• KSBB Journal
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• v.14 no.5
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• pp.517-522
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• 1999

A green tea used in this experiment was cultivated at Bosung (Chonnam) and purchased from a domestic market. The extract at 5$0^{\circ}C$ water from the powder of green tea partitioned with chloroform and ethyl acetate. The resulting solution was further purified with a chromatographic column (4.6$\times$250 mm, 15${\mu}{\textrm}{m}$, Lichrospher 100RP-18). Finally separation was achieved on a $\mu$-Bondapak $C_18$(3.9$\times$300mm, 10${\mu}{\textrm}{m}$) column. The elution order of the catechin compounds contained in the green tea was EGC(Epigallocatechin, C(catechin), EC(Epicatechin), EGCG(Epigallocatechin Gallate) and ECG(Epicatechin Gallate). From the experimental results the mobile phase for isolating EGCG from the extract consisted of 0.1% acetic acid in water/acetonitrile, 87/13%(v/v). The flow rate of mobile phase was 1.0 $m\ell$/min, and UV wavelength was fixed at 280 nm. 121.3 mg of EGCG, higher than 98% of purity, was obtained from 5 g of dry green tea.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.9
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• pp.1419-1425
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• 2004

This study was performed to examine in vitro antioxidative activities such as DPPH radical scavenging activity, reducing power and tyrosinase inhibitory effect of various solvent fractions from Chionanthus retusa leaves. Ethyl acetate fraction showed potent antioxidative activity and tyrosinase inhibitory effect. The active compound was isolated from the butanol fraction by silica gel column chromatography and MPLC. The isolated compound was luteolin-4'-O-glucoside determined by $^1H$, $^{13}C$-NMR and 2D NMR. Compared with several antioxidant compounds, luteolin-4'-O-glucoside exhibited effective DPPH radical scavenging activity and reducing power in a concentration dependent manner. Bioassay with pure luteolin-4'-O-glucoside showed a dose-independent inhibitory effect on L-DOPA oxidation by mushroom tyrosinase and its $IC_{50}$ values were established as 23.2 ${\mu}g/mL$. Therefore, we may suggest that luteolin-4'-O-glucoside can be used as a food additive possessing the potent antioxidative activity and skin-whitening cosmetic material.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.843-848
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• 1996

Porous resin beads of Poly(styrene-co-divinylbenzene) have been prepared by suspension polymerization. The bead could be made porous in the region above 30wt% of the crosslinking agent(divinylbenzene ) and the porogenic agent(toluene), respectively. The specific surface area of porous beads increased with increasing the concentrations of divinylbenzene and toluene. The specific surface area of the porous resin bead decreased, when sulfonated with concentrated sulfuric acid. The catalytic activity of sulfonated resin catalyses increased with increasing the degree of crosslinking in the liquid-phase reesterification of ethyl acetate with 1-propanol. The adsorbed quantity of sodium dodecylbenzene sulfonate in an aqueous solution also increased with increasing surface area of porous resins.

• Korean Journal of Food Science and Technology
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• v.39 no.5
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• pp.564-568
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• 2007

In this study, the ethanolic extracts of 40 species of traditional herbal medicines were examined for their antimicrobial activities against Clostridium difficile. Among the 43 screened traditional herbal medicines, Achyranthes Japonica Nakai (AJN), Siegesbeckia glabrescens Makino, and Phelloedendron amurense Ruprecht showed antimicrobial activities greater than 90% at a concentration of 500 ppm. According to the minimum inhibitory concentration (MIC) test the ethyl acetate soluble fraction of the AJN ethanolic extracts (AJNEA) showed the highest growth inhibitory activity against C. difficile, with a MIC of $625{\mu}g/mL$. In addition, the effect of AJNEA on the growth of lactic acid bacteria was investigated. AJNEA did not inhibit the growth of the tested Bifidobacterium spp. or Lactobacillus spp., with the exception of B. longum, Streptococcus thermophilus, and L. helveticus. These results indicate that AJNEA can be utilized as a potential antimicrobial agent against C. difficile related disease.

• Korean Journal of Pharmacognosy
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• v.31 no.1
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• pp.51-56
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• 2000

This study was carried out to evaluate cytotoxic effects of the roots of Sophora flavescens Ait. extracts on murine leukemia tumor cells lines $(P388D_1\;and\;L1210)$. Disruptions in cell organelles were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The comparison of $IC_{50}$ values of the ethyl acetate of Sophora flavescens Ait. extract in leukemia cell lines showed that their susceptibility to these extracts decreased in the following order : Adriamycin>Fr.4>Fr.5>Fr.3>Fr.1>Fr.2 by the MTT assay. These results suggest that the fraction 4 of the ethyl acetate soluble extract of Sophora flavescens Ait. may be a valuable choice for the studies on the treatment of murine leukemia cell lines.

• The Korean Journal of Pesticide Science
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• v.12 no.3
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• pp.243-248
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• 2008

The present research was conducted to determine insecticidal activity of methanol extract and its fractions from the fig (Ficus carica L.) leaves grown under different cropping conditions, glasshouse, plastic house, and outdoor. Methanol extracts from fig loaves grown at outdoor showed higher insecticidal activity (80 to 89%) against Tetranychus urticae than those at plastic house or glass house. Especially ethylacetate and hexane fractions from methanol extracts of fig leaves grown at outdoor exhibited the highest insecticidal activity against Tetranychus urticae, showing 92% and 90% control, respectively. The results suggest that methanol extract and its fractions from outdoor-grown fig leaves had the potent insecticidal activity as a plant-based insect control mean.

• Microbiology and Biotechnology Letters
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• v.40 no.4
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• pp.333-338
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• 2012

Lichens are a symbiosis between fungi, algae and cyanobacteria. Our group recently studied the antioxidant properties of some bacterial species isolated from Arctic lichens and we confirmed that they possess high antioxidant activities. In this paper, we investigated the antioxidant capacity of 5 microorganisms newly isolated from 4 Arctic lichen species, Cladonia sp., Sterocaulon sp., Umbilicaria sp. and Cetraria sp., using various solvent extractions. We carried out 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2'-azino-bis(3-ethyl benzothiazoline-6-sulphonic acid) (ABTS) free radical scavenging activity test and ferric reducing antioxidant power (FRAP) assay. Also total phenolic and flavonoid content assays were performed. Among the bacterial culture extracts of the tested lichen-microorganisms, ethyl acetate extracts of Burkholderia sordidicola S5-B(T) had not only a high antioxidant activity (72.9%) when compared with the ascorbic acid used as the control (51.3%) in the DPPH assay, but also a high amount of phenolic content as well as flavonoid content. As a result, these lichen-microorganisms may be potentially useful sources of natural antioxidants.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.527-536
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• 2014

An ethanolic extract from Myagropsis yendoi was fractionated using several solvents. Among these, an ethyl acetate fraction (Myagropsis yendoi ethyl acetate fraction: MYE) showed the highest anti-inflammatory activity based on inhibition of lipopolysaccharides (LPS)-induced nitric oxide (NO) production in RAW 264.7 cells. We thus investigated the molecular mechanisms underlying MYE's inhibitory effects. Pretreatment of cells with up to $30{\mu}g/mL$ of MYE significantly inhibited NO production and inducible nitric oxide synthase expression in a dose-dependent manner (P<0.05). Similarly, MYE markedly reduced the production of pro-inflammatory cytokines, such as interleukin (IL)-$1{\beta}$, IL-6, and tumor necrosis factor (TNF)-${\alpha}$, as well as their mRNA levels. While the nuclear translocation of nuclear factor-kappa B (NF-${\kappa}B$) was strongly suppressed by MYE, the activation of a nuclear factor erythroid 2-related factor (Nrf2) was increased. Moreover, MYE significantly reduced the phosphorylation of JNK, p38 MAPK, and phosphatidylinositol 3-kinase/Akt in LPS-stimulated cells. These results indicate that MYE contains anti-inflammatory compounds, and that it might be used as a dietary supplement for the prevention of inflammatory diseases.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.4
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• pp.133-137
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• 2014

As a preceding process for preparing several micrometer sized Ag-coated Cu flakes, ball milling of submicrometer-sized Cu particles synthesized through a wet chemical method was performed in order to convert the particles into flakes. To suppress oxidation and aggregation of the particles during ball milling, ethylene glycol and ethyl acetate were used as a medium and a surface modifying agent, respectively. Results obtained with different rotation speeds of a jar indicated that the rotation speed changes a rotating mode, and strikingly alters the final shapes and shape uniformity of Cu particles after milling. The diameter of zirconia ball was also confirmed. Although there was aggregates in the initial submicrometer-sized Cu particles, therefore, well-dispersed Cu flakes with a size of several micrometers were successfully prepared by ball milling through optimization of rotation speed, amount of ethyl acetate, and diameter of zirconia ball.

• Journal of Forest and Environmental Science
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• v.22 no.1
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• pp.13-17
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• 2006

Approximately each 5 kg dried Paulownia coreana leaves, seeds, outer barks, inner barks and wood were ground, extracted with acetone-$H_2O$ (7:3. v/v). concentrated under reduced pressure and successively fractionated using n-hexane. $CH_2Cl_2$, EtOAc and $H_2O$ on a separation funnel. Each fraction was then freeze dried and weighed. The extraction yield of each sample was investigated and the yield of inner barks was the highest, while the wood was the lowest. Antioxidative activities of crude extracts, precipitates and partitioned fractions were evaluated by DPPH radical scavenging method. The results indicated that all EtOAc soluble fractions, including some of $H_2O$ soluble fractions, showed significantly high antioxidative potential compared with ${\alpha}$-tocopherol and BHT used as controls.