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

Development and validation of CYP26A1 inhibition assay for high-throughput screening

All-trans retinoic acid (atRA) is an endogenous ligand of the retinoic acid receptors, which heterodimerize with retinoid X receptors. AtRA is generated in tissues from vitamin A (retinol) metabolism to form a paracrine signal and is locally degraded by cytochrome P450 family 26 (CYP26) enzymes. The CYP26 family consists of three subtypes: A1, B1, and C1, which are differentially expressed during development. This study aims to develop and validate a high throughput screening assay to identify CYP26A1 inhibitors in a cell-free system using a luminescent P450-Glo assay technology. The assay performed well with a signal to background ratio of 25.7, a coefficient of variation of 8.9%, and a Z-factor of 0.7. To validate the assay, we tested a subset of 39 compounds that included known CYP26 inhibitors and retinoids, as well as positive and negative control compounds selected from the literature and/or the ToxCast/Tox21 portfolio. Known CYP26A1 inhibitors were confirmed, and predicted CYP26A1 inhibitors, such as chlorothalonil, prochloraz, and SSR126768, were identified, demonstrating the reliability and robustness of the assay. Given the general importance of atRA as a morphogenetic signal and the localized expression of Cyp26a1 in embryonic tissues, a validated CYP26A1 assay has important implications for evaluating the potential developmental toxicity of chemicals.

A comprehensive review on toxicological mechanisms and transformation products of tebuconazole: Insights on pesticide management

Tebuconazole has been widely applied over three decades because of its high efficiency, low toxicity, and broad spectrum, and it is still one of the most popular fungicides worldwide. Tebuconazole residues have been frequently detected in environmental samples and food, posing potential hazards for humans. Understanding the toxicity of pesticides is crucial to ensuring human and ecosystem health, but the toxic mechanisms and toxicity of tebuconazole are still unclear. Moreover, pesticides could transform into transformation products (TPs) that may be more persistent and toxic than their parents. Herein, the toxicities of tebuconazole to humans, mammals, aquatic organisms, soil animals, amphibians, soil microorganisms, birds, honeybees, and plants were summarized, and its TPs were reviewed. In addition, the toxicity of tebuconazole TPs to aquatic organisms and mammals was predicted. Tebuconazole posed potential developmental toxicity, genotoxicity, reproductive toxicity, mutagenicity, hepatotoxicity, neurotoxicity, cardiotoxicity, and nephrotoxicity, which were induced via reactive oxygen species-mediated apoptosis, metabolism and hormone perturbation, DNA damage, and transcriptional abnormalities. In addition, tebuconazole exhibited apparent endocrine-disrupting effects by modulating hormone levels and gene transcription. The toxicity of some TPs was equivalent to and higher than tebuconazole. Therefore, further investigation is necessary into the toxicological mechanisms of tebuconazole and the combined toxicity of a mixture of tebuconazole and its TPs.

Sodium alginate-carboxymethyl chitosan hydrogels loaded with difenoconazole for pH-responsive release to control wheat crown rot

Increasing concern about environmental pollution has driven the development of controlled release formulations for agrochemicals. Due to the advantages of degradability and responsiveness to environmental stimuli, polysaccharide-based hydrogel is an ideal carrier for agrochemicals controlled release. In this study, a method-easy polysaccharide hydrogel for controlled release of difenoconazole (DZ) was prepared with sodium alginate (SA) and carboxymethyl chitosan (CMCS). Due to its three-dimensional crosslinked mesh structure, the prepared hydrogels (CSDZ) showed an agrochemical load capacity of 9.03 % and an encapsulation efficiency of 68.64 %. The release rate is faster in alkaline solution, followed by neutral solution, and slowest in an acid environment, which is consistent with the swelling behavior. Furthermore, leaching studies showed that CSDZ hydrogels have excellent protective properties for encapsulated agrochemicals. Compared with technical DZ, the results of in vitro and pot antifungal testing showed that CSDZ had a better control effect against wheat crown rot (Fusarium pseudograminearum). Safety assessment studies indicated that CSDZ hydrogels exhibit good biocompatibility on nontargeted organisms (Daphnia magna, zebrafish and Eisenia fetida) and wheat. This study aims to provide a potentially promising approach for the preparation and application of biocompatible polysaccharide-based hydrogels for agrochemical-controlled release in sustainable disease management.

In vitro exposure to triazoles used as fungicides impairs human granulosa cells steroidogenesis

Triazoles are the main components of fungicides used in conventional agriculture. Some data suggests that they may be endocrine disruptors. Here, we found five triazoles, prothioconazole, metconazole, difenoconazole, tetraconazole, and cyproconazole, in soil or water from the Centre-Val de Loire region of France. We then studied their effects from 0.001 µM to 1000 µM for 48 h on the steroidogenesis and cytotoxicity of ovarian cells from patients in this region and the human granulosa line KGN. In addition, the expression of the aryl hydrocarbon receptor (AHR) nuclear receptor in KGN cells was studied. Overall, all triazoles reduced the secretion of progesterone, estradiol, or both at doses that were non-cytotoxic but higher than those found in the environment. This was mainly associated, depending on the triazole, with a decrease in the expression of CYP51, STAR, CYP11A1, CYP19A1, or HSD3B proteins, or a combination thereof, in hGCs and KGN cells and an increase in AHR in KGN cells.

Removal of triazole and pyrethroid pesticides from wheat grain by water treatment and ultrasound-supported processes

A simple way to reduce pesticides in cereal grains is to use washing methods. The challenge of this study was to evaluate the effectiveness of reduction of 3 triazole fungicides (difenoconazole, tebuconazole, tetraconazole) and 3 pyrethroid insecticides (beta-cyfluthrin, cypermethrin, deltamethrin) commonly used in wheat protection. Four different pre-washing methods (hot and cold water washing, twice water, and ultrasound-supported washing) were evaluated. The processing factor (PF) was calculated based on the concentration of pesticides determined by LC-MS/MS in the samples of cereal grains before and after the washing process. PFs were within the range 0.01-0.97. Time, teperature and ultrasound were factors influencing the efficiency of water treatment. The study showed that ultrasound-supported washing eliminated pesticide residues to a greater extent than ordinary washing. This process significantly affected or completely reduced concentrations of triazoles in wheat grains. The highest reduction of residues (99%) was received for tebuconazole and ultrasound washing with heating temperature of 60 °C for a total of 10 min. In all washing processes, pyrethroids were removed with lower efficiency than triazoles. The lowest residue reduction was obtained for cypermethrin and washing under cold water for 5 min (3%; PF = 0.97). Beta-Cyfluthrin showed only a 6-27% reduction regardless of the process (PF: 0.73-0.95). Using static analysis, the relationship between the properties of pesticides and the reduction of their concentration in cereals was clarified and showed a strong correlation.

Evaluating non-targeted analysis methods for chemical characterization of organic contaminants in different matrices to estimate children's exposure

BACKGROUND

Children are vulnerable to environmental exposure of contaminants due to their small size, lack of judgement skills, as well as their proximity to dust, soil, and other environmental sources. A better understanding about the types of contaminants that children are exposed to or how their bodies retain or process these compounds is needed.

OBJECTIVE

In this study, we have implemented and optimized a methodology based on non-targeted analysis (NTA) to characterize chemicals in dust, soil, urine, and in the diet (food and drinking water) of infant populations.

METHODS

To evaluate potential toxicological concerns associated with chemical exposure, families with children between 6 months and 6 years of age from underrepresented groups were recruited in the greater Miami area. Samples of soil, indoor dust, food, water, and urine were provided by the caregivers, prepared by different techniques (involving online SPE, ASE, USE, QuEChERs), and analyzed by liquid chromatography-high resolution mass spectrometry (LC-HRMS). Data post-processing was performed using the small molecule structure identification software, Compound Discoverer (CD) 3.3, and identified features were plotted using Kendrick mass defect plot and Van Krevelen diagrams to show unique patterns in different samples and regions of anthropogenic compound classifications.

RESULTS

The performance of the NTA workflow was evaluated using quality control standards in terms of accuracy, precision, selectivity, and sensitivity, with an average of 98.2%, 20.3%, 98.4% and 71.1%, respectively. Sample preparation was successfully optimized for soil, dust, water, food, and urine. A total of 30, 78, 103, 20 and 265 annotated features were frequently identified (detection frequency >80%) in the food, dust, soil, water, and urine samples, respectively. Common features detected in each matrix were prioritized and classified, providing insight on children's exposure to organic contaminants of concern and their potential toxicities.

IMPACT STATEMENT

Current methods to assess the ingestion of chemicals by children have limitations and are generally restricted by specific classes of targeted organic contaminants of interest. This study offers an innovative approach using non-targeted analysis for the comprehensive screening of organic contaminants that children are exposed to through dust, soil, and diet (drinking water and food).

Impact of technological processes on tebuconazole reduction in selected cereal species and the primary cereal product, and dietary exposure assessment

Contamination of cereals with tebuconazole (TEB) can affect the dietary risk assessment. This study investigates, for the first time, how mechanical, thermal, physical-chemical, and biochemical processes affect the TEB level in wheat, rye, and barley. The biochemical process of malting was the most effective for tebuconazole reduction (by 86%) in cereals. Thermal processes were also effective, i.e., boiling (70%) and baking (55%). These processes considerably decreased the concentration of tebuconazole, and Procesing Factors (PFs) were from 0.10 to 0.18 (malting), 0.56 to 0.89 (boiling), and 0.44 to 0.45 (baking), respectively. The concentration of TEB was not reduced after the application of mechanical processing. The risk was estimated in dietary exposure assessment on the basis of the highest reported levels of tebuconazole residues bread. At a high level of rye bread consumption, the potential exposure to tebuconazole reached only 3.5% and 2.7% in children and adults, respectively.

Gold-based lateral-flow strip for the detection of penconazole in watermelon and cucumber samples

As a typical triazole fungicide, penconazole (PEN) is widely used in agriculture but has been proven to be toxic. In this study, we designed a new hapten to prepare a highly sensitive and specific anti-PEN monoclonal antibody (mAb) and established a gold nanoparticle-based lateral-flow immunoassay (LFIA) for the detection of PEN residues in watermelon and cucumber. The 50% inhibitory concentration (IC50) of the mAb was 0.42 ng/mL and the LFIA strip had a visual limit of detection (vLOD) of 2.5 ng/g and a cut-off value of 10 ng/g in watermelon and cucumbers. The calculated limit of detection (LOD) of the LFIA strip was 0.36 ng/g for watermelon and 0.29 ng/g for cucumber. The LFIA strip also gave a recovery rate of 92.5–109.0% for watermelon samples and 92.5–106.7% for cucumber samples. These results using the LFIA strip are highly consistent with those seen using LC-MS/MS. Thus our developed LFIA strip represents a potentially reliable tool for the rapid on-site screening for PEN in watermelons and cucumbers..