• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.2938-2942
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• 2009

New receptors 1-3 that bind stereoselectively amino alcohols and convert chirality of amino acidsvia imine bond formation were synthesized. The receptors have uryl (1), thiouryl (2) and guanidinium (3) groups all with additional phenylcarbonyl motifs, which are effective hydrogen bonding donors and play a key role in the stereoselective recognitions. The stereoselectivities were measured from the integration of $^1HNMR$ peaks. Compound 1 and 2 showed the stereoselectivities for the imine formation with amino alcohols ($K_R/K_S$) in the range of 2${\sim}$4, and compound 3 in the range of 4${\sim}$8. Chirality conversion efficienciesof 1-3 for amino acids, i.e. D/L ratio at equilibrium, are in the range of 1.5${\sim}$5.6, showing a little higher efficiency with 3. The additional phenylcarbonyl motifs in 1-3 were revealed not to contribute to significant enhancement of the selectivities.

• Bulletin of the Korean Chemical Society
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• 제35권7호
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• pp.2025-2028
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• 2014

Anion receptor 1 based on acylhydrazone has been designed and synthesized. UV-vis and $^1H$ NMR titration showed that receptor 1 is selective receptor for dihydrogen phosphate ($H_2PO_4{^-}$). Dihydrogen phosphate was complexed by the receptor 1 via at least 4 hydrogen bonding interactions, contributing from two amide N-Hs and two imine C-Hs. In addition, nitrogen in the aromatic ring could make 2 additional hydrogen bondings with OH groups in the dihydrogen phosphate. However, the receptor 1 could make only 4 hydrogen bonds with halides. Therefore, receptor 1 could bind anions through hydrogen bonds with a selectivity in the order of $H_2PO_4{^-}$ > $Br^-$ > $Cl^-$ in highly polar solvent such as DMSO.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1289-1294
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• 2010

Novel $H_8$-binaphthol-based chiral receptors appended with an uryl moiety (2a) and a guanidinium moiety (2b) have been designed and synthesized for the enantioselective recognition of 1,2-amino alcohols via reversible imine formation. The selectivities ($K_R/K_S$ = 9.8 ~ 19.4) of 2b in imine formation with 1,2-amino alcohols are higher than those of 2a ($K_R/K_S$ = 1.8 ~ 4.5). Similar efficiency trend have been observed in the conversion of L-amino acids to D-amino acids, i.e., the efficiency of the receptor 2b (D/L ratio: 4.3 ~ 10.1) is superior to 2a (D/L ratio: 4.0 ~ 8.7).

• Bulletin of the Korean Chemical Society
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• 제30권2호
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• pp.409-414
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• 2009

Novel binol aldehydes derivatized at 2' hydroxy position with both uryl and acetamide groups (2), and diuryl groups (3) have been synthesized. Both were designed for streospecific binding and chirality conversion of general dipeptides with support of multiple hydrogen bonding donor sites in the receptors. The receptors, 2 and 3, converted the chirality of N-terminal amino acids of peptides such as Ala-Gly, Met-Gly, Leu-Gly and His-Gly with stereoselectivity on D-form over L-form. The stereoselectivity ratios were in the range of 5-11, somewhat higher than those of the binol receptor with mono uryl group (1). The DFT calculation at the B3LYP/6-31G$^*$//MPWB1K/6-31G$^*$ level revealed that 3-D-Ala-Gly was 2.2 kcal/mol more stable than 3-L-Ala-Gly. The considerable steric hindrance between the methyl group of the alanine and the imine CH moiety of the receptor seems to be the main contributing factor for the thermodynamic preference.

• Archives of Pharmacal Research
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• 제24권6호
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• pp.503-507
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• 2001

trans-Metanicotine, a subtype (${\alpha}_4{\beta}_2$)-selective ligand for neuronal nicotinic acetylcholine receptor, is under clinical phase for Alzheimer's disease. An efficient synthetic route for ($\pm$)-methyl-(1-aryl-4-pyridin-3-yl-but-3-enyl)-am ices, derivatives of tracts-metanicotine, was explored. Allylation reaction of aryl aldimines with allylmagnesium bromide in THF gave ($\pm$)-methyl-(1-aryl-but-3-enyl)-amines. Protection of the amines with the Boc group and following Heck reaction of the N-Boc amines with 3-bromopyridine gave ($\pm$)-methyl-(1-aryl-4-pyridin-3-yl-but-3-enyl)-carbamic acid tert-butyl esters. Deprotection of the N-Boc group in aqueous 1 N-HCI solution gave the titled amines in good yields. Thus, trans-metanicotine analogues modified at the ${\alpha}-position$ of the methylamino group with amyl groups were obtained in 5 steps.

• Journal of Periodontal and Implant Science
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• 제41권1호
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• pp.17-22
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• 2011

Purpose: Nitric oxide (NO) has been known as an important regulator of osteoblasts and periodontal ligament cell activity. This study was performed to investigate the relationship between NO-mediated cell death of human periodontal ligament fibroblasts (PDLFs) and N-methyl-D-aspartic acid (NMDA) receptor antagonist (+)-5-methyl-10, 11-dihydro-5H-dibenzo[a,d]cyclohepten-5, 10-imine hydrogen maleate (MK801). Methods: Human PDLFs were treated with various concentrations (0 to 4 mM) of sodium nitroprusside (SNP) with or without $200\;{\mu}M$ MK801 in culture media for 16 hours and the cell medium was then removed and replaced by fresh medium containing MTS reagent for cell proliferation assay. Western blot analysis was performed to investigate the effects of SNP on the expression of Bax, cytochrome c, and caspase-3 proteins. The differences for each value among the sample groups were compared using analysis of variance with 95% confidence intervals. Results: In the case of SNP treatment, as a NO donor, cell viability was significantly decreased in a concentration-dependent manner. In addition, a synergistic effect was shown when both SNP and NMDA receptor antagonist was added to the medium. SNP treated PDLFs exhibited a round shape in culture conditions and were dramatically reduced in cell number. SNP treatment also increased levels of apoptotic marker protein, such as Bax and cytochrome c, and reduced caspase-3 in PDLFs. Mitogen-activated protein kinase signaling was activated by treatment of SNP and NMDA receptor antagonist. Conclusions: These results suggest that excessive production of NO may induce apoptosis and that NMDA receptor may modulate NO-induced apoptosis in PDLFs.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.1985-1989
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• 2013

A simple colorimetric and fluorescent anion sensor 1 based on salicylimine showed a high selectivity and sensitivity for detection of cyanide in aqueous solution. The receptor 1 showed high selectivity toward $CN^-$ ions in a 1:1 stoichiometric manner, which induces a fast color change from colorless to orange and a dramatic enhancement in fluorescence intensity selectively for cyanide anions over other anions. Such selectivity resulted from the nucleophilic addition of $CN^-$ to the carbon atom of an electron-deficient imine group. The sensitivity of the fluorescence-based assay (0.06 ${\mu}M$) is below the 1.9 ${\mu}M$ suggested by the World Health Organization (WHO) as the maximum allowable cyanide concentration in drinking water, capable of being a practical system for the monitoring of $CN^-$ concentrations in aqueous samples.