• Journal of Microbiology and Biotechnology
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• v.17 no.3
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• pp.403-407
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• 2007

Several marine. bacterial strains, which were isolated from seawater off the island Dokdo, Korea, were screened to find new bioactive compounds such as antibiotics. Among them, Donghaeana dokdonensis strain DSW-6 was found to produce antibacterial agents, and the agents were then purified and analyzed by LC-MS/MS and 1D- and 2D-NMR spectrometries. The bioactive compounds were successfully identified as cholic acid and glycine-conjugated glycocholic acid, the $7{\alpha}$-dehydroxylated derivatives (deoxycholic acid and glycodeoxycholic acid) of which were also detected in relatively small amounts. Other marine isolates, taxonomically different from DSW-6, were also able to produce the compounds in a quite different production ratio from DSW-6. As far as we are aware of, these bile acids are produced by specific members of the genus Streptomyces and Myroides, and thought to be general secondary metabolites produced by a variety of bacterial taxa that are widely distributed in the sea.

• Journal of fish pathology
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• v.16 no.1
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• pp.61-68
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• 2003

MICs of 8 chemotherapeutic agents against forty streptococcal isolates were determined. These strains were isolated from diseased olive flounder, Paralichthys olivaceus, and showed 2-5 multiple drug resistance against different antibacterial agents including ampicillin, doxycycline (DOXY), erythromycin, florfenicol, flumequine, norfloxacin, oxolinic acid, and oxytetracycline (OTC). In conjugation experiment, we found transferable R plasmids carrying OTC and DOXY resistance determinant in 3 drug resistance strains analyzed. Six out of 40 isolates showed positive signal in colony hybridization with the R plasmid DNA (pST9) as a probe. It suggests that other types R plasmid different from pST9 is also involving in multiple drug resistance of streptococci isolated from olive flounder.

• Genomics & Informatics
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• v.21 no.1
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• pp.5.1-5.13
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• 2023

Neisseria gonorrhoeae is a Gram-negative aerobic diplococcus bacterium that primarily causes sexually transmitted infections through direct human sexual contact. It is a major public health threat due to its impact on reproductive health, the widespread presence of antimicrobial resistance, and the lack of a vaccine. In this study, we used a bioinformatics approach and performed subtractive genomic methods to identify potential drug targets against the core proteome of N. gonorrhoeae (12 strains). In total, 12,300 protein sequences were retrieved, and paralogous proteins were removed using CD-HIT. The remaining sequences were analyzed for non-homology against the human proteome and gut microbiota, and screened for broad-spectrum analysis, druggability, and anti-target analysis. The proteins were also characterized for unique interactions between the host and pathogen through metabolic pathway analysis. Based on the subtractive genomic approach and subcellular localization, we identified one cytoplasmic protein, 2Fe-2S iron-sulfur cluster binding domain-containing protein (NGFG RS03485), as a potential drug target. This protein could be further exploited for drug development to create new medications and therapeutic agents for the treatment of N. gonorrhoeae infections.

• Journal of Life Science
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• v.24 no.7
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• pp.757-761
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• 2014

Olive flounder (Paralichthys olivaceus) is an important aquaculture fish species in Jeju Island, South Korea. Due to the intensification of flounder fish farming, huge amounts of chemical antibiotics are used against several fish diseases. This has many harmful side effects on fish, as well as human consumers. Hence, an alternative to chemical antibiotic agents is needed for disease control. In this study, three strains of rhizobacteria (BRH433-2, TRH415-2, and THJ609-3) were isolated from the rhizosphere of plants. Assays of their antibacterial activity against fish pathogens, such as S. iniae, S. parauberis, V. anguillarum, and E. tarda, were performed with untreated broth culture (without cell separation), supernatant, and precipitated pellets separated by centrifugation. Among these, the cell suspension prepared from the precipitated pellet showed significant antimicrobial activity when compared with that of the untreated broth culture and centrifugal supernatant. These results indicate that the three isolated rhizobacterial strains exhibit antibacterial activity. Analysis of the 16S rDNA sequences of the BRH-433-2, THJ609-3, and TRH415-2 strains showed the highest similarity to Burkholderia gladioli (99.5%), Pseudomonas baetica (97.7%), and P. koreensis and P. baetica (98.4%), respectively. We suggest that the strains hold promise in disease management of fish.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.3
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• pp.269-277
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• 2015

Herbal plant extracts are good resources to find functional compounds for cosmetic ingredient. In this study, the extract of Areca semen (A. semen) was studied for melanogenesis inhibition and antioxidant activity. The results showed that ethyl acetate fraction of A. semen contained phenolic contents, $301.35{\pm}0.88{\mu}g/mg$, and exhibited potent antioxidant activity with $IC_{50}$ value of $1.02{\pm}0.07{\mu}g/mg$. Further, FRAP value exhibited potent antioxidant activity with $9.07{\pm}0.36mM$. Disk diffusion assay was performed for antibacterial activity. Ethyl acetate fraction of A. semen showed antibacterial activity against Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) at $80{\mu}g/mL$, whereas it showed no significant antibacterial activity against Escherichia coli (E. coli). The results of cell viability indicated that ethyl acetate fraction did not show cytotoxicity to B16/F1 cells at $80{\mu}g/mL$ and showed significant cytotoxicity at $100{\mu}g/mL$ of concentration and showed inhibition of melanin synthesis inhibitory, $29.78{\pm}0.31%$ at $80{\mu}g/mL$. Furthermore, mRNA expressions of tyrosinase and MITF were decreased after treatment with ethyl acetate fraction in a dose-dependent manner. As a result, the ethyl acetate fraction of A. semen could be considered as potential as whitening agents.

• Journal of Life Science
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• v.31 no.9
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• pp.862-872
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• 2021

Recent studies on synthesis of metallic nanomaterials such as silver (Ag), gold (Au), platinum (Pt), cerium (Ce), zinc (Zn), and copper (Cu) nanoparticles (NPs) using plants and microbes are attracted researchers for their wide range of applications in the field of biomedical sciences. The plant contains abundant of bioactive contents such as flavonoids, alkaloids, saponins, steroids tannins and nutritionals components. Similarly, microbes produce bioactive metabolites, proteins and secretes valuable chemicals such as color pigments, antibiotics, and acids. Recently reported, biogenic synthesis of NPs in non-hazardous way and are promising candidates for biomedical applications such as antibacterial, antifungal, anti-cell proliferative and anti-plasmodia activity. All those activities are dose dependent, along with their shape and size also matters on potential of NPs. Microbes and plants are great source of metabolites, those useful in biomedical field, such metabolites or chemicals involved in synthesis of NPs in an ecofriendly way. NPs synthesized using microbes or plant materials are reveals more non-toxic, facile, and cost-effective compare to chemically synthesized NPs. In present review we are focusing on NPs synthesis using biological agents such as microbes (bacteria, fungi and algae) and plant, characterization using different techniques and their antibacterial applications on pathogenic Gram-positive and Gram-negative organisms.

• Bulletin of the Korean Chemical Society
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• v.32 no.11
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• pp.3996-4000
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• 2011

In an attempt to find a new class of anti microbial agents, a series of thiazolidinone and their 5-arylidene derivatives containing 4-(4-methyl benzamido)-benzoyl moiety were synthesized via the reaction of benzocaine with appropriate chemical reagents. These compounds were screened for their antibacterial activity against Gram-positive bacteria (Bacillus subtilis and Bacillus thuringiensis), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and antifungal activity against Botrytis fabae, Fusarium oxysporan and Candida albicans. On the other hand the synthesized compounds were also screened for their anti tubercular activity. IR, $^1H$ NMR, $^{13}C$ NMR and MS spectral analyses established the structures of the newly synthesized compounds. The results revealed that some of these compounds have shown promising antimicrobial and anti tubercular activity in comparison with standard drugs.

• Journal of the Korean Chemical Society
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• v.55 no.5
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• pp.781-786
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• 2011

An easy and efficient route for the synthesis of some imidazo[1,2-c]pyrazolo[4,3-e]pyrimidines 3-6, imidazo[1,2-c]pyrazolo[4,3-e]triazine 8, pyrazolo[4,3-e]triazolo[1,5-c]pyrimidines 12-15 and pyrazolo-[3',4':4,5]pyrimido[1,6-b]triazines 16, 17 was described through the reaction of readily available 5-aminopyrazole-4-carbonitrile 1 with different reagents. The in vitro antimicrobial activity of some synthesized compounds was examined. Most of the tested compounds proved to be active as antibacterial and antifungal agents.

• Journal of Microbiology and Biotechnology
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• v.27 no.4
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• pp.759-767
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• 2017

Lactophoricin (LPcin), which is a part of proteose peptone isolated from bovine milk, is a cationic amphipathic ${\alpha}-helical$ antimicrobial peptide. Its truncated variants and mutated analogs were designed and their antimicrobial activities were evaluated by using various assays, like broth dilution methods and disk diffusion methods as well as hemolysis assay. Three analogs, LPcin-C8 (LPcin-YK1), LPcin-T2&6W (LPcin-YK2), and LPcin-T2&6W-C8 (LPcin-YK3), which showed better antibiotic activities than LPcin, were selected. Their secondary structures were also characterized by using CD spectropolarimetry. These three analogs of LPcin could be used as an alternative source of powerful antibacterial agents.

• Journal of Food Hygiene and Safety
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• v.8 no.1
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• pp.1-8
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• 1993

육류중에 잔류하는 항생물질 및 항균제를 검출하기 위해 본 실험에서는 3종의 균주 Bacillus subtilis ATCC 6633, Micrococcus luteus ATCC 9341, BAcillus cereus var. mycoides ATCC 11778을 사용하여 실험하였다. 시료의 clean-up은 항생·항균제의 물리화학적 성질을 고려하여 우선 McIlvaine buffer를 가하여 homogenize하고 hexane으로 defatting 시킨 후, chloroform으로 추출한 액과 Sep-Pak C18과 Bakerbond SPE carboxylic acid column에 흡착시킨 후 추출한 액을 각각 시험용액 A, B, C,로 하였다. 각 test solution을 paper disk를 사용하여 함균 배지에 올려놓고 overnight culture 후 inhibition pattern을 통해 여러 종류의 항생·항균제를 계통적으로 검출하였다. 본 실험에서 macrolide계와 tetracycline계 등은 0.1ppm 이하의 detection limit을 보였으며, penicillinrP는 0.001ppm이하의 높은 detection limit을 나타내므로서 시료중에 잔류하는 극미량까지도 검출할 수 있었다. 본 방법은 식육중의 잔류 항생·항균제를 동시에 간단하게 계통적으로 분류하는데 있어 좋은 방법이라고 생각되며 항생·항균제의 체계적인 1차 screening 수단으로서 유용한 방법이라 사료된다.