Detection of dideuterium in diprotium gas at infinitesimal concentration using a trace reduction detector

An analyzer able to detect extremely small concentrations of dideuterium in diprotium gas was developed. To examine its performance, four gas samples of pure diprotium with dideuterium concentrations of 0.25, 0.5, 1, and 5 cm(3)/m(3) were measured using the analyzer, and peak areas and retention times from 18 chromatograms were determined. Results indicated that the peaks were distributed within a relative standard deviation of approximately 15% and a linear correlation existed between peak area and concentration. Retention times were stable, showing a relative standard deviation of 1% with repeated tests and having no correlation with concentration of the four gas samples.     

Deuterium and oxygen-18 determination of microliter quantities of a water sample using an automated equilibrator

We describe a modified version of the equilibration method and a correction algorithm for isotope ratio measurements of small quantities of water samples. The deltaD and the delta(18)O of the same water sample can both be analyzed using an automated equilibrator with sample sizes as small as 50 microL. Conventional equilibration techniques generally require water samples of several microL. That limitation is attributable mainly to changes in the isotope ratio ((18)O/(16)O or D/H) of water samples during isotopic exchange between the equilibration gas (CO(2) or H(2)) and water, and therefore the technique for microL quantities of water requires mass-balance correction using the water/gas (CO(2) or H(2)) mole ratio to correct this isotopic effect. We quantitatively evaluate factors controlling the variability of the isotopic effect due to sample size. Theoretical consideration shows that a simple linear equation corrects for the effects without determining parameters such as isotope fractionation factors and water/gas mole ratios. Precisions (1-sigma) of 50-microL meteoric water samples whose isotopic compositions of -1.4 to -396.2 per thousand for deltaD are +/-0.5 to +/-0.6 per thousand, and of -0.37 to -51.37 per thousand for delta(18)O are +/-0.01 to +/-0.11 per thousand.     

Elucidation of Chemical Interactions between Crude Drugs Using Quantitative Thin-Layer Chromatography Analysis

To elucidate the interactions between crude drugs in Kampo medicines (traditional Japanese medicines), it is important to determine the content of the constituents in a cost-effective and simple manner. In this study, we quantified the constituents in crude drug extracts using thin-layer chromatography (TLC), an inexpensive and simple analytical method, to elucidate the chemical interactions between crude drugs. We focused on five crude drugs, for which quantitative high-performance liquid chromatography (HPLC) methods are stipulated in the Japanese Pharmacopoeia XVIII (JP XVIII) and compared the analytical data of HPLC and TLC, confirming that the TLC results corresponded with the HPLC data and satisfied the criteria of JP XVIII. (Z)-ligustilide, a major constituent in Japanese Angelica Root, for which a method of quantification has not been stipulated in JP XVIII, was also quantitatively analyzed using HPLC and TLC. Furthermore, Japanese Angelica Root was combined with 26 crude drugs to observe the variation in the (Z)-ligustilide content from each combination by TLC. The results revealed that combinations with Phellodendron Bark, Citrus Unshiu Peel, Scutellaria Root, Coptis Rhizome, Gardenia Fruit, and Peony Root increased the (Z)-ligustilide content. Quantifying the constituents in crude drug extracts using the inexpensive and simple TLC method can contribute to elucidating interactions between crude drugs in Kampo medicines, as proposed by the herbal-pair theory.     

Enhanced Cytotoxic Effects of Arenite in Combination with Active Bufadienolide Compounds against Human Glioblastoma Cell Line U-87

The cytotoxicity of a trivalent arsenic derivative (arsenite, As^III) combined with arenobufagin or gamabufotalin was evaluated in human U-87 glioblastoma cells. Synergistic cytotoxicity with upregulated intracellular arsenic levels was observed, when treated with As^III combined with arenobufagin instead of gamabufotalin. Apoptosis and the activation of caspase-9/-8/-3 were induced by As^III and further strengthened by arenobufagin. The magnitude of increase in the activities of caspase-9/-3 was much greater than that of caspase-8, suggesting that the intrinsic pathway played a much more important role in the apoptosis. An increase in the number of necrotic cells, enhanced LDH leakage, and intensified G₂/M phase arrest were observed. A remarkable increase in the expression level of γH2AX, a DNA damage marker, was induced by As^III+arenobufagin. Concomitantly, the activation of autophagy was observed, suggesting that autophagic cell death associated with DNA damage was partially attributed to the cytotoxicity of As^III+arenobufagin. Suppression of Notch signaling was confirmed in the combined regimen-treated cells, suggesting that inactivation of Jagged1/Notch signaling would probably contribute to the synergistic cytotoxic effect of As^III+arenobufagin. Given that both As^III and arenobufagin are capable of penetrating into the blood–brain barrier, our findings may provide fundamental insight into the clinical application of the combined regimen for glioblastoma.     

Anomalous conformational change in 1-butyl-3-methylimidazolium tetrafluoroborate-D2O mixtures

We have investigated the effect of deuterated water on the conformational equilibrium between the gauche and trans conformers of the [bmim] cation in mixtures of water and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]), an ionic liquid, at room temperature. A comparison of the results obtained from solutions made with H(2)O and with D(2)O highlights an anomalous conformational change in the D(2)O solution showing an extended N-shaped behavior. The gauche conformer of the [bmim] cation in D(2)O increased up to x = ~50 (D(2)O mol %); however, it decreased up to higher water concentrations of x = ~85 before again increasing drastically toward x = ~100. We provide spectroscopic evidence that the anomalous conformational dynamics of the [bmim] cation in D(2)O is directly related to the H/D exchange reaction of the C-H group at position 2 of the imidazolium ring.     

Effect of Cocatalyst in Ethylene/Styrene Copolymerization by Aryloxo‐Modified Half‐Titanocene–Cocatalyst Systems for Exclusive Synthesis of Copolymers at High Styrene Concentrations

Factors affecting the product distributions in ethylene/styrene copolymerizations catalyzed by Cp*TiCl₂(O‐2,6‐ⁱPr₂C₆H₃) are explored in the presence of various cocatalysts at high styrene/ethylene feed ratios (at 40 and 55 °C). Ethylene/styrene copolymers were the sole product when the reactions were conducted in the presence of [PhN(H)Me₂][B(C₆F₅)₄] and AlⁱBu₃/Al(octyl)₃ even at 55 and 70 °C, whereas syndiotactic polystyrene was by‐produced when the polymerizations were performed at >40 °C in the presence of MAO; the ratios of the copolymer/SPS were affected by the reaction temperature as well as Al cocatalyst employed.