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Study on the Metabolism of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea (<em>Camellia Sinensis </em>L.) Leaves

A platform for studying insecticide metabolism using in vitro tissues of tea plant was developed. Leaves from sterile tea plantlets were induced to form ...

source-route-pyrrolizidine-alkaloid-contamination-tea

Source and Route of Pyrrolizidine Alkaloid Contamination in Tea Samples

Toxic pyrrolizidine alkaloids (PAs) are found in tea samples, which pose a threat to human health. However, the source and route of PA contamination in ...

Anhui Province Key Lab of Analysis and Detection for Food Safety

Key Laboratory of Agri-food Safety of Anhui Province

Anhui Agricultural University

Liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) is a primary tool for analysis of low volatility compounds in complex matrices. However, complex matrices, such as different types of tea, complicate analysis through ionization suppression or enhancement. In this study, sample preparation by a refined QuEChERS method combined with a dilution strategy removed almost all matrix effects caused by six types of tea. Tea samples were soaked with water and extracted with acetonitrile, cleaned up with a combination of PVPP (160mg) and GCB (20mg), and dried. Dried extracts were diluted with 20mL acetonitrile/water (15:85, v/v) before analysis by UPLC-MS/MS. The average recoveries of eight neonicotinoid insecticides (dinotefuran, nitenpyram, thiamethoxam, imidacloprid, clothianidin, imidaclothiz, acetamiprid, and thiacloprid) ranged from 66.3 to 108.0% from tea samples spiked at 0.01-0.5mgkg(-1). Relative standard deviations were below 16% for all recovery tests. The limit of quantification ranged from 0.01 to 0.05mgkg(-1). 

Optimized combination of dilution and refined QuEChERS to overcome matrix effects of six types of tea for determination eight neonicotinoid insecticides by ultra performance liquid chromatography-electrospray tandem mass spectrometry.

The uptake, translocation, metabolism, and distribution behavior of glyphosate in nontarget tea plant were investigated. The negative effects appeared to grown tea saplings when the nutrient solution contained glyphosate above 200 mg L. Glyphosate was highest in the roots of the tea plant, where it was also metabolized to aminomethyl phosphonic acid (AMPA). The glyphosate and AMPA in the roots were transported through the xylem or phloem to the stems and leaves. The amount of AMPA in the entire tea plant was less than 6.0% of the amount of glyphosate. The glyphosate level in fresh tea shoots was less than that in mature leaves at each day. These results indicated that free glyphosate in the soil can be continuously absorbed by, metabolized in, and transported from the roots of the tea tree into edible leaves, and therefore, free glyphosate residues in the soil should be controlled to produce teas free of glyphosate.

Uptake, Translocation, Metabolism, and Distribution of Glyphosate in Nontarget Tea Plant (Camellia sinensis L.).

The use of an in vitro cell suspension to study insecticide metabolism is a simpler strategy compared to using intact plants, especially for a difficult matrix such as tea. In this study, a sterile tea leaf callus was inoculated into B liquid media with 2,4-dichlorophenoxyacetic acid (2,4-D, 1.0 mg L) and Kinetin (KT, 0.1 mg L). After 3-4 subcultures (28 days each), a good cell suspension was established. Utilizing these cultures, the metabolic behaviors of six insecticides, including two organophosphates (dimethoate, omethoate) and four neonicotinoids (thiamethoxam, imidacloprid, acetamiprid, and imidaclothiz) were compared. The results showed that thiamethoxam, dimethoate, and omethoate were easily metabolized by tea cells, with degradation ratios after 75 days of 55.3%, 90.4%, and 100%, respectively. Seven metabolites of thiamethoxan and two metabolites of dimethoate were found in treated cell cultures using mass-spectrometry, compared to only two metabolites for thiamethoxam and one for dimethoate in treated intact plants.

Comparison of the Metabolic Behaviors of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea ( Camellia sinensis L.) Leaves.

We describe a novel analytical method for quantification of free amino acids in tea using variable mobile phase pH, elution gradient and column temperature of reversed-phase high-performance liquid chromatography (RP-HPLC). The study of mobile phase pH 5.7 was chosen to simultaneous quantification of 19 free amino acids in tea, while it improved maximum resolution of glutamine, histidine and theanine. Elution gradient was adapted for enhancing the solution of free amino acids, mainly because of adjustment of mobile phase A and B. The column temperature of 40 °C was conducive to separate free amino acids in tea. The limit of detection (LOD) and limit of quantitation (LOQ) of this method were in the range of 0.097-0.228 nmol/mL and 0.323-0.761 nmol/mL, respectively. The relative standard deviation of intraday and interday ranged in 0.099-1.909% and 3.231-7.025%, respectively, indicating that the method was reproducible and precise, while recovery ranged between 81.06-112.78%, showing that the method had an acceptable accuracy. This method was applied for the quantification of free amino acids in six types of tea. Multivariate analysis identified serine, glutamine, theanine and leucine as the most influencing factor for classify among analyzed sample.

Determination of free amino acids in tea by a novel method of reversed-phase high performance liquid chromatography applying 6-Aminoquinolyl--Hydroxysuccinimidyl carbamate reagent.

Thiamethoxam (TMX) has already been proven to have a physiological effect in plant tissue or cell expect for the insecticidal activity. In our previous study, TMX was verified to be metabolized by tea cells in either a suspension culture or tea plant into several metabolites. Here, tea cell suspension cultures were treated for 45 days to investigate the metabolite effects in both the tea cells and the culture supernatants by nontargeted metabolomics. Using multivariate analysis (PCA and OPLS-DA), all treatment and control groups could be clearly separated. Inside the cells, 113 metabolites were found to be up-regulated while 122 were down-regulated, when compared with untreated cells. In the culture supernatant, there were 128 up-regulated and 35 down-regulated metabolites, compared to untreated cultures. KEGG searches revealed that the alanine, aspartate, and glutamate metabolic pathways were strongly affected by TMX metabolism within the tea cell. Molecular docking models showed that (i) 4-aminobutyrate aminotransferase may be related to the formation of 2-chloro-thiazole-5-carboxylic acid and (ii) 3'(2'),5'-bisphosphate nucleotidase may be able to interact with TMX. This study can help us to understand the interaction mechanism of pesticides with plant cells.

Thiamethoxam Metabolism and Metabolic Effects in Cell Suspension Culture of Tea ( Camellia sinensis L.).

Enantioselective metabolism of chiral pesticide in plants is very important. In vitro system has become an effective means to study the metabolism of pesticides in plants, but the study on the metabolism of chiral pesticides has not been reported. This work compared the enantiomer metabolic behavior of acephate and its metabolite methamidophos between tea cell suspensions and excised tea stem with leaves. (±)-Acephate could be absorbed and transferred well to top leaves by the cut end of excised stem after 24 h. (±)-Methamidophos was derived from the metabolism of (±)-acephate in tea plants at 3-5% in leaves and 2-3% in stems at 216 h. The content of (+)-methamidophos was 1.5 times higher than that of (-)-methamidophos in excised leaves. Though both (±)-acephate and (±)-methamidophos could be metabolized well by cell suspension, (±)-acephate and (±)-methamidophos was non-enantioselectively metabolized in cell suspension. It was shown that using the excised tea stem with leaves for chiral pesticide metabolism studies was much closer to intact plant than cell suspensions. This result also established an effective and easily available in vitro metabolic model for the study of enantioselective metabolism of chiral contaminants from environment.

Enantiomer metabolism of acephate and its metabolite methamidophos in in vitro tea (Camellia sinensis L.) systems: Comparison between cell suspensions and excised tissues.

ArticleTotal : 2	Year
Publication title	2019
Publication title	2022

Article	Year
Optimized combination of dilution and refined QuEChERS to overcome matrix effects of six types of tea for determination eight neonicotinoid insecticides by ultra performance liquid chromatog... Food chemistry\| PubMed ID: 27211616	2016
Uptake, Translocation, Metabolism, and Distribution of Glyphosate in Nontarget Tea Plant (Camellia sinensis L.). Journal of agricultural and food chemistry\| PubMed ID: 28795804	2017
Comparison of the Metabolic Behaviors of Six Systemic Insecticides in a Newly Established Cell Suspension Culture Derived from Tea ( Camellia sinensis L.) Leaves. Journal of agricultural and food chemistry\| PubMed ID: 30074784	2018
Determination of free amino acids in tea by a novel method of reversed-phase high performance liquid chromatography applying 6-Aminoquinolyl--Hydroxysuccinimidyl carbamate reagent. Journal of food science and technology\| PubMed ID: 30228426	2018
Thiamethoxam Metabolism and Metabolic Effects in Cell Suspension Culture of Tea ( Camellia sinensis L.). Journal of agricultural and food chemistry\| PubMed ID: 31180663	2019
Enantiomer metabolism of acephate and its metabolite methamidophos in in vitro tea (Camellia sinensis L.) systems: Comparison between cell suspensions and excised tissues. The Science of the total environment\| PubMed ID: 34626633	2022

Weiting Jiao

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