• Journal of Microbiology and Biotechnology
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• v.34 no.8
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• pp.1680-1687
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• 2024

The diverse pharmacological properties of edible bird's nest (EBN) have been elucidated in recent years; however, investigations into its antibacterial effects are still limited. In the present study, we explored the antibacterial activity of a peptide-rich extract of EBN against Staphylococcus aureus, a notorious pathogen. The EBN extract (EEE) was prepared by soaking EBN in 80% ethanol for 2 days at 60℃. Biochemical analyses showed that peptides at the molecular weight range of 1.7-10 kDa were the major biochemical compounds in the EEE. The extract exhibited strong inhibition against S. aureus at a minimum inhibitory concentration (MIC) of 125 ㎍/ml and a minimum bactericidal concentration (MBC) of 250 ㎍/ml. This activity could be attributed to the impact of the extract on cell membrane integrity and potential, biofilm formation, and reactive oxidative species (ROS) production. Notably, the expression of biofilm- and ROS-associated genes, including intercellular adhesion A (icaA), icaB, icaC, icaD, and superoxide dismutase A (sodA), were deregulated in S. aureus upon the extract treatment. Our findings indicate a noteworthy pharmacological activity of EBN that could have potential application in the control of S. aureus.

• International Journal of Industrial Entomology and Biomaterials
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• v.17 no.1
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• pp.137-141
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• 2008

We previously isolated and cloned a cDNA of abaecin from the Bombus ignitus. In an effort to produce a large amount of soluble abaecin at low cost, we successfully expressed the peptide in Escherichia coli that are highly sensitive to its mature form. For this, we fused the peptide encoding 39 amino acids of mature B. ignitus abaecin to the thioredoxin gene together with a C-terminal 6xHis tag. An enterokinase cleavage site was introduced between the 6xHis tag and mature abaecin to allow final release of the recombinant peptide. A high yield of 9.6 mg soluble fusion protein from 200 ml of bacterial culture was purified by $Ni^{2+}$-charged His-Bind resin affinity column, and 1.4 mg of pure active recombinant abaecin was readily obtained by enterokinase cleavage, followed by affinity chromatograph. The molecular mass of recombinant abaecin peptide was determined by Tricin-SDS-PAGE analysis. The recombinant abaecin exhibited antibacterial activity against Gram-negative bacteria.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.650-655
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• 2011

Three new peptide analogs 5a-c were obtained through coupling of 5-Amino benzimidazoles 2a-c with L-phenylalanine. For the purpose ${\alpha}$-amino group was blocked with phthalic anhydride and activation of ${\alpha}$-carboxy group of phenylalanine was carried out by preparing phthaloyl-L-phenylalanyl chloride 4. After developing a successful peptide linkage, the phthaloyl group was removed by treating 5a-c with hydrazine hydrate to get free peptides 6a-c, purified through a column of Amberlite (IR-4B). All of these compounds 2a-c and 5,6a-c have been characterized on the basis of their IR, 1H NMR and EIMS analyses. Antibacterial activity of these compounds is also been reported.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1568-1576
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• 2021

Here, we conducted the study on the possibility of using FK-13, a short analog of human-derived antibacterial peptide LL-37, as a cosmetic preservative to discover a natural cosmetic preservative that is safe for human body. For the purpose, FK-13 composed of 13 amino acids was synthesized by solid-phase peptide synthesis, and purified using reversed phase-high performance liquid chromatography (RP-HPLC). The purity and molecular weight were confirmed by liquid chromatography-mass spectrometry (LC-MS) analysis. FK-13 showed high antimicrobial activity on the three gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, and Staphylococcus epidermidis), the three gram-negative bacteria (Escherichia coli, Salmonella typhimurium, and Pseudomonas aeruginosa), and also even the fungus Candida glabrata. FK-13 had a broad spectrum of antibacterial activity, showing a suitability as a cosmetic preservative. In addition, FK-13 showed high thermostability and higher antibacterial activity in a comparative test with existing natural herbal cosmetic and chemical preservatives. Therefore, as FK-13 is a safe material and has high antibacterial activity at a low concentration, it is likely to be applied as a peptide natural cosmetic preservative that can replace existing chemical preservatives.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2003.04a
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• pp.75-75
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• 2003

We have purified and characterized cecropin A-like antibacterial peptide from the hemolymph of immunized Galleria mellonella larvae. Acid extraction, gel filtration, preparative acid urea PAGE, and reversed-phase HPLC were used for purification of peptide. The molecular mass of the purified peptide was estimated to be 4160.68 Da by MALDI-TOF mass spectrometry. (omitted)

• 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.

• Proceedings of the Korean Biophysical Society Conference
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• 1999.06a
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• pp.32-32
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• 1999

Cecropin A(1-8)-magainin 2(1-12) and cecropm A(1-8)-melittin(1-12) hybrid peptides were known to have potent antitumor and antibacterial activity. In particular, cecropm A(l-8)-magainin 2(1-12) has powerful antibacterial and antitumor activity with no hemolytic effect.(omitted)

• Bulletin of the Korean Chemical Society
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• v.35 no.9
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• pp.2809-2812
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• 2014

The 43-residue defensin-like peptide coprisin, which is isolated from dung bettle, Copris tripartitus, is a potent antimicrobial peptide. In our previous work, we determined the tertiary structure of coprisin and found that alpha helical region of coprisin from residue 19 to residue 30 is important for its antimicrobial activities. Here, we designed cop12mer and cop9mer analogs of coprisin based on the tertiary structure of coprisin. To investigate the relationship between hydrophobicity and antimicrobial activities and develop the potent peptide antibiotics, we designed cop9mer-1 with substitution of $His^2$ with Trp in cop9mer. The results showed that cop9mer-1 has higher toxicities as well as improved antimicrobial activities compared to cop9mer. In order to reduce the toxicity of cop9mer-1, we designed cop9mer-2 and cop9mer-3 with substitution of $Cys^3$ with Lys or Ser. Substitution of $Cys^3$ with these hydrophilic amino acids results in lower cytotoxicities compared to cop9mer-1. Cop9mer-2 with substitution of $Cys^3$ with Lys in Cop9mer-1 showed high antibacterial activities against drug resistant bacteria without cytotoxicity. Antibiotic action of cop9mer-1 analog appears to involve permeabilization of the bacterial cell membrane while cop9mer-2 and cop9mer-3 may have different mechanism of action. These results imply that that optimum balance in hydrophobicity and hydrophilicity in these 9-meric peptides plays key roles in their antimicrobial activities as well as cytotoxicities.

• Journal of Life Science
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• v.26 no.3
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• pp.296-301
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• 2016

An antibacterial peptide from skin extract of the catfish Silurus asotus was purified and characterized. The acidified skin extract was put through a Sep-Pak C18 solid phase extraction cartridge using a stepwise gradient and divided into flow-through (F.T.), 10% methanol-elute (RM10), 60% methanolelute (RM60), and 100% methanol-elute (RM100) fractions. RM10, RM60, and RM 100 showed antimicrobial activity against Escherichia coli D31. On the other hand, the F.T. fraction did not show antimicrobial activity. Among the various fractions, RM 60 had the highest activity. RM 60 was partially purified on a cation exchange column (CM52) by a stepwise gradient. The ammonium acetate (pH 5.15) 0.02 M – 0.8 M fraction showed antimicrobial activity. Then an antimicrobial peptide was purified using a 0.6M fraction with strong antibacterial activity through a series of five C18 reversed-phase HPLC columns. For the characterization of the purified peptide, the molecular weight and amino acid sequence were analyzed by MALDI-TOF MS and Edman degradation. The molecular weight of this peptide was about 4182.1 [M+H]⁺. The amino acid sequence of this peptide was partially determined as follows: PALXXKARREAKVKF. These findings suggest that this peptide plays a significant role in the innate defense system of catfish skin.

• Journal of the Korean Magnetic Resonance Society
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• v.21 no.3
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• pp.78-84
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• 2017

Pseudin is a naturally occurring 24 amino-acid-residue antimicrobial peptide derived from the skin of paradoxical frog Pseud's paradoxa. It shows potency against the bacteria and antibiotic-resistant bacteria strain, but has high cytotoxicity against mammalian cell. In our previous study, substitution of $Pro^{11}$ for Gly (Ps-P) increased bacterial cell selectivity but decreased the antibacterial activity of pseudin. In this study, we designed pseudin analogue, Ps-4K-P with increased cationicity up to +7 in Ps-P by substituting Glu14, Gln10, Gln24, and Leu18 with Lys. Ps-4K-P showed improved potent antibacterial activity with high bacterial cell selectivity. We determined the tertiary structure of Ps-4K-P in the presence of DPC micelles by NMR spectroscopy and it has a hinge structure at $Pro^{11}$ followed by three turn helices from $Pro^{11}$ to $Val^{23}$ at the C-terminus. Amphipathicity with increased cationicity as well as helix-hinge-helix structural motif provided by introduction of a Pro at position $Gly^{11}$ are the crucial factors which confer antibacterial activity with bacterial cell selectivity to Ps-4K-P.