Gender-related differences in stereoselective degradation of flutriafol in rabbits

Enantioselective metabolism of fenpropathrin enantiomers by carboxyl/choline esterase 6 in Tetranychus cinnabarinus

BACKGROUND

Tetranychus cinnabarinus is a polyphagous pest mite commonly found in agriculture. As an excellent acaricide, fenpropathrin (FEN) is frequently used to control T. cinnabarinus in agriculture. However, commercial FEN is a racemate with two enantiomers, R-FEN and S-FEN. Considering that investigations on the metabolism of FEN by T. cinnabarinus are based on racemate FEN, it is important to investigate the enantioselective metabolism of FEN in T. cinnabarinus.

RESULTS

S-FEN was more toxic to T. cinnabarinus than R-FEN by more than 68.8-fold. Moreover, the synergist bioassay revealed that carboxylesterase and cytochrome P450 were the primary enzymes engaged in the detoxification of FEN in T. cinnabarinus, with carboxylesterase playing a leading role. Seven genes were substantially different after the induction of S-FEN and R-FEN. TcCCE06 was screened and selected as a key gene that related to FEN metabolism in T. cinnabarinus. The metabolic results showed that the recombinant TcCCE06 effectively metabolized 32.1% of the R-FEN and 13.8% of the S-FEN within 4 h of incubation. Moreover, R-FEN was demonstrated to have a higher affinity for the TcCCE06 protein than S-FEN based on molecular docking.

CONCLUSION

Our results indicated that TcCCE06 mediates the enantioselective metabolism of FEN in T. cinnabarinus. Our findings will contribute to a more comprehensive understanding of the mechanisms underlying the differential toxicity of the FEN enantiomers against T. cinnabarinus. Furthermore, they also provide a new perspective for the development of enantiomer-enriched acaricides with higher activity and lower pesticide dosage and pollution risks. © 2023 Society of Chemical Industry.

Enantioselective Behaviors of Chiral Pesticides and Enantiomeric Signatures in Foods and the Environment

Unreasonable application of pesticides may result in residues in the environment and foods. Chiral pesticides consist of two or more enantiomers, which may exhibit different behaviors. This Review intends to provide progress on the enantioselective residues of chiral pesticides in foods. Among the main chiral analytical methods, high performance liquid chromatography (HPLC) is the most frequently utilized. Most chiral pesticides are utilized as racemates; however, due to enantioselective dissipation, bioaccumulation, biodegradation, and chiral conversion, enantiospecific residues have been found in the environment and foods. Some chiral pesticides exhibit strong enantioselectivity, highlighting the importance of evaluation on an enantiomeric level. However, the occurrence characteristics of chiral pesticides in foods and specific enzymes or transport proteins involved in enantioselectivity needs to be further investigated. This Review could help the production of some chiral pesticides to single-enantiomer formulations, thereby reducing pesticide consumption as well as increasing food production and finally reducing human health risks.

Enantioselective Effect of Flutriafol on Growth, Deoxynivalenol Production, and TRI Gene Transcript Levels in Fusarium graminearum

In recent years, deoxynivalenol (DON) has frequently been detected in wheat grains and their products. The enantioselective impact of flutriafol on the growth and DON biosynthesis of Fusarium graminearum was investigated in relation to water activity (α_w, 0.97 and 0.99) and temperature (20, 25, and 30 °C) on the wheat-based medium. R-(-)-flutriafol exhibited higher bioactivity than S-(+)-flutriafol and Rac-flutriafol under the above conditions. Flutriafol enantiomers reduced or stimulated DON biosynthesis depending on α_w. DON levels were negligible after 14 or 7 days of incubation times under 0.97 and 0.99 a_w, respectively. Quantitative real-time polymerase chain reaction (qRT-PCR) analyses showed that the expression levels of trichothecene biosynthetic (TRI) genes of F. graminearum under 0.97 a_w were significantly higher than those under 0.99 a_w. In addition, R-(-)-flutriafol can induce more TRI gene expression than S-(+)-flutriafol. Taken together, this study indicated that a_w and temperature play important roles in regulating DON biosynthesis in F. graminearum with flutriafol enantiomers.

Kidney developmental effects of metal-herbicide mixtures: Implications for chronic kidney disease of unknown etiology

Chronic kidney disease of unknown etiology (CKDu) is an emerging global concern affecting several agricultural communities in the Americas and South Asia. Environmental contaminants such as heavy metals (e.g., Cd, As, Pb, and V) and organic pesticides (e.g., glyphosate) in the drinking water have been hypothesized to play a role in childhood onset and progression of this disease. However, a comprehensive analysis of chemical contaminants in the drinking water and effects of these compounds and their mixtures on kidney development and function remains unknown. Here, we conducted targeted and non-targeted chemical analyses of sediment and drinking water in CKDu affected regions in Sri Lanka, one of the most affected countries. Using zebrafish Danio rerio, a toxicology and kidney disease model, we then examined kidney developmental effects of exposure to (i) environmentally derived samples from CKDu endemic and non-endemic regions and (ii) Cd, As, V, Pb, and glyphosate as individual compounds and in mixtures. We found that drinking water is contaminated with various organic chemicals including nephrotoxic compounds as well as heavy metals, but at levels considered safe for drinking. Histological studies and gene expression analyses examining markers of kidney development (pax2a) and kidney injury (kim1) showed novel metal and glyphosate-metal mixture specific effects on kidney development. Mitochondrial dysfunction is directly linked to kidney failure, and examination of mixture specific mitochondrial toxicity showed altered mitochondrial function following treatment with environmental samples from endemic regions. Collectively, we show that metals in drinking water, even at safe levels, can impede kidney development at an early age, potentiating increased susceptibility to other agrochemicals such as glyphosate. Drinking water contaminant effects on mitochondria can further contribute to progression of kidney dysfunction and our mitochondrial assay may help identify regions at risk of CKDu.

Multi-level analysis of exposure to triazole fungicides through treated seed ingestion in the red-legged partridge

Triazole fungicides are the most widely used products to treat cereal seeds. Granivorous birds, such as red-legged partridges (Alectoris rufa), which consume seeds left on the surface of fields after sowing, have a high risk of exposure. As triazole fungicides can affect sterol synthesis, we tested the hypothesis that treated seed consumption could alter the synthesis of sex hormones and reduce the reproductive capacity of partridges. We exposed adult partridges to seeds treated with four different formulations containing triazoles as active ingredients (flutriafol, prothioconazole, tebuconazole, and a mixture of the latter two) simulating a field exposure during the late autumn sowing season. All treatments produced biochemical changes and an overexpression of genes encoding for enzymes involved in the biosynthesis of sterols and steroid hormones, such as PMVK, ABCA1, MVD, PSCK9, DHCR7 and HSD17B7. Plasma levels of oestradiol were reduced in partridges exposed to tebuconazole. We also monitored reproduction 3 months after exposure (laying date, egg fertilization and hatching rates). We observed a 14-day delay in the laying onset of partridges that had been exposed to flutriafol as compared to controls. These results show that the consumption of seeds treated with triazole fungicides has the potential to affect granivorous bird reproduction. We recommend the evaluation of lagged reproductive effects as part of the protocols of environmental risk assessment of pesticides in wild birds in light of the effects resulting from the exposure to triazole-treated seeds.

Electrochemical treatment of flutriafol wastewater using a novel 3D macroporous PbO2 filter: Operating parameters, mechanism and toxicity assessment

In order to break the high operating cost bottleneck of electrochemical treatment of aqueous flutriafol (FTF), an emerging fungicide, a novel three-dimensional ordered macroporous PbO₂ (3DOM-PbO₂) filter was designed to facilitate mass transfer. The effects of operating parameters, including current density, flow rate and initial concentration on FTF electrooxidation performance were investigated using conventional flat Ti/PbO₂ (F-Ti/PbO₂) and 3DOM-PbO₂ filters, with primary objective being the development of appropriate parameters for FTF treatment. The results indicated that the FTF removal efficiency on 3DOM-PbO₂ filter was improved by 2.8 times compared to that on F-Ti/PbO₂ at 5 mA cm^-2, 10 ml s^-1 and 100 mg L^-1 FTF. The corresponding electrical energy consumption was reduced by 2.7 times, ` TOC removal and mineralization current efficiency were enhanced by 4.9 and 4.8 times, respectively. Furthermore, aromatic intermediates, nitrogenous compounds and carboxylic acids were identified as main byproducts using experimental method combined with quantum chemical calculations. Then, a possible pathway of FTF degradation on 3DOM-PbO₂ was proposed. Finally, the acute toxicity results showed that toxicity of the byproducts first increases and then decreases through the proposed route. LC_50,48 h value of FTF wastewater increased 35%-70% on the 3DOM-PbO₂ filter, indicating a significant biodegradability enhancement.

Mechanistic Insights into Stereospecific Bioactivity and Dissipation of Chiral Fungicide Triticonazole in Agricultural Management

Research interest in chiral pesticides has increased probably because enantiomers often exhibit different environmental fate and toxicity. An investigation into the enantiomer-specific bioactivity of chiral triticonazole enantiomers in agricultural systems revealed intriguing experimental and theoretical evidence. For nine of the phytopathogens studied ( Rhizoctonia solani, Fusarium verticillioide, Botrytis cinerea (strawberry and tomato), Rhizoctonia cereali, Alternaria solani, Gibberella zeae, Sclerotinia sclerotiorum, and Pyricularia grisea), the fungicidal activity data showed ( R)-triticonazole was 3.11-82.89 times more potent than the ( S) enantiomer. Furthermore, ( R)-triticonazole inhibited ergosterol biosynthesis and cell membrane synthesis 1.80-7.34 times higher than its antipode. Homology modeling and molecular docking studies suggested the distinct bioactivities of the enantiomers of triticonazole were probably due to their different binding modes and affinities to CYP51b. However, field studies demonstrated that ( S)-triticonazole was more persistent than ( R)-triticonazole in fruits and vegetables. The results showed that application of pure ( R)-triticonazole, with its high bioactivity and relatively low resistance risk, instead of the racemate in agricultural management would reduce the application dosage required to eliminate carcinogenic mycotoxins and any environmental risks associated with this fungicide, yielding benefits in food safety and environmental protection.

The fate of technical-grade chlordane in mice fed a high-fat diet and its roles as a candidate obesogen

Epidemiological studies indicate that exposure to persistent organic pollutants is positively associated with the prevalence of obesity. To delineate the potential role of technical-grade chlordane in obesity development, chlordane metabolism and chlordane-induced metabolic changes were investigated in mice fed high-fat diet (HFD) over a 6-week period. Gas chromatography-electron capture detector analysis showed that HFD induced more accumulation of technical chlordane in the liver, muscle and adipose tissue. The enantioselectivities of oxychlordane in selected tissues were also influenced by HFD. ¹H NMR-based liver metabolome indicated that technical chlordane can enhance the metabolic alterations induced by HFD. Compared with the low-fat diet (LFD) group, no differences were observed in the LFD + chlordane group. However, as many as 16 metabolites were significantly different between the HFD group and HFD + chlordane group. Moreover, compared to the LFD + chlordane group, the abundances of 24 metabolites significantly increased or decreased in the HFD + chlordane group. Twenty metabolites were altered in the HFD group compared to the LFD group. Tryptophan profiling suggested that both chlordane and HFD can disturb tryptophan catabolism. These interactions between technical chlordane and HFD suggest that technical chlordane is a candidate obesogen.

Enantioselective bioactivity, acute toxicity and dissipation in vegetables of the chiral triazole fungicide flutriafol

The enantioselective bioactivity, acute toxicity and stereoselective degradation of the chiral triazole fungicide flutriafol in vegetables were investigated for the first time using the (R)-, (S)- and rac-flutriafol. The order of the bioactivity against five target pathogens (Rhizoctonia solani, Alternaria solani, Pyricularia grisea, Gibberella zeae, Botrytis cinerea) was found to be (R)-flutriafol>rac-flutriafol>(S)-flutriafol. The fungicidal activity of (R)-flutriafol was 1.49-6.23 times higher than that of (S)-flutriafol. The (R)-flutriafol also showed 2.17-3.52 times higher acute toxicity to Eisenia fetida and Scenedesmus obliquus than (S)-flutriafol. The stereoselective degradation of flutriafol in tomato showed that the active (R)-flutriafol degraded faster, resulting in an enrichment of inactive (S)-form, and the half-lives were 9.23 d and 10.18 d, respectively. Inversely, the (S)-flutriafol, with a half-life of 4.76 d, was preferentially degraded in cucumber. In conclusion, the systemic assessments of the triazole fungicide flutriafol stereoisomers on the enantioselective bioactivity, acute toxicity and environmental behavior may have implications for better environmental and ecological risk assessment.

Stereoselective degradation of flutriafol and tebuconazole in grape

The stereoselective dissipation of flutriafol and tebuconazole in grape had been studied. A simple and sensitive method for determination of flutriafol and tebuconazole enantiomers in grape was developed by high-performance liquid chromatography on a cellulose tris(3-chloro-4-methylphenylcarbamate) column. The limits of quantification for flutriafol and tebuconazole in grape were 0.033 and 0.043 mg kg(-1), respectively. The dissipations of flutriafol and tebuconazole stereoisomers in grape followed first-order kinetics (R (2) > 0.93). The stereoisomers of flutriafol and tebuconazole were enantioselectively degraded in grape, and tebuconazole was more enantioselective than flutriafol. The half-life of (-)-tebuconazole was 5.2 days and shorter than (+)-tebuconazole with half-life of 6.4 days. The (-)-flutriafol was also preferentially degraded in grape, the half-lives of which were 6.59 and 6.98 days for (-) and (+)-flutriafol, respectively. The enantiomeric ratio value of the two fungicides was nearly 1.0 at the 1st day and increased to 1.143 for flutriafol and 2.015 for tebuconazole at the 28th day. The stereoselective dissipations could provide a reference to fully evaluate the risks of two important chiral triazole fungicides.

Green and sensitive supercritical fluid chromatographic-tandem mass spectrometric method for the separation and determination of flutriafol enantiomers in vegetables, fruits, and soil

A green and sensitive chiral analytical method was developed to determine flutriafol enantiomers in vegetables (tomato, cucumber), fruits (apple, grape), and soil by supercritical fluid chromatography-tandem mass spectrometry. The enantioseparation was performed within 3.50 min using Chiralpak IA-3 column with CO2/methanol (88:12, v/v) as the mobile phase at a 2.2 mL/min flow rate. The postcolumn compensation technology provided with 1% formic acid/methanol greatly improved the ionization efficiency of mass spectrometry. Column temperature, auto back pressure regulator pressure, and flow rate of compensation solvent were optimized to 30 °C, 2200 psi, and 0.1 mL/min, respectively. The simple and fast QuEChERS pretreatment method was adopted. Mean recoveries for flutriafol enantiomers were 77.2-98.9% with RSDs ≤ 9.6% in all matrices. The limits of quantification ranged from 0.41 to 1.18 μg/kg. Well-applied to analyze authentic samples, the developed method could act as a versatile strategy for the analysis of flutriafol enantiomers in food and environmental matrices.

Enantioselective analysis and dissipation of triazole fungicide penconazole in vegetables by liquid chromatography-tandem mass spectrometry

Penconazole is a typical triazole fungicide, which is commonly used to control powdery mildew in vineyard and vegetable field. In this study, the enantioselective dissipation of penconazole in cucumber, tomato, head cabbage, and pakchoi was investigated by field experiments. A sensitive method for enantiomeric analysis of penconazole was established on the basis of the buffered QuEChERS sample preparation technique followed by reverse-liquid chromatography equipped with a TSQ Discovery triple quadrupole mass spectrometer and a Lux Cellulose-2 chiral column. Methanol and 2 mM ammonium acetate buffer solution containing 0.1% formic acid (70:30, v/v) were used as mobile phase at a 0.2 mL L(-1) flow rate isocratic elution. The linearity, recovery, and precision of this method were also evaluated. Finally, the results of this study demonstrated that enantioselective dissipation occurred in head cabbage and pakchoi, with the preferential degradation of (-)-penconazole, and resulting in an enrichment of the (+)-penconazole residue in the two vegetables. However, the enantioselective behavior was not observed in cucumber and tomato. More importantly, this is the first report of enantioselective behavior of penconazole, and the result may provide useful information for the risk evaluation of penconazole in food and environmental safety.

Evaluating the enantioselective degradation and novel metabolites following a single oral dose of metalaxyl in mice

Metalaxyl [N-(2,6-dimethylphenyl)-N-(methoxyacetyl)-D,L-alaninemethylester] is a systemic fungicide widely used in agriculture. In this study, the enantioselective distribution, degradation and excretion of metalaxyl were investigated after oral gavage administration of rac-metalaxyl to mice. Concentration of metalaxyl and its enantiomers was determined by HPLC-MS/MS. The results showed that R-metalaxyl was much higher than S-metalaxyl in heart, liver, lung, urine and feces. As for the strong first pass effect, concentrations of metalaxyl in liver were much higher than those in other tissues. The total body clearance (CL) of metalaxyl in mice was 1.77 L h(-1 )kg(-1) and degradation half-lives of (t1/2) of S-metalaxyl and R-metalaxyl in liver were 2.2 h and 3.0 h, respectively. Such results indicated the enantioselectivity of metalaxyl lies in distribution, degradation and excretion processes in mice. Main metabolites were also determined and biotransformation reactions were hydroxylation, demethylation and didemethylation. Furthermore, metabolite concentrations in urine and feces were much higher than those in tissues. These results may have potential implications to predict toxicity and provide additional information associated with adverse health effects for risk assessment of metalaxyl.

Simultaneous enantioselective determination of triazole fungicide flutriafol in vegetables, fruits, wheat, soil, and water by reversed-phase high-performance liquid chromatography

A novel and effective method for enantioselective determination of flutriafol enantiomers in food and environmental matrices (cucumber, tomato, grape, pear, wheat, soil, and water) has been developed. The (R)-(-)-flutriafol was first eluted and measured from electronic circular dichroism spectra using a cellulose tris(3-chloro-4-methyl phenyl carbamate) chiral column. The mean recoveries from the samples ranged from 82.9% to 103.4%, with intraday relative standard deviations (RSD) of 2.2-8.3% and interday RSD of 3.4-7.9%. Good linearity (R(2) ≥ 0.9989) was obtained for all analytes matrix calibration curves within the range of 0.1-10 mg/kg. The limits of detection for two enantiomers in the seven matrices were all below 0.015 mg/kg. The results show that the proposed method is convenient and reliable for the enantioselective detection of the flutriafol in the real samples and is applicable to the environmental stereochemistry of flutriafol in food and environmental matrices.