• 한국유기농업학회지
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• 제28권1호
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• pp.95-108
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• 2020

To develop an environment-friendly fungicide for controlling tomato wilt diseases, antifungal active substance was isolated Rheum australe D. Don roots against Fusarium oxysporum f. sp. lycopersici, a pathogen of tomato wilt, in this study. Methanol extract obtained from Rheum australe roots was successively fractionated with hexane, chloroform, ethyl acetate, butanol and water. The ethyl acetate fraction, which showed the highest antifungal activity, was separated by column chromatography, and 60 subfractions were obtained. The 60 subfractions were anlayzed for antifungal activities by bioassay. The active compound was identified as 5-[(E)-2- (3-hydroxy-4-methoxyphenyl)ethenyl]benzene-1,3-diol (rhapontigenin) by NMR and GC-MS analysis. As a result of testing antifungal activity of rhapontigenin against Fusarium oxysporum, EC₅₀ of rhapontigenin was showed strong antifungal activity at 7.48 mg/L. Therefore, this study showed that the Rheum australe roots extract can be a potential candidate which is a environment-friendly fungicide against Fusarium oxysporum.

• The Plant Pathology Journal
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• 제16권4호
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• pp.189-199
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• 2000

To search for the antifungal substances, various actino-mycete isolates were obtained from various soils of Korea using plate dilution method on the humic acid vitamin agar plates. In the screening procedures using a dual culture method, 32 actionomycete isolates were selected, which showed the inhibitory activity against mycelial growth of plant pathogenic fungi Altirnaria mali, Colletotrichum gloeosporides, Fusarium oxysporum f.sp. cucumerinum, Magnaporthe grisea, Phytophthora capsici, and Rhizoctonia solani. Bioassay of the crude extracts from culture filtrates and mycelial mets revealed that 12 antagonistic actionomycetes produced highly active antifungal substances. Actinomycete strain S5-55 which showed the substantial antifungal activity against the tested fungi was selected for production of the antifungal substances. Based on the cytochemical and morphological characteristics, strain S5-55 was identified as a Streptomyces species. The results of the numerical identification using the TAXON program confirmed that Streptomyces strain S5-55 was identical with Streptomyces humidus including in TAXON major cluster 19. The production of antifungal substance was most favorable when S. humidus strain S5-55 was cultivated for 10 dats on soluble starch broth supplemented with $K_2$HPO$_4$. The antifungal substances active against the plant pathogenic fungi P. capsici and M. grisea were partially purified using $\textrm{C}_{18}$ reversed-phase column chromatography.

• The Plant Pathology Journal
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• 제18권2호
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• pp.102-105
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• 2002

A strain of Acremonium strictum, the mycoparasite of Botrytis cinerea, showed strong antifungal activities both in vitro and in vivo against several phytopathogenic fungi. An antifungal substance was purified from the liquid cultures of A. strictum and identified as verlamelin by instrumental analyses. Verlamelin exhibited in vitro antifungal activity against some phytopathogenic fungi such as Magnaporthe grisea, Bipolaris maydis, and Botrytis cinerea, while it was net active against all the bacteria tested. In viva, verlamelin exhibited strong protective and curative activities, particularly against barley powdery mildew. At 100 μg/ml, it inhibited the development of barley powdery mildew with control values of more than 90% in 7-day protective and 2-day curative applications. This is the first report on the production of verlamelin by Acremonium species.

• Journal of Microbiology and Biotechnology
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• 제28권2호
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• pp.262-266
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• 2018

Phytochemicals have been considered as alternatives for synthetic fungicides because of their biodegradability and low toxicity. In this study, we found that the methanolic extract of Corydalis ternata suppressed the development of plant diseases caused by Puccinia triticina and Colletotrichum coccodes. As the antifungal substance, three isoquinoline alkaloids (dehydrocorydaline, stylopine, and corydaline) were isolated from C. ternata. These active compounds also exhibited in vivo antifungal activity against P. triticina and C. coccodes. Taken together, our results suggest that C. ternata and its active compounds can be used to control plant diseases.

• The Plant Pathology Journal
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• 제23권3호
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• pp.180-186
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• 2007

The biocontrol agent, Serratia plymuthica A21-4, has been developed for controlling pepper Phytophthora blight. Serratia plymuthica A21-4 strongly inhibits the mycelial growth, zoospore formation, and cyst germination of Phytophthora capsici in vitro. The application of a cell suspension of strain A21-4 to pepper plants in pot experiments and in greenhouse successfully controlled the disease. The bacteria produced a potent antifungal substance which was a key factor in the suppression of Phytophthora capsici. The most active chemical com-pound was isolated and purified by antifungal activity-guided fractionation. The chemical structure was identified as a chlorinated macrolide $(C_{23}H_{31}O_8Cl)$ by spectroscopic (UV, IR, MS, and NMR) data, and was named macrocyclic lactone A21-4. The active compound significantly inhibited the formation of zoosporangia and zoospore and germination of cyst of P. capsici at concentrations lower than $0.0625{\mu}g/ml$. The effective concentrations of the macrocyclic lactone A21-4 for $ED_{50}$ of mycelial growth inhibition were $0.25{\mu}g/ml,\;0.25{\mu}g/ml,\;0.30{\mu}g/ml \;and\;0.75{\mu}g/ml$ against P. capsici, Pythium ultimum, Sclerotinia sclerotiorum and Botrytis cinerea, respectively.

• 한국미생물·생명공학회지
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• 제21권4호
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• pp.322-328
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• 1993

During the screening of antifungal compounds from microbial secondary metabolites to control phytophthora blight of red pepper caused by Phytophthora capsici, a soil isolate, strain 38D10 was selected. Based on taxonomic studies, this strain was identified as Streptomyces neyagawaensis. The antifungal compound was purified from culture broth by HP-20 column chromatography, ethyl acetate extraction, silica gel column chromatography, HPLC and identified as concanamycin B by UV. $^1H$-NMR, $^{13}C$-NMR, SIMS analysis. Concanamycin B has strong antifungal activity against some phytopathogenic fungi but not antivacterial activity and preventive value were 50% and 100% at 125ppm and 250ppm in pot assay.

• 한국유기농업학회지
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• 제23권4호
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• pp.887-896
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• 2015

본 연구는 균핵병의 원인균인 Sclerotinia sclerotiorum에 대해 항균활성을 갖는 친환경 유기농자재를 개발할 목적으로 송라(Usnea longissima)로부터 활성물질을 분리하였다. 송라를 MeOH로 추출하여 용매분획을 하였고, 용매분획 중에서 강한 활성을 나타낸 $CHCl_3$ fraction을 column chromatography로 분리하여 40개의 subfractions을 얻었고 9개의 그룹으로 나누었다. 9개의 subfractions을 bioassay한 결과 G3 subfraction에서 강한 활성을 나타내었다. G3 subfraction을 GC-MS로 분석하여 chromatogram 상의 활성물질로 추정되는 peak의 mass spectrum과 Wiley library를 비교하여 profiling한 결과, Usnic acid가 주요 물질로 검출되었다. 항균활성물질로 추정되는 Usnic acid 화합물의 항균활성을 검정하기 위하여 표준품을 사용하여 생물검정한 결과 이 화합물이 강한 활성을 나타내었다. 따라서 송라로부터 분리한 Usnic acid가 균핵병의 원인균인 Sclerotinia sclerotiorum에 대한 항균 활성물질인 것으로 추정하였다.

• 한국자원식물학회지
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• 제12권4호
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• pp.260-268
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• 1999

황련(Coptis japonica)의 추출액을 공시하여 Phytophthora capsici, Fusarium oxysporum, Colletotrichum dematium, C. truncatum, Botrytis cinerea, Botryosphaeria dothidea과 Alternaria porri에 대해 항균 활성 검정, 몇가지 작물에 대한 병해 방제 효과를 조사하고 항균 활성 물질을 동정하였다. 황련 추출액은 P. capsici, F. oxysporum, C. dematium, B. cinerea, B. dothidea 및 A. porri에 대해서 항균력이 우수하였다. Methanol을 용매로 추출하여 분리된 물질과 berberine-Cl 표준품의 항균활성을 비교할 때, 황련추출액으로부터 분리된 물질은 표준품 berberine-Cl과 비슷하게 항균력을 나타내었다. 황련 추출액은 고추 역병(83.3%), 참깨 모잘록병 (92.0%) 및 파 검은무늬병(87.5%)에 대해서 방제효과가 인정되었다. 고추 잎과 과실, 파 잎 및 딸기 과실에는 약해가 나타나지 않았으나 고농도에서는 고추 및 참깨의 발아를 억제하거나 유근의 신장을 억제하는 것으로 나타났다. Methanol로 추출한 황련 추출액으로부터 황색 분말 4.24g/100g을 얻을 수 있었다. 이들 물질을 HPLC로 분석한 결과 항균성을 나타내는 물질은 berberine-Cl로 동정되었다.

• Journal of Microbiology
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• 제34권3호
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• pp.284-288
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• 1996

Among the bacteria isolated from compost piles of cattle excretion in a pasture located at the suburbs of Chunchon city, Pseudomonas aeruginosa KMCS-1 was selected for the test of antifungal substances produced. Six fractions were separated by silica gel column chromatography, and then the antifungal activity of each fraction was assayed against Escherichia coli, Bacillus subtilis, Candida albicans, Rhizopus sp., Aspergillus nidulans, Coprinus cinereus, and Pyricularia oryzae by paper disc method. Two fractions showed significant suppressive activities against A. nidulans, C. cinereus, and P. oryzae however, their mycelial growth was not affected by neither of these fractions. Inhibitory activities of these fractions to sporulation was assayed at the concentration of 50. 25, 12. 5, and 6.25 $\mu$g/ml and the average inhibition rates against sporulation of A. nidulans, C. cinereus, and P. oryzae were 94.0, 98.3, and 77.9%, respectively. Further purification and analysis of active substances are now being conducted.

• Journal of Applied Biological Chemistry
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• 제60권3호
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• pp.265-269
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• 2017

Environment-friendly, commercially-available agricultural products were investigated for antimicrobial activity against Sclerotinia sclerotiorum, as a pathogen of sclerotium disease. Then ${\beta}$-thujaplicin from Chamaecyparis obtuse was investigated for antifungal activity against six kinds of pathogenic fungi. It showed a statistically significant (p <0.001) growth inhibition effect on Sclerotinia sclerotiorum as a pathogen of sclerotium disease, Rhizoctonia solani AG-4 as a pathogen of damping off, Phytophthora capsici as a pathogen of phytophthora blight, and Colletotrichum coccodes as a pathogen of anthracnose at a concentration of 50 ppm and on Stemphylium solani as a pathogen of spotting disease and Alternaria alternata as a pathogen of black mold at a concentration of 100 ppm. In conclusion, these results indicate that it may be possible to develop environment-friendly agricultural products using ${\beta}$-thujaplicin compounds.