• Bulletin of the Korean Chemical Society
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• v.28 no.1
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• pp.77-80
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• 2007

As neurofilament proteins are major cytoskeletal components of neuron, abnormality of neurofilament is proposed in brain with neurodegenerative disorders such as Parkinson's disease (PD). Since oxidative stress might play a critical role in altering normal brain proteins, we investigated the oxidative modification of neurofilament-L (NF-L) induced by the reaction of cytochrome c with H2O2. When NF-L was incubated with cytochrome c and H2O2, the protein aggregation was increased in cytochrome c and H2O2 concentrationsdependent manner. Radical scavengers, azide, formate and N-acetyl cysteine, prevented the aggregation of NFL induced by the cytochrome c/H2O2 system. The formations of carbonyl group and dityrosine were obtained in cytochrome c/H2O2-mediated NF-L aggregates. Iron specific chelator, desferoxamine, prevented the cytochrome c/H2O2 system-mediated NF-L aggregation. These results suggest that the cytochrome c/H2O2 system may be related to abnormal aggregation of NF-L which may be involved in the pathogenesis of PD and related disorders.

• Archives of Pharmacal Research
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• v.20 no.3
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• pp.218-224
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• 1997

Platelet-activating factor (PAF) acetylhydrolase, which removes the acetyl moiety at the sn-2 position, has been found in human amniotic fluid. We purified this enzyme by ammonium sulfate precipitation, and sequential use of DEAE-Sepharose CL-6B, hydroxyapatite, chelating-Sepharose, and Mono Q column chromatographies. This enzyme exhibited broad pH optima and was unaffected by EDTA. Partially purified enzyme had a molecular weight of approximately 34 kDa on SDS-PAGE. In addition, the enzyme activity was inhibited by either diisopropylfluorophosphate(DFP) or p-bromophenacylbromide (p-BPB), suggesting that this enzyme possesses active serine and histidine residues. The enzyme showed similar activity towards PAF and oxidatively modified phosphatidylcholine, but didn't hydrolyze phosphatidylcholine or phosphatidylethanolamine with a long chain fatty acyl group at sn-2 position.

• Journal of the Korean Chemical Society
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• v.32 no.4
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• pp.371-376
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• 1988

Thebaine was reacted with diisopropyl azodicarboxylate to give northebaine. Diels-Alder reaction between the compound and nitrosobenzene was attempted. The hydrogen of the adducted northebaine was substituted with chloroacetyl chloride and succinic anhydride. We have synthesized the new thebaine derivatives with phenylhydroxylamine at 14-carbon and also acetyl or succinyl at 17-nitrogen with yields of 22% and 16%.

• Archives of Pharmacal Research
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• v.18 no.3
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• pp.195-202
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• 1995

The thio, thio acetyl, oxime, and several hydrazone and azine derivatives of the antitumor alkaloid acronycine (1) were prepared. NMR spectroscopy was used to study the configurations around the C=N double bond in these acronycine derivatives. In the hydrazones and azines of acronycine the N-N bond assumes a syn configuration to the $C_6-OCH_3$ group, while the NO bond in the oxime and the N-N bond in noracronycine hydrazone and azines assumes an anti configuration.

• Archives of Pharmacal Research
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• v.22 no.6
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• pp.619-623
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• 1999

$2^{l},3^{l}$-dideoxyisoguanosine was synthesized from guanosine via intermediate 6-[(4-methyl-phenyl)thio]-2-oxo-9-($2^{l},3^{l},5^{l}$-tri-O-acetyl-$\beta$-D-ribofuranosyl)-2,3-dihydropurine (4). The 2-oxo, 6-amino and $5^{l}$-hydroxy triprotected isoguanosine derivative was utilized to reduce high polarity and promote poor solubility of intermediates. The protecting groups for oxo and 6-amino were easily removed in reduction of olefin in ribose without additional reaction steps.$2^{l},3^{l}$-Vicinal diol in ribose sugar moiety was transformed to olefin with Bu3SnH by radical reaction via bisxanthate. Removing $5^{l}$-O-TBDMS protecting group gave final product, $2^{l},3^{l}$-dideoxyisoguanosine (12) in a 10% overall yield.

• Bulletin of the Korean Chemical Society
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• v.15 no.6
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• pp.483-488
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• 1994

Tetra acyl esters of p-tert-butylcalix[4]arene and calix[4]arene, including acetyl, propionyl, butyryl and isobutyryl, are synthesized and their conformations are inferred from $^1H-NMR$ and $^{13}C-NMR$ spectra. The conformer distribution is affected by the presence of t-butyl group, whereas the acylation products of p-t-butylcalix[4]arene are the cone conformers, those of calix[4]arene are mostly partial cone and/or 1,3-alternate conformers. The conformational outcome is also affected by the method of preparation, the NaH-induced reaction is prefered to the acid-induced reaction for cone and partial cone. Interestingly, 1,2-alternate conformer was isolated in 14% yield from the butyrylation of calix[4]arene.

• Bulletin of the Korean Chemical Society
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• v.12 no.5
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• pp.525-529
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• 1991

A simple route is described for the selective functionalization of calixarene at the para positions of phenyl rings. Calix[4]arene tetraacetate 2, obtained from the treatment of calix[4]arene with acetic anhydride, undergoes Fries rearrangement to yield the diametrically para substituted p-diacetylcalix[4]arene 3 in 80% yield. The crystal and molecular strucutre has been determined by X-ray diffraction method. The crystals are orthorhombic, space group Pna21, with a = 11.121 (3), b = 10.374 (3), c = 21.690 (6) $\AA$ and Z = 4. The structure was solved by direct method and refined by full-matrix least-squares methods to final R of 0.036 for 1795 observed reflections. Each hydroxyl hydrogen atom is disordered over two positions. The macrocycle exists in the cone conformation which is determined by the strong circular intramolecular flip-flop type hydrogen bonds of phenolic OH, while crystal packing effects of the diametrically para-acetyl substituents seem to be responsible for the distortion of the cone conformation.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.189.1-189.1
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• 2003

4-(4-Methoxyphenyl)-2-aminothiazole and 3-(4-methoxyphenyl)-5-aminothiadiazole derivatives have been synthesized and evaluated as selective antagonists for human adenosine A$_3$ receptors. A methoxy group in the 4-position of the phenyl ring and N-acetyl or propionyl substitutions of the aminothiazole and aminothiadiazole templates displayed great increases of binding affinity and selectivity for human adenosine A$_3$ receptors. The most potent A$_3$ antagonist of the present series, N-［3-(4-methoxy-phenyl)-［1,2,4］thiadiazol-5-yl］-acetamide exhibiting a K$\_$i/ value of 0.79 nM at human adenosine A$_3$ receptors, showed antagonistic property in functional assay of cAMP biosynthesis involved in one of the signal transduction pathways of adenosine A$_3$ receptors. (omitted)

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.156-171
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• 1992

Chitin was isolated from crab shell. Chitosan, which was prepared by the deacetylation of chitin, was acylated to obtain N-acetyl(regenerated chitin), N-propionyl, N-butyryl, N-hexanoyl, N-decanoyl and N-maleated chitosans and their metal ion adsorption characteristics of N-acylchitosans were investigated. In order to enhance the adsorptivity, their porous beads were prepared and their adsorptivity with respect to the porosity and the adsorptivities for metal ions($Cu^{2+}$, $Ni^{2+}$, $CO^{2+}$, $Mn^{2+}$, $Ag^{+}$)were investigated. Their metal ion adsorptivities were remarkably imporved compared to those of chitin. As the larger acyl groups were introduced, adsorptivity increased, but that of N-decanoyl chitosan showed some decrease because of steric hindrance of the bulky N-decanoyl group. N-Maleated chitosan containing carboxyl group showed highly improved adsorptivity, and N-acylchitosans showed the good selective adsorption in the mixed metal ions($Cu^{2+}$, $Ni^{2+}$, $CO^{2+}$, $Mn^{2+}$ and $Ag^{+}$). They also showed excellent adsorption characteristics as chelating polymers.

• Natural Product Sciences
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• v.26 no.2
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• pp.165-170
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• 2020

Carica papaya is a medicinal and fruit plant owing biological activities including antioxidant, antiviral, antibacterial and anticancer. The present study aims to investigate the acetyl (AChE) and butyryl (BChE) cholinesterase inhibitory potentials of C. papaya extracts as well as their chemical compositions. The chemical composition of the active extract was identified using a gas chromatography-mass spectrometry (GC-MS). Ellman enzyme inhibition assay showed that the alkaloid-enriched leaf extract of C. papaya possessed significant anti-BChE activity with an enzyme inhibition of 75.9%. GC-MS analysis showed that the alkaloid extract composed mainly the carpaine (64.9%) - a major papaya alkaloid, and some minor constituents such as aliphatic hydrocarbons, terpenes and phenolics. Molecular docking of carpaine revealed that this molecule formed hydrogen bond and hydrophobic interactions with choline binding site and acyl pocket. This study provides some preliminary findings on the potential use of C. papaya leaf as an herbal supplement for the prevention and treatment of Alzheimer's disease.