• Research in Plant Disease
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• v.23 no.2
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• pp.89-98
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• 2017

Ralstonia solanacearum species complex (RSSC) causes bacterial wilt, and it is one of the most important soil-borne plant pathogenic bacteria. RSSC has a large host range of more than 50 botanical families, which represent more than 200 plant species, including tomato. It is difficult to control bacterial wilt due to following reasons: the bacterial wilt pathogen can grow inside the plant tissue, and it can also survive in soil for a long period; moreover, it has a wide host range and biological diversity. In most previous studies, scientists have focused on developing biological control agents, such as antagonistic microorganisms and botanical materials. However, biocontrol attempts are not successful. Plant-derived metabolites and extracts have been promising candidates to environmentally friendly control bacterial wilt diseases. Therefore, we review the plant extracts, essential oils, and secondary metabolites that show potent in vivo antibacterial activities (in potted plants or in field) against tomato bacterial wilt, which is caused by RSSC.

• YAKHAK HOEJI
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• v.43 no.3
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• pp.342-350
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• 1999

The antibacterial activity against Propionibacterium acnes (P. acnes), $5{\alpha}-reductase$ inhibition and comedolytic effects are the important pharmacological target sites of antiacne drughs. We previously reported on the antibacterial activities against P. acnes by natural products. In the present study the screening of $5{\alpha}-reductase$ inhibition and comedolytic effects from natural products were performed. Seven natural products such as Angelica koreana, Sophora flavescens, Prunus persica, Bombyx mori, Areca catechu, Galla rhois and Gleditschia koraiensis perfectly inhibited the activity of $5{\alpha}-reductase$ at the concentration of 0.01% (w/v). Sixteen natural products which were shown to have the potent antibacterial activities against P.acnes or $5{\alpha}-reductase$ inhibition activities were assayed for the comedolytic test. In the results of comedolytic effects on experimentally-induced comedones (EIC), Sophora flavescens showed the strongest comedolytic effect on EIC, and Polygonum cuspidatum and Angelica koreana showed stronger comedolytic effects on EIC than azelaic acid used for a positive control at the concentration of 3% (w/v). These results suggest that several natural products including Sophora flavescens can be developed as noble antiacne agents.

• Journal of the Korean Chemical Society
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• v.38 no.7
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• pp.521-525
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• 1994

New cephalosporin antibiotics, 7-[(3,4-dihydro-6-methoxycarbonyl-2,2-dimethyl-2H-1,4-thiazin-3-yl)acetamido]-3-heterocyclothiomethyl-3-cephem-4-carboxylic acid derivatives(2a∼2d) were synthesized. Antibacterial activities of these new cephalosporin derivatives and the relationship between their structures and their activities were examined. Among them,7-[(3,4-dihydro-6-methoxycarbonyl-2,2-dimethyl-2H-1,4-thiazin-3-yl)acetamido]-3-[(2-methyl-1,3,4-thiadiazol-5-yl)thiomethyl]-3-cephem-4-carboxylic acid exhibited the broad antibacterial activities against Gram(+) and Gram(-) bacteria.

• Bulletin of the Korean Chemical Society
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• v.32 no.1
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• pp.229-238
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• 2011

A series of novel glucose derived benzyl and alkyl 1,2,3-triazoles and their hydrochlorides have been synthesized via Cu(I)-catalyzed 1,3-dipolar cycloaddition. All the new compounds were characterized by MS, IR and NMR spectra. The DEPT, APT, $^1H$-$^1H$ and $^1H-^{13}C$ 2D NMR spectra for some compounds were also recorded. These compounds were evaluated for their in vitro antibacterial activities against Staphylococcus aureus ATCC 29213, Bacillus subtilis, Bacillus proteus, Pseudomonas aeruginosa, Escherichia coli ATCC 25922, and antifungal activities against Candida albicans and Aspergillus fumigatus. The bioactive data revealed that (3R,4S,5S,6S)-2-(hydroxymethyl)-6-methoxy-4,5-bis((1-octyl-1H-1,2,3-triazol-4-yl)methoxy)-tetrahydro-2H-pyran-3-ol 8a exhibited excellent antifungal activity against A. fumigatus with an MIC value of 0.055 mM compared to Fluconazole. It also showed broad inhibitory efficacy against tested bacterial strains with MIC values ranging from 0.049 mM to 0.39 mM.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.538-548
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• 1995

Calcium hydroxide has been used not only as pulp capping and pulpotomy agents in the operative dentistry, but dressing and temporary filling materials in root canal treatment. Calcium hydroxide was known to stimulate odontoblast to produce new reparative dentin and to eliminate microorganims effectively in the infected root canals. The purpose of this study was to evaluate the effect of calcium hydroxide solution on cultured L929 cells and its antibacterial effect on several streptococci. Calcium hydroxide solution (0.121g/100ml) was added to L929 cells and cell viability was measured using 3-(4,5-dimethylthiazol-2-yl) -2,5-dimethyltetrazolium bromide (MTT) and neutral red (NR) dye. Calcium hydroxide solution (20, 40, 60, 80, 100 and $150{\mu}l$) was added to L929 cells in 96-well microplates for 1, 4 and 24 hours respectively. Cell viability was gradually decreased when the volume and exposure time of calcium hydroxide solution were increased. When $150{\mu}l$ of calcium hydroxide was applied to L929 cells for 24 hours, there was more than fifty percent reduction of cell viability. Calcium hydroxide solution (20g/100ml) showed antibacterial effect against S. uberis, S. intermedius and S. mitis after thirty-second exposure. But 0.121g/100ml concentration of cacium hydroxide solution exhibited no antibacterial effect on six streptococci after one-hour exposure.

• Journal of Microbiology and Biotechnology
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• v.31 no.9
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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.

• Journal of Korean Biological Nursing Science
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• v.23 no.1
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• pp.1-10
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• 2021

Purpose: To verify the anti-microbiotic activity and to develop eco-friendly surface disinfectants using the Opuntia ficus-indica extract. Methods: The stem and fruits of the Opuntia cultivated in Jeju Island were extracted with hot water, 70% EtOH and 100% MeOH, respectively. To examine the antimicrobial activity of the extracts, gram positive bacteria (Bacillus subtilis, Staphylococcus aureus), gram negative bacteria (Escherichia coli, Salmonella typhimurium), yeast (Candida albicans), mold (Aspergillus flavus) and antibiotic resistant bacteria (E. coli, S. aureus) were measured to form a clear zone. Results: The antibacterial activity of the fruit extract was higher than that of the stem extract, and the antibacterial activity of the 100% MeOH (FM) extract and the 70% EtOH (FE) extract of the palm cactus fruit was suitable for the surface disinfectant overall, and clear-zone formed even at relatively low concentrations (250 mg/mL). The FM and FE have antibacterial activity against various bacteria, therefore they can be used as disinfectants. Conclusion: The antimicrobial activity of Opuntia ficus-indica extract from Jeju Island by stem and fruit was determined at relatively low concentrations (250 mg/mL). The Opuntia ficus-indica extract will be useful for surface disinfectants dissolving the patients' bath, oral gargling, and powdered powder in water or ethanol in appropriate concentrations.

• Mycobiology
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• v.50 no.2
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• pp.110-120
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• 2022

The goal of the present study was to investigate the antibacterial properties, enzyme production, and metabolic profiling of a new Ceratorhiza hydrophila strain isolated from the submerged aquatic plant Myriophyllum spicatum. Furthermore, the fungus' morphological characterization and DNA sequencing have been described. The fungus has been identified and submitted to the GenBank as Ceratorhiza hydrophila isolate EG19 and the fungus ID is MK387081. The enzyme analyses showed its ability to produce protease and cellulase enzymes. According to the CSLI standard, the ethyl acetate extract of C. hydrophila showed intermediate antibacterial activity against Streptococcus pneumonia, Micrococcus luteus, and Staphylococcus aureus. Metabolic profiling has been carried out using 700 MHz NMR spectroscopy. Based on the ¹H and ¹H-¹³C heteronuclear single quantum coherence (HSQC) NMR data and NMR databases, 23 compounds have been identified. The identified metabolites include 31% amino acids, 9% sugars, 9% amines, 4% sugar alcohols, and 4% alkaloids. This is the first report for the metabolic characterization of C. hydrophila, which gave preliminary information about the fungus. It is expected that our findings not only will pave the way to other perspectives in enormous applications using C. hydrophila as a new promising source of antimicrobial agents and essential metabolites, but also it will be valuable in the classification and chemotaxonomy of the species.

• The Journal of the Korean Society for Microbiology
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• v.5 no.1
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• pp.27-31
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• 1970

Nalidixic acid and six other drugs were studied for in vitro effectiveness against 200 strains of Escherichia coli isolated recently from healthy persons and bactericidal activity of ampicillin against one respective strain of Escherichia coli and Salmonella typhi isolated were also studied. The resutlts obtained by the plate dilution method showed the following percentage of resistance: kanamycin, 2.5%; streptomycin, 12.0%; ampicillin, 13.5%; tetracyclin, 15.5%; chloramphenicol, 17.5%; colistin sulfate, 19.5%. No strains were resistant to nalidixic acid, clearly indicating that nalidixic acid is the most effective drug tested. Ampicillin, measured by test-tube diltion method, was highly bactericidal against Salmonella typhi at the concentration of 2.5mcg/ml and against Escherichia coli at 5mcg/ml.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1219-1222
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• 2010

A simple and efficient method has been developed for conversion of arenecarbaldehyde-3-methylquinoxalin-2-ylhydrazones to 3-(2-methylquinoxalin-3-yl)-2-(substitutedphenyl)thiazolidin-4-ones in good yields using microwave irradiation technique on silica as solid support under solvent free conditions. The synthesized compounds were characterized by elemental microanalysis, infrared spectroscopy, $^1H$ NMR, and mass spectroscopy. All the synthesized thiazolidinones were investigated for their antimicrobial and antifungal activities. The results of the biological activities revealed that the compounds 3b, 3d, 3f and 3h exhibited excellent antibacterial activities while 3d and 3h exhibited good antifungal activity.