• Fisheries and Aquatic Sciences
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• 제18권1호
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• pp.1-6
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• 2015

In an effort to discover alternative antimicrobials against Listeria monocytogenes, several marine algae were screened. The methanolic extract of Ecklonia cava exhibited the highest antibacterial activity against L. monocytogenes, with the ethyl acetate (EtOAc) soluble fraction of E. cava methanolic extract having a MIC value of $256{\mu}g/mL$ and a MBC value of ${\mu}g/mL$. The MIC values of streptomycin in combination with the EtOAc fraction were markedly reduced up to 64-fold, suggesting that the antibacterial activity of the antibiotic was restored when combined with the EtOAc fraction. The interaction between streptomycin and the EtOAc fraction was assessed by fractional inhibitory concentration (FIC) indices. The combination of streptomycin and the EtOAc fraction against L. monocytogenes resulted in ${\Sigma}FIC_{min}$ range of 0.141 to 0.266 and ${\Sigma}FIC_{max}$ of 0.531 for all strains. The median ${\Sigma}FIC$ against L. monocytogenes strains ranged from 0.172 to 0.344. Thus, synergistic ranges of FIC <1 were observed for all combinations of streptomycin and the EtOAc fraction against L. monocytogenes strains. Indeed, the median ${\Sigma}FIC$ of streptomycin-EtOAc fraction ranged from 0.172 to 0.344, suggesting a marked synergy.

• 한국미생물·생명공학회지
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• 제38권4호
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• pp.405-413
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• 2010

무화과는 뽕나무 과에 속하며 세계에서 가장 오래된 과일 중 하나이고, 국내에서는 주로 소화장애, 염증성궤양 그리고 가려움증 등에 사용되어 왔다. 본 연구에서는 무화과 잎을 메탄올로 추출한 후 임상진료실에서 분리된 메티실린 내성 황색포도상구균(MRSA)에 대한 항균활성을 보았다. 그 결과 분리된 MRSA 1-20에서 최소억제농도 (MIC)는 2.5 mg/mL에서 20 mg/mL 농도로 측정되었으며, 최소살균농도(MBC)는 5 mg/mL에서 20 mg/mL 농도로 관찰되었다. Oxacillin이나 ampicillin과 병용투여 시 4-8배 이상의 MIC/MBC농도가 감소되었으며, FICI 값도 0.0375-0.5이하로 병용효과를 나타내었다. 더불어 메탄올추출물 단독 사용시 보다 항생제와 병용투여 시 빠른 사멸효과를 보였다. 결론적으로 무화과 잎이 메티실린 내성 황색포도상구균에 항균활성을 나타냄을 확인하였으며, 메티실린 내성 황색포도상구균 감염에 천연 치료제로서의 가능성을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제17권5호
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• pp.858-864
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• 2007

This study investigated the antibacterial activities of sophoraflavanone G from Sophora flavescens in combination with two antimicrobial agents against oral bacteria. The combined effect of sophoraflavanone G and the antimicrobial agents was evaluated using the checkerboard method to obtain a fractional inhibitory concentration(FIC) index. The sophoraflavanone G+ampicillin(AM) combination was found to have a synergistic effect against S. mutans, S. sanguinis, S. sobrinus, S. gordonii, A. actinomycetemcomitans, F nucleatum, P. intermedia, and P. gingivalis, whereas the sophoraflavanone G+gentamicin(GM) combination had a synergistic effect against S. sanguinis, S. criceti, S. anginosus, A. actinomycetemcomitans, F nucleatum, P. intermedia, and P. gingivalis. Neither combination exhibited any antagonistic interactions(FIC index>4). In particular, the MICs/MBCs for all the bacteria were reduced to one-half$\sim$one-sixteenth as a result of the drug combinations. A synergistic interaction was also confirmed by time-kill studies for nine bacteria where the checkerboard suggested synergy. Thus, a strong bactericidal effect was exerted through the drug combinations, plus in vitro data suggested that sophoraflavanone G combined with other antibiotics may be microbiologically beneficial rather than antagonistic.

• Journal of Microbiology and Biotechnology
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• 제26권4호
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• pp.784-789
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• 2016

We evaluated the synergistic antibacterial effect in combination with the chitosan-ferulic acid conjugate (CFA) and β-lactam antibiotics, such as ampicillin, penicillin, and oxacillin, against methicillin-resistant Staphylococcus aureus (MRSA) using fractional inhibitory concentration (FIC) indices. CFA clearly reversed the antibacterial activity of ampicillin, penicillin, and oxacillin against MRSA in the combination mode. Among these antibiotics, the combination of oxacillin-CFA resulted in a ΣFIC_min range of 0.250 and ΣFIC_max of 0.563, suggesting that the oxacillin-CFA combination resulted in an antibacterial synergy effect against MRSA. In addition, we determined that CFA inhibited the mRNA expression of gene mecA and the production of PBP2a, which is a key determinant for β-lactam antibiotic resistance, in a dose-dependent manner. Thus, the results obtained in this study supported the idea on the antibacterial action mechanism that oxacillin will restore the antibacterial activity against MRSA through the suppression of PBP2a production by CFA.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2294-2298
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• 2009

In present work an attempt was made to synthesize various analogues of levofloxacin by introducing new functionality at carboxylic group position via nucleophilic substitution reaction. For this purpose the carboxylic group at C-6 was esterified and later subjected to nucleophilic attack at the carbonyl carbon by various aromatic amines. Structure of the analogues was confirmed by different techniques i.e. IR, $^1H$ NMR and mass spectrometry. The antibacterial activity of the derivatives was also assessed and compared with the parent against a series of Gram-positive and Gramnegative bacteria. A synergistic as well as antagonistic behavior was observed in these derivatives. Additionally unlike levofloxacin, the derivatives were also found to modulate oxidative burst response of phagocytes exhibiting moderate to significant inhibitory activity.

• ALGAE
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• 제29권1호
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• pp.47-55
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• 2014

To develop effective and safe acne vulgaris therapies with a continuing demand for new solutions, we investigated unique efficacy of an antibacterial agent from marine brown alga Eisenia bicyclis in treating acne vulgaris. The methanolic extract of E. bicyclis exhibited potential antibacterial activity against acne-related bacteria. The ethyl acetate fraction showed the strongest antibacterial activity against the bacteria among solvent fractions. Six compounds (1-6), previously isolated from the ethyl acetate fraction of E. bicyclis, were evaluated for antibacterial activity against acne-related bacteria. Among them, compound 2 (fucofuroeckol-A [FF]) exhibited the highest antibacterial activity against acne-related bacteria with a minimum inhibitory concentration (MIC) ranging from 32 to $128{\mu}g\;mL^{-1}$. Furthermore, FF clearly reversed the high-level erythromycin and lincomycin resistance of Propionibacterium acnes. The MIC values of erythromycin against P. acnes were dramatically reduced from 2,048 to $1.0{\mu}g\;mL^{-1}$ in combination with MIC of FF ($64{\mu}g\;mL^{-1}$). The fractional inhibitory concentration indices of erythromycin and lincomycin were measured from 0.500 to 0.751 in combination with 32 or $64{\mu}g\;mL^{-1}$ of FF against all tested P. acnes strains, suggesting that FF-erythromycin and FF-lincomycin combinations exert a weak synergistic effect against P. acnes. The results of this study suggest that the compounds derived from E. bicyclis can be a potential source of natural antibacterial agents and a pharmaceutical component against acnerelated bacteria.

• Journal of Microbiology and Biotechnology
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• 제31권9호
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• pp.1288-1294
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• 2021

There are a growing number of reports of hospital-acquired infections caused by pathogenic bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA). Many plant products are now being used as a natural means of exploring antimicrobial agents against different types of human pathogenic bacteria. In this research, we sought to isolate and identify an active molecule from Sedum takesimense that has possible antibacterial activity against various clinical isolates of MRSA. NMR analysis revealed that the structure of the HPLC-purified compound was 1,2,4,6-tetra-O-galloyl-glucose. The minimum inhibitory concentration (MIC) of different extract fractions against numerous pathogenic bacteria was determined, and the actively purified compound has potent antibacterial activity against multidrug-resistant pathogenic bacteria, i.e., MRSA and its clinical isolates. In addition, the combination of the active compound and β-lactam antibiotics (e.g., oxacillin) demonstrated synergistic action against MRSA, with a fractional inhibitory concentration (FIC) index of 0.281. The current research revealed an alternative approach to combating pathogenesis caused by multi-drug resistant bacteria using plant materials. Furthermore, using a combination approach in which the active plant-derived compound is combined with antibiotics has proved to be a successful way of destroying pathogens synergistically.

• Fisheries and Aquatic Sciences
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• 제18권3호
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• pp.241-247
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• 2015

In an effort to discover alternative phytotherapeutic antimicrobial agents to combat Streptococcus parauberis, a fish pathogenic bacterium, we evaluated the antibacterial activity of seaweed extracts in vitro. A methanolic extract of Ecklonia cava exhibited strong antibacterial activity against S. parauberis isolated from olive flounder Paralichthys olivaceus. Furthermore, the n-hexane soluble (Hexane) fraction of the E. cava methanolic extract exhibited the greatest antibacterial effect on S. parauberis strains with a minimum inhibitory concentration (MIC) ranging from 256 to $1,024{\mu}g/mL$. In addition, the MIC values of oxytetracycline against antibiotic-resistant S. parauberis were markedly reduced up to 64-fold in combination with the Hexane fraction, suggesting that the antibacterial activity of the antibiotic was restored when combined with the Hexane fraction. The interaction between both antibiotics and the Hexane fraction was assessed by the fractional inhibitory concentration (FIC) index. The Hexane fraction and oxytetracycline combination against antibiotic-resistant S. parauberis strains resulted in a median ${\sum}FIC$ range of 0.502 to 0.516. Thus, the synergistic ranges of median ${\sum}FIC$ < 1 were observed for all combinations of the Hexane fraction and oxytetracycline against S. parauberis. To the best of our knowledge, this is the first report indicating the efficacy of an E. cava extract against fish pathogenic bacterium S. parauberis.

• Natural Product Sciences
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• 제20권1호
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• pp.39-43
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• 2014

Papenfussiella kuromo (PK) is a marine plant and an abundant ecological resource for the future; it is found in almost 80% of the terrestrial biosphere. The aim of this study was to investigate the antibacterial activity of PK against methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant pathogen. The minimum inhibitory concentrations (MICs) of PK hexane fraction (PKH) against 7 strains of MRSA ranged from 1.0 to 2.0 mg/mL. In the checkerboard dilution method, a synergistic effect of the PKH and the antibiotics (oxacillin and norfloxacin) was seen. PKH markedly reduced the MIC of each of the 4 antibiotics against MRSA. The time-kill assay showed that the synergistic activity of PKH and an antibiotic reduced the bacterial counts below the lowest detectable limit after 24 h. These findings suggest that PKH has antibacterial activity, and may be important baseline data in future extensive studies of living marine resources as a source of compounds active against MRSA.

• 한국미생물·생명공학회지
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• 제38권3호
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• pp.289-294
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• 2010

단삼(Salvia miltiorrhiza Bunge)은 우리나라에서 전통적으로 부종, 관절염, 간염 등과 같은 염증질환의 치료에 사용해왔다. 본 연구에서는 단삼 메탄올 추출물을 이용하여 구강미생물에 대한 항균활성을 확인하였다. 그 결과 메탄올추출물은 실험 되어진 모든 구강미생물에서 강한 항균활성을 나타내었다(MICs, 8 to $64\;{\mu}g/mL$; MBCs, 16 to $64\;{\mu}g/mL$). 추가적으로 ampicillin이나 gentamicin과의 병용투여서 최소억제농도(MIC)와 최소살균농도(MBC)가 감소하는 병용효과를 나타내었다. 더불어 메탄올추출물 단독 사용시 보다 항생제와 병용투여시 빠른 사멸효과를 보였다. 결론적으로 단삼 메탄올추출물이 치아우식을 유발하는 많은 세균들에 대한 항균효과가 뛰어남을 확인 할 수 있었으며, 안정성이 높은 천연 치아우식예방제로서의 개발가능성을 확인하였다.