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[学术文献 ] Dissipation dynamics of methomyl, phoxim, and pymetrozine during mulberry (Morus alba L.) leaves harvest, tea processing and brewing 进入全文
Food Chemistry 期刊
Mulberry leaf tea is known for its health benefits; however, concerns remain about pesticide residues during harvest, processing, and brewing. The dissipation dynamics of methomyl, phoxim, and pymetrozine were systematically investigated in this study. In fresh leaves, their half-lives ranged from 1.1 to 2.3 days, with dissipation rates of 64.6–87.8 % within three days. During tea processing, dissipation rates in black and green tea ranged from 46.3 % to 78.9 %, influenced by the initial pesticide levels and processing conditions. The dissipation of pesticides was significantly influenced by drying and spreading/withering. During brewing, pesticide leaching was closely related to water solubility, with 33.8–76.9 % of methomyl and pymetrozine transferring to the infusion, compared to just 0.32–3.2 % for the less water-soluble phoxim. Overall, at least 85 % of the pesticides dissipated across harvest, processing, and brewing, suggesting negligible health risks based on risk quotient assessment.
[学术文献 ] Residue analysis and risk assessment of cyflumetofen and its three metabolites from fresh tea leaf to tea infusion through purification with new nano adsorbents and determination by ultra-performance liquid chromatography-tandem mass spectrometry 进入全文
Microchemical Journal 期刊
A simultaneous residue analysis method for cyflumetofen and its three metabolites (B-1, B-3, and AB-1) in fresh tea leaves, green tea, black tea, green tea infusion and black tea infusion was developed. Samples were extracted with acetonitrile containing 1 % of formic acid, followed by purification using multi-walled carbon nanotubes (MWCNT) and nano-ZrO2 absorbents in conjunction with low-temperature clean (LTC). The samples were then analyzed by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The calibration curves for cyflumetofen and its metabolites, ranging from 0.005 to 2.0 mg/L (excluding B-1, which is from 0.01 to 2.0 mg/L), demonstrated satisfactory correlation coefficients (R2) of at least 0.9931 across various tea matrix-matched conditions. The average recoveries for cyflumetofen and its three metabolites in different tea matrixes ranged from 71.9 % to 116.9 %, with relative standard deviations (RSDs) below 15.1 %. The limits of quantification (LOQs) were set at 0.005 mg/kg for fresh tea leaves, black tea, and green tea, and 0.5 µg/L for black and green tea infusion. For B-1, the LOQs were set at 0.01 mg/kg for black and green tea, and 1.0 µg/L for black and green tea infusion. After applying a 20 % cyflumetofen suspension concentrate to a tea plant field, real fresh tea leaf samples were found to contain cyflumetofen and its three metabolites B-1, B-3, and AB-1. The half-life (t1/2) of cyflumetofen in fresh tea leaves was found to be 1.18 days. During the tea processing, various processing steps had distinct impacts on compound residues, especially under high-temperature conditions. The total processing factors (TPFs) for cyflumetofen in green tea and black tea ranged from 0.75 to 1.16 and 1.31 to 2.78, respectively. The leaching rates (LRs) of cyflumetofen from tea to tea infusion were 2.6 % for green tea and 2.4 % for black tea. Based on risk assessment, the total dietary risk quotients for both cyflumetofen and B-1 were significantly below 100 %.
[学术文献 ] Neonicotinoid Insecticides and Their Characteristic Metabolites may Induce High Fasting Blood Glucose and Obesity in Human 进入全文
Exposure and Health 期刊
In this study, the concentrations of six NEOs and their five metabolites were measured in the blood samples collected from the normal (n = 130) and obesity (n = 130) cohorts in South China. An evaluation was undertaken to examine the associations between the levels of target analytes and either fasting blood glucose (FBG) or the condition of being overweight. Results showed that the NEOs and their metabolites were frequently detected (63–100%) in both cohorts, with median levels of 0.01–4.32 ng/mL. Discernible gender-related disparities were noted within the blood samples, manifesting as elevated concentrations of the majority of NEOs and their metabolites in females compared to males. In addition, there were positive correlations between the concentrations of IMIeq (imidacloprid equivalent, calculated using the relative potency factors of NEOs and their metabolites) and 1-methyl-3-(tetrahydro-3-furylmethyl) urea (UF, a metabolite of dinotefuran) with FBG levels (3.28 ng/mL vs. 4.32 ng/mL for UF, and 34.6 ng/mL vs. 40.6 ng/mL for IMIeq). Moreover, significant associations were found between UF [odds ratio 1.78, 95% confidence interval (CI) 0.86–4.66, p < 0.01] and IMIeq (odds ratio 1.66, 95% CI 0.94–3.56, p < 0.01) concentrations and being overweight. Our findings indicated that human exposure to NEOs and their metabolites may induce high FBG and obesity. This study documented the profile of NEOs and their metabolites in the blood samples from the normal and obesity cohorts in South China for the first time.
[学术文献 ] Metabolic mechanism, responses, and functions of genes HDH1, HDH3, and GST1 of tea ( Camellia sinensis L.) to the insecticide thiamethoxam 进入全文
Journal of Hazardous Materials 期刊
Misuse of insecticides such as thiamethoxam (TMX) not only affects the quality of tea but also leaves residues in tea. Therefore, exploring the metabolic mechanisms of TMX in tea plants can evaluate effects of pesticides on the environment and human health. Here, effects of TMX on tea plants were studied. Malondialdehyde (MDA) content reached a maximum of 12.59 nmol/g fresh weight (FW) on 1st d under X (the recommended dose: 0.015 kg a.i./ha) of TMX. Under 2 X (0.03 kg a.i./ha), the catalase, glutathione S-transferase and superoxide dismutase activity were increased by 45.0 %, 55.5 %, and 49.7 % at 7 d respectively. Metabolomic and transcriptomic analyses revealed that TMX significantly affected amino acid metabolism, flavonoid biosynthesis and glutathione metabolism, and induced the expression of 3-hydroxyisobutyric acid dehydrogenase genes (CsHDH1 and CsHDH3) and glutathione S-transferase gene (CsGST1). The three genes were transiently expressed in Nicotiana benthamiana for the first time to verify the function of TMX degradation, with the degradation rate of 59.2 %-85.3 % at X. This study elucidated the response of tea plants to abiotic stress on the molecular-scale perspective, and the molecular approaches could serve as a model for the study on pesticide metabolism in plants.
[学术文献 ] Evaluating the Effects of Flavonoids on Insects: Implications for Managing Pests Without Harming Beneficials 进入全文
Insects 期刊
Flavonoids are secondary metabolites that deter attacks from some plant-feeding insects. The hypothesis that flavonoids and flavonoid glycosides can be utilized to manage pest insects without negatively affecting beneficial insects was evaluated. Scientific literature databases were examined. Flavonoids were harmful to most true bugs and true flies but harmless to bees. Flavonoid glycosides showed a tendency to harm true bugs and true flies but not harm sawflies. Flavonoids and flavonoid glycosides caused a mixture of harmful and harmless outcomes to plant-feeding beetles. Flavonoid glycosides were harmless to butterflies. In conclusion, these compounds have moderate potential as attractants, stimulants, repellents, deterrents, and less-toxic insecticides against some pests, especially true bugs and true flies, without harming beneficials.
[学术文献 ] Plant response to touch vs. insect feeding vibrations 进入全文
Arthropod-Plant Interactions 期刊
Plants experience a wide variety of mechanical stimuli in their environment, some of which indicate the presence of herbivory. Insect feeding vibrations elicit direct and primed increases in levels of defensive compounds. Touch is also a mechanical stimulus arising from rain, wind, and the movement of herbivores and pollinators. In this study, we compared the effect of insect feeding vibrations on flavonoid defenses with two other mechanical stimuli, a silent sham treatment and an active touch treatment. Feeding vibrations caused a direct increase in the concentration of anthocyanins compared to silent sham and active touch, and elicited no priming effects on response to methyl jasmonate. Silent sham caused a priming increase in the concentration of flavonols compared to feeding vibrations and active touch, and there were no direct effects. Although these results provide additional evidence for plant discrimination among mechanical stimuli, we discuss the common intertwining of touch and vibration in what plants experience in natural environments. We propose that touch and vibration are likely perceived by plants as related mechanical stimuli, and encourage broader exploration of this core feature of plant sensory ecology.
