Organic Arsenic Research Articles

Modulation of aryl hydrocarbon receptor regulated genes by acute administration of trimethylarsine oxide in the lung, kidney and heart of C57BL/6 mice

1. Arsenite alters the expression of aryl hydrocarbon receptor (AhR)-regulated genes in extrahepatic tissues; yet, the effect of organic arsenicals still unknown. Therefore, C57BL/6 mice received trimethylarsine oxide (TMAO; 13 mg/kg i.p.) with or without 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 15 μg/kg), and euthanized at 6 or 24 h.2. Our results demonstrated that TMAO increased Cyp1a1 and Cyp1b1 mRNA, protein and activity in the lung. TMAO potentiated the TCDD-mediated induction of Cyp1a1 and Cyp1a2 mRNA, protein and activity in the lung. In the kidney, TMAO increased Cyp1b1 mRNA and protein. TMAO potentiated the TCDD-mediated induction of Cyp1a1 and Cyp1b1 mRNA, protein and activity. In the heart, TMAO potentiated the TCDD-mediated induction of Cyp1a1 and Cyp1b1 mRNA.3. Moreover, TMAO induced Nqo1 mRNA in the lung, kidney and heart, with subsequent increase in Nqo1 protein and activity in the lung. TMAO increased Gsta mRNA in the heart; and increased Gsta protein and activity in the lung and kidney. TMAO increased Nqo1 mRNA as compared to TCDD in the kidney and heart, and potentiated the TCDD-mediated induction of Gsta protein and activity in the kidney.4. In conclusion, TMAO modulates AhR-regulated genes in a tissue- and enzyme-specific manner.

Synthesis of two new arsenolipids and their identification in fish

Arsenolipids (AsL) of the type arsenic‐containing fatty acids (AsFA) and hydrocarbons (AsHC) are natural organoarsenic compounds present in high abundance in seafood. Since little is known about their toxicity, there is a significant concern about their health risk. Here we report the synthesis of two new AsL and their identification in fish by liquid chromatography (LC) coupled simultaneously to inductively coupled plasma mass spectrometry (ICP‐MS) and to high resolution mass spectrometry (HR‐MS). The molecular structure was elucidated on the basis of their exact mass and their product ion mass spectra. One of the synthesized AsL has been already identified in fish samples, meanwhile, the other arsenolipid is reported here as a natural product in fish.Practical applications: The synthesized AsL can be used as analytical standards to confirm the identification of AsL in different biological samples and to optimize analytical methods for their determination by liquid chromatography coupled simultaneously to ICP‐MS and HR‐MS. The material can be further used for toxicity testing of AsL and to study their uptake, bioavailability, and biotransformation.We report the synthesis of two new arsenolipids and their identification in fish by liquid chromatography (LC) coupled simultaneously to inductively coupled plasma mass spectrometry (ICP‐MS) and to high resolution mass spectrometry (HR‐MS). One of the synthesized arsenolipid has been already identified in fish samples, meanwhile, the other arsenolipid is reported for the first time here as a natural product in fish.

Endocrine disruptors: Can it be the missing link explaining the diabetes epidemic in India?

AbstractIndia is the diabetes capital of the world with an exponential increase in diabetes prevalence in the last few decades. It may not be just a simple co-incidence that the global increase in diabetes is associated with an exponential increase in industrial chemical output. Literature searches through PubMed, Medline and Embase for articles published until July 2014 evaluating link between endocrine disrupting chemicals (EDCs) and diabetes was done. This review observed that a large volume of data is available from preclinical studies implicating commonly used synthetic compounds in the pathogenesis of diabetes. EDCs have been demonstrated to interact with almost all the steps of insulin homeostasis starting from its synthesis to its signaling and action. Bisphenol-A, 2,3,7,8-tetrachlorod-ibenzo-dioxin (TCDD)/dioxin, polychlorinated biphenyls (PCBs), persistent organic pollutants, diethylhexylphthalate, cadmium and arsenic are some of the important EDCs which interfere with a maximal number of pathways of insulin homeostasis. However data from humans establishing the causality lacks from across the globe, with maximal data available from bisphenol-A and TCDD from USA. Their evaluation among Indians, especially with regards to dysglycemia, insulin resistance and beta cell function is non-existent, thus warranting urgent research in this area.

What Are the Current Findings Concerning Arsenic in Foods?

What Are the Current Findings Concerning Arsenic in Foods?

Arsenic Speciation in Honeysuckle (Lonicera japonica Thunb.) from China.

In this study, honeysuckle, a common Chinese herbal medicine, produced from different areas was investigated for total arsenic and arsenic species concentration. The total arsenic concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS) and ranged from 275 to 635μgkg(-1). A microwave-assisted procedure with 1% phosphoric acid (v/v) was used for the extraction of arsenic species in honeysuckle. The total arsenic species concentration found by liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS) was in agreement with the total arsenic concentration determined by the ICP-MS analysis after the microwave digestion. Arsenate (As(V)) with an average proportion of 54.3% was the predominant arsenic species in honeysuckle. The order of concentration is as follows: As(V) > arsenite (As(III)) > dimethylarsinic acid (DMA) > arsenobetaine (AsB) > monomethylarsonic acid (MMA). The proportion of organic arsenic (24.7%) was higher than that in most terrestrial plants. Moreover, the distributions of arsenic species in the honeysuckle from different producing areas were significantly different. This study provides useful information for better understanding of the distribution of arsenic species in terrestrial plants.

Arsenic speciation and Fucoxanthin analysis from seaweed dietary supplements using LC-ICP-MS

The study involves the analysis of total arsenic in metallic form, organic and inorganic arsenic species from seaweeds and dietary supplements. The analysis provides data for dietary exposure estimates of inorganic species which are considered more toxic to humans than organic arsenic and total arsenic. Total arsenic was determined by acid digestion followed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The optimum arsenic speciation method was determined to be water extraction followed by anion exchange HPLC coupled with ICP-MS. Optimization of chromatographic conditions led to baseline separation for six arsenic species, including arsenic acid, arsenous acid, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, and arsenocholine, in approximately 8 min using gradient elution. Detection limits for all 6 compounds were in the range from 10 – 15 ng/mL. The data presented here will be valuable for the quality assurance of analytical method development and surveys of total arsenic and arsenic species in dietary supplements. The most abundant arsenic species found were arsenite (As III) and arsenate (As V). In addition, the dietary supplements purported to contain fucoxanthin, a carotenoid having pharmacological activities were analyzed using UHPLC-UV-MS.

Phytotoxicity of arsenic compounds on crop plant seedlings.

The effects of inorganic and organic arsenic on the germination and seedling growth of 10 crop plants were investigated to elucidate the relationship between toxicity and the arsenic chemical states. Two types of soils, soil A and B, were also tested to determine how physicochemical properties of soils were related to toxicity of arsenic and the sensitivity of the plants. All tested plant species, except mung bean and cucumber, showed inhibition of germination by two types of inorganic arsenic, arsenite, and arsenate, while the organic arsenic compound, dimethylarsinic acid (DMA), had no inhibitory effects on plants in soil A. In contrast, the growth of seedlings of all 10 plant species was sensitive to the presence of arsenic. The sensitivity of the plants toward inorganic arsenic compounds showed similar trends but differed for DMA. Overall, seedling growth was a more sensitive endpoint to arsenic toxicity than germination, and the relative toxicity of arsenic compounds on plants was arsenite > DMA > arsenate. Interestingly, the sensitivity of wheat varied significantly when the soil was changed, and the DMA was most toxic rather than arsenite in soil B. Thus, the systematic study employed here provides insights into the mechanisms of arsenic toxicity in different plant species and the role of physicochemical properties of soils.

Organic arsenicals as efficient and highly specific linkers for protein/peptide-polymer conjugation.

The entropy-driven affinity of trivalent (in)organic arsenicals for closely spaced dithiols has been exploited to develop a novel route to peptide/protein-polymer conjugation. A trivalent arsenous acid (As(III)) derivative (1) obtained from p-arsanilic acid (As(V)) was shown to readily undergo conjugation to the therapeutic peptide salmon calcitonin (sCT) via bridging of the Cys(1)-Cys(7) disulfide, which was verified by RP-HPLC and MALDI-ToF-MS. Conjugation was shown to proceed rapidly (t < 2 min) in situ and stoichiometrically through sequential reduction-conjugation protocols, therefore exhibiting conjugation efficiencies equivalent to those reported for the current leading disulfide-bond targeting strategies. Furthermore, using bovine serum albumin as a model protein, the trivalent organic arsenical 1 was found to demonstrate enhanced specificity for disulfide-bond bridging in the presence of free cysteine residues relative to established maleimide functional reagents. This specificity represents a shift toward potential orthogonality, by clearly distinguishing between the reactivity of mono- and disulfide-derived (vicinal or neighbors-through-space) dithiols. Finally, p-arsanilic acid was transformed into an initiator for aqueous single electron-transfer living radical polymerization, allowing the synthesis of hydrophilic arsenic-functional polymers which were shown to exhibit negligible cytotoxicity relative to a small molecule organic arsenical, and an unfunctionalized polymer control. Poly(poly[ethylene glycol] methyl ether acrylate) (PPEGA480, DPn = 10, Mn,NMR = 4900 g·mol(-1), Đ = 1.07) possessing a pentavalent arsenic acid (As(V)) α-chain end was transformed into trivalent As(III) post-polymerization via initial reduction by biological reducing agent glutathione (GSH), followed by binding of GSH. Conjugation of the resulting As(III)-functional polymer to sCT was realized within 35 min as indicated by RP-HPLC and verified later by thermodynamically driven release of sCT, from the conjugate, in the presence of strong chelating reagent ethanedithiol.

Interactions between natural organic matter, sulfur, arsenic and iron oxides in re-oxidation compounds within riparian wetlands: NanoSIMS and X-ray adsorption spectroscopy evidences

Arsenic (As) is a toxic and ubiquitous element which can be responsible for severe health problems. Recently, Nano-scale Secondary Ions Mass Spectrometry (nanoSIMS) analysis has been used to map organomineral assemblages. Here, we present a method adapted from Belzile et al. (1989) to collect freshly precipitated compounds of the re-oxidation period in a natural wetland environment using a polytetrafluoroethylene (PTFE) sheet scavenger. This method provides information on the bulk samples and on the specific interactions between metals (i.e. As) and the natural organic matter (NOM). Our method allows producing nanoSIMS imaging on natural colloid precipitates, including 75As−, 56Fe16O−, sulfur (32S−) and organic matter (12C14N) and to measure X-ray adsorption of sulfur (S) K-edge. A first statistical treatment on the nanoSIMS images highlights two main colocalizations: (1) 12C14N−, 32S−, 56Fe16O− and 75As−, and (2) 12C14N−, 32S− and 75As−. Principal component analyses (PCAs) support the importance of sulfur in the two main colocalizations firstly evidenced. The first component explains 70% of the variance in the distribution of the elements and is highly correlated with the presence of 32S−. The second component explains 20% of the variance and is highly correlated with the presence of 12C14N−. The X-ray adsorption near edge spectroscopy (XANES) on sulfur speciation provides a quantification of the organic (55%) and inorganic (45%) sulfur compositions. The co-existence of reduced and oxidized S forms might be attributed to a slow NOM kinetic oxidation process. Thus, a direct interaction between As and NOM through sulfur groups might be possible.

Adsorptive removal of p-arsanilic acid from water using mesoporous zeolitic imidazolate framework-8

The adsorptive removal of p-arsanilic acid (ASA) from water using zeolitic imidazolate framework-8 (ZIF-8) materials was investigated for the first time. The adsorption kinetics and adsorbed amount of ASA were improved by introducing mesoporosity into the pristine ZIF-8 structure. The high adsorption capacity of mesoporous ZIF-8 for ASA and facile regeneration of the used adsorbent show that mesoporous ZIF-8 has potential applications in the adsorptive removal of organoarsenic compounds such as ASA. Based on the adsorption results at various pH values and the surface charges on ZIF-8s, the adsorption mechanism of ASA on ZIF-8s can be explained by electrostatic interactions between the positively charged ZIF-8 surface and the anionic forms of ASA.

A Study on Arsenic Speciation in Korean Oyster Samples using Ion Chromatography Inductively Coupled Plasma Mass Spectrometry

The qualitative and quantitative analysis of the different arsenic species in Korean oyster samples was performed to provide the vital information of food safety of the marine sample in terms of the arsenic species. Korean marine samples, oysters, were obtained from nine sites in the western and southern areas of South Korea. Inductively coupled plasma mass spectrometry (ICP‐MS) was used to measure the total arsenic. The different arsenic species in the oyster were separated by ion chromatography (IC), and then detected by ICP‐MS. Extraction of arsenic species was performed with the mixed solvent of the methanol:water (3:1). The extraction efficiency of arsenic species (the ratio of total amount of the different arsenic species to the total arsenic in the oyster) for nine oysters was approximately 73–81%. The major arsenic species in the oyster was arsenobetaine, and its concentration in the samples was in the range of 7–16 mg/kg that was more than 90% of the total organic arsenic in the oyster. As(III) was not generally detected while the trace As(V) was detected in most oysters.

Ten-years records of organic arsenic (diphenylarsinic acid) poisoning: epidemiology, clinical feature, metabolism, and toxicity

We report here the symptoms of diphenylarsinic acid (DPAA) poisoning recorded over 10 years since the DPAA contamination of the potable well water was first detected in the Kamisu City, Ibaraki Prefecture, in 2003. The poisoning symptoms associated with the cerebellum and brainstem included nystagmus, tremors, myoclonus, and cerebellar ataxia as well as the symptoms associated with the temporal and occipital lobes such as memory impairment, sleep disorder, and visual disturbance. Some of the affected children exhibited mental retardation. Moreover, reduced blood flow and reduced glucose metabolism in the cerebella, brainstem, and temporal and occipital lobes persisted for several years among the DPAA-exposed persons. Based on the animal studies for DPAA intoxication, the target organs for the DPAA toxicity were determined to be the central nervous system (CNS), liver, and biliary system. In particular, DPAA tends to persist in the brain for a long time, resulting in long-term impacts on the brain. The cerebral blood flow and brain glucose metabolism, which can be measured by positron emission tomography (PET) and single photon emission computed tomography (SPECT), respectively, are useful objective clinical markers to determine the effect of DPAA on CNS. We believe that continuous monitoring of the DPAA-exposed people may promote the effect of carcinogen and accelerate brain aging.

Biosensors for inorganic and organic arsenicals.

Arsenic is a natural environmental contaminant to which humans are routinely exposed and is strongly associated with human health problems, including cancer, cardiovascular and neurological diseases. To date, a number of biosensors for the detection of arsenic involving the coupling of biological engineering and electrochemical techniques has been developed. The properties of whole-cell bacterial or cell-free biosensors are summarized in the present review with emphasis on their sensitivity and selectivity. Their limitations and future challenges are highlighted.

Effect of central metal ions of analogous metal-organic frameworks on adsorption of organoarsenic compounds from water: plausible mechanism of adsorption and water purification.

The adsorptive removal of organoarsenic compounds such as p-arsanilic acid (ASA) and roxarsone (ROX) from water using metal-organic frameworks (MOFs) has been investigated for the first time. A MOF, iron benzenetricarboxylate (also called MIL-100-Fe) exhibits a much higher adsorption capacity for ASA and ROX than activated carbon, zeolite (HY), goethite, and other MOFs. The adsorption of ASA and ROX over MIL-100-Fe is also much more rapid than that over activated carbon. Moreover, the used MIL-100-Fe can be recycled by simply washing with acidic ethanol. Therefore, it is determined that a MOF such as MIL-100-Fe can be used to remove organoarsenic compounds from contaminated water because of its high adsorption capacity, rapid adsorption, and ready regeneration. Moreover, only one of three analogous MIL-100 species (MIL-100-Fe, rather than MIL-100-Al or MIL-100-Cr) can effectively remove the organoarsenic compounds. This selective and high adsorption over MIL-100-Fe, different from other analogous MIL-100 species, can be explained (through calculations) by the facile desorption of water from MIL-100-Fe as well as the large (absolute value) replacement energy (difference between the adsorption energies of the organoarsenic compounds and water) exhibited by MIL-100-Fe. A plausible adsorption/desorption mechanism is proposed based on the surface charge of the MOFs, FTIR results, calculations, and the reactivation results with respect to the solvents used in the experiments.

Attenuation of arsenic in a karst subterranean stream and correlation with geochemical factors: A case study at Lihu, South China

Arsenic (As) pollutants generated by human activities in karst areas flow into subterranean streams and contaminate groundwater easily because of the unique hydrogeological characteristics of karst areas. To elucidate the reaction mechanisms of arsenic in karst subterranean streams, physical–chemical analysis was conducted by an inductively coupled plasma mass spectrometer and an X-ray fluorescence spectrometer. The results show that inorganic species account for most of the total arsenic, whereas organic arsenic is not detected or occurs in infinitesimal amounts. As(III) accounts for 51.0%±9.9% of the total inorganic arsenic. Arsenic attenuation occurs and the attenuation rates of total As, As(III) and As(V) in the Lihu subterranean stream are 51%, 36% and 59%, respectively. To fully explain the main geochemical factors influencing arsenic attenuation, SPSS 13.0 and CANOCO 4.5 bundled with CanoDraw for Windows were used for simple statistical analysis and redundancy analysis (RDA). Eight main factors, i.e., sediment iron (SFe), sediment aluminum (SAl), sediment calcium (SCa), sediment organic matter (SOM), sediment manganese (SMn), water calcium (WCa2+), water magnesium (WMg2+), and water bicarbonate ion (WHCO3−) were extracted from thirteen indicators. Their impacts on arsenic content rank as: SFe>SCa>WCa2+>SAl>WHCO3−>SMn>SOM>WMg2+. Of these factors, SFe, SAl, SCa, SOM, SMn, WMg2+ and WCa2+ promote arsenic attenuation, whereas WHCO3− inhibits it. Further investigation revealed that the redox potential (Eh) and pH are adverse to arsenic removal. The dramatic distinction between karst and non-karst terrain is that calcium and bicarbonate are the primary factors influencing arsenic migration in karst areas due to the high calcium concentration and alkalinity of karst water.

Kinetics and activation parameters of the reaction of organoarsenic(V) compounds with glutathione

In this work the kinetics of the reaction of glutathione (GSH) with the organoarsenic(V) compounds phenylarsonic acid (PAA), 4-hydroxy-3-nitrophenylarsonic acid (HNPAA), p-aminophenylarsonic acid (p-APAA) and o-aminophenylarsonic acid (o-APAA) as well as monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA) is investigated. The reaction progress is monitored in real time by 1H NMR, allowing the determination of rate coefficients and half-lives as well as activation parameters. The reaction consists of two steps: redox reaction and conjugation. In all investigated systems the conjugation is fast compared to the redox reaction and, therefore, rate determining. All investigated phenylarsonic acids follow the same rate law, showing overall reaction orders of 3 and half-lives between 47.7±0.2 and 71.0±3.6min. The methylated compounds react slower, showing half-lives of 76.6±0.4 and 444±10min for DMAA and MMAA, respectively. Enthalpies of activation range from 20 to 36 (±2)kJmol−1 and the entropies of activation are within −154 and −97(±7)Jmol−1K−1. The results reveal a correlation of the toxicity of the arsenic compound and the reaction rate with GSH. This may pave the way for the estimation of the toxicity of such compounds by simple kinetic studies.

Time course of arsenic-induced alterations in paraoxonase activity in male albino rats: Comparison between pentavalent inorganic and organic arsenic through drinking water

Time course of arsenic-induced alterations in paraoxonase activity in male albino rats: Comparison between pentavalent inorganic and organic arsenic through drinking water

Conversion and Species Distribution Characteristics of Arsenical Chemical Agent in the Soil Contaminated by Chemical Weapons Abandoned by Japan

In order to phytoremediation the soils contaminated by arsenical chemical weapons abandoned by Japan at some region of Jilin Province and ready for the estimate of the ecological safety, this paper analyzed organic species in soil with GC-MS, disscussed extraction and testing of inorganic arsenic in soil with hydrochloric acid, studied species of arsenic in soil such as available forms, valence state, and combined state, and inferred conversion process of arsenical chemical agent. The results indicate that after simple destroying and long time burial, almost all arsenical chemical agents in soil at this region are converted into inorganic arsenic due to explosion, burning, natural oxidation and microorganism, which primarily exists as As (V). Organic arsenic was only detected at where shells were buried (destroyed), in leaded shells and contaminated soil, with its content 3.65%~32.03%; Organic arsenic content of soil in other part is less than 10%. In contaminated soil of this region, water soluble arsenic and available arsenic extracted from disodium hydrogen phosphate take 0.81~2.58% and 7.49~15.96% of total arsenic respectively. Exchangeable As and binding As (Al-As, Fe-As, reducible As and Ca-As) take 40% of total arsenic, residual As takes 49.38~66.43%. The results may be used as basis for determining remedy methods and assessing ecological safety at this region.

Seasonal variations of arsenic at the sediment–water interface of Poyang Lake, China

Arsenic species including arsenite, arsenate, and organic arsenic were measured in the porewaters collected from Poyang Lake, the largest freshwater lake of China. The vertical distributions of dissolved arsenic species and some diagenetic constituents [Fe(II), Mn(II), S(−II)] were also obtained in the same porewater samples in summer and winter. In sediments the concentration profiles of total As and As species bound to Fe–Mn oxyhydroxides and to organic matter were also determined along with the concentrations of Fe, Mn and S in different extractable fractions. Results indicate that, in the summer season, the concentrations of total dissolved As varying from 3.9 to 55.8μg/L in sediments were higher than those (5.3–15.7μg/L) measured in the winter season, while the concentrations of total As species in the solid phase varied between 10.97 and 25.32mg/kg and between 7.84 and 30.52mg/kg on a dry weight basis in summer and winter, respectively. Seasonal profiles of dissolved As suggest downward and upward diffusion, and the flux of dissolved As across the sediment–water interface (SWI) in summer and winter were estimated at 3.88mg/m2a and 0.79mg/m2a, respectively. Based on porewater profiles and sediment phase data, the main geochemical behavior of As was controlled by adsorption/desorption, precipitation and molecular diffusion. The solubility and migration of inorganic As are controlled by Fe–Mn oxyhydroxides in summer whereas they appear to be more likely controlled by both amorphous Fe–Mn oxyhydroxides and sulfides in winter. A better knowledge of the cycle of As in Poyang Lake is essential to a better management of its hydrology and for the environmental protection of biota in the lake.

Preparation and application of sol–gel acrylate and methacrylate solid-phase microextraction fibres for gas chromatographic analysis of organoarsenic compounds

Novel solid-phase microextraction (SPME) fibres containing methyl, ethyl, butyl acrylate and methacrylate were first prepared by a sol–gel technique and investigated for determination of selected organoarsenic compounds (lewisite, methyldichloroarsine, phenyldichloroarsine, diphenylchloroarsine and triphenylarsine) from water samples. The influence of sorption and desorption temperature and time for extraction efficiency were examined. The best new fibre coatings (methyl acrylate (MA), methyl methacrylate (MMA) and combination of methyl acrylate and methacrylate (MA/MMA)) for analysis of organoarsenic compounds were selected and compared with commercial fibres. The distribution coefficients Kfs were determined for the best novel fibres and for absorption commercial fibres. The highest Kfs value were obtained for MA/MMA and MMA fibres and were respectively 9458 and 6561 for lewisite and 6458 and 5884 for triphenylarsine. The limit of detection and quantification were determined for the three laboratory obtained fibres (MA, MMA and MA/MMA). LODs for tested fibres, at a signal-to-noise of 3, were 0.03–0.3ngmL−1. LOQs for selected coatings, at signal-to-noise of 10, were 0.1–0.8ngmL−1. The relative standard deviations (RSD) for all measurements were 4.3–6.5% (n=9) and relative errors were 2.5–5%. The laboratory obtained fibres were used for environmental analysis of pore water samples from the Baltic Sea.