Determination of triazine herbicides and their metabolites in multiple medicinal parts of traditional Chinese medicines using streamlined pretreatment and UFLC-ESI-MS/MS

Insights into interaction of triazine herbicides with three kinds of different alkyl groups (simetryne, ametryn and terbutryn) with human serum albumin via multi-spectral analysis

In this study, the interaction of triazine herbicides with three kinds of different alkyl groups (simetryne, ametryn and terbutryn) with human serum albumin (HSA) are investigated through UV-vis, fluorescence, and circular dichroism (CD) spectra. The mechanisms on the fluorescence quenching of HSA initiated by triazine herbicides are obtained using Stern-Volmer, Lineweaver-Burk and Double logarithm equations. The quenching rate constant (Kq), Stern-Volmer quenching constant (Ksv), binding constant (KA), thermodynamic parameters such as enthalpy change (∆H), entropy change (∆S) and Gibbs free energy (∆G) and number of binding site (n) are calculated and compared. The variations in the microenvironment of amino acid residues are studied by synchronous fluorescence spectroscopy. The binding sites and subdomains are identified using warfarin and ibuprofen as site probes. The conformational changes of HSA are measured using CD spectra. The results reveal that the triazine herbicides with different alkyl groups can interact with HSA by static quenching. The combination of the three herbicides and HSA are equally proportional, and the binding processes are spontaneous. Hydrophobic interaction forces play important roles in simetryne-HSA and ametryn-HSA, while the interaction of terbutryn-HSA is Van der Waals forces and hydrogen bonding. Moreover, the three herbicides can bind to HSA at site I (sub-domain IIA) more than site II (subdomain IIIA), and combine with tryptophan (Trp) more easily than tyrosine (Tyr) residues, respectively. By comparison, the order of interaction strength is terbutryn-HSA > ametryn-HSA > simetryne-HSA. Terbutryn can destroy the secondary structure of HSA more than simetryne and ametryn, and the potential toxicity of terbutryn is higher. It is expected that the interactions of triazine herbicides with HSA via multi-spectral analysis can offer some valuable information for studying the toxicity and the harm of triazine herbicides on human health at molecular level in life science.

Toxic effects of detected pyrethroid pesticides on honeybee (Apis mellifera ligustica Spin and Apis cerana cerana Fabricius)

To obtain the presence of environmental contaminants in honeybee and compare the toxicity of the detected pesticides to Apis mellifera ligustica Spin and Apis cerana cerana Fabricius. In this work, 214 honeybee samples were collected to simultaneous monitoring 66 pesticides between 2016 and 2017 in China. A modified QuEChERS extraction method coupled with multi-residue analytical methods by Ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and Gas chromatography-mass spectrum (GC–MS). Among, four pyrethroid pesticides were selected to test and compare the acute oral toxicities of two honeybees. And the survival risk of beta-cypermethrin was analyzed to them. Using this method, 21 compounds were detected, including 3 neonicotinoids, 5 pyrethroids, 5 organophosphorus and 8 others. Importantly, detected frequencies of pyrethroid pesticides were accounted for 53.3%. Among, acute toxicity values (LD₅₀) of four pyrethroid pesticides to the A.m. ligustica were higher than of that the A.c. cerana. When they were exposed to the same concentration of beta-cypermethrin (0.2906 mg/L), the survival rate of the A.m. ligustica (40.0%) was higher than the A.c. cerana (18.9%). Our work is valuable to analyze multiple pesticide residues of honeybees and evaluate the survival risk of two honeybee species, which also provides a basis for the risk assessment.

Selection and colorimetric application of ssDNA aptamers against metamitron based on magnetic bead-SELEX

Metamitron (MTM) is a typical and widely used triazine herbicide in agricultural production. Its moderate toxicity and high residue in the environment have deleterious impacts on human health. The establishment of a rapid and efficient MTM detection method is of great significance. In this study, a magnetic-bead SELEX (systematic evolution of ligands by exponential enrichment) system was developed to select the MTM aptamers with high affinity and specificity. Through 10 rounds of screening, six candidate aptamers with the highest abundance were obtained by high-throughput sequencing. The homology, secondary structure, and affinity analyses were performed. The aptamer named MTM-6 was selected as the optimal aptamer with the dissociation constant (K_d) value of 16 nM. Then, a colorimetric detection method for MTM based on aptamer MTM-6 and the aggregation of gold nanoparticles (AuNPs) induced by NaCl was established with a linear range from 20 to 1000 nM (R = 0.9966) and a limit of detection (LOD) of 4.58 nM. The average recovery rate of MTM in the application of actual aqueous samples ranged from 95.40 to 107.83% with a relative standard deviation (RSD) from 1.11 to 3.48%. With considerable sensitivity and specificity, this colorimetric aptasensor is convenient and efficient, and shows bright application potential in MTM detection in aqueous samples.

Facile synthesis of a novel magnetic covalent organic frameworks for extraction and determination of five fungicides in Chinese herbal medicines

A novel magnetic covalent organic framework was synthesized via one step coating approach with solvothermal reaction employing 2,4,6-tris(4-aminophen-yl)-1,3,5-triazine and 2,4,6-triformylphloroglucinol as two building blocks by covalent bonding. The prepared magnetic covalent organic frameworks were properly characterized by different techniques and employed as adsorbent of magnetic solid phase extraction. An analytical method was developed for simultaneous determination of five fungicides in two Chinese herbal medicine samples via magnetic solid phase extraction coupled to UHPLC-MS/MS analysis. Under optimized magnetic solid phase extraction conditions, the method exhibited satisfactory recoveries (74.0-109.6%) with the relative standard deviations of 0.4-4.6%, low limits of detection (0.003-0.015 μg kg^-1 ), and good linearity (R² > 0.9960). Compared with the traditional extraction method, the proposed method required a lower amount of adsorbent (3 mg) and extraction time (5 min). The adsorbent also had favourable reusability (not less than 8 times). Therefore, the magnetic covalent organic frameworks could be a promising adsorbent for the extraction and quantitation of pesticide residues in Chinese herbal medicines. This article is protected by copyright. All rights reserved.

Occurrence and Removal of Triazine Herbicides during Wastewater Treatment Processes and Their Environmental Impact on Aquatic Life

Wastewater treatment plants (WWTPs) represent a major point source for pesticide residue entry to aquatic environment and may threaten ecosystems and biodiversity in urban area. Triazine herbicides should be paid attention to for their ubiquitous occurrence in the environment and long-term residue. The present study aimed to quantify eleven compounds of triazine herbicides during wastewater treatment processes. The solid phase extraction and gas-chromatography mass spectrometry (GC-MS) determination method were developed to identify the target herbicides with approving sensitivity. The pollution levels, removal rates of eleven triazine herbicides along five different treatment stages in WWTP were investigated. The results showed that three herbicides including atrazine, simetryn and prometryn were detected. Their concentrations in influent were among 28.79 to 104.60 ng/L. Their total removal rates from influent to effluent were 14.92%, 10.79% and 4.41%, respectively indicating that they were difficult to be effectively remove during wastewater treatment. Regarding the negative impact of triazine herbicides discharged from WWTPs on downstream water quality and aquatic life, the environmental risks were assessed by calculating the Environmental Relevance of Pesticides from Wastewater Treatment Plants Index (ERPWI) and water cycle spreading index (WCSI). The risk assessment results denoted the possible high risks for atrazine and simetryn to alage, and simetryn concurrently posed a high risk for the daphnia, while prometryn was at medium risk to alage. Atrazine and simetryn in effluent posed high risk for algae, meanwhile, simetryn had high risk for Daphnia. These results suggested a possible threat to the aquatic environment, rendering in this way the ERPWI method as a useful assessment tool. Further extensive study is needed for atrazine and simetryn in order to better understand their migration mechanism in aquatic environment.

Acceptable risk of fenpropathrin and emamectin benzoate in the minor crop Mugua (Chaenomeles speciosa) after postharvest processing

Production of minor crop varieties often requires intensive pesticide use, which raises serious concerns over food safety and human health. Chaenomeles speciosa (Sweet) Nakai as one of the representative of this kind of crops is therefore used for investigating the residue behavior of fenpropathrin and emamectin benzoate, a synthetic pyrethroid and macrocyclic lactone widely used as an insecticide, respectively, from cultivation to C. speciosa postharvest processing. Results showed that the degradation trends of those selected insecticides in C. speciosa followed first-order kinetics with an average half-life (t_1/2) of 3.7-4.1 days and a dissipation rate of 97% over 14 days. The terminal residues of fenpropathrin and emamectin benzoate at 120 and 3 g a.i./ha were below the U.S Environmental Protection Agency (FAD, 1.00 mg/kg) and European Union (EU, 0.01 mg/kg) maximum residue limits (MRLs) in papaya species, respectively, when measured 14 days after the final application, which suggested that the use of these insecticides was safe for humans. Postharvest processing procedure resulted in a |90% reduction of the insecticides. Moreover, the hazard quotient (HQ) for C. speciosa decoction (with processing factors) indicated an acceptable risk for human consumption. These findings provide the scientific evidence of reasonable application and risk assessment of the selected pesticide residues in C. speciosa.

A combination index and glycoproteomics-based approach revealed synergistic anticancer effects of curcuminoids of turmeric against prostate cancer PC3 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Herbal medicines (HMs) often exert integration effects, including synergistic, additive and antagonistic effects, in such ways that they act on multiple targets and multiple pathways on account of their multiple components. Turmeric, made from the rhizome of Curcuma longa L., is a well-known HM prescribed in the polyherbal formulas for cancer treatment in traditional Chinese medicines (TCMs). However, neither the multiple anticancer compounds of turmeric nor the integration effects of these components are fully known.

AIM OF THE STUDY

This work aims to develop a systematic approach to reveal the integration effect mechanisms of multiple anticancer compounds in turmeric against prostate cancer PC3 cells.

MATERIALS AND METHODS

Combination index and omics technologies were applied to profile the integration effect mechanisms of bioactive compounds in proportions naturally found in turmeric. PC3 cell line (a prostate cancer cell line) fishing and high resolution mass spectrometry were employed to screen and identify the anticancer compounds from turmeric. The combinations which contain different cell-bound compounds in natural proportions were prepared for further evaluation of anti-cancer activity by using cell viability assays, and assessment of cell apoptosis and cell cycle analysis. Combination index analysis was applied to study the integration effects of the anticancer compounds in their natural proportions. Finally, quantitative glycoproteomics/proteomics and Western blot were implemented to reveal the potential synergistic effect mechanisms of the anticancer compounds based on their natural proportions in turmeric.

RESULTS

Three curcuminoids (curcumin, CUR; demethoxycurcumin, DMC; bisdemethoxycurcumin, BDMC) in turmeric were discovered and shown to possess significant synergistic anticancer activities. Combination index analysis revealed an additive effect of CUR combined with DMC or BDMC and a slight synergistic effect of DMC combined with BDMC in natural proportions in turmeric, while a combination of all three curcuminoids (CUR, DMC and BDMC) at a ratio of 1:1:1 yielded superior synergistic effects. Interestingly, the presence of BDMC and DMC are essential for synergistic effect. Glycoproteomics and proteomics demonstrated that different curcuminoids regulate various protein pathways, such as ribosome, glycolysis/gluconeogenesis, biosynthesis of amino acids, and combination of CUR + DMC + BDMC showed the most powerful effects on down-regulation of protein expression.

CONCLUSIONS

Our analytical approach provides a systematic understanding of the holistic activity and integration effects of the anti-cancer compounds in turmeric and three curcuminoids of turmeric showed a synergistic effect on PC3 cells.

Improved photocatalyst: Elimination of triazine herbicides by novel phosphorus and boron co-doping graphite carbon nitride

A non-metallic and low-cost novel phosphorus and boron co-doping graphite carbon nitride (PB-g-C₃N₄) photocatalyst was prepared by a facile thermal copolymerization of urea with B₂O₃ and (NH₄)₂·HPO₄. The novel PB-g-C₃N₄ exhibited excellent optical and electrical properties and the photocatalytic elimination efficiency for atrazine (AT, can make feminization of male frogs in the wild, and even induce reproductive cancers in humans.) has been greatly improved compared with the pristine g-C₃N₄. The results of characterization techniques indicate that the introduced B and P atoms most probably to substitute for sp²-hybridized C atoms in triazine rings. O₂^- and h⁺ are the dominant active species to induce the elimination of AT demonstrated by the radical-trapping experiments. And a possible elimination pathway is proposed according to the detected main intermediates. In addition, PB-g-C₃N₄ was applied to the simultaneous photocatalytic elimination of 9 triazine herbicides, and the effects of different initial concentrations, pH, fulvic acid (FA) and ion species on their elimination effects were studied. And it was proved that the photocatalytic performance of PB-g-C₃N₄ did not significant decrease after 4 times of reuse.

An integrated strategy for rapid on-site screening and determination of prometryn residues in herbs

We produced a prometryn-specific monoclonal antibody and propose a strategy for convenient on-site detection of prometryn residues in herbs for the first time. This strategy has perfect applicability in a complex herbal medicine matrix. The strategy combines a semiquantitative immunochromatographic strip assay with a heterologous indirect competitive ELISA. When there was no matrix interference, the ELISA had a half-maximal inhibitory concentration of 2.6 ng·mL^-1 and a limit of detection of 0.2 ng·mL^-1. The immunochromatographic strip assay can be completed within 5 min with a visual limit of detection of 1 ng·mL^-1. Although the sample matrix had different effects on the sensitivity of the antibody, excellent repeatability and accuracy were achieved. The method was successfully applied for the screening and determination of prometryn residue in multiple complex herb samples for the first time, and the results were in good agreement with those obtained by liquid chromatography-tandem mass spectrometry. The proposed strategy is rapid, of high-throughput, and of low cost, and may be a promising choice for on-site detection of prometryn in different kinds of herbs. Graphical abstract.

Analysis of the pesticide behavior in Chaenomelis speciosa and the role of digestive enzyme in vitro oral bioaccessibility

Problems with pesticide residues in medicinal and edible plant have received great attention. The dietary exposure risk induced by presence of pesticide residues depends on its release from the food matrix, i.e., its bioaccessibility. The bioaccessibility of pesticide residues in human food is poorly understood and thus, we used in vitro digestive method to measure the bioaccessibility of six pesticides in Chaenomelis speciosa. Results showed that the lower and upper boundary bioaccessibility values of the six pesticides in C. speciosa was 4.26 and 86.52%, and the bioaccessibility varied for the pesticide types and digestion phase. The α-amylase and pancreatin play an important role in vitro bioaccessibility. Our findings suggest that risk assessment studies should be taken into account the pesticide metabolism, and that previous studies may have underestimated pesticide bioaccessibility.

Analysis of exposure to pesticide residues from Traditional Chinese Medicine

The safety of Traditional Chinese Medicine (TCM) is of concern worldwide. Herein, Paeoniae Radix Alba, Chaenomelis Fructus and Moutan Cortex, representing three medicinal components, were subjected to toxicological analysis to investigate possible pesticide contamination. Exposure using a point estimate model identified 47 residues that were simultaneously validated by the QuEChERS-UPLC-MS/MS method, which is sufficiently reliable for measuring residue concentrations. Of the 313 samples tested, 94.57% contained pesticide residues, with concentrations ranging from 0.10 to 1199.84 μg kg^-1, of which >83.17% contained 4-15 different residues. Carbendazim was the most frequently detected pesticide (>85%), and procymidone, pendimethalin and phoxim were also abundant (median concentration = 15.33-623.12 μg kg^-1). Risk assessment based on the hazard quotient/hazard index (HQ/HI) approach revealed that exposure to pesticide residues in all three TCMs (95th percentile) were far below levels that might pose a health risk. However, insecticides contributed to cumulative exposure, especially phoxim, and worryingly, several banned pesticides were detected. The results are of theoretical and practical value for evaluating the safety TCMs, and could improve their quality and safety.

Vortex-assisted deep eutectic solvent reversed-phase liquid-liquid microextraction of triazine herbicides in edible vegetable oils

In this study, four triazine herbicides-namely, simazine, ametryn, prometryn and terbuthylazine-were separated and determined using high-performance liquid chromatography coupled with ultraviolet detector (HPLC-UVD). The deep eutectic solvent (DES) formed by tetrabutylammonium chloride ([N₄₄₄₄]Cl, TBA) and ethylene glycol (EG) was selected as the extraction solvent of vortex-assisted reversed-phase liquid-liquid microextraction (VA-RPLLME). The application of the hydrophilic DES expands the range of choice for LLME. The experimental parameters affecting the extraction recoveries, including the amount of the DES, the sample volume and the vortex time, were investigated and optimized by the design of experiments (DoE) methodology. A quadratic model, namely central composite face-centered (CCF) design featuring 20 runs was used instead of the conventional trial and error approach. Under optimum conditions, the limits of determination (LODs) of the method were 0.60-1.50 μg L^-1. The enrichment factors for the analytes ranged from 27 to 31. The extraction recoveries were in the range of 84.1-104.9%, and the intra-day, inter-day and intermediate relative standard deviations (RSDs) were less than 8.4%. Finally, the method was applied for the determination of triazine herbicides in vegetable oil samples. The obtained recoveries were in the range of 60.1-107.2% and RSDs were lower than 8.1%. In general, VA-RPLLME can be complementary to the present available methods for the determination of triazine herbicides in vegetable oil samples.

Development of a liquid-phase microextraction based on the freezing of a deep eutectic solvent followed by HPLC-UV for sensitive determination of common pesticides in environmental water samples

In this research, a new extraction method based on liquid-phase microextraction and the freezing of deep eutectic solvent has been developed for the determination of pesticides in water prior to their analysis by HPLC-UV.