• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1013-1014
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• 1995

• Applied Biological Chemistry
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• v.31 no.1
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• pp.79-85
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• 1988

The effects of herbicides on biochemical processes in soil environment were studied by examining the effects of the chemical structure of each herbicides on soil enzyme activities and pesticides residue revealed when soil treated with urea was incubated at $28{\pm}1^{\circ}C$ for 56 days. The inhibition effects of herbicides on soil enzyme activites in soil decreased in the order of urea group>dinoseb>propanil>diphenyl eter group>acid amide group for urease, and dinoseb>urea group>diphenyl ether group>acid amide group for L-glutaminase and protease, dinoseb>diphenyl ether group>urea group>acid amide group for phosphatase. Herbicides inhibited the activities of soil enzyme in the early stage of treatment but increased the activities of urease, L-glutaminase and protease in the late stage. When herbicides were treated in soil together with urea the degradation of insecticides was accelerated.

• Korean Journal of Weed Science
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• v.10 no.4
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• pp.255-260
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• 1990

Seventeen different herbicides were screened to select promising ones for the control of weeds, which may be used in paddy fields transplanted with 8 days old young rice seedlings. Four classes of herbicides were chosen and tested with seedlings grown under different cultivating conditions. Contact herbicides such as diphenyl-ether and oxadiazol showed severe growth retardation of rice seedlings. Carbamate class(dimepiperate), quinoline class (quinclorac), pyrazol class(pyrazolate), acid amide class(mefenacet and pretilachlor), addition of safener (pretilachlor+fenclorim and mefenacet+bensulfuron+dymuron) and unknown class (KC-7079) exhibited normal growth of seedlings. Sulfonyl urea herbicide class(cimosulfuron, bensulfuron, pyrazosulfuron), and oxarane class(tridiphane) showed the slight growth inhibition but recovered shortly.

• Applied Biological Chemistry
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• v.17 no.3
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• pp.149-176
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• 1974

Eight substituted diphenyl ether herbicides and some of their photoproducts were studied in terms of solution phase photolysis under simulated environmental conditions by using a Rayonet photochemical reactor. The test compounds absorbed sufficient light energy at the wavelength of 300 nm to undergo various photoreactions. All the photoproducts were confirmed by means of tlc, glc, ir, ms, and/or nmr spectrometry. The results obtained are summarized as follows: Solution phase photolysis of C-6989: An exceedingly large amount of p-nitrophenol formed strongly indicates the readiness of the ether linkage cleavage of this compound as the main reaction in all solvents used. Photoreduction of nitro to amino group(s) and photooxidation of trifluoromethyl to carboxyl group were recognized as minor reactions. Aqueous photolysis of p-nitrophenol: Quinone(0.28%), hydroquinone (0.66%), and p-aminophenol (0.42%) were confirmed as photoproducts, in addition to a relatively small amount of an unknown compound. The mechanisms of formation of these products were proposed to be the nitro-nitrite rearrangement via $n{\rightarrow}{\pi}^*$ excitation and the photoreduction through hydrogen abstractions by radicals, respectively. Solution phase photolysis of Nitrofen: Photochemical reduction leading to the p-amino derivative was the main reaction in n-hexane. In aqueous solution, the photoreduction of nitro to amino group and hydroxylation predominated over the ether linkage cleavage. Nucleophilic displacement of the nitro group by hydroxide ion and replacement of chlorine substituents by hydroxyl group or, to a lesser extent, hydrogen were also observed as minor reactoins. Solution phase photolysis of MO-338: Photoreduction of the nitro to amino group was marked in the n-hexane solution photolysis. In the aqueous solution, photoreduction of the nitro substituent and hydroxylation were the main reactions with replacement of chlorine substituents by the hydroxyl group and hydrogen, and cleavage of the ether linkage as minor reactions. Photolyses of MC-4379, MC-3761, MC-5127, MC-6063, and MC-7181 in n-hexane and cyclohexane: Photoreduction of the nitro group leading to the corresponding amino derivative and replacement of one of the halogen substituents by hydrogen from the solvent used were the key reactions in each compound. Aqueous photolysis of MC-4379: Cleavage of the ether linkage, replacement of the carboxymethyl by hydroxyl group, hydroxylation, and replacement of the nitro by hydroxy group were prominent with photoreduction and dechlorination as minor reactions. Aqueous photolysis of MC-3761: Cleavage of the ether linkage, replacement of the carboxymethyl by hydroxyl group, and photoreduction followed by hydroxylation were the main reactions. Aqueous photolysis of MC-5127: Replacement of carboxyethyl by hydrogen was predominant with ether linkage cleavage, photoreduction, and dechlorination as minor reactions. It was obvious that the decarboxyethylation proceeded more readily than decarboxymethylation occurring in the other compounds. Aqueous photolysis of MC-6063: Cleavage of the ether linkage and photodechlorination were the main reactions. Aqueous photolysis of MC-7181: Replacement of the carboxymethyl group by hydrogen and monodechlorination were the remarkable reactions. Cleavage of the ether linkage and hydroxylation were thought to be the minor reactions. Aqueous photolysis of 3-carboxymethyl-4-nitrophenol: The photo-induced Fries rearrangement common to aromatic esters did not appear to occur in the carboxymethyl group of this type of compound. Conversion of nitro to nitroso group was the main reaction.

• BMB Reports
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• v.34 no.1
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• pp.39-42
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• 2001

Previous studies indicate that B. subtilis protoporphyrinogen oxidase is poorly inhibited by diphenyl ether herbicides. To better understand the basis of this insensitivity, the enzyme was overexpressed as a soluble protein in E. coli, purified and characterized. The mechanism of oxidation of B. subtilis protoporphyrinogen IX was studied and the enzyme kinetic parameters were determined for protoporpyrinogen IX; $K_m$, and $k_{cat}$ were $6.3\;{\mu}M$ and $0.028\;h-^1$, respectively. The enzyme required flavin adenine dinucleotide as a cofactor and its activity was enhanced by 1 mM n-octylglucopyranoside. The nonenzymatic oxidation rate was dependent on the concentration of protoporphyrinogen IX, suggesting that the reaction involves a pre-equilibrium step followed by a rate-limiting step.

• Korean Journal of Weed Science
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• v.18 no.1
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• pp.69-75
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• 1998

Responses of tobacco(Nicotiana tabacum cv. Xanthi) leaves of different age to diphenyl ether herbicide oxyfluorfen were evaluated with respect to cellular leakage, chlorophyll loss, and membrane lipid peroxidation. When tobacco leaves of different age were incubated under light condition at $25^{\circ}C$ following 12hr dark incubation. Significant electrolyte leakage from the treated tissues into the bathing medium occurred. The change of electrolyte leakage was proportional to the oxytluorfen concentration and the duration of light exposure to the tissues. Electrolyte leakage from the tissues treated with oxyfluorfen was highly dependent on the leaf age. From the tissues of younger age, more electrolyte leakage occurred and lag period was greatly reduced. Chlorophyll loss and membrane lipid peroxidation, as measured by malondialdehyde production, caused by oxyfluorfen treatment were also dependent an the age of treated leaf tissues. In conclusion, physiological responses of tobacco leaves to oxyfluorfen greatly varied with the age of treated tissues, and thus tobacco plants could be used as appropriate materials for studying the mechanisms of tolerance to diphenyl ether herbicides.

• Korean Journal of Weed Science
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• v.18 no.3
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• pp.237-245
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• 1998

The transgenic tobacco (Nicotiana tabacum cv. Xanthi) plants containing Bacillus subtilis protoporphyrinogen oxidase gene with cauliflower mosaic virus 35S promoter have recently been generated by using Agrobacterium-mediated gene transformation. The nontransgenic and the transgenic tobacco plants were compared with respect to responses to diphenyl ether herbicide oxyfluorfen and under various environmental conditions. Both cellular leakage and lipid peroxidation caused by oxyfluorfen were found to be less in the transgenic than in the nontransgenic plants. Growth responses of the transgenic plants under various temperature, light, and water conditions were almost the same as those of the nontransgenic plants, although the transgenic plants exhibited slightly more retarded growth under low light or saturated water condition. These results revealed that the transgenic tobacco plants containing B. subtilis protoporphyrinogen oxidase gene under cauliflower mosaic virus 35S promoter were relatively resistant to oxyfluorfen and exhibited normal growth pattern. Possible mechanism of resistance to oxyfluorfen in the transgenic plants is also discussed.

• Korean Journal of Weed Science
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• v.16 no.4
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• pp.337-345
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• 1996

This study was conducted to investigate the protox activity, the PPIX accumulation and the activity of antioxidative enzymes of the oxyfluorfen-tolerant and -susceptible rice cultivars by oxyfluorfen and oxytluorfen-similar herbicides treatment. When treated with acifluorfen, bifenox or oxadiazon, the oxyfluorfen-tolerant rice cultivars showed less decreased in fresh weight than the susceptible rice cultivars. The inhibition of protox activity was in the order of acifluorfen > oxyfluorfen > bifenox > oxadiazon, and the PPIX accumulation was in the sequence of oxadiazon > acifluorfen > oxyfluorfen > bifenox. The inhibition of protox activity and the PPIX accumulation by the herbicide was greater in the susceptible rice cultivars than in the tolerant rice cultivars. The effect inhibiting the decrease of chlorophyll content resulting from the treatment of GC, tetrapyrrole biosynthesis inhibitor, was in the order of oxyfluorfen > acifluorfen > bifenox > oxadiazon, and the tolerant rice cultivar had more than the susceptible rice cultivar. In the treatment of DPE and oxadiazon, the activities of MDAR, POX and GR was higher in the tolerant rice cultivar than in the susceptible rice cultivar, and in the case of POX isozyme the activities of main D and E bands increased in the tolerant rice cultivars at tested herbicides but they didn't in the susceptible rice cultivar.

• Korean Journal of Weed Science
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• v.16 no.1
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• pp.54-63
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• 1996

This study was conducted to investigate the anatomical and ultrastructural responses of the oxyfluorfen-tolerant and -susceptible rice cultivars with barnyardgrass, a typical susceptible weed by oxyfluorfen and the herbicides having similar mode of action treatment. After the treatment of $10^{-5}M$ oxyfluorfen, the tolerant rice cultivars no showed the structural damage of leaf surface, but the susceptible rice cultivate was damaged in the wax and the susceptible barnyardgrass was even destroyed in the tissue irregularly. Also in the susceptible rice cultivars and barnyardgrass the thickness of leaf blade was greatly decreased. The anatomical change was not observed in the tolerant rice cultivars but epidermal cells, mesophyll cells and bundle sheath cells were badly broken in the susceptible rice cultivars and barnyardgrass and especially after 24 hours of the treatment the structure of susceptible rice cultivars was completely disintegrated. The irregularity of chloroplast shape and the distortion of chloroplast envelope were generally observed and the starch tended to decrease by oxyfluorfen treatment regardless of rice cultivars. Such a structural damage were appeared more badly in the susceptible rice cultivars and bamyardgrass than in the tolerant rice cultivars. By the treatment of diphenyl ether herbicides, the thickness of leaf blade greatly reduced in the order of oxyfluorfen > acifluorfen > bifenox > oxadiazon, and the susceptible rice cultivars showed more reduction than the tolerant rice cultivars. Especially, the susceptible rice cultivars showed that the leaf structure was badly broken down with damage epidermal cells and bundle sheath cells.

• Korean Journal of Weed Science
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• v.14 no.2
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• pp.107-111
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• 1994

Selective action of root-treated oxyfluorfen [(2-chloro-4-thrifluoromethylphenyl)-3'-ethoxy-4'-nitrophenyl ether] and chlomethoxynil [2, 4-dichlorophenyl-3'-methoxy-4'-nitrophenyl ether] were investigated. Oxyfluorfen showed greater activity to all plant species than chlomethoxynil. $^{14}C$-oxyfluorfen was little metabolized in roots of the plant species and more slowly absorbed than $^{14}C$-chlomethoxynil. These results suggest that herbicidal activity of oxyfluorfen at the site of action is higher than chlomethoxynil. In the tested plants, rice, barnyardgrass, sorghum, and corn were absorbed less of the oxyfluorfen and chlomethoxynil than the broad leaf plant species. However, no clear relationship was observed between a degree of tolerance and absorption and metabolism of both herbicides by the plant species.