Chiral sensing for amino acid derivative based on a [2]rotaxane composed of an asymmetric rotor and an asymmetric axle.

A racemic [2]rotaxane, composed of an asymmetric rotor and an asymmetric axle, formed a diastereomer with an amino acid derivative, and showed an optical response for the chiral recognition.

[3]rotaxane synthesized via covalent bond formation can recognize cations forming a sandwich structure.

A novel [3]rotaxane composed of two 25-membered crownophanes and one axle molecule having two anthryl end groups was successfully synthesized via covalent bond formation followed by aminolysis, and can incorporate caesium ion into the space between the two macrocycles as a 1 : 1 sandwich-type complex, whereas it makes a 1 : 2 complex with lithium ion.

Synthesis of [1]rotaxane via covalent bond formation and its unique fluorescent response by energy transfer in the presence of lithium ion.

Although there have been a lot of reports on the synthesis and properties of [n]rotaxanes (mainly n = 2), only a few reports on the synthesis of [1]rotaxane has been published by Vögtle's group and others (see ref 5). Generally speaking, [1]rotaxane might be expected to exhibit properties different from other rotaxanes, because the rotor and the axle in the [1]rotaxane is bound covalently and closely. We report on a novel method to make [1]rotaxanes via covalent bond formation from a macrocyclic compound.

STM-based molecular detection of "catch-and-release" of protons for bipyridine bound to phenylene-ethynylene thiol.

The protonation/deprotonation response of a novel bipyridine containing (phenylene-ethynylene) thiol adsorbed to a Au surface was investigated with scanning tunneling microscopy (STM), showing reversible changes in the average heights (approximately 50 spots) and the height distribution arising from protonation/deprotonation.

A novel crownophane trapping CO2 as carbonic acid at room temperature.

A 25 membered crownophane with two hydroxy and two amide groups around the cavity has been reported for the first time to be able to include carbonic acid formed from both carbon dioxide and water molecules to give a stable 1:1 complex at room temperature.

A novel synthesis of chiral rotaxanes via covalent bond formation.

Chiral rotaxanes composed of the asymmetric crownophane incorporating two hydroxy groups as a rotor moiety and the asymmetric axis were effectively synthesized via covalent bond formation, i.e. tandem Claisen rearrangement, esterification, and aminolysis.

First helical zinc(II) complex with a salen ligand.

The structure of a tetra-coordinated zinc(II) complex with a salen ligand was determined for the first time; unexpectedly, the complex was an interesting 2:2 metal-to-ligand complex.

Cooperative enhancement of water binding to crownophane by multiple hydrogen bonds: analysis by high level ab initio calculations.

The intermolecular interaction energy of the model system of the water-crownophane complex was analyzed. The water molecule has four hydrogen bonds, with the two hydrogen-donating phenolic hydroxy groups and two hydrogen-accepting oxygen atoms of the poly-oxyethylene chain of the crownophane in the complex. The MP2/6-311G(2d,2p) level calculations of the model system of the complex (hydrogen donating unit + hydrogen accepting unit + water) indicate that the binding energy of the water is 21.

Separation of aromatic isomers on cyclophane-bonded stationary phases.

A cyclophane (CP66)-bonded silica gel stationary phase (CP66-SP) was prepared and the retention of water-insoluble hydrophobic compounds on it was investigated in comparison with that on the CP44-bonded stationary phase (CP44-SP) reported previously. Like CP44-SP, it retained aromatic compounds more strongly than the corresponding alicyclic compounds, as was expected by the cavity size of the cyclophane. The CP66-SP also showed isomer-selectivity for monosubstituted and disubstituted naphthalenes, but its selectivity was perfectly reversed to that of the CP44-SP.

Idebenone improves learning and memory impairment induced by cholinergic or serotonergic dysfunction in rats.

The effects of idebenone, a cerebral metabolic enhancer, on learning and memory impairment in two rat models with central cholinergic or serotonergic dysfunction were investigated using positively reinforced learning tasks. A delayed alternation task using a T maze was employed to test the effect of idebenone on short-term memory impairment induced by a cholinergic antagonist, scopolamine. A correct response, defined as a turn toward the arm opposite to that in the forced run, was rewarded with food pellets.

Effects of idebenone on memory impairment induced in ischemic and embolization models of cerebrovascular disturbance in rats.

Two rat models of memory impairment in passive avoidance learning induced by cerebrovascular disturbance, were established to estimate the effects of a cerebral metabolic enhancer, idebenone. Transient and global cerebral ischemia in rats, produced by 4-vessel occlusion for 200 s immediately after the acquisition trial of passive avoidance learning, shortened the latencies in the retention test trial performed 24 h later. This retrograde amnesia was reversed significantly by idebenone administered orally or intraperitoneally at the doses of 10 and 30 mg/kg before the retention test trial.

Effects of idebenone on metabolism of monoamines and cyclic AMP formation in rats.

Idebenone, 6-(10-hydroxydecyl)-2,3-dimethoxy-5-methyl-1,4-benzoquinone, at a dose of 100 mg/kg (i.p.) markedly increased the level of 5-hydroxyindole-3-acetic acid (5-HIAA) in several brain regions without affecting monoamine contents in normal rats.

[Effect of thyrotropin-releasing hormone (TRH) and its analog DN-1417 on scopolamine-induced impairment of short-term memory in rats].

The effects of a few drugs, which are known to activate central nervous system, on scopolamine-induced impairment of short-term memory (STM) were studied in a delayed alternation task in rats. Rats were initially trained using a delayed alternation task in which a forced run to one arm of a T-maze was followed by a free-choice run. A correct free-choice response was defined as a turn toward the arm opposite to that in the forced run, and was rewarded with food pellets.

Cerebral embolization leads to memory impairment of several learning tasks in rats.

The effects of cerebral embolization, produced by injecting microspheres into the left internal carotid artery, on passive and active avoidance tasks and water filled multiple T-maze task, were studied in male Wistar rats. The rats with cerebral embolization were markedly impaired acquisition and retention of the one-trial passive avoidance response. The impairment depended on the number of microspheres injected and continued for 2 weeks.

Age-related changes in learning and memory in the senescence-accelerated mouse (SAM).

Age-related changes in learning ability were studied in senescence-accelerated mice (SAM) reared under specific pathogen-free (SPF) conditions. SAM-P/8/Ta (SAM-P/8, senescence-prone substrain) showed an age-associated increase in spontaneous motor activity (SMA) compared with SAM-R/1/Ta (SAM-R/1, senescence-resistant substrain) in a novel environment when the activity was measured in the light period, although there was no significant difference in the dark period. In observations of the circadian rhythm of SMA, SAM-P/8 showed a significant increase in diurnal SMA.

[Effect of idebenone on scopolamine-induced impairment of short-term memory in rats].

The effects of a novel compound, idebenone [6-(10-hydroxydecyl)-2, 3-dimethoxy-5-methyl-1, 4-benzoquinone] and cholinergic drug on short-term memory (STM) were studied in a delayed alternation task in rats. Rats were initially trained using a delayed alternation task in which a forced run to one arm of a T-maze was followed by a free-choice run. A correct free-choice response was defined as a turn toward the arm opposite to that in the forced run, and was rewarded with food pellets.

A possible mechanism of action of thyrotropin-releasing hormone (TRH) and its analog DN-1417 on the release of dopamine from the nucleus accumbens and striatum in rats.

Slices of the nucleus accumbens, the terminus of the mesolimbic dopaminergic system and the striatum, the terminus of the nigrostriatal dopaminergic system obtained from rats, were used for analyzing the dopamine releasing effects of TRH and its analog DN-1417 (gamma-butyrolactone-gamma-carbonyl-L-histidyl-L-prolinamide citrate). (1) Dopamine release: The addition of DN-1417 (5 X 10(-5) M) or TRH (5 X 10(-4) M) stimulated the release of prelabelled [3H]-dopamine (DA) from the superfused nucleus accumbens slices, and 100 or 20 times higher concentrations of each compound stimulated DA release from the striatal slices. The omission of Ca2+ from the superfusion medium or the addition of ouabain (5 X 10(-3) M), a (Na+ + K+) stimulated adenosine triphosphate (ATP) phosphohydrolase [(Na+ + K+)-ATPase] inhibitor, almost completely abolished the DN-1417- or TRH-induced DA releasing effect.

[Pharmacological actions of iprazochrome on the vascular system].

The pharmacological actions of iprazochrome (IC) on the vascular system were studied, and the following results were obtained: No death nor abnormal behaviors were observed in acute toxicity tests conducted on male and female mice and rats despite the administration of large doses of IC (10,000 mg/kg, p.o. and 80 mg/kg, i.

[A TRH analog (DN-1417). Antagonistic effects on reserpine-induced decreases in local cerebral glucose utilization and cerebral monoamine levels].

Thyrotropin-releasing hormone (TRH) and its analog, DN-1417 (gamma-butyrolactone-gamma-carbonyl-L-histidyl-L-prolinamide citrate), significantly antagonized against reserpine-induced reduction of the spontaneous motor activity and the electroconvulsive threshold in mice. To search for sites of action and mechanisms, effects of DN-1417 on reserpine in local cerebral glucose utilization (LCGU) and cerebral monoamine levels were also investigated in rats. Reserpine (2 mg/kg, i.

[Effect of TRH and its analog DN-1417 on anoxia-induced amnesia in mice].

The effect of neuropeptides and their analogs on anoxia-induced amnesia was examined using one-trial passive avoidance task in mice. Anoxia, produced by the exposure to CO2 immediately after the acquisition of avoidance response, induced amnesia which is shown by a short latency to enter from the safety compartment into the shocked compartment in the retention test conducted 24 hr later. In these anoxia-treated animals, thyrotropin-releasing hormone (TRH: 10-20 mg/kg), its analog DN-1417 (10-20 mg/kg) and ACTH 4-10 (66 micrograms/body), which were given sc 15-60 min before the retention test, markedly prolonged the latency in a dose-dependent manner, indicating a reversal of the amnesia.

[A TRH analog (DN-1417). Blood level and brain distribution determined by radioimmunoassay after intravenous administration in rats].

Thyrotropin-releasing hormone (TRH) and its analog, DN-1417 (gamma-butyrolactone-gamma-carbonyl-L-histidyl-L-prolinamide citrate), were administered intravenously to rats, and the blood level and brain distribution were determined by a specific radioimmunoassay. Degradation half-life of DN-1417 in the brain homogenate and blood was 27.5 min and those of TRH were 5 and 7.

[A TRH analog (DN-1417). Anti-reserpine action in electroconvulsive threshold and involvement of serotonergic (5-HT) mechanism in mice].

The antagonistic effect of a TRH (Thyrotropin-releasing hormone) analog, DN-1417 (gamma-butyrolactone-gamma-carbonyl-L-histidyl-L-prolinamide citrate) against reserpine-induced reduction of electroconvulsive threshold (EC50) and the involvement of monoaminergic mechanism were studied in mice. Reserpine (2 mg/kg, i.p.

[A TRH analog (DN-1417). Effects on the levels of monoamines and the metabolites in the various brain regions in rats].

The effects of a TRH (thyrotropin-releasing hormone) analog, DN-1417 (gamma-butyrolactone-gamma-carbonyl-L-histidyl-L-prolinamide citrate), on the levels of norepinephrine (NE), dopamine (DA), serotonin (5-HT) and the metabolites in the various brain regions of rats were determined by means of high performance liquid chromatography with electrochemical detection. DN-1417 (20 mg/kg, i.p.

[TRH and its analog (DN-1417). Effects on central dopaminergic system-dependent behaviors in rats and mice].

Effects of TRH and its analog, gamma-butyrolactone-gamma-carbonyl-histidyl-prolinamide citrate (DN-1417), on circling, stereotyped or climbing behavior were investigated in rats and mice. High doses of TRH (100 mg/kg, i.p.

[Regional cerebral blood flow in rats with cerebral ischemia produced by bilateral vertebral and carotid artery occlusion].

Regional cerebral blood flow (rCBF) was measured prior to, during and after global cerebral ischemia in rats. Global cerebral ischemia was produced by 10 or 30-min occlusion of both common carotid arteries which was done 24 hr after the permanent electrocauterization of bilateral vertebral arteries. The rCBF was measured using the radioactive microsphere technique.