Remediation of aristolochic acid-contaminated soil by an effective advanced oxidation process

Biomimetic microfluidic chips for toxicity assessment of environmental pollutants

Various types of pollutants widely present in environmental media, including synthetic and natural chemicals, physical pollutants such as radioactive substances, ultraviolet rays, and noise, as well as biological organisms, pose a huge threat to public health. Therefore, it is crucial to accurately and effectively explore the human physiological responses and toxicity mechanisms of pollutants to prevent diseases caused by pollutants. The emerging toxicological testing method biomimetic microfluidic chips (BMCs) exhibit great potential in environmental pollutant toxicity assessment due to their superior biomimetic properties. The BMCs are divided into cell-on-chips and organ-on-chips based on the distinctions in bionic simulation levels. Herein, we first summarize the characteristics, emergence and development history, composition and structure, and application fields of BMCs. Then, with a focus on the toxicity mechanisms of pollutants, we review the applications and advances of the BMCs in the toxicity assessment of physical, chemical, and biological pollutants, respectively, highlighting its potential and development prospects in environmental toxicology testing. Finally, the opportunities and challenges for further use of BMCs are discussed.

Development and Application of a Comprehensive Nontargeted Screening Strategy for Aristolochic Acid Analogues

Aristolochic acid analogs (AAAs) are naturally occurring carcinogenic and toxic compounds that pose a safety threat to pharmaceuticals and the environment. It is challenging to screen AAAs due to their lack of characteristic mass spectral fragmentation and their presence of structural diversity. A comprehensive nontargeted screening strategy was proposed by taking into account diverse factors and incorporating various self-developed techniques, and a Python3-based toolkit called AAAs_finder was developed for its implementation. The main procedures consist of virtual structure and ultraviolet and visible (UV) spectra database creation, exact mass and UV spectra-based suspect data extraction, tandem mass spectra (MS/MS) anthropomorphic interpretation, and multicondition retention time (RT) prediction-based candidate structures ranking. To initially assess screening feasibility, eight hypothetical unknown samples were subjected to nontargeted screening using the AAAs_finder toolkit and two other advanced tools. The results showed that the former successfully identified all, while the latter two only managed to identify two and three, respectively, indicating that our strategy was more feasible. After that, the strategy was carefully evaluated for false positives and false negatives, instrument dependence, reproducibility, and sensitivity. After the evaluation, the strategy was successfully applied to the screening of AAAs in real samples, such as herbal medicine, spiked soil, and water. Overall, this study proposed a nontargeted screening strategy and toolkit independent of characteristic mass spectral fragmentation and able to overcome challenges posed by structural diversity for the AAAs screening, which is also valuable for other classes of compounds.

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.

Aristolochic acid-associated cancers: a public health risk in need of global action

Aristolochic acids (AAs) are a group of naturally occurring compounds present in many plant species of the Aristolochiaceae family. Exposure to AA is a significant risk factor for severe nephropathy, and urological and hepatobiliary cancers (among others) that are often recurrent and characterized by the prominent mutational fingerprint of AA. However, herbal medicinal products that contain AA continue to be manufactured and marketed worldwide with inadequate regulation, and possible environmental exposure routes receive little attention. As the trade of food and dietary supplements becomes increasingly globalized, we propose that further inaction on curtailing AA exposure will have far-reaching negative effects on the disease trends of AA-associated cancers. Our Review aims to systematically present the historical and current evidence for the mutagenicity and carcinogenicity of AA, and the effect of removing sources of AA exposure on cancer incidence trends. We discuss the persisting challenges of assessing the scale of AA-related carcinogenicity, and the obstacles that must be overcome in curbing AA exposure and preventing associated cancers. Overall, this Review aims to strengthen the case for the implementation of prevention measures against AA's multifaceted, detrimental and potentially fully preventable effects on human cancer development.

Efficient catalytic degradation of alkanes in soil by a novel heterogeneous Fenton catalyst of functionalized magnetic biochar

In this study, sodium dodecyl sulfate (SDS) functionalized magnetic biochar (SDS-Fe@BC) was successfully prepared. Compared to other traditional heterogeneous Fenton catalysts, more total petroleum hydrocarbons (TPH) (3499.40 mg kg^-1) was adsorbed from soil to the surface of SDS-Fe@BC through hydrophobic interaction between alkyls in alkanes and SDS-Fe@BC, which formed an efficient interface oxidation system. In SDS-Fe@BC-mediated heterogeneous Fenton system, 10,191.41 mg kg^-1 (88.10%) TPH was degraded in the presence of 400 mM H₂O₂, which was 1.38-5.67 folds than that of H₂O₂ alone, Fe²⁺, zero valent iron (ZVI), Fe₃O₄, pristine biochar (BC), and Fe@BC. Moreover, all individual alkanes were efficiently degraded (>75%), and the higher the initial amount of individual alkane, the more the degradative amount in the SDS-Fe@BC/H₂O₂ system. Additionally, TPH degradation was highly related to the mass ratio of SDS/Fe@BC, H₂O₂ concentration, SDS-Fe@BC dosage, and initial pH in the SDS-Fe@BC/H₂O₂ system, and the optimal values were 1:5, 400 mM, 50 mg g^-1, and pH 7, respectively. Radical quenching experiments revealed that hydroxyl radicals (•OH) generated on the surface of SDS-Fe@BC was the dominated reactive oxidative species (ROS) responsible for alkanes degradation. After five cycles, SDS-Fe@BC still remained a high catalytic activity for alkanes degradation (73.21%), showing its excellent reusability. This study proved that the SDS-Fe@BC can be used as a potential heterogeneous Fenton catalyst for petroleum-contaminated soil remediation.

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.

Recent Developments in Advanced Oxidation Processes for Organics-Polluted Soil Reclamation

Soil pollution has become a substantial environmental problem which is amplified by overpopulation in different regions. In this review, the state of the art regarding the use of Advanced Oxidation Processes (AOPs) for soil remediation is presented. This review aims to provide an outline of recent technologies developed for the decontamination of polluted soils by using AOPs. Depending on the decontamination process, these techniques have been presented in three categories: the Fenton process, sulfate radicals process, and coupled processes. The review presents the achievements of, and includes some reflections on, the status of these emerging technologies, the mechanisms, and influential factors. At the present, more investigation and development actions are still desirable to bring them to real full-scale implementation.

Quantitation of Protein Adducts of Aristolochic Acid I by Liquid Chromatography-Tandem Mass Spectrometry: A Novel Method for Biomonitoring Aristolochic Acid Exposure

Emerging evidence suggests that chronic exposure to aristolochic acids (AAs) is one of the etiological pathways leading to chronic kidney disease (CKD). Due to the traditional practice of herbal medicine and AA-containing plants being used extensively as medicinal herbs, over 100 million East Asians are estimated to be at risk of AA poisoning. Given that the chronic nephrotoxicity of AAs only manifests itself after decades of exposure, early diagnosis of AA exposure could allow for timely intervention and disease risk reduction. However, an early detection method is not yet available, and diagnosis can only be established at the end stage of CKD. The goal of this study was to develop a highly sensitive and selective method to quantitate protein adducts of aristolochic acid I (AAI) as a biomarker of AA exposure. The method entails the release of protein-bound aristolactam I (ALI) by heat-assisted alkaline hydrolysis, extraction of ALI, addition of internal standard, and quantitation by liquid chromatography-tandem mass spectrometric analysis. Accuracy and precision of the method were critically evaluated using a synthetic ALI-containing glutathione adduct. The validated method was subsequently used to detect dose-dependent formation of ALI-protein adducts in human serum albumin exposed to AAI and in proteins isolated from the tissues and sera of AAI-exposed rats. Our time-dependent study showed that ALI-protein adducts remained detectable in rats even at 28 days postdosing. It is anticipated that the developed method will fill the technical gap in diagnosing AA intoxication and facilitate the biomonitoring of human exposures to AAs.

Analysis of aristolochic acids in Houttuynia cordata by liquid chromatography-tandem mass spectrometry

Houttuynia cordata (H. cordata) is a popular vegetable in Asian countries and is also used extensively as herbal medicine in treating various diseases. H. cordata contains aristolactams, which have a similar Chinese name as aristolochic acids (AAs); hence, an emerging concern in the greater China region has arisen about the potential linkage between H. cordata and aristolochic acid nephropathy (AAN). However, only a single study has tested for the presence of AAs in H. cordata samples, and the analysis was limited by the analytical sensitivity of the method. Thus, further analysis of AAs in H. cordata using analytical method of higher sensitivity is needed to alleviate public anxiety over the use of this popular vegetable. In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was used to analyze H. cordata samples for the natural existence of aristolochic acid I (AA-I) and aristolochic acid II (AA-II), which are the most carcinogenic and nephrotoxic compounds in the AA family. After evaluating the method performance by fortifying blank samples with three concentrations of AAs, the validated method was applied to identify AA-I and AA-II in both fresh and sun-dried H. cordata samples (n = 20) collected from different cities in China. The LC-MS/MS method achieved method detection limits (MDLs) as low as 2 ng/g of AAs in H. cordata. Analysis of the collected fresh and sun-dried H. cordata samples revealed that AA-I and AA-II either do not exist naturally in H. cordata or exist at concentrations below the MDLs. Therefore, it is not very likely that consumption of H. cordata will result in AAN because AA-I and AA-II, the nephrotoxic and carcinogenic culprits of AAN, are not produced naturally in the plant or are produced at levels that do not pose a risk of AAN.