• The Plant Pathology Journal
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• 제15권1호
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• pp.14-20
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• 1999

Twenty isolates of Helminthosporium species were obtained from various grass plants and tested for controlling efficacy on the development of plant diseases. An isolate of Helminthosporium sp. TP-4 was chosen and six antibiotic substances were purified from cultures of the fungus by repeated silica gel column chromatography and preparative thin-layer chromatography. They were identified as ophiobolin a, 6-epiophiobolin A, 3-anhydroophiobolin A, 3-anhydro-6-epiophiobolin A, iphiobolin B, and iphiobolin I mainly by mass spectrometry and nuclear magnetic resonance spectrometry. Ophiobolins inhibited the growth of a grampositive bacterium Streptomyces griseus, but were not active against gram-negative bacteria. They also showed an antifungal activity. In in vivo tests, iphiobolin B exhibited potent controlling activities against rice blast, tomato late blight, and wheat leaf rust with control values more than 90% and 70% at concentration of $500\mu\textrm{m}$/ml and 100 ${\mu}{\textrm}{m}$/ml. Ophiobolin A and 6-epiophiobolin A controlled the development of wheat leaf rust more than 80% at concentrations of 100 /ml and $500\mu\textrm{m}$/ml respectively. 3-Anhydro-6-epiophiobolin A was not active against any plant disease. On the other hand, the A-series ophiobolins other than 3-anhydroophiobolin A showed stronger phytotoxic activity in a leaf-wounding assay using 8 plant species than those of 3-anhydroophiobolin A, ophiobolin B, and ophiobolin I. The results indicate that there is little correlation between antifungal activity and phytotoxicity of ophiobolins.

• Applied Biological Chemistry
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• 제37권5호
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• pp.402-408
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• 1994

생리활성물질 monocerin의 구조상관활성을 조사하기 위해서 (8S, 9S, 11R)-(-)-monocerin과 (9S, 11R)-(+)-Fusarentin 4, 5-dimethyl ether를 합성하였는데, 합성은 benzylic anion과 유기용매에서 빵효모를 이용한 생체촉매반응으로 얻어진 (R)-aldehyde와의 축합에 의해 완성되었다. 합성되어진 화합물들은 병와 양상치를 대상으로 생리활성을 조사하였다. 특히, 벼의 생리활성검사에서 monocerin은 제2전엽보다 뿌리의 신장을 더 저해하였는데, fusarentin 4, 5-dimethyl ether는 제2전엽의 신장을 더 저해하였다. 생리활성시험의 결과, monocerin의 C환은 생리활성에 영향을 미치지 않는다는 사실이 예견되었고, 천연물의 입체구조적 배치가 비천연물의 입체구조적 배치보다 더 높은 생물활성을 나타내고 있다는 사실을 알 수 있었다.

• The Korean Journal of Ecology
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• 제20권3호
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• pp.181-189
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• 1997

Phenolic compounds from 7 species of naturalized invader species and Korean wild plants were analyzed by high performance liquid chromatography. Eleven phenolic compounds including benzoic acid were identified. The extract of naturalized plants was significantly more inhibitory to seed germination and seedling growth of the both naturalized and Korean wild plants. The content of total phenolic compounds in each extract were 43.5 mg/l in Ailanthus altissima as the maximum amount and 25.5 mg/l in Phytolacca americana as the minimum. Phytotoxic substances of ethanol extracts was investigated for antifungal activity against 23 selected fungus species. The antifungal activity of Phytolacca americana showed the greatest clear zone of 23 mm in Aspergillus awamori and its activity had an effect against 6 fungus species. Ailanthus altissima formed the greatest clear zone of 26 mm in Erwinia carotovora sub. sp. carotovora and had an effect agsinst 2 fungus species.

• 한국자원식물학회지
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• 제19권3호
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• pp.405-410
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• 2006

A series of aqueous or methanol extracts from four different Korean salad plants were assayed to determine their allelopathy and antioxidant activity. The extracts applied on filter paper in a Petri-dish bioassay significantly inhibited root growth of against alfalfa (Medicago sativa) seedlings. Leaf extracts from 40 g dry tissue $L^{-1}$ of Aster yomena was most phytotoxic to alfalfa root growth, and followed by that of Cirsium japonicum, Taraxacum officinale, and Ixeris dentate. Methanol extracts of plants dose-dependently increased DPPH free radical scavenging activity in vitro. Antioxidant activity of methanol extracts from the same plant species was investigated, and the result showed high DPPH free radical scavenging activity in Cirsium japonicum, Aster yomena, and Ixeris dentate, however, in Taraxacum officinale was least activity. By means of HPLC analysis, chlorogenic acid, p-coumaric acid, and total phenolics with 7.68, 17.47 and 18.64 mg, $100g^{-1}$, respectively, showed the highest amounts in methanol extracts from Cirsium japonicum leaves. These results suggest that Compositae salad plants contain water-soluble substances with allelopathic potential as well as antioxidant activity.

• 아시안잔디학회지
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• 제12권3호
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• pp.183-194
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• 1998

21과 30종의 약용식물의 Rhizoctonia solani AG1-1(brown patch)와 R. solani AG2-2(large patch)에 대한 항균활성을 조사한 결과 계피, 목단피, 백선피가 강한 항균활성을 나타내었다. R. solani AG1-1에 있어 계피와 목단피는 100％ methanol로 추출한 것이 활성이 가장 높게 나왔으며 백선피는 80％ methanol로 추출한 것이 높게 나왔다. 반면에 R. solani AG2-2에 있어서는 모두 100％ methanol에서 활성이 가장 높게 나왔다. 농도별 활성은 이들 조추출물의 500배 희석액에서 60%이상 공시균주의 균사생장이 억제되었다. 항균specturum은 목단피가 가장 넓었다. 계피조추출물은 250배이상 희석액에서 목단피의 조추출물은 100배이상 희석액에서 약해를 나타내지 않았으며 백선피의 조추출물은 전혀 약해를 나타내지 않았다. 처리 30일후 방제가는 목단피 처리구 75.0％, 백선피 처리구 79.1%로였다.

• The Plant Pathology Journal
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• 제20권1호
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• pp.52-57
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• 2004

Sclerotinia sp. (isolate BWC98-105) causes stem blight and root rot in Leghum sp., and is presently being evaluated as a potential mycoherbicide for the control of Trifoliorium repens. Bioassays have shown that Sclerotinia sp. produces phytotoxic substance which is biologically active against T. repens. Two biologically active compounds, designated as compoundsI and II, were produced in vitro from the culture filtrate of BWC98-105 isolate Sclerotium sp. Compounds I and II were purified by means of liquid-liquid extraction and $C_{18}$ open column chromatography (300 ${\times}$ 30 mm, i.d). To determine the purity, the purified compounds were analyzed by RP-HPLC. The analytical RP-HPLC column was a TOSOH ODS-120T (150 ${\times}$ 4.6 mm i.d, Japan), of which the flow rate was set at 0.7 mL/min using the linear gradient solvent system initiated with 15 % methanol to 85 % methanol for 50 min with monitoring at 254 nm. Under these RP-HPLC conditions, compounds I and II eluted at 3.49 and 4.13 min, respectively. Compound II was found to be most potent and host specific. However, compound I had a unique antibiotic activity against phytopathogenic bacteria like bacterial leaf blight (Xanthomonas oryzae) on rice, where it played a less important role in producing toxicity on T. repens. No toxin activity was detected in the water fraction after partitioning with several organic solvents. However, toxin activity was detected in the ethyl acetate and butanol fractions. In the leaf bioassay using compound II, the disease first appeared within 4-5 h as water soaked rot, which subsequently developed into well-defined blight affecting the whole plant.

• The Korean Journal of Ecology
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• 제14권2호
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• pp.149-157
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• 1991

To find out allelopathic potential of naturally occurring substances emitted form pinus korairnsis, water extracts and volatile sudstances of the tree materials werw provided and used for tests such as seed germination and seedling growth test. In general, the more was the concentration of the extracts and essential oils, the worse was growth effects of the selected species. The germination an the growth were inversely proportional to the concentration of the extracts and the essential oils of p. koraiensis. in other words, the chemical substances had the biological toxic activity. gc and gc/ms methods were employed for analysis and identification of phytotoxic substances from the tree leaves. Sixteen chemical compounds were identified from water extracts and nineteen from essential oils of p. koraiensis leaves. Through the experiment on germination and seedling growth test, the chemical substances naturally occurring from p. koraiensis seemed to be responsible for the allelopathic potential in this study.

• Plant Resources
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• 제7권1호
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• pp.69-76
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• 2004

Lettuce (Lactuca sativa L.) is known to contain water-soluble substances that are biologically active. Aqueous or methanol extracts and residues from leaves of lettuce plants were assayed to determine their allelopathic effects, and the causative allelochemicals from fractions were quantified by means of HPLC analysis and bioassayed. Extracts from oven-dried leaf samples were more phytotoxic than those from freeze-dried samples. Leaf extracts of 40 g L$^{-1}$ were completely inhibitory on root growth of alfalfa (Medicago sativa L.), while root growths of barley (Hordeum vulgare L.) and soybean (Glycine max L.) were less sensitive. Early seedling growth of both alfalfa and barnyard grass (Echinochloa crus-galli) was significantly reduced by methanol leaf extracts. The major allelopathic substances analyzed by HPLC were coumarin, trans-cinnamic acid, o-coumaric acid, p-coumaric acid and chlorogenic acid. Of them p-coumaric acid was found as the greatest amount (8.9 mg 100 g$^{-1}$ ) in the EtOAc fraction; only coumarin was found in all the fractions. Hexane and EtOAc fractions of L. sativa reduced alfalfa root growth more than did BuOH and water fractions. These results suggest that lettuce had potent herbicidal activity, and that its activity differed depending on type and amount of causative compounds by fraction.

• The Plant Pathology Journal
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• 제24권4호
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• pp.461-468
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• 2008

An endophytic bacterial strain YC5480 producing antifungal and phytotoxic compounds simultaneously was isolated from the surface sterilized root of Artemisia sp. collected at Jinju area, Korea. The bacterial strain was identified as a species of Pseudomonas brassicacearum based on its 16S rRNA gene sequence analysis and physiological and biochemical characteristics. The seed germination and growth of monocot and dicot plants were inhibited by culture filtrate (1/10-strength Tryptic Soy Broth) of the strain. The germination rate of radish seeds in the culture filtrate differed in various culture media. Only 20% of radish seeds germinated in the culture media of 1/2 TSB for 5 days incubation. Mycelial growth of fungal pathogens, Colletotrichum gloeosporioides, Fusarium oxysporum and Phytophthora capsici was also inhibited by the culture filtrate of the strain YC5480. An antifungal compound, KS-1 with slight inhibitory activity of radish seed germination at 1,000 ppm and a seed germination inhibitory compound, KS-2 without suppression of fungal growth were produced simultaneously in TSB. The compounds KS-1 and KS-2 were identified to be 2,4-diacetylphloroglucinol (DAPG) and 2,4,6-trihydroxyacetophenone (THA), respectively.

• 한국자원식물학회지
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• 제10권4호
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• pp.351-359
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• 1997

3가지의 식물체 추출액을 공시하여 P. capsici에 대한 항균 활성 검정, 고추 역병에 대한 방제효과 및 고추에 미치는 약해를 조사한 결과는 다음과 같다. 1. 3가지 식물체 물 추출액 중에서 일황련 추출애기 균새장 억제효과가 가장 뛰어났으며, 2배의 희석농도에서 70% 이상의 억제 효과가 있었고, methanol 추출액의 경우 1,000배 이상의 희석농도에서도 74.4%의 억제 효과가 있었다. 지모 및 일황련 추출액의 2개 희석농도와 황백나무의 추출원액 처리에 의해 P.capsici의 유주자낭의 발아는 완전히 억제되었다. 2. Methanol에 의한 추출액이 상온에서 물에 의해 추출하거나, 끓여서 추출한 액보다 항균력이 우수하였다. 3. 세 가지 식물체 추출액 모두 저장기간이 길어짐에 따라 고추 역병균에 대한 항균력은 감소하는 경향을 보였다. 4. 세 가지 추출액 모두 고추 역병에 대해서 방제효과가 있었고, 그 중 일황련 추출액이 가자 효과적이며 황백나무 및 지모의 순이었다. 5. 수경 재배형식의 유모검정에서는 고추묘에 약해가 있었으나, pot시험에서는 약해가 없었다. 또한 고추 종자에 추출액을 처리했을 때 발아가 저해되거나 유근의 신장이 억제되는 등 약해가 유발되어쓰나, 고추 잎과 고추 과실에 추출애글 엽면살포 하였을 때에는 아무런 해가 나타나지 않았다.