• KSBB Journal
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• 제27권1호
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• pp.9-15
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• 2012

Antimicrobial peptides are widely used in various organisms as a defense system against infection. The peptides are lethal towards bacteria and fungi, however have minimal toxicity in mammalian and plant cells. In this aspect, it is considered that antimicrobial peptides are new alternative materials for defensing against microbial infection. Here, we describe overall characteristics of antimicrobial peptides based on the mechanism of action, classification of the peptides, report detection/screening methods and chemical/biological production. It is expected that understanding of innate immune system based on antimicrobial peptides tends to develop novel natural antimicrobial agents, which might be applied for defensing pathogenic microorganisms resistant to conventional antibiotics.

• 한국미생물·생명공학회지
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• 제25권3호
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• pp.240-247
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• 1997

Bacillary is the most common form of H. pylori observed during human infection. However, it is known that the morphology change of H. pylori from bacillary to coccoid can be occurred with a response to the environmental stresses such as the nutrient depletion, accumulation of toxic metabolites, pH alteration, and exposure to antimicrobial agents. The coccoid form of H. pylori, which is viable but non-culturable in vitro, seems to be the major cause of antibiotic resistancy and high reinfectability of H. pylori. In this regard, we studied the environmental factors that can induce the morphological change in vitro of H. pylori, and the change of fatty acid composition of plasma membrane. The morphological change from bacillary to coccoid could be observed with the depletion of nutrients, pH variation and reactive oxygen species added in the culture media. This morphologic conversion was paralleled by a dramatic decrease in unsaturated fatty acids and an increase in saturated fattv acids of plasma membrane. The change in composition of membrane fatty acid seems to be a kind of protection mechanism of H. pylori against these environmental stresses.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.77.1-77.1
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• 2003

Prolongation of the QT interval may result in a potentially dangerous arrhythmia. The most commonly proposed mechanism for QT interval prolongation(LQT) by pharmaceuticals is inhibition of the rapid delayed rectifier potassium channel (I$\sub$Kr). The LQT potency of pharmaceuticals can be effectively evaluated by examining the effect on human ether-a go-go-related gene (hERG) channels expressed in CHO cells, known to be equal to I$\sub$kr/. We have transfected JERG into CHO cell lines transiently to express high levels of functional hERG channels. (omitted)

• Journal of Microbiology and Biotechnology
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• 제4권4호
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• pp.296-304
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• 1994

Antibiotic substances were produced by Bacillus subtilis YB-70, a potential biocontrol agent found to suppress root-rot of eggplant (Solanum melonggena L) caused by Fusarium solani, in a dextrose glutamate medium and isolated by isoelectric precipitation. Partial purification was performed by column chromatography on silica gel with two solvent systems: chloroform-methanol and methanol-chloroform-water as eluting solvents, This active fraction YBS-1 s contained antifungal activity were soluble in ethanol, methanol, and water, but were not soluble in other solvents including acetone, butanol, ethyl ether, dimethylformamide, propanol, and etc. High performance liquid chromatography and thin layer chromatographic separation of YBS-1s showed that they have been composed of three biological active bands that were named YBS-1A, -1B, and -1C. The substances were stable to heat and resistant to protease. YBS-1s were active against a wide range of plant pathogenic fungi but did not inhibit the growth of bacteria and yeasts. They were not only fungicidal but also fungistatic against chlamydospores of F. solani. The $ED_{50}$ values for the chlamydospore germination and the germ-tube growth of F. solani were $O.725\mu\textrm{m}/ml\;and\;O.562\mu\textrm{m}/ml$, respectively. Microscopic observations proved the substances restricted the growth of phytopathogenic fungus F. solani by spore burst followed by dissolving of its germ-tube, and caused abnormal hyphal swelling after application to chlamydospores or growing hyphae. Cultural filtrate of B; subtilis YB-70 also suppressed the development of root-rot of eggplant in pot tests.

• Journal of Microbiology and Biotechnology
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• 제22권11호
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• pp.1457-1466
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• 2012

Antimicrobial peptides (AMPs) exert antimicrobial activity against Gram-positive and Gram-negative bacteria, fungi, and viruses by various mechanisms. AMPs commonly possess particular characteristics by harboring cationic and amphipathic structures and binding to cell membranes, resulting in the leakage of essential cell contents by forming pores or disturbing lipid organization. These membrane disruptive mechanisms of AMPs are possible to explain according to the various structure forming pores in the membrane. Some AMPs inhibit DNA and/or RNA synthesis as well as apoptosis induction by reactive oxygen species (ROS) accumulation and mitochondrial dysfunction. Specifically, mitochondria play a major role in the apoptotic pathway. During apoptosis induced by AMPs, cells undergo cytochrome c release, caspase activation, phosphatidylserine externalization, plasma or mitochondrial membrane depolarization, DNA and nuclei damage, cell shrinkage, apoptotic body formation, and membrane blebbing. Even AMPs, which have been reported to exert membrane-active mechanisms, induce apoptosis in yeast. These phenomena were also discovered in tumor cells treated with AMPs. The apoptosis mechanism of AMPs is available for various therapeutics such as antibiotics for antibiotic-resistant pathogens that resist to the membrane active mechanism, and antitumor agents with selectivity to tumor cells.

• Applied Biological Chemistry
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• 제48권1호
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• pp.40-47
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• 2005

진균성식물병을 생물학적으로 방제할 수 있는 미생물제제의 개발을 위하여 경북 지역의 저병해 경작지 토양에서 고추역병균 Phytophthota capsici과 시들음병균 Fusarium oxysporum에 강력한 길항능을 가지며 균주 상호간에 공생이 가능한 AY1, AY6, AB1, BB2, F4, 5종의 균주를 선발하였다. 이들의 P. capsici에 대한 길항기작은 모두 내열성 저분자의 항균성 항생물질 생산에 의한 것이었으며, 이 중 BB2균주는 항생물질 생산능뿐만 아니라 고추역병균의 세포의벽 가수분해효소인 cellulase도 생산하여 다기능 길항기작을 보유하고 있었다. 선발된 5종 균주는 Halobacterium sp. AB1, Xenorhadus sp. AY1, Bacillus sp. AY6, Bacillus sp. BB2, Zymomonas sp. F4로 각각 동정되었으며, 이들은 0.1% galactose, 0.1% $NaNO_2$, 5 mM $Na_2HPO_4$가 포함된 배지에서 pH 5.5의 조건에서 48시간 배양했을 때 길항물질 생산능이 매우 우수하였고, 이 배양액을 1톤 규모의 발효탱크에 접종하고 대량배양 후 복합 미생물제제로 생산하였으며, 생산된 시제품의 액상 미생물제제는 경북 영천지역의 농가의 시험포장에서 3일 간격으로 3회 처리 해 본 포장시험에서 오이덩굴쪼김병, 방울토마토시드름병의 방제와 시금치잘록병의 방제 및 생육촉진에 탁월한 효과가 있었다.

• 한국미생물·생명공학회지
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• 제33권3호
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• pp.194-199
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• 2005

토마토시들음병의 원인균인 Fusarium oxysporum의 생물학적 방제를 위해 경북지역의 저병해경작지로부터 항진균성 항생물질 생산성 길항미생물인 BK4 균주를 선발하였으며, 길항균주 BK4의 16S rDNA 분석 및 생화학적 특성 조사 후 최종적으로 Biolog사 동정시스템인 $MicroLog^{TM}$ 3.0을 이용하여 선발 길항균주 BK4를 Bacillus thuringiensis BK4로 동정하였다. B. thuringiensis BK4는 pH 9.0로 적정한 Nutrient broth를 이용하여 $30^{\circ}C$에서 배양할 경우 항생물질의 생산은 최대였다. B. thuringiensis BK4가 생산하는 항생물질은 $121^{\circ}C$에서 열처리시에도 $80{\%}$ 잔존활성을 유지한 내열성 항생물질이었으며, pH $3.0{\~}12.0$의 범위에서 활성의 변화를 조사한 결과 산성보다는 알칼리성에서 다소 안정적이였으나 pH 3.0에서도 $50{\%}$ 이상의 잔존 활성을 가지고 있다. B. thuringiensis BK4는 F. oxysporun에 의한 토마토시들음병에 대하여 in vivo pot상에서도 충분한 방제력을 나타내었으므로 토마토시들음병을 위시한 Fusarium속 균주가 원인이 되는 질병을 방제할 수 있는 미생물제제의 개발이 가능하게 되었다.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2000년도 Proceedings of 2000 KSAM International Symposium and Spring Meeting
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• pp.3-6
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• 2000

Antimicrobial resistance has been a well-recognized problem ever since the introduction of penicillin into clinical use. History of antimicrobial development can be categorized based on the major antibiotics that had been developed against emerging resistant $pathogens^1$. In the first period from 1940 to 1960, penicillin was a dominating antibiotic called as a "magic bullet", although S.aureus armed with penicillinase led antimicrobial era to the second period in 1960s and 1970s. The second stage was characterized by broad-spectrum penicillins and early generation cephalosporins. During this period, nosocomial infections due to gram-negative bacilli became more prevalent, while those caused by S.aureus declined. A variety of new antimicrobial agents with distinct mechanism of action including new generation cephalosporins, monobactams, carbapenems, ${\beta}$-lactamase inhibitors, and quinolones characterized the third period from 1980s to 1990s. However, extensive use of wide variety of antibiotics in the community and hospitals has fueled the crisis in emerging antimicrobial resistance. Newly appeared drug-resistant Streptococcus pneumoniae (DRSP), vancomycin-resistant enterococci (VRE), extended-spectrum ${\beta}$-lactamase-producing Klebsiella, and VRSA have posed a serious threat in many parts of the world. Given the recent epidemiology of antimicrobial resistance and its clinical impact, there is no greater challenge related to emerging infections than the emergence of antibiotic resistance. Problems of antimicrobial resistance can be amplified by the fact that resistant clones or genes can spread within or between the species as well as to geographically distant areas which leads to a global concern$^2$. Antimicrobial resistance is primarily generated and promoted by increased use of antimicrobial agents. Unfortunately, as many as 50 % of prescriptions for antibiotics are reported to be inappropriate$^3$. Injudicious use of antibiotics even for viral upper respiratory infections is a universal phenomenon in every part of the world. The use of large quantities of antibiotics in the animal health industry and farming is another major factor contributing to selection of antibiotic resistance. In addition to these background factors, the tremendous increase in the immunocompromised hosts, popular use of invasive medical interventions, and increase in travel and mixing of human populations are contributing to the resurgence and spread of antimicrobial resistance$^4$. Antimicrobial resistance has critical impact on modem medicine both in clinical and economic aspect. Patients with previously treatable infections may have fatal outcome due to therapeutic failure that is unusual event no more. The potential economic impact of antimicrobial resistance is actually uncountable. With the increase in the problems of resistant organisms in the 21st century, however, additional health care costs for this problem must be enormously increasing.

• 대한약리학회지
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• 제29권1호
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• pp.131-137
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• 1993

Tetracycline계 약제가, 류마치양 관절염을 비롯한 염증성 질환들의 주된 병인으로 알려지고있는 호중구 elastase의 활성도를 억제하였으며, 특히 oxytetracycline, demeclocycline, 그리고 tetracycline 등은 분자 구조적 차이에 따라 elastase의 효소 활성도에 대하여 다양한 억제율을 나타내었다. 측쇄 구조의 5번 위치에 $OH{^-}$기가 첨가된 oxytetracycline이 가장 높은 억제율을 나타내었다. 억제 양상에 있어서도 tetracycline이 비경쟁적 저해 형태를 보인 반면에, oxytetracycline은 경쟁적 저해 형태를 나타내었으며, Ki값은 각각 4.9mM과 0.39mM로 산출 되었다. 또한 항균 효과를 나타내는 활성 부위를 제거시킨 de-dimethylaminotetracycline을 합성하여 효소 활성도 억제 실험에 사용한 결과, tetracycline과 유사한 효소 억제 작용을 나타냄을 확인하였다. 이상의 연구 결과에서, tetracycline의 효소 활성도 억제 작용은 항균 효과를 나타내는 활성 부위와 상관없이 독립된 기전에 의해서 일어나는 약리 작용이며, 측쇄 구조의 $OH{^-}$기가 이 작용에 영향을 주는 일부 원인인 것으로 추정할 수 있으며, 이를 tetracycline계 약제가 염증 부위에서 나타내는 분자 단계에서의 새로운 약리 기전으로 제시하고자 한다. 또한 de-dimethylaminotetracycline은 항균제의 장기 사용시에 발생할 수 있는 저항균의 출현과는 무관하므로, 다른 부작용에 대한 연구가 선행될 경우, elastase에 의해 야기되는 만성 질환들의 치료제로써 중요한 역할을 할 것으로 사료된다.

• 대한본초학회지
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• 제32권2호
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• pp.87-95
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• 2017

Objectives : Infectious diseases by Methicillin-Resistant Staphylococcus aureus (MRSA) are a growing problem worldwide. Characteristic of MRSA is endlessly mutation to resist antibiotics. Daehwanggo (DHG) is one of the oriental medicine prescriptions contained in Principles and Practice of Eastern Medicine. Daehwanggo was mainly used for external preparation from old times. The purpose of this study is to confirm possibility as supplementary drug of DHG about antibiotics through observation of synergy effect between DHG and commercial antibiotics and to observe restriction on growth of MRSA on any pathway through observation of mechanism. Methods : The minimum inhibitory concentration (MIC) of DHG against MRSA is $500{\sim}2000{\mu}g/m{\ell}$ by broth dilution method. In the checkerboard method, the combinations of DHG with antibiotics has partial synergistic effect or synergy effect and DHG markedly reduced the MICs of the antibiotics oxacillin (OX), gentamicin (GT) against MRSA. In the inhibition of resistance mechanism of DHG against MRSA, the expression of resistance gene and protein about ${\beta}-lactam$ antibiotic was reduced. Also, we observed the effect of DHG about cell membrane permeability against MRSA, and confirmed that DHG suppressed growth of strains by increasing cell membrane permeability. Results : Basis on the result, we speculate that DHG increase antibacterial activity of antibiotics against MRSA by changing the structure of cell wall of MRSA. Conclusions : These data suggest that Daehwanggo possesses possibility as supplementary drug about antibiotics against MRSA.