• Korean Journal of Agricultural Science
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• v.48 no.2
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• pp.343-351
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• 2021

Screening was conducted using 200 kinds of plant extracts to explore herbicide-activated components of plant origin. We separated and purified active substances and elucidated chemical structures using Ligularia stenocephala M., which has strong activity and has not yet been studied. When the solvent fractions of the leaves of Ligularia stenocephala M. were tested for their herbicidal activity, ethyl acetate and chloroform layer showed an inhibition rate of 95.2% and 94.1%, respectively. In particular, the chloroform layer exerted more than 50% herbicidal activity at 10 ppm. From the chloroform layer with the highest herbicidal activity, we isolated three herbicidal active compounds using stepwise chromatography, specifically silica gel or octadecyl silica (ODS) column chromatography, Sep-pak cartridges, and high performance liquid chromatography (HPLC). Based on the analysis of the active compounds using electron ionization mass spectroscopy (EI-MS), ¹H-NMR, and ¹³C-NMR, we identified the active compounds as euparin, 5,6-dimethoxy-2-isopropenylbenzofuran, and liguhodgsonal. When the herbicidal activity of the identified compounds was tested, euparin showed selective herbicidal activity for lettuce at 10^-3 M, and both liguhogsonal and 5,6-dimethoxy-2-isoprophenylbenzofuran exerted selective activity for rice and Echinochloa crus-galli.

• Korean Journal of Plant Resources
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• v.9 no.1
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• pp.47-54
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• 1996

To search herbicidal compounds in Pulsatilla koreana Nakai, methanol extract of P. koreana roots was purified by sequences of XAD-7 column chromatography, silica gel adsorption column chromatography, silica gel flash column chromatography, preparative layer chromatography and preparative high performance liquid chromatography(Prep, HPLC).The final Prep. HPLC gave two herbicidally-active fractions. These fractions treatment at 100ppm inhibited the root length of Echinochloa crus-galli seedlings by 48% and 60% as compared with the control, respectively. Components in the two active fractions were analyzed by GC-MS Spectrometry. These compounds, which were isolated from P. koreana roots, were identified as several fatty esters, hydrocarbons, squalene, evidonol, and a diazepin analogue.

• The Korean Journal of Pesticide Science
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• v.5 no.4
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• pp.68-71
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• 2001

Of the cyclic imide type compounds, S-275 was known to exhibit a potent herbicidal effects. We have designed and synthesized the compounds having diverse subsutuents in place of the chlorine group of bicyclic 4,5,6,7-tetrahydroindazole part of S-275. Their herbicidal activities were studied under flooded paddy conditions. The results showed that the most compounds gave relatively weak herbicidal activities, whereas tile compound substituted with methylthio group showed potent herbicidal effects against paddy weeds at a rate of 0.015 kg/ha and improved tolerance on rice compared to S-275.

• The Korean Journal of Pesticide Science
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• v.4 no.3
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• pp.15-18
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• 2000

A series of N-{2,4-dichloro-5-(3-pyrazolyl)Phenyl}imides 7 and 8 was prepared and evaluated their herbicidal activities. Those compounds in which either carboxylate or carboxamide moiety is on pyrazole moiety 7c-71 showed no herbicidal activity whereas, the compounds in which trifluoromethyl group is substituted in pyrazolyl moiety showed moderate herbicidal activities against barnyardgrass, monochria and flat-sedge under paddy conditions with good rice tolerance at rate 63-250 g/ha.

• The Korean Journal of Pesticide Science
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• v.11 no.2
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• pp.67-71
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• 2007

Nobel series of 5-benzyloxymethyl-3-(thiophen-5-yl)-1,2-isoxazoline derivatives were designed and synthesized. The herbicidal activities of these compounds to main dominant weeds to these compounds were evaluated in pot tests that simulated rice paddy conditions. Most of the compounds showed high herbicidal activity to main dominant weeds occurring in rice field without the serious rice injury.

• The Korean Journal of Pesticide Science
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• v.7 no.4
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• pp.248-257
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• 2003

The objective of this experiment was to search plant species with herbicidal activity in Korea. Two hundred native plants were collected and their methanol extracts were obtained. Herbicidal activity of methanol extracts were determined by seed bioassay using canola (Brassica napus L.) seedlings. Six plants such as Staphylea bumalda, Wistaria floribunda, Allium victorialis, Rumex crispus, Chionanthus retusa, and Ulmus parvifolia were highly herbicidal: their $GR_{50}$ values were < $1,000{\mu}g\;g^{-1}$. In addition, seventeen plants such as Galium spurium, Zelkova serrata, Campsis grandiflora, Eucommia ulmoides, Sorbus commixta, Deutzia glabrata, Cercis chinensis, Alnus hirsuta, Zanthoxylum schinifolium, Quercus acutissima, Robinia pseudoacacia, Gleditsia japonica, Kerria japonica, Ligustrum obtusifolium, Thuja orientalis, Chamaecyparis obtusa, and Pulsatilla koreana showed herbicidal activity: their $GR_{50}$ values were between 1,000 and $2,000{\mu}g\;g^{-1}$. However, 177 plants showed no herbicidal activity. Plants with herbicidal activity found in this study could be used for weed management and herbicidal compounds in such herbicidal plants could be used as lead compounds in the development of new herbicides.

• The Korean Journal of Pesticide Science
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• v.3 no.3
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• pp.1-5
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• 1999

Novel O-quinolinylamidoxime derivatives were prepared by replacement of the carboxylic group at the 8 position of quinclorac with various amidoximes. In the flooded paddy conditions, most of the compounds show good herbicidal activity at a rate of 1 kg/ha. Some of them showed excellent herbicidal activity at a rate of 60 g/ha against barnyardgrass (Echinochloa aryicola) with good selectivity on rice. Under the two-leaf stage of barnyardgrass, most of O-quinolinylamidoximes showed good herbicidal activity, expecially compound 3c which showed excellent herbicidal activity barnyardgrass at a rate of 125 g/ha with good rice seletivity.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.437-444
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• 2010

This study was conducted to determine the herbicidal activity of allelochemicals and identify herbicidal compounds in bulbs of Lycoris chinensis var. sinuolata. Methanol extract was purified by a series of silica gel flash column chromatography and HPLC. The final HPLC gave two active fractions and an herbicidal compound was obtained. By GC/MS analysis, the herbicidal compound was identified as montanine ($O^2$-methyl pancracine), an isoquinoline alkaloid. Montanine showed 100% of growth inhibition on the shoot and root of barnyardgrass (Echinochloa crus-galli) seedlings at $50\;{\mu}g\;mL^{-1}$ as compared with the control.

• The Korean Journal of Pesticide Science
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• v.9 no.2
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• pp.181-184
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• 2005

The heterocyclic PPO inhibitor compounds have been studied due to their potent herbicidal effects without toxic to human and animals. We have designed and synthesized 4,5,6,7-tetrahydroindazole, maleimide, and tetrahydrophthalimide compounds carrying diverse epoxide substituents at 5- position of the phenyl group. Their herbicidal activities were evaluated under submerged paddy conditions. These results showed that 4,5,6,7-tetrahydroindazole compounds gave potent herbicidal activities especially to ECHOR, MOOVA, and CYPSE at a relatively low rate of 16 g/ha and improved tolerance on rice compared to S-275 as a standard herbicide in this experiment.

• Applied Biological Chemistry
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• v.39 no.2
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• pp.153-158
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• 1996

During the screening of herbicidal substances from microbial secondary metabolites using photoautotrophic cells, a strain of ME-13 with strong herbicidal activity was isolated from soil. Based on the taxonomic studies, the strain was identified as Streptomyces. Two active compounds were purified from the culture broth through the column chromatographies using active charcoal, silica gel, MCI gel, and ODS HPLC. The compounds were identified as AB3217-A and B, respectively, related to anisomycin by spectroscopic methods. AB3217-A and B completely suppressed the germination of radish and barnyard grass at 25 ppm. In comparison to anisomycin, they showed the 6 times higher inhibitory activities against the growth of shoot and root of radish and barnyard grass with EC5O of around 6 ppm.