• BMB Reports
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• v.32 no.1
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• pp.12-19
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• 1999

Gaegurin 4 (GGN4), a broad-spectrum antibiotic, is a 37-amino acid peptide isolated from the Korean frog, Rana rugosa. In this study, we have chemically synthesized and purified GGN4 analogues where the C-terminal portion is truncated and/or substituted with tryptophan. These peptides show significantly different biological activities depending on the location of tryptophan and the number of amino acids truncated from the C-terminal end. While deletion of 9 amino acids from the C-terminal seems to be marginally tolerable in maintaining the antimicrobial activity, further deletion of up to 14 amino acid residues decreases the potency by more than 60-fold towards Gram-positive, and 10-fold towards Gram-negative, bacteria. Surprisingly, the reduced activity of the shorter peptide can be completely restored by a single substitution of aspartic acid 16 to tryptophan 16 (D16W). Also, the truncation seems to decrease the specificity of antibiotic activity more towards Gram-positive than towards Gram-negative bacteria studied. These data suggest a partial role of the C-terminal region in determining the binding specificity and the activity of peptides upon binding to their target cell membranes.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.401-410
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• 2004

Soil samples from five different areas in Korea were collected during 2001/02 and examined for presence of the genus Clostridium. Direct immuno-fluorescent assay (IFA) examination showed that Clostridium septicum, Cl. novyi and Cl. chauvoei were detected in the soil of specific areas in Korea. Sixteen species of Clostridium were isolated and cultivated from the soil samples. Cl. peifringens was detected in all sampling locations, while the other species were not. The in vitro activity of 14 antibiotic agents was determined against 421 clostridia isolated from the soil contaminated with animal feces in Korea. Trovafloxacin was effective against all isolates of the genus Clostridium except one isolate of Cl. subterminale, two of Cl. tetani, and three of Cl novyi with $MIC_{50}$ $8- 16\mu$g $ml^{-1}$. Thirteen species of Clostridium were resistant to vancomycin except for Cl. perfringens, Cl. sporogenes, and Cl. subterminale. Imipenem and trovafloxacin showed high antimicrobial activities (>95%) against all strains in the clostridia investigated. Therefore, antibiotic agents such as imipenem and trovafloxacin are the most suitable agents for polymicrobial infection as broad-spectrum monotherapy.

• Journal of Food Hygiene and Safety
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• v.12 no.3
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• pp.228-233
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• 1997

Drug Dclivcry system (DDS) purpose to getting better remedial result by improving medication from ordinary methods. Applied for DDS, to improve selectivity and comtinuity during absorbing and delivery step, polmer drug (prodrug) was prepared by the esterification with dextran in such of biodegradable polymer and phthalylsulfathiazole with is efficient for entilitis. The polymer durg was prepared with dextran and phthalylsulfathiazole by the esterification. The synthetic procedures of polymer drug was performed by acid chloride and DCC methods. Polymer drug was synthesized in high yield by acid chloride method than DCC method. The antibiotic activities of polymer drug exhibited growth-inhibitory activity against Staphylococcus aureus, Staphylococcus epidermidis, E. coli, Salmonella typhimurium, Klebsiella pneumoniae at the concentration of 500 *g/m* in general through in vitro. As a result of test, polymer drug has 1/2 MIC than phthalylsulfathiazole. Also, it has high level MIC as much as phthalylsulfathiazole with Proteus, Pseudomonas. We conducted possibility of DDS as an applied for medicine with synthesized polymer drug by using natrural polymer. We consider that clinical research must be followed to verify safety and efficacy for controlled release, activity and toxicity.

• Korean Journal of Microbiology
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• v.37 no.4
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• pp.299-304
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• 2001

Teicoplanin is a kind of glycopeptide antibiotics produced by Actinoplanes teichomyceticus, and used in the clinical antibiotic such as vancomycin against methicillin-resistant Stabphylococcus aureus (MRSA). Actino planes teichomyceticus ATCC 31121 was mutated with UV to obtain a superior mutant strain with increased level of teicoplanin production. In this investigation, lethal curve was obtained and the optimal condition to induce mutagenesis was determined to isolate the desirable mutant strain. It was also confirmed that teicoplanin activities by agar diffusion method was compared with the parent strain. One mutant strain, T991014-1 with the highest productivity, was finally selected, and was characterized through the various tests such as amylase activity, protease activity, halotolerance, antibiotic resistance, autotoxicity, and productivity. Ad fermentation characteristics of the mutant strain were also studied.

• Applied Biological Chemistry
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• v.38 no.6
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• pp.516-521
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• 1995

In order to find a potent anti-methicillin resistant Staphylococcus aureus (MRSA) antibiotic, actinomycetes isolated from the samples collected in Korean marine silt were screened. From the culture broth of the isolated Streptamyces strain AM045, a substance showing excellent biological activity against MRSA was found, isolated and named AM3. The compound showed strong activities against MRSA, S. epidermidis, E. faecium and E. faecalis, which were better than those of vancomycin and teicoplanin. Unfortunately, AM3 was identified as Actinomycin V. However, this paper reports the three dimensional study of AM3 based on high resolution nmr and Computer Aided Molecular Modeling(CAMM), and the fact that the structure of the pentapeptide lactone ring with oxo-proline in chloroform solution does not have 'C conformation' any more.

• The Plant Pathology Journal
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• v.35 no.4
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• pp.341-350
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• 2019

Streptomyces padanus PMS-702 strain produces a polyene macrolide antibiotic fungichromin and displays antagonistic activities against many phytopathogenic fungi. In the present study, experimental formulations were assessed to improve the production of fungichromin, the efficacy of PMS-702 on the suppression of sporangial germination, and the reduction of cucumber downy mildew caused by Pseudoperonospora cubensis. PMS-702 strain cultured in a soybean meal-glucose (SMG) medium led to low levels of fungichromin accumulation and sporangial germination suppression. Increasing medium compositions and adding plant oils (noticeably coconut oil) in SMG significantly increased fungichromin production from 68 to $1,999.6{\mu}g/ml$. Microscopic examination reveals that the resultant suspensions significantly reduced sporangial germination and caused cytoplasmic aggregation. Greenhouse trials reveal that the application of PMS-702 cultural suspensions reduced downy mildew severity considerably. The addition of Tween 80 into the synthetic medium while culturing PMS-702 further increased the suppressive efficacy of downy mildew severity, particularly when applied at 24 h before inoculation or co-applied with inoculum. Fungichromin at $50{\mu}g/ml$ induced phytotoxicity showing minor necrosis surrounded with light yellowish halos on cucumber leaves. The concentration that leads to 90% inhibition (IC90) of sporangial germination was estimated to be around $10{\mu}g/ml$. The results provide a strong possibility of using the S. padanus PMS-702 strain as a biocontrol agent to control other plant pathogens.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.985-990
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• 1995

Grapefruit seed extracts(GFSE) have some unknown compounds which exhibit the antibiotic activities aganist microorganisms including bacteria and fungi. We have examined the effects of GFSE on the growth of Enterobacter pyrinus which was isolated from necrotic lesions of pear trees. During the cultivation, the growth of the bacteria was strongly inhibited at the low concentration(0.01%, w/w) of GFSE. Hydrophobic fraction extracted from GFSE by mixed solvents (chloroform : methanol : water, 1 : 2 : 0.8, v/v/v) had components which inhibited the growth of bacteria. There was, however, no inhibitory effect of GFSE on the activities of several enzymes including hexokinase, glucose 6-phosphate dehydrogenase, malate dehydrogenase and succinate dehydrogenase. $O-nitrophenyl-{\beta}-D-galactopyranoside(ONPG)$, the artificial substrate of ${\beta}-galactosidase$ was hydrolyzed in the presence of GFSE, indicating that the membrane was pertubated by the GFSE. From the results it was suggested that the antibiotic activity of GFSE is due to the change of membrane permeability of cell. GFSE was fractionated by high performance liquid chromatography equipped with $C_{18}$ reverse phase column. Among active fractions, three peaks were identified as 1-chloro-2-methyl-benzene (o-toluene), N,N-dimethyl-benzenemethaneamine, 1-[2-(2-ethylethoxy)ethoxy]-4- (1,1,3,3-tetramethyl)-bezene, respectively, while the other three remained unidentified.

• The Korean Journal of Mycology
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• v.24 no.1 s.76
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• pp.25-37
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• 1996

Antifungal and antibacterial activities of 108 extracts from 36 species of mushrooms in Korea were screened. The powder of fruiting body of each mushroom was extracted with petroleum ether, 80% ethanol and distilled water subsequently. Among these, five extracts including the ethanol extract of Agaricus subrutilescens, seven extracts including the water extract of Amanita virosa, nine extracts including the water extract of Amanita pantherina and twenty five extracts including the water extract of Lycoperdon perlatum showed antibiotic activities against yeasts, fungi, Gram-negative bacteria and Gram-positive bacteria, respectively.

• Food Science and Preservation
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• v.11 no.3
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• pp.417-423
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• 2004

Botanical antimicrobial agent-grapefruit seed extract mixture (BAAG) have an unknown compounds which exhibit the antibiotic activities aganist microorganisms including bacteria and fungi. We have examined the effects of BAAG on the physiological function of Botrytis cinerea which was isolated from necrotic lesions of decayed fruits and vegetables such as cucumbers, grapes, tomatoes, and red peppers during storage. In the results of enzymatic activities related to the energetic metabolism there was no inhibitory effect of BAAG on the activities of several enzymes in vitro including glucose 6-phosphate dehydrogenase and malate dehydrogenase, while there was inhibitory effect of BAAG on the activities of hexokinase and succinate dehydrogenase. O-nitrophenyl-$\beta$-D-galactopyranoside(ONPG), the artificial substrate of $\beta$-galactosidase was hydrolyzed in the presence of BAAG, indicating that the membrane was pertubated by the BAAG. From the results we suggested that the antibiotic activity of BAAG is due to the change of membrane permeability of the cell. BAAG was fractionated and purified by silica gel and sephadex column chromatography. Among active fractions two peaks were identified as naringin and limonin when they were analyzed by by NMR and Fast atomic bombardment.

• Analytical Science and Technology
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• v.18 no.6
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• pp.500-510
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• 2005

This study was conducted to investigate the chemical composition of essential oil, absolute and oleoresin isolated from Elsholtzia splendens and their biological activities. Yields of essential oil, absolute and oleoresin extracted from Elsholtzia splendens were 0.28%, 12.45% and 9.95%, respectively. The major component was 2-cyclohexen-1-one in essential oil, methyl linolenate in absolute and 9,12,15-octadecatrienoic acid in oleoresin. Essential oil and oleoresin showed the inhibitory activities in enzyme-dependent, enzyme-independent and autooxidative lipid peroxidation system. $EC_{50}$ values in nuetral red uptake (NRU) assays for the exposure times of 24 h were $46.4{\mu}g/ml$, $681.7{\mu}g/ml$ and $17.6{\mu}g/ml$ in essential oil, absolute and oleoresin, and oleoresins showed the cytotoxic effect at the only high dose. Any mutagenic and antibiotic activity did not show in absolute and oleoresin, but, there were mutagenic and antibiotic activities only when treated with essential oil $500{\mu}g/ml$ above in Ames test. Essential oil and oleoresin might be somewhat effective in prolongating the ciliostasis of rat trachea.