Stereoselectivity in bioaccumulation and excretion of epoxiconazole by mealworm beetle (Tenebrio molitor) larvae

Hormesis of black soldier fly larva: Influence and interactions in livestock manure recycling

Black soldier fly larvae (BSFL) are considered important organisms, utilized as tools to transform waste including manure into valuable products. The growth and cultivation of BSFL are influenced by various factors, such as the presence of toxic substances in the feed and parasites. These factors play a crucial role in hormesis, and contributing to regulate these contaminants hermetic doses to get sustainable byproducts. This review aims to understand the effects on BSFL growth and activities in the presence of compounds like organic and inorganic pollutants. It also assesses the impact of microbes on BSFL growth and explores the bioaccumulation of pharmaceutical compounds, specifically focusing on heavy metals, pesticides, pharmaceuticals, indigenous bacteria, insects, and nematodes. The review concludes by addressing knowledge gaps, proposing future biorefineries, and offering recommendations for further research.

Absorption, distribution, metabolism, and elimination of epoxiconazole enantiomers in lizards (Eremias argus)

Epoxiconazole (EPX) is a world widely used chiral triazole fungicide in the agriculture field. The excessive application of this triazole may cause damage to lizards. However, limited information is known about the toxicokinetics of EPX on lizards. Our study aimed to investigate the enantioselective absorption, distribution, metabolism, and elimination (ADME) of EPX in lizards following low and high dose exposure (10 and 100 mg kg-1 bodyweitht (bw)). The results demonstrated that (+)-EPX was easier absorbed than (-)-EPX in lizard plasma. Both (+)-EPX and (-)-EPX were detected in the liver, gonad, kidney, skin, brain, and intestine, with (+)-EPX preferentially distributed in these tissues. The elimination of (-)-EPX was faster than that of (+)-EPX in lizard liver and kidney in the high dose groups. Chiral conversion was found between EPX enantiomers in lizard skin. Simultaneously, five metabolites including M2, M4, M10, M18 and M19 were detected in lizard liver and kidney after EPX enantiomers exposure. The relative concentrations of M2, M4, and M10 were higher in the liver and kidney of (-)-EPX groups than those produced from (+)-EPX groups. The metabolic enzymes CYP3A4 and SULT1A1 primarily mediated enantioselective metabolism of EPX. The conclusions drawn from this study significantly enhance our understanding of the enantioselective behaviors of chiral triazole fungicides in reptiles, offering essential guidance for assessing the risks associated with different enantiomers of triazole fungicides.

Transfer and bioaccumulation of pesticides in terrestrial arthropods and food webs: State of knowledge and perspectives for research

Arthropods represent an entry point for pesticide transfers in terrestrial food webs, and pesticide accumulation in upper chain organisms, such as predators can have cascading consequences on ecosystems. However, the mechanisms driving pesticide transfer and bioaccumulation in food webs remain poorly understood. Here we review the literature on pesticide transfers mediated by terrestrial arthropods in food webs. The transfer of pesticides and their potential for bioaccumulation and biomagnification are related to the chemical properties and toxicokinetic of the substances, the resistance and detoxification abilities of the contaminated organisms, as well as by their effects on organisms' life history traits. We further identify four critical areas in which knowledge gain would improve future predictions of pesticides impacts on terrestrial food webs. First, efforts should be made regarding the effects of co-formulants and pesticides mixtures that are currently understudied. Second, progress in the sensitivity of analytical methods would allow the detection of low concentrations of pesticides in small individual arthropods. Quantifying pesticides in arthropods preys, their predators, and arthropods or vertebrates at higher trophic level would bring crucial insights into the bioaccumulation and biomagnification potential of pesticides in real-world terrestrial food webs. Finally, quantifying the influence of the trophic structure and complexity of communities on the transfer of pesticides could address several important sources of variability in bioaccumulation and biomagnification across species and food webs. This narrative review will inspire future studies aiming to quantify pesticide transfers in terrestrial food webs to better capture their ecological consequences in natural and cultivated landscapes.

Quantitative assessment of selective degradation behavior of etoxazole in different classes of organisms by compound-specific isotope analysis

In this paper, the stereoselective degradation and quantitative identification of chiral pesticide etoxazole in organisms with different classes of organisms (soil, chlorella algal fluid and mice) were carried out by compound-specific isotope analysis (CSIA). The degradation behavior and stable isotope fractionation effect of etoxazole in soil, chlorella and mice were investigated. The R-etoxazole degraded faster than S-etoxazole in different classes of organisms. The metabolites M1, M2 and M3 were detected in all three substrates. Biodegradation is the main factor for the change of stable isotope ratio of chiral pesticide etoxazole. Furthermore, the relationship between fractionation value of carbon isotope and residual concentration of etoxazole is established by Rayleigh equation, and the biodegradation rate of etoxazole could be calculated by using CSIA without measuring the concentration of etoxazole. Therefore, the use of CSIA can accurately assess the degradation behavior of pesticide pollution in the environment and provide a certain scientific evidence and technical support in the process of environmental remediation.

Widespread triazole pesticide use affects infection dynamics of a global amphibian pathogen

The sixth mass extinction is a consequence of complex interplay between multiple stressors with negative impact on biodiversity. We here examine the interaction between two globally widespread anthropogenic drivers of amphibian declines: the fungal disease chytridiomycosis and antifungal use in agriculture. Field monitoring of 26 amphibian ponds in an agricultural landscape shows widespread occurrence of triazole fungicides in the water column throughout the amphibian breeding season, together with a negative correlation between early season application of epoxiconazole and the prevalence of chytrid infections in aquatic newts. While triazole concentrations in the ponds remained below those that inhibit growth of Batrachochytrium dendrobatidis, they bioaccumulated in the newts' skin up to tenfold, resulting in cutaneous growth-suppressing concentrations. As such, a concentration of epoxiconazole, 10 times below that needed to inhibit fungal growth, prevented chytrid infection in anuran tadpoles. The widespread presence of triazoles may thus alter chytrid dynamics in agricultural landscapes.

Accumulation, metabolites formation and elimination behavior of rac-glufosinate-ammonium and glufosinate-P in zebrafish (Danio rerio)

•

Zebrafish samples were purified with diatomaceous earth, CH₂Cl₂ and Oasis PRiME HLB SPE column.

•

The bioaccumulation of glufosinate in zebrafish is enantioselective.

•

The accumulation of glufosinate-P in zebrafish was greater than that of rac-glufosinate.

•

The elimination half-life of glufosinate in zebrafish is less than 2.3 d.

•

NAG and MPP produced in fish was not over 4% of the parent culture concentration.

An efficient trace detection method for the determination of residues of the glufosinate enantiomers and metabolites in zebrafish by HPLC–Q-Exactive Orbitrap Mass Spectrometry was developed. After the purification of dichloromethane and Oasis PRiME HLB SPE column, the recovery ranges from 77% to 104%, with RSD < 10.03%. The limits of quantitation in zebrafish were 0.006–0.02 mg/kg. The results revealed zebrafish absorbed glufosinate slowly, reaching a steady state in 10–14 days, and the bioaccumulation factor (BCF) of D/L-glufosinate-ammonium was less than 0.3. L-glufosinate-ammonium accumulated preferentially in zebrafish. The residue of the metabolite N-acetyl glutamate (NAG) was smaller than that of 3-methyl phosphonic acid (MPP). D/L-glufosinate-ammonium had an elimination half-life of less than 2.3 days during the elimination phase. The bioaccumulation and elimination behavior of glufosinate-ammonium in zebrafish aquatic system was shown in this work, which offered scientific data for assessing the food safety of rac-glufosinate-ammonium and glufosinate-P (pure L-glufosinate-ammonium) in fish.

Environmental behavior of the chiral fungicide epoxiconazole in earthworm-soil system: Enantioselective enrichment, degradation kinetics, chiral metabolite identification, and biotransformation mechanism

The environmental impact of the chiral fungicide epoxiconazole and its chiral transformation products (TPs) on non-target organisms and the environment has become a significant concern due to its widespread use in agricultural practice. Enantioselectivity studies of parent contaminants cannot adequately assess the complexity of its chiral TPs in the environment. This study aimed to investigate the environmental behavior of epoxiconazole in an earthworm-soil system. 2S,3R-(-)-epoxiconazole was preferentially enriched in earthworms during the accumulation phase (p < 0.05), but no enantioselectivity was observed during the elimination phase. One methoxylated and four hydroxylated chiral TPs were identified in soil, earthworm, and excrement. The epoxy ring hydroxylated TP and methoxylated TP of epoxiconazole were discovered for the first time in the environment. The chemically specific enantioselectivity with enantiomer fraction (EF) > 0.8 was observed for the TPs in different matrices. The CYP450 monooxygenase of earthworm was significant activated. In vitro enzyme metabolism experiments (earthworm microsomes and recombinant CYP450 enzymes CYP2A6, CYP 2C9, and CYP 3A4) were carried out to further explain the biotransformation mechanism of epoxiconazole in earthworm. This study provides new evidence of enantiomeric biotransformation of chiral fungicide epoxiconazole in the earthworm-soil system and could provide valuable insights into their environmental risk assessment.

Subchronic exposure to Epoxiconazole induced-heart damage in male Wistar rats

Epoxiconazole is a worldwide fungicide used to control fungal diseases. Although to its hazardous effects in non-target species, little information is available in the literature to show the cardiotoxic effects of EPX in male rats. Thus, our investigation aimed to assess the outcomes of EPX exposure on some biochemical parameters, the generation of oxidative stress, DNA fragmentation and histopathological alterations in the heart tissue. EPX was administered orally at doses of 8, 24, 40 and 56 mg/kg body weight, representing, respectively NOEL (No observed effect level), NOEL× 3, NOEL× 5 and NOEL× 7 for 28 consecutive days in male Wistar rats. Our results show that EPX induced a significant decrease of cardiac acetylcholinesterase, an increase of biochemical markers, such as creatinine phosphokinase (CPK) and a perturbation of the lipid profile. Furthermore, EPX caused diverse histological modifications in the myocardium, including congestion of cardiac blood vessels, cytoplasmic vacuolization, leucocytic infiltration and hemorrhage. Indeed, we have shown that EPX induces increase of lipid peroxidation, protein oxidation levels and DNA damage. On the other hand, we have found an increase of the antioxidant enzymes activity such as catalase (CAT) and superoxide dismutase (SOD) activities. The glutathione peroxidase and glutathione S tranferase initially enhanced at the doses of 8, 24, and 40 mg/kg b.w. and then decreased at the dose of 56 mg/kg b.w. In conclusion, our work has shown that EPX causes cardiotoxic effects by altering redox status and damaging heart tissue.

Bioaccumulation, metabolism and endocrine-reproductive effects of metolachlor and its S-enantiomer in adult zebrafish (Danio rerio)

The aim of the present study was to evaluate the enantioselective bioaccumulation, metabolism, and toxic effects of metolachlor and S-metolachlor in zebrafish. Five-month-old zebrafish were exposed to metolachlor and S-metolachlor for 28 days, then transferred to clean water and purified for 7 days. In the uptake phase, S-metolachlor was preferentially accumulated at low concentrations, while metolachlor was preferentially accumulated at high concentrations. The two chemicals were metabolized by >70% in zebrafish on the first day and showed same metabolic process. At the accumulation endpoint, S-metolachlor had no significant inhibitory effect on the enzymes activities of superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) and developmental indicators of zebrafish. However, 300 μg/L metolachlor significantly inhibited the enzymes activities of SOD, CAT and GST and affected the liver development. The preferential enrichment of metolachlor at the high concentration may be the reason for its higher toxicity to zebrafish. Further research demonstrated that metolachlor significantly altered the expression of hypothalamic-pituitary-gonadal (HPG) axis-related genes, including gnrh2, gnrh3, lhβ, 17βhsd and cyp19a, thereby reducing the levels of testosterone (T) in females and sex hormones (estradiol and testosterone) in males. S-metolachlor increased the levels of estradiol (E2) in females by altering the expression of HPG axis-related genes such as fshβ, cyp17, 17βhsd and cyp19a. The mechanism of metolachlor and S-metolachlor on the endocrine disrupting effects of zebrafish is different, which may be sex-specific. 7 days after transferring the exposed zebrafish to clean water, most of the enzymes activities, sex hormone levels and related gene expression levels returned to normal, which may be related to the rapid metabolism of the two chemicals.

Changes in soil and rat gut microbial diversity after long-term exposure to the chiral fungicide epoxiconazole

In previous articles, it was found that epoxiconazole enantiomers can persist for a long time in the environment, causing severe environmental damage. Herein, we investigated alterations in the soil microbial community and rat gut microbiota after six weeks of treatment with rac-epoxiconazole or one of its enantiomers. The selected concentrations were 1, 2, and 6 times greater than the maximum residue limits (MRLs). The rat gut microbiota relative abundance in the feces significantly changed following exposure to rac-epoxiconazole or one of its enantiomers. At the phylum level, in the R,S-, S,R-epoxiconazole, and rac-treated groups, Firmicutes presented the greatest decrease in abundance; however, Spirochaetes presented the greatest increase in abundance in the rac- and S,R-epoxiconazole-treated groups. In response to R,S-epoxiconazole, Epsilonbacteraeota presented the greatest increase in abundance. In soil samples treated with epoxiconazole, the relative abundance of the soil bacterial community also changed. Proteobacteria presented the greatest decrease in abundance in the S,R- and rac-treated samples. However, Firmicutes presented the greatest increase in abundance. In the R,S-treated soil samples, the situation was the opposite. In general, prolonged exposure to epoxiconazole at high concentrations could initiate noticeable alterations in rat gut microbiota and soil microbial diversity. R,S-epoxiconazole had improved bioactivity and less toxic effects at relatively low concentrations. Therefore, we recommend using R,S-epoxiconazole at a relatively low concentration, which is better for environmental safety.

Neuroprotective effects of Myricetin on Epoxiconazole-induced toxicity in F98 cells

Epoxiconazole is one of the most commonly used fungicides in the world. The exposition of humans to pesticides is mainly attributed to its residue in food or occupational exposure in agricultural production. Because of its lipophilic character, Epoxiconazole can accumulate in the brain Heusinkveld et al. (2013) [1]. Consequently, it is urgent to explore efficient strategies to prevent or treat Epoxiconazole-related brain damages. The use of natural molecules commonly found in our diet represents a promising avenue. Flavonoids belong to a major sub-group compounds possessing powerful antioxidant activities based on their different structural and sterical properties [2]. We choose to evaluate Myricetin, a flavonoid with a wide spectrum of pharmacological effects, for its possible protective functions against Epoxiconazole-induced toxicities. The cytotoxicity induced by this fungicide was evaluated by the cell viability, cell cycle arrest, ROS generation, antioxidant enzyme activities, and Malondialdehyde production, as previously described in Hamdi et al., 2019 [3]. The apoptosis was assessed through the evaluation of the mitochondrial transmembrane potential (ΔΨm), caspases activation, DNA fragmentation, cytoskeleton disruption, nuclear condensation, appearance of sub-G0/G1 peak (fragmentation of the nucleus) and externalization of Phosphatidylserine. This study indicates that pre-treatment of F98 cells with Myricetin during 2 h before Epoxiconazole exposure significantly increased the survival of cells, restored DNA synthesis of the S phase, abrogated the ROS generation, regulated the activities of Catalase (CAT) and Superoxide Dismutase (SOD), and reduced the MDA level. The loss of mitochondrial membrane potential, DNA fragmentation, cytoskeleton disruption, chromatin condensation, Phosphatidylserine externalization, and Caspases activation were also reduced by Myricetin. Together, these findings indicate that Myricetin is a powerful natural product able to protect cells from Epoxiconazole-induced cytotoxicity and apoptosis.

A review on the stereospecific fate and effects of chiral conazole fungicides

The production and use of chiral pesticides are triggered by the need for more complex molecules capable of effectively combating a greater spectrum of pests and crop diseases, while sustaining high production yields. Currently, chiral pesticides comprise about 30% of all pesticides in use; however, some pesticide groups such as conazole fungicides (CFs) consist almost exclusively of chiral compounds. CFs are produced and field-applied as racemic (1:1) mixtures of two enantiomers (one chiral center in the molecule) or four diastereoisomers, i.e., two pairs of enantiomers (two chiral centers in the molecule). Research on the stereoselective environmental behavior and effects of chiral pesticides such as CFs has become increasingly important within the fields of environmental chemistry and ecotoxicology. This is motivated by the fact that currently, the fate and effects of chiral pesticides such as CFs that arise due to their stereoselectivity are not fully understood and integrated into risk assessment and regulatory decisions. In order to fill this gap, a summary of the state-of-the-art literature related to the stereospecific fate and effects of CFs is needed. This will also benefit the agrochemistry industry as they enhance their understanding of the environmental implications of CFs which will aid future research and development of chiral products. This review provides a collection of >80 stereoselective studies for CFs related to chiral analytical methods, fungicidal activity, non-target toxicity, and behavior of this broadly used pesticide class in the soil environment. In addition, the review sheds more light on mechanisms behind stereoselectivity, considers possible agricultural and environmental implications, and suggests future directions for the safe use of chiral CFs and the reduction of their environmental footprint.

Liquid Chromatography-Tandem Mass Spectrometry for the Simultaneous Analysis of 353 Pesticides in the Edible Insect Tenebrio molitor Larvae (Mealworms)

Tenebrio molitor larvae (mealworm) is an edible insect and is considered a future food. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), a novel method for simultaneous analysis of 353 target analytes was developed and validated. Various sample preparation steps including “quick, easy, cheap, effective, rugged, and safe” (QuEChERS) extraction conditions, number of acetonitrile-hexane partitions, and dispersive-solid phase extraction (dSPE) sorbents were compared, and the optimal conditions were determined. In the established method, 5 g of homogenized mealworms was extracted with acetonitrile and treated with QuEChERS EN 15662 salts. The crude extract was subjected to three rounds of acetonitrile-hexane partitioning, and the acetonitrile layer was cleaned with C18 dSPE. The final solution was matrix-matched and injected into LC-MS/MS (2 μL). For target analytes, the limits of quantitation (LOQs) were ≤10 μg/kg, and the correlation coefficient (r²) of calibration was >0.990. In recovery tests, more than 90% of the pesticides showed an excellent recovery range (70–120%) with relative standard deviation (RSD) ≤20%. For more than 94% of pesticides, a negligible matrix effect (within ±20%) was observed. The analytical method was successfully applied and used for the detection of three urea pesticides in 4 of 11 mealworm samples.

Enantioselective behaviors of cis-epoxiconazole in vegetables-soil-earthworms system by liquid chromatography-quadrupole-time-of-flight mass spectrometry

Cis-epoxiconazole is a widely used triazole fungicide for control and prevention of a series of fungal diseases in fruits, vegetables, teas and grains. The present work aimed at exploring enantioselective behavior of cis-epoxiconazole in the vegetable-soil-earthworm system. Firstly, the absolute configuration of cis-epoxiconazole enantiomers was ascertained. Secondly, enantioselective degradation of cis-epoxiconazole in cabbage, pakchoi and pepper were performed under field trials, which has not been previously reported. Enantioselective degradation occurred in cabbage and pepper samples. 2R, 3S-(+)-cis-epoxiconazole was degraded faster than 2S, 3R-(-)-cis-epoxiconazole in cabbage, while the reversed results were obtained in pepper. No enantioselective degradation was observed in pakchoi. Finally, soil is the principal reservoir of environmental pesticides, so the enantioselective behaviors of cis-epoxiconazole in soil and soil organism (earthworm, Eisenia fetida) were evaluated. Similar bioaccumulation curves in earthworms and degradation curves in soil were observed under the exposure levels of 1 and 10 mg/kg. Accumulation factors (AFs) indicated earthworms had weak bioaccumulation potential to cis-epoxiconazole in the contaminated soil, and no obvious enantioselectivity was observed. The different enantioselectivities in different vegetables illuminated that preferentially enriched enantiomer might impose higher risk on human health than the other one, and the high risk enantiomer required further assessment. These results may reduce the uncertainty of cis-epoxiconazole to the environmental risk assessment.

Enantioselectivity in biotransformation and bioaccumulation processes of typical chiral contaminants

Chirality is a critical topic in the medicinal and agrochemical fields. One quarter of all agrochemicals was chiral in 1996, and this proportion has increased remarkably with the introduction of new compounds over time. Despite scientists have made great efforts to probe the enantiomeric selectivity of chiral chemicals in the environment since early 1990s, the different behaviours of individual enantiomers in biologically mediated processes are still unclear. In the present review, we highlight state-of-the-knowledge on the stereoselective biotransformation and accumulation of chiral contaminants in organisms ranging from invertebrates to humans. Chiral insecticides, fungicides, and herbicides, polychlorinated biphenyls (PCBs), pharmaceuticals, flame retardants hexabromocyclododecane (HBCD), and perfluorooctane sulfonate (PFOS) are all included in the target compounds. Key findings included: a) Changes in the enantiomeric fractions in vitro and in vivo models revealed that enantioselectivity commonly occurs in biotransformation and bioaccumulation. b) Emerging contaminants have become more important in the field of enantioselectivity together with their metabolites in biological transformation process. c) Chiral signatures have also been regarded as powerful tools for tracking pollution sources when the contribution of precursor is unknown. Future studies are needed in order to understand not only preliminary enrichment results but also detailed molecular mechanisms in diverse models to comprehensively understand the behaviours of chiral compounds.

Chiral bioaccumulation behavior of tebuconazole in the zebrafish (Danio rerio)

Tebuconazole is an effective chiral fungicide, and previous studies have demonstrated that tebuconazole enantiomers exhibit enantioselective toxicity to non-target aquatic organisms. Thus, the aim of the present study was to investigate the chiral bioaccumulation behavior of tebuconazole in zebrafish (Danio rerio). Two exposure concentrations (0.107 and 1.07 mg/L) of tebuconazole were used. The uptake experiments lasted for 8 days, and subsequently, the zebrafish were transferred to another clean tank containing water without tebuconazole for depuration experiments (up to 14 days). A significant trend in enantioselective bioaccumulation was observed in these zebrafish with the preferential accumulation of (-)-R-tebuconazole at two dose levels. The results of the depuration experiments indicated that the degradation of (-)-R-tebuconazole in zebrafish was slower than that of (+)-S-tebuconazole. The BCFk values for (+)-S-tebuconazole and (-)-R-tebuconazole in a low dose of this chemical were 11.22 and 16.25, respectively, while at a high dose, these values were 9.79 and 10.31, respectively. The enantiomer fraction of tebuconazole in zebrafish and water ranged from 0.31-0.49. Hence, future research should focus on the fate of tebuconazole in the aquatic environment at the enantiomer levels.