Mineral arsenicals in traditional medicines: orpiment, realgar, and arsenolite

Fast pH-Driven Solubilization Method of Realgar (As4S4) to Reduce the Toxicity of Arsenic [As(III)] for Medicinal Purposes

Acute promyelocytic leukemia (APL) accounts for 5-15% of acute myeloid leukemia cases. It is typically characterized by the (15;17) chromosomal translocation, producing the pathogenic retinoic acid receptor (RAR) alpha/promyelocytic leukemia (PML) fusion protein. Recently, remission of APL has been achieved using the first chemotherapy-independent oral drug regimen in anticancer therapy, consisting of all-trans retinoic acid (targeting RARalpha) and the arsenic sulfide realgar (targeting PML). However, clinical adoption of realgar and the characterization of its active breakdown products have been hampered by its poor solubility. Here, a scalable pH/temperature-based process is described that partially mimics gut transition, achieving fast and reproducible solubilization of realgar. Six different spectroscopic and spectrometric techniques are employed to investigate solubilized realgar. Furthermore, it is shown that solubilized realgar targets PML, displaying wider in vitro therapeutic indices and lower off-target effects than arsenic trioxide, the current APL standard of care. Moreover, in line with evidence of an interplay between PML and HIV persistence, solubilized realgar can disrupt HIV latency, the main barrier to an HIV/AIDS cure, in CD4 T cells of people living with HIV. These findings may open avenues for streamlining realgar solubilization and designing less toxic, orally administrable arsenic-based therapies.

Gut microbiota perturbation and subsequent oxidative stress in gut and kidney tissues of zebrafish after individual and combined exposure to inorganic arsenic and fluoride

Chronic exposure to inorganic arsenic (iAs) and fluoride (F) affect gut health and potentially damage organs. The present study investigates the interplay between gut bacteria and oxidative stress (measured by MDA level, GSH level, catalase activity, Nrf2 translocation and expression) in zebrafish exposed to F (NaF 15 ppm) and As (As2O3 50 ppb) alone or in combination. Combined exposure to As and F reduced gut bacterial alteration and imposed less oxidative stress compared to F- exposure alone. V3-V4 metagenomic sequencing revealed Pseudomonas, Aeromonas and Plesiomonas genera dominated in As or F treated groups while As+F treated group was enriched in beneficial Lactococcus and Streptococcus genera. Functional KEGG analysis demonstrated treatment-specific changes in bacterial metabolism, host organismal systems, human diseases, as well as cellular processes of microbial community were significantly affected. When Aeromonas sp. isolated from F-treated fish gut, tagged with GFP-vector and fed (~3.2 × 106 CFU/mL) to untreated fish, induced oxidative stress in gut and kidney. Gut bacteria were found to both increase and mitigate iAs or F-toxicity, whereas As+F treatment promoted a protective response. Correlation analysis between gut microbial community at genus level and oxidative stress parameters of gut and kidney, showed Aeromonas and Plesiomonas genera are strongly correlated with oxidative stress (r = 0.5-0.9, p˂0.05). This study identifies microbiome biomarkers of iAs and F toxicity on gut-kidney axis.

The alleviation effect and its mechanism of Niuhuang Jiedu prescription on realgar-induced genotoxicity in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Realgar (As2S2 or As4S4) is a traditional Chinese medicine (TCM) containing arsenic. Existing studies have shown that it has genotoxicity under long-term use with large doses. Niuhuang Jiedu (NHJD) is a Chinese medicine prescription containing realgar and seven other TCMs. Whether the multiple TCMs combination in NHJD can reduce the genotoxicity induced by realgar in equivalent doses is still unknown.

AIM OF THE STUDY

To research the effect of NHJD on realgar's genotoxicity and the possible mechanism involved based on the arsenic methylation metabolic pathway.

MATERIAL AND METHODS

Six groups (control, realgar (0.8 g/kg), NHJD (12.48 g/kg), as well as Glycyrrhiza uralensis Fisch (GU), Scutellaria baicalensis Georg (SB), Rheum palmatum L (RP) plus equivalent doses of realgar, respectively) were set up. ICR mice were intragastric administered for 12 weeks. First, genotoxicology tests were conducted to evaluate the effect of NHJD, GU, SB, and RP on reducing realgar's genotoxicity. The inorganic arsenic (iAs), dimethyl arsenic acid (DMA), and monomethyl arsenic acid (MMA) were determined by HPLC-AFS, and the iAs%, MMA%, DMA%, primary methylation index (PMI), etc. Were calculated. Meanwhile, the S-adenosyl methionine (SAM) and arsenate reductase (ARR) levels, the arsenic (+3)methyltransferase (As3MT), purine-nucleoside phosphorylase (PNP), glutathione S-transfer omega1 (GSTO1) gene expression were detected, aimed to explore the possible alleviation mechanisms of NHJD.

RESULTS

The combination of multiple TCMs in NHJD decreased the levels of MN‰, SPA%, and DNA damage caused by realgar, with similar effects observed when SB, RP, and GU were used separately with realgar. Notably, the iAs% significantly decreased, while DMA% and PMI notably increased in the NHJD and realgar + SB (or RP) groups compared to the realgar-only group (P < 0.05). Increases in SAM and ARR levels were observed across various groups, but only the ARR increase in the NHJD group was statistically significant. Moreover, significant increases in As3MT mRNA and GSTO1 mRNA were noted in the NHJD group, and PNP mRNA levels significantly rose in the realgar + SB group.

CONCLUSIONS

This study revealed that NHJD could attenuate the genotoxic effects of realgar. The botanicals SB, RP, and GU within NHJD may be key contributors to this effect. Enhancements in arsenic methylation capabilities through increased levels of SAM and ARR and elevated gene expressions of As3MT, PNP, and GSTO1 suggest potential mechanisms behind these findings.

Harness arsenic in medicine: current status of arsenicals and recent advances in drug delivery

INTRODUCTION

Arsenicals have a special place in the history of human health, acting both as poison and medicine. Having been used to treat a variety of diseases in the past, the success of arsenic trioxide (ATO) in treating acute promyelocytic leukemia (APL) in the last century marked its use as a drug in modern medicine. To expand their role against cancer, there have been clinical uses of arsenicals worldwide and progress in the development of drug delivery for various malignancies, especially solid tumors.

AREAS COVERED

In this review, conducted on Google Scholar [1977-2024], we start with various forms of arsenicals, highlighting the well-known ATO. The mechanism of action of arsenicals in cancer therapy is then overviewed. A summary of the research progress in developing new delivery approaches (e.g. polymers, inorganic frameworks, and biomacromolecules) in recent years is provided, addressing the challenges and opportunities in treating various malignant tumors.

EXPERT OPINION

Reducing toxicity and enhancing therapeutic efficacy are guidelines for designing and developing new arsenicals and drug delivery systems. They have shown potential in the fight against cancer and emerging pathogens. New technologies and strategies can help us harness the potency of arsenicals and make better products.

Mineral crude drug mirabilite (Mangxiao) inhibits the occurrence of colorectal cancer by regulating the Lactobacillus-bile acid-intestinal farnesoid X receptor axis based on multiomics integration analysis

Mineral crude drug has revolutionized the treatment landscape in precision oncology niche that leads to the improvement in therapeutic efficiency on various tumor subtypes. Mangxiao (MX), a mineral crude drug in traditional Chinese medicine, has been used for treating gastrointestinal diseases for thousands of years. However, the action mechanisms are still ambiguous. Here, we attempt to explore inhibitory roles and associated pharmacological mechanisms of MX upon colorectal cancer (CRC) in APCMin/+ male mice by integrating metabolomics, 16S rDNA sequencing analyses, and metagenomic-based microbiota analysis. We found that MX can significantly inhibit the occurrence of CRC through the regulation of the dysregulated gut microbe metabolism. Furthermore, the correlation analysis of metabolomes and 16S rDNA revealed that MX could restore the disorders of gut microbes by specifically enriching the abundance of Lactobacilli to improve bile acid metabolism, which further activated the farnesoid X receptor (FXR) in CRC mice, then the improvement of gut dysbiosis could inhibit the development of CRC. Collectively, our effort confirmed MX has the capacity to intervene the development of CRC and further discovered that it targets Lactobacillus-bile acid-intestinal FXR axis, which can be regarded as a candidate medicine for future drug discovery and development against CRC.

Equimolar As4S4/Fe3O4 Nanocomposites Fabricated by Dry and Wet Mechanochemistry: Some Insights on the Magnetic-Fluorescent Functionalization of an Old Drug

Multifunctional nanocomposites from an equimolar As4S4/Fe3O4 cut section have been successfully fabricated from coarse-grained bulky counterparts, employing two-step mechanochemical processing in a high-energy mill operational in dry- and wet-milling modes (in an aqueous solution of Poloxamer 407 acting as a surfactant). As was inferred from the X-ray diffraction analysis, these surfactant-free and surfactant-capped nanocomposites are β-As4S4-bearing nanocrystalline-amorphous substances supplemented by an iso-compositional amorphous phase (a-AsS), both principal constituents (monoclinic β-As4S4 and cubic Fe3O4) being core-shell structured and enriched after wet milling by contamination products (such as nanocrystalline-amorphous zirconia), suppressing their nanocrystalline behavior. The fluorescence and magnetic properties of these nanocomposites are intricate, being tuned by the sizes of the nanoparticles and their interfaces, dependent on storage after nanocomposite fabrication. A specific core-shell arrangement consisted of inner and outer shell interfaces around quantum-confined nm-sized β-As4S4 crystallites hosting a-AsS, and the capping agent is responsible for the blue-cyan fluorescence in as-fabricated Poloxamer capped nanocomposites peaking at ~417 nm and ~442 nm, while fluorescence quenching in one-year-aged nanocomposites is explained in terms of their destroyed core-shell architectures. The magnetic co-functionalization of these nanocomposites is defined by size-extended heterogeneous shells around homogeneous nanocrystalline Fe3O4 cores, composed by an admixture of amorphous phase (a-AsS), nanocrystalline-amorphous zirconia as products of contamination in the wet-milling mode, and surfactant.

Research progress on arsenic, arsenic-containing medicinal materials, and arsenic-containing preparations: clinical application, pharmacological effects, and toxicity

Introduction: The toxicity of arsenic is widely recognized globally, mainly harming human health by polluting water, soil, and food. However, its formulations can also be used for the clinical treatment of diseases such as leukemia and tumors. Arsenic has been used as a drug in China for over 2,400 years, with examples such as the arsenic-containing drug realgar mentioned in Shennong's Herbal Classic. We have reviewed references on arsenic over the past thirty years and found that research has mainly focused on clinical, pharmacological, and toxicological aspects. Results and Discussion: The finding showed that in clinical practice, arsenic trioxide is mainly used in combination with all-trans retinoic acid (ATRA) at a dose of 10 mg/d for the treatment of acute promyelocytic leukemia (APL); realgar can be used to treat acute promyelocytic leukemia, myelodysplastic syndrome, and lymphoma. In terms of pharmacology, arsenic mainly exerts anti-tumor effects. The dosage range of the action is 0.01-80 μmol/L, and the concentration of arsenic in most studies does not exceed 20 μmol/L. The pharmacological effects of realgar include antiviral activity, inhibition of overactivated lactate dehydrogenase, and resistance to malaria parasites. In terms of toxicity, arsenic is toxic to multiple systems in a dose-dependent manner. For example, 5 μmol/L sodium arsenite can induce liver oxidative damage and promote the expression of pro-inflammatory factors, and 15 μmol/L sodium arsenite induces myocardial injury; when the concentration is higher, it is more likely to cause toxic damage.

Study on arsenic speciation, bioaccessibility, and gut microbiota in realgar-containing medicines by DGT technique and artificial gastrointestinal extraction (PBET) combine with simulated human intestinal microbial ecosystem (SHIME)

It is well-known that several Chinese patent medicines use realgar as a specific component. People are more aware of the health dangers associated with realgar since it includes arsenic. Previous research overstated the arsenic toxicity of realgar-containing Chinese prescription medications because little thought was given to the influence of arsenic bioaccessibility by gut microbiota. In light of this, this study examined the total content, bioaccessibility and speciation of targeted medications while also examining intestinal epithelial transit utilizing the diffusive gradients in thin-films (DGT). All samples contained arsenic, and the bioaccessibilities of the colon, intestine and gastric regions ranged from 0.19% to 1.73%, 0.25-1.88% and 0.21-1.70% respectively. The range of DGT-bioaccessibility is 0.01-0.0018%. Three steps of analysis were conducted on inorganic As(III) and As(V). In health risk assessment, the ADDs and HQs of DGT-bioaccessibility were below the threshold levels when compared to computing average daily intake dose (ADD) and hazard quotient (HQ) by bioaccessibility of gastric, intestinal and colon. Additionally, Proteobacteria and Firmicutes were discovered to be the two predominant kinds of gut microbes in this study. Under arsenic exposure, the abundance of Christensenellaceae, Desulfovibrionaceae and Akkermansiaceae increased, but the quantity of Rikenellaceae decreased. These findings revealed that alterations in gut microbiota had an impact on host metabolism.

Traditional Chinese medicine Zhusha Anshen Wan: protective effects on liver, kidney, and intestine of the individual drugs using 1H NMR metabolomics

Introduction: Zhusha Anshen Wan (ZSASW) is a traditional Chinese medicine compound mainly composed of mineral drugs. In clinical practice, ZSASW did not show the toxicity of administering equal doses of cinnabar alone, suggesting that the four combination herbs in ZSASW can alleviate the damage of cinnabar. The effect of each herb on reducing the toxicity of cinnabar has not been fully explained. Methods: In our study, we utilized a metabonomics approach based on high-resolution 1H nuclear magnetic resonance spectroscopy to investigate the reduction of toxicity by each herb in ZSASW. Liver, kidney and intestinal histopathology examinations and biochemical analysis of the serum were also performed. Results: Partial least squares-discriminant analysis (PLS-DA) was conducted to distinct different metabolic profiles in the urine and serum from the rats. Liver and kidney histopathology examinations, as well as analysis of serum clinical chemistry analysis, were also carried out. The metabolic profiles of the urine and serum of the rats in the CGU (treated with cinnabar and Glycyrrhiza uralensis Fisch) and CCC (treated with cinnabar and Coptis chinensis French) groups were remarkably similar to those of the control group, while those of the CRG (treated with cinnabar and Rehmannia glutinosa Libosch) and CAS (treated with cinnabar and Angelica sinensis) groups were close to those of the cinnabar group. The metabolic profiles of the urine and serum of the rats in the CGU and CCC groups were remarkably similar to those of the control group, while those of the CRG and CAS groups were close to those of the cinnabar group. Changes in endogenous metabolites associated with toxicity were identified. Rehmannia glutinosa, Rhizoma Coptidis and Glycyrrhiza uralensis Fisch could maintain the dynamic balance of the intestinal flora. These results were also verified by liver, kidney and intestinal histopathology examinations and biochemical analysis of the serum. The results suggested that Discussion: The metabolic mechanism of single drug detoxification in compound prescriptions has been elucidated. Coptis chinensis and Glycyrrhiza uralensis serve as the primary detoxification agents within ZSASW for mitigating liver, kidney, and intestinal damage caused by cinnabar. Detoxification can be observed through changes in the levels of various endogenous metabolites and related metabolic pathways.

Animal-and mineral-based medicines in Gansu-Ningxia-inner Mongolia region, P.R. China: a cross-cultural ethnobiological assessment

Introduction: Traditional animal- and mineral-based medicines are widely used in the Gansu-Ningxia-Inner Mongolia junction zone, a region with diverse ethnic groups and cultures. This study aims to document, conserve, and explore the potential of these medicines for further research and sustainable development of ethnic medicine. Methods: We interviewed 56 informants from different ethnic backgrounds and analyzed their responses quantitatively. Additionally, a comparative analysis with adjacent regions was conducted, providing invaluable contextual insights. Results: The study unveiled a diverse array of traditional medicines in the Gansu-Ningxia-Inner Mongolia junction zone. A total of 47 animal-based medicines were identified, ranging from insects and scorpios to distinctive animal organs. Of notable significance was Moschus, emerging as a pivotal traditional Chinese medicine resource. In parallel, 12 mineral-based medicines were cataloged, procured both locally and from "pharmacies". Female informants, frequently local herbal practitioners, demonstrated broader knowledge of medicines. The analysis of 13 villages revealed varying perceptions of medicine importance, underscoring the wealth of traditional knowledge. Specific medicines, such as Feng-Mi and Xie-Zi, were widely used and valued in local healthcare practices for their cultural and medicinal benefits. Conclusion: This study provides a comprehensive overview of traditional animal- and mineral-based medicines in the Gansu-Ningxia-Inner Mongolia junction zone. It highlights the need for preserving and applying these practices in a sustainable manner. It also lays a solid foundation for future research on ethnic medicine, which can contribute to the holistic wellbeing of local communities.

Low-intensity ultrasound combined with arsenic trioxide induced apoptosis of glioma via EGFR/AKT/mTOR

AIMS

This study aimed to explore whether low-intensity ultrasound (LIUS) combined with low-concentration arsenic trioxide (ATO) could inhibit the proliferation of glioma and, if so, to clarify the potential mechanism.

MAIN METHODS

The effects of ATO and LIUS alone or in combination on glioma were examined by CCK8, EdU, and flow cytometry assays. Western blot analysis was used to detect changes in expression of apoptosis-related proteins and their effects on the EGFR/AKT/mTOR pathway. The effects of ATO and LIUS were verified in vivo in orthotopic xenograft models, and tumor size, arsenic content in brain tissue, survival, and immunohistochemical changes were observed.

KEY FINDINGS

LIUS enhanced the inhibitory effect of ATO on the proliferation of glioma, and EGF reversed the proliferation inhibition and protein changes induced by ATO and LIUS. The anti-glioma effect of ATO combined with LIUS was related to downstream AKT/mTOR pathway changes caused by inhibition of EGFR activation, which enhanced apoptosis of U87MG and U373 cells. In vivo experiments showed significant increases in arsenic content in brain tissue, as well as decreased tumor sizes and longer survival times in the combined treatment group compared with other groups. The trends of immunohistochemical protein changes were consistent with the in vitro results.

SIGNIFICANCE

This study showed that LIUS enables ATO to exert anti-glioma effects at a safe dose by inhibiting the activation of EGFR and the downstream AKT/mTOR pathway to regulate apoptosis. LIUS in combination with ATO is a promising novel method for treating glioma and could improve patient prognosis.

Assessment of sub-chronic oral toxicity of Nityanand Rasa: An ayurvedic herbo-metallic formulation

ETHNOPHARMACOLOGICAL RELEVANCE

Nityananda Rasa (NR) is an ayurvedic herbo-metallic formulation used to treat gout, obesity, hypothyroidism, elephantiasis, and other diseases. However, its safety is a concern owing to the use of heavy metals like mercury and arsenic.

AIM OF THE STUDY

To study the sub-chronic oral toxicity of NR on albino wistar rats for safety evaluation.

MATERIALS AND METHODS

The male and female albino wistar rats were administered a daily dose of 30 (low), 300 (medium) and 600 (high) mg/kg BW/day of NR for 90-day period. The body weight and feed consumption were monitored once a week. After 90 days, blood and vital organs were harvested for genotoxicity, hematology, biochemistry, histopathology, gene expression and the biodistribution analysis.

RESULTS

There was no mortality or severe behavioural changes observed in rats. Significant changes in biochemical enzyme levels were seen at medium and high doses of NR i. e. 300 and 600 mg/kg BW/day respectively. No hematological changes were observed. Mild histopathological changes seen at high dose of NR which were found in concurrence with the biochemical alterations in liver and brain. There was mild genotoxicity and no detectable level of mercury but significant arsenic level in blood at high dose. Gene expression was mildly affected.

CONCLUSIONS

NR induced moderate toxic effects at high dose but can be considered safe at therapeutic doses.

Analytical insights into the detoxification process and characterization of a traditional metallopharmaceutical formulation

Metallopharmaceuticals possess unique medicinal properties and have been used since ancient times. In spite of the inclusion of several metals and minerals, there is an increased interest in metallo-drugs for clinical and research purposes because of their immense therapeutic efficiency and non-toxic claim, as they are processed in addition to specific poly herbals. Sivanar Amirtham is one of the traditional metallopharmaceuticals used in Siddha medicine to treat various respiratory diseases and other ailments, including antidote therapy for poisonous bites. The present research work attempted to formulate the metallodrug preparation as per the standard protocols, including the detoxification process of the raw materials, followed by the analytical characterization studies to evaluate the physicochemical properties responsible for the stability, quality, and efficacy. The study included the comparative analysis of the raw materials, processed samples, intermediate samples, finished products, and commercial samples to understand the science involved in detoxification and formulation processing. The appropriate product profile was developed based on analysis of the particle size and surface charge by Zeta sizer, morphology and distribution by SEM-EDAX, functional groups and chemical interactions by FTIR, thermal behavior and stability by TG-DSC, crystallinity by XRD, and elemental composition by XPS. The findings of the research could provide scientific proof of evidence to overcome the limitations of the product owing to the standard quality and safety concern of the metal-mineral constituents, such as mercury, sulphur, and arsenic in the polyherbomineral formulation.

Microplastics affect arsenic bioavailability by altering gut microbiota and metabolites in a mouse model

Microplastics exposure is a new human health crisis. Although progress in understanding health effects of microplastic exposure has been made, microplastic impacts on absorption of co-exposure toxic pollutants such as arsenic (As), i.e., oral bioavailability, remain unclear. Microplastic ingestion may interfere As biotransformation, gut microbiota, and/or gut metabolites, thereby affecting As oral bioavailability. Here, mice were exposed to arsenate (6 μg As g^-1) alone and in combination with polyethylene particles of 30 and 200 μm (PE-30 and PE-200 having surface area of 2.17 × 10³ and 3.23 × 10² cm² g^-1) in diet (2, 20, and 200 μg PE g^-1) to determine the influence of microplastic co-ingestion on arsenic (As) oral bioavailability. By determining the percentage of cumulative As consumption recovered in urine of mice, As oral bioavailability increased significantly (P < 0.05) from 72.0 ± 5.41% to 89.7 ± 6.33% with PE-30 at 200 μg PE g^-1 rather than with PE-200 at 2, 20, and 200 μg PE g^-1 (58.5 ± 19.0%, 72.3 ± 6.28%, and 69.2 ± 17.8%). Both PE-30 and PE-200 exerted limited effects on pre- and post-absorption As biotransformation in intestinal content, intestine tissue, feces, and urine. They affected gut microbiota dose-dependently, with lower exposure concentrations having more pronounced effects. Consistent with the PE-30-specific As oral bioavailability increase, PE exposure significantly up-regulated gut metabolite expression, and PE-30 exerted greater effects than PE-200, suggesting that gut metabolite changes may contribute to As oral bioavailability increase. This was supported by 1.58-4.07-fold higher As solubility in the presence of up-regulated metabolites (e.g., amino acid derivatives, organic acids, and pyrimidines and purines) in the intestinal tract assessed by an in vitro assay. Our results suggested that microplastic exposure especially smaller particles may exacerbate the oral bioavailability of As, providing a new angle to understand health effects of microplastics.

Arsenic in medicine: past, present and future

Arsenicals are one of the oldest treatments for a variety of human disorders. Although infamous for its toxicity, arsenic is paradoxically a therapeutic agent that has been used since ancient times for the treatment of multiple diseases. The use of most arsenic-based drugs was abandoned with the discovery of antibiotics in the 1940s, but a few remained in use such as those for the treatment of trypanosomiasis. In the 1970s, arsenic trioxide, the active ingredient in a traditional Chinese medicine, was shown to produce dramatic remission of acute promyelocytic leukemia similar to the effect of all-trans retinoic acid. Since then, there has been a renewed interest in the clinical use of arsenicals. Here the ancient and modern medicinal uses of inorganic and organic arsenicals are reviewed. Included are antimicrobial, antiviral, antiparasitic and anticancer applications. In the face of increasing antibiotic resistance and the emergence of deadly pathogens such as the severe acute respiratory syndrome coronavirus 2, we propose revisiting arsenicals with proven efficacy to combat emerging pathogens. Current advances in science and technology can be employed to design newer arsenical drugs with high therapeutic index. These novel arsenicals can be used in combination with existing drugs or serve as valuable alternatives in the fight against cancer and emerging pathogens. The discovery of the pentavalent arsenic-containing antibiotic arsinothricin, which is effective against multidrug-resistant pathogens, illustrates the future potential of this new class of organoarsenical antibiotics.

Transient Glycolytic Complexation of Arsenate Enhances Resistance in the Enteropathogen Vibrio cholerae

The ubiquitous presence of toxic arsenate (As^V) in the environment has raised mechanisms of resistance in all living organisms. Generally, bacterial detoxification of As^V relies on its reduction to arsenite (As^III) by ArsC, followed by the export of As^III by ArsB. However, how pathogenic species resist this metalloid remains largely unknown. Here, we found that Vibrio cholerae, the etiologic agent of the diarrheal disease cholera, outcompetes other enteropathogens when grown on millimolar concentrations of As^V. To do so, V. cholerae uses, instead of ArsCB, the As^V-inducible vc1068-1071 operon (renamed var for vibrio arsenate resistance), which encodes the arsenate repressor ArsR, an alternative glyceraldehyde-3-phosphate dehydrogenase, a putative phosphatase, and the As^V transporter ArsJ. In addition to Var, V. cholerae induces oxidative stress-related systems to counter reactive oxygen species (ROS) production caused by intracellular As^V. Characterization of the var mutants suggested that these proteins function independently from one another and play critical roles in preventing deleterious effects on the cell membrane potential and growth derived from the accumulation As^V. Mechanistically, we demonstrate that V. cholerae complexes As^V with the glycolytic intermediate 3-phosphoglycerate into 1-arseno-3-phosphoglycerate (1As3PG). We further show that 1As3PG is not transported outside the cell; instead, it is subsequently dissociated to enable extrusion of free As^V through ArsJ. Collectively, we propose the formation of 1As3PG as a transient metabolic storage of As^V to curb the noxious effect of free As^V. This study advances our understanding of As^V resistance in bacteria and underscores new points of vulnerability that might be an attractive target for antimicrobial interventions. IMPORTANCE Even though resistance to arsenate has been extensively investigated in environmental bacteria, how enteric pathogens tolerate this toxic compound remains unknown. Here, we found that the cholera pathogen V. cholerae exhibits increased resistance to arsenate compared to closely related enteric pathogens. Such resistance is promoted not by ArsC-dependent reduction of arsenate to arsenite but by an operon encoding an arsenate transporter (ArsJ), an alternative glyceraldehyde 3-phosphate dehydrogenase (VarG), and a putative, uncharacterized phosphatase (VarH). Mechanistically, we demonstrate that V. cholerae detoxifies arsenate by complexing it with the glycolytic intermediate 3-phosphoglycerate into 1-arseno-3-phosphoglycerate (1As3PG). 1As3PG is not transported outside the cell; instead, it is subsequently dissociated by VarH to enable extrusion of free arsenate through ArsJ. Collectively, this study proposes a novel mechanism for arsenate detoxification, entirely independent of arsenate reduction and arsenite extrusion, that enhances V. cholerae resistance to this metalloid compared to other enteric pathogens.

Realgar (As4S4), a traditional Chinese medicine, induces acute promyelocytic leukemia cell death via the Bcl-2/Bax/Cyt-C/AIF signaling pathway in vitro

Acute promyelocytic leukemia (APL) is a specific subtype of acute myelogenous leukemia (AML) characterized by the proliferation of abnormal promyelocytes. Realgar, a Chinese medicine containing arsenic, can be taken orally. Traditional Chinese medicine physicians have employed realgar to treat APL for over a thousand years. Therefore, realgar may be a promising candidate for the treatment of APL. Nevertheless, the underlying mechanism behind realgar therapy is largely unclear. The present study aimed to investigate the effect of realgar on cell death in the APL cell line (NB4) in vitro and to elucidate the underlying mechanism. In this study, after APL cells were treated with different concentrations of realgar, the cell survival rate, apoptotic assay, morphological changes, ATP levels and cell cycle arrest were assessed. The expression of Bcl-2, Bax, Cytochrome C (Cyt-C) and apoptosis-inducing factor (AIF) at the mRNA and protein levels were also measured by immunofluorescence, quantitative PCR (qPCR) and Western blotting. We found that realgar could significantly inhibit APL cell proliferation and cell death in a time- and dose-dependent manner. Realgar effectively decreased the ATP levels in APL cells. Realgar also induced APL cell cycle arrest at the S and G2/M phases. Following realgar treatment, the mRNA and protein levels of Bcl-2 were significantly downregulated, whereas the levels of Bax, Cyt-C, and AIF were significantly upregulated. In summary, realgar can induce APL cell death via the Bcl-2/Bax/Cyt-C/AIF signaling pathway, suggesting that realgar may be an effective therapeutic for APL.

Arsenic Toxicity on Metabolism and Autophagy in Adipose and Muscle Tissues

Arsenic, a naturally occurring metalloid derived from the environment, has been studied worldwide for its causative effects in various cancers. However, the effects of arsenic toxicity on the development and progression of metabolic syndrome, including obesity and diabetes, has received less attention. Many studies suggest that metabolic dysfunction and autophagy dysregulation of adipose and muscle tissues are closely related to the development of metabolic disease. In the USA, arsenic contamination has been reported in some ground water, soil and grain samples in major agricultural regions, but the effects on adipose and muscle tissue metabolism and autophagy have not been investigated much. Here, we highlight arsenic toxicity according to the species, dose and exposure time and the effects on adipose and muscle tissue metabolism and autophagy. Historically, arsenic was used as both a poison and medicine, depending on the dose and treatment time. In the modern era, arsenic intoxication has significantly increased due to exposure from water, soil and food, which could be a contributing factor in the development and progression of metabolic disease. From this review, a better understanding of the pathogenic mechanisms by which arsenic alters metabolism and autophagy regulation could become a cornerstone leading to the development of therapeutic strategies against arsenic-induced toxicity and metabolic disease.

Pigmented Remedies: The Pharmacy of Colour in Early Modern Europe

This article will examine pigments recently identified in an unpublished conservation survey at the Wellcome Collection that included two 17^th-century medical manuscripts. These pigments, which were drawn from plant and mineral products, served a dual purpose based on their medicinal and pigmented properties. An exploration of how these pigments were used (and why) by a range of practitioners - including apothecaries, physicians, "kitchen physicians," and artisans - reveals the importance of colour throughout early modern Europe. The persistence of traditional medical theories is revealed by examining evidence across an extensive period covering the 16^th to the 18^th century. Receipt books, medical treatises, and health guides are contrasted with artisanal texts reflecting the blurring of boundaries between the worlds of medicine and art. Modern analysis by conservators of colour used in medieval and early modern texts is crucial to the preservation of pigments but also provides a deeper understanding of what and how pigmented products were used in the period and, ultimately, informs our current understandings of early modern life and medicine.

Arsenic and antimony co-contamination influences on soil microbial community composition and functions: Relevance to arsenic resistance and carbon, nitrogen, and sulfur cycling

Microorganisms can mediate arsenic (As) and antimony (Sb) transformation and thus change the As and Sb toxicity and mobility. The influence of As and Sb on the innate microbiome has been extensively characterized. However, how microbial metabolic potentials are influenced by the As and Sb co-contamination is still ambiguous. In this study, we selected two contrasting sites located in the Shimen realgar mine, the largest realgar mine in Asia, to explore the adaptability and response of the soil microbiome to As and Sb co-contamination and the impact of co-contamination on microbial metabolic potentials. It is observed that the geochemical parameters, including the As and Sb fractions, were the driving forces that reshaped the community composition and metabolic potentials. Bacteria associated with Bradyrhizobium, Nocardioides, Sphingomonas, Burkholderia, and Streptomyces were predicted to be tolerant to high concentrations of As and Sb. Co-occurrence network analysis revealed that the genes related to C fixation, nitrate/nitrite reduction, N fixation, and sulfate reduction were positively correlated with the As and Sb fractions, suggesting that As and Sb biogeochemical cycling may interact with and benefit from C, N, and S cycling. The results suggest that As and Sb co-contamination not only influences As-related genes, but also influences other genes correlated with microbial C, N, and S cycling.

Hypoxia enhances the cytotoxic effect of As4S4 on rat ventricular H9c2 cells through activation of ubiquitin-proteasome system

BACKGROUND

As₄S₄ is widely used in Chinese traditional medicine compound. However, based on some recent studies, we found that the cardiotoxicity risk of using As₄S₄ in ischemic heart disease patients may be increased. To study this potential risk, we compared the effects of As₄S₄ on rat ventricular H9c2 cell line with or without hypoxic pretreatment, and to elucidate mechanisms of c-Cbl mediated ubiquitination/degradation of integrin β1.

METHODS

The present study was conducted on rat ventricular H9c2 cell line in the absence or presence of hypoxic pretreatment for 6 h followed by As₄S₄ treatment for 24 h. Following As₄S₄ treatment, cell viability assay, flow cytometric quantification of apoptotic cells, caspase-3 activity assay and DAPI staining were conducted. Western blotting was carried out to detect expressions of ubiquitination related proteins. In addition, the ubiquitination/degradation of integrin β1 and the role of c-Cbl in it was evaluated by immunoprecipitation and immunoblot assay.

RESULTS

The viability of cells with hypoxic pretreatment followed by As₄S₄ treatment was decreased significantly, apoptosis rate and the activity of caspase-3 were increased than As₄S₄ treatment alone. The ubiquitin-proteasome degradation pathway induced by As₄S₄ was further enhanced by hypoxic pretreatment. The results of IP and immunoblot assay showed hypoxic enhanced down-regulation effect of As₄S₄ on integrin β1 probably through c-Cbl activation.

CONCLUSIONS

This study demonstrated that the hypoxia enhanced cytotoxicity of As₄S₄ on H9c2 cells may through increasing the ubiquitin-proteasome degradation of integrin β1 mediated by the E3 ligase c-Cbl. The results provide an important clue that, in patients with ischemic heart disease, use of As₄S₄ may be associated with increased cardiotoxicity. We believe that the results worth to be further illuminated by in vivo and clinical research.

Arsenic compounds: The wide application and mechanisms applied in acute promyelocytic leukemia and carcinogenic toxicology

Arsenic (As), as well as its various compounds have been widely used for nearly 4000 years either as drugs or poisons. These compounds are valuable in the treatment of various diseases ranging from dermatosis to cancer, thereby emphasizing their important roles as therapeutic agents. The ability of As compounds, especially arsenic trioxide (ATO) in the treatment of acute promyelocytic leukemia (APL), has fundamentally altered people's understanding of the poison, and has become a major factor in the re-emergence of Western medicine candidates to treat leukemia and other solid tumors. However, long-term exposure to As has been correlated with numerous disadvantageous influences on health, particularly carcinogenesis. Importantly, accumulating evidence suggests that biotransformation of As, as a step to eliminate As from the human body, can induce alterations at the genetic and epigenetic levels, resulting in therapeutic effects or carcinogenesis. In this article, we aimed to provide a systematic overview of the primary contributions associated with As and its compounds, as well as the detailed mechanisms applied in APL cells and carcinogenic toxicology. This review may help to understand the underlying mechanisms and safe wide clinical applications of medicinal As along with its compounds.

A Single Microbiome Gene Alters Murine Susceptibility to Acute Arsenic Exposure

Environmental toxicant exposure contributes to morbidity and mortality of many human diseases. With respect to arsenic, microbially driven chemical transformations dictate its toxicity and mobility in virtually every environment yet studied, so a general hypothesis is that the human gut microbiome determines disease outcome following exposure. However, the complex nature of the gut microbiome and the myriad of potential interactions with human cells/tissues make it challenging to quantify the influence of specific arsenic-active functions-a requisite step in developing effective disease prevention and/or clinical intervention strategies. To control both mammalian and microbial function during toxicant exposure, we genetically defined the gut microbiome of mice using only Escherichia coli strain, AW3110 (▵arsRBC), or the same strain carrying a single genome copy of the Fucus vesiculosus metallothionein gene (AW3110::fmt); a cysteine-rich peptide that complexes with arsenite, facilitating bioaccumulation and reducing its toxic effects. AW3110::fmt bioaccumulated significantly more arsenic and gnotobiotic mice colonized by this strain excreted significantly more arsenic in stool and accumulated significantly less arsenic in organs. Moreover, AW3110::fmt gnotobiotic mice were protected from acute toxicity exposure (20 ppm AsIII) relative to controls. This study demonstrates-in a highly controlled fashion-that a single microbiome function (arsenic bioaccumulation) encoded by a single gene in a single human gut microbiome bacterium significantly alters mammalian host arsenic exposure. The experimental model described herein allows for a highly controlled and directed assessment of microbiome functions, and is useful to quantify the influence of specific microbiome-arsenic interactions that help mitigate human disease.

Combined effect of arsenic and fluoride at environmentally relevant concentrations in zebrafish (Danio rerio) brain: Alterations in stress marker and apoptotic gene expression

Arsenic and fluoride are two naturally occurring toxicants to which various organisms including a major part of the human populations are co-exposed to. However, interactions between them inside body are quite complicated and needs proper evaluation. Inconclusive reports regarding their combined effects on brain prompted us to conduct this study where we investigated their individual as well as combined effects on female zebrafish brain at environmentally relevant concentrations (50 μgL^-1 arsenic trioxide and 15 mgL^-1 sodium fluoride) after different time intervals (15, 30 and 60 days). Persistent near-basal level of GSH, least increased MDA content and catalase activity portrayed arsenic and fluoride co-exposure as less toxic which was corroborated with far less damage caused in the histoarchitecture of optic tectum region in midbrain. Stress-responsive genes viz., Nrf2 and Hsp70 were overexpressed after individual as well as combined exposures, indicating a common cellular response to combat the formed oxidative stresses. Biphasic response of AChE upon individual exposure confirmed their neurotoxic effects too. Expression profile of p53 (unaltered), Bax (lower or near-basal) and Bcl2 (comparatively higher), along with absence of DNA fragmentation indicated no induction of apoptosis in the co-exposed group. Tissue accumulation of arsenic and fluoride was significantly less in the brain of co-exposed zebrafish when compared to their individual exposures. This preliminary study indicates an antagonistic effect of these two toxicants in zebrafish brain and needs further studies involving oxidative stress independent markers to understand the detailed molecular mechanism.

Realgar increases defenses against infection by Enterococcus faecalis in Caenorhabditis elegans

ETHNOPHARMACOLOGICAL RELEVANCE

Realgar has been used in traditional remedies for a long history in China and India. It is clinically used to treat diverse cancers, especially acute promyelocytic leukemia (APL), chronic myelogenous leukemia (CML) in China. However, paradoxic roles of realgar to increase or decrease immunity are reported. It is urgent to address this question, due to immune depression can be strongly benefit to cancer development, but detrimental to patients.

AIM OF THE STUDY

This present work is to explore whether realgar promote or suppress immune responses, and shed light on its mode of action. Our results should provide cues for rational strategy to explore realgar for clinical use.

MATERIAL AND METHODS

Infection model in vivo was established by using Enterococcus faecalis to attack Caenorhabditis elegans, then realgar was used to treat the infected worms to investigate its effects on infectivity and the underlying mechanism. Killing analysis was carried out to test whether realgar can mitigate worm infection. Thermotolerance resistance analysis was used to evaluate if realgar functions hormetic effect. Quantification of live E. faecalis in nematode intestine was employed to ascertain if realgar alleviate the bacterial load in worm gut. Quantitative real-time PCR (qRT-PCR) was used to test the expression of antibacterial effectors. Western blot was used to test the effect of realgar on the expressions of p38 and phospho-p38 in worms infected by E. faecalis.

RESULTS

Realgar alleviated the infected worms in strains of N2, glp-4, and daf-2, but failed in sek-1, glp-4; sek-1, and daf-2; daf-16 when p38 MAPK or daf-16 was blocked or inactivated. Western blot assay demonstrated that realgar increased the expression of phosph-p38. Thermotolerance assay showed that realgar played a hormetic role on nemtodes, triggered protective response and reduced bacterial load after realgar treatment for 120 h qRT-PCR demonstrated that realgar significantly increased antibacterial effectors, thus leading to pathogen elimination.

CONCLUSION

Realgar increased defenses against E. faecalis in C. elegans by inducing both immune responses and protective responses. It was regulated by p38 MAPK pathway and DAF-16.

Arsenate phytotoxicity regulation by humic acid and related metabolic mechanisms

The use of irrigation water containing arsenic (As) had led to large areas of As-contaminated farmland, and as a result, plants and food have become severely poisoned. Humic acid (HA) can be complexed with metals, which in turn affects the metals' behavior. Herein, we explored the accumulation of arsenate in lettuce treated with different concentrations of arsenate and studied the effects of HA on the accumulation and toxicity of arsenate. The addition of HA did not cause significant changes in the arsenate content in lettuce but had a significant effect on the activity of antioxidant enzymes, which improved the antioxidant capability of the lettuce plants. Furthermore, HA promoted the accumulation of nutrients, such as magnesium (Mg), calcium (Ca), molybdenum (Mo) and manganese (Mn), in the leaves. Arsenate disrupted metabolic pathways, such as amino acid metabolism, carbohydrate metabolism, and aminoacyl-tRNA biosynthesis. The addition of HA increased the contents of amino acids and sugars, thereby improving lettuce growth. The present study explored the effects of HA on As accumulation and related physiological changes (antioxidant enzyme activities, absorption of nutrients and metabolic mechanisms) and provided insights into the regulation of As contamination by HA, which is relatively inexpensive.

Involvement of autophagy in realgar quantum dots (RQDs) inhibition of human endometrial cancer JEC cells

Realgar (As₄S₄) has been used in traditional Chinese medicines for treatment of malignancies. The poor solubility of As₄S₄ hampered its clinical applications. Realgar quantum dots (RQDs) were developed to overcome these problems. Previous studies revealed that the RQDs were effective against endometrial cancer JEC cells and hepatocarcinoma HepG2 cells via inducing apoptosis.Apoptosis and autophagy are important programmed cell death pathways leading to anticancer effects. This study further examined effects of RQDs on autophagy, focusing on the formation of the autophagosome in JEC cells. CCK8 assay was used to examine cell proliferation. Flow cytometry was used to analyze cell cycle. Transmission electron microscopy (TEM) was used to examine the autophagy, cells were transfected with pEGFP-C3-MAP1LC3B plasmid to examine effects of RQDs on autophagosome via confocal microscope. Autophagy-related proteins were examined by Western blot. RQDs exhibited cytotoxicity in JEC cells in a concentration- and time- dependent manner. RQDs induced G2 and S phase arrest in JEC cells. RQDs significantly induced autophagy, with the double-membrane and autophagosome-like structures by TEM. The diffused distribution of pEGFP-C3-MAP1LC3B green fluorescence were become the punctuate pattern fluorescence after treatment with RQDs in cells transfected with pEGFP-C3-MAP1LC3B plasmid RQDs increased the expression of autophagyregulatory proteins LC3 I/II, Beclin-1, p62 and Atg12 in a concentration-dependent manner, similar to autophagy induced by serum starvation, except for p62, as induction of p62 is a characteristic of arsenic compounds. Taken together, the present study clearly demonstrated that RQDs can induce autophagy in JEC cells as one of mechanisms of anticancer effects, and indicated that RQDs may be developed as an autophagy inducer.

Realgar Nanoparticles Inhibit Migration, Invasion and Metastasis in a Mouse Model of Breast Cancer by Suppressing Matrix Metalloproteinases and Angiogenesis

BACKGROUND

Realgar, a traditional Chinese medicine, has shown antitumor efficacy in several tumor types. We previously showed that realgar nanoparticles (nano-realgar) had significant antileukemia, anti-lung cancer and anti-liver cancer effects. In addition, the anti-tumor effects of nanorealgar were significantly better than those of ordinary realgar.

OBJECTIVE

To explore the inhibitory effects and molecular mechanisms of nano-realgar on the migration, invasion and metastasis of mouse breast cancer cells.

METHODS

Wound-healing migration assays and Transwell invasion assays were carried out to determine the effects of nano-realgar on breast cancer cell (4T1) migration and invasion. The expression levels of matrix metalloproteinase (MMP)-2 and -9 were measured by Western blot. A murine breast cancer metastasis model was established, administered nano-realgar for 32 days and monitored for tumor growth and metastasis by an in vivo optical imaging system. Finally, living imaging and hematoxylin and eosin (HE) staining were used to measure the morphology and pathology of lung and liver cancer cell metastases, respectively. Angiogenesis was assessed by CD34 immunohistochemistry.

RESULTS

Nano-realgar significantly inhibited the migration and invasion of breast cancer 4T1 cells and the expression of MMP-2 and -9. Meanwhile, nano-realgar effectively suppressed the abilities of tumor growth, metastasis and angiogenesis in the murine breast cancer metastasis model in a time- and dosedependent manner.

CONCLUSION

Nano-realgar significantly inhibited migration and invasion of mouse breast cancer cells in vitro as well as pulmonary and hepatic metastasis in vivo, which may be closely correlated with the downexpression of MMP-2 and -9 and suppression of tumor neovascularization.

Mechanisms underlying the protective effect of tannic acid against arsenic trioxide‑induced cardiotoxicity in rats: Potential involvement of mitochondrial apoptosis

Arsenic trioxide (ATO) is a frontline chemotherapy drug used in the therapy of acute promyelocytic leukemia. However, the clinical use of ATO is hindered by its cardiotoxicity. The present study aimed to observe the potential effects and underlying mechanisms of tannic acid (TA) against ATO-induced cardiotoxicity. Male rats were intraperitoneally injected with ATO (5 mg/kg/day) to induce cardiotoxicity. TA (20 and 40 mg/kg/day) was administered to evaluate its cardioprotective efficacy against ATO-induced heart injury in rats. Administration of ATO resulted in pathological damage in the heart and increased oxidative stress as well as levels of serum cardiac biomarkers creatine kinase and lactate dehydrogenase and the inflammatory marker NF-κB (p65). Conversely, TA markedly reversed this phenomenon. Additionally, TA treatment caused a notable decrease in the expression levels of cleaved caspase-3/caspase-3, Bax, p53 and Bad, while increasing Bcl-2 expression levels. Notably, the application of TA decreased the expression levels of cytochrome c, second mitochondria-derived activator of caspases and high-temperature requirement A2, which are apoptosis mitochondrial-associated proteins. The present findings indicated that TA protected against ATO-induced cardiotoxicity, which may be associated with oxidative stress, inflammation and mitochondrial apoptosis.

Arsenic trioxide as a novel anti-glioma drug: a review

Arsenic trioxide has shown a strong anti-tumor effect with little toxicity when used in the treatment of acute promyelocytic leukemia (APL). An effect on glioma has also been shown. Its mechanisms include regulation of apoptosis and autophagy; promotion of the intracellular production of reactive oxygen species, causing oxidative damage; and inhibition of tumor stem cells. However, glioma cells and tissues from other sources show different responses to arsenic trioxide. Researchers are working to enhance its efficacy in anti-glioma treatments and reducing any adverse reactions. Here, we review recent research on the efficacy and mechanisms of action of arsenic trioxide in the treatment of gliomas to provide guidance for future studies.

Liver metabonomics study on the protective effect of glycyrrhetinic acid against realgar-induced liver injury

Glycyrrhetinic acid (GA) is the bioactive ingredient in Glycyrrhizae Radix et Rhizoma. Our previous study has reported that GA has protective effect on realgar-induced hepatotoxicity. However, the details of the hepatoprotective mechanisms of GA on realgar-induced liver injury remain to be elucidated. In the study, mice were divided into control, GA-control, realgar, and co-treated groups. Their liver tissues were used for metabonomics study by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) method. The results illustrate that GA significantly ameliorate the liver injury and metabolic perturbations caused by realgar. Some metabolites, such as phenylalanine, pyroglutamic acid (PGA), proline, carnitine, nicotinamide, choline, lysophosphatidylcholine (LPC) 16 : 0 and LPC 18 : 2 were found responsible for the hepatoprotective effect of GA. These metabolites are associated with the methylation metabolism of arsenic, cell membrane structure, energy metabolism and oxidative stress. From the results of this study, we infer that the potential hepatoprotective mechanism of GA on realgar-induced liver injury may be associated with reducing arsenic accumulation and its methylation metabolism in the liver, promoting the conjugation of arsenic and GSH to play detoxification effect, and ameliorating the liver metabolic perturbations caused by realgar.

Organoarsenicals inhibit bacterial peptidoglycan biosynthesis by targeting the essential enzyme MurA

Trivalent organoarsenicals such as methylarsenite (MAs(III)) are considerably more toxic than inorganic arsenate (As(V)) or arsenite (As(III)). In microbial communities MAs(III) exhibits significant antimicrobial activity. Although MAs(III) and other organoarsenicals contribute to the global arsenic biogeocycle, how they exert antibiotic-like properties is largely unknown. To identify possible targets of MAs(III), a genomic library of the gram-negative bacterium, Shewanella putrefaciens 200, was expressed in Escherichia coli with selection for MAs(III) resistance. One clone contained the S. putrefaciens murA gene (SpmurA), which catalyzes the first committed step in peptidoglycan biosynthesis. Overexpression of SpmurA conferred MAs(III) resistance to E. coli. Purified SpMurA was inhibited by MAs(III), phenylarsenite (PhAs(III)) or the phosphonate antibiotic fosfomycin but not by inorganic As(III). Fosfomycin inhibits MurA by binding to a conserved residue that corresponds to Cys117 in SpMurA. A C117D mutant was resistant to fosfomycin but remained sensitive to MAs(III), indicating that the two compounds have different mechanisms of action. New inhibitors of peptidoglycan biosynthesis are highly sought after as antimicrobial drugs, and organoarsenicals represent a new area for the development of novel compounds for combating the threat of antibiotic resistance.

Arsenic induced epigenetic changes and relevance to treatment of acute promyelocytic leukemia and beyond

Epigenetic alterations regulate gene expression without changes in the DNA sequence. It is well-demonstrated that aberrant epigenetic changes contribute to the leukemogenesis of acute promyelocytic leukemia (APL). Arsenic trioxide (ATO) is one of the most common drugs used in the frontline treatment of APL that act through targeting and destabilizing the PML/RARα oncofusion protein. ATO together with all-trans retinoic acid (ATRA) lead to durable remission of more than 90% non-high-risk APL patients, turning APL treatment into a paradigm of oncoprotein targeted cure. Although relapse and drug resistance in APL are yet to be resolved in the clinic, epigenetic machineries might hold the key to address this issue. Further, ATO also showed promising anticancer activities against a variety of malignancies, but its application is particularly restricted due to limited understanding of the mechanism. Thus, a thorough understanding of epigenetic mechanism behind anti-leukemic effects of ATO would benefit the development of ATO-based anticancer strategy. Role of ATRA on APL associated epigenetic alterations has been extensively studied and reviewed. Recently, accumulating evidence suggest that ATO also induces some epigenetic changes that might favor APL eradication. In this article, we comprehensively discuss arsenic induced epigenetic changes and its relevance in APL treatment and beyond, so as to provide novel insights into overcoming arsenic resistance in APL and promote application of this drug to other malignancies.

Realgar (α-As4S4) Treats Myelodysplasic Syndromes through Reducing DNA Hypermethylation

DNA hypermethylation is an epigenetic modification that plays a critical role in the oncogenesis of myelodysplastic syndromes (MDS). Aberrant DNA methylation represses the transcription of promotors of tumor suppressor genes, inducing gene silencing. Realgar (α-As₄S₄) is a traditional medicine used for the treatment of various diseases in the ancient time. Realgar was reported to have efficacy for acute promyelocytic leukemia (APL). It has been demonstrated that realgar could efficiently reduce DNA hypermethylation of MDS. This review discusses the mechanisms of realgar on inhibiting DNA hypermethylation of MDS, as well as the species and metabolisms of arsenic in vivo.

Arsenic and the gastrointestinal tract microbiome

Arsenic is a toxin, ranking first on the Agency for Toxic Substances and Disease Registry and the Environmental Protection Agency Priority List of Hazardous Substances. Chronic exposure increases the risk of a broad range of human illnesses, most notably cancer; however, there is significant variability in arsenic-induced disease among exposed individuals. Human genetics is a known component, but it alone cannot account for the large inter-individual variability in the presentation of arsenicosis symptoms. Each part of the gastrointestinal tract (GIT) may be considered as a unique environment with characteristic pH, oxygen concentration, and microbiome. Given the well-established arsenic redox transformation activities of microorganisms, it is reasonable to imagine how the GIT microbiome composition variability among individuals could play a significant role in determining the fate, mobility and toxicity of arsenic, whether inhaled or ingested. This is a relatively new field of research that would benefit from early dialogue aimed at summarizing what is known and identifying reasonable research targets and concepts. Herein, we strive to initiate this dialogue by reviewing known aspects of microbe-arsenic interactions and placing it in the context of potential for influencing host exposure and health risks. We finish by considering future experimental approaches that might be of value.

Comparative health risk assessment of realgar and NiuHuangJieDu tablets based on tissue arsenic levels after multiple oral administration to rats

ETHNOPHARMACOLOGICAL RELEVANCE

Realgar (As₂S₂), a mineral traditional Chinese medicine (TCM), is proved to have great therapeutic effects in clinic and has been widely used in China for hundreds of years. As one of the most popular realgar-containing TCMs, NiuHuangJieDu Tablets (NHJDT) is used as OTC (over-the-counter) drug in daily life for fever relieving, detoxicating, as well as cure of sore throat and gingival swelling. However, the safety of realgar and its-containing TCMs still remains unclear.

AIM OF THE STUDY

This study was to investigate the accumulation of arsenic in rat body and evaluate the safety of realgar-containing TCMs in vivo.

MATERIALS AND METHODS

The health risk of arsenic was evaluated in rats by tissue distribution and histopathology, as well as arsenic speciation in plasma after multiple oral gavage of low and high doses of realgar and NiuHuangJieDu Tablets (NHJDT), respectively. Total arsenic and arsenic speciation were determined by hydride generation-atomic fluorescence spectrometry (HG-AFS) and high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS), respectively.

RESULTS

Arsenic accumulated in rat tissues especially in heart, liver, spleen, lung, kidney, uterus and ovary. Dimethylarsenic acid (DMA) was detected as the predominant species in rat plasma after dosing. In comparison of realgar, NHJDT with co-existing components significantly alleviated tissues injury, and reduced arsenic concentration in rat tissues and plasma.

CONCLUSIONS

NHJDT with co-existing components combination was relatively safer than realgar, but the accumulation of arsenic was still significant after long-term medication. Therefore, great attentions should be paid to realgar-containing TCMs to avoid toxicity from arsenic accumulation. Moreover, the dose regimen of realgar-containing TCMs should be designed rationally for clinical application. These results may provide useful references for the application of realgar-containing TCMs and might be helpful for the understanding of TCM compound compatibility.

Target lipidomics approach to reveal the resolution of inflammation induced by Chinese medicine combination in Liu-Shen-Wan against realgar overexposure to rats

ETHNOPHARMACOLOGICAL RELEVANCE

Liu-Shen-Wan (LSW) is one of the popular over-the-counter drugs in Asia, which contains realgar (As₄S₄), used for the treatment of upper respiratory tract inflammation and skin infections. However, the safety and potential risk of this arsenic remain unknown.

AIM OF THE STUDY

The aim of this study was to determine total arsenic in tissue and investigate effects of regular dose and overdose LSW exposure on rat liver.

MATERIALS AND METHODS

We used a target lipidomics approach to quantify inflammatory eicosanoids and employed ICP-MS to determine total arsenic in tissue.

RESULTS

The results showed that oral administration of 8 and 40 mg/kg LSW (1 and 5 fold human-equivalent dose) induced light changes of liver lipidomic profile in rats, which was associated with anti-inflammatory function of LSW. In our recent report, we observed that 41 and 134 mg/kg realgar (40 and 132 fold human-equivalent dose) stimulated rat liver inflammation through up-regulation of pro-inflammatory LOX-derived, CYP-derived HETEs and COX-derived PGs. However, we found that LSW in the form of drug combination, containing 41 and 134 mg/kg realger, could not stimulate these similar inflammatory responses in rats, although the liver total arsenic levels of the realger and LSW groups were same.

CONCLUSION

The downregulation of pro-inflammatory response showed that the LSW containing realger is safer than realger alone administrated to rats. These results suggested that Chinese medicines combination could reduce realgar-derived arsenic toxicity in rats.

Qing-Kai-Ling Injection Induces Immediate Hypersensitivity Reaction via the Activation of Anaphylatoxin C3

Background and Objective: Qing-Kai-Ling (QKL) is derived from a famous ancient Chinese patent medicine Angong Niuhuang pills (ANP) which has been used across Asia, especially in China, for the treatment of “febrile disease,” such as stroke, encephalitis and meningitis for hundreds of years. As an extract of ANP without heavy metal, the clinical applicability of QKL is more intensive, of which its injection is commonly used in acute and serious diseases. This study aims to clarify the potential mechanisms of immediate hypersensitivity reaction (IHR) induced by QKL injection (QKLI).

Methods: β-hexosaminidase release assay was performed on the human mast cell line LAD2 and mouse peritoneal mast cells. T helper 2 (Th2) immunity-amplified mice were prepared by aluminum adjuvant. Anaphylactic shock was detected by measuring rectal thermometry in propranolol-pretreated mice. For evaluating microvascular permeability, Evans Blue extravasation assay was used. Serum total IgE (tIgE) and the activated complement-derived anaphylatoxin C3 (C3a) levels were measured by ELISA.

Results: QKLI was unable to elevate serum tIgE level in the Th2 immunity-amplified mice, but can increase vasopermeability and trigger anaphylaxis after the first injection. By screening seven fractions of QKLI, only the extract of Isatidis Radix (Isatis tinctoria L.) induced hindpaw Evans Blue extravasation, which was disappeared in Isatidis Radix-free QKLI. Mechanism study indicated that QKLI or Isatidis Radix-caused IHR could be blocked by the antagonists for histamine or C3a, rather than PAF or C5a. Consistently, QKLI and Isatidis Radix could also directly activate human serum complement-derived anaphylatoxin 3 (C3) in vitro with the half effective concentration values of 0.69% and 218.6 μg/ml, respectively.

Conclusion: QKLI-IHR is complement activation-related pseudoallergy, rather than an IgE-mediated allergy. QKLI activates C3 and might consequently provoke mast cells to release histamine, which is a principal effector of its IHR. The pseudoallergic reaction induced by QKLI was attributed to the extract of Isatidis Radix. This study suggests a potential therapeutic strategy for the prophylaxis and treatment of QKLI-IHR.

Protective role of cinnabar and realgar in Hua-Feng-Dan against LPS plus rotenone-induced neurotoxicity and disturbance of gut microbiota in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Hua-Feng-Dan (HFD) is a traditional Chinese medicine used for neurological disorders. HFD contains cinnabar (HgS) and realgar (As₄S₄). The ethnopharmacological basis of cinnabar and realgar in HFD is not known.

AIM OF THE STUDY

To address the role of cinnabar and realgar in HFD-produced neuroprotection against neurodegenerative diseases and disturbance of gut microbiota.

MATERIALS AND METHODS

Lipopolysaccharide (LPS) plus rotenone (ROT)-elicited rat dopaminergic (DA) neuronal damage loss was performed as a Parkinson's disease animal model. Rats were given a single injection of LPS. Four months later, rats were challenged with the threshold dose of ROT. The clinical dose of HFD was administered via feed, starting from ROT administration for 46 days. Behavioral dysfunction was detected by rotarod and Y-maze tests. DA neuron loss and microglial activation were assessed via immunohistochemical staining and western bolt analysis. The colon content was collected to extract bacterial DNA followed by real-time PCR analysis with 16S rRNA primers.

RESULTS

LPS plus ROT induced neurotoxicity, as evidenced by DA neuron loss in substantia nigra, impaired behavioral functions and increased microglial activation. HFD-original (containing 10% cinnabar and 10% realgar) rescued loss of DA neurons, improved behavioral dysfunction and attenuated microglial activation. Compared with HFD-original, HFD-reduced (3% cinnabar and 3% realgar) was also effective, but to be a less extent, while HFD-removed (without cinnabar and realgar) was ineffective. In analysis of gut microbiome, the increased Verrucomicrobiaceae and Lactobacteriaceae, and the decreased Enterobacteeriaceae by LPS plus ROT were ameliorated by HFD-original, and to be the less extent by HFD-reduced.

CONCLUSION

Cinnabar and realgar are active ingredients in HFD to exert beneficial effects in a neurodegenerative model and gut microbiota.

Arsenic Bioaccessibility of Realgar Influenced by the Other Traditional Chinese Medicines in Niuhuang Jiedu Tablet and the Roles of Gut Microbiota

Niuhuang Jiedu tablet (NJT), a realgar (As2S2) containing Traditional Chinese Medicine (TCM), is a well-known formula. The safety of NJT is of growing concern since arsenic (As) is considered as one of the most toxic elements. NJT was demonstrated to be safer than realgar by our previous experiments and some other studies. The toxicity of realgar has been shown to be related to the amount of soluble or bioaccessible arsenic. In this study, the influences of the other TCMs in NJT on the bioaccessibility of arsenic from realgar, and the roles of gut microbiota during this process were investigated in vitro. Results showed that Dahuang (Rhei Radix et Rhizoma), Huangqin (Scutellariae Radix), Jiegeng (Platycodonis Radix), and Gancao (Glycyrrhizae Radix et Rhizoma) could significantly reduce the bioaccessibility of arsenic from realgar in artificial gastrointestinal fluids. Gut microbiota played an important role in decreasing the bioaccessibility of realgar because it was demonstrated to be able to absorb the soluble arsenic from realgar in the incubation medium. Dahuang, Huangqin, and Jiegeng could modulate the gut microbiota to enhance its arsenic absorption activity.

Highly Anisotropic Mechanical and Optical Properties of 2D Layered As2S3 Membranes

Two-dimensional (2D) materials with strong in-plane anisotropy are of interest for enabling orientation-dependent, frequency-tunable, optomechanical devices. However, black phosphorus (bP), the 2D material with the largest anisotropy to date, is unstable as it degrades in air. In this work we show that As₂S₃ is an interesting alternative, with a similar anisotropy to bP, while at the same time having a much higher chemical stability. We probe the mechanical and optical anisotropy in As₂S₃ by three distinct angular-resolved experimental methods: Raman spectroscopy, atomic force microscopy (AFM), and resonance frequency analysis. Using a dedicated angle-resolved AFM force-deflection method, an in-plane anisotropy factor of [Formula: see text] is found in the Young's modulus of As₂S₃ with E_a-axis = 79.1 ± 10.1 GPa and E_c-axis = 47.2 ± 7.9 GPa. The high mechanical anisotropy is also shown to cause up to 65% difference in the resonance frequency, depending on crystal orientation and aspect ratio of membranes.

Realgar and cinnabar are essential components contributing to neuroprotection of Angong Niuhuang Wan with no hepatorenal toxicity in transient ischemic brain injury

Realgar and cinnabar are commonly used mineral medicine containing arsenic and mercury in Traditional Chinese Medicine (TCM). Angong Niuhuang Wan (AGNHW) is a representative realgar- and cinnabar-containing TCM formula for treating acute ischemic stroke, but its toxicology and neuropharmacological effects are not well addressed. In this study, we compared the neuropharmacological effects of AGNHW and modified AGNHW in an experimental ischemic stroke rat model. Male SD rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) plus 22 h of reperfusion. Although oral administration of AGNHW for 7 days in the rats increased arsenic level in the blood and liver tissue, there were no significant changes in the arsenic level in kidney, mercury level in the blood, liver and kidney as well as hepatic and renal functions in MCAO rats. AGNHW revealed neuroprotective properties by reducing infarction volume, preserving blood-brain barrier integrity and improving neurological functions against cerebral ischemia-reperfusion injury. Interestingly, removing realgar and/or cinnabar from AGNHW abolished the neuroprotective effects. Meanwhile, AGNHW could scavenge peroxynitrite, down-regulate the expression of p47_phox, 3-NT and MMP-9 and up-regulate the expression of ZO-1 and claudin-5 in the ischemic brains, which were abolished by removing realgar and/or cinnabar from AGNHW. Notably, realgar or cinnabar had no neuroprotection when used alone. Taken together, oral administration of AGNHW for one week should be safe for treating ischemic stroke with neuroprotective effects. Realgar and cinnabar are necessary elements with synergetic actions with other herbal materials for the neuroprotective effects of AGNHW against cerebral ischemia-reperfusion injury.

Fatal acute arsenic poisoning by external use of realgar: Case report and 30 years literature retrospective study in China

Realgar (arsenic sulfide) is widely used in combination with other herbs as Chinese patent medicine to treat a variety of diseases in China. As a mineral arsenic, its mild toxicity was also well known. Longtime over-dose usage or wrongly oral intake of realgar can cause chronic arsenic poisoning and/or death, but acute fatal arsenic poisoning resulted from short-term dermal use of realgar-containing medicine was very rare. Here, we present the case of a 35-year-old Chinese man, who was diagnosed with severe psoriasis and died of fatal acute arsenic poisoning after he applied a local folk prescription ointment containing mainly the realgar to the affected skin for about 4 days. The autopsy showed multiple punctate hemorrhages over the limbs, pleural effusion, edematous lungs with consolidation, mild myocardial hypertrophy and normal-looking kidneys. The histopathological examination of renal tissue showed severe degeneration, necrosis and desquamation of renal tubular epithelial cells, presence of protein cast and a widened edematous interstitium with interstitial fibrosis. The presence of arsenic in large amount in the ointment (about 6%), in blood (1.76 μg/mL), and in skin (4.71 μg/g), were confirmed analytically. We also provide the clinical records of the deceased and briefly reviewed 7 similar cases in literature (6 in Chinese and 1 in English) in the past 30 years in China.

Chemical Compositions of Metals in Bhasmas and Tibetan Zuotai Are a Major Determinant of Their Therapeutic Effects and Toxicity

Minerals are alchemically processed as Bhasmas in Ayurvedic medicines or as Zuotai in Tibetan medicines. Ayurveda is a knowledge system of longevity and considers the mineral elixir made from “nature” capable of giving humans perpetual life. Herbo-metallic preparations have a long history in the treatment of various diseases in India, China, and around the world. Their disposition, pharmacology, efficacy, and safety require scientific evaluation. This review discusses the Bhasmas in Ayurvedic medicines and Zuotai in Tibetan medicines for their occurrence, bioaccessibility, therapeutic use, pharmacology, toxicity, and research perspectives. A literature search on Mineral, Bhasma, Ayurvedic medicine, Zuotai, Tibetan medicine, and Metals/metalloids from PubMed, Google and other sources was carried out, and the relevant papers on their traditional use, pharmacology, and toxicity were selected and analyzed. Minerals are processed to form Bhasma or Zuotai to alter their physiochemical properties distinguishing them from environmental metals. The metals found in Ayurveda are mainly from the intentional addition in the form of Bhasma or Zuotai. Bhasma and Zuotai are often used in combination with other herbals and/or animal-based products as mixtures. The advanced technologies are now utilized to characterize herbo-metallic preparations as Quality Assurance/Quality Control. The bioaccessibility, absorption, distribution, metabolism, and elimination of herbo-metallic preparations are different from environmental metals. The pharmacological basis of Bhasma in Ayurveda and Zuotai in Tibetan medicines and their interactions with drugs require scientific research. Although the toxic potentials of Bhasma and Zuotai differ from environmental metals, the metal poisoning case reports, especially lead (Pb), mercury (Hg), and arsenic (As) from inappropriate use of traditional medicines, are increasing, and pharmacovigilance is desired. In risk assessment, chemical forms of metals in Bhasma and Zuotai should be considered for their disposition, efficacy, and toxicity.

Lipidomic profiling of subchronic As4S4exposure identifies inflammatory mediators as sensitive biomarkers in rats

Arsenic sulfide compounds provide nearly all of the world's supply of arsenic.

Application of metabolomics in toxicity evaluation of traditional Chinese medicines

Traditional Chinese medicines (TCM) have a long history of use because of its potential complementary therapy and fewer adverse effects. However, the toxicity and safety issues of TCM have drawn considerable attention in the past two decades. Metabolomics is an “omics” approach that aims to comprehensively analyze all metabolites in biological samples. In agreement with the holistic concept of TCM, metabolomics has shown great potential in efficacy and toxicity evaluation of TCM. Recently, a large amount of metabolomic researches have been devoted to exploring the mechanism of toxicity induced by TCM, such as hepatotoxicity, nephrotoxicity, and cardiotoxicity. In this paper, the application of metabolomics in toxicity evaluation of bioactive compounds, TCM extracts and TCM prescriptions are reviewed, and the potential problems and further perspectives for application of metabolomics in toxicological studies are also discussed.