Old pesticide, new use: Smart and safe enantiomer of isocarbophos in locust control

The association of isocarbophos and isofenphos with different types of glucose metabolism: The role of inflammatory cells

To investigate the associations between isocarbophos and isofenphos with impaired fasting glucose (IFG) and type 2 diabetes mellitus (T2DM), and to assess the mediation roles of inflammation cells. There were 2701 participants in the case-control study, including 896 patients with T2DM, 900 patients with IFG, 905 subjects with NGT. Plasma isocarbophos and isofenphos concentrations were measured using gas chromatography and triple quadrupole tandem mass spectrometry. Generalized linear models were used to calculate the relationships between plasma isofenphos and isocarbophos levels with inflammatory factor levels and T2DM. Inflammatory cell was used as mediators to estimate the mediating effects on the above associations. Isocarbophos and isofenphos were positively related with T2DM after adjusting for other factors. The odds ratio (95% confidence interval) (OR (95%CI)) for T2DM was 1.041 (1.015, 1.068) and for IFG was 1.066 (1.009, 1.127) per unit rise in ln-isocarbophos. The prevalence of T2DM increased by 6.4% for every 1 unit more of ln-isofenphos (OR (95% CI): 1.064 (1.041, 1.087)). Additionally, a 100% rise in ln-isocarbophos was linked to 3.3% higher ln-HOMA2IR and a 0.029 mmol/L higher glycosylated hemoglobin (HbA1c) (95% CI: 0.007, 0.051). While a 100% rise in ln-isofenphos was linked to increase in ln-HOMA2 and ln-HOMA2IR of 5.8% and 3.4%, respectively. Furthermore, white blood cell (WBC) and neutrophilic (NE) were found to be mediators in the relationship between isocarbophos and T2DM, and the corresponding proportions were 17.12% and 17.67%, respectively. Isofenphos and isocarbophos are associated with IFG and T2DM in the rural Chinese population, WBC and NE have a significant role in this relationship.

Behavioral toxicity of TDCPP in marine zooplankton: Evidence from feeding and swimming responses, molecular dynamics and metabolomics of rotifers

As new organic flame retardants, chlorinated organophosphate esters (Cl-OPEs) have high water solubility and structural similarity to organophosphate pesticides, posing risks to aquatic organisms. The potential neurotoxicity of Cl-OPEs has attracted attention, especially in marine invertebrates with a relatively simple nervous system. In this study, a marine rotifer with a cerebral ganglion, Brachionus plicatilis, was exposed to tris (1,3-dichloro-2-propyl) phosphate (TDCPP) (two environmental concentrations and one extreme level), and the changes in feeding and swimming behaviors and internal mechanism were explored. Exposure to 1.05 nM TDCPP did not change the filtration and ingestion rates of rotifers and average linear velocity. But 0.42 and 4.20 μM TDCPP inhibited these three parameters and reduced unsaturated fatty acid content, reproduction and population growth. All TDCPP test concentrations suppressed AChE activity, causing excessive accumulation of acetylcholine within rotifers, thereby disturbing the neural innervation of corona cilia. Molecular docking and molecular dynamics revealed that this inhibition was because TDCPP can bind to the catalytic active site of rotifer AChE through van der Waals forces and electrostatic interactions. TRP420 was the leading amino residue in the binding, and GLY207 contributed to a hydrogen bond. Nontargeted metabolomics using LC-MS and GC-MS identified differentially expressed metabolites in TDCPP treatments, mainly from lipid and lipid-like molecules, especially sphingolipids. TDCPP decreased ganglioside content but stimulated ceramide generation and the expression levels of 3 genes related to ceramide de novo synthesis. The mitochondrial membrane potential (MMP) and ATP content decreased, and the electron respiratory chain complex and TCA cycle were deactivated. An inhibitor of ceramide synthase, fumonisin, alleviated MMP and ATP, implying a critical role of ceramide in mitochondrial dysfunction. Thus, TDCPP exposure caused an energy supply deficit affecting ciliary movement and ultimately inhibiting rotifer behaviors. Overall, this study promotes the understanding of the neurotoxicity of Cl-OPEs in marine invertebrates.

Enantioselectivity effects of energy metabolism in honeybees (Apis mellifera) by triticonazole

The heavy use of agrochemicals is considered a major factor contributing to the decline in wild honeybee populations. Development of low-toxicity enantiomers of chiral fungicides is the key to reducing the potential threats to honeybees. In this study, we evaluated the enantioselective toxic effects of triticonazole (TRZ) on honeybees and its molecular mechanisms. The results showed that after long-term exposure to TRZ, the content of thoracic ATP decreased significantly, by 41 % in R-TRZ treatments and by 46 % in S-TRZ treatments. Furthermore, the transcriptomic results indicated that S-TRZ and R-TRZ significantly altered the expression of 584 genes and 332 genes, respectively. Pathway analysis indicated that R- and S-TRZ could affect different genes expressed in GO terms and metabolic pathways, especially the transport GO terms (GO: 0006810) and pathways of alanine, aspartate and glutamate metabolism, drug metabolism - cytochrome P450, and pentose phosphate. Additionally, S-TRZ had a more pronounced effect on honeybee energy metabolism, disrupting a greater number of genes involved in the TCA cycle and glycolysis/glycogenesis, exerting a stronger effect on energy metabolic pathways, including nitrogen metabolism, sulfur metabolism, and oxidative phosphorylation. In summary, we recommend reducing the proportion of S-TRZ in racemate to minimize the threat to the survival of honeybees and protect the diversity of economic insects.

Dissecting the Enantioselective Neurotoxicity of Isocarbophos: Chiral Insight from Cellular, Molecular, and Computational Investigations

Chiral organophosphorus pollutants are found abundantly in the environment, but the neurotoxicity risks of these asymmetric chemicals to human health have not been fully assessed. Using cellular, molecular, and computational toxicology methods, this story is to explore the static and dynamic toxic actions and its stereoselective differences of chiral isocarbophos toward SH-SY5Y nerve cells mediated by acetylcholinesterase (AChE) and further dissect the microscopic basis of enantioselective neurotoxicity. Cell-based assays indicate that chiral isocarbophos exhibits strong enantioselectivity in the inhibition of the survival rates of SH-SY5Y cells and the intracellular AChE activity, and the cytotoxicity of (S)-isocarbophos is significantly greater than that of (R)-isocarbophos. The inhibitory effects of isocarbophos enantiomers on the intracellular AChE activity are dose-dependent, and the half-maximal inhibitory concentrations (IC₅₀) of (R)-/(S)-isocarbophos are 6.179/1.753 μM, respectively. Molecular experiments explain the results of cellular assays, namely, the stereoselective toxic actions of isocarbophos enantiomers on SH-SY5Y cells are stemmed from the differences in bioaffinities between isocarbophos enantiomers and neuronal AChE. In the meantime, the modes of neurotoxic actions display that the key amino acid residues formed strong noncovalent interactions are obviously different, which are related closely to the molecular structural rigidity of chiral isocarbophos and the conformational dynamics and flexibility of the substrate binding domain in neuronal AChE. Still, we observed that the stable "sandwich-type π-π stacking" fashioned between isocarbophos enantiomers and aromatic Trp-86 and Tyr-337 residues is crucial, which notably reduces the van der Waals' contribution (ΔG_vdW) in the AChE-(S)-isocarbophos complexes and induces the disparities in free energies during the enantioselective neurotoxic conjugations and thus elucidating that (S)-isocarbophos mediated by synaptic AChE has a strong toxic effect on SH-SY5Y neuronal cells. Clearly, this effort can provide experimental insights for evaluating the neurotoxicity risks of human exposure to chiral organophosphates from macroscopic to microscopic levels.

Enzyme Inhibition-Based Assay to Estimate the Contribution of Formulants to the Effect of Commercial Pesticide Formulations

Pesticides can affect the health of individual organisms and the function of the entire ecosystem. Therefore, thorough assessment of the risks associated with the use of pesticides is a high-priority task. An enzyme inhibition-based assay is used in this study as a convenient and quick tool to study the effects of pesticides at the molecular level. The contribution of formulants to toxicological properties of the pesticide formulations has been studied by analyzing effects of 7 active ingredients of pesticides (AIas) and 10 commercial formulations based on them (AIfs) on the function of a wide range of enzyme assay systems differing in complexity (single-, coupled, and three-enzyme assay systems). Results have been compared with the effects of AIas and AIfs on bioluminescence of the luminous bacterium Photobacterium phosphoreum. Mostly, AIfs produce a considerably stronger inhibitory effect on the activity of enzyme assay systems and bioluminescence of the luminous bacterium than AIas, which confirms the contribution of formulants to toxicological properties of the pesticide formulation. Results of the current study demonstrate that "inert" ingredients are not ecotoxicologically safe and can considerably augment the inhibitory effect of pesticide formulations; therefore, their use should be controlled more strictly. Circular dichroism and fluorescence spectra of the enzymes used for assays do not show any changes in the protein structure in the presence of commercial pesticide formulations during the assay procedure. This finding suggests that pesticides produce the inhibitory effect on enzymes through other mechanisms.

Enantioselectivity in the toxicological effects of chiral pesticides: A review

As a special category of pesticides, chiral pesticides have increased the difficulty in investigating pesticide toxicity. Based on their usage, chiral pesticides can be divided into insecticides, herbicides, and fungicides. Over the past decades, great efforts have been made on elucidating their toxicological effects. However, no literature has reviewed the enantioselective toxicity of chiral pesticides since 2014. In recent years, more chiral pesticides have been registered for application. As such, huge research progresses have been achieved in enantioselective toxicity of chiral pesticides. Generally, more researches have remedied the knowledge gap in toxicological effects of old and new chiral pesticides. And the toxicological endpoints being evaluated have become more specific rather than centering on basic toxicity and target organisms. Besides, the underlying mechanisms accounting for the enantioselectivity in toxicological effects of chiral pesticides have been discussed as well. All in all, this review provides the critical knowledge for risk assessments, and help to drive the green-technology of single- or enriched-enantiomer pesticides and formulation of relevant laws and regulations.

Triticonazole enantiomers induced enantioselective metabolic phenotypes in Fusarium graminearum and HepG2 cells

The management of Fusarium head blight relies heavily on triazole fungicides. Most of triazole fungicides are chiral, and their enantioselective effects on metabolic phenotypes are poorly understood. Herein, we analyzed the bioactivity of triticonazole against Fusarium graminearum, and ¹H-nuclear magnetic resonance-based metabolomics was used to assess the metabolic disturbances of triticonazole enantiomers in Fusarium graminearum and human hepatocarcinoma cells. Results indicated that the bioactivity of R-triticonazole was 4.28-fold higher than its antipode since it bound stronger with fungal CYP51B and induced more abnormal metabolic processes of Fusarium graminearum, including lipid metabolism, glycolysis, and amino acid metabolism. In human hepatocarcinoma cells, pathways of "alanine, aspartic acid and glutamate metabolism" and "pyruvate metabolism" were disturbed significantly by R-triticonazole; "phenylalanine metabolism" and "taurine-hypotaurine metabolism" were abnormal in the exposure of S-triticonazole. These results suggested that R- and S-triticonazole could affect different metabolic pathways of human hepatocarcinoma cells, and the massively use of inefficient S-triticonazole should be avoided. Our data will help to better understand the enantioselectivity of chiral pesticides and provide a reference for the development of green pesticides.

Inhibitory effects of Serjania erecta on the development of Chrysodeixis includens

The soybean looper, Chrysodeixis includens, is a primary soybean pest that reduces crop productivity. This work examined control of C. includens populations with methanolic extract of Serjania erecta, a native Cerrado plant, while minimizing risks to pollinators, natural enemies and the environment. Serjania erecta specimens were collected, identified, and subjected to methanol extraction. Bioassays were performed using newly hatched and second-instar caterpillars and different extract concentrations on the diet surface to obtain IC₅₀ values. Two replicates, containing 10 caterpillars, were established in triplicate. The IC₅₀ values were 4.15 and 6.24 mg of extract mL⁻¹ for first-instar and second-instar caterpillars, respectively. These growth inhibition results informed the extract concentrations assessed in subsequent development inhibition assays, in which the pupal weight was higher under the control than under the treatments. Extract treatments increased the duration of the larval, pupal and total development. The potential of different concentrations of S. erecta extract to inhibit the enzymes carboxylesterases was also evaluated. Carboxylesterases activity decreased by 41.96 and 43.43% at 7.8 and 15.6 μg mL⁻¹ extract, respectively. At 31.3 μg mL⁻¹ extract, enzymatic activity was not detected. Overall, S. erecta leaf methanolic extract showed inhibitory potential against carboxylesterases.