• Bulletin of the Korean Chemical Society
• /
• v.18 no.1
• /
• pp.50-56
• /
• 1997

The mode of action of mastoparan B, an antimicrobial cationic tetradecapeptide amide isolated from the hornet Vespa basalis, toward phospholipid bilayers was studied with synthetic mastoparan B and its analogs with individual Ala instead of hydrophobic amino acids (1-Ile, 3-Leu, 6-Leu, 7-Val, 9-Trp, 13-Val, 14-Leu) in mastoparan B. Mastoparan B and its analogs were synthesized by the solid-phase method. Circular dichroism spectra showed that mastoparan B and its analogs adopted an unordered structure in buffer solution. In the presence of neutral and acidic liposomes, most of the peptides took an α-helical structure. The calcein leakage experiment indicated that mastoparan B interacted strongly with neutral and acidic lipid bilayers than its analogs. Mastoparan B also showed a more or less highly antimicrobial activity and hemolytic activity for human erythrocytes than its analogs. These results indicate that the hydrophobic face in the amphipathic α-helix of mastoparan B critically affect biological activity and helical contents.

• Microbiology and Biotechnology Letters
• /
• v.38 no.2
• /
• pp.190-197
• /
• 2010

To develop the safe and natural antimicrobial agents, the 68 ethanol extracts from the 61 different kinds of oriental herbal medicine were prepared and their antimicrobial activities were evaluated. The herbal medicine used were from China (46 kinds), South Korea (14 kinds), North Korea (5 kinds) and Vietnam (3 kinds), respectively, and the root (27 species) was popular part in this study. The average water content and extraction ratio for ethanol were 7.10% and 6.75%, respectively. Determination of antimicrobial activity by disc-diffusion assay at 0.5 mg/disc concentration showed that the extract of Angelica tenuissima Nakai (china), Illicium verum, Junci medulla, Rhus javanica L., Salvia miltiorrhiza Bunge and Syzygium aromaticum has strong antimicrobial activities against different food spoilage and pathogenic bacteria and fungi. Determination of MIC and MBC/MFC further showed that the extract of Syzygium aromaticum has MIC of 1.25 mg/mL and MBC/MFC of 1.25~5.00 mg/mL against Listeria monocytogenes, Bacillus subtilis, Staphylococcus epidermidis, Staphylococcus aureus, Salmonella typhimurium, Proteus vulgaris, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Saccharomyces cerevisiae. And, the extract of Junci medulla, Rhus javanica L. and Salvia miltiorrhiza Bunge showed strong antibacterial activities with MIC of 0.08~0.63 mg/mL and MBC/MFC of 0.08~2.50 mg/mL against the tested bacteria except E. coli and P. aeruginosa. In a while, the results of hemolytic activity of 68 different herbal extracts against human red blood cells showed that the extract of Angelica tenuissima Nakai has hemolytic activity at 0.5 mg/mL concentration. Therefore, Illicium verum, Junci medulla, Rhus javanica L., Salvia miltiorrhiza Bunge and Syzygium aromaticum were finally selected for natural antimicrobial resources. Further research on active substances and the mode of action of the selected herbal medicine is necessary.

• The Korean Journal of Mycology
• /
• v.18 no.2
• /
• pp.58-69
• /
• 1990

ABSTRACT: In order to find physiologically active components from higher fungi, hot-water soluble components were extracted from the basidiocarps of Ganoderma lucidum. The extract was purified and separated by DEAE cellulose ion exchange chromatography and Sepharose CL-4B gel filtration method. The separated fractions were designated CR, IN, IA, GL and GH. Fraction GL showed the highest antitumor activity among the fractions and its molecular weight was found to be 47 KD. The tumor inhibition ratio of Fr. GL was 81 % at the dose of peritoneal administration of 20 mg/kg/day for 10 days in mice. Chemical analysis of this fraction showed 82% polysaccharide, 8% protein and 0.9% hexosamine. The polysaccharide moiety consisted of 63% glucose, 27% galactose, 7% mannose and 3% fucose. Fraction IN was found to increase the amount of superoxide anion in activated macrophages to 1.6-fold and the number of plaques in hemolytic plaque assay to 6-fold, respectively. These results indicate that the antitumor activity was exerted through immunopotentiation, but not through direct cytotoxicity against the tumor.

• The Korean Journal of Mycology
• /
• v.20 no.3
• /
• pp.240-251
• /
• 1992

To find antitumor components from higher fungi, the cultured mycelia of Paxillus atrotomentosus were extracted with hot water. The water soluble fraction was purified and separated by DEAE-cellulose ion exchange chromatography and Sepharose CL-4B gel filtration method. The separated fractions(Fr.) were designated CR A, B, C and D. Fr. A showed the highest inhibition ratio of 68.51% among the five tractions at a dose of 20 mg/kg/day. When Fr. A was examined for immunopotentiation activity, it increased the amount of the superoxide anion from activated macrophages to 1.1 fold and the number of plaques in hemolytic plaque assay to 2.3 fold, respectively. Otherwise, it did not show direct cytotoxity in sarcoma 180. Delayed type hypersensitiyity reaction showed that the decreased footpad swelling of tumor-hearing was restored to the normal. These results indicate that antitumor activity was exerted through immunopotentiation. Its chemical analysis showed 86.36% polysaccharide, 1.52% protein and 1.64% hexosamine. The polysaccharide consisted of fucose, galactose, glucose, mannose and xylose. This component was named paxillan.

• Journal of Applied Biological Chemistry
• /
• v.61 no.3
• /
• pp.213-217
• /
• 2018

Tolaasin secreted by Pseudomonas tolaasii is a peptide toxin and causes brown blotch disease on the cultivated mushrooms by collapsing cellular and fruiting body structure. Toxicity of tolaasin was evaluated by measuring hemolytic activity because tolaasin molecules form membrane pores on the red blood cells and destroy cell membrane structure. In the previous studies, we found that tolaasin cytotoxicity was suppressed by $Zn^{2+}$ and $Ni^{2+}$. $Ni^{2+}$ inhibited the tolaasin-induced hemolysis in a dose-dependent manner and its $K_i$ value was 1.8 mM. The hemolytic activity was completely inhibited at the concentration higher than 10 mM. The inhibitory effect of $Zn^{2+}$ on tolaasin-induced hemolysis was increased in alkaline pH, while that of $Ni^{2+}$was not much dependent on pH. When the pH of buffer solution was increased from pH 7 to pH 9, the time for 50% hemolysis ($T_{50}$) was increased greatly by $100{\mu}M$ $Zn^{2+}$; however, it was slightly increased by 1 mM $Ni^{2+}$ at all pH values. When the synergistic effect of $Zn^{2+}$ and $Ni^{2+}$ on tolaasin-induced hemolysis was measured, it was not dependent on the pH of buffer solution. Molecular elucidation of the difference in pH-dependence of these two metal ions may contribute to understand the mechanism of tolaasin pore formation and cytotoxicity.

• Microbiology and Biotechnology Letters
• /
• v.50 no.2
• /
• pp.283-292
• /
• 2022

Colibactins (clb) and Cytotoxic Necrotizing Factors (cnf) are virulence factors that impact cell cycle through cellular differentiation, proliferation, and apoptosis. Urinary tract infections (UTIs) are the most common among type of infection among outpatients, with a lifetime incidence of about 60-65% in adult females. Here, we sought to isolate uropathogenic Escherichia coli (UPCE) from urine specimens and investigates the prevalence of clb A, B and cnf 1, 2 genes among these isolates. A total of 110 E. coli isolates were collected from patients with UTIs. All the isolates were examined for their hemolytic activity and only 46 isolates showed a halo zone of hemolysis on blood agar. The collected UPEC isolates were screened for the existence of clb A, B and cnf genes. The results revealed that out of 110 isolates, 28 harbored the clbA gene, 40 harbored clb B, and 24 isolates harboured cnf1. 13 isolates harbored clbA, clbB, and cnf1 genes, while no cnf2 gene was detected among isolates. The molecular detection revealed that 8 out of 28 hemolytic isolates carrying the clbA, 11 out of 40 were carrying clbB, 1 out of 24 were carrying cnf 1, and 5 out of 9 carrying clbA+clbB. Furthermore, 7 out of 13 isolates were hemolytic and carrying clbA, clbB, and cnf1 genes. Finally, we investigated the cytotoxicity of E. coli harboring clb and cnf genes, eukaryotic REF cells were exposed to E. coli producing colibactin, which induces DNA damage and leads to cell cycle arrest, senescence and death.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.8
• /
• pp.2577-2583
• /
• 2011

We have designed a 20-residue hybrid peptide CA(1-8)-MA(1-12) (CAMA) incorporating residues 1-8 of cecropin A (CA) and residues 1-12 of magainin 2 (MA) with high bacterial cell selectivity. CAMA-P2 is an ${\alpha}$-helical antimicrobial peptide designed from a CAMA hybrid peptide and substitution of Gly-Ile-Gly hinge sequence of CAMA to Pro influences the flexibility at central part of CAMA. Based on structure-activity relationships of CAMA peptides, to investigate the effects of the total positive charges on antimicrobial activity of CAMA-P2, the $Ser^{14}{\rightarrow}$Lys analogue (CAMA-syn1) was synthesized. The role of tryptophan at C-terminal ${\alpha}$-helix on its antimicrobial activity as well as synergistic activity was also investigated using $Ser^{14}{\rightarrow}$Lys/$Phe^{18}{\rightarrow}$Trp analogue (CAMA-syn2). Also, we designed CAMA-syn3 by substitution of $Lys^{16}$ located opposite side of substituted $Lys^{14}$ of CAMA-syn1 with Leu residue, resulting in increase of hydrophobicity and amphipathicity of the peptide. All of CAMA-syn analogues showed good antimicrobial activities similar to those of CAMA and CAMA-P2. The CAMA-syn1 and CAMA-syn2 showed low hemolytic activity and cytotoxicity against human keratinocyte Haca-T cells while CAMA-syn3 showed hemolytic activity and cytotoxicity at its MIC value. We then investigated their abilities to act synergistically in combination with the antimicrobial flavonoids and synthetic compounds screened in our laboratory. The results showed that all peptides exhibited synergistic effects with dihydrobinetin, while only CAMA-syn2 exhibited synergistic effects with YKAs3001 against both S. aureus and MRSA, suggesting that Trp residue at C-terminus of CAMA-syn2 may facilitate the polar antibiotic flavonoids and synthetic compounds to permeabilize the membrane. This study will be useful for the development of new antibiotic peptides with potent antimicrobial and synergistic activity but without cytotoxicity.

• Korean Journal of Pharmacognosy
• /
• v.12 no.2
• /
• pp.88-93
• /
• 1981

One hundred and forty-four extracts have been tested for the presence of saponins, using the method of froth formation, precipitate formation by acid hydrolysis, Liebermann-Buchard reaction on the acid hydrolysate, and hemolytic activity of the extracts. Among the samples tested, thirteen extracts showed positive saponin reaction in all the tests employed and one hundred and thirty-six showed positive in one or more tests of saponins. The results are tabulated.

• YAKHAK HOEJI
• /
• v.31 no.2
• /
• pp.70-81
• /
• 1987

To elucidate action mechanism of lyophyllan A, an antitumor polysaccharide of Lyophyllum decastes, its immunological activities were examined. Lyophyllan A increased significantly the weights of spleen and liver of mice. Lyophyllan A also restored the decreased thymic weight in tumor-bearing mice. It did not show any direct cytotoxicity against tumor cells, but showed immunopotentiating activities by increasing the number of the plaques in hemolytic plaque assays. Lyophyllan A increased the number of peritoneal exudate cells (PEC) and inhibited the growth of sarcoma 180 mixed with PEC. Moreover the macrophages from lyophyllan A-treated mice exhibited a strong cytotoxic activity towards L5178Y target cells.

• Proceedings of the Korean Biophysical Society Conference
• /
• 1997.07a
• /
• pp.13-13
• /
• 1997

Gaegurin 4 is an antimicrobial peptide found in the skin of a Korean frog, Rana rugosa, known for its "wound-healing" effect for years. This 37-residue basic peptide binds to cell membranes and forms ion channels like other antimicrobial peptides but does not exhibit hemolytic activity.(omitted)