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Conformational studies by dynamic NMR. 100. Enantiomerization process of stereolabile atropisomers in pyridine-substituted adamantane derivatives.

The barriers for interconverting the conformational enantiomers (stereolabile atropisomers) of pyridine-substituted adamantane derivatives have been determined by dynamic 13C NMR spectroscopy. The trend of these values parallels that anticipated by MM calculations. In at least one case, the computed structure was found to agree with that obtained by single-crystal X-ray diffraction. In addition, it has been possible to achieve a physical separation of a pair of these stereolabile atropisomers at -60 degrees C by means of the enantioselective cryogenic HPLC technique.

Journal Article↗

Rigid molecular tripod with an adamantane framework and thiol legs. Synthesis and observation of an ordered monolayer on Au111.

Tripod-shaped trithiols 1-3, containing CH2SH groups at the three bridgehead positions of the adamantane framework and a halogen-containing group [Br (1), p-BrC6H4 (2), or p-IC6H4 (3)] at the fourth bridgehead, were synthesized, and self-assembled monolayers (SAMs) were prepared on atomically flat Au111 surfaces. The three-point chemisorption of these tripods was confirmed by polarization modulation infrared reflection absorption spectroscopy, which showed the absence of a S-H stretching band. Scanning tunneling microscopy of the SAM of 1 exhibited a hexagonal arrangement of the adsorbed molecule with a lattice constant of 8.7 angstroms. A unidirectionally oriented, head-to-tail array of 1, which allows the close approach of neighboring molecules, is proposed as a reasonable model of the two-dimensional crystal, where the adsorbed sulfur atoms form a quasi-(radical3 x radical3)R30 degrees lattice. The charge of the electrochemical reductive desorption of the SAM of 1 was in good agreement with the expected surface coverage, while the SAMs of 2 and 3 showed somewhat less (ca. 70%) charge. The large negative reduction peak potentials, observed for the SAM of 1, are taken to indicate a tight anchoring of this tripod by three sulfur atoms.

Journal Article↗

Synthesis and structure of sila-adamantane.

An organosilicon cage compound containing the sila-adamantane structural unit, which is the building block of crystalline silicon, was synthesized by the Lewis acid-catalyzed rearrangement reaction of a structural isomer.

Journal Article↗

In vitro antiviral activity and preliminary clinical trials of a new adamantane compound.

A compound, 1'-methyl spiro (adamantane-2,3'-pyrrolidine) maleate, chemically related to the antiviral drug amantadine, was tested for activity in vitro against a number of human respiratory viruses. By a variety of techniques, it was shown to be active against a wide range of human and animal influenza A viruses. The effect was, however, variable and ranged from high activity against two 1957 Asian strains to no observable activity against a 1971 strain. Like amantadine, the drug did not inhibit the growth of influenza B viruses. It was also inactive against a number of paramyxoviruses. Unlike amantadine, the drug did inhibit rhinoviruses, but to a lesser extent than myxoviruses. The coronavirus 229E was also sensitive to the action of the drug in vitro. Although an earlier trial in volunteers showed that, when given orally from 2 days before until 5 days after virus challenge, the drug was protective against infection with influenza A/Hong Kong/68 virus, a similar trial in volunteers challenged with rhinoviruses 2 and 9 revealed no useful activity against rhinoviruses in man.

Animals↗

[Clinico-neurophysiologic and experimental study of the peculiarities of adamantan-sulphate treatment in Parkinson's disease].

An experimental investigation of parkinsonism in rats and patients with initial forms of Parkinson's disease was performed by using methods of electromyography and electroneuromyography. Neurophysiologic peculiarities of reorganization of peripheral neuromotor apparatus and criteria for treatment efficacy were detected. The results obtained in the study allowed evaluating of an adequacy of adamantan-sulphate therapy either in the animal experiments and in patients with Parkinson's disease.

Aged↗

An adamantane derivative (N-N'(1-adamantil)-ethylene diamine dibromide) induced automaticity in the ventricular myocardium of the frog.

The effect of an adamantane derivative (N-N'(1-adamantil)-ethylene diamine dibromid; AED) on the transmembrane potentials and contractile activity of isolated electrically driven frog ventricular strips were studied. The effect of AED on the 42K efflux in ventricular muscle rings was also investigated. AED at a concentration of 10(-3) M markedly reduced the rate of depolarization and prolonged the duration of action potential. The resting potential was shifted to less negative potential ranges and pacemaker-like action potentials appeared within 10 minutes of exposure to drug. AED was found to exert an enhancing effect on the contractile force of the frog ventricular muscle. The slow Ca2+-channel blocked D-600 was able to abolish completely the AED-induced automaticity, while the beta-adrenoceptor blocker pindolol failed to prevent this action. The pacemaker activity was reduced by increasing external K+ concentration. AED markedly reduced the 42K efflux in ventricular muscle rings. In conclusion, the AED was shown to be able to induce automaticity by decreasing the outward movement of potassium ions and by depolarizing the cell membrane.

Amantadine↗

Synthesis, antitumor activity, and anti-HIV-1 testing of certain heterocyclic systems containing an adamantane nucleus.

A new series of substituted 2-(1-adamantyl)-4H-3,1-benzoxazin-4-ones and 2-(1-adamantyl)-3-amino or alkyl-3,4-dihydroquinazolin-4-ones have been synthesized and tested for their antitumor and antiviral activities. Among the tested compounds, compounds 5a and 5b exhibited a broad spectrum antitumor activity with full panel (MG-MID) median growth inhibition (GI50) values of 3.2 and 4.9 microM respectively. Meanwhile, compounds 5c, 5d, 5h, 5i, and 5j showed moderate selectivity towards leukemia cell lines. On the other hand, compounds 4a and 4b possessed moderate Anti-HIV-1 potency with EC50 values of 50.3 and 69.2 microM respectively. Detailed synthesis, spectroscopic, and biological data are reported.

Adamantane↗

Effect of dimethylamino-2-ethoxyimino-2-adamantane (CM 54903), a non-polar dimethylaminoethanol analog, on brain regional cholinergic neurochemical parameters.

CM 54903, a new psychotropic drug with a particular pharmacological profile, produced a widespread but short-lasting decrease in acetylcholine content in rat brain hemispheric regions but not in the midbrain-hindbrain or cerebellum at the dose of 40 mg/kg, i.p. The decrease was most conspicuous in the striatum. Brian regional choline contents were unaltered as were the acetylcholine turnover rates in the striatum and hippocampus. Neither choline acetyltransferase nor acetylcholinesterase activities were altered after the in vitro incubation or the in vivo administration of high amounts of the drug. CM 54903 was found to be a competitive, reversible inhibitor of the sodium-dependent high affinity uptake of choline by crude hippocampal and striatal synaptosomal preparations showing an IC50 of 10 microM in vitro. Despite the fact that the drug readily crosses the blood-brain barrier and achieves brain concentrations several-fold greater than its in vitro IC50, CM 54903 did not inhibit choline uptake in vivo although it was capable of preventing the pentylenetetrazol-stimulated choline uptake by hippocampal synaptosomes. The changes in striatal acetylcholine content induced by the blockade or the stimulation of muscarinic cholinergic receptors or dopaminergic receptors did not interfere with the effect of CM 54903 on striatal acetylcholine content while pentylenetetrazol completely prevented the decrease. The results taken together indicate that the major effect of CM 54903 on the cholinergic neurons is at the presynaptic level to compete with choline at its uptake sites.

Acetylcholine↗

The novel GABA adamantane derivative (AdGABA): design, synthesis, and activity relationship with gabapentin.

A facile preparation of 2-aminomethyl-2-tricyclo[3.3.1.1(1,7)]decaneacetic acid hydrochloride 5 (AdGABA) is described. The synthesis of AdGABA involves the hydrogenation of 2-cyano-2-tricyclo[3.3.1.1(1,7)]decaneacetic acid 11, which was synthesized by two different synthetic routes. AdGABA was found to antagonize the pentylenetetrazole (PTZ) and semicarbazide (SCZ) induced tonic convulsions and exhibits analgesic activity in the hot plate test on mice. Although its mechanism of action is quite similar to that proposed previously for gabapentin (interaction with the alpha2delta subunit of the voltage gated Ca2+ channels), further studies were undertaken in order to clarify the precise mechanism of the anticonvulsant and analgesic effects of AdGABA on a molecular level.

Acetates↗

A novel adamantane derivative attenuates retinal ischemia-reperfusion damage in the rat retina through sigma1 receptors.

The effects of a novel N-methyladamantan-1-amine derivative [(-)-MR22] with high sigma1 receptor affinity were investigated on retinal degeneration using a rat model of ischemia-reperfusion injury. The animals were anaesthetized and retinal ischemia was induced by elevating the intraocular pressure to 120 mm Hg for 45 min. The drug was injected intraperitoneally before the ischemic damage. Retinal biochemical changes, i.e. increase of lactate content and decrease of glucose and ATP were significantly inhibited by the new and selective sigma1 receptor ligand compared to the ischemic control group. The effect of (-)-MR22 was antagonized by pre-treatment with the sigma1 site antagonist. The protective effect of (-)-MR22 on ischemic retina was confirmed by the histological analysis. These findings suggest that (-)-MR22 serves as a retinal neuroprotective agent and acts as a sigma1 receptor agonist.

Adamantane↗