• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2187-2190
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• 2013

• Journal of Applied Biological Chemistry
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• 제49권3호
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• pp.90-94
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• 2006

Bactericidal activity of grapefruit seed extract (GSE)-based disinfectant, as a safe disinfectant, was measured against five bacteria by Korean Food & Drug Administration (KFDA) dilution-neutralization method. GSE-based disinfectant showed a 99.9999% bactericidal activity against Escherichia coli ATCC 10536, Salmonella typhi ATCC 29629, Staphylococcus aureus ATCC 6538, Bacillus cereus ATCC 11778, and Listeria monocytogenes ATCC 1911 at the concentration of 2.15% GSE. It showed better bactericidal activity against Gram-negative bacteria of E. coli ATCC 10536 and S. typhi ATCC 29629 at lower concentration of GSE (0.43%). Based on the results, it was suggested that a possible bactericidal mechanism of GSE active ingredients was due to the abrupt osmotic shift during the bactericidal activity test by KFDA method.

• 한국어병학회지
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• 제5권1호
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• pp.9-18
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• 1992

어류의 방어기구를 밝히기 위하여, 잉어, 틸라피아 및 넙치의 혈청 중에 존재하는 보체의 살균작용에 대하여 실험하였다. 실험어의 모든 정상혈청으로 E. coli는 살균되었고 가열하여 보체를 불활성화시킨 혈청에서는 살균되지 않았다. zymosan으로 처리한 실험어의 정상혈청에서는 살균작용이 나타나지 않았으므로 정상혈청 중의 살균작용에도 보체의 대체경로가 중요한 것으로 생각되었다. EGTA로 처리한 틸라피아와 넙치의 정상혈청에서는 살균작용이 지속되고 있었으나, 잉어의 살균작용은 소실되는 점으로 봐서 잉어의 대체경로에는 $Ca^{2+}$이 요구되는 것으로 나타났다. 실험어의 정상혈청이 병원성이 있는 E. tarda에 대해서는 살균작용을 나타내지 않았고 병원성이 없는 E. coli에 대해서는 살균작용을 나타냈다. E. coli와 E. tarda는 면역혈청 중에서 모두 살균되었고 그 살균속도는 정상혈청에 비하여 빠른 것으로 나타났다.

• 미생물학회지
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• 제25권4호
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• pp.309-317
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• 1987

정상 상태의 연두금 파리 (Lucilia illustris) 제 3령충의 체액 (normal-haemolymph)으로 부터 그람양성 세균에 대하여 항균력이 있는 lysozymec (or lysozyme-like substance)을 확인하였으며 체벽을 손상시킨 체액 (injured-haemolymph)의 경우 그 항균력이 증가되었다. 특히 비병원성 세균인 Escherichia coli K-12로 면역하여 얻은 체액 (immune-haemolymph)의 경우 injured-haemolymph보다 그람양성 세율에 대하여 더 높은 항균력을 보였을 뿐만 아니라 그람음성 세균인 E. coli에 대하여 도 항균력을 나타내었다. Immune-haemolymph로 부터 유효 분획을 얻고 이에 대한 성상을 분석하기 위하여 Sephacryl S-300 및 CM-Sepharose CL-6B로 분리시킨 결과 상기 항균울질은 엽기성 만백질로서 산성하에서 내열성의 성질을 나타냈다.

• The Korean Journal of Physiology and Pharmacology
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• 제24권1호
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• pp.1-10
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• 2020

Autophagy is a highly conserved intracellular degradation and energy-recycling mechanism that contributes to the maintenance of cellular homeostasis. Extensive researches over the past decades have defined the role of autophagy innate immune cells. In this review, we describe the current state of knowledge regarding the role of autophagy in neutrophil biology and a picture of molecular mechanism underlying autophagy in neutrophils. Neutrophils are professional phagocytes that comprise the first line of defense against pathogen. Autophagy machineries are highly conserved in neutrophils. Autophagy is not only involved in generalized function of neutrophils such as differentiation in bone marrow but also plays crucial role effector functions of neutrophils such as granule formation, degranulation, neutrophil extracellular traps release, cytokine production, bactericidal activity and controlling inflammation. This review outlines the current understanding of autophagy in neutrophils and provides insight towards identification of novel therapeutics targeting autophagy in neutrophils.

• BMB Reports
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• 제30권3호
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• pp.229-233
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• 1997

Indolicidin has been known to have a broad spectrum of antimicrobial activities against Gram negative and positive bacteria. Its eight analogues were chemically synthesized. The analogue design was based on the analysis of sequence to elucidate the role of some residues in the antibacterial mechanism of indolicidin. Bactericidal activities were assayed against Escherichia coli and Proteus vulgaris, and the membrane perturbing abilities of the peptides were assayed using a dye containing liposome. Among the eight analogues, $[Gly^4, Gly^6]-Indo,\;[Ile^6,Ile^8]-Indo,\;[Lys^{12}]-Indo$ and $[Thr^2,Tyr^9]-Indo$ showed enhanced antibacterial activities. These results suggest that proline and cationic residues are important in the bactericidal activity of indolicidin. We tried to describe the antimicrobial mechanism of indolicidin with these results.

• The Korean Journal of Physiology and Pharmacology
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• 제26권3호
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• pp.175-182
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• 2022

Translocation of azurophil granules is pivotal for bactericidal activity of neutrophils, the first-line defense cells against pathogens. Previously, we reported that lysophosphatidylcholine (LPC), an endogenous lipid, enhances bactericidal activity of human neutrophils via increasing translocation of azurophil granules. However, the precise mechanism of LPC-induced azurophil granule translocation was not fully understood. Treatment of neutrophil with LPC significantly increased CD63 (an azurophil granule marker) surface expression. Interestingly, cytochalasin B, an inhibitor of action polymerization, blocked LPC-induced CD63 surface expression. LPC increased F-actin polymerization. LPC-induced CD63 surface expression was inhibited by both a Rho specific inhibitor, Tat-C3 exoenzyme, and a Rho kinase (ROCK) inhibitor, Y27632 which also inhibited LPC-induced F-actin polymerization. LPC induced Rho-GTP activation. NSC23766, a Rac inhibitor, however, did not affect LPC-induced CD63 surface expression. Theses results suggest a novel regulatory mechanism for azurophil granule translocation where LPC induces translocation of azurophil granules via Rho/ROCK/F-actin polymerization pathway.

• Journal of Microbiology and Biotechnology
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• 제27권10호
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• pp.1837-1843
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• 2017

Knowledge of avian host responses to brucellosis is critical to understanding how birds resist this infection; however, this mechanism is not well established. On the other hand, temperature has a major involvement in the physiology of living organisms, and cell death induced by heat is attributed to protein denaturation. This study demonstrates the direct bactericidal effect of a high temperature ($41^{\circ}C$) on Brucella abortus that resulted in the gradual reduction of intracellular bacteria and inhibited bacterial growth within avian macrophage HD11 in an increasing period of time. On the other hand, this study also revealed that high temperature does not affect the rate of bacterial uptake, as confirmed by the bacterial adherence assay. No significant difference was observed in the expression of target genes between infected and uninfected cells for both temperatures. This study suggests the susceptibility of B. abortus to bacterial death under a high temperature with an increased period of incubation, leading to suppression of bacterial growth.

• International Journal of Oral Biology
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• 제30권4호
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• pp.125-130
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• 2005

Thrombin-induced platelet microbicidal proteins (tPMP) are antibacterial proteins released when platelets are stimulated by thrombin. It has been reported that tPMP has antibacterial activity against various bacterial species including causative agents of infective endocarditis. Most of the oral streptococci have resistance to the killing by tPMP and this fact may play an important role as a virulence factor in infective endocarditis. However, the susceptibility and resistance mechanism of oral streptococci for tPMP have not been revealed yet. In this study, the killing mechanism of tPMP for oral streptococci has been investigated. Streptococcus rattus BHT, a susceptible strain, and Streptococcus gordonii DL1, a resistant strain, have been used in this study. tPMP was isolated from platelet after stimulation with thrombin. Cell membrane depolarization was examined with 3,3'-dipropylthiodicarbocyanine iodide ($DiSC_3$), membrane potential-sensitive cyanine dye, by fluorescence spectrophotometry. The permeabilization of cell membrane by tPMP was investigated with propidium iodide (PI) by flow cytometry. tPMP susceptible S. rattus BHT showed the increase of the $DiSC_3$ fluorescence level meaning depolarization of cell membrane and increase of the uptake of PI which means permeabilization of cell membrane. However, tPMP resistant S. gordonii DLI did not show depolarization and permeabilization. These results indicate that the increasing depolarization and permeabilization of oral streptococcal cell membrane are associated with the bactericidal activity of tPMP.

• Journal of Microbiology and Biotechnology
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• 제27권12호
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• pp.2129-2140
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• 2017

Silibinin is the major active component of silymarin, extracted from the medicinal plant Silybum marianum. Silibinin has potent antibacterial activity; however, the exact mechanism underlying its activity has not been elucidated. Here, we investigated the novel mechanism of silibinin against Escherichia coli. Time-kill kinetic assay showed that silibinin possess a bactericidal effect at minimal inhibitory concentration (MIC) and higher concentrations (2-and 4-fold MIC). At the membrane, depolarization and increased intracellular $Ca^{2+}$ levels were observed, considered as characteristics of bacterial apoptosis. Additionally, cells treated with MIC and higher concentrations showed apoptotic features like DNA fragmentation, phosphatidylserine exposure, and caspase-like protein expression. Generally, apoptotic death is closely related with ROS generation; however, silibinin did not induce ROS generation but acted as a scavenger of intracellular ROS. These results indicate that silibinin dose-dependently induces bacterial apoptosis-like death, which was affected by ROS depletion, suggesting that silibinin is a potential candidate for controlling bacteria.