• Applied Biological Chemistry
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• v.42 no.3
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• pp.252-255
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• 1999

Inhibition activities$(pI_{50})$ of chalcone derivatives as substrate with farnesyl protein transferase(FPTase) were determined in vitro. The structure activity relationships(SAR) between the activity and physicochemical parameters of X & Y-substituents on the phenyl groups were analyzed by Free-Wilson and Hansch method. X-substituents on the benzoyl group have the more important role to inhibition activity than Y-substituents on the styryl group. Among them, none substituent, 8 showed the highest FPTase inhibition activity$(pI_{50}=4.30)$. Particularly, the SAR equation could be formulated, showing a parabolic relationship between the activity and hydrophobicity(logP) where the optimal value$({\Sigma}logP)_{opt}$ was 3.915. And also the activity depends on the steric effect(Es > 0) with X-substituent and the resonance effect(R < 0) with electron donating Y-substituents. Based on the results of SAR analyses, the interactions between substrates and receptor, FPTase, could be assumed.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1884-1890
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• 2011

A series of Ni(II) and Pd(II) complexes bearing N4-type tetradentate ligands, [Ni($X^1X^2$-6-$Me_2bpb$) 1] and [Pd($X^1X^2$-6-$Me_2bpb$) 2]; 6-$Me_2bpb$ = N,N'-(o-phenylene)bis(6-methylpyridine-2-carboxamidate), $X^1$ = Cl, H, or $CH_3$, $X^2$ = $NO_2$, Cl, F, H, $CH_3$, or $OCH_3$) were designed, synthesized, and characterized to investigate electronic and steric effects of ligand on the norbornene polymerization catalysts. Using modified methylaluminoxanes as an activator, the complexes exhibited high catalytic activities for the polymerization of norbornene and the nickel complexes exhibited better catalytic activity the palladium complexes. Ni complex 1a with $NO_2$ group on the benzene ring showed the highest catalytic activity of $4.9{\times}10^6$ g of PNBEs/$mol_{Ni}{\cdot}h$ and molecular weight of $15.28{\times}10^5$ g/mol with PDI < 2.30. Complexes with electron-withdrawing groups are more thermally stable (> 100 $^{\circ}C$), and tend to afford higher polymerization productivities than the ones having electron-donating groups. Amorphous polynorbornenes were obtained with good solubility in halogenated aromatic solvents. A vinyl addition mechanism has been proposed for the catalytic polymerization.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.1
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• pp.45-51
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• 2014

Scuticociliates are regarded as serious pathogens in marine aquaculture worldwide. In Korea, they cause mass-mortalities in fish such as the commercially important olive flounder Paralichthys olivaceus. In particular, mixed infections of scuticociliates with pathogenic bacteria have been commonly reported. During efforts to identify natural marine-algae derived products that possess anti-bacterial and anti-scuticociliate properties, we found that an 80% methanolic extract of the red alga Polysiphonia morrowii Harvey exhibits both anti-scuticociliate activity against Miamiensis avidus, which is a major causative agent of scuticociliatosis, and anti-bacterial activities against fish pathogenic bacteria. Activity-guided fractionation and isolation of the 80% methanolic extract of P. morrowii yielded three bromophenols, which were identified as 3-bromo-4,5-dihydroxybenzyl methyl ether (1), 3-bromo-4,5-dihydroxybenzaldehyde (2) and urceolatol (3) based on spectroscopic analyses. 3-bromo-4,5-dihydroxybenzyl methyl ether (1) showed the highest anti-bacterial and anti-scuticociliate activities, with a minimal inhibitory concentration (MIC) of $62.5{\mu}g/mL$ (against Vibrio anguillarum) and minimal lethal concentration (MLC) of 62.5 ppm (in seawater). Investigations of the anti-bacterial and anti-scuticociliate activities of seventeen bromophenol derivatives, including the three isolated natural bromophenols, showed that the existence of an electron donating group or atom with a non-covalent electron pair at $C_4$ of the 2-bromophenol structure may be important in anti-scuticociliate activity. These findings suggest that the extract and bromophenol derivatives of P. morrowii may provide useful alternatives in aquaculture anti-scuticociliate therapies.

• Polymer(Korea)
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• v.26 no.1
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• pp.18-27
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• 2002

Poly(ο-hydroxyamide)s as polybenzoxazoles precursors were synthesized by polycondensation from 2,2'-bis(3-amino-4-hydroxyphenyl) hexafluoropropane and various bis-acids. And the polymers were modified to acid-sensitive polyamides by introducing tetrahydropyran in order to impart photosensitivity. A study of optical transmittance at 365 nm, according to the chemical structure of bis-acid, revealed that the polymer derived from 4,4'-oxydibenzoic acid showed better optical transparency than those from other bis-acids. This tendency of optical transmittance could be explained by formation of charge transfer complex. In case of the polymer derived from 4,4'-oxydibenzoic acid, the electron accepting characteristic of bis-acid is reduced by introduction of electron donating group, -O-. Thus, optical transmittance increased due to the diminished formation of intramolecular charge transfer complex. In addition, the optical transmittance increased with increasing the THP content in the polymer. This is attributed to the reduced intermolecular interaction by the loosening of the packing density of the polymer chain.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.446-452
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• 1992

The rates of hydrolysis of aryl phenylacetates have been measured in the presence of piperidine in 80% acetonitrile-20% water(v/v). For the electron withdrawing substituents of leaving group, the hydrolysis is catalyzed by a general base and the Hammett $\rho_{LG}$ and Bronsted value $\beta$ are 5.28 and -2.72 at $30^{\circ}C$, respectively. These high senstivities of Hammett and Bronsted values are $E1_{C}B$ mechanism. But in the electron donating ones, the hydrolysis is catalyzed by a specific base and $B_{AC}2 mechanism is predominated. $pK_{SH}'s of phenylacetic acid ester and rate constants of hydrolysis $k_1$, $k_{-1)$, $k_2$ were calculated.

• Bulletin of the Korean Chemical Society
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• v.28 no.11
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• pp.1958-1962
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• 2007

The title complex, Ir(H)(CO)(PEt3)2(η 2-C60) (2), has been prepared by the reaction of excess C60 (4 equiv) with a tetrairidium complex Ir4(CO)8(PEt3)4 (1) in refluxing chlorobenzene in 40% yield as green crystals. Compound 2 has been characterized by cyclic voltammetry (CV), spectroscopic methods (mass, IR, 1H and 31P NMR), and a single crystal X-ray diffraction study. The molecular structure reveals that the iridium atom of 2 is coordinated by two axial ligands of a hydrogen atom and a carbonyl group, and three equatorial ligands of two phosphorus atoms and an η 2-C60 moiety. The CV study exhibits three reversible one-electron redox waves for the successive reductions of 2, together with additional four redox waves due to free C60 reductions, which was formed by decomposition of 2 in the reduced states. The three reversible redox waves of 2 are shifted to more negative potentials by ca. 270 mV compared to free C60, reflecting both metal-to-C60 π-back-donation and the electron-donating nature of the two phosphorus ligands.

• Journal of the Korean Society of Food Culture
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• v.24 no.1
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• pp.77-83
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• 2009

This study was conducted to investigate the chemical composition and biological function of tea made from mountain-cultivated ginseng leaves. The antioxidant activities of tea made from mountain-cultivated ginseng leaves were determined by measuring their electron-donating ability based on their DPPH and nitrite-scavenging ability. The electron-donating abilities of tea made from mountain-cultivated ginseng leaves (500 and 1,000 ppm) as determined by DPPH assay were 45.6 and 85.1%, respectively. The nitrite scavenging ability of tea made from mountain-cultivated ginseng leaves (500 and 1,000 ppm) at pH 6.0 were 32.8 and 51.4%, respectively. Furthermore, the nitrite scavenging activity increased in a dose-dependent manner at all pH values. The effects of tea made from mountain-cultivated ginseng leaves on Male Sprague-Dawley rats were also evaluated. To accomplish this, the rats were divided into three groups (A: normal diet group, B: high fat diet group and C: high fat diet supplemented with tea made from mountain-cultivated ginseng leaves group). The anti-obesity effects of tea made from mountain-cultivated ginseng leaves were then evaluated. The serum total lipid, total cholesterol and triglyceride contents in C group were lower than those of B group; however, these differences were not statistically significant. The HDL-cholesterol content was significantly higher in the C group than in the other groups. Taken together the results of this study suggest that tea made from mountain-cultivated ginseng leaves possesses antioxidant activity and improves lipid metabolism.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.6
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• pp.796-804
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• 2010

This study was conducted to compare and analyze the qualitative property of MLT (mulberry leaf tea) and FMLT (fermented mulberry leaf tea) based on the antioxidant, anticancer activities of various extracts. When the antioxidant activity of MLT and FMLT extracts was evaluated, the electron donating activity was found to increase proportionally as the concentration of each extract increased. In addition, the extract of FMLT showed a higher electron donating activity than that of MLT. Furthermore, the ethanol extracts showed the highest electron donating ability. When the SOD activity was evaluated, it was also found to increase proportionally with the concentration of each extract. Furthermore, the SOD activity of the ethanol extract group was the highest, whereas the SOD like activities of both MLT and FMLT were similar. When nitrite decomposition was evaluated for each pH, the highest value was observed at pH 1.2. Finally, the nitrite deleting ability was the highest for the ethanol extracts. When each extract of MLT and FMLT was analyzed in vitro for anticancer effects, they were found to decrease the number of cancer cells proportionally as the concentration of extract increased for both HeLa cells and MCF-7 cells. Furthermore, FMLT was found to exert a greater inhibition of cancer cells than MLT. Among the extract groups, the ethanol extract induced the greatest inhibition of the development of cancer cells, and these effects were greater against MCF-7 cells than HeLa cells.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.3
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• pp.291-297
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• 2007

This study was conducted to investigate the hepatic detoxification effect of microcluster-water (McW). Animal experiments were divided into 4 groups: distilled water intake group (DC), distilled water intake-bromobenzene treated group (DB), McW intake group (MC), and McW intake-bromobenzene treated group (MB). There were no significant differences in alanine aminotransferase and aspartate aminotransferase activities between DC and MC groups, but the activities in MB group were significantly (p<0.05) lower than those in DB group. No apparent changes of aniline hydrolase activity were shown in all experimental groups, while glutathione S-transferase activity in MC and MB groups was higher than that in DC and DB, respectively. The content of hepatic lipid peroxide in DC group was similar to that of MC group. In addition, the contents in DB and MB groups were significantly (p<0.05) increased than that of DC group. The increasing rate in MB group was lower than that of DB group. Also, the electron donating activity of McW was significantly (p<0.05) higher than that of distilled water. From these results, it could be suggested that McW has the possibility of having detoxification effect of bromobenzene induced hepatic injury by increasing glutathione S-transferase, which is known as a kind of hepatiic detoxification enzyme.

• Journal of the Korean Chemical Society
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• v.24 no.1
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• pp.80-85
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• 1980

The free radical copolymeriaztion of N-vinylurea(VU) with vinyl acetate (VAc) was carried out at $60^{\circ}C$ in three solvents. VU-vinyl alcohol(VA) copolymers were prepared by the methanolysis of the VU-VAc copolymers. From the nitrogen content measurements of VU-VA copolymers, the monomer reactivity ratios for the VU-VAc copolymerization and the values of Alfrey-Price's Q and e for VU were determined. These Q and $\varrho$ values obtained in the cases of using methanol and methanol-dioxane as the polymerization solvents are comparable with those found for other monomers which have > NCO-pendent groups. The $\varrho$ value indicates that the urea group of VU is a electron-donating group. The copolymerization parameter of VU shows a strong effect of the solvents. These results are interpreted to be that VU is in equilibrium with its tautomer at the polymerization temperature.