Peroxidase-catalysed luminol chemiluminescence method for the determination of glutathione

A luminol chemiluminescence (CL) method was developed for the determination of glutathione (GSH). GSH was indirectly determined by measuring the amount of hydrogen peroxide formed during the Cu(II)-catalysed oxidation of GSH with oxygen. The amount of hydrogen peroxide formed was continuously measured using the Arthromyces ramosus peroxidase-catalysed luminol CL reaction. The CL intensities at maximum light emission were linearly correlated with the concentration of GSH over the range 7.5 x 10(-7)-3.0 x 10(-5) M. The detection limit for GSH was about 10 times better than that of the spectrophotometric method using Ellman reagent.     

One-pot synthetic method of unsymmetrical diorganyl selenides: reaction of diphenyl diselenide with alkyl halides in the presence of lanthanum metal

A convenient synthetic method of unsymmetrical selenides has been developed. When diphenyl diselenide was allowed to react with two equimolar amounts of primary alkyl iodides and bromides in the presence of an equimolar amount of lanthanum metal, alkyl phenyl selenides were formed in moderate to good yields. For the reaction of primary alkyl chlorides and secondary alkyl iodides, the yields of the selenides were low; however, the yields were dramatically improved by the addition of TMEDA or HMPA. A reaction pathway involving the generation of a lanthanum phenylselenolate intermediate was suggested.     

Conformational behavior on 2,2,3-trisubstituted 1,2,3,4-tetrahydroquinoline alkaloids,virantmycin, benzastatins,and their congeners,evaluated by semi-empirical molecular orbital calculations

The conformational behaviors on ring inversion between two half-chair conformers a and b in physiologically active 2,2,3-trisubstituted 1,2,3,4-tetrahydroquinoline alkaloids, virantmycin ( 1 ), benzastatin C ( 6 ), benzastatin D ( 7 ), and their congeners 2–5 , which were revealed by their nmr studies have been quantitatively evaluated by semi-empirical molecular orbital calculations (PM3). The geometries of respective half-chair conformers a and b in compounds 1–7 were optimized and it was found that their thermodynamic distributions are approximately valid in comparison with the coupling constants observed in their nmr experiments. Furthermore, these calculations estimated the energy barriers for ring inversion in compounds 1–7 in the range of ca. 4.86–11.13 kcal/mol, which were compatible with rapid interconversions between a and b at room temperature.     

Synthesis of monoglucosylated high-mannose-type dodecasaccharide,a putative ligand for molecular chaperone,calnexin, and calreticulin

Convergent and stereoselective synthetic routes to Man9GlcNAc2 (1b), alpha-Glc1M9GlcNAc2 (2b), and its stereoisomer beta-Glc1M9GlcNAc2 (3) were established. Interaction analysis of 2b with CRT was measured by 1H NMR spectroscopy, and the first NMR-based evidence for the specific binding of CRT to 2b was obtained.     

Angular dependence in the transmittance from self‐organized striped pattern of refractive indices in photopolymer

We report on a self‐organized striped pattern of refractive indices in a photopolymer and the resulting angular dependence in the transmittance as a result of the microstructure. The photopolymer plates were obtained by photoreaction of a monomer mixture placed in a space between two glass plates. The monomer mixture was prepared by mixing bifunctional methacrylate monomer, cyanoethylmethacrylate, and 2,4,6‐trimethylbenzoyldiphenylphosphine oxide as photoinitiator. After the photoreaction by uniform irradiation of UV light, the self‐organized striped pattern was observed in the crosslinked photopolymer plate by optical microscopy. Electron probe microanalysis of the cross section of the polymer plate confirms that a compositional inhomogeneity in the medium is quite small. The result suggests that the optically observed striped pattern is not due to the compositional and/or density modulation through the diffusion of monomers. We attribute the striped pattern to the crosslink density modulation and the resulting refractive‐index modulation. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 216–225, 2002     

Synthesis of bicyclic 1,3,5-triazine-2,4(3H)-diones: Reaction of amidines with diphenyl iminodicarboxylate

The preparation of bicyclic 1,3,5-triazine-2,4(3H)-diones 3 has been investigated. Diphenyl iminodicarboxylate ( 2 ) reacted smoothly with cyclic amidines to give bicyclic triazinediones in good yields.     

Graphite anode reaction in the KF2HF melt

Effects of traces of water on the graphite anode reaction have been investigated in the KF2HF melt at 100 °C. Cyclic voltammetry shows that with increasing water content from 0.01% to 0.05%, anode potentials for the formation of graphite oxide and graphite fluoride films on graphite electrodes are shifted to lower potentials. This may be ascribed to increase in the reaction of discharged oxygen with graphite and the subsequent decomposition of graphite oxide film by attack of discharged fluorine, which gives ultimately graphite fluoride film on a graphite electrode. When the water content is 0.05 %, the anode effect is thus caused in a short time by graphite fluoride film with a low surface energy. However, when it is 0.01-0.02%, a stage 4 intercalation compound of graphite, C_n⁺HF₂^- was prepared. Addition of 3-6 wt% LiF to the melt gave a stage 3 C_XF(HF)_y without occurrence of anode effect.     

Chemiluminescence of hemoglobin and identification of related compounds with the hemoglobin chemiluminescence in plasma

A low level of chemiluminescence by hemoglobin (Hb) was detected in the reaction with H2O2 and hydrogen donors such as gallic acid and catechins. The photon intensity was affected by the ferric state of Hb (methemoglobin > oxyhemoglobin), and was roughly correlated with the radical-scavenging potential of catechins. We hypothesized the reversible activation reaction of Hb as the chemiluminescence mechanism of the H2O2/gallic acid/Hb system. It is indicated that the oxidized-Hb (Hb-OOH) formation was a chemiluminescence-rate-determining step and one-electron reduction by a hydrogen donor of the compound-I-type intermediate ([.XFeIV] = O) proved a chemiluminescence-specificity-determining step. Spectral analysis showed that the photon emission from the H2O2/gallic acid/Hb system was produced without singlet oxygen generation. The concentration dependence of photon intensity suggests a high consumption ratio of H2O2 leading to protection from H2O2 toxicity. Albumin was defined as a hydrogen donor by the isolation of chemiluminescent substance in plasma using this chemiluminescence system.     

Dual-wavelength spectrophotometric determination of copper in sea-water with alpha,beta,gamma, degrees -tetrakis(1-methylpyridinium-4-yl) porphine

Copper has been determined by dual-wavelength spectrophotometry with alpha,beta,gamma, degrees -tetrakis(1-methylpyridinium-4-yl) porphine (TMPyP). The difference in absorbance at the Soret band of the copper complex (423 nm) and that of TMPyP (446 nm) was measured. Copper in a coastal sea-water sample was preconcentrated with a Chelex-100 separation in which l-cysteine was used as eluent. This combination could determine copper at the ng/ml and sub-ng/ml level.     

Characterization of synthetic adsorbents with fine particle sizes for preparative-scale chromatographic separation

Synthetic adsorbents with fine particle sizes (15-30 microm) were manufactured. These adsorbents are made of poly(styrenedivinylbenzene) and polymethacrylate, and have the same chemical structure as analytical- (5-10 microm) or industrial- (200-600 microm) grade synthetic adsorbents. Both of them have very similar porous structure to those of analytical or industrial sizes, so that they can adsorb compounds of various molecular masses. Chromatographic separation characteristics of newly manufactured fine-particle grades of synthetic adsorbents were evaluated and compared to those of analytical or industrial adsorbents. Reasonable dependency of separation performance on particle size of synthetic adsorbents was obtained. Hydraulic properties of fine-grade adsorbents had also been measured in view of column operations. Furthermore, scalability and applicability of these adsorbents for preparative-scale chromatographic separation of bioactive compounds was evaluated. Separation of soybean isoflavones and tea catechin derivatives had revealed that fine-grade synthetic adsorbents could be well applied with scalability under the same elution conditions used for analytical use. Scalability up to a 22400-fold loading amount was achieved from a small column packed with analytical-grade adsorbent used for method development to a scale-up preparative column packed with fine-grade adsorbent used for preparative purification. These results showed the usefulness of the fine-grade synthetic adsorbents for more precise purification of bioactive compounds, including pharmaceuticals and functional food additives with higher recovery.