On-line enrichment and determination of aristolochic acid in medicinal plants using a MOF-based composite monolith as adsorbent

Rapid and selective removal of aristolochic acid I in natural products by vinylene-linked iCOF resins

Rapid, efficient, and selective removal of toxicants such as aristolochic acid I (AAI) from complex natural product systems is of great significance for the safe use of herbal medicines or medicine-food plants. Addressing this challenge, we develop a high-performance separation approach based on ionic covalent organic frameworks (iCOFs) to separate and remove AAI. Two vinylene-linked iCOFs (NKCOF-46-Br- and NKCOF-55-Br-) with high crystallinity are fabricated in a green and scalable fashion via a melt polymerization synthesis method. The resulting materials exhibit a uniform morphology, high stability, fast equilibrium time, and superior affinity and selectivity for AAI. Compared to conventional separation media, NKCOF-46-Br- and NKCOF-55-Br- achieve the record high adsorption capacities of 246.0 mg g-1 and 178.4 mg g-1, respectively. Various investigations reveal that the positively charged framework and favorable pore microenvironment of iCOFs contribute to their high selectivity and adsorption efficiency. Moreover, the iCOFs exhibit excellent biocompatibility by in vivo toxicity assays. This study paves a new avenue for the rapid, selective and efficient removal of toxicants from complex natural systems.

Multivariate surface self-assembly strategy to fabricate ionic covalent organic framework surface grafting monolithic sorbent for enrichment of aristolochic acids prior to high performance liquid chromatography analysis

Herein, an ionic covalent organic framework (iCOF) surface grafting monolithic sorbent was prepared by the multivariate surface self-assembly strategy for in-tube solid-phase microextraction (SPME) of trace aristolochic acids (AAs) in serum, traditional Chinese medicines (TCMs) and Chinese patent drug. Via adjusting the proportion of ionic COF building block during the self-assembly, the density of quaternary ammonium ions in the iCOF was modulated for the enhanced adsorption of AAs. The successful preparation of iCOF surface grafting monolithic sorbent was confirmed by different means. A multiple mode mechanism involving π-π stacking, hydrophobic, electrostatic and hydrogen-bonding interactions was primarily attributed to the adsorption. Several in-tube SPME operating conditions, such as the dosage of ionic COF building block, ACN percentage and TFA percentage in the sampling solution, ACN percentage and TFA percentage in eluent and the collection time span, were optimized to develop the online in-tube SPME-HPLC method for analysis of AAs. Under the optimized conditions, a good linearity was obtained in the concentration range of 20-1000 ng/mL for target AAs in serum samples, the limits of detection (LODs) were less than 10 ng/mL, while the recoveries ranged from 90.3 % to 98.7 % with RSDs (n = 5) below 7.9 %. This study developed a feasible approach to iCOF functionalized monolithic sorbent for SPME and further exhibited the vast potential for the application of COF based monolithic sorbent in sample preparation.

Detection and Removal of Aristolochic Acid in Natural Plants, Pharmaceuticals, and Environmental and Biological Samples: A Review

Aristolochic acids (AAs) are a toxic substance present in certain natural plants. Direct human exposure to these plants containing AAs leads to a severe and irreversible condition known as aristolochic acid nephropathy (AAN). Additionally, AAs accumulation in the food chain through environmental mediators can trigger Balkan endemic nephropathy (BEN), an environmental variant of AAN. This paper presents a concise overview of the oncogenic pathways associated with AAs and explores the various routes of environmental exposure to AAs. The detection and removal of AAs in natural plants, drugs, and environmental and biological samples were classified and summarized, and the advantages and disadvantages of the various methods were analyzed. It is hoped that this review can provide effective insights into the detection and removal of AAs in the future.

Ultrasound-assisted adsorption of organic dyes in real water samples using zirconium (IV)-based metal-organic frameworks UiO-66-NH2 as an adsorbent

The utilization of dye adsorption through metal-organic frameworks represents an eco-friendly and highly effective approach in real water treatment. Here, ultrasound assisted adsorption approach was employed for the remediation of three dyes including methylene blue (MB), malachite green (MG), and congo red (CR) from real water samples using zirconium(IV)-based adsorbent (UiO-66-NH2). The adsorbent was characterized for structural, elemental, thermal and morphological features through XRD, XPS, FTIR, thermogravimetric analysis, SEM, BET , and Raman spectroscopy. The adsorption capacity of adsorbent to uptake the pollutants in aqueous solutions was investigated under different experimental conditions such as amount of UiO-66-NH2 at various contact durations, temperatures, pH levels, and initial dye loading amounts. The maximum removal of dyes under optimal conditions was found to be 938, 587, and 623 mg g-1 towardMB, MG, and CR, respectively. The adsorption of the studied dyes on the adsorbent surface was found to be a monolayer and endothermic process. The probable mechanism for the adsorption was chemisorption and follows pseudo-second-order kinetics. From the findings of regeneration studies, it was deduced that the adsorbent can be effectively used for three consecutive cycles without any momentous loss in its adsorption efficacy. Furthermore, UiO-66-NH2 with ultrasound-assisted adsorption might help to safeguard the environment and to develop new strategies for sustainability of natural resources.

Fe3O4@UiO-66-NH2 based on magnetic solid phase extraction for determination of organic UV filters in environmental water samples

In this work, a nanocomposite structured magnetic metal-organic framework named as Fe3O4@UiO-66-NH2 was prepared via a simple hydrothermal approach. The as-mentioned nanocomposite was characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and the Brunauer-Emmett-Teller (BET) techniques. Using the Fe3O4@UiO-66-NH2 as a nanosorbent, an easy and highly effective approach was developed to preconcentrate nine organic UV filters before gas chromatography-mass spectrometry (GC-MS) analysis. Different conditions influencing the extraction efficiency encompassing the sorbent amount, nature and volume of desorption solvent, desorption time, pH of the sample, and extraction time, were examined. Under the optimal experimental parameters, the Fe3O4@UiO-66-NH2-based magnetic solid phase extraction and GC-MS (MSPE-GC-MS) demonstrated linearity in the range of 0.03-1500 ng/L (R2 ≥ 0.9974) and the reproducibility, expressed as RSD, was ≤7.5%. The limits of detection ranged between 0.01 and 0.07 ng/L and limits of quantification were in the range of 0.03-0.4 ng/L. Finally, the suggested approach was satisfactorily utilized to determine nine organic UV filters in different water samples (analytical recoveries between 86.5% and 104.2%).

Preparation of COPs Mixed Matrix Membrane for Sensitive Determination of Six Sulfonamides in Human Urine

In this study, TpDMB-COPs, a specific class of covalent organic polymers (COPs), was synthesized using Schiff-base chemistry and incorporated into a polyvinylidene fluoride (PVDF) polymer for the first time to prepare COPs mixed matrix membranes (TpDMB-COPs-MMM). A membrane solid-phase extraction (ME) method based on the TpDMB-COPs-MMM was developed to extract trace levels of six sulfonamides from human urine identified by high-performance liquid chromatography (HPLC). The key factors affecting the extraction efficiency were investigated. Under the optimum conditions, the proposed method demonstrated an excellent linear relationship in the range of 3.5-25 ng/mL (r2 ≥ 0.9991), with the low limits of detection (LOD) between 1.25 ng/mL and 2.50 ng/mL and the limit of quantification (LOQ) between 3.50 ng/mL and 7.00 ng/mL. Intra-day and inter-day accuracies were below 5.0%. The method's accuracy was assessed by recovery experiments using human urine spiked at three levels (7-14 ng/mL, 10-15 ng/mL, and 16-20 ng/mL). The recoveries ranged from 87.4 to 112.2% with relative standard deviations (RSD) ≤ 8.7%, confirming the applicability of the proposed method. The developed ME method based on TpDMB-COPs-MMM offered advantages, including simple operation, superior extraction affinity, excellent recycling performance, and easy removal and separation from the solution. The prepared TpDMB-COPs-MMM was demonstrated to be a promising adsorbent for ME in the pre-concentration of trace organic compounds from complex matrices, expanding the application of COPs and providing references for other porous materials in sample pre-treatment.

A dispersive solid-phase extraction method for the determination of Aristolochic acids in Houttuynia cordata based on MIL-101(Fe): An analytes-oriented adsorbent selection design

In view of the molecular structure of Aristolochic acid I (AA-I) and Aristolochic acid II (AA-II), MIL-101(Fe) was selected as the sorbent to develop a dispersive solid-phase extraction (d-SPE) method for capturing the two analytes from Houttuynia cordata. The interactions between the sorbent and analytes were investigated by FT-IR, XPS and UV-Vis DRS spectra. The optimized method demonstrated good linearity with R² > 0.9999. The limit of detections (LODs) were 0.007 mg/L and 0.014 mg/L for AA-I and AA-II, respectively, lower than the limit stipulated by Chinese Pharmacopoeia (0.001 %, w/w). The recoveries for AA-I and AA-II were within the range of 73.3-106.4 %. The precisions of intra-day and inter-day were 0.9-5.8 % and 2.1-5.8 %, respectively. Thus, the established method demonstrated to be efficient and reliable to determine AA-I and AA-II in Houttuynia cordata.

Aristolocholic acid I promotes renal tubular epithelial fibrosis by upregulating matrix metalloproteinase-9 expression via activating the C3a/C3aR axis of macrophages

Aristolochic acid I (AAI) can cause nephrotoxicity and is characterized by interstitial fibrosis. The C3a/C3aR axis of macrophages and matrix metalloproteinase-9 (MMP-9) play important roles in fibrosis, but whether they are involved in AAI-induced renal interstitial fibrosis and are related remains to be elucidated. In this study, we investigated whether C3a/C3aR axis of macrophages promotes renal interstitial fibrosis by regulating MMP-9 in aristolochic acid nephropathy (AAN). Intraperitoneal injection of AAI for 28 days successfully induced AAN in C57bl/6 mice. The content of C3a in the kidney of AAN mice was increased, and there was a significant distribution of macrophages in the renal tubules. The same results were observed in the in vitro experiment. We also explored the role and mechanism of macrophages after AAI administration in the epithelial-mesenchymal transformation (EMT) of renal tubular epithelial cells (RTECs) and found that AAI could activate the C3a/C3aR axis of macrophages to upregulate p65 expression in macrophages. p65 upregulated MMP-9 expression in macrophages not only directly but also by promoting the secretion if interleukin-6 by macrophages and then activating STAT3 in RTECs. The upregulation of MMP-9 expression could promote the EMT of RTECs. Taken together, our study demonstrated that the AAI-activated the C3a/C3aR axis of macrophages, which induced MMP-9 production, was one of the causes of renal interstitial fibrosis. Therefore, targeting the C3a/C3aR axis of macrophages is an effective therapeutic strategy for the prevention and treatment of renal interstitial fibrosis in AAN.

Aristolochic acid I as an emerging biogenic contaminant involved in chronic kidney diseases: A comprehensive review on exposure pathways, environmental health issues and future challenges

Described in the 1950s, Balkan Endemic Nephropathy (BEN) has been recognized as a chronic kidney disease (CKD) with clinical peculiarities and multiple etiological factors. Environmental contaminants - aromatic compounds, mycotoxins and phytotoxins like aristolochic acids (AAs) - polluting food and drinking water sources, were incriminated in BEN, due to their nephrotoxic and carcinogenic properties. The implication of AAs in BEN etiology is currently a highly debated topic due to the fact that they are found within the Aristolochiaceae plants family, used around the globe as traditional medicine and they were also incriminated in Aristolochic Acid Nephropathy (AAN). Exposure pathways have been investigated, but it is unclear to what extent AAs are acting alone or in synergy with other cofactors (environmental, genetics) in triggering kidney damage. Experimental studies strengthen the hypothesis that AAI, the most studied compound in the AAs class, is a significant environmental contaminant and a most important causative factor of BEN. The aim of this review is to compile information about the natural exposure pathways to AAI, via traditional medicinal plants, soil, crop plants, water, food, air. Data that either supports or contradicts the AAI theory concerning BEN etiology was consolidated and available solutions to reduce human exposure were discussed. Because AAI is a phytotoxin with physicochemical properties that allow its transportation in environmental matrices from different types of areas (endemic, nonendemic), and induce CKDs (BEN, AAN) and urinary cancers through bioaccumulation, this review aims to shed a new light on this compound as a biogenic emerging pollutant.

MIL-101(Fe)@TiO2 nanotube composite material is used for the solid phase extraction of non-steroidal anti-inflammatory drugs under the synergy of multiple interactions

Increasing the adsorption sites and effective interactions between sorbents and the targets can improve the solid-phase extraction (SPE) efficiency. Herein, based on the advantages of MOFs and TiO₂ nanotubes (TiO₂ NTs), an MIL-101(Fe)@TiO₂ NT composite was prepared and applied to extract non-steroidal anti-inflammatory drugs (NSAIDs) from water samples coupled with high performance liquid chromatography (HPLC). Through characterization, it was established that MIL-101(Fe) was effectively composited on the surface and inside the TiO₂ nanotubes, increasing effective adsorption sites. The obtained composite material well retains the structure and functional groups of the two original materials, and while retaining the original force with the target, it achieves a synergistic effect and produces more interactions with the target. Therefore, the extraction efficiency was greatly improved. The recovery efficiency reached 97.7-105.1% with an RSD of less than 6.71%, the detection limit was 0.1-0.2 μg L^-1, and the linear range was 1-200 μg L^-1 with a determination coefficient of 0.9972-0.9994. Owing to the stability of the two original materials, the composite material could be recycled and reused to extract NSAIDs up to 15 times without a loss of the recovery rate. Satisfactory results were obtained when it was used to extract NSAIDs from the Yellow River. These results indicate that the synthesized MIL-101(Fe)@TiO₂ NT material is a promising sorbent to extract NSAIDs at trace concentrations with high efficiency and long lifetimes.

Solid-Phase Extraction of Aristolochic Acid I from Natural Plant Using Dual Ionic Liquid-Immobilized ZIF-67 as Sorbent

(1) Background: ZIF-67 is one of the most intriguing metal–organic frameworks already applied in liquid adsorption. To increase its adsorption performance, dual ionic liquids were immobilized on ZIF-67 in this research; (2) Methods: The obtained sorbent was used to adsorb aristolochic acid I (AAI) in standard solutions. Then, the sorbent was applied in solid-phase extraction to remove AAI from Fibraurea Recisa Pierre extracted solution. (3) Results: By analyzing the adsorption models, the highest adsorption capacity of immobilized sorbent (50.9 mg/g) was obtained at 25 °C within 120 min. In the SPE process, 0.02 mg of AAI was removed per gram of herbal plant, the adequate recoveries were in the range of 96.2–100.0%, and RSDs were 3.5–4.0%; (4) Conclusions: The provided experimental data revealed that ZIF-67@EIM-MIM was an excellent potential sorbent to adsorb and remove AAI from herbal plant extract, and the successful separation indicated that this sorbent could be an ideal material for the pretreatment of herbal plants containing AAI.