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Modulation of glycine-activated membrane current by adamantane derivatives.

Pressure application of the inhibitory neurotransmitters glycine and GABA, respectively, evoked a Cl- current in spinal cord neurons of fetal mice in culture. Memantine, in low concentrations (0.3-5 microM) enhanced the glycine-mediated current at both negative and positive holding potentials. At concentrations of more than 5 microM, memantine increased the glycine-evoked current only when the membrane potential was positive. At negative potentials the current was inhibited. 3-isopropylamantadine and 3,5-diethylamantadine augmented the glycine-activated membrane current irrespective of the concentrations applied, whereas amantadine was ineffective. The GABA-activated Cl- current was not altered by the adamantanes. These data are evidence of a specific glycinergic interaction with putative antispastic agents and can explain some conflicting effects of memantine in experimentally induced seizures.

Adamantane↗

An epoxide hydrolase inhibitor, 12-(3-adamantan-1-yl-ureido)dodecanoic acid (AUDA), reduces ischemic cerebral infarct size in stroke-prone spontaneously hypertensive rats.

Soluble epoxide hydrolase (sEH) inhibitors have been demonstrated to have cardiovascular protective actions. This hydrolase enzyme converts fatty acid epoxides to their corresponding diols, and this conversion can alter the biologic activity of these metabolites. We hypothesized that 12-(3-adamantan-1-yl-ureido)dodecanoic acid (AUDA), a sEH inhibitor, would protect stroke-prone spontaneously hypertensive rats from cerebral ischemia. AUDA was administered to 6-week-old male rats for 6 weeks, during which blood pressure was measured by telemetry. Cerebral ischemia was induced by middle cerebral artery occlusion, the size of the cerebral infarct was assessed after 6 hours of ischemia, and the results were expressed as a percentage of the hemisphere infarcted (%HI). Vascular structure and function were assessed using a pressurized arteriograph. Plasma levels of AUDA at the end of the treatment period averaged 5.0 +/- 0.4 ng/mL, and the urinary excretion rate was 99 +/- 21 ng/d. AUDA-treated rats had significantly smaller cerebral infarcts than control rats (36 +/- 4% vs 53 +/- 4% HI, treated versus control, P < 0.05, n = 6). This difference occurred independently of changes in blood pressure. AUDA treatment increased the passive compliance of the cerebral vessels but had no effect on vascular structure. The results of this study provide novel evidence suggesting that the sEH inhibitor AUDA is a possible therapeutic agent for ischemic stroke.

Adamantane↗

[Inhibitory effect of alpha-methyl-1-adamantane methylamine hydrochloride (rimantadine) on RNA-dependent RNA polymerase induction in culture of cells, infected with influenza virus].

An anti-influenza preparation, rimantadine (alpha-methyl-1-adamantane methylamine hydrochloride) at concentrations of 10--25 mkg/ml depresses the RNA-dependent RNA polymerase induction in a culture of cells infected with influenza virus (fowl plague virus). The inhibitory effect is also observed 2 hours following cell infection. In vitro studies have demonstrated that rimantadine has no effect on the activity of virus-induced RNA-dependent RNA polymerase, as well as on that of RNA-dependent RNA polymerase associated with virus particles.

Adamantane↗

Molecular size and hydrophobicity as factors which determine the efficacy of the blocking action of amino-adamantane derivatives on NMDA channels.

Neurons isolated from the CA-1 region of rat hippocampal slices by the "vibrodissociation" method were voltage-clamped in the whole cell configuration. The currents through NMDA channels were recorded in response to rapid application (solution exchange time <30 ms) of 100 microM aspartate (ASP) in a Mg2+-free solution in the presence of 3 microM glycine. When added to the ASP solution, amantadine as well as other amino-adamantane derivatives (AAD) produced an open-channel blockade of NMDA channels. Membrane hyperpolarization enhanced the AAD block. The affinity between NMDA channels and AAD was different for various AAD. The analysis of the experimental data led us to conclude that this affinity depended both on the molecular size of the blocker (calculated using HyperChem molecular modeling program) and on the blocker's hydrophobicity (calculated according to Hansch and Leo, 1979). The affinity between NMDA channels and AAD diminished with an increase in molecular size and raised with an increase in blocker's hydrophobicity. We propose an empirical equation which describes the dependence of affinity on the size and hydrophobicity of the blocker. The estimated critical diameter of the NMDA channel pore where the AAD blocking site is located proved to be about 17 A.

Adamantane↗

Synthesis and antimicrobial activity evaluation of some new adamantane derivatives.

In this study, some new Schiff bases were synthesized as antimicrobial agents using benzaldehyde derivatives and 1- or 2-aminoadamantane. The structures of the synthesized compounds were confirmed by IR, 1H-NMR and elementary analysis. Antimicrobial activities of the synthesized compounds were tested against some bacteria and yeast-like fungi. The antimicrobial activity of the compounds was investigated by broth microdilution method using two Gram positive (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212) and two Gram negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853) bacteria and yeast-like fungi (Candida albicans ATCC 90028, Candida krusei ATCC 6258, Candida parapsilosis ATCC 22019). The antifungal activity of 1-((2-chloro-3,4-dimethoxybenzylidene) amino(adamantane (compound 3) against C. krusei and C. parapsilosis (minimal inhibitory concentration 32 micrograms/ml) was higher than that of the other tested compounds.

Adamantane↗

[Comparative study of neurophysiological effects of adamantane derivatives in the experimental parkinsonism model].

The activity of the adamantane derivative PK-Merz and the new aminoadamantane derivative hemantane was studied by methods of electromyography and electroneuromyography in rats with a model of Parkinson syndrome induced by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The toxin produced an increase in the pulse conduction velocity (PCV) in the motor fibers of peripheral nerves and a decrease in the amplitude and frequency of the maximum muscle stress curve. A singe administration of both PK-Merz and hemantane produced unidirectional changes in the neuromyographic parameters and reduced the PCV down to a level in the control group. These results give ground for the clinical investigation of hemantane.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

[Antiviral action of membranotropic compounds modified by adamantane and norbornene pharmacophores exerted on different HIV-1 strains].

The anti-HIV activity of new membranotropic compounds, i.e. of the polycarboxylate matrix and of its derivatives modified by adamantane and norbonene, was studied in respect of HIV-1 strains, whose tropicity to coreceptors CCR5 and CXCR4 was different, as well as in respect of HIV-1 variants resistant to azidothymidine (AZT) in a continuous culture of human lymphoid cells (MT-4) and in mononuclear cells of peripheral blood from healthy donors. Testing of complex compounds in a culture of infected MT-4 human lymphoid cells showed an effective inhibition of viral reproduction of LAV.04 (CXCR4-tropic variant) and of HIV11(EVK) as well as AZT-resistant variants. The studied pharmacophores-modified compounds displayed, in infection of the primary culture of human mononuclear cells of the HIV-1 R5 and X4 strains, a notable antiviral activity with their HIV efficiency significantly exceeding the one of the original matrix.

Adamantane↗

[Antiviral chemotherapeutic agents. XVIII. Adamantane derivatives of amphetamine. Their potential interest as autonomic and antiparkinson agents].

Adamantane isologs of amphetamine, methamphetamine and pheniprazine and several derivatives were synthesized in order to study the influence of their more pronounced lipophilic characteristics on their biological properties. A preliminary examination of their toxicity, antiviral, CNS stimulant and antiparkinson activity is described. The adamantyl amphetamine, which proved active, will be further studied.

Adamantane↗

Purification of rat liver microsomal cytochrome P-450 by chromatography on immobilized adamantane with a new method of detergent removal.

A method for the isolation of liver microsomal cytochrome P-450 from phenobarbital-treated rats is described which is based on chromatography on 1-adamantane-carbonyl-aminohexyl-Sepharose 4B, subsequent ion exchange chromatography on DEAE-cellulose and detergent removal by adsorption on silica gel G. The method gives preparations with high electrophoretic homogeneity which correspond to a major phenobarbital-inducible form of rat liver microsomal cytochrome P-450. The advantages of the procedure described are high yields, stability of chromatographic material, effective and simple method of detergent removal.

Adamantane↗

[The molecular mechanism of the action of antiviral preparations in the adamantane series].

Regions of possible interaction between remantadine and transmembrane M2 protein are revealed by analysis of amino acid substitutions in remantadine- and deutiforin-resistant influenza viruses. The major region includes 5-6 amino acid residues at position 25-31, partially involving the premembrane region and the first position of a hydrophobic membrane-associated domain. The proposed model action of remantadine and its derivatives suggests that remantadine is included into the cell membrane lipid bimolecular layer by its adamantane share and its positively charged NH2-group is exposed to the cell surface. This allows remantadine and its analog to be regarded as molecular "hindrances" for viral particle decapsidation and budding.

Adamantane↗

Effect of adamantane derivatives on the activity of orthomyxovirus RNA-dependent RNA polymerase.

The effect of several adamantane derivatives on the activity of virion-associated RNA-dependent RNA polymerase of fowl plague virus (FPV) and influenza B virus was studied in vitro. Some of the derivatives inhibited the activity of the polymerase by 60 per cent. A correlation was established between the previously demonstrated capacity of these inhibitors to suppress orthomyxovirus reproduction in vivo and their ability to reduce the activity of virion-associated RNA-dependent RNA polymerase in vitro.

Adamantane↗

6-(2-adamantan-2-ylidene-hydroxybenzoxazole)-O-sulfamate: a potent non-steroidal irreversible inhibitor of human steroid sulfatase.

We report the synthesis and results from the in vitro evaluation of 6-(adamantan-2-ylidene-hydroxybenzoxazole)-O-sulfamate 1 as an irreversible inhibitor of human steroid sulfatase (STS). Highly straightforward, condensation of 2-methyl-6-hydroxybenzoxazole with 2-adamantanone, subsequent elimination of water and sulfamoylation provide the title compound in 45% overall yield from the inexpensive 2,4-dihydroxyacetophenone. 1 was found to be a potent irreversible inhibitor of purified human steroid sulfatase (STS) and specific for this enzyme relative to human arylsulfatases A and B. In cellular assays with human keratinocytes, sebocytes and fibroblasts, 1 blocked STS activity with IC(50) values in the range of 0.15-0.8 nM, and in MCF-7 breast cancer cells with IC(50)=2.3 nM, while it did not bind to estrogen receptors alpha and beta. Thus, 1 is a candidate for further investigation of its potential as a drug to be used in androgen- and estrogen-dependent diseases.

Enzyme Inhibitors↗

On the choice of optimal methodology for calculation of (13)C and (1)H NMR isotropic chemical shifts in cagelike systems. Case studies of adamantane, 2-adamantanone, and 2,4-methano-2,4-dehydroadamantane.

The (13)C and (1)H isotropic chemical shift values computed at HF, BLYP, B3LYP, and MPW1PW91/6-311+G(2d,p) levels of theory, for the BLYP and B3LYP/6-31G(d,p) optimized geometries of adamantane, 2-adamantanone, and 2,4-methano-2,4-dehydroadamantane ([3.1.1] propellane) are reported and compared with the experimental data. Except for the "inverted" carbon atoms and some of their nearest neighbors, the HF values are superior over the DFT ones, when the isotropic shifts with respect to TMS are in question. However, in case of the relative shifts computed with respect to the most deshielded center within the molecule, the DFT methods yield significantly better agreement with the experimental data than the HF method, the hybrid DFT methods being superior over "pure" DFT ones. The most probable reason for these findings may be the cancellation of errors arising from the inappropriate description of the paramagnetic contributions to the overall shielding tensor within the Kohn-Sham approach when an internal standard (within a molecule) is chosen, instead of an external one. Almost excellent linear correlation was found between the calculated and experimental relative shift values, which is significantly superior at DFT levels than at HF level, further proving the more systematical nature of errors in predicting the second-order magnetic response properties at DFT levels of theory. Among all DFT methods employed, the MPW1PW91 showed the best performance, in line with the significantly improved long-range behavior of this functional, as compared to the B3LYP one.

Journal Article↗

Adamantane-like cluster complexes of mixed-valent copper-copper and nickel-copper thiolates.

Square-planar copper(II) and nickel(II) derivatives of the cis-dithiolate N(2)S(2) ligand bis(N,N'-2-mercapto-2-methylpropyl)-1,5-diazocyclooctane, (bme*daco)M, nucleate four Cu(I)Cl moieties, forming M(II)(2)Cu(I)(4)S(4) clusters with unusual triply bridging thiolates, mu(3)-SR, in the topological form of adamantane. As determined by X-ray crystallography, the (bme*daco)M (M = Cu or Ni) metallothiolate serves as a bidentate ligand that bridges four Cu(I) ions, utilizing all lone pairs on sulfurs. Further characterization by electrochemical and electronic spectral measurements suggests greater electron delocalization in the all-copper complex as compared to the NiCu heterometallic complex. Mass spectral data imply that the mixed-metal Ni(II)(2)Cu(I)(4)S(4) is more stable toward CuCl loss than Cu(II)(2)Cu(I)(4)S(4), a result that is corroborated by extraction of Cu(I) by 1,2-bis(diphenylphosphino)ethane in the latter but not the former.

Journal Article↗

Ag3SnCuP10: [Ag3Sn] tetrahedra embedded between adamantane-type [P10] cages.

Ag3SnCuP10 was synthesized from a stoichiometric mixture of copper, silver, tin, and red phosphorus, with SnI4 added as a mineralization agent. Cubic Ag3SnCuP10, space group F3m (No. 216) with lattice parameter a = 10.503(1) A and Z = 4, consisting of orientationally disordered [Ag3Sn] heteroclusters and adamantane-type [P10] cages, is one example in which structure determination was possible only by the combined use of diffraction and spectroscopic methods. An ideal 4-fold domain twin structure that results for a R3m model, featuring an ordered arrangement of the heteroclusters, cannot be differentiated from the F3m model by diffraction methods alone. After a detailed NMR spectroscopic examination using state of the art solid-state NMR techniques, we found the local environment around the [P10] cages of the F3m model to be the correct description of the Ag3SnCuP10 structure. A possible Cu/Ag or Ag/Sn disorder in the [Ag3Sn] heterocluster and within the copper substructure was excluded by Mössbauer spectroscopic investigations and NMR measurements.

Journal Article↗

Homoconjugation in the adamantane cage: DFT/IGLO studies of the 1, 3-dehydro-5-adamantyl cation, its isoelectronic boron analogue 1, 3-dehydro-5-boraadamantane, and related systems(1)(,)

The structure of 1,3-dehydro-5-adamantyl cation and its isoelectronic boron analogue 1,3-dehydro-5-boraadamantane as well as some related adamantane systems, hitherto unknown as persistent long-lived species, were investigated by using the density functional theory (DFT) method. (13)C and (11)B NMR chemical shifts of the compounds were also calculated using the IGLO method. Stabilization of the systems due to homoconjugation is discussed.

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