Organometallic Rotaxanes with a Triazole Group in the Axle Component and Their Behavior as Ligands of PtII Complexes

Two ferrocenylmethyl ammonium salts were used as axle components of pseudorotaxanes with dibenzo[24]crown‐8. The pseudorotaxane with an alkyne terminal group in the axle component underwent a Cu‐catalyzed Huisgen coupling reaction (click reaction) with an alkyl azide to afford cationic [2]rotaxanes with a triazole group in the axle molecule. The rotaxane reacted with Ac₂O to produce neutral rotaxanes with an amide group in the axle component. Both cationic and neutral rotaxanes were treated with K[PtCl₃(CH₂?CH₂)] to form the Pt^II‐containing rotaxanes.     

Transient pore dynamics in pH-responsive liquid membrane

We have investigated the transient pore dynamics in a chemically destabilized liquid membrane in buffer solutions at macroscopic scale. A hole opened and closed repeatedly in response to pH in the surrounding media when the concentration of surfactant in the liquid membrane was sufficiently high to form emulsion at equilibrium and the membrane was larger than a critical value. The analysis of pore dynamics allowed us to estimate some physicochemical properties such as membrane tension, line tension, and membrane viscosity.     

Determination of ethylenediaminetetraacetic acid in sea water by solid-phase extraction and high-performance liquid chromatography

The chelating agent EDTA is widely used, and as a result is showing up widely in the aquatic environment. Here we describe a preconcentration procedure for measuring EDTA concentration in sea water samples by HPLC. The procedure consists of forming an Fe(III) complex followed by solid-phase extraction using an activated carbon cartridge. After the preconcentration, EDTA was quantified by HPLC with ultraviolet detection (260 nm). The enrichment permitted the determination of EDTA at concentrations as low as 1 nM. Good recoveries were obtained for both brackish and full-strength sea water with high repeatability (RSD < 6%). The method was applied to sea water samples taken from near the mouth of the Oyabe River in Japan.     

Ultrafast excited state dynamics of spirilloxanthin in solution and bound to core antenna complexes: Identification of the S∗ and T(1) states

Ultrafast excited state dynamics of spirilloxanthin in solution and bound to the light-harvesting core antenna complexes from Rhodospirillum rubrum S1 were investigated by means of femtosecond pump-probe spectroscopic measurements. The previously proposed S? state of spirilloxanthin was clearly observed both in solution and bound to the light-harvesting core antenna complexes, while the lowest triplet excited state appeared only with spirilloxanthin bound to the protein complexes. Ultrafast formation of triplet spirilloxanthin bound to the protein complexes was observed upon excitation of either spirilloxanthin or bacteriochlorophyll-a. The anomalous reaction of the ultrafast triplet formation is discussed in terms of ultrafast energy transfer between spirilloxanthin and bacteriochlorophyll-a.     

Mineral composition of frozen taro for determination of geographic origin

The mineral composition of frozen food of taro [Colocasia esculenta (L.) Schott] was analyzed to categorize the geographical production place of taro. The concentrations of Co and H₂PO₄ ⁻ were found to be useful to separate the producing place between Japan and China. The analysis was performed by instrumental neutron activation analysis (INAA) and ion chromatography (IC). In the case of INAA, the samples were dried and sealed in a vinyl bag and irradiated with thermal neutrons from JRR3M, installed at Japan Atomic Energy Agency (JAEA). The activated samples were cooled down for a few weeks and the elements (Co, Cr, Fe, Rb, Zn) were determined. Cobalt concentration of frozen taro from China was higher than that from Japan. The tendency was the same in the fresh sample of taro. When concentration of H₂PO₄ ⁻ of frozen sample was measured, taro from Japanese product was higher than that of Chinese one, contrary to fresh sample. This result might be caused by the leakage of H₂PO₄ ⁻ during freezing process, indicating that we should be careful to apply the discrimination indicators. In addition to Co, there was a significant difference of Rb and Fe concentrations between frozen taro from Japan and China.     

Synthesis of oxovanadium complexes and their apoptosis-inducing activity in leukemia cells

Vanadium complexes with different ligands were synthesized and evaluated for antiproliferative activity on U937 cells. The alkyl chain length of the ligands affected the antiproliferative activity, and two complexes-3b and 4-exhibited strong activities with IC(50) values of 6.02 and 3.90 μM respectively. Annexin V staining and DNA ladder formation indicated that these complexes induced apoptosis in U937 cells.     

Structural Study on Water-induced Phase Transitions of Poly(ethylene imine) as Viewed from the Simultaneous Measurements of Wide-Angle X-ray Diffractions and DSC Thermograms

Thermal behavior of poly(ethylene imine) [PEI] has been studied using simultaneous WAXD/DSC measurement system. PEI exhibits water-induced and thermally-induced phase transitions among four kinds of crystalline hydrates: anhydrate (EI/water = 1/0), hemihydrate (1/0.5), sesquihydrate (1/1.5), and dihydrate (1/2). The chain conformation changes from a double helix in the anhydrate to a planar zigzag form in the three hydrates. The anhydrate melts at 60 °C while the hydrates melt differently in the temperature region of 70–110 °C. By means of the simultaneous WAXD/DSC measurements, complex DSC thermograms of PEI hydrates were characterized on the basis of X-ray diffractions obtained concurrently.     

Biomimetic transformation of dehydrocurdione into curcumenol and isocurcumenol and their stereochemistries

Dehydrocurdione, a sesquiterpene isolated from $\text{Curcuma zedoaria}$, was converted to curcumenol, isocurcumenol or new spirolactones in a highly selective manner and their absolute configurations were determined.     

A novel synthesis of benzo- and indolo[a]quinolizidines by intramolecular diels-alder reaction of l-azadienes

Intramolecular Diels-Alder reaction of l-azadienes was conducted by heating the α,β-unsaturated amides (2a ～ d and 6) in the presence of trimethyl- chlorosilane, triethylamine and zinc chloride to give benzo- and indolo[a]- quinolizidines (5a ～ e and 7).     

Assay of Angiotensin I-converting Enzyme-inhibiting Activity Based on the Detection of 3-Hydroxybutyrate with Water-soluble Tetrazolium Salt.

A newly synthesized substrate, 3-hydroxybutyrylglycyl-glycyl-glycine (3HB-GGG), was applied to the assay of ACE-inhibiting activity to overcome the smaller selectivity and sensitivity of the conventional method. In this study, an ACE-inhibiting assay was improved by the use of a water-soluble tetrazolium salt, 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate sodium salt (WST-1), for the detection of 3-hydroxybutyrate, derived from 3HB-GGG. The optimized conditions were as follows: 0.333 mM NAD(+), 0.333 mM WST-1, 0.1 mM EDTA, 0.633 U ml(-1) diaphorase, and 0.700 U ml(-1) 3-hydroxybutyrate dehydrogenase. The developed assay was efficiently applicable to evaluate the ACE-inhibiting activity of practical ACE inhibitors.