• Natural Product Sciences
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• v.7 no.1
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• pp.1-4
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• 2001

The antioxidant activity of Pinus densiflora was determined by measuring the radical scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The methanol extract of P. densiflora showed strong antioxidant activity, and thus fractionated with several solvents. The antioxidant activity potential of the individual fraction was in the order of ethyl acetate>n-butanol>water>dichloromethane> n-hexane fraction. The ethyl acetate soluble fraction exhibiting strong antioxidant activity was further purified by repeated silica gel column chromatography. Antioxidant (+)-catechin was isolated as one of the active principles from the ethyl acetate fraction, together with the inactive components, dihydrokaempferol and 1-O-benzoylglucose. The radical scavenging effect of (+)-catechin on DPPH radical exceeded to that of L-ascorbic acid which is a well known antioxidant.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.260-263
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• 2006

In this study, we investigated the antimicrobial effect of 14 different herbal petal extracts on various foodborne and food spoilage bacteria. Herbal petal extracts were prepared with 70% ethanol followed by sequential hexane, chloroform, ethyl acetate, n-butanol, and water fractionation. Antimicrobial activity was highest in the ethanol fraction from roselle (Hibiscus sabdariffa L.) petals as determined by the paper disc method. The roselle ethanol extract retarded the growth of food spoilage bacteria in kimbap (rice rolled in dried laver). Foodborne microorganisms (e.g. Bacillus cereus and Clostridium perfringens), on the other hand, were most efficiently inhibited by the ethyl acetate fraction of the roselle petal extract as determined by growth inhibition curves. Our study shows that roselle petals harbor antimicrobial activity against foodborne and food spoilage microorganisms. The critical ingredient is highly enriched in the ethyl acetate fraction of the extract.

• Natural Product Sciences
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• v.7 no.3
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• pp.72-75
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• 2001

The antioxidant activity of roasted defatted perilla (Perilla frutescens) seed was determined by measuring its radical scavenging effect on 1,1-diphenyl-2- picrylhydrazyl (DPPH) radicals, inhibitory activity on total reactive oxygen species generation in kidney homogenates using 2',7'-dichlorodihydro-fluorescein diacetate, and scavenging effect on authentic peroxynitrites. The methanolic extract of roasted defatted perilla seed showed strong scavenging activity in both DPPH and peroxynitrite radicals, and thus fractionated with several solvents. The antioxidant activity potential of the individual fraction was in the order of ethyl acetate>n-butanol>dichloromethane>water>n-hexane fraction. The ethyl acetate soluble fraction exhibiting strong antioxidant activity was further purified by repeated silica gel and Sephadex LH-20 column chromatography. Luteolin was isolated as one of the active principles from the ethyl acetate fraction, together with the inactive chrysoeriol and apigenin.

• Bulletin of the Korean Chemical Society
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• v.23 no.10
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• pp.1409-1412
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• 2002

Polymeric membrane electrodes for acetate anion based on meso-(${\alpha}$,${\alpha}$,${\alpha}$,${\alpha}$)-5,10,15,20-tetrakis[2-(penta-fluorophenylurea) phenyl]porphyrin I and similar urea-functionalized porphyrins Ⅱ-Ⅳ as neutral ionophores were prepared. The membrane based on porphyrin I exhibits the best potentiometric properties in pH 6.0 rather than pH 7.0: linear stable response over a wide concentration range (6.0 ${\times}$$10^{-5}$-1.0 ${\times}$$10^{-2}$) with a slope of -59.6 mV/decade and a detection limit of log[CH3CO$O^-$] = -5.32. Selectivity coefficients obtained from the matched potential method (MPM) in pH 6.0 indicate that interferences of hydrophobic anions are very small for the membranes of porphyrins I and II having the strong withdrawing group. The electronic effect of urea-functionalized porphyrins and pH effect of buffer solutions are discussed on the potentiometric response.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.42-47
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• 2019

The four different polymer compounds were manufactured to make cable sheath for ship industry. Two kinds of ethylene-vinyl acetate (EVA) were selected as main matrix polymers for compounding with fire retardant, crosslinking agent, filler, plasticizer, and other additives. The properties of the four compounded materials were investigated with the contents of fire retardant, silane coated aluminum hydroxide (S-ATH). Rheology, Mooney viscosity, and tensile strength increased with S-ATH contents by reinforcing effect. With increasing fire retardant amount, fire resistance increased, but cold resistance didn't show an obvious enhancement due to polar effect of vinyl acetate in EVA.

• The Korea Journal of Herbology
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• v.24 no.1
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• pp.23-33
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• 2009

Objectives : The present study was performed to clarify the antioxidant and anticancer effects of extract of stamens of Nelumbo nucifera and Kaempferol. Methods : Antioxidant effect was measured by DPPH-radical scavenging activity for electron donating ability (EDA), superoxide dismutase (SOD)-like activity for SOD and lipid peroxidation. Anticancer effect was assessed by MTT absorbance for cytotoxicity. Results : Vitamin E, Kaempferol and ethyl acetate extract of stamens of Nelumbo nucifera increased SOD-like activity and DPPH-radical scavenging activity dose-dependently. On the contrary, lipid peroxidation was time-dependently decreased. Furthermore, Kaempferol and ethyl acetate extract of stamens of Nelumbo nucifera significantly decreased the growth rate of C6 glioma cells. Conclusions : These results suggest that ethyl acetate extract of stamens of Nelumbo nucifera may be a putative antioxidant or anticancer substance.

• Journal of Life Science
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• v.23 no.3
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• pp.383-388
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• 2013

This study was performed to determine the whitening effect of several solvent fractions of Diospyros kaki extracts. Fractions from ethanol extracts of D. kaki were prepared by a systematic fractionation procedure using hexane, ethyl acetate, butanol, and $H_2O$. The ethyl acetate fractions were used to evaluate the inhibitory effects on tyrosinase activity and melanin synthesis in B16F10 melanoma cells. Ethyl acetate fractions suppressed the expression of tyrosinase, TRP-1 and TRP-2 in B16F10 melanoma cells. These results showed that ethyl acetate fractions of D. kaki could be developed as a skin whitening material in cosmetics.

• Journal of the Korean Chemical Society
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• v.14 no.3
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• pp.207-212
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• 1970

A large variety of weed killers, insecticides, and bactericiedes on the market today are of almost infinite variety, but their pharmacological effects are different from each other according to the objects to cope with. Therefore, it is hoped that some chemical substance which serves as weed killer, an insecticide, and a bactericede at a same time, should be synthesized, in order to save expense and labor. I anticipated that the desire would be met by introducing to a molecule the radical which has the three effects. Here, I made an attempt of introducing $Cl_2$ gas to aniline considering the following respects: 1. Introduction velocity of $Cl_2$ gas under the varied temeratures and velocities of $Cl_2$ gas 2. The effect of reaction period under the condition which gives the most satisfactory yield. 3. The actions of catalysts, $SbCl_3$, $FeCl_3$, and $MoCl_5$, and their proportions when a mixture of the three catalysts is used in producing 2,6-dichloro-aniline. After consideration of above phenomena, the maximum production rate of 79.5% of 2.6-compound was obtained. With the compound I synthesized 2.6-dichloro-4-nitroaniline-mercuric acetate. Investigations of the effects of the compound as weed killer, an insecticide, and a bactericide showed that the compound, 2,6-dichloro-4-Nitro Aniline mercuric acetate has a satisfactory herbi-insecti-bactericidal effect.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1251-1255
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• 2003

Second-order rate constants have been determined spectrophotometrically for the reaction of phenyl 4-nitrophenyl carbonate with a series of primary amines in $H_2O$ containing 20 mol % DMSO at 25.0 ${\circ}$C. The Bronsted-type plot is linear with a ${\beta}_{nuc}\;0.69 {\pm} 0.04$, which is slightly smaller than the ${\beta}_{nuc}$ values for the reactions of 4-nitrophenyl acetate ( $\beta_{nuc}= 0.82 {\pm} 0.03$) and benzoate ( $\beta_{nuc} = 0.76 {\pm} 0.01$), indicating that the reaction proceeds through a tetrahedral zwitterionic intermediate $T^{\pm}$. The carbonate is more reactive than the corresponding acetate and benzoate. The changing Me (or Ph) to PhO has resulted in a decrease in the ${\beta}_{nuc}$ value without changing the reaction mechanism but an increase in the reactivity. The electronic effect of the substituent in the nonleaving group appears to be responsible for the enhanced reactivity of the carbonate compared with the corresponding acetate and benzoate.

• Journal of Adhesion and Interface
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• v.12 no.1
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• pp.1-10
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• 2011

An automated reaction calorimeter was used to directly monitor the rate of emulsion polymerization of vinyl acetate using poly(vinyl alcohol) (PVAs) having different degrees of blockiness. By using this technique in conjunction with other off-line measurements of the evolution of particle size distributions, important details of the process were observed. No constant graft rate period was observed for both low and high initial monomer-water ratios. The gel effect was observed for the low monomer-water ratio recipe. The particle size distributions were broad (particle diameter 40~100 nm) and bimodal. Continuous nucleation was observed to be accompanied by 'limited aggregation' and flocculation during the particle growth stages. It was speculated to be due to the occurrence of the extensive 'limited aggregation' and chain transfer to PVA leading to grafting.