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Stage-specific effects of the fungicide carbendazim on Sertoli cell microtubules in rat testis.

The aim of the present study is to provide a morphological explanation of carbendazim (CBZ)-induced sloughing of germ cells that occurs in a stage-specific manner. Therefore, very early alterations in the seminiferous tubule epithelium were examined histologically in the rat testis after oral administration of CBZ (400mg/kg). Gaps between the elongated and round spermatids, the first indication of germ cell sloughing (pre-sloughing), were observed in stage late VI-early VII seminiferous tubules at 90-min post-treatment. Tubulin immunoreaction in the Sertoli cells was reduced in intensity in tubules with pre-sloughing. However, electron microscopy demonstrated that there were some intact microtubules in these cells. At 120 min, sloughing was seen in stage late VI-early VII and XIII-XIV. Tubulin immunoreaction in the Sertoli cells was greatly decreased in intensity in tubules where cell sloughing was observed. Electron microscopy showed that there were few microtubules in the body region of these cells. Stages II-V and mid-VII-VIII were exempt from the sloughing effect at 180 min. These changes in microtubules were not observed in Sertoli cells that did not exhibit sloughing characteristics, regardless of the post-treatment intervals. The present results suggest that stage specificity of sloughing is due to the stage-specific susceptibility of Sertoli cell microtubules to CBZ.

Administration, Oral↗

Effects of sensitizers on the photodegradation of the systemic fungicide triadimenol.

The photochemical behaviour of triadimenol (1) under various conditions has been examined. Significant degradation is obtained only in the presence of electron-acceptor sensitizers as 9,10-dicyanoanthracene or 2,4,6-triphenylpyrylium tetrafluoroborate, and long irradiation times are required. 1H-1,2,4-Triazole (2), 4-chlorophenyl formate (3), 4-chlorophenol (4), 1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-one (5), 4-chlorophenyl 2,2-dimethylpropanoate (6) and 4-chlorobenzoic acid (7) were identified as photoproducts by NMR and GC-MS.

Fungicides, Industrial↗

Effect of a triazole fungicide on the cellulose decomposition by the soil microflora.

The effect of flutriafol on the cellulose decomposition was studied in the laboratory as a dose-response experiment using a trade marked formulation. Cellulose degradation rates were determined by the weight loss from cellulose filter disks buried in soil samples and by the CO2 evolved during batch incubation experiments. To amounts recommended for field applications and ten-fold these dosages, flutriafol did not affect the cellulose decomposition ability of the soil-microflora. Highest dosages provoked an initial inhibitory effect, followed by a stimulation in cellulolytic activity. Possible reasons for the dose-response relationship were changes in the soil microflora in favour of bacteria, indicating the importance of the persistence and repeated applications of flutriafol.

Agriculture↗

Development of an enzyme-linked immunosorbent assay for the fungicide imazalil in citrus fruits.

Imazalil has been widely used in citrus fruits such as lemons, oranges, and grapefruits. A competitive enzyme-linked immunosorbent assay (ELISA) was developed for the detection of residual imazalil in citrus fruits. A monoclonal antibody (MoAb) generated to the synthetic imazalil hapten (EIT-0073)-protein conjugate was used. This assay was applied to lemon, orange, and grapefruit matrices for an imazalil analysis. The acceptable residue level for lemons, oranges, and grapefruits in Japan is 5 ppm. The matrix interference was minimized by direct dilution of the sample homogenate. No further cleanup was needed. The detection limit for imazalil in these citrus fruits was 0.1 ng/mL. The recovery of each fortified citrus fruit sample was >81.0%. The imazalil recovery measured by the proposed ELISA was compared to the recovery determined by a conventional HPLC. A good correlation was observed between the proposed ELISA and the HPLC. This proposed ELISA would be useful for monitoring for residual imazalil.

Antibodies, Monoclonal↗

Development of a gas chromatographic method for fungicide cymoxanil analysis in dried hops.

An analytical method for detecting cymoxanil [2-cyano-N-[(ethylamino)carbonyl]-2-(methoxyimino)acetamide] residues in dried hops was developed utilizing liquid-liquid partitioning, automated gel permeation chromatography (GPC), solid phase extraction (SPE) cleanup, and gas chromatography (GC). Method validation recoveries from dried hops were 96 +/- 12, 108 +/- 11, and 136 +/- 8% over three levels of fortification (0.05, 0.5, and 1.0 ppm, respectively). The hop samples from three field sites, which were treated with cymoxanil, had residue levels ranging from 0.146 to 0.646 ppm. The detection limit and the quantitation limit of the method developed in the present study were 0.022 and 0.050 ppm, respectively.

Acetamides↗

Gas chromatographic-mass spectrometric method for the analysis of dimethomorph fungicide in dried hops.

An analytical method for the determination of dimethomorph [(E,Z)-4-[3-(4-chlorophenyl)-3-(3,4-dimethoxyphenyl)acryloyl]morpholine] residues in dried hops was developed utilizing liquid-liquid partitioning, automated gel permeation chromatography (GPC), Florisil and aminopropyl solid phase extraction (SPE) column cleanups, and gas chromatography (GC) with mass selective detection (MSD). Method validation recoveries from dried hops ranged from 79 to 103% over four levels of fortification (0.1, 1.0, 5.0, and 20 ppm). Control and dimethomorph-treated hop samples collected from three field sites had residue levels of <0.10 and 4.06-17.32 ppm, respectively. The method was validated to the limit of quantitation at 0.10 ppm. The limit of detection for this method was 0.045 ppm.

Fungicides, Industrial↗

Orthophenylphenol and phenylhydroquinone residues in citrus fruit and processed citrus products after postharvest fungicidal treatments with sodium orthophenylphenate in California and Florida.

Sodium orthophenylphenate (SOPP) has been used extensively for >40 years to control postharvest diseases of citrus fruits. Studies of the metabolism of [(14)C]SOPP have identified orthophenylphenol (OPP) as the major metabolite with phenylhydroquinone (PHQ) as a minor metabolite. The whole-fruit tolerance in the United States for OPP is 10 ppm. This study was conducted to quantify terminal OPP and PHQ residues in whole Navel oranges, grapefruit, and lemons following SOPP applications at maximum application rates and following commercial application and fruit storage practices. OPP and PHQ residues also were determined in products processed from treated Navel oranges. OPP residues in lemons, Navel oranges, and grapefruit treated with SOPP using foamer wash and shipping wax applications remained below the 10 ppm tolerance, and PHQ residues were all < or =0.439 ppm. PHQ residues in whole fruit increased with time in commercial storage. OPP residues in all Navel orange matrices except oil remained relatively stable with time in commercial storage; residues in oil declined substantially while in storage.

Biphenyl Compounds↗

Thiabendazole uptake and storage performance of cactus pear [Opuntia ficus-indica (L.) Mill. Cv Gialla] fruit following postharvest treatments with reduced doses of fungicide at 52 degrees C.

The storage response of cactus pears [Opuntia ficus-indica Miller (L.) cv. Gialla] was investigated over 6 weeks at 6 degrees C, plus an additional week of simulated marketing period (SMP) at 20 degrees C, after a 3-min dip treatment with thiabendazole (TBZ) at 1000 mg/L at 20 degrees C or 150 mg/L TBZ at 52 degrees C. Untreated fruits were used as control. Following TBZ treatments at 20 and 52 degrees C, total residues were recovered from the peel of cactus pear, as the concentration of residues in the pulp was negligible. Treatments with 1000 mg/L TBZ at 20 degrees C resulted in a 2.82 mg/kg residue uptake (active ingredient, whole-fruit basis), whereas treatment at 150 mg/L TBZ left 1.09 mg/kg. TBZ showed great persistence over both storage and SMP: on average, in the fruits treated at 20 and 52 degrees C, over 72 and 68%, respectively, of TBZ was still present after SMP. Postharvest treatments with 1000 mg/L TBZ at room temperature did not affect the expression of slight-to-moderate chilling injury (CI), but reduced severe CI by approximately 50% and decay development by 63.4% in comparison to those of untreated fruit after SMP. The effectiveness of TBZ was much higher with the treatment at 150 mg/L TBZ at 52 degrees C, providing 91% control of severe CI and approximately 89% suppression of decay; no treatment damage occurred during storage and SMP. External appearance was better in fruit treated with 150 mg/L TBZ at 52 degrees C. Respiration rate, titratable acidity, soluble solids concentration, and acetaldehyde in the flesh were not significantly influenced by treatments. Ethylene production rate and ethanol levels in the flesh were significantly higher in the TBZ-treated fruit as opposed to those in the untreated control fruit.

Cold Temperature↗

Development of new fungicides against Magnaporthe grisea: synthesis and biological activity of pyrazolo[3,4-d][1,3]thiazine, pyrazolo[1,5-c][1,3,5]thiadiazine, and pyrazolo[3,4-d]pyrimidine derivatives.

Some pyrazolo[3,4-d]pyrimidin-4(5H)-thione, pyrazolo[3,4-d][1,3]thiazin-4-one/thione, and pyrazolo[1,5-c][1,3,5]thiadiazine-4-one/thione derivatives were synthesized and screened for antifungal activity against the causal agent of rice blast disease, Magnaporthe grisea. In all cases a remarkable inhibition of fungal growth was found in the range from 10 to 200 microg x mL(-1). Several compounds were able to control mycelium growth at a rate of 10 microg x mL(-1), a concentration at which the reference compound tricyclazole was completely ineffective. At least in the case of the most active substance, at the same dose the growth of seedlings or cultured cells of rice was substantially unaffected. Results allowed definition of structural requirements either to maintain or to enhance mycotoxic activity.

Fungicides, Industrial↗

Natural fungicides from Ruta graveolens L. leaves, including a new quinolone alkaloid.

Bioassay-directed isolation of antifungal compounds from an ethyl acetate extract of Ruta graveolens leaves yielded two furanocoumarins, one quinoline alkaloid, and four quinolone alkaloids, including a novel compound, 1-methyl-2-[6'-(3' ',4' '-methylenedioxyphenyl)hexyl]-4-quinolone. The (1)H and (13)C NMR assignments of the new compound are reported. Antifungal activities of the isolated compounds, together with 7-hydroxycoumarin, 4-hydroxycoumarin, and 7-methoxycoumarin, which are known to occur in Rutaceae species, were evaluated by bioautography and microbioassay. Four of the alkaloids had moderate activity against Colletotrichum species, including a benomyl-resistant C. acutatum. These compounds and the furanocoumarins 5- and 8-methoxypsoralen had moderate activity against Fusarium oxysporum. The novel quinolone alkaloid was highly active against Botrytis cinerea. Phomopsis species were much more sensitive to most of the compounds, with P. viticola being highly sensitive to all of the compounds.

Alkaloids↗

Determination of the fungicide validamycin A by capillary zone electrophoresis with indirect UV detection.

Validamycin A, a main component of the antibiotic validamycin complex, which is widely used to control sheath blight disease of rice plants, can be determined by capillary zone electrophoresis with indirect UV detection. The influence of various separation conditions including background electrolyte and modifier concentration, pH, and voltage was investigated. By using 10 mM aminopyrine-2 mM ethylenediaminetetraacetic acid at pH 5.2 as the carrier electrolyte, high efficiency separation of validamycin A was achieved with the number of theoretical plates up to 350000 plates/m. The linear range was across 3 orders of magnitude. The relative standard deviations for migration times and peak areas were less than 0.5 and 3.0%, respectively. The limit of detection for validamycin A was 1.0 microg/mL. The average recoveries ranged from 103.0 to 104.8%. This method has many advantages as compared with high-performance liquid chromatography and micellar electrokinetic capillary chromatography in the determination of commercial formulations.

Chromatography, High Pressure Liquid↗

Metabolism of fungicide diethofencarb in grape (Vitis vinifera L.): definitive identification of thiolactic acid conjugated metabolites.

The metabolic fate of diethofencarb (isopropyl 3,4-diethoxycarbanilate) separately labeled with (14)C at the phenyl ring and 2-position of the isopropyl moiety was studied in grape (Vitis vinifera L.). The acetonitrile solution of (14)C-diethofencarb at a rate of 500 g a.i. ha(-)(1) was once applied topically to fruits or leaves at the maturity stage of fruits (PHI 35 days), and the plants were grown in the greenhouse until harvest. In the grape plants, diethofencarb was scarcely translocated to the untreated portion and was degraded more in the fruit as compared to the leaf. For the fruit, diethofencarb primary underwent O-deethylation at the 4-position of the phenyl ring to form the phenolic derivative, isopropyl 3-ethoxy-4-hydroxycarbanilate (0.9% of the total radioactive residue, TRR). This metabolite was successively transformed via conjugation with glucose at the phenolic hydroxy group (8.1-18.1% TRR) or with thiolactic acid at the 5-position of the phenyl ring (1.5-1.7% TRR). The thiolactic acid conjugate was further metabolized mainly to two different types of glucose conjugates at the 4-position of the phenyl ring (8.7-13.5% TRR) and the hydroxy group in the thiolactic acid moiety (6.4-7.3% TRR), as evidenced by (1)H NMR and atmospheric pressure chemical ionization-liquid chromatography-mass spectrometry together with cochromatographies with synthetic standards.

Carbamates↗