Determination of memantine in rat plasma by HPLC-fluorescence method and its application to study of the pharmacokinetic interaction between memantine and methazolamide

A sensitive high-performance liquid chromatographic method with fluorescence detection was developed to determine memantine (MT) in rat plasma. The method consists of pre-column labeling of MT with 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) and a clean-up step with solid-phase extraction. A good separation of DIB-MT was achieved within 12 min on an octadecylsilica (ODS) column (150 × 4.6 mm i.d.; 5 μm) with a mobile phase of acetonitrile-water (70:30, v/v). The calibration curve prepared with fluoxetine as an internal standard showed good linearity in the range of 10-400 ng/mL (r = .999). The limits of detection and quantitation at signal-to-noise ratios of 3 and 10 were 2.0 and 6.6 ng/mL, respectively. The method was shown to be reliable with precisions of <5% for intra-day and <9% for inter-day as relative standard deviation. The fluorescence property and reaction yield of authentic DIB-MT were also examined. The proposed method was successfully applied to study the pharmacokinetic interaction between MT and methazolamide.     

Simultaneous determination of N-benzylpiperazine and 1-(3-trifluoromethylphenyl)piperazine in rat plasma by HPLC-fluorescence detection and its application to monitoring of these drugs

An HPLC‐fluorescence detection method for simultaneous determination of N‐benzylpiperazine (BZP) and 1‐(3‐trifluoromethylphenyl)piperazine (TFMPP) labeled with 4‐(4,5‐diphenyl‐1 H‐imidazol‐2‐yl)benzoyl chloride (DIB‐Cl) was described. DIB‐BZP and ‐TFMPP were well separated within 13 min without interference of peaks from plasma components. The lower detection limits of BZP and TFMPP at a signal‐to‐noise ratio of 3 were 0.9 and 4.6 ng/mL, respectively. Precisions of the proposed method for intra‐ and inter‐day assays were less than 4.8 and 9.1% as %RSD (n = 5). Furthermore, the method could be successfully applied to monitor both compounds in plasma after their sole or co‐administration to rats (each dose, 2 mg/kg). Clearance of TFMPP was significantly different under the conditions (P = 0.047). Copyright © 2011 John Wiley & Sons, Ltd.     

Diastereoselective synthesis of 3,3-disubstituted oxindoles from atropisomeric N-aryl oxindole derivatives

Diastereoselective synthesis of 3,3-disubstituted oxindoles has been examined by transformations involving nucleophilic addition, alkylation, and cycloaddition using chiral racemic N-aryl oxindoles bearing C–N axial chirality. The most striking features of this approach are high diastereoselectivities (up to >95:<5) when using ortho-monosubstituted N-aryl oxindoles and easy removal of the p-(benzyloxy)aryl moiety in the axially twisted amides by a mild two-step sequence.     

Stereocontrolled synthesis of substituted chiral piperidines via one-pot asymmetric 6π-azaelectrocyclization: asymmetric syntheses of (-)-dendroprimine, (+)-7-epidendroprimine, (+)-5-epidendroprimine, and (+)-5,7-epidendroprimine

The asymmetric one-pot 6π-azaelectrocyclization of alkenyl vinyl stannane, ethyl (Z)-2-iodo-4-oxobutenoate, and (-)-7-isopropyl-cis-aminoindanol in the presence of a Pd(0) catalyst stereoselectively produced the tetracyclic aminoacetal compounds, resulting from the four-bond formation accompanying by controlling the stereochemistry at the two asymmetric centers. The produced cyclic aminoacetals can be regarded as synthetic precursors of substituted chiral piperidines, and the syntheses of 2,4- and 2,4,6-substituted piperidines were realized from the obtained aminoacetals by the stereoselective hydrogenation of the double bond conjugated with the C-4 ester group and alkylation at the aminoacetal moiety. In addition, the stereoselective synthesis of an indolizidine alkaloid, (-)-dendroprimine, and its three stereoisomers, (+)-7-epidendroprimine, (+)-5-epidendroprimine, and (+)-5,7-epidendroprimine, were achieved.     

Search of Kaonic Nuclear States at the SuperB factory

The search of nuclear bound states of ${\bar{K}}$ in few-body nuclear systems such as K ^? pp, can be extended from the nuclear medium to the vacuum, using the glue-rich ${\Upsilon(1S)}$ decays at B-factories. Here the possibility for such a measurement at the future SuperB factory is discussed.     

Low‐temperature and high-pressure apparatus developed at ISSP,University of Tokyo

A high-pressure apparatus with cubic-anvil device has been successfully working for more than 10 years at low temperatures down to 2?K under quasi-hydrostatic pressure up to 10?GPa in study of solid-state physics. Main parts of it are composed of a set of compact cubic-anvils, a top-loading high-pressure cryostat and a 250?ton press. All the particulars of the cubic-anvil apparatus are given, including pressure calibrations at low temperature.     

Pressure effect on the magnetic phase diagram of Hf1-xTaxFe2 alloys

Abstract

The lattice constants of Hf_1-xTa_xFe₂ with C14 structure were measured at room temperature under pressure up to 5 GPa. The magnetic phase diagram obtained as a function of pressure was compared with that obtained as a function of Ta concentration x. It is shown that changes in lattice constants by applying pressure and /or by substituting Ta for Hf affect remarkably the magnetic phase stability, which is consistent qualitatively with a recent theoretical prediction based on the local spin density approximation.     

X-ray diffraction studies on oxide-superconductors under pressure by a new X-ray detection system

Abstract

A new high pressure x-ray diffraction system has been developed, which consists of a diamond anvil cell, an imaging plate as a detector and an 18 kW rotating anode type generator. By this system we found an anisotropic compression and anomalies in linear compressibility for the Bi-oxide superconductors.