• Asian-Australasian Journal of Animal Sciences
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• v.28 no.9
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• pp.1354-1361
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• 2015

The complement system is a part of the natural immune regulation mechanism against invading pathogens. Complement activation from three different pathways (classical, lectin, and alternative) leads to the formation of C5-convertase, an enzyme for cleavage of C5 into C5a and C5b, followed by C6, C7, C8, and C9 in membrane attack complex. The C9 is the last complement component of the terminal lytic pathway, which plays an important role in lysis of the target cells depending on its self-polymerization to form transmembrane channels. To address the association of C9 with traits related to disease resistance, the complete porcine C9 cDNA was comparatively sequenced to detect single nucleotide polymorphisms (SNPs) in pigs of the breeds Hampshire (HS), Duroc (DU), Berlin miniature pig (BMP), German Landrace (LR), Pietrain (PIE), and Muong Khuong (Vietnamese potbelly pig). Genotyping was performed in 417 $F_2$ animals of a resource population (DUMI: $DU{\times}BMP$) that were vaccinated with Mycoplasma hyopneumoniae, Aujeszky diseases virus and porcine respiratory and reproductive syndrome virus at 6, 14 and 16 weeks of age, respectively. Two SNPs were detected within the third exon. One of them has an amino acid substitution. The European porcine breeds (LR and PIE) show higher allele frequency of these SNPs than Vietnamese porcine breed (MK). Association of the substitution SNP with hemolytic complement activity indicated statistically significant differences between genotypes in the classical pathway but not in the alternative pathway. The interactions between eight time points of measurement of complement activity before and after vaccinations and genotypes were significantly different. The difference in hemolytic complement activity in the both pathways depends on genotype, kind of vaccine, age and the interaction to the other complement components. These results promote the porcine C9 (pC9) as a candidate gene to improve general animal health in the future.

• Journal of Microbiology
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• v.35 no.1
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• pp.21-24
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• 1997

The hybrid peptides, CA-ME, CA-MA and CA-BO, with the N-terminal sequence 1-8 of cecropin A and the N-terminal sequences 1-12 of melittin, magainin 2 and bombinin, respectively, have more improved antibacterial activities. CA-MA was found to have stronger antifungal activity against Trichoderma sp than other hybrid peptides and their parental peptides. In order to elucidate the relationships between the peptide structure and antifungal activity, several analogues of CA-MA or CA-BO were also designed and synthesized by the solid phase method. An tifungal activity was measured against T. reesei and T. viride, and hemolytic activity was measured by a solution method against human red blood cells. The residue 16 of CA-MA, Ser, was found to be important for antifungal activity. When the residue was substituted with Leu, showed powerful antifungal activity was dramatically decreased. CA-MA, P1, P4 and P5 designed in this study showed powerful antifungal activity against T. reesei and T. viride with low hemolytic activity against human red blood cells. These hybrid peptides will be potentially useful model to further design peptides with powerful antifungal activity for the effective therepy of fungal infection and understand the mechanisms of antifungal actions of hybrid peptides.

• Environmental Mutagens and Carcinogens
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• v.26 no.2
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• pp.41-44
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• 2006

This study was peformed to determine the antioxidant, antimicrobial activity and antifungal of the cambodian mushroom, Phellinus linteus, in various concentrations from the mushroom extracts. It's extracts were found to cause significant free radical scavenging effects on DPPH (1,1-diphenyl-2-picrylhydrazyl). This extracts exhibited in vitro broad-spectrum antimicrobial activity of Gram-negative, Gram-positive bacteria and without antifungal activity. On the other hand, the extracts had not significant hemolytic activity against human red blood cells. These results indicate cambodian mushroom, Phellinus inteus having antioxidant and antimicrobial activity without hemolytic activity maybe useful as therapeutic agents.

• Bulletin of the Korean Chemical Society
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• v.20 no.9
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• pp.1073-1077
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• 1999

CRAMP, a 37-amino acid cationic antimicrobial peptide was recently deduced from the cDNA cloned from mouse femoral marrow RNA. In order to investigate the structure-activity relationship and functional region of CRAMP, CRAMP and its 18-mer overlapping peptides were synthesized by the solid phase method. CRAMP showed broad spectrum antibacterial activity against both Gram-positive and Gram-negative bacterial strains (MIC: 3.125-6.25 μM) but had no hemolytic activity until 50 μM. CRAMP was found to have a potent anticancer activity (IC50: 12-23 μM) against two human small cell lung cancer cell lines. Furthermore, CRAMP was found to display faster bactericidal rate in B. subtilis rather than E. coli in the kinetics of bacterial killing. Among 18-meric overlapping fragment peptides, only CRAMP (16-33) displayed potent antibacterial activity (MIC: 12.5-50 μM) against several bacteria with no hemolytic activity. Circular dichroism (CD) spectra anal-ysis indicated that CRAMP and its analogues will form the amphipathic α-helical conformation in the cell membranes similar to other antimicrobial peptides, such as cecropins and magainins.

• Microbiology and Biotechnology Letters
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• v.52 no.2
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• pp.179-188
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• 2024

It has been widely documented that stress conditions in aquatic ecosystems could trigger the release of stress hormone (dopamine) in fishes. Such hormone could attract pathogens (such as Aeromonas hydrophila) to initiate its infection in fishes. The major focus of this study was to investigate the effect of the catecholamine derived stress hormone (dopamine) on the motility and hemolytic activity associated with the virulence of A. hydrophila ATCC AH-1N, the causative agent of Motile Aeromonas Septicemia (MAS). The density of bacterial cells used in this study was adjusted at 106 cells/ml. The results showed that dopamine increased swimming motility of A. hydrophila ATCC AH-1N and was proportional to both dopamine hormone concentration and the incubation period. Dopamine concentration of 100 µM in the medium resulted in the highest increment of swimming ability of A. hydrophila ATCC AH-1N. The dopamine hormone was also found to affect the hemolytic activity of A. hydrophila ATCC AH-1N. The optimum hemolytic activity of the pathogen was found at 50 µM dopamine concentration in the medium, and this hemolytic activity was found to decrease when the concentration of dopamine at greater than 50 µM. It can be concluded from this study that dopamine hormone increased the motility and hemolysis capability, as well as the growth rate of A. hydrophila, and hence increased its virulence.

• Bulletin of the Korean Chemical Society
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• v.35 no.12
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• pp.3632-3636
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• 2014

In this study we designed and synthesized several heptapeptides that are enforced to form an amphipathic helix using all-hydrocarbon stapling system and evaluated their antimicrobial and hemolytic activities. The antimicrobial activity showed clear structure-activity relationships, confirming the importance of helicity and amphipathicity. Some stapled heptapeptides displayed a moderate antimicrobial activity along with a low hemolytic activity. To our best knowledge, although not highly potent, these stapled peptides represent the shortest helical amphipathic antimicrobial peptides reported to date. The preliminary data obtained in this work would serve as a good starting point for further developing short analogs of amphipathic helical antimicrobial peptides.

• Microbiology and Biotechnology Letters
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• v.43 no.1
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• pp.84-90
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• 2015

Seventeen ampicillin-sensitive coagulase-negative staphylococci (CNS) isolates identified in jeotgal were subjected to assessments for antibiotic susceptibility and safety hazards. Fifteen of the 17 CNS strains exhibited phenotypic resistances to at least one antibiotic, and their prevailing resistance was to penicillin G. The dfrA gene for trimethoprim and tetK for tetracycline were amplified by PCR from the two strains, respectively. α-Hemolytic activity was not detected from the 17 strains, while five strains presented δ-hemolytic activity. Among the five strains, two strains exhibited β-hemolytic activity. Biofilm was formed from twelve strains. All of the tested phenotypic characteristics were expressed in a strain-specific manner.

• Journal of the Korean Applied Science and Technology
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• v.31 no.1
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• pp.130-135
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• 2014

To develop a natural antioxidant and anti-hemolytic agents, we investigated the effects of ethanol extracts of Rubus coreanus Miquel (crude extracts). Crude extract was extracted with ethanol. Antioxidant activity of crude extracts was evaluated by employing two different assays, 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity and super oxide dismutase(SOD)-like activity. Also, anti-hemolytic activity of crude extract was determined using $H_2O_2$-induced hemolysis in normal rat red blood cells (RBC) or plasma. The extracts obtained from crude extract dose-dependently increased the scavenging activity on DPPH-induced radicals and SOD-like activity. RBC oxidative hemolysis induced by $H_2O_2$ was significantly suppressed by the extracts of Rubus coreanus Miquel in a dose-dependent manner. These results suggest that crude extracts may have value as the potential antioxidant and anti-hemolytic medicinal plant.

• The Journal of the Korean Society for Microbiology
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• v.22 no.1
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• pp.23-33
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• 1987

To detect lepotospiral strains which produce hemolysin and determine the optimal condition for assaying hemolysin, we screened reference strains and observed some property of hemolysin. Hemolysin activity was assayed with cell free culture liquids and erythrocyte suspension. The production of hemolysin by local strains isolated in Korea was assayed and compared with that of reference strains. The hemolysin was produced by 18 strains among 38 reference strains and 3 local strains isolated in Korea. The production of hemolysin began with growth of Leptospira cultured in EMJH medium and reached maximum at stationary phase. The optimum temperature for hemolytic activity was $37^{\circ}C$. At lower temperature the activity of hemolysin was decreased progressively. The hemolytic activity was completely inactivated after :30 minutes' exposure at $56^{\circ}C$. Hemolysis pattern was "hot-cold type" which showed increased hemolysis after cold incubation. The hemolysin was most active on sheep erythrocyte and less active on ox, goat, human and guinea pig erythrocyte with the decreasing order.

• Journal of Microbiology and Biotechnology
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• v.7 no.1
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• pp.49-51
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• 1997

In order to obtain a hybrid synthetic peptide with a more potent antifungal activity than magainin-2 but without hemolytic activity, four hybrid peptides were designed from the sequences of magainin 2 and cecropin A and their antifungal activities against Trichosporon beigelii were investigated. The result showed that analogue 2 and 4 exhibited better antifungal activity against T. beigelii than magainin-2 but no hemolytic activities. The peptides, therefore, could be used as models for the development of potent antifungal peptides.