Simultaneous determination of neptunium,plutonium, americium and curium using coprecipitation with bismuth phosphate

Radiochemical studies of the coprecipitation behaviour of neptunium, plutonium, americium and curium with bismuth phosphate were carried out on the basis of the effect of the following variables: kinds of acid, acidity, and amounts of bismuth and coexisting other elements. Simultaneous determination of the actinide elements using the coprecipitation was accomplished by adding 1 mg of bismuth at 0.2M phosphoric acid and by direct measurement of alpha spectrum of the precipitates. The order of the coprecipitation yields of the elements was also discussed by the difference of both the oxidation states and sulfate complex formation.     

Synthesis of optically active methyl 7 beta-hydroxykaurenoate with potent neuroprotective activity

(-)-Methyl 7 beta-hydroxykaurenoate (3) and its 4-demethyl acetate (-)-4 were both synthesized via methods that contained radical cyclization and intramolecular Diels-Alder reactions as key steps. Both compounds displayed potent neuroprotective activity against N-methyl-D-aspartate toxicity in cultured cortical neurons.     

Acridine derivatives. VI . Redox chemistry of novel 9-anilinoacridines with antitumor activities

In order to elucidate the mechanism of deoxyribonucleic acid (DNA) strand breaks caused by 9-anilino-acridine DNA intercalators, the antitumor activity of L1210, P388 and the reduction-oxidation (redox) reaction of 9-anilinoacridines were studied. The redox reaction induced by two electrons causing structural changes in quinone diimines of 9-anilinoacridines is believed to be an important factor in DNA strand breaks and was examined by means of temperature-dependent nuclear magnetic resonance and cyclic voltammetry. The redox reaction of 9-anilinoacridines is induced by the effect of a low-energy electron transfer from the acridine to the aniline ring. We propose that the redox reaction plays an important role in the DNA strand cleavage of 9-anilinoacridine when it is intercalated into double-strand DNA.     

Flow injection of lithium ion using chromogenic 14-crown-4 derivatives as extraction-spectrophotometric reagents

A system for flow injection of Li+ has been designed, with use of proton-dissociable chromogenic 14-crown-4 derivatives as the extraction-spectrophotometric reagents, and the analytical conditions have been optimised. This flow injection system showed high selectivity for Li+ reflecting the cation-complexing property of the chromogenic crown ethers. The determination of Li+ in the clinical range in blood under a high Na+ background of 130-160 mM was feasible, with a small sample size (50 microliters) and high sampling rate (more than 100 injections per hour), with this method. The proposed extraction-spectrophotometric flow injection system was, therefore, found to be promising for the efficient determination of Li+ in biological samples, such as blood sera, with a high Na+ background.     

Development of a molecular recognition ion gating membrane and estimation of its pore size control

We have fabricated a molecular recognition ion gating membrane. This synthetic membrane spontaneously opens and closes its pores in response to specific solvated ions. In addition to this switching function, we found that this membrane could control its pore size in response to a known concentration of a specific ion. The membrane was prepared by plasma graft copolymerization, which filled the pores of porous polyethylene film with a copolymer of NIPAM (N-isopropylacrylamide) and BCAm (benzo[18]crown-6-acrylamide). NIPAM is well-known to have an LCST (lower critical solution temperature), at which its volume changes dramatically in water. The crown receptor of the BCAm traps a specific ion, and causes a shift in the LCST. Therefore, selectively responding to either K(+) or Ba(2+), the grafted copolymer swelled and shrank in the pores at a constant temperature between two LCSTs. The solution flux in the absence of Ba(2+) decreased by about 2 orders of magnitude over a solution flux containing Ba(2+). The pore size was estimated by the filtration of aqueous dextran solutions with various solute sizes. This revealed that the membrane changed its pore size between 5 and 27 nm in response to the Ba(2+) concentration changes. No such change was observed for Ca(2+) solutions. Furthermore, this pore size change occurred uniformly in all pores, as a clear cut-off value for a solute size that could pass through pores was always present. This membrane may be useful not only as a molecular recognition ion gate, but also as a device for spontaneously controlling the permeation flux and solute size.     

Central depressant effects of N3-substituted 6-azauridines in mice.

Central depressant effects in mice of N3-substituted 6-azauridines (6-AzUd) (1) were examined by intracerebroventricular (i.c.v.) injection. Eleven derivatives including alkyl-, benzyl-, xylyl- and phenylethyl-substitution onto the N3-position of 1 were synthesized and their pharmacological effects were evaluated using hypnotic activity, locomotor activity, motor incoordination and pentobarbital-induced sleep prolongation as indices. Six of 12 compounds showed the hypnotic activity. At a dose of 2 mumol/mouse, the mean sleeping time induced by 1, N3-benzyl-6-AzUd (7), N3-o-xylyl-6-AzUd (8), N3-m-xylyl-6-AzUd (9), N3-p-xylyl-6-AzUd (10) and N3-alpha-phenylethyl-6-AzUd (11) was 14, 11, 45, 12, 9 and 16 min, respectively. These derivatives and N3-beta-phenylethyl-6-AzUd (12) (1.5 mumol/mouse) significantly prolonged pentobarbital-induced (40 mg/kg, i.p.) sleeping time, whereas none of the N3-alkylated derivatives (methyl-, ethyl-, n-propyl-, n-butyl- and allyl-substitution) exerted the hypnotic activity or pentobarbital-induced sleep prolongation. Nucleoside 1 and its xylyl-derivatives (1.5 mumol/mouse) significantly decreased locomotor activity of mice, their effects paralleled the hypnotic activity. These compounds (1.5 mumol/mouse) also produced motor incoordination and potentiated the effect of diazepam-induced motor incoordination. These results indicate that 1 and its benzyl-related derivatives, but not alkyl-derivatives have a depressant effect on the central nervous system.     

Selective reduction of NOX with C3H6 over Cu incorporated into silicoalumino-phosphate (SAPO)

Cu ion-exchanged SAPO-34 which is a highly active catalyst for selective reduction of NO with C₃H₆, was synthesized and the Cu ion was characterized in the SAPO-34 by ESR, XPS, IR, and XAFS. ESR study indicated that two kinds of Cu(II) with different environments exist in SAPO-34. The Cu(II) species disappeared immediately by C₃H₆ treatment and recovered by oxygen treatment. XAFS study indicated that most of the Cu(II) was reduced to Cu(I) under the presence of C₃H₆. These studies revealed that a selective NO reduction by C₃H₆ over SAPO-34 should proceed by the redox reaction of a copper ion between Cu(I) and Cu(II).     

Synthesis and Complexing Ability of Azacrownophanes: The Cyclodextrin Catalysis of the Photochemical Cyclization Reaction

Azacrownophanes were efficiently prepared by the irradiation of precursor ammonium chlorides in the presence of -CD (-cyclodextrin) in aqueous solution, by repressing the amino group-quenching effect by inclusion of the styrene moieties in -CD. In liquid–liquid extraction, azacrownophanes (6 and 7) showed affinity toward both Ag⁺ and Pb²⁺ cations in a series of heavy metal nitrates. Both 6 and 7 formed 1:1 complexes with the above two cations, according to ¹³C NMR titration and ESI-MS analysis.     

Sensitive and simultaneous determination of HIV protease inhibitors in rat biological samples by liquid chromatography-mass spectrometry

A sensitive and simultaneous liquid chromatographic-mass spectrometric (LC/MS) method for the determination of current four HIV protease inhibitors (PIs), indinavir (IDV), saquinavir (SQV), nelfinavir (NFV) and amprenavir (APV) in rat plasma and liver dialysate by a microdialysis method was described. An isocratic LC/MS method in combination with atmospheric pressure chemical ionization was developed for the determination of these four PIs in biological samples in the same run. The analytes including an internal standard were extracted from 100 microL of plasma or 150 microL of liver dialysate samples by salting-out with 100 microL of ice-cold 2 M K(3)PO(4) followed by ether extraction. The separation of analytes was carried out on a reversed-phase semi-micro column using 50% of acetonitrile containing 1% acetic acid as mobile phase at a flow rate of 0.2mL/min(-1). The separation was completed within 5 min. Precision, recovery and limits of detection indicated that the method was suitable for the quantitative determination of these PIs in rat plasma or liver dialysate. This simple, sensitive and highly specific LC/MS method is suitable for pharmacokinetic studies and therapeutic drug monitoring in AIDS patients who receive double protease therapy.     

Unique hydrogenation activity of supported tin catalyst: Selective hydrogenation catalyst for unsaturated aldehydes

Selective hydrogenation of unsaturated aldehydes, crotonaldehyde (CH₃CH=CHCH=O) and cinnamaldehyde (C₆H₅CH=CHCH=O), has been studied over SiO₂-supported monometallic Sn and bimetallic Rh---Sn catalysts in the liquid phase. Over a silica-supported monometallic Rh catalyst, Rh/SiO₂, no unsaturated alcohol (crotyl alcohol or cinnamyl alcohol) was formed, whereas considerable amounts of the corresponding saturated aldehyde and saturated alcohol were obtained. The selectivity to the unsaturated alcohol was improved over the Rh---Sn bimetallic catalyst. The selectivity to the corresponding unsaturated alcohol attained ca. 65% over the Rh---Sn bimetallic catalysts. On the other hand, The supported Sn catalyst showed markedly high selectivity to the unsaturated alcohols. The selectivity of the Sn/SiO₂, attained 95% to crotyl alcohol and 100% to cinnamyl alcohol, respectively. Although the conversion of each unsaturated aldehyde over Rh---Sn/SiO₂ catalysts was greater than that over Sn/SiO₂ catalysts, the selectivity of Sn/SiO₂ catalysts to the corresponding unsaturated alcohols was superior to that over Rh---Sn/SiO₂. The selectivity of Sn/SiO₂ was also compared with that of Rh---Sn/SiO₂ at a similar conversion of the unsaturated aldehydes. The selectivity of Sn/SiO₂ was significantly greater than that of the Rh---Sn bimetallic catalyst. These results indicate that the high selectivity over Sn/SiO₂ was ascribed not to low conversion but to intrinsic selectivity of the Sn catalyst.