Determination of purine nucleosides and their bases by high-performance liquid chromatography using co-immobilized enzyme reactors

A selective and sensitive assay of inosine, guanosine, hypoxanthine, guanine and xanthine by high-performance liquid chromatography with immobilized enzyme reactors was developed. The separation was achieved on a Capcell Pak C18 column (15 cm x 0.46 cm I.D.) with a mobile phase of 0.1 M phosphate buffer (pH 8.0) containing 7 mM sodium 1-hexanesulphonate and 0.1 mM p-hydroxyphenylacetic acid. The fluorimetric detection of hydrogen peroxide using immobilized peroxidase and p-hydroxyphenylacetic acid was applied to the assay of these compounds, which were oxidized to yield hydrogen peroxide in the presence of immobilized enzyme (purine nucleoside phosphorylase, guanase and xanthine oxidase). Enzyme reactions occurred sufficiently without post-column addition of reagents. Enzymes that catalysed the conversion of purine compounds were co-immobilized on aminopropyl controlled-pore glass packed in stainless-steel tubing. The detection limits were 30-200 pg per injection.     

Deposition of gamma-emitting nuclides in Japan after the reactor-IV accident at Chernobyl'

The wet and dry deposition of gamma-emitting nuclides are presented for Tsukuba and eleven stations in Japan following the nuclear reactor accident at Chernobyl'. In Japan fallout from the reactor at Chernobyl' was first detected on May 3, 1986, a week after the accident. Abruptly high radioactive deposition, which mainly consists of¹³¹I,¹³²I,¹⁰³Ru,¹³⁷Cs and¹³⁴Cs, was observed in early May. The cumulative amount of¹³¹I,¹⁰³Ru and¹³⁷Cs in May at Tsukuba were 5854±838 Bq·m^–2, 364±54 Bq·m^–2 and 130±26 Bq·m^–2 (decay was corrected to April 26), respectively. The monthly¹³⁷Cs deposition in May corresponds to 2.5% of the cumulative¹³⁷Cs deposition during the period from 1960 through 1982. Most of the Chernobyl' radioactivities, especially¹³¹I, are scavenged from the atmosphere by the wet removal process.     

Serum thymidine kinase activity of various cancer and HBV positive liver diseases

Clinical utility of determination of serum deoxythymidine kinase (TK) activity is described. It is well known that elevated TK level is observed in leukemia and other malignant diseases, or some viral infectious diseases. The TK activity was assayed on normal subjects, hepatitis B virus (HBV) positive liver diseases and various cancer by a newly developed high sensitive method, radio enzyme assay (REA) utilizing 125I-iododeoxyuridine as the substrate. Measurement of TK activity by the REA is revealed to be useful for "the marker of DNA metabolism anomaly" in leukemia, etc.     

Isolation of key intermediates during formation of oolongtheanins

Oolongtheanin-3′-O-gallate (2b) was obtained by treatment of (−)-EGCg (1d) with CuCl₂. This transformation was achieved over three steps, with the isolation of two intermediates; their chemical structures were determined through derivatization reactions, MS, and 1D/2D NMR techniques. One intermediate was identified as dehydrotheasinensin A (3); the other was identified as the novel dimer pro-oolongtheanin-3′-O-gallate (6). Compound 3 was converted to 6 by heating in aprotic solvent, and compound 6 was converted to 2b by addition of water.     

Thermodynamically Stable o-Quinodimethane: Synthesis,Structure, and Reactivity

Thermal isomerization of cyclobutaphenanthrene to o-quinodimethane was investigated. Sterically congested substituents or electron-donating substituents on the four-membered ring promoted the ring-opening, affording o-quinodimethane in a relatively stable form. Isolation of the newly prepared o-quinodimethane allowed its structural elucidation and investigation of its potential reactivities. Dual [4+2] cycloaddition of an aryne and o-quinodimethane afforded tetrabenzopentacene, demonstrating the synthetic application of the isolated compound.     

Chemical speciation of plutonium in seawater

Concentrations of particulate and dissolved plutonium in seawater were determined together with strong organic ligands (SOL) in particulate matter (PM). The concentration of particulate 239,240Pu in surface waters of the Western North Pacific ranged from 0.03 to 0.3 mBq m(-3) during the period from 1987 to 1997. The percentage of particulate Pu to total Pu in seawater was less than 10% in surface waters, whereas its portions were less than 1% in deep waters. In order to characterize particulate Pu in seawater, the relationships between particulate Pu, dissolved Pu and SOL concentrations in surface PM were examined. The result reveals that particulate Pu was linearly related to the SOL concentration independent of dissolved Pu concentration. Mass balance analysis suggests that a dominant chemical form of Pu in surface PM, which may exist as Pu(IV), is a complex with strong organic ligands in PM.     

Transport of monosaccharides through a liquid membrane mediated by lipophilic alkaline earth metal complexes

Lipophilic alkaline earth metal complexes, prepared from the corresponding metal hydroxides and phosphoric acid diesters, are quite effective for the transport of some monosaccharides, especially ribose, across a chloroform liquid membrane under neutral conditions.     

Ab initio inter-radical potential for p-phenylenediamine radical cation dimer

Ab initio molecular orbital calculations were carried out to investigate the inter-radical interaction of the paired p-phenylenediamine radical cations in the singlet state. After initial optimization of the dimer in the parallel sandwich (D2h) and parallel displaced (Cs) configurations at the B3LYP/6-31G* theoretical level, the MP2/6-31G* and B3LYP/6-31G* single energies of the dimer were calculated as a function of the inter-radical distance R. The depths of the potential minima near R = 3.2 A were estimated to be in the order of the hydrogen bonding energy, assuming that the electrostatic contribution between the cations is canceled out by the attractive contributions due to the counter anions on the aspect of a simple electrostatic model. This can be related to the indications of the cation dimer formation in solution in the presence of counter anions at a low temperature reported previously in the literature by resonance Raman and electronic absorption spectra. The inter-radical (Raman active) frequencies of the dimer were calculated, one of which corresponds to the reported value at 161 cm(-1) observed in the resonance Raman spectrum in ethanol at 200 K by Yokoyama and Maeda (Chem. Phys. Lett. 48 (1977) 59).     

Polymeric fibers and microporous films by photo‐crosslinking of triphenylene‐derived liquid crystals

Two series of photoreactive discotic liquid crystals consisting of a triphenylene core and six cinnamate units with one ( TPC1 _n ) or two ( TPC2 _n ) n‐alkoxy groups (C _nH_2n+1O; n = 10–14), respectively, as peripheral groups are synthesized. Both of them are polymerized into fibers up to 2 mm long by UV irradiation in liquid paraffin in the columnar LC temperature ranges. The fiber structures seem to be preconstructed in liquid paraffin. In addition, TPC2 _n are shown to form microporous films up to 15 μm in diameter by simply casting the solutions of some solvents followed by drying for several minutes in air at room temperature. Photoirradiation of the films in the LC temperature range converts them to polymeric ones while preserving the microporous and hexagonally ordered structure. From comparison with TPC1 _n and the hydrogenated derivative of TPC2 ₁₂ , the porous film‐forming property is suggested to result from the combination of the double bond of the cinnamoyl group and the two long alkoxy chains on the phenyl ring. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 605–612