs for capsaicin and dihydrocapsaicin were linear from 0.2 to 10.0 microg/mL for u-HPLC. The interday and intraday precisions (RSD values) were < 6.27%.     

Studies on the biosynthesis of terrecyclic acid A II confirmation of the cyclization mechanism and hydrogen shifts using [2-2H3]acetate and [213C2H3]acetate

Feeding experiments with [2-³H₃]acetate and [2-¹³C²H₃]acetate in $\text{Aspergillus terreus}$ Thom No. 14 indicated that the hydrogen at C-2 in terrecyclic acid A is incorporated without migration from the precursor acetic acid; the results favour our group's earlier speculation for the cyclization to the tricyclic skeleton in the biosynthetic scheme.     

Manganese(II) o ctacyanotungstate(V)-based magnet containing a noncoordinated aromatic molecule

We have prepared a pillared layer magnetic material containing a noncoordinated aromatic molecule, [{MnII(pyrimidine)(H2O)}2{MnII(H2O)2}{WV(CN)8}2](pyrimidine)2.2H2O. This compound has one-dimensional channels (6.2 x 2.1 A) that are occupied by noncoordinated pyrimidine. The magnetization versus temperature plots showed the magnetic phased transition temperature (TC) was 47 K. The magnetization versus external magnetic field plots showed that the saturation magnetization (MS) value was 13.0 muB at 2 K. This MS value indicates that an antiferromagnetic interaction operates between the WV (S = 1/2) and MnII (S = 5/2) ions. The magnetic hysteresis loop showed that the coercive field (HC) was 17 G at 2 K.     

Eu(III) emission band changes caused by peripheral C-H/O hydrogen bonding

We synthesized Eu(III) and Sm(III) complexes with tridentate phosphine oxide ligands, Eu(hfa)(3)(TPPM) and Sm(hfa)(3)(TPPM) (hfa: hexafluoroacetylacetonato, TPPM: tris(diphenylphosphinyl)methane), and we then examined their luminescent properties. In the complexes the Eu(III) and Sm(III) centres were fully surrounded by low-vibrational frequency ligands, which led to relatively high emission quantum yields (Φ(Eu) = 30%, Φ(Sm) = 4.7%). The X-ray single crystal structures of the Eu(hfa)(3)(TPPM) revealed nona-coordinated Eu(III) complexes and C-H/O hydrogen bonding formations between the acidic hydrogen atom of the TPPM ligand and oxygen atoms of solvent molecules. The C-H/O hydrogen bonding slightly affected the coordination structure around the Eu(III) ion. Despite the seemingly small effect on the structural change, because the emission band profile of the (5)D(0)→(7)F(2) transition is sensitive to changes in the coordination environment of the Eu(III) complex, we observed a red shift in the emission spectral line.     

Mannose‐Binding Geometry of Pradimicin A

Pradimicins (PRMs) and benanomicins are the only family of non‐peptidic natural products with lectin‐like properties, that is, they recognize D ‐mannopyranoside (Man) in the presence of Ca²⁺ ions. Coupled with their unique Man binding ability, they exhibit antifungal and anti‐HIV activities through binding to Man‐containing glycans of pathogens. Notwithstanding the great potential of PRMs as the lectin mimics and therapeutic leads, their molecular basis of Man recognition has yet to be established. Their aggregate‐forming propensity has impeded conventional interaction analysis in solution, and the analytical difficulty is exacerbated by the existence of two Man binding sites in PRMs. In this work, we investigated the geometry of the primary Man binding of PRM‐A, an original member of PRMs, by the recently developed analytical strategy using the solid aggregate composed of the 1:1 complex of PRM‐A and Man. Evaluation of intermolecular distances by solid‐state NMR spectroscopy revealed that the C2–C4 region of Man is in close contact with the primary binding site of PRM‐A, while the C1 and C6 positions of Man are relatively distant. The binding geometry was further validated by co‐precipitation experiments using deoxy‐Man derivatives, leading to the proposal that PRM‐A binds not only to terminal Man residues at the non‐reducing end of glycans, but also to internal 6‐substituted Man residues. The present study provides new insights into the molecular basis of Man recognition and glycan specificity of PRM‐A.     

Ni‐Catalyzed [4+3+2] Cycloaddition of Ethyl Cyclopropylideneacetate and Dienynes: Scope and Mechanistic Insights

A detailed study of the Ni‐catalyzed [4+3+2] cycloaddition reaction between ethyl cyclopropylideneacetate and dienynes has been conducted, resulting in the development of a new method for the synthesis of compounds containing nine‐membered rings. We studied the reactivity of various dienynes, together with their substituent and conformational effects. The mechanism of the reaction was probed by examining the stoichiometric reactions of the Ni complexes and dienynes.