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Jean-marc Bollag - One of the best experts on this subject based on the ideXlab platform.
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Effect of phenolic mediators and humic acid on Cyprodinil transformation in presence of birnessite
Water Research, 2004Co-Authors: Ki Hoon Kang, Heekyung Park, Jean-marc BollagAbstract:Abstract Naturally occurring phenols were evaluated as mediators for the transformation of the fungicide Cyprodinil by birnessite. With birnessite alone, Cyprodinil transformation was negligible (0.6%). In the presence of mediators, however, it increased considerably (1.5–60.9%). With some exceptions (2,6-dimethoxyphenol, syringic acid), methoxylated phenols showed a substantial capacity for enhancing the transformation. Mass spectrometry indicated that Cyprodinil cross-coupled with free radicals of phenols formed at birnessite surfaces. The extent of Cyprodinil transformation in the presence of syringaldehyde, m -methoxyphenol, or vanillin increased with the amount of birnessite. In reactions with o - and p -methoxyphenol and vanillic acid, Cyprodinil transformation was unaffected by the amount of birnessite, but it increased with increasing phenol concentration. The addition of various humic acids at low concentrations (5–10 mg/L) had little effect on Cyprodinil transformation in the presence of o -methoxyphenol or syringaldehyde. At higher concentrations, however, humic acids inhibited the transformation (by 5–20%) when o -methoxyphenol was a mediator, but showed no effect in the presence of syringaldehyde.
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Transformation of the fungicide Cyprodinil by a laccase of Trametes villosa in the presence of phenolic mediators and humic acid.
Water research, 2002Co-Authors: Ki Hoon Kang, Heekyung Park, Jerzy Dec, Jean-marc BollagAbstract:Abstract Xenobiotic chemicals can be transformed or covalently bound to humic materials by oxidoreductive enzymes present in terrestrial systems. Chemicals that are not substrates for oxidoreductive enzymes may undergo transformation in the presence of certain reactive compounds, which are often referred to as mediators. In this study, Cyprodinil, a broad-spectrum fungicide, did not show any transformation when incubated alone with a laccase from Trametes villosa . It was transformed to a significant extent, however, when a mediator was present. All of the 13 tested mediators belonged to the group of naturally occurring phenols. With some exceptions (2,6-dimethoxyphenol, syringic acid, and ferulic acid), phenols substituted with one or two methoxy groups were very effective mediators. In experiments with 14 C-labeled Cyprodinil, the radioactive label was largely associated with brown transformation products that precipitated out of the aqueous solution. As determined by mass spectrometry, the products were mixed oligomers resulting from cross-coupling between Cyprodinil and a mediator. The addition of large amounts of humic acid (HA) (400 mg/L) to the reaction mixtures involving the most effective mediators reduced Cyprodinil transformation (42.6–68.6%) by 12–48%, probably due to an inhibitory effect. The inhibition decreased with decreasing concentration of HA. The addition of HA (400 mg/L) to the reaction mixtures involving the least effective mediators or no mediators (control) enhanced Cyprodinil transformation (0.3–17.6%) by 2.9–17.1%, probably as a result of binding to HA.
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Analysis of Soil-Bound Residues of 13C-Labeled Fungicide Cyprodinil by NMR Spectroscopy
Environmental Science & Technology, 1997Co-Authors: Jerzy Dec, Konrad Haider, Alan J. Benesi, V. Rangaswamy, Andreas Schäffer, Udo Plücken, Jean-marc BollagAbstract:13C-NMR spectroscopy was applied to the evaluation of soil-bound residues of the fungicide Cyprodinil (4-cyclopropyl- 6-methyl-2-phenylaminopyrimidine). A mixture of the 13C- and 14C-labeled fungicide was used to obtain structural information as well as information on the quantitative distribution in the various fractions. Bound residues were accumulated by a 6-month incubation of the labeled compound with a clay loamy soil. Depending on the concentration of [13C]Cyprodinil (500, 250, 80, and 3 mg/kg), binding ranged from 18% to 54% of the initial radioactivity. After methanol extraction of soil (10 g dry weight) treated with 500 mg/kg (5.0 mg) of the fungicide, the amount of unextracted bound material was equivalent to 0.9 mg of 13C-labeled Cyprodinil. Upon fractionation, 0.21 mg of the bound fungicide was found in the dialyzed humic acid, 0.13 mg in fulvic acid (after extraction with CH2Cl2), and 0.24 mg in humin. The methylene chloride extract from fulvic acid mainly contained unchanged Cyprodinil (0.2...
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Formation of Soil-Bound Residues of Cyprodinil and Their Plant Uptake
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Jerzy Dec, Konrad Haider, V. Rangaswamy, Andreas Schäffer, Errol Fernandes, Jean-marc BollagAbstract:The fungicide Cyprodinil [4-cyclopropyl-6-methyl-2-(phenylamino)pyrimidine] labeled with 14C in either the phenyl or the pyrimidyl ring was incubated with four different soils under various conditions to evaluate the formation of bound residues and their subsequent plant uptake. About 60% of the initially applied radioactivity was bound to nonsterile soils within 90−180 days, whereas negligible binding was observed under sterile and anaerobic conditions. More binding was observed at higher soil pH, cation exchange capacity, and organic carbon and nitrogen contents. When spring barley was grown in the methanol-extracted soil, the plant uptake of bound residues amounted to about 0.2% for the phenyl label and 1.2% for the pyrimidyl label. The difference indicated that the pyrimidyl moiety was detached from the Cyprodinil molecule and taken up more readily. Keywords: Bound residues; plant uptake; Cyprodinil; bioavailability; barley; fungicide
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Use of a Silylation Procedure and 13C-NMR Spectroscopy To Characterize Bound and Sequestered Residues of Cyprodinil in Soil
Environmental Science & Technology, 1997Co-Authors: Jerzy Dec, Konrad Haider, Andreas Schäffer, Errol Fernandes, Jean-marc BollagAbstract:Soil-bound residues of the fungicide Cyprodinil (4-cyclopropyl-6-methyl-2-phenylaminopyrimidine), which was labeled with 13C and 14C either in the phenyl ring or the pyrimidyl ring, were analyzed by a silylation procedure and 13C-NMR spectroscopy. After a 6-month incubation of soil with 3 or 500 ppm Cyprodinil, bound residues amounted to about 50% and 18% of the initial radioactivity, respectively. The isolated humic acid fraction and the NaOH-extracted soil (the humin fraction) were suspended in chloroform and silylated by overnight shaking with trimethylchlorosilane. Analysis of the silylated extracts by 13C-NMR revealed that the formation of soil-bound residues in the 500 ppm samples involved: (1) sequestration of the unaltered or slightly altered fungicide in the humin fraction and (2) cleavage of the Cyprodinil molecule between the aromatic rings followed by covalent binding of the separated moieties to humic acid. The sequestered fungicide (phenyl label) generated triplet NMR signals at 121.0, 125....
Anthony P. Keinath - One of the best experts on this subject based on the ideXlab platform.
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Premix Fungicides That Reduce Development of Fruiting Bodies But Not Leaf Lesions by Stagonosporopsis citrulli on Watermelon Leaves in the Field.
Plant disease, 2021Co-Authors: Anthony P. KeinathAbstract:Fungicide applications are the main method to manage gummy stem blight on watermelon (Citrullus lanatus) and other cucurbits, but it is unknown whether fungicides affect development of leaf lesions or fruiting bodies by Stagonosporopsis citrulli. Cyprodinil plus fludioxonil (Switch), Cyprodinil plus difenoconazole (Inspire Super), Cyprodinil (Vangard), fludioxonil (Cannonball), and difenoconazole (Inspire) were applied to watermelon in rotation with chlorothalonil (Bravo) in fall 2017, 2018, and 2019. Water and chlorothalonil applied weekly served as control treatments. All fungicides reduced disease severity (percentage of leaf area diseased) and area under the disease progress curve (AUDPC) in field plots compared with water. Cyprodinil plus fludioxonil and Cyprodinil plus difenoconazole reduced disease severity and AUDPC more than chlorothalonil. Fungicides did not affect the number, diameter, expansion, or area of lesions. All fungicides reduced the number of lesions with fruiting bodies of S. citrulli compared with water (P < 0.05). Cyprodinil plus fludioxonil and Cyprodinil plus difenoconazole reduced the percentage of leaf lesions with fruiting bodies, and the diameter and area of the portions of leaf lesions covered with fruiting bodies, compared with water and chlorothalonil. Premix fungicides containing Cyprodinil reduced fruiting body formation by S. citrulli, which may partially explain their efficacy in managing gummy stem blight.
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Premix Fungicides that Reduce Development of Fruiting Bodies but not Leaf Lesions by Stagonosporopsis citrulli on Watermelon Leaves in the Field.
Plant disease, 2020Co-Authors: Anthony P. KeinathAbstract:Fungicide applications are the main method to manage gummy stem blight on watermelon (Citrullus lanatus) and other cucurbits, but it is unknown if fungicides affect development of leaf lesions or fruiting bodies by Stagonosporopsis citrulli. Cyprodinil + fludioxonil (Switch), Cyprodinil + difenoconazole (Inspire Super), Cyprodinil (Vangard), fludioxonil (Cannonball), and difenoconazole (Inspire) were applied to watermelon in rotation with chlorothalonil (Bravo) in fall 2017, 2018, and 2019. Water and chlorothalonil applied weekly served as control treatments. All fungicides reduced disease severity (percentage of leaf area diseased) and AUDPC in field plots compared to water. Cyprodinil + fludioxonil and Cyprodinil + difenoconazole reduced disease severity and AUDPC more than chlorothalonil. Fungicides did not affect the number, diameter, expansion, or area of lesions. All fungicides reduced the number of lesions with fruiting bodies of S. citrulli compared to water (P < 0.05). Cyprodinil + fludioxonil and Cyprodinil + difenoconazole reduced the percentage of leaf lesions with fruiting bodies, and the diameter and area of the portions of leaf lesions covered with fruiting bodies, compared to water and chlorothalonil. Premix fungicides containing Cyprodinil reduced fruiting body formation by S. citrulli, which may partially explain their efficacy in managing gummy stem blight.
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baseline sensitivity of didymella bryoniae to Cyprodinil and fludioxonil and field efficacy of these fungicides against isolates resistant to pyraclostrobin and boscalid
Plant Disease, 2015Co-Authors: Anthony P. KeinathAbstract:To prevent yield reductions from gummy stem blight, fungicides often must be applied to watermelon (Citrullus lanatus) and muskmelon (Cucumis melo). Didymella bryoniae, the ascomycete fungus that causes gummy stem blight, is resistant to thiophanate-methyl, quinone-outside inhibitors (QoI), boscalid, and penthiopyrad. In place of these fungicides, premixtures of Cyprodinil and fludioxonil (Switch 62.5WG) or Cyprodinil and difenoconazole (Inspire Super 2.82SC) are used. The objectives of this study were to examine baseline isolates of D. bryoniae for sensitivity to Cyprodinil and fludioxonil and to determine the efficacy of Cyprodinil-fludioxonil and Cyprodinil-difenoconazole against isolates resistant to QoI fungicides and boscalid. Colony diameters of 146 isolates of D. bryoniae collected in South Carolina and other U.S. states prior to 2008 were measured on glucose minimal medium amended with Cyprodinil or fludioxonil. Mean effective concentration values that reduced relative colony diameter by 50% were...
Burkhard Schmidt - One of the best experts on this subject based on the ideXlab platform.
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suspension cultures
2016Co-Authors: Inken Bringmann, Burkhard SchmidtAbstract:Characterization of the bound residues of the fungicide Cyprodinil formed in plant cel
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Investigation on the Chemical Structure of Nonextractable Residues of the Fungicide Cyprodinil in Spring Wheat Using 13C-C1-Phenyl-Cyprodinil on 13C-Depleted Plants—An Alternative Approach to Investigate Nonextractable Residues
Journal of environmental science and health. Part. B Pesticides food contaminants and agricultural wastes, 2004Co-Authors: Tanya Ertunç, Burkhard Schmidt, Holger Kühn, Marco Bertmer, Andreas SchäfferAbstract:13C-labelled Cyprodinil was applied on 13C-depleted wheat plants with 27-fold field application rate. A control experiment applying same amounts of 14C-Cyprodinil showed that main portions of the residues were detected in the cellulose (15% NER), hemicellulose (28.3% NER), and lignin fraction (23.3% NER). 16.7% were detected in water soluble polymers, 6% in both, pectin and protein fraction, and 4% in the starch containing fraction. Free Cyprodinil was detectable by TLC in all fractions except lignin. A direct characterization of the residues in vivo by CP-MAS was not successful. Cell wall fractions were further analysed by liquid state NMR to determine the structure of the mobilized highly polymer/polar residues: Within lignin, where most of the residues were located at field application rate, neither intact Cyprodinil nor its metabolites could not be detected. The 13C-label introduced was probably incorporated in the polymer as natural lignin monomers and thus are not considered as bound residues according to IUPAC definition.
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Characterization of the bound residues of the fungicide Cyprodinil formed in plant cell suspension cultures of wheat.
Pest management science, 2003Co-Authors: Melanie Sapp, Andreas Schäffer, Tanya Ertunç, Inken Bringmann, Burkhard SchmidtAbstract:The non-extractable residues of the fungicide Cyprodinil formed in heterotrophic cell suspension cultures of wheat were studied by application of (2-pyrimidyl- 14 C) or (2-pyrimidyl- 13 C)Cyprodinil. The main objective was to examine whether solid-state and liquid 13 C NMR spectroscopy can be used to examine plant bound residues of pesticides. For 14 C experiments, wheat suspensions grown on glucose as carbon source were treated with 10mglitre −1 of 14 C-Cyprodinil. After incubation for 12days, 20% of applied 14 C was detected as non-extractable residues. The cell debris were treated with 0.1 M HCl (reflux), 1.0 M HCl (reflux), buffer, or 2 M NaOH (50 ◦ C) ;B j¨ orkman lignin and acidolysis lignin fractions were also prepared from the debris. Radioactivity liberated and solubilized by these procedures was examined by thin-layer chromatography and high-performance liquid chromatography. The results showed that Cyprodinil and primary metabolites contributed to the fungicide's bound residues. Most of the residues (12% of applied 14 C) remained associated with polar or polymeric/oligomeric endogenous cell materials in a stable manner. For the study with 13 C-Cyprodinil, wheat suspensions were cultivated on 13 C-depleted glucose for four growth cycles, resulting in maximum 13 C depletion of the natural cell components to about 0.10%. During the fourth cycle, 13 C-labelled Cyprodinil was applied, and cells were incubated (12days). Cell debris was prepared and examined by solid-state 13 C NMR spectroscopy. Debris was then treated as described above in the 14 C experiment. Solubilized fractions were analyzed by liquid 13 CN MR spectroscopy. However, none of the 13 C NMR spectra recorded gave utilizable or unambiguous results, and all exhibited large inconsistencies, especially concerning the data from the conventional 14 C experiment. 2003 Society of Chemical Industry
Jerzy Dec - One of the best experts on this subject based on the ideXlab platform.
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Transformation of the fungicide Cyprodinil by a laccase of Trametes villosa in the presence of phenolic mediators and humic acid.
Water research, 2002Co-Authors: Ki Hoon Kang, Heekyung Park, Jerzy Dec, Jean-marc BollagAbstract:Abstract Xenobiotic chemicals can be transformed or covalently bound to humic materials by oxidoreductive enzymes present in terrestrial systems. Chemicals that are not substrates for oxidoreductive enzymes may undergo transformation in the presence of certain reactive compounds, which are often referred to as mediators. In this study, Cyprodinil, a broad-spectrum fungicide, did not show any transformation when incubated alone with a laccase from Trametes villosa . It was transformed to a significant extent, however, when a mediator was present. All of the 13 tested mediators belonged to the group of naturally occurring phenols. With some exceptions (2,6-dimethoxyphenol, syringic acid, and ferulic acid), phenols substituted with one or two methoxy groups were very effective mediators. In experiments with 14 C-labeled Cyprodinil, the radioactive label was largely associated with brown transformation products that precipitated out of the aqueous solution. As determined by mass spectrometry, the products were mixed oligomers resulting from cross-coupling between Cyprodinil and a mediator. The addition of large amounts of humic acid (HA) (400 mg/L) to the reaction mixtures involving the most effective mediators reduced Cyprodinil transformation (42.6–68.6%) by 12–48%, probably due to an inhibitory effect. The inhibition decreased with decreasing concentration of HA. The addition of HA (400 mg/L) to the reaction mixtures involving the least effective mediators or no mediators (control) enhanced Cyprodinil transformation (0.3–17.6%) by 2.9–17.1%, probably as a result of binding to HA.
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Analysis of Soil-Bound Residues of 13C-Labeled Fungicide Cyprodinil by NMR Spectroscopy
Environmental Science & Technology, 1997Co-Authors: Jerzy Dec, Konrad Haider, Alan J. Benesi, V. Rangaswamy, Andreas Schäffer, Udo Plücken, Jean-marc BollagAbstract:13C-NMR spectroscopy was applied to the evaluation of soil-bound residues of the fungicide Cyprodinil (4-cyclopropyl- 6-methyl-2-phenylaminopyrimidine). A mixture of the 13C- and 14C-labeled fungicide was used to obtain structural information as well as information on the quantitative distribution in the various fractions. Bound residues were accumulated by a 6-month incubation of the labeled compound with a clay loamy soil. Depending on the concentration of [13C]Cyprodinil (500, 250, 80, and 3 mg/kg), binding ranged from 18% to 54% of the initial radioactivity. After methanol extraction of soil (10 g dry weight) treated with 500 mg/kg (5.0 mg) of the fungicide, the amount of unextracted bound material was equivalent to 0.9 mg of 13C-labeled Cyprodinil. Upon fractionation, 0.21 mg of the bound fungicide was found in the dialyzed humic acid, 0.13 mg in fulvic acid (after extraction with CH2Cl2), and 0.24 mg in humin. The methylene chloride extract from fulvic acid mainly contained unchanged Cyprodinil (0.2...
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Formation of Soil-Bound Residues of Cyprodinil and Their Plant Uptake
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Jerzy Dec, Konrad Haider, V. Rangaswamy, Andreas Schäffer, Errol Fernandes, Jean-marc BollagAbstract:The fungicide Cyprodinil [4-cyclopropyl-6-methyl-2-(phenylamino)pyrimidine] labeled with 14C in either the phenyl or the pyrimidyl ring was incubated with four different soils under various conditions to evaluate the formation of bound residues and their subsequent plant uptake. About 60% of the initially applied radioactivity was bound to nonsterile soils within 90−180 days, whereas negligible binding was observed under sterile and anaerobic conditions. More binding was observed at higher soil pH, cation exchange capacity, and organic carbon and nitrogen contents. When spring barley was grown in the methanol-extracted soil, the plant uptake of bound residues amounted to about 0.2% for the phenyl label and 1.2% for the pyrimidyl label. The difference indicated that the pyrimidyl moiety was detached from the Cyprodinil molecule and taken up more readily. Keywords: Bound residues; plant uptake; Cyprodinil; bioavailability; barley; fungicide
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Use of a Silylation Procedure and 13C-NMR Spectroscopy To Characterize Bound and Sequestered Residues of Cyprodinil in Soil
Environmental Science & Technology, 1997Co-Authors: Jerzy Dec, Konrad Haider, Andreas Schäffer, Errol Fernandes, Jean-marc BollagAbstract:Soil-bound residues of the fungicide Cyprodinil (4-cyclopropyl-6-methyl-2-phenylaminopyrimidine), which was labeled with 13C and 14C either in the phenyl ring or the pyrimidyl ring, were analyzed by a silylation procedure and 13C-NMR spectroscopy. After a 6-month incubation of soil with 3 or 500 ppm Cyprodinil, bound residues amounted to about 50% and 18% of the initial radioactivity, respectively. The isolated humic acid fraction and the NaOH-extracted soil (the humin fraction) were suspended in chloroform and silylated by overnight shaking with trimethylchlorosilane. Analysis of the silylated extracts by 13C-NMR revealed that the formation of soil-bound residues in the 500 ppm samples involved: (1) sequestration of the unaltered or slightly altered fungicide in the humin fraction and (2) cleavage of the Cyprodinil molecule between the aromatic rings followed by covalent binding of the separated moieties to humic acid. The sequestered fungicide (phenyl label) generated triplet NMR signals at 121.0, 125....
Andreas Schäffer - One of the best experts on this subject based on the ideXlab platform.
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Investigation on the Chemical Structure of Nonextractable Residues of the Fungicide Cyprodinil in Spring Wheat Using 13C-C1-Phenyl-Cyprodinil on 13C-Depleted Plants—An Alternative Approach to Investigate Nonextractable Residues
Journal of environmental science and health. Part. B Pesticides food contaminants and agricultural wastes, 2004Co-Authors: Tanya Ertunç, Burkhard Schmidt, Holger Kühn, Marco Bertmer, Andreas SchäfferAbstract:13C-labelled Cyprodinil was applied on 13C-depleted wheat plants with 27-fold field application rate. A control experiment applying same amounts of 14C-Cyprodinil showed that main portions of the residues were detected in the cellulose (15% NER), hemicellulose (28.3% NER), and lignin fraction (23.3% NER). 16.7% were detected in water soluble polymers, 6% in both, pectin and protein fraction, and 4% in the starch containing fraction. Free Cyprodinil was detectable by TLC in all fractions except lignin. A direct characterization of the residues in vivo by CP-MAS was not successful. Cell wall fractions were further analysed by liquid state NMR to determine the structure of the mobilized highly polymer/polar residues: Within lignin, where most of the residues were located at field application rate, neither intact Cyprodinil nor its metabolites could not be detected. The 13C-label introduced was probably incorporated in the polymer as natural lignin monomers and thus are not considered as bound residues according to IUPAC definition.
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Characterization of the bound residues of the fungicide Cyprodinil formed in plant cell suspension cultures of wheat.
Pest management science, 2003Co-Authors: Melanie Sapp, Andreas Schäffer, Tanya Ertunç, Inken Bringmann, Burkhard SchmidtAbstract:The non-extractable residues of the fungicide Cyprodinil formed in heterotrophic cell suspension cultures of wheat were studied by application of (2-pyrimidyl- 14 C) or (2-pyrimidyl- 13 C)Cyprodinil. The main objective was to examine whether solid-state and liquid 13 C NMR spectroscopy can be used to examine plant bound residues of pesticides. For 14 C experiments, wheat suspensions grown on glucose as carbon source were treated with 10mglitre −1 of 14 C-Cyprodinil. After incubation for 12days, 20% of applied 14 C was detected as non-extractable residues. The cell debris were treated with 0.1 M HCl (reflux), 1.0 M HCl (reflux), buffer, or 2 M NaOH (50 ◦ C) ;B j¨ orkman lignin and acidolysis lignin fractions were also prepared from the debris. Radioactivity liberated and solubilized by these procedures was examined by thin-layer chromatography and high-performance liquid chromatography. The results showed that Cyprodinil and primary metabolites contributed to the fungicide's bound residues. Most of the residues (12% of applied 14 C) remained associated with polar or polymeric/oligomeric endogenous cell materials in a stable manner. For the study with 13 C-Cyprodinil, wheat suspensions were cultivated on 13 C-depleted glucose for four growth cycles, resulting in maximum 13 C depletion of the natural cell components to about 0.10%. During the fourth cycle, 13 C-labelled Cyprodinil was applied, and cells were incubated (12days). Cell debris was prepared and examined by solid-state 13 C NMR spectroscopy. Debris was then treated as described above in the 14 C experiment. Solubilized fractions were analyzed by liquid 13 CN MR spectroscopy. However, none of the 13 C NMR spectra recorded gave utilizable or unambiguous results, and all exhibited large inconsistencies, especially concerning the data from the conventional 14 C experiment. 2003 Society of Chemical Industry
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Analysis of Soil-Bound Residues of 13C-Labeled Fungicide Cyprodinil by NMR Spectroscopy
Environmental Science & Technology, 1997Co-Authors: Jerzy Dec, Konrad Haider, Alan J. Benesi, V. Rangaswamy, Andreas Schäffer, Udo Plücken, Jean-marc BollagAbstract:13C-NMR spectroscopy was applied to the evaluation of soil-bound residues of the fungicide Cyprodinil (4-cyclopropyl- 6-methyl-2-phenylaminopyrimidine). A mixture of the 13C- and 14C-labeled fungicide was used to obtain structural information as well as information on the quantitative distribution in the various fractions. Bound residues were accumulated by a 6-month incubation of the labeled compound with a clay loamy soil. Depending on the concentration of [13C]Cyprodinil (500, 250, 80, and 3 mg/kg), binding ranged from 18% to 54% of the initial radioactivity. After methanol extraction of soil (10 g dry weight) treated with 500 mg/kg (5.0 mg) of the fungicide, the amount of unextracted bound material was equivalent to 0.9 mg of 13C-labeled Cyprodinil. Upon fractionation, 0.21 mg of the bound fungicide was found in the dialyzed humic acid, 0.13 mg in fulvic acid (after extraction with CH2Cl2), and 0.24 mg in humin. The methylene chloride extract from fulvic acid mainly contained unchanged Cyprodinil (0.2...
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Formation of Soil-Bound Residues of Cyprodinil and Their Plant Uptake
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Jerzy Dec, Konrad Haider, V. Rangaswamy, Andreas Schäffer, Errol Fernandes, Jean-marc BollagAbstract:The fungicide Cyprodinil [4-cyclopropyl-6-methyl-2-(phenylamino)pyrimidine] labeled with 14C in either the phenyl or the pyrimidyl ring was incubated with four different soils under various conditions to evaluate the formation of bound residues and their subsequent plant uptake. About 60% of the initially applied radioactivity was bound to nonsterile soils within 90−180 days, whereas negligible binding was observed under sterile and anaerobic conditions. More binding was observed at higher soil pH, cation exchange capacity, and organic carbon and nitrogen contents. When spring barley was grown in the methanol-extracted soil, the plant uptake of bound residues amounted to about 0.2% for the phenyl label and 1.2% for the pyrimidyl label. The difference indicated that the pyrimidyl moiety was detached from the Cyprodinil molecule and taken up more readily. Keywords: Bound residues; plant uptake; Cyprodinil; bioavailability; barley; fungicide
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Use of a Silylation Procedure and 13C-NMR Spectroscopy To Characterize Bound and Sequestered Residues of Cyprodinil in Soil
Environmental Science & Technology, 1997Co-Authors: Jerzy Dec, Konrad Haider, Andreas Schäffer, Errol Fernandes, Jean-marc BollagAbstract:Soil-bound residues of the fungicide Cyprodinil (4-cyclopropyl-6-methyl-2-phenylaminopyrimidine), which was labeled with 13C and 14C either in the phenyl ring or the pyrimidyl ring, were analyzed by a silylation procedure and 13C-NMR spectroscopy. After a 6-month incubation of soil with 3 or 500 ppm Cyprodinil, bound residues amounted to about 50% and 18% of the initial radioactivity, respectively. The isolated humic acid fraction and the NaOH-extracted soil (the humin fraction) were suspended in chloroform and silylated by overnight shaking with trimethylchlorosilane. Analysis of the silylated extracts by 13C-NMR revealed that the formation of soil-bound residues in the 500 ppm samples involved: (1) sequestration of the unaltered or slightly altered fungicide in the humin fraction and (2) cleavage of the Cyprodinil molecule between the aromatic rings followed by covalent binding of the separated moieties to humic acid. The sequestered fungicide (phenyl label) generated triplet NMR signals at 121.0, 125....
