The synthesis of novel polycyclic heterocyclic ring systems. 2. Naphmo[2,1-b:4,3-g]bisbenzo[b]thiophene

The novel polycyclic heterocyclic ring system, naphtho[2,1-b:4,3-g]bisbenzo[b]thiophene was synthesized from 5-[2-(2-bromo-3-thienyl)ethenyl]naphtho[2,1-b][1]benzothiophene. The assignment of its ¹H and ¹³C nmr spectra was also accomplished by utilizing two-dimensional nmr methods.     

Redispersible dry emulsion system as novel oral dosage form of oily drugs: in vivo studies in beagle dogs.

The absorption characteristics of vitamin E acetate (VEA) formulated into a dry emulsion system after its oral administration to beagle dogs were determined and compared to those of two different dosage forms (an oily mixture of the drug with cottonseed oil and an oil (drug)-in-water emulsion). The three dosage forms were administered in a crossover fashion to six nonfasting subjects, and the drug absorption was assessed from the plasma concentration of the major metabolite (free vitamin E). VEA formulated in the dry emulsion was rapidly absorbed, which suggested that a considerable amount was released as reformed emulsion droplets in the gastrointestinal tract as well as in water in vitro. Based on the analysis of variance, no significant differences in bioavailability parameters (AUC, Cmax or Tmax) were observed among the three dosage forms.     

Catalytic enantioselective conjugate addition of cyanide to alpha,beta-unsaturated N-acylpyrroles

A catalytic enantioselective conjugate addition of cyanide to alpha,beta-unsaturated N-acylpyrroles was developed using the chiral gadolinium catalyst generated from Gd(OiPr)3 and d-glucose-derived ligand 2. Generally high enantioselectivity was obtained from a wide range of substrates; substrates with beta-aryl and beta-vinyl substituents and alpha,beta-disubstituted substrates can now be used. Using this reaction as a key step, short-step syntheses of several pharmaceuticals and their lead compounds were achieved, including the beta-phenyl-substituted GABA analogue and pregabalin.     

Carrier doping effect into quasi-one-dimensional bromo-bridged Ni(III) complexes with strong electron-correlation by Cu(II) ions, [Ni1-xCux(chxn)2Br]Br2-x

This communication will describe the electron doping effect into Ni(III) complexes by Cu(II) ions, [Ni(1-x)Cu(x)(chxn)(2)Br]Br(2-x) (x = 0.038 and 0.101) by using an electrochemical oxidation method. A drastic increase of electrical conductivity as well as a new absorption band around 0.5 eV in single crystal reflectance spectra was observed by doping Cu(II) ions, indicating the electron doping was successfully made. An ESR result shows unpaired electrons locate in the d(x2-y2) orbitals of Cu(II) and have almost no interaction with those of other ions.     

Polycyclic N-hetero compounds. XXXVIII. Synthesis and evaluation of antidepressive activity of [1]benzothieno[2′,3′:4,5]furo[3,2-d]primidines and their precursors

Synthesis of [1]benzothieno[2′,3′:4,5]furo[3,2-d]pyrimidines is described. Antidepressive evaluation of these compounds and their precursors were screened by inhibitory action of reserpine-induced hypothermia.     

High-performance liquid chromatographic determination of pamaquine, primaquine and carboxy primaquine in calf plasma using electrochemical detection.

A high-performance liquid chromatographic method with electrochemical detection is described for quantification of pamaquine, primaquine and carboxy primaquine in calf plasma. After the proteins had been precipitated with acetonitrile, the drugs were separated on a 5-microns C18-modified polymer gel column with an isocratic mobile phase. The detection limit was 0.01 microgram/ml in plasma for all three compounds. The applicability of the method in pharmacokinetic studies was demonstrated by determining the plasma concentrations of the three substances in calves administered a single dose of pamaquine or primaquine.     

Polycyclic N-heterocyclic compounds. 48. syntheses of furo[2,3-h]-[1,6]naphthyridine and imidazo(or pyrimido)[2,1-f]-[1,6]naphthyridines with rearrangement

The formation of a novel ring system, furo[2,3-h][1,6]naphthyridine via the Smiles rearrangement and intramolecular cyclization is described. Cyclization of 5-(ω-hydroxyalkylamino)-8-methyl-1,2-dihydrofuro[2,3-h][1,6]naphthyridines provided novel spiro compound with rearrangement.     

Platinum submonolayer-monolayer electrocatalysis: An electrochemical and X-ray absorption spectroscopy study

A new Pt monolayer electrocatalyst concept is described and the results of electrochemical and X-ray absorption spectroscopy (XAS) studies are presented. Two new methods that facilitate the application of this concept in obtaining ultra-low-Pt-content electrocatalysts have been developed. One is the electroless (spontaneous) deposition of a Pt submonolayer on Ru nanoparticles, and the other is a deposition of a Pt monolayer on Pd nanoparticles by redox displacement of a Cu adlayer. The Pt submonolayer on Ru (PtRu₂₀) electrocatalyst demonstrated higher CO tolerance than commercial catalysts under conditions of rotating disk experiments. The long-term stability test showed no loss in performance over 870 h using a fuel cell operating under real conditions, even though the Pt loading was approximately 10% of that of the standard Pt loading. In situ XAS indicated an increase in d-band vacancy of deposited Pt, which may facilitate partly the reduced susceptibility to CO poisoning for this catalyst. The kinetics of O₂ reduction on a Pt monolayer on Pd nanoparticles showed a small enhancement in comparison with that from a Pt nanoparticle electrocatalyst. The increase in catalytic activity is partly attributed to decreased formation of PtOH, as shown by XAS experiments.     

Locked TASC probes for homogeneous sensing of nucleic acids and imaging of fixed E. coli cells

We have designed a second-generation TASC (target-assisted self-cleavage) probe. It is based on the switching-on of incorporated cis-acting DNAzyme activity upon the target-induced conformational change of the otherwise inactive off-target probes locked in an intrastrand base-paired hairpin geometry. With E. coli 16S ribosomal RNA-relevant oligonucleotides as targets, the locked TASC probe exhibits an allosteric factor of k(on)/k(off) = 65 and the sequence selectivity is high, in terms of single nucleotide difference, when particular sequence and length of targets are chosen. Preliminary experiments with fixed E. coli cells show that the locked TASC probe with a FRET pair can be used to image fixed E. coli cells.