• Journal of Life Science
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• v.26 no.12
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• pp.1409-1414
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• 2016

In the larvae of the black soldier fly, Hermetia illucens, innate immunity mechanisms are activated in response to various pathogens and stimulants, resulting in the expression of antimicrobial peptides (AMPs). To induce the mass production of AMPs, H. illucens fifth instar larvae were immunized with five different kinds of bacteria. We isolated from the hemolymph of the H. illucens larvae after bacterial challenge, and their antimicrobial activities against Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli) were measured using the inhibition zone assay. Among these five different kinds of bacteria, the hemolymph of Bacillus subtilis-challenged H. illucens larvae showed the strongest antimicrobial activity against both Gram-positive bacteria and Gram-negative bacteria. The antimicrobial activity of the hemolymph of $1{\times}10^9cfu/ml$ B. subtilis-challenged H. illucens peaks at 24 hr at 48 hr post-infection and gradually declines with time. Moreover, the immunized hemolymph also showed strong antimicrobial activity against various poultry pathogens such as S. enteritidis, S. typhimurium, and S. pullorum. These results suggest that the expression of AMP genes in B. subtilis-challenged H. illucens is up-regulated by innate immune responses, and that B. subtilis-challenged H. illucens overexpressing AMPs may be useful as a feed additive in livestock diets to reduce the need for antibiotics.

• Journal of Veterinary Science
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• v.24 no.3
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• pp.44.1-44.17
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• 2023

Background: Antibiotic resistance is a significant public health concern around the globe. Antimicrobial peptides exhibit broad-spectrum and efficient antibacterial activity with an added advantage of low drug resistance. The higher water content and 3D network structure of the hydrogels are beneficial for maintaining antimicrobial peptide activity and help to prevent degradation. The antimicrobial peptide released from hydrogels also hasten the local wound healing by promoting epithelial tissue regeneration and granulation tissue formation. Objective: This study aimed at developing sodium alginate based hydrogel loaded with a novel antimicrobial peptide Chol-37(F34-R) and to investigate the characteristics in vitro and in vivo as an alternative antibacterial wound dressing to treat infectious wounds. Methods: Hydrogels were developed and optimized by varying the concentrations of crosslinkers and subjected to various characterization tests like cross-sectional morphology, swelling index, percent water contents, water retention ratio, drug release and antibacterial activity in vitro, and Pseudomonas aeruginosa infected wound mice model in vivo. Results: The results indicated that the hydrogel C proved superior in terms of cross-sectional morphology having uniformly sized interconnected pores, a good swelling index, with the capacity to retain a higher quantity of water. Furthermore, the optimized hydrogel has been found to exert a significant antimicrobial activity against bacteria and was also found to prevent bacterial infiltration into the wound site due to forming an impermeable barrier between the wound bed and external environment. The optimized hydrogel was found to significantly hasten skin regeneration in animal models when compared to other treatments in addition to strong inhibitory effect on the release of pro-inflammatory cytokines (interleukin-1β and tumor necrosis factor-α). Conclusions: Our results suggest that sodium alginate -based hydrogels loaded with Chol-37(F34-R) hold the potential to be used as an alternative to conventional antibiotics in treating infectious skin wounds.

• BMB Reports
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• v.32 no.6
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• pp.561-566
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• 1999

CA(1-8)-ME(1-12) [CA-ME], composed of cecropin A(1-8) and melittin(1-12), is a synthetic antimicrobial peptide having potent antibacterial and antitumor activities with minimal hemolytic activity. In order to investigate the effects of the flexible hinge sequence, Gly-Ile-Gly, of CA-ME on antibiotic activity, CA-ME and three analogues, CA-ME1, CA-ME2, and CA-ME3, were synthesized. The Gly-Ile-Gly sequence of Ca-ME was deleted in CA-ME1 and replaced with Pro and Gly-Pro-Gly in CA-ME2 and CA-ME3, respectively. CA-ME1 and CA-ME3 showed a significant decrease in antitumor activity and phospholipid vesicle-disrupting ability. However, CA-ME2 showed similar antitumor and vesicle-disrupting activities, as compared with CA-ME. These results suggest that the flexibility or ${\beta}$-turn induced by Gly-Ile-Gly or Pro in the central part of CA-ME may be important in the electrostatic interaction of the N-terminus cationic ${\alpha}$-helical region with the cell membrane surface and the hydrophobic interaction of the C-terminus amphipathic ${\alpha}$-helical region with the hydrophobic acyl chains in the cell membrane. CA-ME3 exhibited lower antitumor and vesicle-disrupting activities than CA-ME and CA-ME2. This result suggests that the excessive ${\beta}$-turn structure caused by the Gly-Pro-Gly sequence in CA-ME3 seems to interrupt ion channel/pore formation in the lipid bilayer. We concluded that the appropriate flexibility or bilayer. We concluded that the appropriate flexibility or ${\beta}$-turn structure provided by the central hinge is responsible for the effective antibiotic activity of the antimicrobial peptides with the helix-hinge-helix structure.

• Parasites, Hosts and Diseases
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• v.58 no.2
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• pp.173-179
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• 2020

Leishmaniasis is a prevalent cause of death and animal morbidity in underdeveloped countries of endemic area. However, there is few vaccine and effective drugs. Antimicrobial peptides are involved in the innate immune response in many organisms and are being developed as novel drugs against parasitic infections. In the present study, we synthesized a 5-amino acid peptide REDLK, which mutated the C-terminus of Pseudomonas exotoxin, to identify its effect on the Leishmania tarentolae. Promastigotes were incubated with different concentration of REDLK peptide, and the viability of parasite was assessed using MTT and Trypan blue dye. Morphologic damage of Leishmania was analyzed by light and electron microscopy. Cellular apoptosis was observed using the annexin V-FITC/PI apoptosis detection kit, mitochondrial membrane potential assay kit and flow cytometry. Our results showed that Leishmania tarentolae was susceptible to REDLK in a dose-dependent manner, disrupt the surface membrane integrity and caused parasite apoptosis. In our study, we demonstrated the leishmanicidal activity of an antimicrobial peptide REDLK from Pseudomonas aeruginosa against Leishmania tarentolae in vitro and present a foundation for further research of anti-leishmanial drugs.

• Journal of Veterinary Science
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• v.22 no.5
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• pp.59.1-59.13
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• 2021

Background: Antimicrobial peptides (AMPs) have been identified as promising compounds for consideration as novel antimicrobial agents. Objectives: This study analyzed the efficacy of cecropin B against Haemophilus parasuis isolates through scanning electron microscopy (SEM) and atomic force microscopy (AFM) experiments. Results: Cecropin B exhibited broad inhibition activity against 15 standard Haemophilus parasuis (HPS) strains and 5 of the clinical isolates had minimum inhibition concentrations (MICs) ranging from 2 to 16 ㎍/mL. Microelectrophoresis and hexadecane adsorption assays indicated that the more hydrophobic and the higher the isoelectric point (IEP) of the strain, the more sensitive it was to cecropin B. Through SEM, multiple blisters of various shapes and dents on the cell surface were observed. Protrusions and leakage were detected by AFM. Conclusions: Based on the results, cecropin B could inhibit HPS via a pore-forming mechanism by interacting with the cytoplasmic membrane of bacteria. Moreover, as cecropin B concentration increased, the bacteria membrane was more seriously damaged. Thus, cecropin B could be developed as an effective anti-HPS agent for use in clinical applications.

• Journal of Veterinary Science
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• v.25 no.1
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• pp.12.1-12.10
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• 2024

Background: Staphylococcus aureus and S. pseudintermedius are the major etiological agents of staphylococcal infections in humans, livestock, and companion animals. The misuse of antimicrobial drugs has led to the emergence of antimicrobial-resistant Staphylococcus spp., including methicillin-resistant S. aureus (MRSA) and methicillin-resistant S. pseudintermedius (MRSP). One novel therapeutic approach against MRSA and MRSP is a peptide nucleic acid (PNA) that can bind to the target nucleotide strands and block expression. Previously, two PNAs conjugated with cell-penetrating peptides (P-PNAs), antisense PNA (ASP)-cmk and ASP-deoD, targeting two essential genes in S. aureus, were constructed, and their antibacterial activities were analyzed. Objectives: This study analyzed the combined antibacterial effects of P-PNAs on S. aureus and S. pseudintermedius clinical isolates. Methods: S. aureus ATCC 29740 cells were treated simultaneously with serially diluted ASP-cmk and ASP-deoD, and the minimal inhibitory concentrations (MICs) were measured. The combined P-PNA mixture was then treated with S. aureus and S. pseudintermedius veterinary isolates at the determined MIC, and the antibacterial effect was examined. Results: The combined treatment of two P-PNAs showed higher antibacterial activity than the individual treatments. The MICs of two individual P-PNAs were 20 and 25 µM, whereas that of the combined treatment was 10 µM. The application of a combined treatment to clinical Staphylococcus spp. revealed S. aureus isolates to be resistant to P-PNAs and S. pseudintermedius isolates to be susceptible. Conclusions: These observations highlight the complexity of designing ASPs with high efficacy for potential applications in treating staphylococcal infections in humans and animals.

• Journal of the Korean Applied Science and Technology
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• v.34 no.2
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• pp.338-348
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• 2017

Protein hydrolysates derived from plants and animals having antioxidant, suppression of hypertension, immunodulatory, alleviation of pain, and antimicrobial activity has been known as playing important role like hormone. This study was performed to optimize the hydrolysis of protein of sea of cucumber by a flavourzyme. The ranges of processes were the reaction temperature of 40 to $60^{\circ}C$, pH 6 to 8, and enzyme concentration 0.5 to 1.5%(w/v). As a result, the optimization of process was determined at temperature of $48-50^{\circ}C$, pH of 7.0-7.2, and enzyme concentration of 1.0-1.1%(w/v), and degree of hydrolysis was 43-45 at above conditions. The molecular weight of hydrolysate was distributed to 500-3,500 Da and showed typical peptides. Inhibition concentration ($IC_{50}$) of peptides of DPPH radical scavenging activity, Superoxide anion radical scavenging activity, Hydroxy radical scavenging activity, $Fe^{2+}$ cheating activity was 1.25, 3.40, 10.3, and 22.11 mg/mL, respectively. Therefore, we expect that those products are useful as functional food ingredients.

• Journal of the Korean Applied Science and Technology
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• v.34 no.3
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• pp.631-642
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• 2017

Protein hydrolysates derived from plants and animals having antioxidant, suppression of hypertension, immunodulatory, alleviation of pain, and antimicrobial activity has been known as playing important role like hormone. This study was performed to hydrolysis of Ogae egg white protein using the six proteases. The antioxidant activity of the produced peptides was analyzed. As a result, the maximum value of hydrolysis was protamex(46.3%), DPPH radical scavenging was bromelain(57.23%), hydroxy radical scavenging was alcalase(30.21%), superoxide radical scavenging was alcalase(58.07%), and $Fe^{2+}$ chelation ability was alcalase(72.06%). Furthermore, the antioxidant Inhibition concentration ($IC_{50}$) of peptides was evaluated for each enzyme. As a result, the maximum value of alcalase was $Fe^{2+}$ cheating ability($IC_{50}$, 1.24 mg/mL), bromelain was DPPH radical scavenging($IC_{50}$, 2.46 mg/mL), flavourzyme was $Fe^{2+}$ cheating ability($IC_{50}$, 1.25 mg/mL), neutrase was DPPH radical scavenging($IC_{50}$, 3.64 mg/mL), papain was DPPH radical scavenging ($IC_{50}$, 3.82 mg/mL) and protamex was DPPH radical scavenging($IC_{50}$, 1.93 mg/mL). Therefore, we expect that peptides produced from Ogae egg white protein using protease enzyme are useful as an antioxidant functional food ingredients.

• Journal of the Korean Applied Science and Technology
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• v.34 no.3
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• pp.673-682
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• 2017

Protein hydrolysates derived from plants and animals having antioxidant, suppression of hypertension, immunodulatory, alleviation of pain, and antimicrobial activity has been known as playing important role like hormone. This study was fractioned to hydrolysis of Ogae egg white protein using the ultrafiltration. The antioxidant activity of the produced peptides was analyzed. As a result, the maximum value of DPPH radical scavenging was 1 kDa(70.83 %), hydroxy radical scavenging was 5 kDa(47.01 %), superoxide anion radical scavenging was 5 kDa(40.57 %), and $Fe^{2+}$ chelation ability was 5 kDa(29.87 %). Furthermore, the antioxidant Inhibition concentration ($IC_{50}$) of peptides was evaluated for each fraction. As a result, the maximum value of HDS was superoxide anion radical scavenging($IC_{50}$, 5.42 mg/ml). 1 kDa was $Fe^{2+}$ chelation ability($IC_{50}$, 1.67 mg/ml), 5 kDa was $Fe^{2+}$ cheating ability($IC_{50}$, 2.09 mg/ml), 10 kDa was $Fe^{2+}$ cheating ability($IC_{50}$, 2.61 mg/ml), papain was $Fe^{2+}$ cheating ability($IC_{50}$, 4.53 mg/ml). Therefore, we expect that peptides produced from Ogae egg white protein using 5 kDa fraction are useful as an antioxidant functional food ingredients.

• Journal of Periodontal and Implant Science
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• v.43 no.1
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• pp.3-11
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• 2013

Periodontitis is a chronic inflammation of periodontal tissue caused by subgingival plaque-associated bacteria. Periodontitis has long been understood to be the result of an excessive host response to plaque bacteria. In addition, periodontal pathogens have been regarded as the causative agents that induce a hyperinflammatory response from the host. In this brief review, host-microbe interaction of nonperiodontopathic versus periodontopathic bacteria with innate immune components encountered in the gingival sulcus will be described. In particular, we will describe the susceptibility of these microbes to antimicrobial peptides (AMPs) and phagocytosis by neutrophils, the induction of tissue-destructive mediators from neutrophils, the induction of AMPs and interleukin (IL)-8 from gingival epithelial cells, and the pattern recognition receptors that mediate the regulation of AMPs and IL-8 in gingival epithelial cells. This review indicates that true periodontal pathogens are poor activators/suppressors of a host immune response, and they evade host defense mechanisms.