Deciphering the interactions between altertoxins and glutenin based on molecular dynamic simulation: inspiration from detection.

BACKGROUND: Mycotoxin contamination of food has been gaining increasing attention. Hidden mycotoxins that interact with biological macromolecules in food could make the detection of mycotoxins less accurate, potentially leading to the underestimation of the total exposure risk. Interactions of the mycotoxins alternariol (AOH) and alternariol monomethyl ether (AME) with high-molecular glutenin were explored in this study. RESULTS: The recovery rates of AOH and AME (1, 2, and 10 µg kg-1) in three types of grains (rice, corn, and wheat) were relatively low. Molecular dynamics (MD) simulations indicated that AOH and AME bound to glutenin spontaneously. Hydrogen bonds and π-π stacking were the primary interaction forces at the binding sites. Alternariol with one additional hydroxyl group exhibited stronger binding affinity to glutenin than AME when analyzing average local ionization energy. The average interaction energy between AOH and glutenin was -80.68 KJ mol-1, whereas that of AME was -67.11 KJ mol-1. CONCLUSION: This study revealed the mechanisms of the interactions between AOH (or AME) and high-molecular glutenin using MD and molecular docking. This could be useful in the development of effective methods to detect pollution levels. These results could also play an important role in the evaluation of the toxicological properties of bound altertoxins. © 2024 Society of Chemical Industry.

The adsorption-desorption behavior of chlorothalonil in the cuticles of apple and red jujube.

The distribution fate of chlorothalonil (CHT) in the environment (soil and water) and fruits is controlled by the capacity of cuticles to adsorb and desorb CHT, which directly affects the safety of both the environment and fruits. Batch experiments were conducted to reveal the adsorption-desorption behaviors of CHT in the cuticles of apple and red jujube. The adsorption kinetics showed that both physisorption and chemisorption occurred during the adsorption process. Furthermore, the isothermal adsorption of CHT in the fruit cuticles followed the Freundlich model. The thermodynamic parameters (ΔG ≤ -26.16 kJ/mol, ΔH ≥ 31.05 kJ/mol, ΔS ≥ 0.20 kJ/(mol K) showed that the whole CHT adsorption process was spontaneous, and the hydrophobic interaction was predominant. The CHT adsorption capacity of the apple cuticle was higher than that of the red jujube cuticle, potentially due to the significantly higher alkanes content of apples than that of red jujubes. An appropriate ionic strength (0.01 moL/L) could induce a higher adsorption capacity. In addition, the desorption kinetics were shown to conform to a Quasi-first-order model, meaning that not all the adsorbed CHT could be easily desorbed. The desorption ratios in apple and red jujube cuticles were 41.38% and 35.64%, respectively. The results of Fourier-transformed infrared spectroscopy and X-ray photoelectron spectroscopy further confirmed that CHT could be adsorbed and retained in the fruit cuticles. Investigating the adsorption-desorption behavior of CHT in the apple and red jujube cuticles allowed to determine the ratio of its final distribution in the fruits and environment, providing a theoretical basis to evaluate the risk of residue pesticide.

Degradation of carbofuran and acetamiprid in wolfberry by dielectric barrier discharge plasma: Kinetics, pathways, toxicity and molecular dynamics simulation.

Carbofuran and acetamiprid pose the highest residual risk among pesticides found in wolfberries. This study aimed to degrade these pesticides in wolfberries using a multi-array dielectric barrier discharge plasma (DBD), evaluate the impact on safety and quality and explore their degradation mechanism. The results showed that DBD treatment achieved 90.6% and 80.9% degradation rates for carbofuran and acetamiprid, respectively, following a first-order kinetic reaction. The 120 s treatment successfully reduced pesticide contamination to levels below maximum residue limits. Treatment up to 180 s did not adversely affect the quality of wolfberries. QTOF/MS identification and degradation pathway analysis revealed that DBD broke down the furan ring and carbamate group of carbofuran, while replacing the chlorine atom and oxidizing the side chain of acetamiprid, leading to degradation. The toxicological evaluation showed that the degradation products were less toxic than undegraded pesticides. Molecular dynamics simulations revealed the reactive oxygen species (ROS) facilitated the degradation of pesticides through dehydrogenation and radical addition reactions. ROS type and dosage significantly affected the breakage of chemical bonds associated with toxicity (C4-O5 and C2-Cl1). These findings deepen insights into the plasma chemical degradation of pesticides.

Interaction between Six Waxy Components in Summer Black Grapes (Vitis vinifera) and Mancozeb and Its Effect on the Residue of Mancozeb.

Mancozeb, an antifungal typically used for the growth of fruits, has the characteristic of non-internal absorption, and has a risk of binding to the waxy components of fruits. This work investigated the interaction of pesticide molecules with the waxy layer on the grape surface and their effects on pesticide residues in grapes. The study observed significant changes in the compositions of the waxy layer on the grape surface after soaking in a mancozeb standard solution. The six substances-oleanolic acid, ursolic acid, lupeol, octacosanol, hexacosanal, and γ-sitosterol-with discernible content differences were chosen for molecular docking. Docking results were further visualized by an independent gradient model based on Hirshfeld partition (IGMH). Hydrogen bonds and van der Waals forces were found between mancozeb and the six waxy components. Moreover, the negative matrix effects caused by the presence or absence of wax for the determination of mancozeb were different through the QuEChERS-HPLC-MS method. Compared with the residue of mancozeb in grapes (5.97 mg/kg), the deposition of mancozeb in grapes after dewaxing was significantly lower (1.12 mg/kg), which further supports that mancozeb may interact with the wax layer compositions. This work not only provides insights into the study of the interaction between pesticides and small molecules but also provides theoretical guidelines for the investigation of the removal of pesticide residues on the surface of fruits.

Facile extraction and determination of organophosphorus pesticides in vegetables via magnetic functionalized covalent organic framework nanocomposites.

Facile enrichment and determination of trace organophosphorus pesticides (OPPs) in foods has been a constantly pursuing goal in food safety field. Herein, Zr4+-immobilized covalent organic frameworks (Fe3O4@COF@Zr4+) have been first constructed and utilized as the powerful adsorbents for magnetic solid-phase extraction (MSPE) of OPPs. Owing to the π-π stacking interaction, hydrogen bonding and Zr4+-phosphate coordination reaction, the composites exhibited excellent selectivity and superior affinity to OPPs. Under optimized conditions, the proposed MSPE method coupled with GC-FPD showed good linearity (R2 ≥ 0.9990) and yielded low limits of detection (0.7-3.0 µg kg-1) for OPPs. Moreover, the developed method was successfully employed for the quantitation of OPPs in spiked vegetable samples and obtained satisfactory recoveries in the range of 87-121% with the relative standard deviations (RSDs) ≤ 8.9%. These results demonstrated that the prepared nanoparticles hold unique advantages for trace OPPs analysis in foodstuffs.

ß-Cyclodextrin-/AuNPs-functionalized covalent organic framework-based magnetic sorbent for solid phase extraction and determination of sulfonamides.

ß-Cyclodextrin-functionalized magnetic covalent organic framework (Fe3O4@COF@Au-ß-CD) was developed as sorbent for magnetic solid phase extraction of trace sulfonamides in meat samples prior to HPLC-MS/MS analysis. The sorbent was synthesized by loading gold nanoparticles onto a Fe3O4@COF surface and then functionalized by thiolated-ß-cyclodextrin immobilization via Au-S bonding formation. The prepared composite material was employed for sulfonamides extraction. The main parameters were optimized to obtain the best extraction efficiency. The experiments of adsorption kinetics were carried out to investigate the adsorption mechanism. Results showed the pseudo-second-order kinetic was better fitted with the adsorption kinetics of sulfonamides. Under optimized conditions, the magnetic solid phase extraction-HPLC method showed good linearity (R2 ≥ 0.9936), and the limits of detection were in the range of 0.8-1.6 µg kg-1. The proposed method was successfully used for quantitation of sulfonamides in real samples. The recoveries ranged from 78.9 to 112.0% with relative standard deviations (RSDs) < 10% (n = 5). The proposed method exhibited great potential for enrichment and determination of sulfonamides in many other food or environment samples. Graphical abstract.

Sulphonate functionalized covalent organic framework-based magnetic sorbent for effective solid phase extraction and determination of fluoroquinolones.

Most of the reported covalent organic frameworks (COFs) are hydrophobic, limiting their adsorption application in sample pretreatment field. In this work, sulphonate functionalized magnetic covalent organic frameworks (COFs) composites were first synthesized by loading gold nanoparticles on Fe3O4@COF(TpBD) surface and then functionalized by sodium 3-mercaptopropanesulphonate immobilization via Au-S bonding formation (denoted as Fe3O4@COF(TpBD)@Au-MPS nanocomposites), which were further utilized as adsorbents for magnetic solid-phase extraction (MSPE) of fluoroquinolones. Compared with Fe3O4@COF(TpBD), the composites exhibited higher affinity to fluoroquinolones. Under optimized conditions, the developed MSPE method coupled with HPLC-MS/MS showed good linearity (R2 ≥0.9989) and yielded low limits of detection (0.1-1.0 µg kg-1) for fluoroquinolones. Moreover, the proposed method was successfully applied to extract fluoroquinolones from spiked meats (pork, chicken and bovine). The satisfactory recoveries were in the range of 82-110.2% with the relative standard deviations (RSDs) lower than 7.7%. These results indicated that the Fe3O4@COF(TpBD)@Au-MPS is a promising magnetic adsorbent for trace fluoroquinolones determination in meat samples. This work not only provided a facile strategy for COF functionalization, but also developed an efficient method for detecting fluoroquinolones in foodstuffs.