Analytical use of a biochemical luminous membrane

Luminous membranes were prepared by immobilizing peroxidase (POD) to collagen matrix. The POD luminous membrane generated luninescence in the presence of luminol and H₂O₂, and the peroxide was determined in the concentration range 10-⁶-10-³ M by following luminescence emitted from the membrane. Glucose was determined using a luminous membrane in which POD and glucose oxidase (GOD) were coimmobilized. The luminous membranes appear to be feasible for the determination of enzyme substrates and enzyme activity.     

Search for a simpler synthetic model system for intramolecular 1,3-dipolar cycloaddition to the 5,6-double bond of a pyrimidine nucleoside

In search for a simpler model system for the study of intramolecular thermal reactions between the base and 5'-functionalized sugar moiety in nucleosides, 1-(3-azidopropyl)uracil (2), 1-(4-azidobutyl) pyrimidines (12 and 13) and 1-(5-azidopentyl)-uracil (14) was synthesized through the corresponding ω-benzoyloxy-(6,7 and 8) and ω-hydroxyalkyl-pyrimidines (9,10 and 11). Heating 2 gave 1,N⁶-trimethylene-6-aminouracil (4), while heating 12 and 13 gave N¹-C₆ cleaved addition products. 15 and 16, respectively. 15 was regiospecifically transformed to 1,2,3-triazole derivatives, 17,18 and 19. Heating 1-(4-azidobutyl)-5-bromouracil (20) yielded 3,9-tetramethylene-8-azaxanthine (22). 9 with NBA gave 1,0⁶-tetramethylene-5-bromo-6-hydroxy-5,6-dihydrouracil (24) and the 5-brominated analog of 9 (25). The 4-functionalized butyl side chain proved to serve as a substitute for the 5'-functionalized sugar moiety in pyrimidine ribonucleosides.     

Syntheses and structures of mono-, di- and tetranuclear rhodium or iridium complexes of thiacalix[4]arene derivatives

The reactions of [Cp*MCl2]2(Cp*=eta5-C5Me5, M = Rh, Ir) with thiacalix[4]arene (TC4A(OH)4) and tetramercaptothiacalix[4]arene (TC4A(SH)4) gave the mononuclear complexes [(Cp*M){eta3-TC4A(OH)2(O)2}] and the dinuclear complexes [(Cp*M)2{eta3eta3-TC4A(S)4}] respectively, while the analogous reactions with dimercaptothiacalix[4]arene (TC4A(OH)2(SH)2) produced the tetranuclear complexes [(Cp*M)2(Cp*MCl2)2-{eta3eta3eta1eta1-TC4A(O)2(S)2}].     

A new-type photoreaction of a carbonyl compound: Part 2. Photoinduced ω-bond dissociation in p-halomethylbenzophenone studied by time-resolved EPR technique and laser flash photolysis

Photodissociation of the carbon-X (X = Br and Cl) bonds in p-bromo- and p-chloromethylbenzophenone (BMBP and CMBP) in solution were investigated by time-resolved EPR and laser flash photolysis techniques. BMBP and CMBP were found to undergo ω-bond cleavage to yield the p-benzoylbenzyl radical (BBR) at 295 K, and the quantum yields (Φ_BBR) were determined. The CIDEP signal originated from BBR formed upon decomposition of CMBP was obtained while that for BMBP was absent. By using triplet sensitization of acetone, the efficiencies (_BBR) of the CX bond fission in the triplet states of BMBP and CMBP were determined. The agreement between the Φ_BBR and _BBR values for CMBP indicates that the CCl bond dissociation occurs only in the triplet state. In contrast to CMBP, the cleavage of the CBr bond in BMBP upon direct excitation was concluded to be the event only in the excited singlet state without triplet formation, whereas the triplet state was also reactive for ω-bond dissociation. The rate of CBr bond dissociation seemed to be greater than that of intersystem crossing from the S₁ to the T₁ state. Schematic energy diagrams of the excited states of BMBP and CMBP were shown, and the reaction profiles were discussed from the viewpoint of the CX bond enthalpies.     

Janus particles with a functional gold surface for control of surface plasmon resonance

We report in this study the presence of Janus particles, which are candidates for use with electronic color papers. We used negatively charged polystyrene particles (370 nm) as the core particles, and gold was then sputtered onto their packed monolayer under several conditions. The sputtered particles were next redispersed into the aqueous medium by gentle sonication. Gold nanoparticles localized on one side of the cores could also serve as seeds for subsequent shell growth by electroless gold plating. Through these treatments, a series of well-dispersed Janus particles were obtained with gold nanostructures of different size and shape only on one side. Their dispersions showed different colors originating from the surface plasmon resonance absorption of gold nanoparticles localized on the hemisphere. The particles obtained by this approach have potential applications such as in sensors and electronic color paper.     

Novel syntheses of enantiopure hexahydroimidazo[1,5-b]isoquinolines and tetrahydroimidazo[1,5-b]isoquinolin-1(5H)-ones via iminium cation cyclizations

Condensations of chiral diamines 11a-c with benzotriazole and formaldehyde gave benzotriazolyl intermediates 12a-c; similar condensations of alpha-amino-amides 10a-c with benzotriazole and paraformaldehyde gave 14a-c. Subsequent treatment of 12a-c and 14a-c with AlCl(3) led to enantiopure tricyclic 1,2,3,5,10,10a-hexahydroimidazo[1,5-b]isoquinolines 1a-c and 2,3,10,10a-tetrahydroimidazo[1,5-b]isoquinolin-1(5H)-ones 15a-c, respectively, via Lewis acid promoted iminium cation cyclizations.     

Release from or through a wax matrix system. IV. Generalized expression of the release process for a reservoir device tablet

Generalization of the release process through the wax matrix layer was examined by use of a reservoir device tablet. The wax matrix layer of the reservoir device tablet was prepared from a physical mixture of lactose and hydrogenated castor oil to simplify the release properties. Release through the wax matrix layer showed zero-order kinetics in a steady state after a given lag time, and could be divided into two stages. The first stage was the formation process of water channel by dissolving the soluble component in the wax matrix layer. The lag time obtained by applying the square root law equation was well connected with the amount of the matrix layer and mixed weight ratio of components in this layer. The second stage was the zero-order release process of drug in the reservoir through the wax matrix layer, because the effective surface area was fixed. The release rate constants were connected with thickness of the matrix layer and permeability coefficient, and the permeability coefficients were connected with the diffusion coefficient of drug and porosity. Hence the release rate constant could be connected with the amount of matrix layer and the mixed weight ratio of components in the matrix layer. It was therefore suggested that the release process could be generalized using the amount of matrix layer and the mixed weight ratio of components in the matrix layer.     

Synthetic approach to natural products by Claisen rearrangement of glyceraldehyde derivatives

For the purpose of organic syntheses of some corynanthe-type indole alkaloids, sesquiterpenes, and steroids, optically active intermediates cyclopentanone 3-allylalcohol, α-methylene-γ-butylo lactones andtrans-hydrindanone-propionic acid, were synthesized from (R)- and (S)-isopropylideneglyceraldehyde derived fromD-mannitol andLascorbic acid, respectively, utilizing Claisen rearrangement as a key reaction. Actually total syntheses of natural alkaloids, (-)-antirhine, (+)-dihydroantirhine and (-) dihydrocorynantheol were accomplished.     

Bitterness evaluation of medicines for pediatric use by a taste sensor

The purpose of this study was to evaluate the bitterness of 18 different antibiotic and antiviral drug formulations, widely used to treat infectious diseases in children and infants, in human gustatory sensation tests and using an artificial taste sensor. Seven of the formulations were found to have a bitterness intensity exceeding 1.0 in gustatory sensation tests (evaluated against quinine as a standard) and were therefore assumed to have an unpleasant taste to children. The bitterness intensity scores of the medicines were examined using suspensions in water or an acidic sports drink. In the case of three macrolide antibiotic formulations containing erythromycin (ERYTHROCIN dry syrup), clarithromycin (CLARITH dry syrup for pediatric), and azithromycin (ZITHROMAC fine granules for pediatric use), the bitterness intensities of suspensions in acidic sports drinks were dramatically enhanced compared with the corresponding scores of suspensions in water. This enhancement could be predicted using the taste sensor. On the other hand, a reduction of bitterness intensity was observed for an acidic sports drink suspension of an amantadine product (SYMMETREL fine granules) compared with an aqueous suspension. This reduction in bitterness could also be predicted using the taste sensor output value. Thus, the taste sensor could predict whether or not suspension in an acidic sports drink would enhance or reduce the bitterness intensity of pediatric drug formulations, compared with suspensions in water.