Aerobic dissipation of the novel cyanoacrylate fungicide phenamacril in soil and sludge incubations

Fluorescent and Colorimetric Dual-Readout Immunochromatographic Assay for the Detection of Phenamacril Residues in Agricultural Products

The fungicide phenamacril has been employed to manage Fusarium and mycotoxins in crops, leading to persistent residues in the environment and plants. Detecting phenamacril is pivotal for ensuring environmental and food safety. In this study, haptens and artificial antigens were synthesized to produce antiphenamacril monoclonal antibodies (mAbs). Additionally, gold nanoparticles coated with a polydopamine shell were synthesized and conjugated with mAbs, inducing fluorescence quenching in quantum dots. Moreover, a dual-readout immunochromatographic assay that combines the positive signal from fluorescence with the negative signal from colorimetry was developed to enable sensitive and precise detection of phenamacril within 10 min, achieving detection limits of 5 ng/mL. The method's reliability was affirmed by using spiked wheat flour samples, achieving a limit of quantitation of 0.05 mg/kg. This analytical platform demonstrates high sensitivity, outstanding accuracy, and robust tolerance to matrix effects, making it suitable for the rapid, onsite, quantitative screening of phenamacril residues.

Discovery of benzopyridone cyanoacetates as new type of potential broad-spectrum antibacterial candidates

Unique benzopyridone cyanoacetates (BCs) as new type of promising broad-spectrum antibacterial candidates were discovered with large potential to combat the lethal multidrug-resistant bacterial infections. Many prepared BCs showed broad antibacterial spectrum with low MIC values against the tested strains. Some highly active BCs exhibited rapid sterilization capacity, low resistant trend and good predictive pharmacokinetic properties. Furthermore, the highly active sodium BCs (NaBCs) displayed low hemolysis and cytotoxicity, and especially octyl NaBC 5g also showed in vivo potent anti-infective potential and appreciable pharmacokinetic profiles. A series of preliminary mechanistic explorations indicated that these active BCs could effectively eliminate bacterial biofilm and destroy membrane integrity, thus resulting in the leakage of bacterial cytoplasm. Moreover, their unique structures might further bind to intracellular DNA, DNA gyrase and topoisomerase IV through various direct noncovalent interactions to hinder bacterial reproduction. Meanwhile, the active BCs also induced bacterial oxidative stress and metabolic disturbance, thereby accelerating bacterial apoptosis. These results provided a bright hope for benzopyridone cyanoacetates as potential novel multitargeting broad-spectrum antibacterial candidates to conquer drug resistance.

Effect of novel botanical synergist on the effectiveness and residue behavior of prothioconazole in wheat field

Fusarium head blight (FHB) is a critical fungal disease causes serious grain yield losses and mycotoxin contaminations. Currently, utilization of chemical fungicides is the main control method which has led to serious resistance. Development of novel synergist is an important strategy to reduce the usage of chemical fungicides and postpone the development of resistance, while natural components are interesting resources. In this study, the synergistic effect of Taxodium 'zhongshansha' essential oil (TZEO) was determined and the best synergistic ratio (SR) of 3.96 in laboratory which was observed when the weight ratio of TZEO and prothioconazole was 1 : 1 with the corresponding EC50 (half maximal effective concentration) value of Fusarium graminearum was 0.280 mg L-1. Subsequently, an increase of 6.31% on the control effect to FHB index in field test was observed when compared to the treatment with prothioconazole alone, though there was no significant difference between these treatments. Furthermore, we established an effective method to detect the mycotoxin contaminations in wheat grain with the limits of quantifications (LOQs) value of 5 µg kg-1 (DON, ZEN, 3-DON, and 15-DON) and 1 µg kg-1 (OTA) and the contents were less to the maximum residue limit (MRL) values. It was also shown that the application of 20% TZEO EW led to a 20% reduction in the use of prothioconazole, which was calculated based on the control effect values of 86.41% and 90.20% between the treatments of 30% prothioconazole OD (225 g a.i ha-1, recommend dosage) and 30% prothioconazole OD (180 g a.i ha-1) + 20% TZEO EW (225 mL ha-1), significantly. The initial residue of prothioconazole and prothioconazole-desthio was increased in the treatment with TZEO, which may play an important role in the synergistic effect on FHB. Moreover, none of the treatments posed a prothioconazole residue risk in the wheat grain and the environment. In addition, the essential oil has no any negative influence on wheat growth, which was revealed by a study of the chlorophyll content. These results provide an important botanical synergist for use with prothioconazole to control Fusarium head blight, and in-depth study to the synergistic mechanism of this oil is necessary in our future research.

Construction and characterization of ethyl cellulose-based nano-delivery system for phenamacril

Fungicide-resistant Fusarium has become a threaten to wheat production. Novel fungicide formulations can improve the efficacy of active ingredient and minimize the emergence of resistance. Encapsulation of fungicides in biodegradable carriers, especially, in polysaccharide, is a feasible approach to develop environment-friendly and efficient formulation. This study focused on the synthesis of ethyl cellulose-based phenamacril nano-delivery system by combining emulsion-solvent evaporation and high-pressure homogenization technology to improve the control of fusarium head blight in wheat. Emulsifier 125 and Tersperse 2500 were screened from eleven commonly used surfactants. Emulsifier 125 and Tersperse 2500 in a ratio of 2:1 and phenamacril nanocapsules with the mean particle size of 152.5 ± 1.3 nm were prepared. These showed excellent storage stability and wettability on crop leaves. A bioassay comparing the nanocapsules with a commercial preparation against Fusarium graminearum showed significantly improved biological activity. This formulation could be used to effectively not only to control fusarium head blight but also delay the occurrence of resistance.

Insight into the uptake, accumulation, and metabolism of the fungicide phenamacril in lettuce (Lactuca sativa L.) and radish (Raphanus sativus L.)

The fungal species Fusarium can cause devastating disease in agricultural crops. Phenamacril is an extremely specific cyanoacrylate fungicide and a strobilurine analog that has excellent efficacy against Fusarium. To date, information on the mechanisms involved in the uptake, accumulation, and metabolism of phenamacril in plants is scarce. In this study, lettuce and radish were chosen as model plants for a comparative analysis of the absorption, accumulation, and metabolic characteristics of phenamacril from a polluted environment. We determined the total amount of phenamacril in the plant-water system by measuring the concentrations in the solution and plant tissues at frequent intervals over the exposure period. Phenamacril was readily taken up by the plant roots with average root concentration factor ranges of 60.8-172.7 and 16.4-26.9 mL/g for lettuce and radish, respectively. However, it showed limited root-to-shoot translocation. The lettuce roots had a 2.8-12.4-fold higher phenamacril content than the shoots; whereas the radish plants demonstrated the opposite, with the shoots having 1.5 to 10.0 times more phenamacril than the roots. By the end of the exposure period, the mass losses from the plant-water systems reached 72.0% and 66.3% for phenamacril in lettuce and radish, respectively, suggesting evidence of phenamacril biotransformation. Further analysis confirmed that phenamacril was metabolized via hydroxylation, hydrolysis of esters, demethylation, and desaturation reactions, and formed multiple transformation products. This study furthers our understanding of the fate of phenamacril when it passes from the environment to plants and provides an important reference for its scientific use and risk assessment.

Ameliorative effects of biochar on persistency, dissipation, and toxicity of atrazine in three contrasting soils

The presence of atrazine a persistent herbicide in soil poses a serious threat to the ecosystem. The biochar amendment in soil altered the fate of this herbicide by modifying the soil properties. The present study examines the dissipation and toxicity of atrazine in three contrasting soils (silty clay, sandy loam, and sandy clay) without and with biochar amendment (4%). The experiment was performed for 150 days with three application rates of atrazine (4, 8, and 10 mg kg^-1). The speciation and degradation of atrazine, metabolite content, microbial biomass, and enzymatic activities were evaluated in all treatments. Three kinetic models and soil enzyme index were calculated to scrutinize the degradation of atrazine and its toxicity on soil biota, respectively. The goodness of fit statistical indices suggested that the first-order double exponential decay (FODE) model best described the degradation of atrazine in silty clay soil. However, a single first order with plateau (SFOP) was best fitted for atrazine degradation in sandy loam and sandy clay soils. The half-life of atrazine was higher in sandy clay soil (27-106 day^-1) than silty clay (28-77 day^-1) and sandy loam soil (27-83 day^-1). The variations in the dissipation kinetics and half-life of the atrazine in three soil were associated with atrazine partitioning, availability of mineral content (silica, aluminum, and iron), and soil microbial biomass carbon. Biochar amendment significantly reduced the plateau in the kinetic curve and also reduced the atrazine toxicity on soil microbiota. Overall, biochar was more effective in sandy clay soil for the restoration of soil microbial activities under atrazine stress due to modulation in the pH and more improved soil quality.

Effect of application method and formulation on prothioconazole residue behavior and mycotoxin contamination in wheat

In this study, efficient and sensitive analytical methods based on liquid chromatography-tandem mass spectrometry were established to evaluate the degradation behavior of prothioconazole and prothioconazole-desthio along with mycotoxin contamination in wheat samples. The mean recoveries of prothioconazole and prothioconazole-desthio ranged from 76.05% to 96.17% with intraday relative standard deviations (RSDs) of 0.84%-14.38%. Mean recoveries of the five mycotoxins were 85.82%-103.24% with RSDs of 1.82%-7.03%. The residue and degradation behavior of prothioconazole was studied in wheat plant and grain under field conditions with different spraying equipment and prothioconazole formulations. Both application method and formulation affected prothioconazole degradation, and the content of all mycotoxin was lower than the national standards. The proposed analytic methods can be used to systematically evaluate prothioconazole and prothioconazole-desthio along with mycotoxin contamination in food. These results suggest that prothioconazole is safe for the control Fusarium head blight in wheat.