• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.3
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• pp.704-709
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• 2009

The emergence of methicillin-resistant of Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) has led to an urgent need for the discovery and development of new antibacterial agents. As part of an ongoing investigation into the antibacterial properties of the natural products, (2S)-7,4'-dihydroxy-5-methoxy-8-(${\gamma}$, ${\gamma}$-dimethylally)-f1avanone (2S-DMDF), isolated from the roots of Sophora flavescens, was found to be antibacterial active MRSA and VRE. Sophora flavescens has been used as antibacterial, antiviral, antiprotozoal, anti-inflammatory. Therefore, this study investigated the antibacterial activity of 2S-DMDF against all the bacterial strains tested. In this result, at the end point of an optically clear well, the minimum inhibitory concentrations (MICs) ranged from 0.97 to 15.6 mg/ml for 2S-DMDF, from 125 to 256 mg/ml for ampicillin, and from 64 to 512 mg/ml for gentamicin with MRSA, also, 7.8 to 15.6 mg/ml for 2S-DMDF, from 125 to 256 mg/ml for ampicillin, and from 512 to 1024< mg/ml for vacomicin with VRE. These findings indicated that the application of the tested 2S-DMDF alone might prove useful in the control and treatment of MRSA and VRE infections.

• Natural Product Sciences
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• v.20 no.1
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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.

• Journal of Life Science
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• v.21 no.4
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• pp.589-595
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• 2011

This work focused on screening and characterizing antibiotic-producing actinomycetes to develop new antibiotics that can overcome the growing resistance of disease-causing microbes. One-hundred actinomycetes strains were isolated from soil samples from Chungcheongbuk-do, Korea using various kinds of actinomycetes isolation media, including a starch casein agar medium and potato dextrose agar (PDA). Among them, strain BCNU 1030 was determined to show strong antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA). Biochemical, physiological, and 16S rRNA sequence analyses indicated that strain BCNU 1030 belonged to the genus Streptomyces. Strain BCNU 1030 exhibited antibiotic activity against a wide range of bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA). The minimum inhibitory concentration (MIC) of BCNU 1030 dichloromethane extract was determined to be $0.78\;{\mu}g/ml$ for MRSA CCARM 3090. Therefore, Streptomyces sp. BCNU 1030 has potential for anti-MRSA drug development.

• Journal of Life Science
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• v.29 no.1
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• pp.84-89
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• 2019

Previous screening of novel antibacterial agents revealed that some bacterial isolates exhibited antibiotic activity against both gram-positive and gram-negative bacteria and that they showed antibacterial activity, even against methicillin-resistant Staphylococcus aureus (MRSA). Among these isolates, one bacterial strain, BCNU 1204, was identified as Pseudomonas aeruginosa using phenetic and phylogenetic analysis, based on 16S ribosomal RNA gene sequences. The maximum productivities of antimicrobial substances of BCNU 1204 were obtained after being cultured at $35^{\circ}C$ and pH 7.0 for 4 d in King's medium B (KMB). Dichloromethane (DCM) and ethylacetate (EA) extracts of P. aeruginosa BCNU 1204 exhibited strong antimicrobial activity, particularly against gram-positive bacteria. The EA extracts exhibited broad-spectrum activity against antibiotic resistant strains. Fraction 5-2, was obtained by recycling preparative liquid chromatography (LC) and preparative thin-layer chromatography (TLC) and was identified as phenazine-1-carboxylic acid belonging to phenazines using gas chromatography and mass spectrometry (GC/MS). Its minimum inhibitory concentration (MIC) values were $25{\mu}g/ml$, $50{\mu}g/ml$, ${\geq}25{\mu}g/ml$, and ${\geq}50{\mu}g/ml$ for MRSA CCARM 3089, 3090, 3091, and 3095 strains, respectively. P. aeruginosa BCNU 1204 may be a potential resource for the development of anti-MRSA antibiotics. Additional research is required to identify the active substance from P. aeruginosa BCNU 1204.

• Korean Journal of Pharmacognosy
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• v.54 no.2
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• pp.72-79
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• 2023

MRSA is Staphylococcus aureus resistant to β-lactam antibiotics, and is a worldwide infectious disease. Even with the discovery of new antibiotics, resistance develops rapidly, so new alternatives are needed. Jakyakgamcho-tang (JGT) is a combination of Jakyak and Gamcho, and has been mainly used as an antispasmodic and analgesic in oriental medicine. This study was conducted to find out whether there is an effect on MRSA in relation to the anti-inflammatory effect of JGT and the antibacterial effect of Jakyak and Gamcho found in previous studies. In this study, in order to investigate the antibacterial activity of JGT and the combined effect of existing antibiotics, after extracting JGT with 70% EtoH, the disc diffusion method, minimum inhibitory concentration (MIC), drug combination effect (FICI), and time-kill analysis (Time-kill assay), metabolic inhibition, Western blot and qRT-PCR analysis were used to confirm the antibacterial activity mechanism of MRSA of JGT. As a result of the experiment, all of MRSA showed antibacterial activity in JGT's disc diffusion method, and the MIC was 250-1000 ㎍/mL. When existing antibiotics and JGT were combined with drugs, most had synergy or partial synergy. In addition, it was confirmed that the degree of bacterial growth was suppressed over time when simultaneous administration for 24 hours. JGT showed a synergistic effect when administered together with the ATPase-inhibitor DCCD, suggesting that it affected the inhibition of ATPase. As a result of observing the expression of PBP2a, and hla protein in the JGT-treated group and the untreated control group through wstern blot, it was confirmed that the protein expression of the JGT-treated group was significantly suppressed, and the expression levels of mecA, mecR1 and hla genes were also suppressed during JGT treatment. was observed by qRT-PCR. Combining the results of the experiment, it can be seen that JGT has antibacterial activity in MRSA, and when combined with existing antibiotics, the effect was increased compared to treatment with the drug alone. This suggests that JGT can be an alternative to treatment for antibiotic resistance of MRSA.

• Bulletin of the Korean Chemical Society
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• v.35 no.9
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• pp.2818-2824
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• 2014

Trp residue is considered as one of the important constituents in antimicrobial peptides (AMPs) as it presence secured good activities in many cases. However, it is preferable to be changed because of their sensitivity towards light. We have synthesized the short Trp-rich AMP Pac-525 and its analogues to investigate the possibility of His(chx) as possible replacement analogue for Trp in AMPs. Based on the assay result of the antibacterial activity including anti-MRSA activity, His(chx) is considered as good candidate for the Trp replacement. Through these study, we found that His(chx) had several merits to design therapeutic antimicrobial agents compare to Trp in terms of i) increasing antibacterial activity without hemolytic activity, ii) successful in designing the short peptide (only four residues), iii) having anti-MRSA activity, iv) overcoming the light sensitivity. Furthermore, transmission electron microscopy (TEM) and dye leakage experiments suggested that P11 and P16 containing His(chx) kill bacteria via forming pore/ion channels on bacterial cell membranes.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.3
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• pp.285-295
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• 2016

To investigate the effect of dietary fiber from mozuku, Cladosiphon novae-caledoniae kylin (C. novae-caledoniae kylin) on the skin care, we measured anti-oxidant activity, anti-microbial activities, tyrosinase activity inhibition and elastic activity. B16F10 melanoma cell (MTT assay) were used to measure cell viability. MC and MI exhibited in vitro antibacterial activity against Staphyloccus aureus (S. aureus) and MRSA without antifungal activity. Mozuku extract (MS) showed excellent tyrosinase inhibition effect compared to arbutin as a positive control (to 49% for tyrosine). The wrinkle-improving effect was relatively low. However, wrinkle-improving effect was relatively low. DPPH free radical scavenging activity was 89% in a concentrations at $500{\mu}g/mL$. These results indicate that the mozuku extracts may be an effective cosmetic ingredient for skin whitening.

• Journal of Microbiology and Biotechnology
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• v.24 no.1
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• pp.44-47
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• 2014

A biotransformation approach using microbes as biocatalysts can be an efficient tool for the targeted modification of existing antibiotic chemical scaffolds to create previously uncharacterized therapeutic agents. By employing a recombinant Streptomyces venezuelae strain as a microbial catalyst, a reduced macrolide, 10,11-dihydrorosamicin, was created from rosamicin macrolide. Its chemical structure was spectroscopically elucidated, and the new rosamicin analog showed 2-4-fold higher antibacterial activity against two strains of methicillin-resistant Staphylococcus aureus compared with its parent rosamicin. This kind of biocatalytic approach is able to expand existing antibiotic entities and can also provide more diverse therapeutic resources.

• Journal of Life Science
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• v.29 no.2
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• pp.223-230
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• 2019

Ozone is a gaseous molecule able to kill microorganisms, such as yeast, fungi, bacteria, and protozoa. However, ozone gas is unstable and cannot be used easily. In order to utilize ozone properly and efficiently, plant oil can be employed. Ozone reacts with C-C double bonds of fatty acids, converting to ozonized oil. In this reaction, ozonide is produced within fatty acids and the resulting ozonized oil has various biological functions. In this study, we showed that ozonized oil has antimicrobial activity against fungi and bacteria. To test the antimicrobial activity of ozonized oil, we produced ozonized olive oil. Ozonized olive oil was applied to Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. Antimicrobial activity was assayed using the disk diffusion method following the National Committee for Clinical Laboratory Standards. Minimal inhibitory concentrations (MIC) were 0.25 mg for S. aureus, 0.5 mg for S. epidermidis, 3.0 mg for P. aeruginosa, and 1.0 mg for E. coli. Gram positive bacteria were more susceptible than Gram negative bacteria. We compared growth inhibition zones against S. aureus and MRSA, showing that the ozonized olive oil was more effective on MRSA than S. aureus. Furthermore, the ozonized olive oil killed C. albicans within an hour. These data suggested that ozonized olive oil could be an alternative drug for MRSA infection and could be utilized as a potent antimicrobial and antifungal substance.

• Korean Journal of Clinical Laboratory Science
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• v.47 no.3
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• pp.140-146
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• 2015

The increase in resistance by pathogenic bacteria to multiple antimicrobial agents has become a significant treat, as the effective antimicrobial agents available for the patients infected by such resistant bacteria are reduced, or even eliminated. Several natural plant extracts have exhibited antibacterial and synergistic activity against various resistant microorganisms. Houttuynia cordata is frequently used by many traditional medicine practicioners for its antimicrobial, antiviral, and anti-inflammatory properties. This study investigated the antibacterial effects of H. cordata extract against clinical multi-resistant bacteria, and compared the two methods used for the antimicrobial susceptibility testing. Thirty isolates of Methicillin-resistant Staphylococcus aureus (MRSA, 10), Vancomycin-resistant Enterococcus faecium (VRE, 10), Carbapenem-resistant Acinetobacter baumannii (CRAB, 10) were included in this study. The antibacterial effect of H. cordata was tested by disk diffusion and microbroth dilution methods as per CLSI guidelines. In disk diffusion, all isolates (30) showed no inhibition to 30,000 ug/mL of H. cordata. But in the microbroth dilution method, $MIC_{90}$ of H. cordata was 4,096 ug/mL, 8,192 ug/mL and 4,096 ug/mL in MRSA, VRE and CRAB, respectively. These results demonstrate that H. cordata exhibits antibacterial activity against MRSA, VRE and CRAB. Moreover, the microbroth dilution method is a more effective method than disk diffusion to evaluate the antibacterial activity of natural products. The Disk diffusion method used to evaluate the antibacterial activity of natural products required new standard guidelines including inoculum concentration of bacteria.