Effects of Heavy Metal Co-Exposure on the formation of DNA Adducts from Aristolochic Acid I: Implications for Balkan Endemic Nephropathy Development.

Accumulated evidence has shown that Balkan endemic nephropathy (BEN) is a multifactorial environmental disease, with exposure to aristolochic acids (AA), and the associated DNA adduct formation, as a key causative factor of BEN development. Here, we show that coexposure to arsenic, cadmium, and iron increases the DNA adduct formation of AA in cultured kidney cells, while exhibiting both an exposure concentration and duration dependence. In contrast, coexposure to calcium and copper showed a decreasing DNA adduct formation. Because DNA damage is responsible for both the nephrotoxicity and carcinogenicity of AA, these results shed greater light on the endemic nature of BEN.

Human UDP-glucuronosyltransferase 1As catalyze aristolochic acid D O-glucuronidation to form a lesser nephrotoxic glucuronide.

ETHNOPHARMACOLOGICAL RELEVANCE: Aristolochic acids (AAs) are naturally occurring nitro phenanthrene carboxylic acids primarily found in plants of the Aristolochiaceae family. Aristolochic acid D (AAD) is a major constituent in the roots and rhizomes of the Chinese herb Xixin (the roots and rhizomes of Asarum heterotropoides F. Schmidt), which is a key material for preparing a suite of marketed Chinese medicines. Structurally, AAD is nearly identical to the nephrotoxic aristolochic acid I (AAI), with an additional phenolic group at the C-6 site. Although the nephrotoxicity and metabolic pathways of AAI have been well-investigated, the metabolic pathway(s) of AAD in humans and the influence of AAD metabolism on its nephrotoxicity has not been investigated yet. AIM OF THE STUDY: To identify the major metabolites of AAD in human tissues and to characterize AAD O-glucuronidation kinetics in different enzyme sources, as well as to explore the influence of AAD O-glucuronidation on its nephrotoxicity. MATERIALS AND METHODS: The O-glucuronide of AAD was biosynthesized and its chemical structure was fully characterized by both 1H-NMR and 13C-NMR. Reaction phenotyping assays, chemical inhibition assays, and enzyme kinetics analyses were conducted to assess the crucial enzymes involved in AAD O-glucuronidation in humans. Docking simulations were performed to mimic the catalytic conformations of AAD in human UDP-glucuronosyltransferases (UGTs), while the predicted binding energies and distances between the deprotonated C-6 phenolic group of AAD and the glucuronyl moiety of UDPGA in each tested human UGT isoenzyme were measured. The mitochondrial membrane potentials (MMP) and reactive oxygen species (ROS) levels in HK-2 cells treated with either AAI, or AAD, or AAD O-glucuronide were tested, to elucidate the impact of O-glucuronidation on the nephrotoxicity of AAD. RESULTS: AAD could be rapidly metabolized in human liver and intestinal microsomes (HLM and HIM, respectively) to form a mono-glucuronide, which was purified and fully characterized as AAD-6-O-ß-D-glucuronide (AADG) by NMR. UGT1A1 was the predominant enzyme responsible for AAD-6-O-glucuronidation, while UGT1A9 contributed to a lesser extent. AAD-6-O-glucuronidation in HLM, HIM, UGT1A1 and UGT1A9 followed Michaelis-Menten kinetics, with the Km values of 4.27 µM, 9.05 µM, 3.87 µM, and 7.00 µM, respectively. Docking simulations suggested that AAD was accessible to the catalytic cavity of UGT1A1 or UGT1A9 and formed catalytic conformations. Further investigations showed that both AAI and AAD could trigger the elevated intracellular ROS levels and induce mitochondrial dysfunction and in HK-2 cells, but AADG was hardly to trigger ROS accumulation and mitochondrial dysfunction. CONCLUSION: Collectively, UGT1A-catalyzed AAD 6-O-glucuronidation represents a crucial detoxification pathway of this naturally occurring AAI analogs in humans, which is very different from that of AAI.

Comprehensive HRMS Screening and Risk Assessments of Aristolochic Acid Analogues in Asari Radix et Rhizoma and Related Commercial Health Products.

Aristolochic acid analogues (AAAs) are well-known toxins. We performed the first comprehensive screening on AAAs in Asari Radix et Rhizoma (underground part of Asarum heterotropoides Schmidt), the only Aristolochiaceae plant widely used in clinical practice. LC-HRMS revealed 70 trace AAAs using polygonal mass defect filtering and precursor ion list strategies, 38 of which were newly discovered in A. heterotropoides. UHPLC-QTrap-MS/MS was then utilized for quantitative/semiquantitative analysis of 26 abundant compounds. Seventeen AAAs were detected from 91 batches of A. heterotropoides and 20 AAAs from 166 consumable products. For 141 Asari-containing proprietary products, aristolactam I and aristolactam II-glucoside exhibited the widest distribution, present in 98% products. AA IVa was the most abundant, detected in 91%. Notably, 60% of the products contained AA I (0.03-0.79 ppm). The safety was assessed using linear extrapolation, permitted daily exposure, cumulative amount, and the margin of exposure. It is recommended that AA I content be limited to 3 ppm.

Mitochondrial uptake of aristolactam I plays a critical role in its toxicity.

Aristolochic acid I (AAI), a component of aristolochic acids, can be converted to the toxic metabolite Aristolactam I (ALI) in vivo which forms aristolactam-nitrenium with delocalized positive charges. It is widely accepted that delocalized lipophilic cations can accumulate in mitochondria due to the highly negatively charged microenvironment of the mitochondrial matrix, but the uptake of ALI by mitochondria is not known. In this study, the cell uptake and mitochondrial localization of ALI, and its subsequent impact on mitochondrial function were investigated. Results show that ALI can rapidly penetrate HK-2 cells without relying on organic anion transporters 1/3 (OAT1/3). The cellular distribution of ALI was found to align with the observed distribution of a mitochondria-selective dye in HK-2 cells. Furthermore, the cell uptake and mitochondrial uptake of ALI were both inhibited by carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone, which induces mitochondrial membrane depolarization. These results suggest that ALI is selectively taken up by mitochondria. Consequently, mitochondrial dysfunction was observed after treatment with ALI. It should be noted that inhibiting OAT1/3 could result in an increased exposure of ALI in vivo and cause more seriously nephrotoxicity. In conclusion, this research reports the mitochondrial uptake of ALI and provides new insight on potential strategies for protection against AAI-induced nephrotoxicity.

Ionizable copolymer functionalized magnetic nanocomposite as an adsorbent for boosting the extraction selectivity of aristolochic acids.

Aristolochic acid nephropathy (AAN) has drawn increasing public attention. Organic anion transporters (OATs) are considered to be responsible for mediating nephrotoxicity of aristolochic acids (AAs), as AAs are typical OAT1 substrates that exhibit anionic properties and contain one hydrophobic domain. Inspired by the OAT1 three-dimensional structure or substrate/protein interactions involved in transport, we designed a magnetic polymeric hybrid, mimicking the effect of basic and aromatic residues of OAT1, for efficient enriching aristolochic acid I (AA I) and aristolochic acid II (AA II) in Traditional Chinese patent medicines (TCPM). N, N-dimethylaminopropyl acrylamide (DMAPAm) was used as a cationic monomer and copolymerized with divinylbenzene (DVB) onto the surface of monodisperse magnetic nanoparticles (denoted as MNs@SiO2T-DvbDam). The magnetic polymer hybrid demonstrated high selectivity and capacity for AAs, which was mainly attributed to (1) electrostatic interactions from the cationic or basic moiety of DMAPAm and (2) the hydrophobic and π-π stacking interactions from the aromatic ring of DVB. Additionally, the surface of the hybrid exhibited amphiphilic property according to the ionization of DMAPAm, thus improving the compatibility of the adsorbent with the aqueous sample matrix. This strategy was proven to be robust in the analysis of real drug samples, which was characterized by a good linearity, high recovery and satisfactory reusability. This work confirmed that the proposed tool could be a promising candidate for enhancing the extraction selectivity of AAs in Traditional Chinese medicines (TCM).

Deep whole-genome analysis of 494 hepatocellular carcinomas.

Over half of hepatocellular carcinoma (HCC) cases diagnosed worldwide are in China1-3. However, whole-genome analysis of hepatitis B virus (HBV)-associated HCC in Chinese individuals is limited4-8, with current analyses of HCC mainly from non-HBV-enriched populations9,10. Here we initiated the Chinese Liver Cancer Atlas (CLCA) project and performed deep whole-genome sequencing (average depth, 120×) of 494 HCC tumours. We identified 6 coding and 28 non-coding previously undescribed driver candidates. Five previously undescribed mutational signatures were found, including aristolochic-acid-associated indel and doublet base signatures, and a single-base-substitution signature that we termed SBS_H8. Pentanucleotide context analysis and experimental validation confirmed that SBS_H8 was distinct to the aristolochic-acid-associated SBS22. Notably, HBV integrations could take the form of extrachromosomal circular DNA, resulting in elevated copy numbers and gene expression. Our high-depth data also enabled us to characterize subclonal clustered alterations, including chromothripsis, chromoplexy and kataegis, suggesting that these catastrophic events could also occur in late stages of hepatocarcinogenesis. Pathway analysis of all classes of alterations further linked non-coding mutations to dysregulation of liver metabolism. Finally, we performed in vitro and in vivo assays to show that fibrinogen alpha chain (FGA), determined as both a candidate coding and non-coding driver, regulates HCC progression and metastasis. Our CLCA study depicts a detailed genomic landscape and evolutionary history of HCC in Chinese individuals, providing important clinical implications.

PSTPIP2 ameliorates aristolochic acid nephropathy by suppressing interleukin-19-mediated neutrophil extracellular trap formation.

Aristolochic acid nephropathy (AAN) is a progressive kidney disease caused by herbal medicines. Proline-serine-threonine phosphatase-interacting protein 2 (PSTPIP2) and neutrophil extracellular traps (NETs) play important roles in kidney injury and immune defense, respectively, but the mechanism underlying AAN regulation by PSTPIP2 and NETs remains unclear. We found that renal tubular epithelial cell (RTEC) apoptosis, neutrophil infiltration, inflammatory factor, and NET production were increased in a mouse model of AAN, while PSTPIP2 expression was low. Conditional knock-in of Pstpip2 in mouse kidneys inhibited cell apoptosis, reduced neutrophil infiltration, suppressed the production of inflammatory factors and NETs, and ameliorated renal dysfunction. Conversely, downregulation of Pstpip2 expression promoted kidney injury. In vivo, the use of Ly6G-neutralizing antibody to remove neutrophils and peptidyl arginine deiminase 4 (PAD4) inhibitors to prevent NET formation reduced apoptosis, alleviating kidney injury. In vitro, damaged RTECs released interleukin-19 (IL-19) via the PSTPIP2/nuclear factor (NF)-κB pathway and induced NET formation via the IL-20Rß receptor. Concurrently, NETs promoted apoptosis of damaged RTECs. PSTPIP2 affected NET formation by regulating IL-19 expression via inhibition of NF-κB pathway activation in RTECs, inhibiting RTEC apoptosis, and reducing kidney damage. Our findings indicated that neutrophils and NETs play a key role in AAN and therapeutic targeting of PSTPIP2/NF-κB/IL-19/IL-20Rß might extend novel strategies to minimize Aristolochic acid I-mediated acute kidney injury and apoptosis.

Aristolochic acid nephropathy (or AAN for short) is a serious condition affecting the kidneys that is caused by certain traditional Chinese medicines containing a compound called aristolochic acid. This compound is known to have harmful effects on kidney tubular epithelial cells, causing increased inflammation and a form of controlled cell death called apoptosis, which can ultimately lead to organ failure. There is currently no effective treatment for AAN, highlighting the need for a deeper understanding of the mechanisms responsible. Previous studies have shown that immune cells called neutrophils infiltrate the kidneys and damage cells in the early stages of AAN. Neutrophils produce web-like structures called neutrophil extracellular traps, which have been identified as potentially contributing to the damage. A protein called PSTPIP2, which regulates inflammation, has also been shown to contribute to other types of kidney injury. To understand how these inflammatory factors might be involved in AAN, Du, Xu et al. genetically engineered mice to produce extra PSTPIP2 protein specifically in their kidneys. When given aristolochic acid, these mice displayed less kidney damage. Further studies of mouse kidney cells showed that PSTPIP2 protects the kidney by suppressing an inflammatory mechanism that leads to the production of neutrophil extracellular traps. By contrast, in models where PSTPIP2 levels were reduced, neutrophil extracellular traps were shown to cause both apoptosis and kidney injury. The findings of Du, Xu et al. show that neutrophil extracellular traps cause cell damage and apoptosis in a mouse model of AAN and that this action can be reduced by increasing the levels of the protein PSTPIP2. This sheds light on the inflammatory mechanisms behind the kidney damage caused by herbal medicines containing aristolochic acid. Additionally, it opens new avenues for studies aiming to find ways to treat AAN, suggesting that targeting PSTPIP2 could be a promising strategy.

Application of duplex sequencing to evaluate mutagenicity of aristolochic acid and methapyrilene in Fisher 344 rats.

Duplex sequencing (DS) is an error-corrected next-generation sequencing (NGS) method that can overcome notorious high error rate from the process of NGS and detect ultralow-frequency mutations. In this study, we evaluated the mutagenicity of aristolochic acid, a known genotoxic carcinogen, and methapyrilene, a known nongenotoxic carcinogen using DS. Four male Fisher 344 rats were treated with aristolochic acid, methapyrilene, or the vehicle control for 6 weeks, liver tissues were collected one day after the treatment, and the DNA was isolated for analysis. The mutation frequency for the aristolochic acid-treated group was significantly increased over the vehicle control (44-fold), whereas no significant difference in the mutation frequency was observed between the methapyrilene-treated and the control groups. The primary type of mutation induced by aristolochic acid was A:T > T:A transversion, which occurred frequently at ApT sites, whereas the major type of mutation in the control and methapyrilene-treated groups was G:C > A:T transition, which occurred frequently at CpG sites. These findings are consistent with previously published data obtained with other in vivo mutation assays. Thus, our results suggest that the DS mutation assay is a promising technology for assessing mutagenicity of chemicals in vivo.

Screening DNA Damage in the Rat Kidney and Liver by Untargeted DNA Adductomics.

Air pollution, tobacco smoke, and red meat are associated with renal cell cancer (RCC) risk in the United States and Western Europe; however, the chemicals that form DNA adducts and initiate RCC are mainly unknown. Aristolochia herbaceous plants are used for medicinal purposes in Asia and worldwide. They are a significant risk factor for upper tract urothelial carcinoma (UTUC) and RCC to a lesser extent. The aristolochic acid (AA) 8-methoxy-6-nitrophenanthro-[3,4-d]-1,3-dioxolo-5-carboxylic acid (AA-I), a component of Aristolochia herbs, contributes to UTUC in Asian cohorts and in Croatia, where AA-I exposure occurs from ingesting contaminated wheat flour. The DNA adduct of AA-I, 7-(2'-deoxyadenosin-N6-yl)-aristolactam I, is often detected in patients with UTUC, and its characteristic A:T-to-T:A mutational signature occurs in oncogenes and tumor suppressor genes in AA-associated UTUC. Identifying DNA adducts in the renal parenchyma and pelvis caused by other chemicals is crucial to gaining insights into unknown RCC and UTUC etiologies. We employed untargeted screening with wide-selected ion monitoring tandem mass spectrometry (wide-SIM/MS2) with nanoflow liquid chromatography/Orbitrap mass spectrometry to detect DNA adducts formed in rat kidneys and liver from a mixture of 13 environmental, tobacco, and dietary carcinogens that may contribute to RCC. Twenty DNA adducts were detected. DNA adducts of 3-nitrobenzanthrone (3-NBA), an atmospheric pollutant, and AA-I were the most abundant. The nitrophenanthrene moieties of 3-NBA and AA-I undergo reduction to their N-hydroxy intermediates to form 2'-deoxyguanosine (dG) and 2'-deoxyadenosine (dA) adducts. We also discovered a 2'-deoxycytidine AA-I adduct and dA and dG adducts of 10-methoxy-6-nitro-phenanthro-[3,4-d]-1,3-dioxolo-5-carboxylic acid (AA-III), an AA-I isomer and minor component of the herbal extract assayed, signifying AA-III is a potent kidney DNA-damaging agent. The roles of AA-III, other nitrophenanthrenes, and nitroarenes in renal DNA damage and human RCC warrant further study. Wide-SIM/MS2 is a powerful scanning technology in DNA adduct discovery and cancer etiology characterization.

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.

No Incidence of Liver Cancer Was Observed in A Retrospective Study of Patients with Aristolochic Acid Nephropathy.

OBJECTIVE: To assess the risk of aristolochic acid (AA)-associated cancer in patients with AA nephropathy (AAN). METHODS: A retrospective study was conducted on patients diagnosed with AAN at Peking University First Hospital from January 1997 to December 2014. Long-term surveillance and follow-up data were analyzed to investigate the influence of different factors on the prevalence of cancer. The primary endpoint was the incidence of liver cancer, and the secondary endpoint was the incidence of urinary cancer during 1 year after taking AA-containing medication to 2014. RESULTS: A total of 337 patients diagnosed with AAN were included in this study. From the initiation of taking AA to the termination of follow-up, 39 patients were diagnosed with cancer. No cases of liver cancer were observed throughout the entire follow-up period, with urinary cancer being the predominant type (34/39, 87.17%). Logistic regression analysis showed that age, follow-up period, and diabetes were potential risk factors, however, the dosage of the drug was not significantly associated with urinary cancer. CONCLUSIONS: No cases of liver cancer were observed at the end of follow-up. However, a high prevalence of urinary cancer was observed in AAN patients. Establishing a direct causality between AA and HCC is challenging.

SGLT2 inhibitor dapagliflozin protects the kidney in a murine model of Balkan nephropathy.

Proximal tubular uptake of aristolochic acid (AA) forms aristolactam (AL)-DNA adducts, which cause a p53/p21-mediated DNA damage response and acute tubular injury. Recurrent AA exposure causes kidney function loss and fibrosis in humans (Balkan endemic nephropathy) and mice and is a model of (acute kidney injury) AKI to chronic kidney disease (CKD) transition. Inhibitors of the proximal tubule sodium-glucose transporter SGLT2 can protect against CKD progression, but their effect on AA-induced kidney injury remains unknown. C57BL/6J mice (15-wk-old) were administered vehicle or AA every 3 days for 3 wk (10 and 3 mg/kg ip in females and males, respectively). Dapagliflozin (dapa, 0.01 g/kg diet) or vehicle was initiated 7 days prior to AA injections. All dapa effects were sex independent, including a robust glycosuria. Dapa lowered urinary kidney-injury molecule 1 (KIM-1) and albumin (both normalized to creatinine) after the last AA injection and kidney mRNA expression of early DNA damage response markers (p53 and p21) 3 wk later at the study end. Dapa also attenuated AA-induced increases in plasma creatinine as well as AA-induced up-regulation of renal pro-senescence, pro-inflammatory and pro-fibrotic genes, and kidney collagen staining. When assessed 1 day after a single AA injection, dapa pretreatment attenuated AL-DNA adduct formation by 10 and 20% in kidney and liver, respectively, associated with reduced p21 expression. Initiating dapa application after the last AA injection also improved kidney outcome but in a less robust manner. In conclusion, the first evidence is presented that pretreatment with an SGLT2 inhibitor can attenuate the AA-induced DNA damage response and subsequent nephropathy.NEW & NOTEWORTHY Recurrent exposure to aristolochic acid (AA) causes kidney function loss and fibrosis in mice and in humans, e.g., in the form of the endemic Balkan nephropathy. Inhibitors of the proximal tubule sodium-glucose transporter SGLT2 can protect against CKD progression, but their effect on AA-induced kidney injury remains unknown. Here we provide the first evidence in a murine model that pretreatment with an SGLT2 inhibitor can attenuate the AA-induced DNA damage response and subsequent nephropathy.

Aristolochic acid I aggravates oxidative stress-mediated apoptosis by inhibiting APE1/Nrf2/HO-1 signaling.

Nephrotoxicity induced by aristolochic acid I (AAI) is related to redox stress and apoptosis. Apurinic/apyrimidine endonuclease 1 (APE1) has antioxidant and anti-apoptotic effects. This study investigated the potential role of APE1 in AAI-induced nephrotoxicity. Renal injury was successfully induced in C57BL/6J mice by intraperitoneal injection of AAI every other day for 28 days. Expressions of APE1, nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase 1 (HO-1) in renal tissues of the model mice was inhibited, accompanied by oxidative damage and apoptosis. Similar results were obtained in vitro in human proximal tubular (HK-2) cells damaged by AAI. In the presence of a low concentration of the APE1 inhibitor E3330, expression of Nrf2 and HO-1 proteins in HK-2 cells was decreased and AAI-induced apoptosis was aggravated. Overexpression of APE1 in HK-2 cells promoted the expression of Nrf2 and HO-1, and alleviated apoptosis and renal injury induced by AAI. The collective findings demonstrate that AAI can inhibit the induction of oxidative stress and apoptosis by the APE1/Nrf2/HO-1 axis, leading to AAI renal injury. Targeting APE1 may be an effective therapeutic strategy to treat AA nephrotoxicity.

New molecular insights into ferroptosis in lung adenocarcinoma progression and pharmacological compounds for targeted therapy.

BACKGROUND: The involvement of ferroptosis has been found in many pathological conditions of the lung. The genetic engineering of ferroptosis-related genes may provide a potential target for the treatment of lung adenocarcinoma (LUAD). METHODS: Nine ferroptosis regulators and markers were collected from FerrDb and their somatic mutations and expressions were analyzed based on The Cancer Genome Atlas (TCGA)-LUAD cohort data. Least absolute shrinkage and selection operator (LASSO) and Cox regression analysis were performed to screen genes significantly associated with ferroptosis. The ferroptosis-related gene signature was constructed using TCGA-LUAD cohort data and was verified using the GSE cohort with pooled data for GSE30219, GSE31210, GSE37745 and GSE50081. Immune microenvironment component and mutation analysis were performed for genes in the ferroptosis-related gene signature. RESULTS: All nine ferroptosis regulators and markers were differentially expressed between normal LUAD tumor tissues and adjacent normal tissues and were related to copy number variation. The expression of 1329 genes were significantly associated with nine ferroptosis regulators and markers in the TCGA-LUAD dataset, five (ALDOA, PLK1, CD47, CENPC and TMOD3) of which were integrated into a ferroptosis-related gene signature to calculate the risk score of LUAD samples, showing a significant correlation with the abundance of immune cell infiltration and the immune score. Molecular docking showed the binding activity of natural active compound quercetin to target proteins ALDOA and CD47, as well as the binding activity of aristolochic acid to PLK1 protein and TMOD3 protein. CONCLUSIONS: In the present study, a ferroptosis-related gene signature with predictive value for LUAD prognosis was constructed, in which the gene was a potential therapeutic target for LUAD. Quercetin and aristolochic acid were potential candidates for inhibiting these targets by directly binding to them and showing high affinity and strong stability.

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.

Investigation of the applicability of the zebrafish model for the evaluation of aristolochic acid-related nephrotoxicity.

BACKGROUND: The risk of compounds/drugs, including aristolochic acid-induced nephrotoxicity remains high and is a significant public health concern. Therefore, it is particularly important to select reasonable animal models for rapid screening and evaluation of different samples with complex chemical systems. The zebrafish (Danio rerio) has been used to study chemical-induced renal toxicity. However, most of the published literature was performed on individual components or drugs, and the key evidence confirming the applicability of zebrafish larvae for the evaluation of aristolochic acid-related nephrotoxicity in complex chemical systems, such as in traditional Chinese medicine (TCM), was insufficient. METHODS: High-performance liquid chromatography (HPLC) was used to determine the content of aristolochic acid (AA) in herbs and Chinese patent medicines. The zebrafish larvae at 4 days post-fertilization (dpf) were used to evaluate the nephrotoxicity of various samples, respectively, based on the phenotype of the kidney and histological, and biochemical. Transcriptome technology was used to investigate the related signaling pathways and potential mechanisms after treatment with AA, which was verified by RT-PCR technology. RESULTS: The results showed that the total amounts of AAI, AAII, and ALI ranged from 0.0004 to 0.1858 g·g-1( %) from different samples, including Aristolochia debilis, Fibraurea recisa, Asarum, Wantongjingu tablets, Jiuweiqianghuo granules, and Xiaoqinglong granules in descending order. Moreover, compared with the negative/blank control, substantial changes in phenotype, histomorphology and biochemical parameters of renal function were observed in the groups challenged with the sublethal concentration of drugs. The transcriptomics results showed the upregulation of most genes in PERK/ATF4/CHOP, ATM/Chk2/p53, Caspase/Bax/Bcl-2a, TGF/Smad/ERK, PI3K/Akt, induced by aristolochic acid analogues, which were essentially consistent with those of the q-RT-PCR experiments, highlighting the similar toxicity response to the previously published article with the other traditional evaluation model. CONCLUSION: The stability, accuracy and feasibility of the zebrafish larval model in screening and evaluating the nephrotoxicity of TCM were validated for the first time on the AAs-related drugs in a unified manner, confirming and promoting the applicability of zebrafish in assessing nephrotoxicity of samples with complex chemical character.

Fabrication of a Simple and Efficient HPLC Reduction Column for Online Conversion of Aristolochic Acids to Aristolactams Prior to Sensitive Fluorescence Detection.

Aristolochic acids (AAs) are nephrotoxic and carcinogenic nitrophenanthrene carboxylic acids produced naturally by plants from the Aristolochia and Asarum genera, which have been used extensively as herbal medicines. In addition to consuming AA-containing herbal medicinal products, there is emerging evidence that humans are also exposed to AA through the environment. In 2022, the World Health Organization (WHO) called for global action to remove AA exposure sources and to implement preventative measures against the development of AA-associated cancers. Herein, we report the development of a simple and efficient iron powder-packed reduction column that allows online post-column conversion of the nonfluorescing AA to its corresponding strongly fluorescing aristolactam (AL), facilitating the sensitive and selective detection of AA in herbal medicinal products, food grain, arable soil, or groundwater samples by high-performance liquid chromatography with fluorescence detection. Moreover, AL, a group of naturally occurring derivatives of AA that have demonstrated toxicity to cultured bacteria, human cells, and rats, is monitored and quantified simultaneously with AA in one single run without sacrificing sensitivity. In comparison with existing analytical methods for AA measurement, the newly developed method is not only inexpensive and less laborious, but it also offers improved sensitivity. We believe this novel method will find wide application in identifying the presence of AA in food, herbal medicines, and environmental samples, thus assisting in the identification and removal of AA exposure sources.

MoS2 nanosheets grown on bowl-shaped hollow carbon spheres as an efficient electrochemical sensor for ultrasensitive determination of nephrotoxic aristolochic acids in Chinese traditional herbs.

Aristolochic acid, a substance in herbs, is highly nephrotoxic, so it is crucial to develop an assay that can rapidly and accurately analyze its content. In this study, bowl-shaped hollow carbon spheres (BHCs) were synthesized using a complex template method, and a MoS2 layer was grown in situ on their surface using a hydrothermal method. The synthesized MoS2-BHCs were used to fabricate an electrochemical sensor for the ultrasensitive and highly selective detection of aristolochic acids (AAs). The optimal conditions for AA detection were determined by tailoring the amount of MoS2 used to modify the BHCs and the pH of the electrolyte. Under optimal conditions, the MoS2-BHC-based sensor presented excellent AA detection performance. The linear concentration ranges of the MoS2-BHC-based sensor for the detection of AA were 0.05-10 µmol L-1 and 10-80 µmol L-1, and the limit of detection of the sensor was 14.3 nmol L-1. Moreover, the MoS2-BHC-based sensor detected AA in Aristolochia and Asarum sieboldii samples. The results were consistent with high-performance liquid chromatography data, demonstrating the satisfactory recovery and accuracy of the sensor. Therefore, we believe that MoS2-BHC-based sensors can be used as effective platforms for detecting AA in traditional Chinese herbs.

Rapid identification and detection of aristolochic acids in the herbal extracts by Raman spectroscopy.

Herbs containing aristolochic acids (AAs) have already been proven to be highly carcinogenic and nephrotoxic. In this study, a novel surface-enhanced Raman scattering (SERS) identification method was developed. Ag-APS nanoparticles with a particle size of 3.53 ± 0.92 nm were produced by combining silver nitrate and 3-aminopropylsilatrane. The reaction between the carboxylic acid group of aristolochic acid I (AAI) and amine group of Ag-APS NPs was used to form amide bonds, and thus, concentrate AAI, rendering it easy to detect via SERS and amplified to obtain the best SERS enhancement effect. Detection limit was calculated to be approximately 40 nM. Using the SERS method, AAI was successfully detected in the samples of four Chinese herbal medicines containing AAI. Therefore, this method has a high potential to be applied in the future development of AAI analysis and rapid qualitative and quantitative analysis of AAI in dietary supplements and edible herbs.