• Journal of Microbiology and Biotechnology
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• 제19권7호
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• pp.734-741
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• 2009

Recently, strains of methicillin-resistant Staphylococcus aureus (MRSA) with reduced susceptibility to vancomycin (VCM) have been clinically isolated. The antibacterial activity of a new drug, linezolid (LZD), in such a strain was evaluated by measuring bacterial metabolic activity. A total of 73 MRSA strains having various susceptibilities to VCM were subjected to a novel and highly sensitive chemiluminescence-based assay. LZD MIC in the tested strains, measured by the microbroth dilution method, was within the range 1-4 mg/l (mostly ${\leq}2$mg/l), except for one LZD-resistant strain (NRS127; MIC=7 mg/l), and showed no correlation with VCM resistance. The chemiluminescence assay demonstrated that bacterial metabolic activity was strongly suppressed with increasing LZD concentration. The chemiluminescence intensity curve had a low baseline activity without tailing in most strains. The present results suggest that LZD has strong antibacterial activity against MRSA strains, and would be effective for treatment of infections that are poorly responsive to VCM. The chemiluminescence assay facilitated sensitive and discriminative susceptibility testing within a relatively short time.

• Natural Product Sciences
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• 제23권1호
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• pp.46-52
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• 2017

The aim of this study was to evaluate the anti-Helicobacter pylori activity of fractions and major aglycon compounds (baicalein, chrysin, oroxylin A, wogonin) of Scutellariae Radix. Minimum inhibitory concentration (MIC) measurement, DPPH radical-scavenging assay, DNA protection assay, and urease inhibition analysis were performed. The ethyl acetate (EtOAc) fraction showed the potent anti-Helicobacter activity, and therefore, compounds in the EtOAc fraction were subjected to further assay. The MICs of chrysin, oroxylin A, and wogonin against Helicobacter pylori 26695 were 6.25, 12.5 and $25{\mu}g/mL$, respectively. Baicalein exhibited the most effective DPPH radical-scavenging activity. DNA protection using Fenton reaction, chrysin, oroxylin A, and wogonin showed effective DNA protective effect. This result was also confirmed by quantitative real-time polymerase chain reaction (qRT-PCR). Regarding Jack bean urease (0.5 mg/mL, 50 unit/mg) inhibition, 20 mM ofbaicalein and chrysin inhibited urease activity by 88.2% and 72.5%, respectively.

• Journal of Microbiology
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• 제38권4호
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• pp.255-259
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• 2000

For rapid and sensitive measurement of antiviral activities, application of a recombinant virus containing firefly luciferase gene was attempted. Recombinant human cytomegalovirus (HCMV) containing luciferase gene driven by HCMV late gene pp28 promoter (HCMV/pp28-luc) was used to test the antiviral activities of three known compounds and the result was compared with results from the conventional plaque assay for measuring the production of infectious viruses. When human fibroblast cells were infected with HCMV/pp28-luc, luciferase activity was observed at 2 days after infection and reached maximum at 6 days after infection, whereas the production of infectious virus was maximal at 4 days after infection. The antiviral activities of ganciclovir, acyclovir, and papaverine were measured in HFF cells infected with HCMV/PP28-luc and the luciferase activity was compared with the infectious virus titers. Luciferase activity decreased as the concentration of ganciclovir or papaverine increased, while there was a slight decrease in luciferase activity with acyclovir. The level of the decrease in Luciferase activity was comparable to the level of decrease in the production of infectious virus. Therefore, the antiviral assay using recombinant virus HCMV/pp28-luc resulted in sensitivity similar to the conventional plaque assay with a significant reduction in assay time.

• Natural Product Sciences
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• 제9권4호
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• pp.299-303
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• 2003

For the screening of inhibitors of sterol biosynthesis from natural products, a simple and rapid assay method was developed using recombinant yeast carrying human lanosterol synthase, main target of this assay method. Sterol biosynthesis inhibition activity was monitored only by the inhibition of growth of the recombinant yeast. By changing the substrate, this assay method can figure out which step is inhibited in the sterol biosynthesis by the test material. With this assay method total 102 plant samples were screened for their inhibitory activity of sterol biosynthesis. Among plant water extracts screened, 11 plant samples showed inhibitory activity on sterol biosynthesis in ergosterol (-) medium. For selection of the specific inhibitory materials, 11 plant samples were reassayed in ergosterol (+) medium. After all 5 plant samples, Abutilon avicennae Gaertn. (stem), Alnus japonica Steud. (stem), Amaranthus mangostanus L. (aerial part), Philadelphus schrenckii Pupr. (leaf) and Pimpinelia brachycarpa Nakai (aerial part), showed specific inhibitory activity.

• The Plant Pathology Journal
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• 제32권4호
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• pp.363-370
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• 2016

Pseudomonas syringae pv. actinidiae (Psa) causes bacterial canker disease in kiwifruit. Antibacterial activity of plant essential oils (PEOs) originating from 49 plant species were tested against Psa by a vapor diffusion and a liquid culture assays. The five PEOs from Pimenta racemosa, P. dioica, Melaleuca linariifolia, M. cajuputii, and Cinnamomum cassia efficiently inhibited Psa growth by either assays. Among their major components, estragole, eugenol, and methyl eugenol showed significant antibacterial activity by only the liquid culture assay, while cinnamaldehyde exhibited antibacterial activity by both assays. The minimum inhibitory concentrations (MICs) of estragole and cinnamaldehyde by the liquid culture assay were 1,250 and 2,500 ppm, respectively. The MIC of cinnamaldehyde by the vapor diffusion assay was 5,000 ppm. Based on the formation of clear zones or the decrease of optical density caused by these compounds, they might kill the bacterial cells and this feature might be useful for managing the bacterial canker disease in kiwifruit.

• 생약학회지
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• 제50권2호
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• pp.112-117
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• 2019

In this study, extracts of bark from Ulmus davidiana var. japonica and its fractions were investigated the antioxidative, antibacterial and tyrosinase inhibition activity for physiological activity towards functional applications. In the measurement of DPPH radical scavenging activity, the ethyl acetate fraction showed higher radical scavenging ability than others. Moreover, in the tyrosinase inhibition assay, showed that the ethyl acetate fraction has good inhibition effects. Results of the DPPH radical scavenging and tyrosinase inhibition activity are related with the total polyphenol concentrations of ethyl acetate fraction. In antibacterial activity used to find out by utilizing the disc diffusion assay, chloroform fraction showed strong effect against Staphylococcus aureus and S. epidermidis. These results are related with the flavonoid contents of chloroform fraction. On the other hand, in the L929 cell viability measurement by MTT assay, the hexane, butanol and aqueous fraction treated at high concentration were showed cytotoxicity. But the others samples were exhibited a moderate viabilities. As a result of investigated the antioxidant and tyrosinase inhibition activity, the ethyl acetate fraction could be applicable for cosmetics related fields. And the chloroform fraction showed significant antibacterial activity against S. aureus and S. epidermidis.

• 한국식품과학회지
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• 제32권4호
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• pp.964-969
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• 2000

랩 등 PVC 제품의 가소제인 DEHA의 에스트로겐 활성을 검색하기 위하여 내분비계 장애작용 중 에스트로겐성 작용을 검색하는 대표적인 방법인 in vitro E-screen assay와 OECD 및 미국 EPA EDSTAC에서 권고하고 있는 in vivo 난소절제 랫드를 이용한 자궁 비대반응시험(uterotrophic assay)을 실시하였다. 시험결과 $DEHA(5{\times}10^{-9}{\sim}5{\times}10^{-4}\;M)$는 MCF-7세포의 증식을 유발하지 않았고 난소절제 랫드에 200 mg/kg/day 용량까지 투여하여도 자궁 및 질 무게에 영향을 미치지 않았다. 따라서 본 실험결과 DEHA는 E-screen assay 및 자궁비대반응시험에서 에스트로겐성 작용이 없는 것으로 확인되었으나, 이들 물질의 에스트로겐성에 대한 결론을 내리기 위해서는 여러 종류의 in vitro 시험 data 및 in vivo 시험 data가 더 보충되어야 할 것으로 생각된다.

• 한국약용작물학회지
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• 제7권1호
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• pp.37-44
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• 1999

60종(種)의 약용식물과 식용작물을 대상으로 항종양활성등의 생리활성을 조사함으로서 약용식물과 식용작물의 유용적인 측면의 확인뿐만 아니라 나아가서 새로운 생리활성물질 탐색의 가능성을 검토하기 위해서 실험하였으며 결과는 다음과 같다. 약용식물 및 식용작물에 대한 80% EtOH 추출물을 이용하여 항종양효과를 보면 PKC법에서는 명아주(73.4%) 및 antibleb형성억제력검정에서는 검정콩이, PLC법에서는 검정콩(91.9%), MTT법에서 50%의 억제력을 나타내는 농도$(IC_{50})$가 검정콩과 쑥의 경우 각각 $4.7{\mu}g/ml$을 보였다.

• Preventive Nutrition and Food Science
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• 제19권4호
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• pp.291-298
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• 2014

The aim of this study was to investigate the antioxidant activity of orange (Citrus auranthium) flesh (OF) and peel (OP) extracted with acetone, ethanol, and methanol. Antioxidant potential was examined by measuring total phenolic content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (RSA), total radical-trapping antioxidant potential (TRAP), oxygen radical absorbance capacity (ORAC), and cellular antioxidant activity (CAA). The comet assay was used to determine the protective effects of OF and OP against $H_2O_2$-induced DNA damage. TPC was highest in the acetone extracts of OF and OP. DPPH RSA was also higher in the acetone extracts than in the ethanol extracts. The DPPH RSA was highest in the acetone extracts of OF. The TRAP and ORAC values of the all extracts increased in a dose-dependent manner. In the TRAP assay, the acetone extracts of OF and OP had the lowest $IC_{50}$ values. In the CAA assay, the methanol and acetone extracts of OP had the lowest $IC_{50}$ values. All of the samples protected against $H_2O_2$-induced DNA damage in human leukocytes, as measured by the comet assay, but the acetone extracts of OP had the strongest effect. These results suggest that acetone is the best solvent for the extraction of antioxidant compounds from OF and OP. Furthermore, the high antioxidant activity of OP, which is a by-product of orange processing, suggests that it can be used in nutraceutical and functional foods.

• 한국축산식품학회지
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• 제40권2호
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• pp.297-310
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• 2020

This study aims to evaluate the probiotic properties of Lactobacillus brevis (L. brevis) KU200019 and the synergistic activity with prebiotics on antimicrobial activity, and the potential application as an adjunct culture in fermented dairy products. The commercial strain, L. brevis ATCC 14869 was used as reference strain. L. brevis KU200019 was showed higher viability in simulated gastric (99.38±0.21%) and bile (115.10±0.13%) conditions compared to reference strain. L. brevis KU200019 exhibited antimicrobial activity against various foodborne pathogens. The supplementation of fructooligosaccharides (FOS) enhanced viability of lactic acid bacteria (>8 Log CFU/mL) and antioxidant activity [2,2-diphenyl-2-picrylhydrazyl radical assay (DPPH) assay, 31.23±1.14%; 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assay, 38.82±1.46%] in fermented skim milk during refrigerated storage. L. brevis KU200019 was distinguished from the reference strain by its higher probiotic potential, antimicrobial activity, and higher antioxidant activity in fermented milk. Therefore, L. brevis KU200019 with FOS was demonstrated promising properties for further application in fermented dairy products with enhanced safety and quality.