Chelation in metal intoxication

Thorium decorporation efficacy of rationally-selected biocompatible compounds with relevance to human application

During civil, nuclear or defense activities, internal contamination of actinides in humans and mitigation of their toxic impacts are of serious concern. Considering the health hazards of thorium (Th) internalization, an attempt was made to examine the potential of ten rationally-selected compounds/formulations to decorporate Th ions from physiological systems. The Th-induced hemolysis assay with human erythrocytes revealed good potential of tiron, silibin (SLB), phytic acid (PA) and Liv.52^® (L52) for Th decorporation, in comparison to diethylenetriaminepentaacetic acid, an FDA-approved decorporation drug. This was further validated by decorporation experiments with relevant human cell models (erythrocytes and liver cells) and biological fluid (blood) under pre-/post-treatment conditions, using inductively coupled plasma mass spectrometry (ICP-MS) and transmission electron microscopy (TEM). Furthermore, density functional theory-based calculations and extended X-ray absorption fine structure (EXAFS) spectroscopy confirmed the formation of Th complex by these agents. Amongst the chosen biocompatible agents, tiron, SLB, PA and L52 hold promise to enhance Th decorporation for human application.

Heavy metals detoxification: A review of herbal compounds for chelation therapy in heavy metals toxicity

Some heavy metals are nutritionally essential elements playing key roles in different physiological and biological processes, like: iron, cobalt, zinc, copper, chromium, molybdenum, selenium and manganese, while some others are considered as the potentially toxic elements in high amounts or certain chemical forms. Nowadays, various usage of heavy metals in industry, agriculture, medicine and technology has led to a widespread distribution in nature raising concerns about their effects on human health and environment. Metallic ions may interact with cellular components such as DNA and nuclear proteins leading to apoptosis and carcinogenesis arising from DNA damage and structural changes. As a result, exposure to heavy metals through ingestion, inhalation and dermal contact causes several health problems such as, cardiovascular diseases, neurological and neurobehavioral abnormalities, diabetes, blood abnormalities and various types of cancer. Due to extensive damage caused by heavy metal poisoning on various organs of the body, the investigation and identification of therapeutic methods for poisoning with heavy metals is very important. The most common method for the removal of heavy metals from the body is administration of chemical chelators. Recently, medicinal herbs have attracted the attention of researchers as the potential treatments for the heavy metals poisoning because of their fewer side effects. In the present study, we review the potential of medicinal herbs such as: Allium sativum (garlic), Silybum marianum (milk thistle), Coriandrum sativum (cilantro), Ginkgo biloba (gingko), Curcuma longa (turmeric), phytochelatins, triphala, herbal fibers and Chlorophyta (green algae) to treat heavy metal poisoning.

The diagnosis and management of idiosyncratic drug-induced liver injury

Drug-induced liver injury (DILI) is an uncommon but important cause of liver disease that can arise after exposure to a multitude of drugs and herbal and dietary supplements. The severity of idiosyncratic DILI varies from mild serum aminotransferase elevations to the development of severe liver injury that can progress to acute liver failure resulting in death or liver transplantation within days of DILI onset. Chronic liver injury that persists for more than 6 months after DILI onset is also becoming increasingly recognized in up to 20% of DILI patients. Host demographic (age, gender, race), clinical and laboratory features at DILI onset have been associated with the severity and outcome of liver injury in DILI patients. In addition to cessation of the suspect drug, other medical interventions including the use of N-acetylcysteine and corticosteroids in selected patients have shown some clinical benefit, but additional prospective studies are needed. A number of promising diagnostic, prognostic and mechanistic serum and genetic biomarkers may help improve our understanding of the pathogenesis and treatment of idiosyncratic DILI.

Prophylactic Administration of Nanocurcumin Abates the Incidence of Liver Toxicity Induced by an Overdose of Copper Sulfate: Role of CYP4502E1, NF-κB and Bax Expressions

Background

The consequences of excess copper in human tissue are the alterations in the oxidative stress markers and peroxidative damage of membrane lipids. Unselective copper binding may be the clue to damaging impact to protein construction and hence modifying their biological functions. The aim of this study is to match the hepatoprotective efficacy of curcumin (CM) or nanocurcumin (NCM) with that of desferrioxamine (DSF; standard heavy metal chelator) against toxic doses of copper sulphate (CuSO₄).

Method

All treatments were given simultaneously with CuSO₄ for 7 days.

Result

CuSO₄ administration elevated serum alanine transaminase, and hepatic nitric oxide (NO), lipid peroxide, and caspase-3 as well as protein expression of cytochrome P4502E1, and nuclear factor-κB (NF-κB) and Bax gene expressions. On the other hand, hepatic levels of reduced glutathione, superoxide dismutase, and interleukin-10 were decreased, whereas DNA degradation was increased as well compared with the control group. The administration of the aforementioned antioxidants ameliorated all the previous altered measured parameters. Interestingly, NCM achieved the most pronounced hepatoprotective effect nearly equivalent to that of DSF.

Conclusion

It was concluded that NCM is considered a promising candidate against CuSO₄ toxicity, and cytochrome P450, NF-κB, and Bax are involved in its toxicity and treatment.

Reversing the adverse biochemical effects in lead-intoxicated rats by N,N`- bis[(1,2-didehydro-1-hydroxy-2-thioxopyrid-4-yl)-carbonyl]- L-lysine

N,N`-Bis[(1,2-didehydro-1-hydroxy-2-thioxopyrid-4-yl)-carbonyl]- L-lysine (HTPL) is a novel newly synthesized compound intended to be used for the chelation of lead in intoxicated animals. Subchronic lead intoxication experiments were carried out on Wistar male rats; these rats were intoxicated with lead and then treated with HTPL. Results were compared with those obtained with known compounds used for lead chelation therapy, such as disodium ethylnediaminetetraacetic acid (CaNa₂EDTA) and meso-2,3-dimercaptosuccininc acid (DMSA), using different routes of administration. Biological samples of whole blood and urine were collected and analyzed for urinary proporphyrins, δ-aminolevulinic acid dehydratase, and zinc protoporphyrin. Results revealed that HTPL can remarkably reverse the toxic effects of lead intoxication at biochemical levels. Additionally, results showed that this agent is as good or even more potent than calcium disodium ethylnediaminetetraacetic acid (CaNa₂EDTA) and meso-2,3-dimercaptosuccininc acid (DMSA) in reversing the toxic effect of lead. More importantly, HTPL was found effective when administrated intraperitoneally and orally.

Nickel spiking to improve the methane yield of sewage sludge

The presence of micro-nutrients can be stimulatory for the anaerobic digestion (AD) of hardly degradable wastes and thus, improve process performance. Among the essential trace elements, nickel is involved in multiple important enzymes necessary for efficient AD. The present study investigates the effect of nickel spiked sewage sludge on batch and continuous mode operation. Metal spiking was conducted in the form of nanoparticles (Ni-NPs) and salt (NiCl₂·6H₂O). Results from batch assays showed that 5 mgNi-Salt/kgVS in the presence of Nitrilotriacetic acid (NTA) enhanced the methane yield by ∼10% compared to the untreated sample. The impact of Ni-NPs in the AD process was also positive, but slightly lower compared to the effect of NiCl₂·6H₂O. The stimulatory impact of Ni was also revealed in continuously fed digester boosting the methane yield by ∼8%. Overall, the improved methane production indicated that methanogenic archaea were favoured by the simultaneous supplementation of Ni and NTA.

N-Acetylcysteine reverses silver nanoparticle intoxication in rats

The increasing use of silver nanoparticles (AgNPs) in consumer products raises the risk of human toxicity. Currently, there are no therapeutic options or established treatment protocols in cases of AgNPs intoxication. We demonstrated previously that thiol antioxidants compounds can reverse the cytotoxicity induced by AgNPs in Huh-7 hepatocarcinoma cells. Here, we investigated the use of N-acetylcysteine (NAC) against the systemic toxic effects of AgNPs (79.3 nm) in rats. Biochemical, histopathological, hematological, and oxidative parameters showed that a single intravenous injection of AgNPs (5 mg/kg b.w.) induced deleterious effects such as hepatotoxicity, potentially as a result of AgNPs accumulation in the liver. Treatment with a single intraperitoneal injection of NAC (1 g/kg b.w.) one hour after AgNPs exposure significantly attenuated all toxic effects evaluated and altered the bioaccumulation and release patterns of AgNPs in rats. The findings show that NAC may be a promising candidate for clinical management of AgNPs intoxication.

Ameliorative effect of gallic acid on sodium arsenite-induced spleno-, cardio- and hemato-toxicity in rats

AIM

Arsenic is an important toxic chemical affecting millions of people around the world. Exposure to inorganic arsenic results in various health problems including skin lesions, hypertension, hematological disturbance, cardiovascular disease, spleen enlargement and cancer. Gallic acid (GA) is an important phenolic compound possessing various pharmacological properties including anti-inflammatory, antioxidant and free radical scavenging activities. The present study investigated effects of GA against sodium arsenite (SA)-induced spleno-, cardio- and hemato-toxicity.

MAIN METHODS

Thirty-five adult male Wistar rats were randomly divided into five groups; group I received normal saline (2 ml/kg/day, p.o.) for 21 days, group II received SA (10 mg/kg/day, p.o.) for 14 days, group III and IV were treated with GA (10 and 30 mg/kg/day, respectively) for 7 days prior to receive SA and treatment was continued up to 21 days in parallel with SA administration, group V received GA (30 mg/kg/day, p.o.) for 21 days. The level of MDA, NO and glutathione (GSH) and the activity of glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase were measured in heart and spleen tissues. Creatine kinase-MB (CK-MB) activity and hematological and histopathological parameters were also assessed.

KEY FINDINGS

GA significantly decreased SA-induced elevation of MDA and NO levels and reduction of GSH level and GPx and SOD activity in heart and spleen tissues. Furthermore, GA improved SA-induced alteration in hematological and histopathological parameters and reduced SA-induced elevation of serum CK-MB activity.

SIGNIFICANCE

Our results suggest that GA inhibits SA-induced spleno-, cardio- and hemato-toxicity through reducing oxidative stress.

Simulating the Chelate Effect

Despite the rich history of experimental studies focusing on the thermochemistry and kinetics associated with the chelate effect, molecular-level computational studies on the chelate ring opening/ring closure are scarce. The challenge lies in an accurate description of both the metal ion and its aqueous environment. Herein, we demonstrate that an optimized 12-6-4 Lennard-Jones (LJ) model can capture the thermodynamics and provide detailed structural and mechanistic insights into the formation of ethylenediamine (en) complexes with metal ions. The water molecules in the first solvation shell of the metal ion are found to facilitate the chelate ring formation. The optimized parameters further simulate the formation of bis and tris(en) complexes representing the wide applicability of the model to simulate coordination chemistry and self-assembly processes.

An overview of plant-based interventions to ameliorate arsenic toxicity

The industrial and technological advancements in the world have also contributed to the rapid deterioration in the environment quality through introduction of obnoxious pollutants that threaten to destroy the subtle balance in the ecosystem. The environment contaminants cause severe adverse effects to humans, flora and fauna that are mostly irreversible. Chief among these toxicants is arsenic, a metalloid, which is considered among the most dangerous environmental toxins that leads to various diseases which affect the quality of life even when present in small quantities. Treatment of arsenic-mediated disorders still remains a challenge due to lack of effective options. Chelation therapy has been the most widely used method to detoxify arsenic. But this method is associated with deleterious effects leading various toxicities such as hepatotoxicity, neurotoxicity and other adverse effects. It has been discovered that indigenous drugs of plant origin display effective and progressive relief from arsenic-mediated toxicity without any side-effects. Further, these phytochemicals have also been found to aid the elimination of arsenic from the biological system and therefore can be more effective than conventional therapeutic agents in ameliorating arsenic-mediated toxicity. This review presents an overview of the toxic effects of arsenic and the therapeutic strategies that are available to mitigate the toxic effects with emphasis on chelation as well as protective and detoxifying activities of different phytochemicals and herbal drugs against arsenic. This information may serve as a primer in identifying novel prophylactic as well as therapeutic formulations against arsenic-induced toxicity.

Radiostrontium transport in plants and phytoremediation

Radiostrontium is a common product of nuclear fission and was emitted into the environment in the course of nuclear weapon tests as well as from nuclear reactor accidents. The release of ⁹⁰Sr and ⁸⁹Sr into the environment can pose health threats due to their characteristics such as high specific activities and easy access in human body due to its chemical analogy to calcium. Radiostrontium enters the human food chain by the consumption of plants grown on sites comprising fission-derived radionuclides. For humans, Sr is not an essential element, but, due to solubility in water and homology with calcium, once interred in the body, it gets deposited in bones and in teeth. This concern has drawn the attention of researchers throughout the globe to develop sustainable treatment processes to remediate soil and water resources. Nowadays, phytoremediation has become a promising approach for the remediation of large extents of toxic heavy metals. Some of the plants have been reported to accumulate Sr inside their biomass but detailed mechanisms at genetic level are still to be uncovered. However, there is inadequate information offered to assess the possibility of this remediation approach. This review highlights phytoremediation approach for Sr and explains in detail the uptake mechanism inside plants.

Phytofabrication of Iron Nanoparticles for Hexavalent Chromium Remediation

Hexavalent chromium is a genotoxic and carcinogenic byproduct of a number of industrial processes, which is discharged into the environment in excessive and toxic concentrations worldwide. In this paper, the synthesis of green iron oxide nanoparticles using extracts of four novel plant species [Pittosporum undulatum, Melia azedarach, Schinus molle, and Syzygium paniculatum (var. australe)] using a "bottom-up approach" has been implemented for hexavalent chromium remediation. Nanoparticle characterizations show that different plant extracts lead to the formation of nanoparticles with different sizes, agglomeration tendencies, and shapes but similar amorphous nature and elemental makeup. Hexavalent chromium removal is linked with the particle size and monodispersity. Nanoparticles with sizes between 5 and 15 nm from M. azedarach and P. undulatum showed enhanced chromium removal capacities (84.1-96.2%, respectively) when compared to the agglomerated particles of S. molle and S. paniculatum with sizes between 30 and 100 nm (43.7-58.7%, respectively) in over 9 h. This study has shown that the reduction of iron salts with plant extracts is unlikely to generate vast quantities of stable zero valent iron nanoparticles but rather favor the formation of iron oxide nanoparticles. In addition, plant extracts with higher antioxidant concentrations may not produce nanoparticles with morphologies optimal for pollutant remediation.

Involvement of metallothionein, homocysteine and B-vitamins in the attenuation of arsenic-induced uterine disorders in response to the oral application of hydro-ethanolic extract of Moringa oleifera seed: a preliminary study

The painful invasive chelation therapy makes it challenging to continue the prolonged treatment against arsenic toxicity. Hence, the significance of the present preliminary investigation was to explore a noninvasive treatment strategy against sodium arsenite (As³⁺) by the use of a hydroethanolic extract of Moringa oleifera (MO) seed. Arsenic treatment (10 mg/kg body-weight) in animals showed significant level of oxidative stress as evidenced by increased serum levels of malondialdehyde (MDA), conjugated dienes (CD) and reduced level of non-protein thiol (NPSH). A significant diminution in the activities of enzymatic antioxidants was noted in As³⁺-treated rats. As³⁺ treatment showed a lengthy phase of metestrous in animals followed by significantly diminished ovarian steroidogenesis, increased ovarian follicular degeneration and distortion of uterine tissue histomorphology. In addition, there was a significant depletion of Vitamin-B₉ (folate) and B₁₂ following As³⁺ ingestion. The levels of circulating TNF-α, homocysteine (Hcy), uterine-IL-6, and liver metallothionein (MT-1) were significantly elevated in arsenic treated rats. MO at a dose of 100 mg/kg body-weight could successfully mitigate the uterine ROS generation by maintaining the uterine antioxidant status in As³⁺- treated rats. This seed extract prevented the deterioration of As³⁺-mediated ovarian-steroidogenesis and ovarian and uterine histoarchitecture significantly. B₉ and B₁₂ levels were also improved following the ingestion of the MO extract in arsenicated animals. Elevation of Hcy, TNF-α and IL-6 was also prevented by this MO seed extract in As³⁺-treated rats. A further increase of MT-1 level was achieved after MO ingestion in As³⁺-treated rats. Here, the alleviation of arsenic toxicity might involve via the regulation of the components of S-adenosine methionine (SAM) pool and MT-1.

Detection of arsenic-binding siderophores in arsenic-tolerating Actinobacteria by a modified CAS assay

The metalloid arsenic is highly toxic to all forms of life, and in many countries decontamination of water and soil is still required. Some bacteria have mechanisms to detoxify arsenic and can live in its presence. Actinobacteria are well known for their ability to produce a myriad of biologically-active compounds. In the present study, we isolated arsenic-tolerant Actinobacteria from contaminated water in Saxony, Germany, and determined their ability to produce siderophores able to bind arsenic. The binding capacity of different siderophore-like compounds was determined by a modified chrome azurol S (As-_mCAS) assay with As(III) at high pH and using CAS decolorization as a readout. Arsenic-tolerant isolates from three actinobacterial genera were identified by 16 S rRNA gene sequence analysis: Rhodococcus, Arthrobacter and Kocuria. The isolated Actinobacteria showed a high As(III)-binding activity by siderophore-like compounds, resulting in 82-100% CAS decolorization, as compared to the results with EDTA. The interaction between As(III) and siderophore-like compounds was also detected at neutral pH. In summary, our results suggest that the isolated arsenic-tolerant Actinobacteria produce siderophores that bind arsenic, and open new perspectives on potential candidates for decontaminating environments with arsenic and for other biotechnological applications.

A Perspective - can copper complexes be developed as a novel class of therapeutics?

Although copper-ligand complexes appear to be promising as a new class of therapeutics, other than the family of copper(ii) coordination compounds referred to as casiopeínas these compounds have yet to reach the clinic for human use. The pharmaceutical challenges associated with developing copper-based therapeutics will be presented in this article along with a discussion of the potential for high-throughput chemistry, computer-aided drug design, and nanotechnology to address the development of this important class of drug candidates.

Liposomal Curcumin Attenuates the Incidence of Oxidative Stress, Inflammation, and DNA Damage Induced by Copper Sulfate in Rat Liver

Background

Copper is an essential element that is used widely in agriculture as fungicides and insecticides; for example, it is used to control schistosomiasis and as an antiseptic and germicide. Copper sulfate (CuSO₄) induces multiorgan dysfunction through the stimulation of reactive oxygen species and oxidative stress. Despite the numerous pharmacological effects of curcumin (CUR), its pharmacokinetic properties are less promising. Hence, there is an urgent need for novel, effective strategies to attenuate heavy metal toxicity and consequently improve the treatment efficiency. Liposomal curcumin (L-CUR) improves the dissolution, stability, and bioavailability of treatment agents. This study compared the efficacy of CUR and L-CUR with that of desferrioxamine (DES), which is a heavy metal chelator against CuSO₄ hepatotoxicity.

Methods

All treatments with the aforementioned antioxidants were administered for 7 days along with CuSO₄. Serum levels of alanine aminotransferase, aspartate transaminase, lactate dehydrogenase, and C-reactive protein, hepatic nitric oxide (NO), and lipid peroxides (malondialdehyde) were measured; protein expression of cyclooxygenase 2 and DNA fragmentation were evaluated. Histopathological examinations were also conducted.

Results

A toxic dose of CuSO₄ induced elevations in the previously measured parameters; these increases were reduced by the tested antioxidants, whereas glutathione (GSH) and superoxide dismutase (SOD) levels were decreased. Treatment with the antioxidants in question modulated these levels. Liposomal CUR has more hepatoprotective efficiency than CUR, and its efficacy was similar to that of DES. The histopathological examinations confirmed these results.

Conclusions

Liposomal CUR may be useful for the prevention of CuSO₄-induced liver injury. Cyclooxygenase 2 protein expression and DNA fragmentation were involved in CuSO₄ toxicity and treatment.

Polyphenol composition and antioxidant properties of vegetable leaf-fortified bread

The aim of this work was to determine the antioxidant properties of aqueous extracts of vegetable leaf-fortified bread as well as estimate the contents of polyphenolic compounds. Enriched bread was produced from wheat flour fortified at 1, 2, and 3% (w/w) with dried leafy vegetable powders from Amaranthus viridis, Solanum macrocarpon, and Telfairia occidentalis. Gallic acid was the most abundant soluble polyphenol in the control bread and the content in the control bread was significantly higher (p < 0.05) than in all the fortified bread samples. Fortification of bread especially at 3% level resulted in significantly (p < 0.05) higher concentrations of other polyphenols (myricetin, catechin, quercetin, and rutin) compared to the control bread. The fortified bread extracts had significantly (p < 0.05) more effective antioxidants than the control for DPPH radical scavenging activity, ferric iron reducing antioxidant power, metal chelation, and inhibition of linoleic acid peroxidation. PRACTICAL APPLICATIONS: Bread is one of the consumed foods and could be used as a suitable carrier of bioactive compounds. Leafy vegetables contain high levels of polyphenols that could provide beneficial effects by contributing to improved health status of consumers. Therefore, incorporation of leafy vegetables into leavened bread could provide a means of enhancing polyphenol consumption. In this work, we showed that soluble polyphenols were enriched in vegetable-fortified bread. The polyphenol-rich extracts of the fortified bread demonstrated better free radical scavenging and inhibition of unsaturated fatty acid oxidation activities than the regular bread. Therefore, regular consumption of vegetable leaf-fortified bread could lead to reduced oxidative stress and associated chronic diseases in human beings. The vegetable leaf fortification could also serve as a suitable means of enhancing the shelf life of wheat bread.

Acetyl-L-Carnitine Attenuates Arsenic-Induced Oxidative Stress and Hippocampal Mitochondrial Dysfunction

Augmentation of mitochondrial oxidative stress through activating a series of deadly events has implicated as the main culprit of arsenic toxicity and therapeutic approaches based on improving mitochondrial function hold a great promise for attenuating the arsenic-induced toxicity. Acetyl-L-carnitine (ALC) through balancing the coenzyme A (CoA)/acyl-CoA ratio plays an important role in mitochondrial metabolism and thereby can help protect hippocampal neurons from oxidative damage. In the present study, we aimed to explore the effect of arsenic interactions on the mitochondrial function in the hippocampus of rats. Rats were randomly divided into five groups of control (distilled water), sodium arsenite (NaAsO₂, 20 mg/kg), and co-treatment of NaAsO₂ with various doses of ALC in three groups (100, 200, 300 mg/kg) and were treated orally for 21 consecutive days. Our results point out that arsenic exposure caused oxidative stress in rats' hippocampus, which led to the reactive oxygen species (ROS) generation, mitochondrial swelling, the collapse of the mitochondrial membrane potential, and release of cytochrome c. It also altered Bcl-2/Bax expression ratio and increased caspase-3 and caspase-9 activities. Furthermore, arsenic exposure via activation of NF-κB and microglia increased inflammation. ALC could concentration-dependently counteract the arsenic-induced oxidative stress, modulate the antioxidant defense capacity, and improve mitochondrial functions. In addition, ALC decreased the expression of both death-associated proteins and of inflammatory markers. These findings indicate that ALC improved the arsenic-induced hippocampal mitochondrial dysfunction which underlines the importance of ALC in providing a possible therapeutic strategy for the prevention of arsenic-induced neurodegeneration.

Collagen Prolyl 4-Hydroxylase as a Therapeutic Target

Collagen is the dominant protein of the extracellular matrix. Its distinguishing feature is a three-stranded helix of great tensile strength. (2 S,4 R)-4-Hydroxyproline residues are essential for the stability of this triple helix. These residues arise from the post-translational modification of (2 S)-proline residues by collagen prolyl 4-hydroxylases (CP4Hs), which are members of the Fe(II)- and α-ketoglutarate (AKG)-dependent dioxygenase family. Here, we provide a framework for the inhibition of CP4Hs as the basis for treating fibrotic diseases and cancer metastasis. We begin with a summary of the structure and enzymatic reaction mechanism of CP4Hs. Then, we review the metal ions, metal chelators, mimetics of AKG and collagen strands, and natural products that are known to inhibit CP4Hs. Our focus is on inhibitors with potential utility in the clinic. We conclude with a prospectus for more effective inhibitors.

Lead and cadmium excretion in feces and urine of children from polluted townships near a lead-zinc mine in Kabwe, Zambia

Lead (Pb) and cadmium (Cd) are toxic metals that exist ubiquitously in the environment. Children in polluted areas are particularly vulnerable to metal exposure, where clinical signs and symptoms could be nonspecific. Absorbed metals are excreted primarily in urine and reflect exposure from all sources. We analyzed Pb and Cd concentrations in blood, feces and urine of children from polluted townships near a lead-zinc mine in Kabwe, Zambia, to determine concurrent childhood exposure to the metals. Moreover, the study determined the Pb and Cd relationships among urine, feces and blood as well as accessed the potential of urine and fecal analysis for biomonitoring of Pb and Cd exposure in children. Fecal Pb (up to 2252 mg/kg, dry weight) and urine Pb (up to 2914 μg/L) were extremely high. Concentrations of Cd in blood (Cd-B) of up to 7.7 μg/L, fecal (up to 4.49 mg/kg, dry weight) and urine (up to 18.1 μg/L) samples were elevated. metal levels were higher in younger children (0-3 years old) than older children (4-7). Positive correlations were recorded for Pb and Cd among blood, urine and fecal samples whereas negative correlations were recorded with age. These findings indicate children are exposed to both metals at their current home environment. Moreover, urine and feces could be useful for biomonitoring of metals due to their strong relationships with blood levels. There is need to conduct a clinical evaluation of the affected children to fully appreciate the health impact of these metal exposure.

A Bis-Triazacyclononane Tris-Pyridyl N9 -Azacryptand "Beer Can" Receptor for Complexation of Alkali Metal and Lead(II) Cations

A new bis-triazacyclononane tris-pyridyl N₉ -azacryptand ligand is prepared via a convenient one-pot [2+3] condensation reaction between triazacyclononane and 2,6-bis(bromomethyl) pyridine in the presence of M₂ CO₃ (M=Li, Na, K). The proton, lithium, sodium, potassium and lead(II) complexes of the ligand are characterised in the solid state. Preliminary solution-phase competition experiments indicate that the cryptand ligand preferentially binds lead(II) in the presence of sodium, calcium, potassium and zinc cations in methanol solution.

Functionalized Fiber End Superstructure Fiber Bragg Grating Refractive Index Sensor for Heavy Metal Ion Detection

We present a novel superstructure fiber Bragg grating fiber end sensor capable of detecting variations in refractive index (RI) of liquids and potentially that of gases, and demonstrated an application in the detection of heavy metal ions in water. The sensor is capable of sensing RI variations in the range of 1.333 to 1.470 with good sensitivity of up to 230 dB/RIU achieved for the RI range of 1.370 to 1.390. The sensor is capable of simultaneously measuring variations in ambient temperature along with RI. A simple chemical coating was employed as a chelating agent for heavy metal ion detection at the fiber end to demonstrate an possible application of the sensor. The coated fiber sensor can conclusively detect the presence of heavy metal ions with concentrations upwards of 100 ppm. RI sensing capability of the sensor is neither affected by temperature nor strain and is both robust and easily reproducible.

A facile synthesis of cysteine-based diketopiperazine from thiol-protected precursor

l-Cysteine is one of the most promising biomass-based building blocks with great potential applications. Herein, we report a versatile synthetic route to produce cysteine-based 2,5-diketopiperazine (DKP) with good yield from the thiol-ene click reaction of l-cysteine and commercially available acrylates, followed by dimerization of the amino acid intermediates. The achieved DKP diastereomers were successfully separated and fully characterized by spectroscopic methods. Moreover, the chiroptical property of DKP in the presence of various metal ions was investigated by circular dichroism spectroscopy. The potential application of the optically active cysteine-based DKP as a chiral probe for detection of silver ion in water has been demonstrated.

Toxicodynamics of Lead, Cadmium, Mercury and Arsenic- induced kidney toxicity and treatment strategy: A mini review

Environmental pollution has become a concerning matter to human beings. Flint water crisis in the USA pointed out that pollution by heavy metal is getting worse day by day, predominantly by Lead, Cadmium, Mercury and Arsenic. Despite of not having any biological role in flora and fauna, they exhibit detrimental effect following exposure (acute or chronic). Even at low dose, they affect brain, kidney and heart. Oxidative stress has been termed as cause and effect in heavy metal-induced kidney toxicity. In treatment strategy, different chelating agent, vitamins and minerals are included, though chelating agents has been showed different fatal drawbacks. Interestingly, plants and plants derived compounds had shown possible effectiveness against heavy metals induced kidney toxicity. This review will provide detail information on toxicodynamics of Pb, Cd, Hg and As, treatment strategy along with the possible beneficiary role of plant derived compound to protect kidney.

Association between heavy metal levels and acute ischemic stroke

Background

Few studies have examined the relationship between the amounts of heavy metal and stroke incidence. The aim of this study was to explore the relationship between levels of heavy metals, including Pb, Hg, As, and Cd, in patients with acute ischemic stroke (AIS).

Methods

We selected patients with first-ever AIS onset within 1 week as our study group. Healthy controls were participants without a history of stroke or chronic disease, except hypertension. The serum levels of Pb, Hg, As, and Cd in participants in the experimental and control groups were determined. All participants received a 1-g infusion of edetate calcium disodium (EDTA). Urine specimens were collected for 24 h after EDTA infusion and measured for heavy metal levels.

Results

In total, 33 patients with AIS and 39 healthy controls were enrolled in this study. The major findings were as follows: (1) The stroke group had a significantly lower level of serum Hg (6.4 ± 4.3 μg/L vs. 9.8 ± 7.0 μg/L, P = 0.032, OR = 0.90, 95% CI = 0.81–0.99) and a lower level of urine Hg (0.7 ± 0.7 μg/L vs. 1.2 ± 0.6 μg/L, P = 0.006, OR = 0.27, 95% CI = 0.11–0.68) than the control group. (2) No significant difference in serum Pb (S-Pb), As (S-As), and Cd (S-Cd) levels and urine Pb (U-Pb), As (U-As) and Cd (U-Cd) levels was observed in either group.

Conclusions

Our study found low levels of serum and urine Hg in first-ever patients with AIS, providing new evidence of dysregulated heavy metals in patients with AIS.

Electronic supplementary material

The online version of this article (10.1186/s12929-018-0446-0) contains supplementary material, which is available to authorized users.

Intracellular Transport of Silver and Gold Nanoparticles and Biological Responses: An Update

Medicine, food, and cosmetics represent the new promising applications for silver (Ag) and gold (Au) nanoparticles (NPs). AgNPs are most commonly used in food and cosmetics; conversely, the main applications of gold NPs (AuNPs) are in the medical field. Thus, in view of the risk of accidentally or non-intended uptake of NPs deriving from the use of cosmetics, drugs, and food, the study of NPs⁻cell interactions represents a key question that puzzles researchers in both the nanomedicine and nanotoxicology fields. The response of cells starts when the NPs bind to the cell surface or when they are internalized. The amount and modality of their uptake depend on many and diverse parameters, such as NPs and cell types. Here, we discuss the state of the art of the knowledge and the uncertainties regarding the biological consequences of AgNPs and AuNPs, focusing on NPs cell uptake, location, and translocation. Finally, a section will be dedicated to the most currently available methods for qualitative and quantitative analysis of intracellular transport of metal NPs.

Full Atrioventricular Block Secondary to Acute Poisoning Mercury: A Case Report

Background: The biological behaviour and clinical significance of mercury toxicity vary according to its chemical structure. Mercury differs in its degree of toxicity and in its effects on the nervous, digestive and immune systems as well as on organs such as the lungs, kidneys, skin, eyes and heart. Human exposure occurs mainly through inhalation of elemental mercury vapours during industrial and artisanal processes such as artisanal and small-scale gold mining. Case presentation: A 52-years-old female, housewife, with a body mass index of 25.3 kg/cm², without smoking or alcohol habits or any important clinical or chronic cardiovascular history, was admitted to the emergency room due to probable accidental poisoning by butane gas. Clinical manifestations with a headache, dizziness, cough, and dyspnoea of medium to small efforts. An initial physical exploration with Glasgow scored at 15, with arrhythmic heart sounds, pulmonary fields with bilateral subcrepitant rales and right basal predominance. Electrocardiographic findings were as follows: a cardiac frequency of 50 beats per minute and atrioventricular dissociation. Laboratory parameters were: white blood cells at 15.8 × 10⁸/L; aspartate aminotransferase at 38 U/L; lactate dehydrogenase at 1288 U/L; creatine-kinase at 115 U/L; CK-MB fraction at 28 U/L; and other biochemical parameters were within the reference values. A radiographic evaluation showed flow cephalization, diffuse bilateral infiltrates with right basal predominance. In addition, the patient presented data of low secondary expenditure to third-degree atrioventricular (AV) block for which the placement of a transvenous pacemaker was decided, substantially improving the haemodynamic parameters. Subsequently, after a family interrogation, the diagnosis of mercury inhalation poisoning was established. An initial detection of mercury concentration (Hg(0)) was carried out, reporting 243.5 µg/L. In view of this new evidence, mercury chelation therapy with intravenous calcium disodium ethylenediamine tetraacetic acid (CaNa₂·EDTA) was initiated. After 8-days of hospital stay, she presented a favourable evolution with both clinical and radiological improvements, so that the mechanical ventilation progressed to extubating. Subsequently, she was referred for cardiology because of her persistent 3rd-degree atrioventricular block, deciding to place a definitive bicameral pacemaker. The patient was discharged from the hospital 14 days after admission due to clinical improvements with mercury plasma levels at 5 µmol/L and a heart rhythm from the pacemaker. Conclusions: We show evidence that acute exposure to elemental mercury can affect the heart rhythm, including a complete atrioventricular blockage.

Lead: Tiny but Mighty Poison

The documentation of lead toxicity (plumbism) dates back to the times when man learnt its various applications. This versatile heavy metal is non-degradable and its ability to get accumulated in the body that goes undiagnosed, makes it a serious environmental health hazard. Lead is now known to affect almost every organ/tissue of the human body. With irreversible effects on neurobiological development of young children and foetus, its toxicity has lasting implications on the human life. Outlining the symptoms, diagnosis and treatment therapy for lead poisoning, the present review elaborates the pathophysiological effects of lead on various organs. This will be of immense help to the health professionals so as to inculcate a better understanding of the lead poisoning which otherwise is asymptomatic. With chelation therapy being the classic path of treatment, new strategies are being explored as additive/adjunct therapy. It is now understood that lead toxicity is completely preventable. In this regard significant efforts are in place in the developed countries whereas much needs to be done in the developing countries. Spreading the awareness amongst the masses by educating them and reducing the usage of lead following stricter industry norms appears to be the only roadmap to prevent lead poisoning. Efforts being undertaken by the Government of India and other organisations are also mentioned.

Changes in the brain antioxidant profile after chronic vanadium administration in mice

Vanadium is known to induce reactive oxygen species (ROS) in biological systems. Exposure to vanadium has been linked to neurological defects affecting the central nervous system (CNS) early in life and culminates later to neurodegeneration. This study was designed to evaluate the effects of chronic vanadium exposure on antioxidant profile in mice, and progressive changes after withdrawal from treatment. A total of 85 male BALB/c mice (4 weeks old) were used for the experiment and were divided into three groups of vanadium exposed (3 mg/kg i.p at 3-18 months treatment), matched controls, and animals exposed to vanadium for three months and thereafter vanadium was withdrawn. Vanadium exposure caused significant increases (p<0.05) in levels of malondialdehyde (MDA), hydrogen peroxide (H₂O₂) generation and nitric oxide with a concomitant decrease (p<0.05) in the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione-S-transferase and a decline in the level of reduced glutathione (GSH) after 6 months of vanadium exposure in the brain. This trend continued in all vanadium-exposed groups (9, 12, 15 and 18 months) relative to the matched controls. Withdrawal after 3 months of vanadium exposure significantly reversed oxidative stress in intoxicated mice from 9 to 15 months after vanadium withdrawal. We have shown that chronic administration of vanadium led to oxidative stress in the brain which is reversible only after a long period of vanadium withdrawal.

Bioactive profiling and therapeutic potential of mushroom (Pleurotus tuberregium) extract on Wistar albino rats (Ratus norvegicus) exposed to arsenic and chromium toxicity

Mushroom species are valued in gourmet traditions around the world for their unique taste, aroma, nutritional value and medicinal potentials. The bioactive profiling of P. tuberregium mushroom was evaluated to determine it therapeutic effect on Wistar albino rats exposed to arsenic (As) and chromium (Cr) toxicity. Proximate analysis of P. tuberregium showed high composition of carbohydrate (80.24) followed by moisture (21.16), protein (11.46), ash (3.03) and fibre (0.25) content. Phytochemical analysis revealed the presence of polyphenols (2.58), alkaloid (2.46), oxalate (4.25), flavonoid (1.68), tannin (0.38) and Saponin (trace) in trace amount. Mineral analysis yielded variable amounts of Na, Mg, K and Ca. Therapeutics assessment of P. tuberregium to Wistar albino rats exposed to As-Cr toxicity showed improved feed and water intake during the exposure duration. Haematological indices revealed significant increase in platelet (PLT), granulocytes and monocytes while lymphocyte (LY) and red cell distribution width (RDW) were low. Biochemical and redox marker of liver and kidney profiles showed decrease in alkaline phosphatase (ALP), alanine transaminase (ALT) and aspartate transaminase (AST) in the liver. Creatinine and urea in the kidney also decrease while total protein increased significantly. Malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), glutathione S-transferase (GST) decrease in the liver and kidney of the therapeutic group when compared with As-Cr treated rats. The presence of alkaloids and flavonoids in significant amount may have contributed in the therapeutic changes observed in all the parameters. Therefore, our findings conclude that P. tuberregium possessed remarkable effect against As-Cr induced toxicity in albino rats and may be useful in metal toxicity treatment in man and may be concluded that they are therapeutically effective.

Combinatorial drug delivery strategy employing nano-curcumin and nano-MiADMSA for the treatment of arsenic intoxication in mouse

Chelation therapy is the mainstream treatment for heavy metal poisoning. Apart from this, therapy using antioxidant/herbal extracts are the other strategies now commonly being tried for the treatment. We have previously reported individual beneficial efficacy of nanoparticle mediated administration of an antioxidant like 'curcumin' and an arsenic chelator 'monoisoamyl 2,3-dimercaptosuccinic acid (MiADMSA)' for the treatment of arsenic toxicity compared to bulk drugs. The present paper investigates our hypothesis that a combination drug delivery therapy employing two nanosystems, a chelator and a strong antioxidant, may produce more pronounced therapeutic effects compared to individual effects in the treatment of arsenic toxicity. An in-vivo study was conducted wherein arsenic as sodium arsenite (100 ppm) was administered in drinking water for 5 months to Swiss albino mice. This was followed by a treatment protocol comprising of curcumin encapsulated chitosan nanoparticles (nano-curcumin, 15 mg/kg, orally for 1 month) either alone or in combination with MiADMSA encapsulated polymeric nanoparticles (nano-MiADMSA, 50 mg/kg for last 5 days) to evaluate the therapeutic potential of the combination treatment. Our results demonstrated that co-treatment with nano-curcumin and nano-MiADMSA provided beneficial effects in a synergistic way on the adverse changes in oxidative stress parameters and metal status induced by arsenic.

Protective activity of pyruvate against vanadium-dependent cytotoxicity in Chinese hamster ovary (CHO-K1) cells

With increasing human exposure to vanadium-containing compounds and growing concern over their impact on human health, identification of safe methods for efficient treatment of vanadium poisoning may be of value. In this study, using Chinese hamster ovary (CHO-K1) cells, we show that the toxicity of vanadyl sulphate (VOSO₄) is mitigated in the presence of sodium pyruvate. The exposure of CHO-K1 cells to 100 μM VOSO₄ for 48 h induced significant cytotoxicity (measured with a resazurin assay) and elevation of the contents of malondialdehyde (MDA), a lipid peroxidation product, in the examined cells. When added simultaneously with VOSO₄ to the culture medium, pyruvate (4.5 mM) reduced VOSO₄-mediated cytotoxicity by twofold and inhibited MDA formation. Phase-contrast microscopy confirmed that the general morphology of cell cultures treated with 100 μM VOSO₄ and 4.5 mM pyruvate was improved compared to VOSO₄-only treated cells. The two-way analysis of variance revealed that the reduction of the adverse effects of VOSO₄ in the presence of pyruvate was due to the independent action of pyruvate as well as antagonistic interaction between VOSO₄ and pyruvate. From these data, it can be concluded that the pyruvate treatment may play a beneficial role in reducing vanadium-triggered health hazards.

Ascorbic acid ameliorates lead-induced apoptosis in the cerebellar cortex of developing rats

We investigated the effects of the gestational administration of lead (Pb) and ascorbic acid on cerebellar development. Pregnant female rats were randomly assigned to the control, Pb, or Pb plus ascorbic acid (PA) groups; six offspring per cage were randomly selected for analysis. Compared to the control group, fewer Purkinje cells were observed in the Pb-exposed pups at postnatal day 21. However, co-administrating Pb and ascorbic acid inhibited the Pb-induced reduction in Purkinje cells. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining, which detected DNA fragmentation in the dying cells, showed more TUNEL-positive cells in the Pb group, while co-treatment with Pb and ascorbic acid mitigated the Pb-induced cellular degeneration. Using immunohistochemistry and immunoblotting, we additionally found that Pb exposure induced a rise in the apoptotic factor Bax in the cerebellum, while Pb plus ascorbic acid treatment ameliorated this Bax induction. Since, Pb competes with the iron in the cell and the accumulation of free iron triggers oxidative stress, we performed iron staining, which revealed that ascorbic acid prevented the Pb-induced rises in iron-reactive cells and iron-reactivity. The anti-oxidant enzyme manganese-dependent superoxide dismutase showed change patterns that were similar to those of iron in the cerebellum. Finally, the pups' blood Pb levels were highest in the Pb group but were reduced in the PA group. Our findings suggest that ascorbic acid effectively ameliorates Pb-induced apoptosis and oxidative stress in the cerebellum. The present results imply that ascorbic acid treatment during pregnancy may protect against Pb-mediated developmental impairments in the cerebellum.

Efficacy of N,N'bis-(2-mercaptoethyl) isophthalamide on mercury intoxication: a randomized controlled trial

BACKGROUND

Chronic mercury intoxication is a severe health issue and occurs especially in gold mining communities. Common chelators used for improving mercury elimination are not everywhere available and challenged by poor cell wall penetration. This study is part of a feasibility trial and the aim was to gather first information about the efficacy of the newly developed chelator N,N'bis-(2-mercaptoethyl) isophthalamide (NBMI) on chronic mercury intoxication.

METHODS

In this three-armed, placebo-controlled randomized trial, 36 miners with mercury urine levels exceeding 15 μg/l were administered 100 mg NBMI, 300 mg NBMI or placebo for 14 days. Levels of mercury in urine [μg/l and μg/g creatinine] and plasma l were analyzed. Therapeutic effect was assessed using the medical intoxication score (MIS) and its single health outcomes (e.g. excessive salivation, sleeping problems), fatigue scores, a neuromotoric test battery (CATSYS) and a neurological outcome (Finger to nose test).

RESULTS

Physical fatigue was significantly decreased in the 300 mg NBMI group compared to the control. Mercury concentration in urine following 300 mg NBMI treatment was significantly lowered compared to control, however, this effect was less distinct with adjustment for creatinine.

CONCLUSION

NBMI showed an effect on physical fatigue and there were indications to positive effects on other symptoms as well. More comprehensive studies are mandatory to verify the effects of NBMI as a novel tool for treating mercury intoxications.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02486289 . Date of registration: June 24, 2015.