Pharmacokinetics of the Recalcitrant Drug Lamotrigine: Identification and Distribution of Metabolites in Cucumber Plants

A framework to assess pharmaceutical accumulation in crops: from wastewater irrigation to consumption

The reuse of treated wastewater for irrigation can inadvertently introduce a suite of emerging contaminants such as pharmaceuticals into agri-ecosystems. However, current monitoring efforts to characterise exposure usually focus on a limited range of analytes. A modelling framework was developed that employs a sequence of pre-developed models to predict accumulative potential in a model crop, Zea mays (corn), using chemical structure and excretion rate as the only model inputs. Z. mays was selected as the model crop as it is a major food source, stands as one of the highest cultivated crops globally, and is characterised as having a medium uptake potential. The framework was used to predict uptake in Z. mays in three regions characteristic of high wastewater reuse (Australia, the US and the Middle East). Despite regional and plant specific differences, 72.7 % of the calculated concentrations were within a factor of ten of those reported in the literature. Topiramate, furosemide, and gemfibrozil were observed to accumulate to the greatest extent in Z. mays, predicted concentrations ranged between 50.27 and 418.01 ng/g (dw) for the top 10. Acids predominantly accumulated in leaves and fruit whereas a higher proportion of bases were predicted to accumulate in the roots. To the best of our knowledge 56.7 % of the 30 highest-ranked pharmaceuticals have not been previously documented in existing literature or monitoring campaigns. This presented framework demonstrates a method to assess risk posed by pharmaceutical compounds with limited experimental data.

Impact of the wastewater treatment technology and storage on micropollutant profiles during reclaimed water irrigation: A wide-scope HRMS screening in a water-soil-lettuce-leachate system

In recent decades, climate change and global warming have intensified water scarcity, while the growing global population demands have increased. Reclaimed water (RW) has become essential, offering a viable alternative for crop irrigation in line with circular economy principles. However, although RW reuse is crucial for addressing water shortages, the presence of micropollutants still poses a challenge. The potential for micropollutants to be taken up by crops and enter the food chain still raises significant scientific concern. This work studies RW treated by conventional activated sludge followed by sand filtration and chlorination (CAS+SFC-RW) and membrane-bioreactor-treated RW (MBR-RW) in terms of micropollutant concentrations, providing insights into the differences in micropollutant profiles between the two treatments. The results demonstrate that MBR-RW generally exhibits lower cumulative concentrations of target analytes. However, the study also indicates that the storage of RW for irrigation significantly affects the presence of micropollutants, contributing to their degradation, increase or persistence. Soil analysis revealed fewer detectable micropollutants in the topsoil (0-20 cm) compared to RW, likely attributed to attenuation processes, and more micropollutants (both with respect to concentration and number) compared to deeper soil layers. Carbamazepine, 10,11-epoxide-carbamazepine, and telmisartan were found to migrate to deeper soil levels. The analysis revealed 13 micropollutants in lettuce irrigated with CAS+SFC-RW and 8 with MBR-RW, with carbamazepine and sulfamethoxazole being the most abundant. These differences are likely driven by the physicochemical properties of the compounds and plant-specific factors. Leachates examination showed the potential for contaminants to leach through soil, posing a risk for groundwater contamination. The study showed that the presence of micropollutants in RW is not directly associated with their presence in soil or lettuce, underscoring the need for regulatory policies that address not only their presence in RW but their eventual fate within the agricultural and environmental context.

Accumulation and Subcellular Distribution Patterns of Carbamazepine in Hydroponic Vegetables

Pharmaceutical and Personal Care Products (PPCPs), such as carbamazepine, enter the food chain through wastewater irrigation, posing risks to ecosystems and human health. However, research on the translocation and subcellular distribution of carbamazepine in vegetables is limited. Herein, we used 14C-labeled carbamazepine as a tracer to investigate its removal, accumulation, and subcellular compartmentalization in hydroponic vegetable systems. Results showed carbamazepine accumulated in Chinese flowering cabbage and water spinach with removal efficiencies of 93.0-93.2%. The compound was absorbed by roots and translocated to aboveground tissues, particularly in bottom leaves, reaching 90.3 μmol/kg after 768 h, as confirmed by autoradiography. Subcellular analysis indicated that carbamazepine is predominantly distributed in root organelles and in the soluble fraction of leaves and stems. A strong correlation (R2 > 0.800) was observed between root enrichment coefficients and log KOW for caffeine, carbamazepine, and kresoxim-methyl. Higher lipid content in water spinach roots (2.07%) significantly enhanced upward transport, underscoring lipid content's role in translocation. Additionally, a higher xylem content in the plant accelerated the transport of carbamazepine. This study provides key insights into the environmental behavior of organic pollutants, supporting efforts in environmental and health protection.

Pharmaceutical metabolite identification in lettuce (Lactuca sativa) and earthworms (Eisenia fetida) using liquid chromatography coupled to high-resolution mass spectrometry and in silico spectral library

Pharmaceuticals released into the aquatic and soil environments can be absorbed by plants and soil organisms, potentially leading to the formation of unknown metabolites that may negatively affect these organisms or contaminate the food chain. The aim of this study was to identify pharmaceutical metabolites through a triplet approach for metabolite structure prediction (software-based predictions, literature review, and known common metabolic pathways), followed by generating in silico mass spectral libraries and applying various mass spectrometry modes for untargeted LC-qTOF analysis. Therefore, Eisenia fetida and Lactuca sativa were exposed to a pharmaceutical mixture (atenolol, enrofloxacin, erythromycin, ketoprofen, sulfametoxazole, tetracycline) under hydroponic and soil conditions at environmentally relevant concentrations. Samples collected at different time points were extracted using QuEChERS and analyzed with LC-qTOF in data-dependent (DDA) and data-independent (DIA) acquisition modes, applying both positive and negative electrospray ionization. The triplet approach for metabolite structure prediction yielded a total of 3762 pharmaceutical metabolites, and an in silico mass spectral library was created based on these predicted metabolites. This approach resulted in the identification of 26 statistically significant metabolites (p < 0.05), with DDA + and DDA - outperforming DIA modes by successfully detecting 56/67 sample type:metabolite combinations. Lettuce roots had the highest metabolite count (26), followed by leaves (6) and earthworms (2). Despite the lower metabolite count, earthworms showed the highest peak intensities, closely followed by roots, with leaves displaying the lowest intensities. Common metabolic reactions observed included hydroxylation, decarboxylation, acetylation, and glucosidation, with ketoprofen-related metabolites being the most prevalent, totaling 12 distinct metabolites. In conclusion, we developed a high-throughput workflow combining open-source software with LC-HRMS for identifying unknown metabolites across various sample types.

Alien emergent aquatic plants develop better ciprofloxacin tolerance and metabolic capacity than one native submerged species

Antibiotic pollution and biological invasion pose significant risks to freshwater biodiversity and ecosystem health. However, few studies have compared the ecological adaptability and ciprofloxacin (CIPR) degradation potential between alien and native macrophytes. We examined growth, physiological response, and CIPR accumulation, translocation and metabolic abilities of two alien plants (Eichhornia crassipes and Myriophyllum aquaticum) and one native submerged species (Vallisneria natans) exposed to CIPR at 0, 1 and 10 mg/L. We found that E. crassipes and M. aquaticum's growth were unaffected by CIPR while V. natans was significantly hindered under the 10 mg/L treatment. CIPR significantly decreased the maximal quantum yield of PSII, actual quantum yield of PSII and relative electron transfer rate in E. crassipes and V. natans but didn't impact these photosynthetic characteristics in M. aquaticum. All the plants can accumulate, translocate and metabolize CIPR. M. aquaticum and E. crassipes in the 10 mg/L treatment group showed greater CIPR accumulation potential than V. natans indicated by higher CIPR contents in their roots. The oxidative cleavage of the piperazine ring acts as a key pathway for these aquatic plants to metabolize CIPR and the metabolites mainly distributed in plant roots. M. aquaticum and E. crassipes showed a higher production of CIPR metabolites compared to V. natans, with M. aquaticum exhibiting the strongest CIPR metabolic ability, as indicated by the most extensive structural breakdown of CIPR and the largest number of potential metabolic pathways. Taken together, alien species outperformed the native species in ecological adaptability, CIPR accumulation and metabolic capacity. These findings may shed light on the successful invasion mechanisms of alien aquatic species under antibiotic pressure and highlight the potential ecological impacts of alien species, particularly M. aquaticum. Additionally, the interaction of antibiotic contamination and invasion might further challenge the native submerged macrophytes and pose greater risks to freshwater ecosystems.

Comparative uptake, translocation and metabolism of phenamacril in crops under hydroponic and soil cultivation conditions

Many studies investigate the plant uptake and metabolism of xenobiotics by hydroponic experiments, however, plants grown in different conditions (hydroponic vs. soil) may result in different behaviors. To explore the potential differences, a comparative study on the uptake, translocation and metabolism of the fungicide phenamacril in crops (wheat/rice) under hydroponic and soil cultivation conditions was conducted. During 7-14 days of exposure, the translocation factors (TFs) of phenamacril were greatly overestimated in hydroponic-wheat (3.6-5.2) than those in soil-wheat systems (1.1-2.0), with up to 3.3 times of difference between the two cultivation systems, implying it should be cautious to extrapolate the results obtained from hydroponic to field conditions. M-144 was formed in soil pore water (19.1-29.9 μg/L) in soil-wheat systems but not in the hydroponic solution in hydroponics; M-232 was only formed in wheat shoots (89.7-103.0 μg/kg) under soil cultivation conditions, however, it was detected in hydroponic solution (20.1-21.2 μg/L), wheat roots (146.8-166.0 μg/kg), and shoots (239.2-348.1 μg/kg) under hydroponic conditions. The root concentration factors (RCFs) and TFs of phenamacril in rice were up to 2.4 and 3.6 times higher than that in wheat for 28 days of the hydroponic exposure, respectively. These results highlighted that cultivation conditions and plant species could influence the fate of pesticides in crops, which should be considered to better assess the potential accumulation and transformation of pesticides in crops.

From Water to Water: Insight into the Translocation of Pesticides from Plant Rhizosphere Solution to Leaf Guttation and the Associated Ecological Risks

Plant guttation is an important source of water/nutrients for many beneficial insects, while the presence of pesticides in guttation has been considered as a new exposure route for nontarget insects. This study aimed to elucidate how 15 diverse pesticides are translocated from growth media to guttation by maize plants through a hydroponic experiment. All pesticides were effectively translocated from the growth solution to maize guttation and reached a steady state within 5 days. The strong positive correlation (R2 = 0.43-0.84) between the concentrations of pesticides in guttation and in xylem sap demonstrated that xylem sap was a major source of pesticides in guttation. The relationship between the bioaccumulation of pesticides in guttation (BCFguttation) and the chemical Kow was split into two distinct patterns: for pesticides with log Kow > 3, we identified a good negative linear correlation between log BCFguttation and log Kow (R2 = 0.71); however, for pesticides with log Kow < 3, all data fall close to a horizontal line of BCFguttation ≅ 1, indicating that hydrophilic pesticides can easily pass through the plants from rhizosphere solution to leaf guttation and reach saturation status. Besides, after feeding with pesticide-contaminated guttation, the mortality of honeybees was significantly impacted, even at very low levels (e.g., ∑600 μg/L with a mortality of 93%). Our results provide essential information for predicting the contamination of plant guttation with pesticides and associated ecological risks.