Metabolism of a fungicide propiconazole by Cunninghamella elegans ATCC36112

The metabolic breakdown of propiconazole by fungi was examined, and it was found that the microbial model (Cunninghamella elegans ATCC36112) efficiently degrades the triazole fungicide propiconazole through the action of cytochrome P450. This enzyme primarily facilitates the oxidation and hydrolysis processes involved in phase I metabolism. We observed major metabolites indicating hydroxylation/oxidation of propyl groups of propiconazole. Around 98% of propiconazole underwent degradation within a span of 3 days post-treatment, leading to the accumulation of five metabolites (M1-M5). The experiments started with a preliminary identification of propiconazole and its metabolites using GC-MS. The identified metabolites were then separated and identified by in-depth analysis using preparative UHPLC and MS/MS. The metabolites of propiconazole are M1 (CGA-118245), M2(CGA-118244), M3(CGA-136735), M4(GB-XLIII-42-1), and M5(SYN-542636). To further investigate the role of key enzymes in potential fungi, we treated the culture medium with piperonyl butoxide (PB) and methimazole (MZ), and then examined the kinetic responses of propiconazole and its metabolites. The results indicated a significant reduction in the metabolism rate of propiconazole in the medium treated with PB, while methimazole showed weaker inhibitory effects on the metabolism of propiconazole in the fungus C. elegans.

Myclobutanil-mediated alteration of liver-gut FXR signaling in mice

The effects of exposure to Myclobutanil, a triazole fungicide, on the development and progression of nonalcoholic fatty liver disease (NAFLD) are unclear, but activation of nuclear receptors (NRs) is a known mechanism of azole-induced liver toxicity. Farnesoid X receptor (FXR) is a NR and is highly expressed in the liver and intestine. Activation of FXR tightly regulates bile acid (BA), lipid and glucose homeostasis, and inflammation partly through the induction of fibroblast growth factor 15 (FGF15; human ortholog FGF19). FXR activation is downregulated during NAFLD and agonists are currently being explored as potential therapeutic strategy. In this study, we aimed to clarify the effects of Myclobutanil exposure on FXR activation and NAFLD development. Reporter assay showed Myclobutanil treatment, following FXR activation with potent FXR agonist (GW4064), resulted in a dose-dependent decrease of FXR activity. Furthermore, a 10-day study in male mice demonstrated that cotreatment with Myclobutanil led to an 80% reduction of GW4064-induced ileal expression of Fgf15. In a diet-induced NAFLD study, low-fat diet (LFD) fed mice administered myclobutanil displayed decreased FXR activity in the liver and ileum, while high-fat-high-sugar-diet (HFHSD) fed mice showed an increase in hepatic FXR activity and an induction of target genes regulated by constitutive androstane receptor and/or pregnane X receptor. Our work demonstrates Myclobutanil inhibits FXR activity and modulates FXR activity differentially in mice fed LFD or HFHSD. Our studies suggest the importance of understanding how Myclobutanil could contribute to BA dysregulation in disease states such as NAFLD.

What can the Allium cepa test say about pesticide safety? A review

The increasing use of pesticides has caused global concerns about the toxic effects and adverse consequences of pesticides on humans and the environment. Among the ways to understand the impact of pesticides, the Allium cepa bioassay stands out. This test is suitable to evaluate different toxic, cytotoxic, genotoxic, and mutagenic outcomes. In this context, the present review aimed to summarize the history of using the A. cepa bioassay to investigate pesticide damages. Data on the experimental conditions were also discussed. The reviewed studies showed the toxicity profile of 113 active ingredients primarily tested in the laboratory, using water for exposure. The most used biomarkers were the mitotic index, chromosomal aberrations, and nuclear abnormalities. All active ingredients caused some toxicity levels in A. cepa, showing the efficiency and sensibility of this bioindicator and the adverse effect of pesticides on humans and the environment. Furthermore, it was evident that pesticides have great potential to damage the mitotic spindle and DNA because almost all active ingredients tested induced chromosomal aberrations and nuclear abnormalities. The current review showed that the A. cepa bioassay is an effective and appropriate model to evaluate pesticide toxicity, and it might indicate research gaps and recommendations for further studies.

Triazole Fungicide Residues and Their Inhibitory Effect on Some Trichothecenes Mycotoxin Excretion in Wheat Grains

Wheat is one of the global strategic crops and ranks third in terms of cereals production. Wheat crops are exposed to many fungal infections during their cultivation stages, some of which have the ability to secrete a number of toxic secondary metabolites that threaten the quality of the grains, consumer health, producer economics, and global trade exchange. Fifty-four random samples were collected from wheat which originated from different countries. The samples included 14 types of soft wheat to study the extent of their contamination with deoxynivalenol (DON) and T-2 toxin by auto-ELISA technology and r-biopharm microtiter plate. All samples were contaminated with DON toxin except one sample, and the values ranged between 40.7 and 1018.8 µg/kg⁻¹. The highest contamination rates were in Lithuanian wheat and the lowest was in Indian wheat. Meanwhile, the highest average level of T-2 toxin contamination was in Lithuanian wheat grains with 377.4 µg/kg⁻¹, and the lowest average was 115.3 µg/kg⁻¹ in Polish wheat. GC-MS/MS and multiple reaction monitoring mode (MRM) were used to detect 15 triazole derivatives in the collected samples, which may be used to combat fungal diseases on wheat during the growing season. Only 9 derivatives were found: simeconazole, penconazole, hexaconazole, cyproconazole, diniconazole, tebuconazole, metconazole, fenbuconazole, and difenoconazole. These derivatives varied according to the origin of the wheat samples as well as their concentration, whereas another 6 derivatives were not detected in any samples. A direct inverse relationship was found between the DON concentration in the samples and the residues of simeconazole, penconazole, diniconazole, tebuconazole, metconazole, fenbuconazole, and difenoconazole, and the T-2 toxin showed the same relationship except for tebuconazole. The safe and rational use of some triazole derivatives may be a new approach and a promising strategy to not only reduce plant diseases and their problems, but also to get rid of some mycotoxins as grain contaminants.

Aspergillosis, Avian Species and the One Health Perspective: The Possible Importance of Birds in Azole Resistance

The One Health context considers health based on three pillars: humans, animals, and environment. This approach is a strong ally in the surveillance of infectious diseases and in the development of prevention strategies. Aspergillus spp. are fungi that fit substantially in this context, in view of their ubiquity, as well as their importance as plant pathogens, and potentially fatal pathogens for, particularly, humans and avian species. In addition, the emergence of azole resistance, mainly in Aspergillus fumigatus sensu stricto, and the proven role of fungicides widely used on crops, reinforces the need for a multidisciplinary approach to this problem. Avian species are involved in short and long distance travel between different types of landscapes, such as agricultural fields, natural environments and urban environments. Thus, birds can play an important role in the dispersion of Aspergillus, and of special concern, azole-resistant strains. In addition, some bird species are particularly susceptible to aspergillosis. Therefore, avian aspergillosis could be considered as an environmental health indicator. In this review, aspergillosis in humans and birds will be discussed, with focus on the presence of Aspergillus in the environment. We will relate these issues with the emergence of azole resistance on Aspergillus. These topics will be therefore considered and reviewed from the “One Health” perspective.

The dissipation and microbial ecotoxicity of tebuconazole and its transformation products in soil under standard laboratory and simulated winter conditions

Tebuconazole (TBZ) is a widely used triazole fungicide at EU level on cereals and vines. It is relatively persistent in soil where it is transformed to various transformation products (TPs) which might be environmentally relevant. We assessed the dissipation of TBZ in soil under contrasting incubation conditions (standard vs winter simulated) that are relevant to its application scheme, determined its transformation pathway using advanced analytical tools and ¹⁴C-labeled TBZ and assessed its soil microbial toxicity. Mineralization of ¹⁴C-triazole-ring-labeled TBZ was negligible but up to 11% of ¹⁴C-penyl-ring-labeled TBZ evolved as ¹⁴CO₂ within 150 days of incubation. TBZ persistence increased at higher dose rates (×10 compared to the recommended agronomical dose ×1) and under winter simulated conditions compared to standard incubation conditions (at ×1 dose rate DT₅₀ of 202 and 88 days, respectively). Non-target suspect screening enabled the detection of 22 TPs of TBZ, among which 17 were unknown. Mass spectrometry analysis led to the identification of 1-(4-chlorophenyl) ethanone, a novel TP of TBZ, the formation of which and decay in soil was determined by gas chromatography mass spectrometry. Three hypothetical transformation pathways of TBZ, all converging to 1H-1,2,4-triazole are proposed based on suspect screening. The ecotoxicological effect of TBZ and of its TPs was assessed by measuring by qPCR the abundance of the total bacteria and the relative abundance of 11 prokaryotic taxa and 4 functional groups. A transient impact of TBZ on the relative abundance of all prokaryotic taxa (except α-proteobacteria and Bacteroidetes) and one functional microbial group (pcaH-carrying microorganisms) was observed. However the direction of the effect (positive or negative) varied, and in certain cases, depended on the incubation conditions. Proteobacteria was the most responsive phylum to TBZ with recovery observed 20 days after treatment. The ecotoxicological effects on the soil microorganisms were not correlated with 1-(4-chlorophenyl) ethanone.

Determination of Diniconazole in Agricultural Products, Livestock and Marine Products by LC-MS/MS

An LC-MS/MS method for the determination of diniconazole in agricultural products, livestock and marine products was developed. Diniconazole in agricultural products was extracted with acetone. The extract was concentrated and partitioned with n-hexane and 10% sodium chloride solution. Agricultural products such as grains and beans were defatted using n-hexane-acetonitrile. Livestock and marine products were extracted with a mixture of acetone and n-hexane, and the organic layer was evaporated to dryness. The residue was defatted using n-hexane-acetonitrile. Cleanup was carried out using a Florisil cartridge column and a graphitized carbon cartridge column for these samples. The LC separation was carried out on an Inertsil ODS-3 column with a linear gradient of 0.1% formic acid and acetonitrile containing 0.1% formic acid. MS was carried out in the positive ion electrospray ionization mode. The calibration curve was linear between 0.00125 to 0.00750 mg/L. Average recoveries (n=5) of diniconazole from 16 kinds of agricultural products, livestock and marine products fortified at the MRLs (0.01 ppm) were 88.3-108%, and the relative standard deviations were 0.5-5.1%. The limits of quantitation were 0.01 mg/kg.

Residues of the fungicide epoxiconazole in rice and paddy in the Chinese field ecosystem

BACKGROUND

Epoxiconazole is extensively used as fungicide in cereals, grapes and other crops worldwide. Rice is one of the world's most important food crops. Many people who depend on rice for their food live in Asia. A method employing liquid chromatography-tandem mass spectrometry was developed for determination of epoxiconazole in brown rice, straw, rice hull, paddy water and soils. Epoxiconazole residues in rice hull, brown rice, straw and soil were also determined.

RESULTS

The limit of quantitation was set at 0.01 mg kg(-1) for the matrices studied. Epoxiconazole degradation in straw, paddy water and soil was studied. The epoxiconazole residues in brown rice, straw, hull and paddy soil were determined. Concurrent recoveries were between 89.2 and 104.1%, with relative standard deviations ranging from 4.6 to 14.4% at three fortification levels between 0.01 and 5.0 mg kg(-1). The half-lives in straw, paddy water and soils were found to be 4.7-5.9, 2.9-6.0 and 2.9-6.4 days respectively. The maximum residues in brown rice, straw, hull and paddy soil samples were 0.18, 2.47, 2.54 and 0.09 mg kg(-1) respectively.

CONCLUSION

Compared with the maximum residue levels (MRLs) for epoxiconazole in rice that have been set by the European Union (0.1 mg kg(-1)) and by China (0.5 mg kg(-1)), the epoxiconazole residue on rice at an application rate of 112.5 g AI ha(-1) with two applications at an interval of 7 days, and with a 28 day preharvest interval (PHI), is below the MRL, and thus the use of epoxiconazole is considered to be safe. Epoxiconazole should be applied correctly, according to good agricultural practice, using only the recommended amounts, frequencies and appropriate PHI.

Stereoselective dissipation of epoxiconazole in grape (Vitis vinifera cv. Kyoho) and soil under field conditions

Stereoselective dissipation of epoxiconazole had been studied in grape and soil during plant growing under field conditions in this paper. A sensitive and rapid chiral method was developed and validated for the determination of epoxiconazole stereoisomers in grape and soil based on liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS). Phenomenex Lux Cellulose-1 column was used for enantioseparation with a mixture of acetonitrile/water (90/10, v/v) as mobile phase at flow rate of 0.3 mL min(-1). Fortified recoveries in grape and soil samples ranged from 76.0% to 91.9% and relative standard deviations were less than 11.4% with fortified levels of 0.025-1.0 mg kg(-1). The limits of detection and quantification were 0.005 mg kg(-1) and 0.025 mg kg(-1), respectively, with linear calibration curves extending up to 5.0 mg kg(-1). The field experimental results showed that dissipations of epoxiconazole stereoisomers in grape followed first-order kinetics (R(2)>0.92) and stereoselectivity occurred in 2 h after spraying. The (-)-stereoisomer with half-life of 9.3 d degraded faster than (+)-stereoisomer with that of 13.2 d, and resulted in relative enrichment of (+)-stereoisomer. However, the stereoisomeric dissipations in soil were triphasic ("increase-decrease-steady") with lower dissipation rates, and also occurred with preferential degradation of (-)-stereoisomer under field condition. The results for stereoselective dissipations can be applied for food and environmental assessments of chiral pesticides.

Enantioselective analysis of triazole fungicide myclobutanil in cucumber and soil under different application modes by chiral liquid chromatography/tandem mass spectrometry

A sensitive and enantioselective method was developed and validated for the determination of myclobutanil enantiomers by chiral liquid chromatography coupled with tandem mass spectrometry. The separation and determination were performed using reversed-phase chromatography on a Chiralcel OD-RH column, with ACN-water (70/30, v/v) as the mobile phase under isocratic conditions at 0.5 mL/min flow rate. The matrix effect, linearity, precision, accuracy, and stability were evaluated. The proposed method then was successfully applied to the study of enantioselective degradation of rac-myclobutanil in cucumber and soil under different application modes. The results showed that the preferential degradation of (+)-myclobutanil resulted in an enrichment of the (-)-myclobutanil residue in plant and soil. Moreover, in cucumber, the stereoselective intensity of myclobutanil under root douche treatment was stronger than that under foliar spraying treatment, whereas in soil, the intensity was exactly opposite. The probable reasons underlying these enantioselective effects were also discussed. This study highlighted the importance of examining the fate of both enantiomers in the greenhouse system for the correct use of chiral pesticides.

Persistence of trifloxystrobin and tebuconazole on grape leaves, grape berries and soil

Following four foliar applications of Nativo 75 WG (trifloxystrobin 25% + tebuconazole 50%) on grapes @ 175 and 350 g/ha, resulting in active applications of trifloxystrobin @ 43.75 and 87.5 g a.i./ha and that of tebuconazole @ 87.5 and 175 g a.i./ha, the average initial deposits of trifloxystrobin were observed to be 7.76 and 15.53 mg/kg, respectively, at single and double the application rates. These residue levels dissipated to >85% after 10 days of its application at both the dosages. Similarly, the average initial deposits of tebuconazole were observed to be 13.84 and 26.55 mg/kg at single and double the application rate, respectively. These residue levels dissipated to >90% after 10 days of application at both the dosages. The half-life (t(1/2)) periods of trifloxystrobin on grape leaves were observed to be 2.92 and 3.48 days at single and double application rates, respectively, whereas these values were 2.68 and 3.96 days for tebuconazole. Ripe grape berries and soil samples collected at harvest which happened to be 34 days after the last application, did not show the presence of residues of trifloxystrobin and tebuconazole at their determination limit of 0.01 and 0.02 mg/kg, respectively.

Contribution of leaf growth on the disappearance of fungicides used on tea under South Indian agroclimatic conditions

The sprayed chemicals on tea leaves disappear over a period of time by the influence of rainfall elution, evaporation, growth dilution, and photodegradation. Influence of plant growth on the four fungicides (hexaconazole, propiconazole, tridemorph, and c) was studied to know the constructive loss of fungicides. The study shows that residues of fungicides sprayed on tea shoots got diluted by the growing process. The expansion of a leaf took 8 to 11 d and more than 50% of the fungicide residues were cleaned out during this leaf expansion period. Under south Indian agroclimatic condition, the fungicides are sprayed at an interval of 10 d, so it is safe that the tea is harvested on the 10th day of the application of fungicides.

Optimisation of pressurised liquid extraction by experimental design for quantification of pesticides and alkyl phenols in sludge, suspended materials and atmospheric fallout by liquid chromatography-tandem mass spectrometry

The study proposes an analytical method to quantify 10 alkylphenols and 12 pesticides at ultra-trace levels by liquid chromatography in reverse mode coupled to positive electrospray ionisation-tandem mass spectrometry. The extraction procedure from environmental solids was optimised by pressurised liquid extraction using acetonitrile:isopropanol (1:1, v/v). The influence of several extraction experimental factors, temperature, pressure, duration and number of cycles, related to the PLE was investigated by an original and efficient chemometric approach. The optimised extraction method (80 degrees C, 40 bar, 10 min, 1 cycle) exhibited recoveries between 67 and 127% with RSD mostly under 13%. The whole method was applied to real samples: sludge, suspended materials, atmospheric fallouts and roof deposit. Pollutant levels were between 1 microg kg(-1) and 5.9 mg kg(-1).

Assessment of fungicide systemicity in wheat using LC-MS/MS

BACKGROUND

Systemicity is an important attribute of fungicides that is difficult to measure in early-stage screening without labeling the compound with a radioisotope. A method of measuring translocation that does not require potent fungicidal activity or a radiolabel would guide identification of compounds with desirable attributes.

RESULTS

The authors developed an analytical technique that mimics field application, using LC-MS/MS to screen compounds for translocation in wheat leaves. The method sorted commercial and experimental fungicides appropriately into systemic and non-systemic categories. A model using LC-MS/MS data was equivalent to a lipophilicity model and superior to a water solubility model at predicting compound systemicity.

CONCLUSION

Early-stage compounds can be screened for systemicity on whole plants using LC-MS/MS.

Development of monoclonal immunoassays for the determination of triazole fungicides in fruit juices

Enzyme-linked immunosorbent assays (ELISAs) based on monoclonal antibodies for the detection of triazole fungicides have been developed. With this aim, hapten-protein conjugates, containing the common triazole and chlorinated aromatic moieties, were prepared. From mice immunized with these conjugates, several monoclonal antibodies (MAbs) with the ability to sensitively bind several triazoles with different specificity were obtained. Both analyte- and class-specific ELISAs were developed. The hexaconazole-specific immunoassay can determine this fungicide with a limit of detection of 0.3 mug/L in standard buffer. The so-called triazole-specific immunoassay allowed for the detection of tetraconazole, penconazole, cyproconazole, and myclobutanil, with limits of detection in the 0.1-0.7 mug/L range. These immunoassays were applied to the determination of triazoles in spiked fruit juices. Samples were adequately diluted to minimize the matrix effects. Coefficients of variation were below 30%, and recoveries ranged from 62 to 135%. Therefore, the developed immunoassays can determine triazole fungicides in fruit juices down to the maximum residue limits currently legislated, without any sample treatment other than dilution.

Gas chromatographic method for the determination of hexaconazole residues in black tea

A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed by gas chromatographic determination, using nitrogen phosphorus detector (GC-NPD) for the identification and quantitation of hexaconazole. The most appropriate solvent mixture for extracting hexaconazole residues from black tea was n-hexane:acetone at 1:1 (v/v). The extract was cleaned up by adsorption column chromatography using activated florisil. Performance of the method was assessed by evaluating quality parameters such as recovery value, repeatability, reproducibility, linearity and limits of detection and quantitation. When the method was assessed for repeatability, the percentage of recovery ranged between 86% and 96% while the relative standard deviation was between 0.30% and 2.35%. In studies on reproducibility the recovery ranged from 81% to 85% and relative standard deviation from 1.68% to 5.13%, implying that the method was reliable. A field trial was conducted to verify the application of this method with real samples. Results prove that the validated method was suitable for extracting hexaconazole residues.

Determination of Tetraconazole and Diniconazole Fungicide Residues in Tomatoes and Green Beans by Capillary Gas Chromatography

A sensitive gas chromatographic method using an electron-capture detector (ECD) has been developed for the determination of tetraconazole and diniconazole fungicide residues in tomatoes and green beans. The developed method consists of extraction with methanol, partition with methylene chloride, and column chromatographic clean-up, followed by capillary gas chromatographic determination. The recoveries of both fungicides were greater than 90% for both plant samples. The limits of determination of the method were 0.001 ppm for both fungicides. The method was applied to determine residues and the rate of disappearance of tetraconazole and diniconazole from tomatoes and green beans [open field treatment, 50 cc of Domark 10% EC (emulsifiable concentrate), and 35 cc of Sumi-eight 5% EC; both for 100 l of water]. The fungicides incorporated into the plants decreased rapidly with a half-life around 3 days for diniconazole and from 4.5 to 6.5 days for tetraconazole. No residues could be detected in the plants during the period of study of 21 days after field application. Hence, the plants could be used safely after that period of time.

Mass spectrometry for monitoring micropollutants in water

Surface water reservoirs and aquifers are exposed to contamination by thousands of micropollutants from industrial, pharmaceutical, agricultural and natural origins. Most developed and developing countries implement a water-quality regulation programme to prevent contamination by such chemicals at illegal concentrations. Traditionally, analytical methods based on gas chromatography-mass spectrometry or liquid chromatography with UV/fluorescence detection were used to monitor water quality. These methods require multistep sample preparation and several have low specificity. Nowadays, liquid chromatography tandem mass spectrometry has become a key technique for environmental analysis, allowing the detection of a wide range of polar and nonvolatile compounds. The use of this method has increased the specificity and confidence of identification, while reducing sample preparation to a minimum.

Determination of several pesticides in water by solid-phase extraction, liquid chromatography and electrospray tandem mass spectrometry

The analysis of pesticides in water samples is a problem of primary concern for quality control laboratories due to the toxicity level of these compounds and their public health risk. In order to evaluate the impact of pesticides in the Lisbon drinking water supply system, following the requirements of the European Union Directive 98/83/EC, we developed and validated an analytical method based on the combination of solid-phase extraction with liquid chromatography and tandem mass spectrometry. In this work, several pesticides were studied: imidacloprid, dimethoate, cymoxanil, carbendazime, phosmet, carbofuran, isoproturon, diuron, methidathion, linuron, pyrimethanil, methiocarbe, tebuconazole and chlorpyrifos. Several parameters of the electrospray source were optimized in order to get the best formation conditions of the precursor ion for each pesticide, namely capillary and extractor voltage, cone voltage, cone gas flow rate and desolvation gas flow rate. After optimization of the collision cell energy of the triple quadrupole, two different precursor ion-product ion transitions were selected for each pesticide, one for quantification and one for qualification, and these ions were monitored under time-scheduled multiple reaction monitoring (MRM) conditions. The selection of specific fragment ions for each pesticide guarantees a high degree of selectivity as well as additional sensitivity to quantify trace levels of these pesticides in water samples. This method showed excellent linearity ranges for all pesticides, with correlation coefficients greater than 0.9989. Determination limits (between 0.0041 and 0.0480 microg/L), precision (RSD <9.18%), accuracy and recovery studies in several water samples using solid-phase extraction were also performed.