Characterization of hepatotoxic effects induced by pyraclostrobin in human HepG2 cells and zebrafish larvae

Co-exposure of pyraclostrobin and biochar promoted antibiotic resistance genes transfer from soil to lettuce

The widespread presence of antibiotic resistance genes (ARGs) threatens ecological security and human health. In agricultural production, the simultaneous presence of non-antibiotic substances fungicides and biochar utilized for soil remediation has unclear effects on the spread of ARGs in the soil-vegetable systems. Herein, this study conducted a pots experiment and found that biochar significantly reduced pyraclostrobin accumulation in the soil and lettuce roots. Simultaneously, the co-exposure of pyraclostrobin and biochar increased the microbial community alpha diversity and the abundance of ARGs in soil, while promoting the transfer of ARGs from soil to lettuce. Proteobacteria were identified as potential primary carriers of ARGs. Planting lettuce mitigated the effects of pyraclostrobin or/and biochar on ARGs accumulation in soil. Furthermore, MGEs and bacterial community abundance were the most important direct factors increasing ARGs in soil and lettuce. Overall, these findings evaluated the combined effects of non-antibiotic substances fungicides and soil remediation materials biochar on the generation and transmission of ARGs, providing potential strategies for controlling ARGs transfer in soil-vegetable systems.

Pyraclostrobin-induced toxic effects in the gills of common carp (Cyprinus carpio L.): Mechanisms unveiled through biochemical, molecular, and metabolomic analyses

Pyraclostrobin (PYR) is widely used in agriculture to control fungal infestations. However, the toxic effects of PYR on aquatic organisms remain poorly understood. In this study, common carp were exposed to 0.5, and 5.0 μg/L PYR for 30 days to evaluate the chronic effects on gill health via histopathological, biochemical, molecular, and metabolomic analyses. The findings revealed that exposure to PYR resulted in significant histopathological alterations, suppression of mitochondrial complex III activity, and excessive production of reactive oxygen species (ROS), including O2•- and H2O2. Additionally, PYR exposure altered the levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) while increasing the malondialdehyde (MDA) content in the gills of common carp. The protein expression levels of lysozyme (LZM), tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), and transforming growth factor beta (TGF-β) were significantly elevated following exposure to PYR, whereas the levels of complement 3 (C3) and immunoglobulin M (IgM) were decreased. Furthermore, the amount of IL-6 decreased on day 15 before increasing on day 30. Further analysis revealed a notable increase in acid phosphatase (ACP) activity and a decrease in alkaline phosphatase (AKP) activity after 30 days of PYR exposure. Moreover, PYR exposure significantly altered the mRNA expression levels of immune-related genes (lzm, c3, and igm) and apoptosis-related genes (p53, bcl-2, bax, caspase-3, and caspase-9). Several inflammatory markers, such as NF-κB p65 protein and the mRNA levels of tlr2, tlr4, myd88, tnf-α, il-1β, il-6, and tgf-β, were also markedly changed. Metabolomic studies demonstrated that PYR influences pathways related to amino acid, nucleotide, arachidonic acid, and linoleic acid metabolism. These results indicate that PYR adversely affects gill health by inducing oxidative stress, disrupting immune and inflammatory responses, affecting apoptosis-related pathways, and altering metabolic homeostasis. This study provides new insights into the toxic mechanisms of PYR and contributes to the assessment of the ecological risks associated with its presence in aquatic ecosystems.

Mitochondrial dysfunction induced in human hepatic HepG2 cells exposed to the fungicide kresoxim-methyl and to a mixture kresoxim-methyl/boscalid

The fungicides strobilurins and succinate dehydrogenase inhibitors (SDHIs) are blockers of the electron transport chain (ETC) in fungi. Here, we show that the exposure for 24 h to kresoxym-methyl, a fungicide from the class of strobilurins, alters the mitochondrial respiration in human HepG2 hepatocytes. In addition, we demonstrate an increase in production of mitochondrial superoxide radical anion, a reduction in ATP level, a decrease in the ratio reduced/oxidized glutathione and a decrease in cell viability (assessed by the LDH assay, Presto Blue assay, and Crystal Violet assay). As kresoxym-methyl is associated to boscalid (SDHI) in commercial formulations, we analyzed a potential exacerbation of the induced mitochondrial dysfunction for this combination. For the highest dose at which kresoxym-methyl (5 µM) and boscalid (0.5 µM) did not induce changes in mitochondrial function when used separately, in contrast, when both fungicides were used in combination at the same concentration, we observed a significant alteration of the mitochondrial function of hepatocytes: there was a decrease in oxygen consumption rate, in the ATP level. In addition, the level of mitochondrial superoxide radical anion was increased leading to a decrease in the ratio reduced/oxidized glutathione, and an increase in viability.

Pyraclostrobin induces developmental toxicity and cardiotoxicity through oxidative stress and inflammation in zebrafish embryos

Pyraclostrobin, a typical representative of strobilurin fungicides, is extensively used in agriculture to control fungi and is often detected in water bodies and food. However, the comprehensive toxicological molecular mechanism of pyraclostrobin requires further study. To assess the toxic effects and underlying mechanisms of pyraclostrobin on aquatic organisms, zebrafish embryos were exposed to pyraclostrobin (20, 40, and 60 μg/L) until 96 h post fertilization (hpf). These results indicated that exposure to pyraclostrobin induces morphological alterations, including spinal curvature, shortened body length, and smaller eyes. Furthermore, heart developmental malformations, such as pericardial edema and bradycardia, were observed. This indicated severe cardiotoxicity induced by pyraclostrobin in zebrafish embryos, which was confirmed by the dysregulation of genes related to heart development. Besides, our findings also demonstrated that pyraclostrobin enhanced the contents of reactive oxygen species (ROS) and malondialdehyde (MDA), up-regulated catalase (CAT) activity, but inhibited superoxide dismutase (SOD) activity. Subsequently, the NF-κb signaling pathway was further studied, and the results indicated that the up-regulation of tnf-α, tlr-4, and myd88 activated the NF-κb signaling pathway and up-regulated the relative expression level of pro-inflammatory cytokines, such as cc-chemokine, ifn-γ, and cxcl-clc. Collectively, this study revealed that pyraclostrobin exposure induces developmental toxicity and cardiotoxicity, which may result from a combination of oxidative stress and inflammatory responses. These findings provide a basis for continued evaluation of the effects and ecological risks of pyraclostrobin on the early development of aquatic organisms.

Dissipation and Dietary Risk Assessment of the Fungicide Pyraclostrobin in Apples Using Ultra-High Performance Liquid Chromatography-Mass Spectrometry

The fungicide pyraclostrobin is the main measure used to control apple alternaria blotch in production. To evaluate the potential dietary risks for consumers, the dissipation and terminal residues of pyraclostrobin were investigated using ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS/MS). Pyraclostrobin in apples was extracted by acetonitrile with 2% ammonia and then purified using primary secondary amine (PSA) and graphitized carbon black (GCB). The method showed good linearity within the concentration range of 0.005-0.1 mg L-1, with a coefficient of determination (R2) ≥ 0.9958. The recoveries ranged from 96.0% to 103.8%, with relative standard deviations (RSDs) between 0.8% and 2.3%. The limit of quantification (LOQ) was 0.01 mg kg-1. Pyraclostrobin dispersible oil suspension was applied in 12 apple fields across China according to good agricultural practices (GAPs). In Beijing and Shandong, the dissipation of pyraclostrobin followed first-order kinetic equations, with a half-life of 11 days. The terminal residues ranged from <0.01 to 0.09 mg kg-1. The national estimated daily intake (NEDI) of pyraclostrobin was compared with the acceptable daily intake (ADI), resulting in risk quotient (RQc) of 80.8%. These results suggest that pyraclostrobin poses a low health risk to consumers under GAP conditions and according to recommended dosages.

Synthetic and Natural Antifungal Substances in Cereal Grain Protection: A Review of Bright and Dark Sides

Molds pose a severe challenge to agriculture because they cause very large crop losses. For this reason, synthetic fungicides have been used for a long time. Without adequate protection against pests and various pathogens, crop losses could be as high as 30-40%. However, concerns mainly about the environmental impact of synthetic antifungals and human health risk have prompted a search for natural alternatives. But do natural remedies only have advantages? This article reviews the current state of knowledge on the use of antifungal substances in agriculture to protect seeds against phytopathogens. The advantages and disadvantages of using both synthetic and natural fungicides to protect cereal grains were discussed, indicating specific examples and mechanisms of action. The possibilities of an integrated control approach, combining cultural, biological, and chemical methods are described, constituting a holistic strategy for sustainable mold management in the grain industry.

Biodegradation of the strobilurin fungicide pyraclostrobin by Burkholderia sp. Pyr-1: Characteristics, degradation pathway, water remediation, and toxicity assessment

Pyraclostrobin, a widely used fungicide, poses significant risks to both the environment and human health. However, research on the microbial degradation process of pyraclostrobin was scarce. Here, a pyraclostrobin-degrading strain, identified as Burkholderia sp. Pyr-1, was isolated from activated sludge. Pyraclostrobin was efficiently degraded by strain Pyr-1, and completely eliminated within 6 d in the presence of glucose. Additionally, pyraclostrobin degradation was significantly enhanced by the addition of divalent metal cations (Mn2+ and Cu2+). The degradation pathway involving ether bond and N-O bond cleavage was proposed by metabolite identification. The sodium alginate-immobilized strain Pyr-1 had a higher pyraclostrobin removal rate from contaminated lake water than the free cells. Moreover, the toxicity evaluation demonstrated that the metabolite 1-(4-chlorophenyl)-1H-pyrazol-3-ol significantly more effectively inhibited Chlorella ellipsoidea than pyraclostrobin, while its degradation products by strain Pyr-1 alleviated the growth inhibition of C. ellipsoidea, which confirmed that the low-toxic metabolites were generated from pyraclostrobin by strain Pyr-1. The study provides a potential strain Pyr-1 for the bioremediation in pyraclostrobin-contaminated aquatic environments.

Dissipation, Residue and Human Dietary Risk Assessment of Pyraclostrobin and Cyazofamid in Grapes Using an HPLC-UV Detector

Pyraclostrobin is a new broad-spectrum methoxyacrylic acid fungicide. Cyazofamid is a new selective foliar spray acaricide. Here, we studied the degradation rate and final residues of pyraclostrobin and cyazofamid in grape and evaluated their dietary risk to consumers. The average recoveries of pyraclostrobin ether ester, cyazofamid and cyazofamid metabolite (CCIM) in grapes were 84-94%, 92-98% and 99-104%, respectively. The relative standard deviations (RSDs) were 6.0-20.3%, 2.4-10.5% and 1.3-4.0%, respectively, and the LOQs were all 0.05 mg/kg. The digestion dynamics of the experimental sites were in accordance with the first-order kinetic equation. The degradation half-lives of pyraclostrobin ether ester and cyazofamid were 17.8 d-28.9 d and 4.3 d-7.8 d, respectively. The final residues of pyraclostrobin ether ester, cyazofamid and CCIM in grapes were <0.05-1.88 mg/kg, <0.05-0.31 mg/kg and <0.05-0.47 mg/kg, respectively. Using probability models, the total chronic risk values for pyraclostrobin and cyazofamid were calculated to be 0.112-189.617% and 0.021-1.714%, respectively. The results of the contribution analysis indicate that pyraclostrobin poses a much greater risk to Chinese consumers than cyazofamid, especially to children and adolescents, who have a significantly greater risk than adults. This suggests that more consideration should be given to the cumulative risk of compounds for vulnerable groups in the future.