piperidines and fenpropidine

As a chiral piperidine fungicide, fenpropidin has been widely used to control plant diseases. However, there are rare studies that have investigated fenpropidin at the enantiomer level. In this study, the single-factor analysis combined with a Box-Behnken design was used to obtain the optimal enantio-separation parameters of the fenpropidin enantiomers on ultra-performance liquid chromatography-tandem mass spectrometry. The absolute configuration of two fenpropidin enantiomers was confirmed for the first time using electron circular dichroism and optical activity. On the Lux cellulose-3 column,

Topics: Cellulose; Chromatography, High Pressure Liquid; Chromatography, Liquid; Fungicides, Industrial; Molecular Docking Simulation; Piperidines; Soil; Soil Pollutants; Stereoisomerism; Tandem Mass Spectrometry

The cardiac embryonic stem cell test (ESTc) is an in vitro embryotoxicity screen which uses cardiomyocyte formation as the main differentiation route. Studies are ongoing into whether an improved specification of the biological domain can broaden the applicability of the test, e.g. to discriminate between structurally similar chemicals by measuring expression of dedicated gene transcript biomarkers. We explored this with two chemical classes: morpholines (tridemorph; fenpropimorph) and piperidines (fenpropidin; spiroxamine). These compounds cause embryotoxicity in rat such as cleft palate. This malformation can be linked to interference with retinoic acid balance, neural crest (NC) cell migration, or cholesterol biosynthesis. Also neural differentiation within the ESTc was explored in relation to these compounds. Gene transcript expression of related biomarkers were measured at low and high concentrations on differentiation day 4 (DD4) and DD10. All compounds showed stimulating effects on the cholesterol biosynthesis related marker Msmo1 after 24 h exposure and tridemorph showed inhibition of Cyp26a1 which codes for one of the enzymes that metabolises retinoic acid. A longer exposure duration enhanced expression levels for differentiation markers for cardiomyocytes (Nkx2-5; Myh6) and neural cells (Tubb3) on DD10. This readout gave additional mechanistic insight which enabled previously unavailable in vitro discrimination between the compounds, showing the practical utility of specifying the biological domain of the ESTc.

Topics: Animals; Cell Differentiation; Cells, Cultured; Gene Expression Regulation, Developmental; Gene Regulatory Networks; Homeobox Protein Nkx-2.5; Mice; Mixed Function Oxygenases; Morpholines; Mouse Embryonic Stem Cells; Myocytes, Cardiac; Myosin Heavy Chains; Piperidines; Retinoic Acid 4-Hydroxylase; Risk Assessment; Spiro Compounds; Time Factors; Toxicity Tests; Tubulin

The residue levels and dissipation rate of fenpropidin in wheat and soil were investigated by LC-MS/MS and GC-MS, respectively. The dissipation rates of fenpropidin were described using first-order kinetics and its half-life ranged from 3.1 to 3.3 days in wheat plants and 13.4-16.5 days in soils. During harvest time, the terminal residues of fenpropidin in wheat were below the EUs maximum residue limit (MRL, 0.5 mg kg(-1)) when collected 20 days after the final application, which suggested that the use of this fungicide was safe for humans. The residues persistence varied between two geographically separated experimental sites, indicating that it might be influenced by climate, soil properties and growth dilution factor. These results would be helpful in setting MRL guidance of fenpropidin in wheat in China.

Topics: China; Climate; Fungicides, Industrial; Half-Life; Humans; Models, Chemical; Pesticide Residues; Piperidines; Soil; Soil Pollutants; Tandem Mass Spectrometry; Triticum

Fusarium graminearum, the causal agent of wheat head blight, shows intrinsic resistance to amine fungicides. It is commonly accepted that the amines target sterol C-14 reductase and sterol Δ(8)-Δ(7) isomerase of ergosterol biosynthesis, encoded by the genes ERG24 and ERG2, respectively. Analysis of the genome sequence of F. graminearum revealed that the fungus contains two paralogous FgERG24 genes (FgERG24A and FgERG24B), which are homologous to the ERG24 of Saccharomyces cerevisiae. In this study, we disrupted FgERG24A and FgERG24B in F. graminearum. Compared to the wild-type strain HN9-1, FgERG24A and FgERG24B deletion mutants did not show recognizable phenotypic changes in mycelial growth on potato dextrose agar or in virulence on wheat heads. HPLC analysis showed that the amount of ergosterol in FgERG24A or FgERG24B deletion mutants was not significantly different from that in the wild-type strain. These results indicate that neither of the two genes is essential for growth, pathogenicity or ergosterol biosynthesis in F. graminearum. FgERG24B deletion mutants exhibited significantly increased sensitivity to amine fungicides, including tridemorph, fenpropidin and spiroxamine, but not to non-amine fungicides. In contrast, FgERG24A deletion mutants did not show changed sensitivity to any amine tested. The resistance of the FgERG24B deletion mutant to amines was restored by genetic complementation of the mutant with wild-type FgERG24B. These results indicate that FgERG24B controls the intrinsic resistance of F. graminearum to amines. The finding of this study provides new insights into amine resistance in filamentous fungi.

Topics: Amines; Drug Resistance, Fungal; Ergosterol; Fungicides, Industrial; Fusarium; Gene Deletion; Microbial Sensitivity Tests; Morpholines; Oxidoreductases; Piperidines; Plant Diseases; Spiro Compounds; Steroid Isomerases; Triticum

The ergosterol biosynthesis-inhibiting (EBI) fungicide prochloraz can enhance the effect of other pesticides in a range of animal species. Approximately 50% of the fungicides used in Denmark are EBI fungicides. Hence, if they all have synergising potential, a risk assessment of pesticide mixtures based on additivity might not suffice. This study investigates the synergising potential of six different EBI fungicides representing the imidazoles (prochloraz), the triazoles (epoxiconazole, propiconazole and tebuconazole), the piperidines (fenpropidin) and the morpholines (fenpropimorph) together with the pyrethroid insecticide alpha-cypermethrin.. Tests were made on the aquatic crustacean Daphnia magna. Mixtures of each of the fungicides were tested together with the insecticide both at a 50:50% effect mixture ratio and, subsequently, in a ray design including five mixture ratios. The results were tested against the concentration addition reference model using dose-response surface analyses.. The results of the binary dose-response surface studies showed that mixtures with prochloraz increased toxicity up to 12-fold compared with what was expected using the reference model concentration addition (CA). Epoxiconazole and propiconazole enhanced toxicity up to six and sevenfold, respectively. Fenpropimorph showed antagonism, whilst mixtures with tebuconazole and fenpropidin did not deviate statistically from CA.. Hence, it can be concluded that both imidazoles and some, but not all, triazoles can enhance the effect of a pyrethroid insecticide towards D. magna substantially. Epoxiconazole and propiconazole are often sprayed out together with pyrethroids in tank mixtures. The extent to which this might create unforeseen ecological problems is discussed.

Topics: Animals; Daphnia; Dose-Response Relationship, Drug; Drug Synergism; Fungicides, Industrial; Imidazoles; Insecticides; Morpholines; Piperidines; Pyrethrins; Toxicity Tests; Triazoles; Water Pollutants, Chemical

Few data sets of pesticide volatilization from plants at the field scale are available. In this work, we report measurements of fenpropidin and chlorothalonil volatilization on a wheat field using the aerodynamic gradient (AG) method and an inverse dispersion modeling approach (using the FIDES model). Other data necessary to run volatilization models are also reported: measured application dose, crop interception, plant foliage residue, upwind concentrations, and meteorological conditions. The comparison of the AG and inverse modeling methods proved the latter to be reliable and hence suitable for estimating volatilization rates with minimized costs. Different diurnal/nocturnal volatilization patterns were observed: fenpropidin volatilization peaked on the application day and then decreased dramatically, while chlorothalonil volatilization remained fairly stable over a week-long period. Cumulated emissions after 31 h reached 3.5 g ha(-1) and 5 g ha(-1), respectively (0.8% and 0.6% of the theoretical application dose). A larger difference in volatilization rates was expected given differences in vapor pressure, and for fenpropidin, volatilization should have continued given that 80% of the initial amount remained on plant foliage for 6 days. We thus ask if vapor pressure alone can accurately estimate volatilization just after application and then question the state of foliar residue. We identified adsorption, formulation, and extraction techniques as relevant explanations.

Topics: Agriculture; Air; Atmosphere; Friction; Fungicides, Industrial; Meteorological Concepts; Models, Chemical; Nitriles; Pesticide Residues; Piperidines; Plant Leaves; Solutions; Triticum; Vapor Pressure; Volatilization

Airborne pesticides can be detected near to recently-treated arable fields for a period of days following the application. Identifying the source of such pesticides is important in developing predictive models for use in exposure and risk assessments. Previous work showed levels of pesticide in the air that were higher than expected for a low-vapour-pressure active ingredient, epoxiconazole, and comparable with an active ingredient of a significantly higher vapour pressure, fenpropidin. It was possible that the measured concentrations could be attributed to 'dust' particles emitted from the crop, either biological material contaminated with pesticide or solid dried deposits of active ingredient and other formulation components. A second experiment was therefore undertaken to measure airborne concentrations of the same active ingredients and to determine whether some or all of the measured airborne pesticide could be attributed to particles, using a Marple personal cascade impactor, which collects particles in the range 0.3 - 50 microm. Such samplers are not optimised to give good sampling efficiencies under the proposed field conditions, so some initial tests were undertaken in the Silsoe wind tunnel to assess its ability to sample particles in an air flow. In the subsequent field trial, a 192 m square plot in a commercially established winter cereal crop was sprayed with a tank mix of commercial formulations of epoxiconazole and fenpropidin. Measurements of airborne pesticides were made for 24 hours following the application with suction samplers attached to tenax tubes to evaluate vapour concentrations and with the cascade impactor to determine whether contaminated airborne particles were present. The concentrations of pesticide measured with the tenax tubes were significantly higher than the particulate component detected on the cascade impactor plates and it is therefore it was very unlikely that there was a significant contribution from pesticide-laden particles to the airborne concentration. Although it is clear that under these particular experimental conditions, airborne contaminated particles were not detected in significant quantities after the application, it is possible that this could occur under different circumstances, such as during pollen release or harvest.

Topics: Aerosols; Agriculture; Air Pollutants; Dust; Edible Grain; Epoxy Compounds; Fungicides, Industrial; Particle Size; Piperidines; Time Factors; Triazoles; Wind

The absorption spectra of five pesticides, namely 2,4-dichloro-phenoxy acetic acid (2,4-D), cymoxanil, fenpropidin, isoproturon and pyrimethanil, have been measured in aqueous solution using a set-up consisting of two parallel absorption cells coupled to a CCD detector. The absolute values of their molar absorptivity coefficients epsilon were determined in the wavelength-range 240-344 nm with a deuterium-lamp at room temperature (298+/-2 K). Using the Beer-Lambert law, values of epsilon were also determined at 253.7 nm with a Hg-Lamp: epsilon = 145+/-14 for 2,4-D, epsilon = 7940+/-920 for cymoxanil, epsilon = 196+/-14 for fenpropidin, epsilon = 7330+/-880 for isoproturon, epsilon = 13200+/-1400 for pyrimethanil (in units of M(-1) cm(-1)). The quoted errors correspond to 2 sigma obtained from the least square fit analysis and the estimated systematic error of 5% due to the uncertainties in aqueous concentrations. For all the studied compounds, the absorbances measured were lower than 2.3 and did not exhibit any deviation from the Beer-Lambert's law. Our experimental data are discussed and compared to UV spectra of similar molecules when such data were available in the literature. Based on their UV spectra and the calculated fractions of these pesticides in the aqueous phase, their direct photolysis under sunlight environment could occur, except may be for fenpropidin, either in water surfaces or in aqueous droplets contained in the atmospheric clouds.

Topics: 2,4-Dichlorophenoxyacetic Acid; Acetamides; Pesticides; Phenylurea Compounds; Piperidines; Pyrimidines; Solutions; Spectrophotometry, Ultraviolet; Water

Acute static bioassays were performed using three freshwater invertebrate species (the oligochaete Lumbriculus variegatus, the fingernail clam Sphaerium corneum and the larvae Chironomus riparius) exposed separately to a variety of 14C radiolabelled contaminants. The aim of this work was to investigate if the chemicals remained as parent compounds after the treatments. Chemicals used were 2,4-dichlorophenol; 2,4,5-trichlorophenol; pentachlorophenol; pyrene; Fenpropidin, and Trifluralin. Homogenates of the whole body tissue of each organism were prepared and total radioactivity was measured. Contaminants were then extracted into organic solvents and analysed by high-pressure liquid chromatography techniques. Chromatograms showed that most of the substances extracted were present as parent compounds in S. corneum and in L. variegatus. In contrast, for C. riparius a low proportion of the chemicals was recovered as parent compounds. These results suggest that different metabolic processes could take place in the different species.

Topics: Animals; Biological Assay; Biotransformation; Bivalvia; Carbon Radioisotopes; Chlorophenols; Chromatography, High Pressure Liquid; Fresh Water; Invertebrates; Larva; Oligochaeta; Pentachlorophenol; Piperidines; Pyrenes; Trifluralin; Water Pollutants, Chemical

We have transformed Saccharomyces cerevisiae with a genomic library contained in the replicative vector pFL44. The resulting transformants were screened for resistance to fenpropidin, a specific inhibitor of sterol 14-reductase. A plasmid was isolated that transformed yeast both to resistance to fenpropidin and to an increased specific activity of sterol 14-reductase. Sterol analysis of transformed cells grown in the presence of increasing concentrations of the inhibitor confirmed that resistance was a consequence of over-production of sterol 14-reductase. By chromosomal gene disruption, we have, for the first time, constructed yeast strains defective in sterol 14-reductase. As expected, since yeast in unable to take up sterols in aerobiosis, the disrupted strains do not grow in the presence of oxygen, even if exogenous sterols are supplied. However, disrupted cells grow in anaerobiosis with exogenous oleic acid and ergosterol supplements. They also grow in aerobiosis if they bear an additional mutation allowing sterol uptake. In this last growth condition the cells require a "sparking" ergosterol supplementation (25 nM) and accumulate ignosterol (ergosta-8,14-dienol) as the end-product of the sterol pathway. These results reveal that ignosterol is not obviously toxic to yeast membranes and strongly suggest that the molecular basis of the antifungal-activity morpholine and piperidine is directly related to the specific inhibition of ergosterol formation.

Topics: Cloning, Molecular; Drug Resistance, Microbial; Ergosterol; Genes, Fungal; Mutagenesis, Site-Directed; Oxidoreductases; Piperidines; Saccharomyces cerevisiae; Transformation, Genetic

An enzyme assay for inhibitors of fungal sterol delta 14-reductase employing isocratic reversed-phase high-performance liquid chromatography is described. A Hypersil 5-microns octadecylsilyl (ODS) column (250 mm x 4.6 mm I.D.) was used and a mobile phase consisting of methanol-water-ethanol (86:4:10, v/v) was pumped at a flow-rate of 1.5 ml/min. Typical analysis times were 15 min. Using [4-14C]ignosterol as a substrate and an enzyme preparation from Saccharomyces cerevisiae, this method was used to compare the inhibition of sterol delta 14-reductase by the fungicides fenpropidin and fenpropimorph with three N-substituted 8-azadecaline compounds.

Topics: Carbon Radioisotopes; Chromatography, High Pressure Liquid; Kinetics; Morpholines; Oxidoreductases; Piperidines; Saccharomyces cerevisiae

Cholesterol oxidase is a potentially important enzyme in steroid transformations, catalysing the conversion of 3-hydroxy-5-ene steroids to 3-keto-4-ene derivatives via a 3-keto-5-ene intermediate. Morpholine derivatives, especially fenpropimorph and tridemorph, were found to block selectively the isomerisation activity of cholesterol oxidases isolated from Nocardia erythropolis, Streptomyces sp., Pseudomonas testosteroni and Schizophyllum commune. These enzymes differ strongly in physical characteristics and catalytic behaviour. The effectiveness of the inhibitors varied with the cholesterol oxidase tested. Fenpropimorph was most effective with each of the 4 enzymes, 50 mg/l inhibiting about 50% of the enzyme activity. Inhibition was instantaneous and followed a reversible competitive mechanism in Streptomyces sp. and a reversible non-competitive mechanism in Nocardia erythropolis and Schizophyllum commune. An irreversible type of inhibition was observed for P. testosteroni cholesterol oxidase.

Topics: 1-Propanol; 3-Hydroxysteroid Dehydrogenases; Cholesterol Oxidase; Fungicides, Industrial; Isomerism; Kinetics; Morpholines; Nocardia; Piperidines; Pseudomonas; Schizophyllum; Streptomyces