The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform
Hiromi Yamashita - One of the best experts on this subject based on the ideXlab platform.
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pdag nanoparticles supported on functionalized mesoporous carbon promotional effect of surface amine groups in reversible hydrogen delivery storage mediated by formic acid co2
ACS Catalysis, 2018Co-Authors: Shinya Masuda, Kohsuke Mori, Yuya Futamura, Hiromi YamashitaAbstract:Highly dispersed PdAg nanoparticles supported on phenylamine-functionalized mesoporous carbon were synthesized and assessed as bifunctional heterogeneous catalysts for the interconversion of formic acid (FA) and CO2 in chemical hydrogen storage systems. A high turnover frequency (TOF) of 5638 h–1 for evolved H2 on the basis of the total amount of Pd in the sample was obtained during the dehydrogenation of FA, corresponding to a TOF value of 21686 h–1 on the basis of the quantity of surface Pd atoms. In addition, this material promoted the hydrogenation of CO2 to FA with a turnover number (TON) of 839 over 24 h for produced FA on the basis of the total amount of Pd, corresponding to a TON of 3227 on the basis of the quantity of surface Pd atoms. Both the synergistic alloying effect and the surface functionalization with weakly basic phenylamine molecules were vital aspects of these high catalytic activities. Experimental and theoretical studies revealed that the cooperative action of the phenylamine groups...
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phenylamine functionalized mesoporous silica supported pdag nanoparticles a dual heterogeneous catalyst for formic acid co2 mediated chemical hydrogen delivery storage
Chemical Communications, 2017Co-Authors: Shinya Masuda, Kohsuke Mori, Hiromi Yamashita, Hiromasa Tanaka, Kazunari Yoshizawa, Michel CheAbstract:A PdAg-based nanoparticle catalyst supported on the mesoporous silica material, SBA-15, modified with a weakly basic phenylamine functional group has been developed as a dual heterogeneous catalyst for the H2 delivery and H2 storage reactions mediated by formic acid and carbon dioxide.
Kohsuke Mori - One of the best experts on this subject based on the ideXlab platform.
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pdag nanoparticles supported on functionalized mesoporous carbon promotional effect of surface amine groups in reversible hydrogen delivery storage mediated by formic acid co2
ACS Catalysis, 2018Co-Authors: Shinya Masuda, Kohsuke Mori, Yuya Futamura, Hiromi YamashitaAbstract:Highly dispersed PdAg nanoparticles supported on phenylamine-functionalized mesoporous carbon were synthesized and assessed as bifunctional heterogeneous catalysts for the interconversion of formic acid (FA) and CO2 in chemical hydrogen storage systems. A high turnover frequency (TOF) of 5638 h–1 for evolved H2 on the basis of the total amount of Pd in the sample was obtained during the dehydrogenation of FA, corresponding to a TOF value of 21686 h–1 on the basis of the quantity of surface Pd atoms. In addition, this material promoted the hydrogenation of CO2 to FA with a turnover number (TON) of 839 over 24 h for produced FA on the basis of the total amount of Pd, corresponding to a TON of 3227 on the basis of the quantity of surface Pd atoms. Both the synergistic alloying effect and the surface functionalization with weakly basic phenylamine molecules were vital aspects of these high catalytic activities. Experimental and theoretical studies revealed that the cooperative action of the phenylamine groups...
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phenylamine functionalized mesoporous silica supported pdag nanoparticles a dual heterogeneous catalyst for formic acid co2 mediated chemical hydrogen delivery storage
Chemical Communications, 2017Co-Authors: Shinya Masuda, Kohsuke Mori, Hiromi Yamashita, Hiromasa Tanaka, Kazunari Yoshizawa, Michel CheAbstract:A PdAg-based nanoparticle catalyst supported on the mesoporous silica material, SBA-15, modified with a weakly basic phenylamine functional group has been developed as a dual heterogeneous catalyst for the H2 delivery and H2 storage reactions mediated by formic acid and carbon dioxide.
Hendrik Timmerman - One of the best experts on this subject based on the ideXlab platform.
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Prenylamine derivatives as blockers of the vesicular transporter for dopamine. A quantitative structure-activity study
European Journal of Medicinal Chemistry, 1997Co-Authors: A Vaccari, Pl Saba, Mp Caldirola, Greetje J. Bijloo, Hendrik TimmermanAbstract:Summary A new series of diphenylalkylamine congeners of Prenylamine have been assayed in binding experiments on rat striatal membrane preparations. The aim was to ascertain the influence of structural modifications and lipophilicity on their interaction with the [ 3 H]tyramine-labeled vesicular transporter for dopamine. Thirteen compounds potently inhibited the specific binding of [ 3 H]tyramine, with nanomolar K i , values in the range of those of established markers for the vesicular transporter of dopamine. Less lipophilic compounds displayed higher affinity for the energy-dependent amine transporter.
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New Prenylamine-analogues: investigations of their influence on calcium-dependent biological systems
European Journal of Medicinal Chemistry, 1993Co-Authors: P Caldirola, P. Zandberg, Raimund Mannhold, Hendrik TimmermanAbstract:Abstract Chemically, Prenylamine belongs to the diphenylalkylamine class. Compounds of this class are calcium antagonists with a broad spectrum of activities due to their influence on both extracellular and intracellular sites. In the present study the calcium antagonistic profile of a recently developed new series of Prenylamine analogues has been investigated using different in vitro systems. The inhibiting concentrations for the most active compound are ≈ 1.5 μM; several derivatives are inactive up to a concentration of 10 μM. Structural modifications towards an increase of lipophilicity make these molecules interact (inhibition) with the intracellular calcium-binding protein calmodulin; for the series no correlation between calcium-blocking and calmodulin antagonistic effects has been found.
R. Pernice - One of the best experts on this subject based on the ideXlab platform.
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Basic mechanisms underlying Prenylamine-induced ‘torsade de pointes’: differences between Prenylamine and fendiline due to basic actions of the isomers
Current Medical Research and Opinion, 2008Co-Authors: R. Bayer, J. Schwarzmaier, R. PerniceAbstract:The calcium antagonists Prenylamine and fendiline both bind with rather low affinity to the dihydropyridine (nifedipine) binding site. As calmodulin (CaM) antagonists, they both inhibit CaM-dependent enzymes and relax smooth muscle preparation in nearly the same concentration range. If compared with other calcium antagonists, their action on smooth muscle develops rather slowly and cannot be inhibited by the calcium agonist Bay k 8644. In contrast, basic pharmacology reveals major differences of the actions of Prenylamine and fendiline in heart muscle, indicating that, after all, the change in structure close to the asymmetric carbon strongly influences the molecular action of the compounds and their respective isomers. The negative inotropic effect of racemic Prenylamine is rather independent of stimulation rate, whereas fendiline preferably depresses contraction at high rate stimulation. The negative inotropic potencies are determined by the (-)-isomers, but only in the case of Prenylamine the isomeric ratio of 6 reveals a considerable stereoselectivity of action. In low concentrations and preferably at low rate stimulation, (+)-Prenylamine exerts a strong positive inotropic effect. At low rate stimulation, total duration of transmembrane action potential is prolonged by (+/-)- and (+)-Prenylamine, but discretely shortened by (+/-)- and (+)-fendiline. At high rate stimulation, it is shortened by (+/-)- and (-)-Prenylamine, but prolonged (only) at the very final repolarization level by (+/-)- and (-)-fendiline. The positive inotropic action of Prenylamine and the prolongation of action potential at low stimulation rate can be interpreted as a calcium agonistic side-effect due to the action of the (+)-isomer. It seems possible that, under the condition of low heart rate, Prenylamine (as reported for the calcium agonist Bay k 8644) increases the potential-dependent transmembrane calcium current. In addition, it is argued that during the long-lasting action potential, a reactivation of the calcium current induces early after-depolarizations. These effects are postulated to represent the main mechanisms triggering torsade de pointes during therapy with Prenylamine. Though fendiline, from a chemical point of view, rather resembles Prenylamine, its pharmacological profile is different. In particular, in regard to electrophysiology, torsade de pointes are not expected to be induced by fendiline.
Ging Kuo Wang - One of the best experts on this subject based on the ideXlab platform.
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Prenylamine block of nav1 5 channel is mediated via a receptor distinct from that of local anesthetics
Molecular Pharmacology, 2002Co-Authors: Mustafa G Mujtaba, Shoya Wang, Ging Kuo WangAbstract:We have shown previously that Prenylamine, a calcium channel blocker, has potent local anesthetic activity in vivo and in vitro. We now characterize the tonic and use-dependent block of Prenylamine on wild-type human cardiac voltage-gated sodium channels (hNav1.5) transiently expressed in human embryonic kidney 293t cells under whole-cell voltage-clamp condition. We also determine whether Prenylamine and local anesthetics interact with a common binding site on the Nav1.5 channel by analyzing Prenylamine block on mutant hNav1.5 channels that have substitution mutations in amino acids at the putative local anesthetic binding sites. Prenylamine exhibits tonic block at both hyperpolarizing and depolarizing potentials on hNav1.5 channels with 50% inhibitory concentrations of 9.67 +/- 0.25 microM and 0.72 +/- 0.02 microM, respectively. Substitutions of the amino acids at the putative local anesthetic binding site (i.e., F1760, N1765, Y1767, and N406) with lysine had much lesser effects on Prenylamine block of the mutant hNav1.5 channels compared with local anesthetic block. The affinity of Prenylamine was reduced at most by 5.8-fold, whereas that of bupivacaine, a known local anesthetic, was reduced by as much as 68-fold compared with wild-type by the mutations at the local anesthetic receptor site. Furthermore, equilibrium results between Prenylamine-bupivacaine mixtures suggest two independent receptors. Thus, the data demonstrate that Prenylamine has both tonic and use-dependent block of hNav1.5 channels similar to that of local anesthetics, but the location of the Prenylamine binding site on hNav1.5 differs from that of the local anesthetic binding site.