In vitro oxidation promoted by chlorpyrifos residues on myosin and chicken breast proteins

Effect of tannic acid binding on the thermal degradation behavior and product toxicity of boscalid

The effect of tannic acid (TA) binding on the thermal degradation of boscalid was studied in this work. The results revealed that TA binding has a significant impact on boscalid degradation. The degradation rate constant of bound boscalid was reduced, and its corresponding half-life was significantly prolonged compared to the free state. Four identical degradation products were detected in both states through UHPLC-Q-TOF-MS, indicating that degradation products were not affected by TA binding. Based on DFT and MS analysis, the degradation pathways of boscalid included hydroxyl substitution of chlorine atoms and cleavage of CN and CC bonds. The toxicity of B2 and B3 exceeded that of boscalid. In summary, the binding of TA and boscalid significantly affected the thermal degradation rate of boscalid while preserving the types of degradation products. This study contributed to a fundamental understanding of the degradation process of bound pesticide residues in complex food matrices.

Simultaneous quantitative determination of residues of abamectin, ivermectin, albendazole and its three metabolites in beef and chicken by HPLC-PDA

Antimicrobial drugs are frequently used in a combination or shuttle way to cope with coinfection of bacteria or parasites and prevent drug resistance, thus the accurate quantification of multiple drug residues in animal-derived foods is crucial to ensure food safety. Here, a simple and efficient high-performance liquid chromatography-photodiode array (HPLC-PDA) method was established for the simultaneous quantitative screening of six common residues of antiparasitic drugs, including abamectin (ABM), ivermectin (IVM), albendazole (ABZ) and the three metabolites of ABZ in beef and chicken. The LODs and LOQs for six target compounds in beef and chicken are determined to be 3.2 to 12.5 µg/kg and 9.0 to 30.0 µg/kg, respectively. The calibration curves show good linearity (R² ≥ 0.9990) between the peak area and concentration. The recoveries from the fortified blank samples are all above 85.10%. Finally, the applicability of the HPLC-PDA method is successfully demonstrated by the real sample analysis.

Effect of Thermal Processing on the Conformational and Digestive Properties of Myosin

Heat treatment affects the structural properties of meat proteins, which in turn leads to changes in their sensitivity to digestive enzymes, further affecting the nutritional value of meat and meat products. The mechanism of changes in the structure and digestive properties of myosin under different heating conditions were studied. An increase in heating temperature led to the exposure of internal groups to a polar environment, but to a decrease in the sturdy α-helix structure of myosin (p < 0.05). The results of tryptophan fluorescence verified that the tertiary structure of the protein seemed to be unfolded at 70 °C. Higher protein denaturation after overheating, as proven by the sulfhydryl contents and turbidity, caused irregular aggregate generation. The excessive heating mode of treatment at 100 °C for 30 min caused myosin to exhibit a lower degree of pepsin digestion, which increased the Michaelis constant (Km value) of pepsin during the digestion, but induced the production of new peptides with longer peptide sequences. This study elucidates the effects of cooking temperature on the conformation of myosin and the change in digestibility of pepsin treatment during heating.

Characterization of the interaction between boscalid and tannic acid and its effect on the antioxidant properties of tannic acid

The binding of pesticide residues and fruit components may have a profound impact on pesticide dissipation and the functional characteristics of the corresponding components. Therefore, the interaction between boscalid and tannic acid (TA, a representative phenolic in fruit) was systematically investigated using spectroscopic, thermodynamic, and computational chemistry methods. A separable system was designed to obtain the boscalid-TA complex. Fourier transform infrared and ¹ H-NMR spectroscopies indicated the formation of hydrogen bonds in the complex. Isothermal titration calorimetry showed that the complex bound spontaneously through hydrophobic interactions (ΔG < 0, ΔH > 0, ΔS > 0), with a binding constant of 6.0 × 10⁵  M^-1 at 298 K. The molecular docking results further confirmed the formation of hydrogen bonds and hydrophobic interactions in the complex at the molecular level, with a binding energy of -8.43 kcal mol^-1 . In addition, the binding of boscalid to TA significantly decreased the antioxidant activity of TA. The binding of boscalid residue to TA was characterized at the molecular level, which significantly reduced the in vitro antioxidant properties of TA. PRACTICAL APPLICATION: This study provides a reference for the molecular mechanisms of the interaction between pesticide residues and food matrices, as well as a basis for regulating bound-state pesticide residues in food.

The growing concern of chlorpyrifos exposures on human and environmental health

Chlorpyrifos (CP) and its highly electrophilic intermediates are principal toxic metabolites. The active form of CP i.e. chlorpyrifos oxon (CP-oxon) is responsible for both the insecticidal activity and is also of greater risk when present in the atmosphere. Thus, the combined effects of both CP, CP-oxan, and other metabolites enhance our understanding of the safety and risk of the insecticide CP. They cause major toxicities such as AChE inhibition, oxidative stress, and endocrine disruption. Further, it can have adverse hematological, musculoskeletal, renal, ocular, and dermal effects. Excessive use of this compound results in poisoning and potentially kills a non-target species upon exposure including humans. Several examples of reactive metabolites toxicities on plants, aquatic life, and soil are presented herein. The review covers the general overview on reactive metabolites of CP, chemistry and their mechanism through toxic effects on humans as well as on the environment. Considerable progress has been made in the replacement or alternative to CP. The different strategies including antidote mechanisms for the prevention and treatment of CP poisoning are discussed in this review. The approach analyses also the active metabolites for the pesticide activity and thus it becomes more important to know the pesticide and toxicity dose of CP as much as possible.

Using Transcriptomics and Metabolomics to Understand Species Differences in Sensitivity to Chlorpyrifos in Japanese Quail and Double-Crested Cormorant Embryos

Modern 21st-century toxicity testing makes use of omics technologies to address critical questions in toxicology and chemical management. Of interest are questions relating to chemical mechanisms of toxicity, differences in species sensitivity, and translation of molecular effects to observable apical endpoints. Our study addressed these questions by comparing apical outcomes and multiple omics responses in early-life stage exposure studies with Japanese quail (Coturnix japonica) and double-crested cormorant (Phalacrocorax auritus), representing a model and ecological species, respectively. Specifically, we investigated the dose-dependent response of apical outcomes as well as transcriptomics and metabolomics in the liver of each species exposed to chlorpyrifos, a widely used organophosphate pesticide. Our results revealed a clear pattern of dose-dependent disruption of gene expression and metabolic profiles in Japanese quail but not double-crested cormorant at similar chlorpyrifos exposure concentrations. The difference in sensitivity between species was likely due to higher metabolic transformation of chlorpyrifos in Japanese quail compared to double-crested cormorant. The most impacted biological pathways after chlorpyrifos exposure in Japanese quail included hepatic metabolism, oxidative stress, endocrine disruption (steroid and nonsteroid hormones), and metabolic disease (lipid and fatty acid metabolism). Importantly, we show consistent responses across biological scales, suggesting that significant disruption at the level of gene expression and metabolite profiles leads to observable apical responses at the organism level. Our study demonstrates the utility of evaluating effects at multiple biological levels of organization to understand how modern toxicity testing relates to outcomes of regulatory relevance, while also highlighting important, yet poorly understood, species differences in sensitivity to chemical exposure. Environ Toxicol Chem 2021;40:3019-3033. © 2021 SETAC.

Residues of tetracyclines and β-lactams antibiotics induce carbonylation of chicken breast

Background: Worldwide, chicken meat is widely consumed due to its low cost, high nutritional value and non-interference with religious or cultural beliefs. However, during animal husbandry chickens are exposed to many chemical substances, including tetracyclines and β-lactams, which are used to prevent and cure several infections. Some residues of these compounds may bioaccumulate and be present in chicken meat after slaughtering, promoting oxidative reactions. Methods: In order to evaluate in vitro carbonylation induced by tetracyclines and β-lactams residues, a proteomic approach was used. For this, chicken muscle was individually contaminated with tetracyclines (tetracycline, chlortetracycline, oxytetracycline, and doxycycline) and β-lactams (ampicillin, benzathine penicillin, dicloxacillin and oxacillin) at 0.5, 1.0 and 1.5 times their maximum residue level (MRL). Then, sarcoplasmic, myofibrillar and insoluble proteins were extracted and their content were measured using the Bradford method. Protein carbonylation was measured using the 2,4-Dinitrophenylhydrazine alkaline method. Results: Residues of tetracyclines and β-lactams induced in vitro carbonylation on sarcoplasmic, myofibrillar and insoluble proteins even at 0.5MRL concentrations ( p<0.05). When comparing the carbonylation induced by both antibiotics no differences were found ( p>0.05). Variables such as the partition coefficient (log P) and the concentration of these antibiotics showed a high correlation with the oxidative capacity of tetracyclines and β-lactams on chicken breast proteins. Conclusions: This study shows that the presence of tetracyclines and β-lactams residues at MRLs concentrations promotes in vitro carbonylation on chicken breast proteins. Our results provide important insights about the impact of antibiotics on the integrity of meat proteins intended for human consumption.

Label-free proteomic analysis revealed the mechanisms of protein oxidation induced by hydroxyl radicals in whiteleg shrimp (Litopenaeus vannamei) muscle

The oxidative effects of hydroxyl radicals derived from a FeCl₃/ascorbic acid/H₂O₂ system on the stability of muscle proteins in peeled shrimp (Litopenaeus vannamei) were investigated. Physicochemical analysis indicated negative effects on the color (a* value), springiness, and pH of shrimp muscle, which appeared to be significantly exacerbated by higher concentrations of generated hydroxyl radicals when compared with the control. The microstructural results confirmed that a radical attack induced the incompact structure and disintegrated myofibers, thereby leading to weakened connective tissues and decreased stability of muscle proteins. Furthermore, label-free proteomic analysis revealed several differentially abundant proteins (DAPs) (i.e., ribosomal protein subunits, putative cytoskeleton proteins, and ion-binding proteins), which were detected and identified in oxidation-treated shrimp when compared with the control. The gene ontology (GO) and eukaryotic clusters of orthologous group (KOG) analyses further confirmed that the active hydroxyl radicals attacked vulnerable amino acids, modified peptide chains, and/or protein structures and/or conformations, which were responsible for a significant decrease in the muscle texture and stability of proteins in oxidation-treated shrimp. This study provides novel insight into the molecular mechanisms of muscle protein changes during oxidation development.

Fluoroquinolone antibiotics and organophosphate pesticides induce carbonylation on Eisenia fetida muscle proteins

Protein carbonylation is an irreversible oxidative modification that has been associated with a decrease in the quality and nutritional value of products of animal origin. Generally, the carbonylation is attributed to processes of slaughter, processing, and cold storage of products. However, in vitro studies have shown that fluoroquinolone and organophosphate pesticides residues at their maximum residue limits (MRL) can promote carbonylation of animal proteins. Though, this effect on in vivo conditions has not yet been evaluated. Thus, Eisenia fetida was chosen as a model to assay their oxidant effect. For this, adult earthworms were exposed to artificial soil contaminated with ciprofloxacin, danofloxacin, fenthion, and diazinon at three concentrations (0.5, 1.0, and 1.5 MRL) for 28 days. Then, these were purged and sacrificed to obtain the muscle region between the anus and preclitellum. The muscle samples were cold macerated to obtain muscle proteins, which were used for protein quantification, determination of carbonyl levels, and carbonyl protein profiles employing Bradford, Dot-blot, and Western blot assays, respectively. The results showed that at each concentration assayed, all pollutants induced significant carbonylation respect to control (p < 0.05). Additionally, mass spectrometry-based analysis (MALDI-TOF/TOF) identified actin as the protein most susceptible to carbonylation promoted by these substances. Therefore, these findings show for the first time the oxidant power of fluoroquinolones and organophosphates pesticides at MRLs concentrations on muscle proteins under in vivo conditions. Fact causes concern due to the homology of muscle proteins in eukaryotes, which allow to hypothesize that this effect could also be experienced by proteins from food-producing animals in the same way that observed in in vitro studies.