• The Journal of the Korean Society for Microbiology
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• v.21 no.3
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• pp.375-380
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• 1986

Thirty-one strains of Pseudomonas aeruginosa were submitted to the synergistic activity test of amikacin(AK) and gentamicin(GM) combined with moxalactam(MX), ceftizoxime(CTZ) or cefoperazone(CFZ). The minimal inhibitory concentrations(MICs) of each drug and drugs combined in various ratios were measured by checkerboard dilution method. The synergism was determined through analysing the MIC distribution curve on isobologram and calculating the fractional inhibitory concentration index(FICI). MICs of GM, AK, MX, CFZ and CTZ against the 31 tested strains were distributed from $12.5{\mu}g/ml$ to $800{\mu}g/ml$, from $0.8{\mu}g/ml$ to $25{\mu}g/ml$, from $3.1{\mu}g/ml$ to $50{\mu}g/ml$, from $3.1{\mu}g/ml$ to $400{\mu}g/ml$, and from $12.5{\mu}g/ml$ to $100{\mu}g/ml$, respectively. The rate synergism of each drug combination by means of FICl was 45.5% in GM-MX, 36.4% in GM-CFZ, 63.6% in GM-CTZ, 48.6% in AK-MX, 35.3% in AK-CFZ, and 35.7% in AK-CTZ combination. Thus, it is suggested that Pseudomonas aeruginosa may effectively be inhibited by various aminoglycoside and cephalosporin combinations.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.3
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• pp.188-192
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• 2008

Methyl gallate isolated from bark of the tree Rhus verniciflua Stokes has significant antimicrobial activity against the fish pathogenic bacteria Edwardsiella tarda and Vibrio anguillarum. To evaluate the antimicrobial activity of gallate derivatives, eight alkyl gallates were tested. Ethyl gallate and propyl gallate had the highest activities, with MICs of $15.6-31.3{\mu}g/mL$ against E. tarda. For V. anguillarum, propyl gallate and butyl gallate were highly effective, with MICs of $7.81-31.3{\mu}g/mL$. When used in combination with antibiotics, methyl gallate exhibited synergistic effects with oxytetracycline against E. tarda and with norfloxacin against V. anguillarum. These results suggest that short-chain alkyl gallates can be used as alternatives to antibiotics against the fish pathogenic bacteria.

• Korean Journal of Plant Resources
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• v.29 no.6
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• pp.699-703
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• 2016

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious clinical and an urgent problem worldwide. Few new drugs are available against MRSA, because MRSA has the ability to acquire resistance to most antibiotics, which consequently increases the cost of medication. In the present study, the antibacterial activity of Hydnocarpi Semen was investigated. The most effective method is to develop antibiotics from the natural products without having any toxic or side effects. Therefore, there is a need to develop alternative antibacterial drugs for the treatment of infectious diseases. Five Clinical isolates (MRSA) were obtained from five different patients at Wonkwang University Hospital (Iksan, South Korea). The Other 2 strains were ATCC 33591 (Methicillin-resistant strain) and ATCC 25923 (Methicillin-susceptible strain). Antibacterial activity (Minimal Inhibitory Concentrations, MICs) was determined by broth dilution method, disk diffusion method, MTT test, and checkerboard dilution test. Antibacterial activity of n-hexane fraction was remarkable, and had a MICs ranging from $31.25-125{\mu}g/m{\ell}$. FICI values for HFH+AM and HFH+OX were 0.13-0.19 and 0.04-0.29, showing the increase of synergistic effect. When combined together, these antibacterial effects were dramatically increased.

• International Journal of Oral Biology
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• v.41 no.4
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• pp.209-215
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• 2016

Chlorhexidine has long been used in mouth washes for the control of dental caries, gingivitis and dental plaque. Minimal inhibitory concentration (MIC) is the lowest concentration of an antimicrobial substance to inhibit the growth of bacteria. Concentrations lower than the MIC are called sub minimal inhibitory concentrations (sub-MICs). Many studies have reported that sub-MICs of antimicrobial substances can affect the virulence of bacteria. The aim of this study was to investigate the effect of sub-MIC chlorhexidine on biofilm formation and coaggregation of oral early colonizers, such as Streptococcus gordonii, Actinomyces naeslundii and Actinomyces odontolyticus. The biofilm formation of S. gordonii, A. naeslundii and A. odontolyticus was not affected by sub-MIC chlorhexidine. However, the biofilm formation of S. mutans increased after incubation with sub-MIC chlorhexidine. In addition, cell surface hydrophobicity of S. mutans treated with sub-MIC of chlorhexidine, decreased when compared with the group not treated with chlorhexidine. However, significant differences were seen with other bacteria. Coaggregation of A. naeslundii with A. odontolyticus reduced by sub-MIC chlorhexidine, whereas the coaggreagation of A. naeslundii with S. gordonii remained unaffected. These results indicate that sub-MIC chlorhexidine could influence the binding properties, such as biofilm formation, hydrophobicity and coaggregation, in early colonizing streptococci and actinomycetes.

• Korean journal of food and cookery science
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• v.27 no.1
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• pp.1-9
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• 2011

Anti oralmicrobial effects of Nulembo nucifera were determined against S.mutans, S.sobrinus S.sobrinus, F.nucleatum, and A.actinomycetemcomitans using paper disc method, minimum inhibitory concentrate (MICs). Extracts of lotus leaf showed the highest yield. MeOH extract is 21%, Chloroform fraction is 4.2%, ethylacetate fraction is 8.2%, water fraction is 19%. Different parts such as flower, leaf, seed and pod showed antimicrobial effects against S.mutans, with flower and seed extracts showing strong antimicrobial effect aganinst S.sobrinus KCCM11897. Leaf extract(1000pm concentration) showed over 50% inhibitory effect against S.mutans and S.sobrinus KCCM11897. Flower extract showed over 40% inhibitory effect against F.nucleatum and A.actinomycetemcomitans. MICs of flower extract against S.sobrinus KCCM11897,11898 and leaf extract against S.mutans, S.sobrinus KCCM11897 were $625\;{\mu}g/ml$, indicating Nulembo nucifera extract can exert antimicrobial activity even at low concentration. All extractes with heat at $120^{\circ}C$ had antimicrobial activity, which means that is a very stable substances. F.nucleatum and A.actinomycetemcomitans was stable against acid it had a trend that the more akali side was the lower acitivity.

• Korean Journal of Veterinary Service
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• v.42 no.4
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• pp.301-304
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• 2019

The objective of this study was to determine the in vitro intracellular and extracellular minimum inhibitory concentrations (MICs) of 13 antimicrobials against one recently isolate Lawsonia intracellularis, the etiological agent of proliferative enteropathy (PE). The final MICs were assessed by counting the number of heavily infected cells (HICs;>30 bacteria per cell) using an immunoperoxidase monolayer assay. Enrofloxacin (InMIC; 1~2 ㎍/mL and ExMIC; 16 ㎍/mL) still presented the most notable antimicrobial susceptibility, and marbofloxacin (2 ㎍/mL and 8 ㎍/mL) was followed. Colistin (0.25 ㎍/mL and 2 ㎍/mL) presented a susceptibility followed by tylvalosin (1 ㎍/mL and 2 ㎍/mL). Florfenicol and lincomycin had the weakest susceptibility and amoxicillin, penicillin G, chlortetracycline, oxytetracycline, tiamulin, tilmicosin, and tylosin displayed weak susceptibility. Although some antibiotics showed decreased susceptibility patterns, they showed similar patterns to recent antibiotic susceptibility patterns in Korea. In addition, these results could be one of contributions in clinical fields.

• International Journal of Oral Biology
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• v.33 no.4
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• pp.213-216
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• 2008

Continentalic acid (CA, (-)-pimara-8(14), 15-diene-19-oic acid) was isolated from the roots of Aralia cordata (Araliaceae) using bioassay-guided fractionation of a crude chloroform extract. The antibacterial activity of CA against Enterococcus faecalis and Enterococcus gallinarium was estimated by determining minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). CA exhibited potent activity against standard vancomycin-resistant enterococci (VRE) and vancomycin-susceptible enterococci (VSE), with MICs and MBCs values between 4 and $8{\mu}g/mL$ and 4 and $16{\mu}g/mL$, respectively. This compound exhibited potent activity against strains of VRE, which are highly resistant to clinically useful antibiotics. These findings suggest that continentalic acid may be useful in controlling enterococcal infection.

• ALGAE
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• v.24 no.3
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• pp.179-184
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• 2009

Methanol crude extract of the sea grass Zostera marina L. and organic solvent fractions (n-hexane, chloroform, ethyl acetate, n-butanol, and water) were screened for antioxidant activity (total phenolic contents, DPPH scavenging activity, and reducing power) and antimicrobial activity against three human skin pathogens, two bacteria and a yeast; Staphylococcus aureus, Staphylococcus epidermidis, and Candida albicans. Total phenolic contents and 2, 2- diphenyl-1-picrylhydrazyl (DPPH) scavenging activity were highest in the ethyl acetate fraction with 968.50 $\mu$g gallic acid equivalent per milligram of extract, and ca. 95% scavenging activity on the DPPH radicals at 10 mg $ml^{-1}$. In antimicrobial activity tests, MICs (Minimum Inhibitory Concentration) of each Zostera marina extract partitioned ranged from 1mg to 8 mg $ml^{-1}$ (extract/ 10% DMSO) against all three human skin pathogens. The MICs of the ethyl acetate and n-butanol fractions were the same with 1 mg $ml^{-1}$ against S. aureus and C. albicans. The ethyl acetate fraction of Z. marina does protect against free radicals and may be used to inhibit the growth of human skin pathogens.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.89-95
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• 1998

The aim of this study is to elucidate the anti-microbial activity and anti-oxidative activity of water-soluble chitosan with a molecular weight of 5,000-200,000. Water-soluble chitosans have demonstrated a regular anti-microbial activity on the tested strians by the paper disk method. In the MIC (Minimum Inhibitory Concentration) test, CC-01 (MW=5,000) with the lower MW showed the higher MIC value than the higher MW chitosan. The MW of chitosan increase, the MIC decreases. MICs of 4 chitosans(CC-02∼CC-05) against S. aureusTCC 65389, E coli ATCC 8739, p. aeruginosa, ATCC 9027 and C. albicans ,ATCC 10231 were 7.0-39.O$\mu\textrm{m}$, whereas MICs of chitosans against A. niger were over 2.OmM. Formula containing chitosan showed higher anti-microbial activities than the formula made with the chemical preservatives(Methylparaben 0.2％ and Imidazolidinyl Urea 0.3％). Among 5 water-soluble chitosans, CC-03(MW=92,163) showed the most potent anti-oxidative activity (IC$\sub$50/ : 0.2mM). In conclusion, the water-soluble low molecular weight chitosan could be served as natural preservatives and antioxidant in cosmetics.

• Mycobiology
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• v.35 no.1
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• pp.39-43
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• 2007

The antifungal effect of pine needle extract prepared by a distinguishable extraction method and the dry distillation method, was examined. The effect of this extract itself was insignificant. The chemical components of pine needle extract were then investigated by gas chromatographic analysis, and four, chemical components, acetol, furfural, 5-methyl furfural, and terpine4-ol, were identified. The antifungal effects of those four chemical components against Alternaria mali (A. mali), an agent of Alternaria blotch of apple, were then examined. It was observed that the minimum inhibitory concentrations (MICs) were 6.25, 0.78, 0.78, and 12.5 (mg/ml) of acetol, furfural, 5-methyl furfural, and terpine-4-ol, respectively. MICs of furfural and 5-methyl furfural had the same order of magnitude as that of an antifungal agrochemical, chlorothalonil. Although furfural itself can not be completely substituted for an antifungal agrochemical, a partial mixture of furfural and antifungal agrochemical may be used as a substitute. The use of agrochemicals for the prevention of plant disease caused by pathogenic fungus such as A. mali could be partially reduced by the application of this mixture.