• Journal of Pharmacopuncture
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• v.25 no.1
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• pp.37-45
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• 2022

Objectives: The quorum-sensing-inhibitory and anti-biofilm activities of the methanol extract of E. globulus leaves were determined against clinically isolated multidrug-resistant Pseudomonas aeruginosa. Methods: The preliminary anti-quorum-sensing (AQS) activity of eucalyptus was investigated against a biosensor strain Chromobacterium violaceum ATCC 12472 (CV12472) by using the agar well diffusion method. The effect of sub-minimum inhibitory concentrations (sub-MICs) of the methanol extract of eucalyptus on different quorum-sensing-regulated virulence factors, such as swarming motility, pyocyanin pigment, exopolysaccharide (EPS), and biofilm formation, against clinical isolates (CIs 2, 3, and 4) and reference PA01 of Pseudomonas aeruginosa were determined using the swarm diameter (mm)-measurement method, chloroform extraction method, phenol (5%)-sulphuric acid (concentrated) method, and the microtiter plate assay respectively, and the inhibition (%) in formation were calculated. Results: The preliminary AQS activity (violacein pigment inhibition) of eucalyptus was confirmed against Chromobacterium violaceum ATCC 12472 (CV12472). The eucalyptus extract also showed concentration-dependent inhibition (%) of swarming motility, pyocyanin pigment, EPS, and biofilm formation in different CIs and PA01 of P. aeruginosa. Conclusion: Our results revealed the effectiveness of the E. globulus extract for the regulation of quorum-sensing-dependent virulence factors and biofilm formation at a reduced dose (sub-MICs) and suggest that E. globulus may be a therapeutic agent for curing and controlling bacterial infection and thereby reducing the possibility of resistance development in pathogenic strains.

• The Journal of Internal Korean Medicine
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• v.34 no.3
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• pp.278-288
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• 2013

Objectives : Methicillin-resistant Staphylococcus aureus (MRSA) has a cephalosporin and beta-lactam antibiotic-resistant strains. MRSA is one of the major pathogens causing hospital infection and the isolation ratio of MRSA has gradually increased. Consequently, increased resistance to antibiotics is causing serious problems in the world. Therefore, there is a need to develop alternative antimicrobial drugs for the treatment of infectious diseases. Methods : The antibacterial activities of Ipyo-san were evaluated against 2 strains of MRSA and 1 standard Methicillin-susceptible staphylococcus aureus (MSSA) strain by using the disc diffusion method, minimal inhibitory concentrations (MIC) assay, colorimetric assay using MTT test, checkerboard dilution test and time-kill assay performed under dark. Results : The MIC of Ipyo-san water extract against S. aureus strains ranged from 1000 to $2,000{\mu}g/ml$, so we confirmed that it had a strong antibacterial effect. Also, the combinations of Ipyo-san water extract and conventional antibiotics exhibited improved inhibition of MRSA with synergy effect. We suggest that Ipyo-san water extract against MRSA has antibacterial activity so it has potential as alternatives to antibiotic agents. For the combination test, we used Triton X-100 (TX) and DCCD for measurement of membrane permeability and inhibitor of ATPase. As a result, antimicrobial activity of Ipyo-san water extract was affected by the cell membrane. Conclusions : We suggest that the Ipyo-san water extract lead the treatment of bacterial infection to solve the resistance and remaining side-effect problems that are the major weak points of traditional antibiotics.

• Archives of Pharmacal Research
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• v.23 no.1
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• pp.46-49
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• 2000

Two neolignan compound, magnolol $(5,5^{l}-diallyl-2,2^{l}-dihydroxybiphenyl, 1)$ and honokiol $(5,5^{l}-diallyl-2,4^{l}-dihydroxybiphenyl, 2)$ were isolated from the stem bark of Magnolia obovata and evaluated for antifungal activity against various human pathogenic fungi. Compound 1 and 2 showed significant inhibitory activities against Trichophyton mentagrophytes, Microsporium gypseum, Epidermophyton floccosum, Aspergillus niger, Cryptococcus neoformans, and Candida albicans with minimum inhibitory concentrations (MIC) in a range of $25-100{\mu}g/ml$. Therefore, compound 1 and 2 could be used as lead compounds for the development of novel antifungal agents.

• Journal of the Korean Applied Science and Technology
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• v.37 no.1
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• pp.145-152
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• 2020

In this study, the antimicrobial activity was tested by Ethanol extract(ET), Ethyl acetate fraction(EA) and Butanol fraction(BT) of Rhus javanica L fruit as natural preservatives. The antimicrobial activity were tested by Paper disc method and minimum inhibitory concentration (MIC) for microorganisms (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, Candida Albicans). As a result of the antimicrobial activities of P. aeruginosa fruit extracts have shown the clear zone that S. aureus, S. epidermidis, E. coli, and P. aeruginosa. In BT, additional clear zones were observed for the Candida. The MIC results showed that EA samples showed the lowest concentrations for S. aureus S. epidermidis, E. coli, and P. aeruginosa. Accordingly, it can be concluded that these Rhus javanica L fruit extracts have the potential for antimicrobial materials for the cosmetic industry.

• International Journal of Oral Biology
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• v.40 no.1
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• pp.41-50
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• 2015

The aim of this study was to identify bacteria isolated from the oral cavities and to determine their antimicrobial susceptibility against eight antibiotics. The bacterial strains were obtained from the Korean Collection for Oral Microbiology (KCOM). The bacteria were identified by comparing 16S rDNA sequences at the species level. The data showed that 77 bacterial strains were predominantly identified as streptococci (49.4%) and staphylococci (14.3%). Minimum inhibitory concentrations (MIC) were determined using a broth dilution assay to test the sensitivity of the bacterial strains. The MIC values of the oral bacterial strains against antibiotics were different. Streptococci were sensitive to clindamycin, cefuroxime axetil, and vancomycin, and they were resistant to tetracycline. Staphylococci also were sensitive to clindamycin, cefuroxime axetil, and vancomycin, and they were resistant to penicillin antibiotics. Gramnegative bacterial strains were sensitive to tetracycline and were resistant to clindamycin. These results suggest that the antimicrobial susceptibility test is necessary in deciding the prescription for antibiotics, to prevent the misuse or abuse of antibiotics.

• International Journal of Oral Biology
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• v.33 no.4
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• pp.197-203
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• 2008

It has been reported that the antimicrobial susceptibility patterns of viridans streptococci vary according to geographical region. Although several studies on the antibiotic resistance of viridans streptococci in foreign countries have been reported, little is known about the distribution of resistance among viridans streptococci in Korea. In this study, 88 isolates of viridans streptococci from Korean students' dental plaque were identified as 12 different species. The susceptibility of these isolates to 8 antibiotics was investigated. The in vitro antibiotic activity of penicillin G, ampicillin, vancomycin, streptomycin, gentamicin, erythromycin, amoxicillin, and tetracycline was measured by the broth microdilution method. The range of the minimum inhibitory concentrations (MIC), MIC50, MIC90, and the percentage of the susceptible isolates were determined. Streptococcus mutans and Streptococcus salivarius were susceptible to the 8 antibiotics. Isolates with resistance to vancomycin, streptomycin, and amoxicillin were not found. The overall resistance rates of the 88 isolates to penicillin G, ampicillin, gentamicin, erythromycin, and tetracycline were 12.5%, 62.5%, 62.5%, 26.1%, and 26.1%, respectively.

• Microbiology and Biotechnology Letters
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• v.13 no.4
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• pp.339-344
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• 1985

Cephalosporin C(CPC) inhibited the growth of Cephalosporium acremonium M-113, a potent CPC producer derived from C acremonium ATCC 20339. Similar inhibitory effects of CPC were also observed in growth of C. acremonium ATCC 20339 and ATCC 14553. Minimum inhibitory concentrations (MIC) of CPC on the growth of conidia and hyphae of C. acremonium M-113 were 200-500 and 3000-4000$\mu\textrm{g}$/$m\ell$ respectively in synthetic medium. MIC values were increased in complex media. The inhibitory effect of CPC was due to CPC-exerted inhibition of amino acids uptake by the cells. 3'-Group of CPC might be important in its inhibitory action. In audition, CPC itself could be utilized by the cells as a nitrogen source under nitrogen limited condition.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2003.10b
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• pp.44-44
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• 2003

Leaves from natural populations of Artemisia princeps var. orientalis in Suncheon of South Korea were examined for antimicrobial and antioxidative activities monthly (April through October). The antimicrobial activity of the ethyl acetate and water fractions of crude methanol extract from the plant collected monthly against three gram-positive, two gram-negative and one lactic acid bacteria were studied. The ethyl acetate and water fractions of crude methanol extract from A. princeps var. orientalis collected in August and September had the highest antimicrobial activity. Minimum inhibitory concentrations (MIC) for each strain by ethyl acetate fraction of methanol extract from A. princeps var. orientalis was different depending on strains and sampling months. MIC for each strain was the highest in the sample of April, followed by October. In specific, MIC for Bacillus cereus was around 0.25mg/disc in the sample of April. The MIC for Staphyllococcus aureus was 0.01mg/disc in the sample of July, August, and September. It was the lowest value among tested strains and samples. And the antimicrobial activity for Lactobacillus plantarum was not found at any concentrations and sampling months. The in vitro antioxidative activities of methanol extract from Artemisia princeps var. orientalis collected monthly were determined by the scavenging of DPPH radical and inhibition of xanthine oxidase activity. The DPPH scavenging activity of the extracts from the plant sampled in May, June and July were higher than any other months. The xanthine oxidase activity of the extract of A. princeps var. orientalis collected in April and May showed the greatest activity, it is different with antimicrobial activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1022-1028
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• 1999

The solvent extracts of Ulmi cortex, which were extracted by using several solvents with different polarities, were prepared for utility as a natural preservatives. The antimicrobial activities and cell growth inhibitions were investigated to each strain with the different concentrations of Ulmi cortex extracts. Methanol extract showed the highest antimicrobial activity. The methanol extract was represented the broad antimicrobial activities for the gram positive and negative strains. Minimum inhibitory concentrations (MIC) for each strains were appeared to around 0.3mg/ml at each of Bacillus cereus, Bacillus subtilis, and Staphylococcus aureus. The cell growth inhibitions were not shown on Lactobacillus bulgaricus, Lac tobacillus plantarum, and Bifidobacterium bifidum, but greatly on the Clostridium butyricum. The meth anol extracts were further reextracted sequentially with hexane, chloroform, ethyl acetate, and butanol for purifying crude methanol extracts. The extract, which was reextracted by butanol, showed the highest antimicrobial activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.6
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• pp.1008-1013
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• 1994

To develope naatural food preservatives, ethanol and water extracts were prepared from the leaf mustard (Brassica juncea Coss.) and antimicrobial activities were examined against 15 microorganisms which were food borne pathogens and/or food poisioning microorganisms and food-related bacteria and yeasts. Ethanol extract exhibited anitmicrobial activities for the microorganism tested, especially, minimum inhibitory concnetrations exhibited antimicrobial activities for the microorganism tested, especially, minimum inhibitory concentrations (MIC) for Bacillus subtilis and Bacillus natto were as low as 10mg/ml. MIC of water extract was 40-60mg/ml for bacteria and yeast. The ethanol extract showed the antimicrobial activity by 3~6 times higher than the water extract. Antimicrobial activity of the ethanol extract was not destroyed by the heating at $121^{\circ}C$ for 15 min and not affected by pH.