• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.121-127
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• 2004

Amphotericin B (AmB), an amphipathic polyene macrolide, is an antifungal drug produced by Streptomyces nodosus. Recently, AmB has been shown to exert antiviral activity against rubella virus and human immunodeficiency virus by different mechanisms. In this study, we evaluated the antiviral effect of AmB against Japanese encephalitis virus (JEV) and investigated which step of the viral life cycle was inhibited by AmB to understand the mechanism of antiviral action of AmB. AmB reduced both plaque size and number in the infected cells in a dose-dependent manner. In addition, a 200-fold reduction of infectious virus titer was observed by treatment of infected cells with $5\mug/ml$ of AmB. AmB acted at the post virus-infection step, but not during adsorption of virus to host cells. Western blot analysis revealed that the accumulated level of JEV envelope protein dramatically decreased in the infected cells by treatment with $5-10\mug/ml$ of AmB. Our results indicate that AmB inhibits the replication of JEV at the postinfection step by interfering with viral replication and/or by inhibiting the synthesis of viral proteins.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.88-89
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• 2000

Chitosan is derived from chitin by deacetylation in the presence of alkali, which is a copolymer consisting of $\beta$-(1longrightarrow4)-2-acetamido-D-glucose and $\beta$-(1longrightarrow4)-2-amino-D-glucose units with the latter usually exceeding 80% (Arvanitoyannis et al., 1998). Chitosan has been developed as new physiological material since it possesses antibacterial activity, hypocholesterolemic activity and antihypertensive action. However, even though chitosan has very strong functional properties in many areas, its high molecular weight and high viscosity may restrict the use in vivo. In addition, there is little doubt that such properties will influence absorption in the human intestine. Recently, studies on chitosan have attracted interest for converted chitosan to oligosaccharide, because the oligosaccharide possesses not only water-soluble property but also versatile functional properties such as antitumor activity, immune-enhancing effects, enhancement of protective effects against infection with some pathogens in mice, antifungal activity, calcium absorption accelerating effect (Jeon et al., 1999) and antimicrobial activity. There is, however, little information on the toxicity of chitosan oligosaccharide. (omitted)

• The Korean Journal of Pesticide Science
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• v.7 no.2
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• pp.155-158
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• 2003

2-Imino-1,3-thiazolines 1 show selective antifungal activity against pyricularia oryzae by new mode of action. A synthesis of novel 2-cyano-l,3-thiazolines 2 in which cyano moiety is substituted in imino group at C-2 of 1 is described. The lone pair electrons of sulfur and nitrogen as well as strong electron withdrawing cyano substituent in 1,3-thiazoline scaffold would effect the biological activity of 2-imino-1,3-thiazoline series. Regiospecific nucleophilic attack of thiourea 4 for $\gamma$-chloro-$\beta$-ketoacetoacetanilide 3 followed by acid catalyzed dehydration gave 2.

• Mycobiology
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• v.46 no.1
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• pp.33-46
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• 2018

Gray mold (Botrytis cinerea) is one of the most common diseases of strawberries (Fragaria${\times}$ananassa Duchesne) worldwide. Although many chemical fungicides are used for controlling the growth of B. cinerea, the risk of the fungus developing chemical resistance together with consumer demand for reducing the use of chemical fungicides have necessitated an alternative method to control this pathogen. Various naturally occurring microbes aggressively attack plant pathogens and benefit plants by suppressing diseases; these microbes are referred to as biocontrol agents. However, screening of potent biocontrol agents is essential for their further development and commercialization. In this study, 24 strains of yeast with antagonistic ability against gray mold were isolated, and the antifungal activity of the volatile and diffusible metabolites was evaluated. Putative mechanisms of action associated with the biocontrol capacity of yeast strains against B. cinerea were studied through in vitro and in vivo assays. The volatile organic compounds produced by the Galactomyces candidum JYC1146 could be useful in the biological control of plant pathogens and therefore are potential alternative fungicides with low environmental impact.

• Journal of Microbiology
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• v.33 no.4
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• pp.295-301
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• 1995

An antifungal Pseudomonas stutzeri YPL-1 produced extracellular chitinase and .betha.-1, 3-glucanase that were key enzymes in the decomposition of fungal hyphal walls. These lytic extracellular enzymes markedly inhibited mycelial growth of the phytopathogenic fungus Fusarium solani. A chitinase from P. stutzeri YPL-1 inhibited fungal mycelial growth by 87%, whereas a .betha.-1, 3-glucanase from the bacterium inhibited growth by 53%. Furthermore, co-operative action of the enzymes synergistically inhibited 95% of the fungal growth. The lytic enzymes caused absnormal swelling and retreating on the fungal hyphal walls in a dual cultures. Scanning electron microscopy clearly showed hyphal degradation of F. solani in the regions interacting with P. stutzeri YPL-1. In an in vivo pot test, P. stutzeri YPL-1 proved to have biocontrol ability as a powerful agent in controlling plant disease. Planting of kidney bean (Phaseolus vulgaris L.) seedlings with the bacterial suspension in F. solani-infested soil significantly suppressed the development of fusarial root-rot. The characteristics of a crude preparation of .betha.-1, 3-glucanase produced from P. stutzeri YPL-1 were investigated. The bacterium detected after 2 hr of incubation. The enzyme had optimum temperature and pH of 40.deg.C and pH 5.5, respectively. The enzyme was stable in the pH range of 4.5 to 7.0 and at temperatures below 40.deg.C, with a half-life of 40 min at 60.deg.C.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.990-996
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• 2008

In a previous study, we found an antifungal effect on human pathogenic fungi by the cell-penetrating peptide Tat (47-58) derived from HIV-1. Tat (47-58) immediately entered into the fungal nucleus and affected some physiological changes on the intracellular condition. In this study, Tat (47-58) showed a broad spectrum of antibacterial activity against pathogenic bacteria including bacterial clinical isolates. To improve resistance against proteases for use in vivo, we synthesized an analog of Tat (47-58) by substituting the L-amino acid for the D-amino acid. The D-enantiomer of Tat (47-58) also exhibited a broad spectrum of antibacterial activity at almost the same level of L-Tat (47-58) concentration. Unlike L-Tat (47-58), D-Tat (47-58) showed a significant proteolytic resistance against all proteases tested and antimicrobial activities in the presence of trypsin. Moreover, D-Tat (47-58) inhibited MRSA infection in human HeLa cells whereas L-Tat (47-58) partially allowed MRSA infection, and the results were due to the proteolytic resistance of D-Tat (47-58).

• Journal of Microbiology and Biotechnology
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• v.30 no.12
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• pp.1827-1834
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• 2020

Candida albicans is a major fungal pathogen in humans. In our previous study, we reported that an ethanol extract from Aucklandia lappa weakens C. albicans cell wall by inhibiting synthesis or assembly of both (1,3)-β-D-glucan polymers and chitin. In the current study, we found that the extract is involved in permeabilization of C. albicans cell membranes. While uptake of ethidium bromide (EtBr) was 3.0% in control cells, it increased to 7.4% for 30 min in the presence of the A. lappa ethanol extract at its minimal inhibitory concentration (MIC), 0.78 mg/ml, compared to uptake by heat-killed cells. Besides, leakage of DNA and proteins was observed in A. lappa-treated C. albicans cells. The increased uptake of EtBr and leakage of cellular materials suggest that A. lappa ethanol extract induced functional changes in C. albicans cell membranes. Incorporation of diphenylhexatriene (DPH) into membranes in the A. lappa-treated C. albicans cells at its MIC decreased to 84.8%, after 60 min of incubation, compared with that of the controls, indicate that there was a change in membrane dynamics. Moreover, the anticandidal effect of the A. lappa ethanol extract was enhanced at a growth temperature of 40℃ compared to that at 35℃. The above data suggest that the antifungal activity of the A. lappa ethanol extract against C. albicans is associated with synergistic action of membrane permeabilization due to changes in membrane dynamics and cell wall damage caused by reduced formation of (1,3)-β-D-glucan and chitin.

• The Korean Journal of Pesticide Science
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• v.19 no.4
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• pp.402-410
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• 2015

The purpose of this study was to estimate the chitinolytic and antifungal activity of Actinomycetes sp.isolated from waste mushroom media. In five kinds of waste mushroom media, Sinyeong mushroom and Yangsongi were the order of the population density of actinomycetes. Totally 91 chitinolytic isolates of Actinomycetes sp. were obtained from waste mushroom media. The isolates were categorized into 3 groups based on chitinolytic activity and antagonisms against Phytophthora capsici, Rhizoctonia solani, Sclerotinia sclerotiorum, Collectotrichum gloeosporioides, and Cladosporium cucumerinum in vitro. CA-23 was selected as a representative isolate of a group showing strong chitinolytic and antagonistic activities to all of the plant pathogens, while AA-65 was selected as a representative isolate showing no chitinolytic activities but strong antagonistic activities to the pathogens. CA-23 and AA-65 were highly effective on control of Phytophthora blight of hot-pepper, powdery mildew and scab of cucumber in a greenhouse tests. Among the isolates tested, CA-23 showed highest control efficacy, while AA-65 not only effectively controlled the diseases but also consistently increased plant growth and yield. Although the isolates are similarly affected on suppression of plant pathogens, the isolates could be differ from each other in modes of action. Further studies on mechanisms and practical applications are being progressed.

• The Korean Journal of Pharmacology
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• v.9 no.2
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• pp.1-6
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• 1973

Although numerous drugs are available for the treatment of superficial fungi infections of skin, the clinical effects of the majority of such drugs are not satisfactory. In the hope of searching the effective drugs for superficial fungi infections, authors studied whether Veratrum rhizoma extracts had any effect on fungi, with water extract (VRWE), ethanol extract (VREE) and methanol extract (VRME) from Veratrum album L. var. grandiflorum Max. In in vitro studies, the spores of fungi were inoculated on Sabouraud's glucose agar media which contained three extracts of Veratrun rhizoma in each concentration of $500\;{\mu}g/ml$, $1,000\;{\mu}g/ml$ and $5,000\;{\mu}g/ml$ respectively, and the growth of the fungi were observed for 3 weeks. The species of the fungi used in these experiments were Epidermophyton floccosum, Microsporum canis, Microsporum nanum, Microsporum gypseum, Microsporum cookei, Trichophyton rubrum, Trichophyton mentagrophytes, Trichophyton tonsurans and Trichophyton verrucosum. The results of the studies were as follows: 1. The growth of M. canis, M. nanum, T mentagrophytes and T. tonsurans were slightly inhibited by VRWE $1,000\;{\mu}g/ml$, and with VRWE $5,000\;{\mu}g/ml$, the growth of E. floccosum, M. gypseum and T. rubrum were slightly inhibited, moderate inhibition on the growth of M. canis, M. nanum, M. cookei, T. mentagrophytes and T. tonsurans were showed by VRWE $5,000\;{\mu}g/ml$. 2. With $500\;{\mu}g/ml$ of VREE, the inhibition on growth of E. floccosum, M. nanum and M. gypseum were slight, however significant inhibition on the growth of M. canis, M. cookei, T. mentagrophytes, T. rubrum and T. tonsurans were observed. The growth of M. nanum and M. gypseum were moderately inhibited, and significant inhibition on the growth of E. floccosum, M. canis, M. cookei, T. mentagrophytes, T. rubrum and T. tonsurans were observed by VREE $1,000\;{\mu}g/ml$. By VREE $5,000\;{\mu}g/ml$, the growth of all tested fungi were significantly inhibited except T. verrucosuia being showed slight inhibition. 3. Significant inhibition on the growth of M. canis, T, mentagrophytes, T. rubrum and T. tonsurans were noted, and moderate inhibition of M. nanum, slight inhibition of E. floccosum and M. gypseum in growth were observed by VRME $500\;{\mu}g/ml$. The growth of E. floccosum, M. canis, M. nanum, M. cookei, T. mentsgrophytes, T. rubrum and T. tonsurans were significantly inhibited by VRME $1,000\;{\mu}g/ml$, and that of M. gypseum was moderate. With $5,000\;{\mu}g/ml$ of VRME, significant inhibition on the growth of E. floccosum, M. canis, M. nanum, M. gypseum, M. cookei, T mentagrophytes, T. rubrum and T. tonsurans were observed, and T. verrucosum was showed only slight inhibition. From the above results, it was found that the extracts of organic solvents from Veratrum rhizoma (VREE & VRME) exerted significant antifungal activity, and their effects were probably derived from the pharmacological action of steroidal alkaloids.

• Natural Product Sciences
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• v.23 no.2
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• pp.125-131
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• 2017

Clitoria ternatea or Commonly known blue pea, is a perennial climber crop native to Asian countries. The current study was aimed to evaluate the antimicrobial activity C. ternatea extract on food borne microorganisms and its antifungal effect on Penicillium expansum. The extract showed significant antimicrobial activity against 3 Gram positive bacteria, 2 Gram negative bacteria and 1 filamentous fungus on disc diffusion assay. The extract also showed good biocidal effect on all Gram positive bacteria tested and P. expansum. However, the kill curve analysis revealed that the fungicidal activity of the extract against P. expansum conidia was depend on the concentration of the extract and the time of exposure of the conidia to the extract. The scanning electron micrograph of the extract treated P. expansum culture showed alterations in the morphology of fungal hyphae. The germination of P. expansum conidia was completely inhibited and conidial development was totally suppressed by the extract, suggesting the possible mode of action of anthocyanin. Besides, the extract also exhibited 5.0-log suppression of microbial growth relative to control in the rice model. The results indicate the potential use of the C. ternatea anthocyanin as food biopreservative.