• Biomedical Science Letters
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• v.13 no.1
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• pp.47-53
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• 2007

Due to wide abuse of antibiotics both in human and livestock use, the advent and spread of multidrug resistant (MDR) pathogens becomes a serious health problem all over the world. Since the development of new antibiotics is at a standstill in pharmaceutical industry, the choice of therapeutic antibiotics is getting narrower. In this study, in an effort to search new antibiotics, the antimicrobial activity of Paenibacillus DY1 isolated from Korean soil was characterized on its growth inhibition spectrum against various health threatening MDR strains, with its stability and chemical structure. Extracellular culture filtrate of Paenibacillus DY1 effectively inhibits the growth of all the tested MDR enteropathogenic Eshcherichia coli, enterohemolytic E. coli, and enterotoxigenic E. coli strains, at a similar level to that on the nonresistant control E. coli strains. It showed significant growth inhibition effect against the causative agents of class one legal communicable disease, MDR Salmonella typhi, MDR Salmonella paratyphi A, food poisoning bacteria, MDR Salmonella typhimurium, and other MDR Salmonella spp. The growth of all of 10 different MDR Shigella spp. strains and 6 different Vibrio spp. strains tested was also inhibited. The antimicrobial activity of Paenibacillus DY1 was well preserved after heat treatment, and was also stable in both alkaline and acidic environment. The antimicrobial activity was partially purified with Diaion HP20 column and TLC. By NMR study, the putative structure of the activity was postulated as an alkane having hydroxyl groups.

• BMB Reports
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• v.43 no.7
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• pp.468-473
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• 2010

Previously, various inhibitors of cell wall synthesis induced the drp35 gene of Staphylococcus aureus efficiently. To determine whether drp35 could be exploited in antistaphylococcal drug discovery, we cloned the promoter of drp35 ($P_d$) and developed different biological assay systems using an engineered S. aureus strain that harbors a chromosomally-integrated $P_d$ - lacZ transcriptional fusion. An agarose-based assay showed that $P_d$ is induced not only by the cell wall-affecting antibiotics but also by rifampicin and ciprofloxacin. In contrast, a liquid medium-based assay revealed the induction of $P_d$ specifically by the cell wall-affecting antibiotics. Induction of $P_d$ by sublethal concentrations of cell wall-affecting antibiotics was even assessable in a microtiter plate assay format, indicating that this assay system could be potentially used for high-throughput screening of new cell wall-inhibiting compounds.

• Microbiology and Biotechnology Letters
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• v.22 no.5
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• pp.459-466
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• 1994

Virginiae butanolide C(VB-C) is one of the butyrolactone autoregulators, which triggers the production of virginiamycin in Streptomyces virginiae. Streptomyces longwoodensis was selected as a test strain to investigate new VB-C functions. When 100 ng/ml of the synthetic VB-C was added into the culture at 5 hour and 0 hour, the initial production time of antibiotics and a dark blue pigment were shortened by 4~6 hours and 2~4 hours, respectively. HPLC analysis revealed the production of several new antibiotics by VB-C addition. In the SDS-PAGE analysis of the total protein from mycelium several new protein bands showed up and the amounts of certain protein bands increased in the presense of VB-C. The existence of specific VB-C binding protein was confirmed from S. longwoodensis in relation to VB-C signal transduction. These results suggest that the VB-C might have an ability to induce the production of secondary metabolites in Streptomy- ces longwoodensis.

• Proceedings of the PSK Conference
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• 2003.10a
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• pp.79-80
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• 2003

A lot of polyketide antibiotics have been isolated from natural sources like microorganism, fungi and plant. The polyketide natural products have biologically and medically important activities, including antibacterial, anticancer, antiparasitic, and immunosuppressant properties. The diversified activities of polyketides are originated from their structural variety of which have been took advantage by several research groups for development of new drugs. (omitted)

• Archives of Pharmacal Research
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• v.6 no.1
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• pp.93-102
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• 1983

Waksman's group discovered SM in 1944, and opened a new field of antibiotcs: i. e. AGs. A large group of antibiotics containing aminosugar and/or aminocyclitol is called the AGs. A majority of AGs are produced by actinomycetes. In the first period, AGs effective against tuberculosis were chiefly examined. Following the studies on NM and KM, AGs active against staphyllococci and gram-negative robs were investigated. The discovery of GM and synthesis of DKB and AMK led to the studies on the third generation AGs, which show a broad antimicrobial spectrum including Pseudomonas aeruginosa and drug-resistant bacteria. Since opportunistic infection caused by drug-resistant bacteria are increasing, the third generation AGs are extensively investigated at present.

• Journal of Microbiology and Biotechnology
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• v.10 no.2
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• pp.169-175
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• 2000

The filamentous soil bacterium Streptomyces coelicolor is known to produce four distinct antibiotics. The simultaneous global regulation for the biosynthesis of those four antibiotics was previously confirmed by absA and absB mutations that blocked all four antibiotics' biosynthesis without influencing their morphological differentiation. To study the complex regulatory cascade that controls the secondary metabolism in Streptomyces, a new abs-like mutation was characterized. namely absR, which is slightly leaky on a complete R2YE medium, yet tight on a minimal medium. A genetic analysis of the absR locus indicated that it is located at 10 o'clock on the genetic map, near the site of absA. A cloned copy of the absA gene that encoded bacterial two-component regulatory kinases did not restore antibiotic biosyntheis to the absR mutant. Accordingly, it is proposed that absR is another abs-type mutation which is less tight than the previously identified absA or absB mutations income medium conditions, and can be used to characterize another global regulatory gene for secondary metabolete formation in S. coelicolor.

• Journal of the Korean Society of Tobacco Science
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• v.17 no.2
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• pp.103-108
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• 1995

Antibiotic and physico-chemical properties of an active compound from actinomycetes isolate G-37, of which the culture filtrate had an inhibitory effect against tobacco mosaic virus(W) infection, were examined. The active compound, which was purified by ethylacetate extraction, silica gel column chromatography, preparative thin layer chromatography, and high performance liquid chromatography, showed strong antibacterial activities especially against Gram-positive bacteria including Bacillus subtillis, Sarcina lutea and Staphylococcus aureus. From the IH-NMR, FAB/RfS, UV spectral data, and physicochemical properties, the active compound of G-37 appears to belong to a peptide antibiotic group. Among the known peptide antibiotics in the antibiotic group, No. 280, A-30912, and Taitomycin showed molecular weights and ultra violet spectrum similar to those of the active compound from G-37, but was not identical to the compound, which suggests that it may be a new peptide antibiotics.

• Journal of Forest and Environmental Science
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• v.22 no.1
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• pp.83-100
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• 2006

Antibiotics which produced by mushrooms discovered for last 40 years were described. Any antibiotic has not been used as infectious disease remudy but will be used as physiological active substance in near future. The antibiotic of mushrooms have not been published much in papers and do not have various finds of structures, compared to those of Streptomyces. Triple bond having compounds, terpenoid compounds aromatic compounds and some other compound have been known. These compounds are not dissolved well in water and mainly fat-soluble, except for cordycepin. Also, they are generally neutral, and some of them are acidic and almost none of them are basic compounds. However, acetylene and terpenoid compounds are the characteristic compounds of mushroom, and are not found in other microorganisms and plants. Especially, there are various terpenoid compounds in mushrooms. These metabolites of mushrooms were not used as antibiotic, but are interested as physiological active substance, such as enzyme inhibitor and immunomodulator. To promote studying on the antibiotics of mushroom, new screening methods must be developed, because strain belonged to the different genus produces different antibiotics, even though mushrooms belonged to the same genus and species. It is also known that mushrooms collected in different areas produce different antibiotics. Now, it is difficult to separate each pure compound from mushroom. It is important to find mushrooms which is impossible to cultivate artificially, or grow in the back land where is difficult to collect. Thousands of mushrooms grow on earth now, so that which species will be screened if not known. The biochemical and mycological study for usability of the metabolites of mushrooms is thought, as one of the important research areas, must be performed.

• Microbiology and Biotechnology Letters
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• v.51 no.4
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• pp.432-440
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• 2023

Irrational and injudicious use of antibiotics, easy availability of them as over-the-counter drugs in economically developing countries, and unavailability of regulatory policies governing antimicrobial use in agriculture, animals, and humans, has led to the development of multi-drug resistance (MDR) bacteria. The use of medicinal plants can be considered as an alternative, with a consequent impact on microbial resistance. We tested extracts of Piper longum fruits as new natural products as agents for reversing the resistance to antibiotics. Six crude extracts of P. longum fruits were utilized against a clinical isolate of multidrug-resistant Staphylococcus aureus.The antibiotic susceptibility testing disc method was used in the antibiotic resistance reversal analysis. Apart from cefoxitin and erythromycin, all other antibiotics used (lincosamides [clindamycin], quinolones [levofloxacin and ciprofloxacin], and aminoglycosides [amikacin and gentamicin]) were enhanced by P. longum extracts. The extracts that showed the greatest synergy with the antibiotics were EAPL (ethyl acetate [extract of] P. longum), n-BPL (n-butanol [extract of] P. longum), and MPL (methanolic [extract of] P. longum The results of this study suggest that P. longum extracts have the ability to increase the effectiveness of different classes of antibiotics and reverse their resistance. However, future studies are needed to elucidate the molecular mechanisms behind the synergy between antibiotic and phytocompound(s) and identify the active biomolecules of P. longum responsible for the synergy in S. aureus.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.9
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• pp.4223-4231
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• 2016

Background: Development of new apoptosis-inducing drugs is a promising trend in anticancer therapy. For this purpose several formamidinoderivatives of doxorubicin were synthesized. The aim of our study was to investigate effects of the five formamidinodoxorubicins in the ES-2 human ovarian clear cell carcinoma line, for comparison with data obtained previously for SKOV-3 human ovarian adenocarcinoma cells, to answer the question of whether and to what extent the histological cell type is a possible determinant of sensitivity to tested anthracyclines. Materials and Methods: In our experimental work the following methods were used: spectrophotometric assays with MTT; fluorimetric assays - double staining with Hoechst 33258 and propidium iodide (PI), measurement of caspase-3, -8, -9 activity, intracellular accumulation of DOX and analogues, estimation of drug uptake, mitochondrial transmembrane potential; flow cytometry - phosphatidylserine (PS) externalization with annexin V-FITC and PI fluorochromes. Results: Effects of the derivatives of doxorubicin were partially linked with the specific type of cancer cell although intracellular accumulation and cellular uptake of DOX and derivatives were similar in both. All of the investigated derivatives were considerably more cytotoxic than DOX. Formamidinodoxorubicins were able to induce caspase-dependent apoptotic cell death in both cell types. Conclusions: All new formamidine derivatives of DOX were able to induce caspase - dependent apoptosis in human ovarian cancer cell lines SKOV-3 and ES-2. Obtained results suggested that formamidine derivatives of DOX may be promising candidates for the prospective chemotherapeutic agents for the two different histological subtypes of ovarian cancer.