Chelation in metal intoxication

Inhalation of Silver Silicate Nanoparticles Leads to Transient and Differential Microglial Activation in the Rodent Olfactory Bulb

Engineered silver nanoparticles (AgNPs), including silver silicate nanoparticles (Ag-SiO₂ NPs), are used in a wide variety of medical and consumer applications. Inhaled AgNPs have been found to translocate to the olfactory bulb (OB) after inhalation and intranasal instillation. However, the biological effects of Ag-SiO₂ NPs and their potential nose-to-brain transport have not been evaluated. The present study assessed whether inhaled Ag-SiO₂ NPs can elicit microglial activation in the OB. Adult Sprague-Dawley rats inhaled aerosolized Ag-SiO₂ NPs at a concentration of 1 mg/ml for 6 hours. On day 0, 1, 7, and 21 post-exposure, rats were necropsied and OB were harvested. Immunohistochemistry on OB tissues were performed with anti-ionized calcium-binding adapter molecule 1 and heme oxygenase-1 as markers of microglial activation and oxidative stress, respectively. Aerosol characterization indicated Ag-SiO₂ NPs were sufficiently aerosolized with moderate agglomeration and high-efficiency deposition in the nasal cavity and olfactory epithelium. Findings suggested that acute inhalation of Ag-SiO₂ NPs elicited transient and differential microglial activation in the OB without significant microglial recruitment or oxidative stress. The delayed and differential pattern of microglial activation in the OB implied that inhaled Ag-SiO₂ may have translocated to the central nervous system via intra-neuronal pathways.

Comparative study of PMS oxidation with Fenton oxidation as an advanced oxidation process for Co-EDTA decomplexation

In nuclear industry, Co-EDTA complex is generated due to the decontamination activities of nuclear power plants (NPPs). This complex is extremely refractory to the convention methods and can escalate the mobility of Co radionuclide in the environment. Due to its hazardous impact on human and environment, the effective treatments of Co-EDTA complexes are highly recommended. In this study, for the first time, we applied both hydroxyl (OH) and sulfate radical (SO₄^-) based advanced oxidation processes (AOPs) namely Fenton and peroxymonosulfate (PMS) reactions for the Co-EDTA decomplexation. Both reactions exhibited higher Co-EDTA decomplexation at pH = 3, however, the PMS based reaction was found to be superior, which showed highest decomplexation efficiency (without pH adjustment) over Fenton reaction (pH = 1-13). Moreover, PMS based system was found to be more suitable than Fenton reaction, because PMS showed best Co-EDTA decomplexation efficiency without any additional catalyst dosages at the shorter reaction time. XRD data confirmed the presence of both CoO and Co(OH)₂ in the precipitates after treatment. The electron spin resonance spectroscopy (ESR) analysis identified OH and SO₄^- in Fenton and PMS system, respectively. From this study, we believe that PMS based reaction is a superior alternative of Fenton reaction for the Co-EDTA decomplexation.

Effect of 0.2% Chitosan Associated with Different Final Irrigant Protocols on the Fiber Post Bond Strength to Root Canal Dentin of Bovine Teeth: An In-vitro Study

Objective:

This in-vitro study investigated the effect of 0.2% Chitosan associated with different final irrigant protocols on the bond strength of fiber posts (FP) to root canal dentin.

Methods:

Fifty bovine incisors roots were prepared using the ProTaper Universal system, irrigated with 2.5% sodium hypochlorite, and divided into one control group (n=10) with no final irrigant protocol and four experimental groups (n=10), which were defined according to the combination of chelating solution (17% EDTA and 0.2% Chitosan) and irrigant activation/delivery method [conventional irrigation (CI), and passive ultrasonic irrigation (PUI)]. Post spaces were prepared to a depth of 12 mm using #1-5 Largo drills, and the FP were cemented using self-adhesive resin cement. Two slices of 2 mm in thickness from each third were obtained and submitted to the micropush-out test. After testing the push-out strength, the slices were analyzed under a stereomicroscope at 40× magnification for bond failure patterns determination. Statistical analysis was performed using three-way ANOVA followed by Tukey’s test (α = 0.05).

Results:

The control and 17% EDTA + CI groups exhibited significantly lower bond strength than 0.2% Chitosan + CI, 17% EDTA + PUI, and 0.2% Chitosan + PUI groups in the cervical third (P = 0.00). The cervical third had higher values than the middle and apical thirds in control (P = 0.00), 17% EDTA + PUI (P = 0.00), and 0.2% Chitosan + PUI groups (P = 0.00). Adhesive cement-dentin failure type was predominant in all groups.

Conclusion:

The use of 0.2% chitosan did not affect the bond strength of FP to root dentin. Passive ultrasonic activation of chelating solutions resulted in an improvement in bonding strength.

Use of tetrasodium EDTA acid for the treatment of intraluminal obstruction of subcutaneous ureteral bypass devices

OBJECTIVES

The aim of this study was to evaluate the efficacy and tolerability of a 4% tetrasodium EDTA (tEDTA) infusion protocol in the subcutaneous ureteral bypass (SUB) devices of cats with intraluminal obstruction at a veterinary teaching hospital between July 2017 and April 2020.

METHODS

This was a retrospective controlled study. Cats with an obstructed SUB device underwent a 4% tEDTA infusion protocol. Obstruction of the device was diagnosed based on renal pelvic dilation, dilatation of the ureter, mineralized material within the device (cystostomy or nephrostomy catheters) seen on ultrasound, the absence of visible bubbles within the renal pelvis and/or urinary bladder following ultrasound-guided flushing of the device with saline.

RESULTS

A total of 16 tEDTA infusion protocols were performed in 14 cats. The infusion protocol was considered successful in 11/16 SUB devices (68.8%). Six devices (n = 6/11; 54.5%) had recurrence of obstruction with a median time of 87 days. One or more episodes of self-limiting pollakiuria and/or hematuria following infusion was seen in eight patients (n = 8/14; 57.1%).

CONCLUSIONS AND RELEVANCE

Infusions of 4% tEDTA successfully relieved intraluminal obstruction in patients with occluded SUB devices; however, the recurrence of obstruction was common. Additional studies evaluating case selection and optimal protocols are warranted.

Application and validation of a biotic ligand model for calculating acute toxicity of lead to Moina dubia in lakes of Hanoi, Vietnam

It is increasingly being recognized that biotic ligand models (BLMs) can successfully predict the toxicity of divalent metals toward aquatic biota applied to temperate freshwater ecosystems. However, studies on the eutrophic lakes in tropical regions toward native tropical organisms, including Moina, are relatively limited. In this study, Moina dubia, the native organism of the Hanoi eutrophic urban lakes, were used in toxicological studies of lead (Pb); 24-h EC₅₀ value of Pb was 523.19 µg/L under optimal living conditions for M. dubia in the laboratory. The constant binding of Pb²⁺ on M. dubia surface sites (log K_PbBL = 2.38) was significantly low. Other stability constants were obtained under experiments as logK_CaBL = 2.48, logK_MgBL = 2.80, logK_NaBL = 2.35, logK_KBL = 2.49, and logK_HBL = 3.026. A BLM was developed to calculate the acute toxicity (EC₅₀-24 h) of lead on M. dubia based on the condition of the urban lakes of Hanoi. Validation with toxicity data in synthetic medium showed a coefficient determination of 79.16% and a mean absolute percentage error (MAPE) of 10.2%, while the validation with the toxicity data with natural water medium from 11 Hanoi lakes showed a coefficient determination of 73.7% and a MAPE of 13.66%. The BLM worked well with water at a pH of 7.0 to 8.0, but failed with water at a pH above 8.0. Eutrophic conditions proved to have a significant effect on the toxicity of lead on local zooplankton.

Imaging of Transmetallation and Chelation Phenomena Involving Radiological Contrast Agents in Mineral-Rich Fruits

Exogenous heavy metals or non-metallic waste products, for example lanthanide or iodinated contrast media for radiological procedures, may interfere with the biochemical pools in patients and in common food sources, creating an excess buildup of exogenous compounds which may reach toxic levels. Although the mechanisms are unknown, our experiments were designed to test if this toxicity can be attributed to “transmetallation” or “chelation” reactions freeing up lanthanides or chelated transition metals in acidic fruits used as phantoms representing the biologically active and mineral-rich carbohydrate matrix. The rapid breakdown of stable contrast agents have been reported at a lower pH. The interaction of such agents with native metals was examined by direct imaging of contrast infused fresh apples and sweet potatoes using low energy X-rays (40–44 kVp) and by magnetic resonance imaging at 1.5 and 3T. The stability of the exogenous agents seemed to depend on endogenous counterions and biometals in these fruits. Proton spin echo MR intensity is sensitive to paramagnetic minerals and low energy X-ray photons are sensitively absorbed by photoelectric effects in all abundant minerals and were compared before and after the infusion of radiologic contrasts. Endogenous iron and manganese are believed to accumulate due to interactions with exogenous iodine and gadolinium in and around the infusion spots. X-ray imaging had lower sensitivity (detection limit approximately 1 part in 10⁴), while MRI sensitivity was two orders of magnitude higher (approximately 1 part in 10⁶), but only for paramagnetic minerals like Mn and Fe in our samples. MRI evidence of such a release of metal ions from the native pool implicates transmetallation and chelation reactions that were triggered by infused contrast agents. Since Fe and Mn play significant roles in the function of metalloenzymes, our results suggest that transmetallation and chelation could be a plausible mechanism for contrast induced toxicity in vivo.

Phytochemicals in the Management of Arsenic Toxicity

Arsenic toxicity is a major concern due to its deleterious consequences for human health. Rapid industrialization also has weakened the quality of the environment by introducing pollutants that may disrupt balanced ecosystems, adversely and irreversibly impacting humans, plants, and animals. Arsenic, an important toxicant among all environmental hazards, can lead to several detrimental effects on cells and organs, impacting the overall quality of life. Nevertheless, arsenic also has a rich history as a chemotherapeutic agent used in ancient days for the treatment of diseases such as malaria, cancer, plague, and syphilis when other chemotherapeutic agents were yet to be discovered. Arsenicosis-mediated disorders remain a serious problem due to the lack of effective therapeutic options. Initially, chelation therapy was used to metabolically eliminate arsenic by forming a complex, but adverse effects limited their pharmacological use. More recently, plant-based products have been found to provide significant relief from the toxic effects of arsenic poisoning. They act by different mechanisms affecting various cellular processes. Phytoconstituents such as curcumin, quercetin, diallyl trisulfide, thymoquinone, and others act via various molecular pathways, primarily by attenuating oxidative damage, membrane damage, DNA damage, and proteinopathies. Nonetheless, most of the phytochemicals reviewed here protect against the adverse effects of metal or metalloid exposure, supporting their consideration as alternatives to chelation therapy. These agents, if used prophylactically and in conjunction with other chemotherapeutic agents, may provide an effective approach for management of arsenic toxicity. In a few instances, such strategies like coadministration of phytochemicals with a known chelating agent have led to more pronounced elimination of arsenic from the body with lesser off-site adverse effects. This is possible because combination treatment ensures the use of a reduced dose of chelating agent with a phytochemical without compromising treatment. Thus, these therapies are more practical than conventional therapeutic agents in ameliorating arsenic-mediated toxicity. This review summarizes the potential of phytochemicals in alleviating arsenic toxicity on the basis of available experimental and clinical evidence.

Effects of Sodium Pyruvate on Vanadyl Sulphate-Induced Reactive Species Generation and Mitochondrial Destabilisation in CHO-K1 Cells

Vanadium is ranked as one of the world’s critical metals considered important for economic growth with wide use in the steel industry. However, its production, applications, and emissions related to the combustion of vanadium-containing fuels are known to cause harm to the environment and human health. Pyruvate, i.e., a glucose metabolite, has been postulated as a compound with multiple cytoprotective properties, including antioxidant and anti-inflammatory effects. The aim of the present study was to examine the antioxidant potential of sodium pyruvate (4.5 mM) in vanadyl sulphate (VOSO₄)-exposed CHO-K1 cells. Dichloro-dihydro-fluorescein diacetate and dihydrorhodamine 123 staining were performed to measure total and mitochondrial generation of reactive oxygen species (ROS), respectively. Furthermore, mitochondrial damage was investigated using MitoTell orange and JC-10 staining assays. We demonstrated that VOSO₄ alone induced a significant rise in ROS starting from 1 h to 3 h after the treatment. Additionally, after 24 and 48 h of exposure, VOSO₄ elicited both extensive hyperpolarisation and depolarisation of the mitochondrial membrane potential (MMP). The two-way ANOVA analysis of the results showed that, through antagonistic interaction, pyruvate prevented VOSO₄-induced total ROS generation, which could be observed at the 3 h time point. In addition, through the independent action and antagonistic interaction with VOSO₄, pyruvate provided a pronounced protective effect against VOSO₄-mediated mitochondrial toxicity at 24-h exposure, i.e., prevention of VOSO₄-induced hyperpolarisation and depolarisation of MMP. In conclusion, we found that pyruvate exerted cytoprotective effects against vanadium-induced toxicity at least in part by decreasing ROS generation and preserving mitochondrial functions

Protective Role of the Essential Trace Elements in the Obviation of Cadmium Toxicity: Glimpses of Mechanisms

Cadmium (Cd) is toxic non-essential heavy metal that precipitates adverse health effects in humans and animals. Chelation therapy, the typical treatment for cadmium toxicity, has certain safety and efficacy issues to treat long term cadmium toxicity, in particular. Recent studies have shown that essential trace elements can play important roles in obviating experimental Cd toxicity. This study organizes and reviews the prototypical evidences of the protective effects of essential trace elements against Cd toxicity in animals and attempts to point out the underlying mechanisms. Zinc, selenium, iron, and combinations thereof are reported to be active. The major mechanisms elucidated inter alia are-induction of metallothionein (MT) synthesis and Cd-MT binding (for zinc), modulation of oxidative stress and apoptosis, interference in cadmium absorption and accumulation from body-thereby maintenance of essential metal homeostasis and cytoprotection. Based on the findings, essential trace elements can be recommended for the susceptible population. The application of these trace elements appears beneficial for both the prevention and remediation of long-term Cd toxicity operative via multiple mechanisms with no or minimal adverse effects as compared to the conventional chelation therapy.

High Photoluminescence Polyindole/CuInS Quantum Dots for Pb Ions Sensor

Polyindole is considered an excellent conducting polymer with interested properties for different applications. A novel polyindole (PIn)/CuInS (CIS)/ZnS quantum dots (QDs) nanocomposite was synthesized via in situ polymerization of PIn in presence of CIS/ZnS QDs. By investigating the effect of CIS/ZnS QDs on optical properties of PIn, it was found that the optical band gaps of PIn, CIS/ZnS QDs, and PIn/CIS/ZnS QDs nanocomposite were 3.24 eV, 4.68 eV and 3.44 eV, respectively. From the luminance spectra, it was observed that emission peaks of PIn at 442 and 468 nm are independent of the excitation wavelength with the highest intensity at excitation wavelength of 380 nm. However, the luminance spectrum of PIn/CIS/ZnS QDs nanocomposite exhibited a quenching peak for CIS/ZnS QDs while the intensity of PIn peak was enhanced. High resolution of transmission electron microscope image of CIS/ZnS QDs revealed nanocrystals with a size of 3–4.5 nm and lattice space of 0.2 nm. PIn/CIS/ZnS QDs nanocomposite as the fluorescent probe was employed for sensing different concentrations of Pb2+ from 5 to 50 ppb. The reaction between PIn/CIS/ZnS QDs and Pb2+ was slightly quenched and fixed after 90 min. The emission peak was reduced gradually with increasing concentration of lead via photo-induced electron transfer or ion exchange mechanism. The value of correlation coefficient (R2) was 0.99, the sensitivity was 0.0041 ppb−1 and limit of detection value was 4.48 ppb.

Disulfiram enhances meropenem activity against NDM- and IMP-producing carbapenem-resistant Acinetobacter baumannii infections

OBJECTIVES

To evaluate the in vitro and in vivo efficacy of the FDA-approved drug disulfiram in combination with meropenem against MBL-expressing carbapenem-resistant Acinetobacter baumannii.

METHODS

Chequerboard and antibiotic resistance reversal analysis were performed using 25 clinical isolates producing different MBLs. Three representative strains harbouring NDM, IMP or non-MBL genes were subjected to a time-kill assay to further evaluate this synergistic interaction. Dose-dependent inhibition by disulfiram was assessed to determine IC50 for NDM-1, IMP-7, VIM-2 and KPC-2. Further, to test the efficacy of meropenem monotherapy and meropenem in combination with disulfiram against NDM- and IMP-harbouring A. baumannii, an experimental model of systemic infection and pneumonia was developed using BALB/c female mice.

RESULTS

Chequerboard and antibiotic reversal assay displayed a synergistic interaction against MBL-expressing A. baumannii strains with 4- to 32-fold reduction in MICs of meropenem. In time-kill analysis, meropenem and disulfiram exhibited synergy against NDM- and IMP-producing carbapenem-resistant A. baumannii (CRAb) isolates. In vitro dose-dependent inhibition analysis showed that disulfiram inhibits NDM-1 and IMP-7 with IC50 values of 1.5 ± 0.6 and 16.25 ± 1.6 μM, respectively, with slight or no inhibition of VIM-2 (<20%) and KPC-2. The combination performed better in the clearance of bacterial load from the liver and spleen of mice infected with IMP-expressing CRAb. In the pneumonia model, the combination significantly decreased the bacterial burden of NDM producers compared with monotherapy.

CONCLUSIONS

These results strongly suggest that the combination of disulfiram and meropenem represents an effective treatment option for NDM- and IMP-associated CRAb infections.

Renal hypoxia-HIF-PHD-EPO signaling in transition metal nephrotoxicity: friend or foe?

The kidney is the main organ that senses changes in systemic oxygen tension, but it is also the key detoxification, transit and excretion site of transition metals (TMs). Pivotal to oxygen sensing are prolyl-hydroxylases (PHDs), which hydroxylate specific residues in hypoxia-inducible factors (HIFs), key transcription factors that orchestrate responses to hypoxia, such as induction of erythropoietin (EPO). The essential TM ion Fe is a key component and regulator of the hypoxia–PHD–HIF–EPO (HPHE) signaling axis, which governs erythropoiesis, angiogenesis, anaerobic metabolism, adaptation, survival and proliferation, and hence cell and body homeostasis. However, inadequate concentrations of essential TMs or entry of non-essential TMs in organisms cause toxicity and disrupt health. Non-essential TMs are toxic because they enter cells and displace essential TMs by ionic and molecular mimicry, e. g. in metalloproteins. Here, we review the molecular mechanisms of HPHE interactions with TMs (Fe, Co, Ni, Cd, Cr, and Pt) as well as their implications in renal physiology, pathophysiology and toxicology. Some TMs, such as Fe and Co, may activate renal HPHE signaling, which may be beneficial under some circumstances, for example, by mitigating renal injuries from other causes, but may also promote pathologies, such as renal cancer development and metastasis. Yet some other TMs appear to disrupt renal HPHE signaling, contributing to the complex picture of TM (nephro-)toxicity. Strikingly, despite a wealth of literature on the topic, current knowledge lacks a deeper molecular understanding of TM interaction with HPHE signaling, in particular in the kidney. This precludes rationale preventive and therapeutic approaches to TM nephrotoxicity, although recently activators of HPHE signaling have become available for therapy.

Comparative Effects of Deferiprone and Salinomycin on Lead-Induced Disturbance in the Homeostasis of Intrarenal Essential Elements in Mice

Lead (Pb) exposure induces severe nephrotoxic effects in humans and animals. Herein, we compare the effects of two chelating agents, salinomycin and deferiprone, on Pb-induced renal alterations in mice and in the homeostasis of essential elements. Adult male mice (Institute of Cancer Research (ICR)) were randomized into four groups: control (Ctrl)—untreated mice administered distilled water for 28 days; Pb-exposed group (Pb)—mice administered orally an average daily dose of 80 mg/kg body weight (BW) lead (II) nitrate (Pb(NO₃)₂) during the first two weeks of the experimental protocol followed by the administration of distilled water for another two weeks; salinomycin-treated (Pb + Sal) group—Pb-exposed mice, administered an average daily dose of 16 mg/kg BW salinomycin for two weeks; deferiprone-treated (Pb + Def) group—Pb-exposed mice, administered an average daily dose of 20 mg/kg BW deferiprone for 14 days. The exposure of mice to Pb induced significant accumulation of the toxic metal in the kidneys and elicited inflammation with leukocyte infiltrations near the glomerulus. Biochemical analysis of the sera revealed that Pb significantly altered the renal function markers. Pb-induced renal toxicity was accompanied by a significant decrease in the endogenous renal concentrations of phosphorous (P), calcium (Ca), copper (Cu) and selenium (Se). In contrast to deferiprone, salinomycin significantly improved renal morphology in Pb-treated mice and decreased the Pb content by 13.62% compared to the Pb-exposed group. There was also a mild decrease in the renal endogenous concentration of magnesium (Mg) and elevation of the renal concentration of iron (Fe) in the salinomycin-treated group compared to controls. Overall, the results demonstrated that salinomycin is a more effective chelating agent for the treatment of Pb-induced alterations in renal morphology compared to deferiprone.

Cell-Free DNA Fragmentomics in Liquid Biopsy

Cell-free DNA (cfDNA) in bodily fluids has rapidly transformed the development of noninvasive prenatal testing, cancer liquid biopsy, and transplantation monitoring. Plasma cfDNA consists of a mixture of molecules originating from various bodily tissues. The study of the fragmentation patterns of cfDNA, also referred to as ‘fragmentomics’, is now an actively pursued area of biomarker research. Clues that cfDNA fragmentation patterns might carry information concerning the tissue of origin of cfDNA molecules have come from works demonstrating that circulating fetal, tumor-derived, and transplanted liver-derived cfDNA molecules have a shorter size distribution than the background mainly of hematopoietic origin. More recently, an improved understanding of cfDNA fragmentation has provided many emerging fragmentomic markers, including fragment sizes, preferred ends, end motifs, single-stranded jagged ends, and nucleosomal footprints. The intrinsic biological link between activities of various DNA nucleases and characteristic fragmentations has been demonstrated. In this review, we focus on the biological properties of cell-free DNA unveiled recently and their potential clinical applications.

Update on Toxic Neuropathies

Purpose of Review

Toxic neuropathies are an important preventable and treatable form of peripheral neuropathy. While many forms of toxic neuropathies have been recognized for decades, an updated review is provided to increase vigilant in this area of neurology. A literature review was conducted to gather recent information about toxic neuropathies, which included the causes, clinical findings, and treatment options in these conditions.

Recent Findings

Toxic neuropathies continue to cause significant morbidity throughout the world and the causative agents, particularly with regards to medications, do not appear to be diminishing. A wide variety of causes of toxic neuropathies exist, which include alcohol, industrial chemicals, biotoxins, and medications. Unfortunately, no breakthrough treatments have been developed and prevention and symptom management remain the standard of care.

Summary

A detailed medication, occupational and hobby exposure history is critical to identifying toxic neuropathies. Increased research is warranted to identify mechanisms of neurotoxic susceptibility and potential common pathomechanistic pathways for treatment across diverse toxic neuropathies.

Chelating Silicone Dendrons: Trying to Impact Organisms by Disrupting Ions at Interfaces

The viability of pathogens at interfaces can be disrupted by the presence of (cationic) charge and chelating groups. We report on the synthesis of silicone dendrimers and linear polymers based on a motif of hexadentate ligands with the ability to capture and deliver metal ions. Mono-, di- or trialkoxysilanes are converted in G1 to analogous vinylsilicones and then, iteratively using the Piers-Rubinsztajn reaction and hydrosilylation, each vinyl group is transformed into a trivinyl cluster at G2. The thiol-ene reaction with cysteamine or 3-mercaptopropionic acid and the trivinyl cluster leads to hexadentate ligands 3 × N–S or 3 × HOOC–S. The compounds were shown to effectively capture a variety of metals ions. Copper ion chelation was pursued in more detail, because of its toxicity. On average, metal ions form chelates with 2.4 of the three ligands in a cluster. Upon chelation, viscous oils are converted to (very) soft elastomers. Most of the ions could be stripped from the elastomers using aqueous EDTA solutions, demonstrating the ability of the silicones to both sequester and deliver ions. However, complete ion removal is not observed; at equilibrium, the silicones remain ionically crosslinked.

Thymoquinone Induces Nrf2 Mediated Adaptive Homeostasis: Implication for Mercuric Chloride-Induced Nephrotoxicity

BACKGROUND

the primary function of the kidney is to eliminate metabolic waste products and xenobiotics from the circulation. During this process, the kidney may become vulnerable to toxicity.

OBJECTIVE

it was aimed to investigate the impact of thymoquinone (TQ) in mercuric chloride (HgCl2)-induced nephrotoxicity through estimation of various proteins involved in natural defense mechanisms.

MATERIAL AND METHODS

HgCl2 (0.4 mg/kg) was administered to all groups (n = 5) except for the normal control. Three treatment groups received TQ (5, 10, and 15 mg/kg) 60 min before HgCl2 administration. The protective effect of TQ was evaluated from renal and liver function biomarkers, urine examination, glomerulus filtration rate (GFR), histopathological features, oxidative stress biomarkers, Hsp-70, apoptosis biomarkers, and gene expression.

RESULTS

TQ significantly attenuated hazardous effects of HgCl2 on renal and hepatic tissues. Urine albumin and glucose were considerably low in the treated groups in comparison with the HgCl2 group. TQ treatment also enhanced % GFR in rats. TQ-enhanced superoxide dismutase, catalase, and glutathione levels by enhancing the expression level of nuclear factor erythroid 2-related factor 2 (Nrf2). TQ increased Hsp-70 and Bcl-2 levels and reduced caspase-3 activity. TQ also protected cells against HgCl2-induced cell death and decreased % DNA fragmentation. TQ increased the expression of protective proteins metallothionein I and II and reduced the expression of kidney injury molecule-1 (Kim-1).

CONCLUSION

TQ showed protective effects against HgCl2-induced nephrotoxicity through modifications of various constitutive and inducible protein and enzyme levels in renal tissues.

Human exposure to toxic elements through facial cosmetic products: Dermal risk assessment

Facial cosmetics are the most commonly consumed product, mainly by the women from all over the world irrespective of their age. The facial cosmetics may be contaminated with several toxic elements, which can get absorb on to the facial skin and migrate to the blood vessels. Hence the absorbed toxic elements can cause further adverse effects on the human body. The present study aims to assess the toxic element contents (arsenic, lead, nickel, mercury, and cadmium) in commonly consumed facial cosmetics (face powder, foundation, lightening creams, moisturizer, eye shadow, lipsticks, eyeliner, blush, mascara, sunscreen) and to carry out the risk assessment through different methods. The dermal risk was evaluated as SED, NOAEL, MoS, HQ and ILCR, which is linked with the exposure of selected toxic elements. The total CDDE for all selected elements in facial cosmetic products was found in increasing order as follow: face powder > foundation > lightening creams > moisturizer > eye shadow > lipsticks > eyeliner > blush > mascara > sunscreen. The HQ and HI values for selected elements were found to be < 1 in all facial cosmetics. Whereas the probable MoS of selected toxic elements in all facial cosmetics except eyeliner were found to be 3-4 folds lower than the minimum value of 100 regulated by the WHO.

Recent Progress on Single-Molecule Detection Technologies for Food Safety

Rapid and sensitive detection technologies for food contaminants play vital roles in food safety. Due to the complexity of the food matrix and the trace amount distribution, traditional methods often suffer from unsatisfying accuracy, sensitivity, or specificity. In past decades, single-molecule detection (SMD) has emerged as a way to realize the rapid and ultrasensitive measurement with low sample consumption, showing a great potential in food contaminants detection. For instance, based on the nanopore technique, simple and effective methods for single-molecule analysis of food contaminants have been developed. To our knowledge, there has been a rare review that focuses on SMD techniques for food safety. The present review attempts to cover some typical SMD methods in food safety, including electrochemistry, optical spectrum, and atom force microscopy. Then, recent applications of these techniques for detecting food contaminants such as biotoxins, pesticides, heavy metals, and illegal additives are reviewed. Finally, existing research challenges and future trends of SMD in food safety are also tentatively proposed.

A Novel Diselenide-Probucol-Analogue Protects Against Methylmercury-Induced Toxicity in HT22 Cells by Upregulating Peroxide Detoxification Systems: a Comparison with Diphenyl Diselenide

Methylmercury (MeHg) is a ubiquitous environmental neurotoxicant whose mechanisms of action involve oxidation of endogenous nucleophilic groups (mainly thiols and selenols), depletion of antioxidant defenses, and disruption of neurotransmitter homeostasis. Diphenyl diselenide-(PhSe)₂-a model diaryl diselenide, has been reported to display significant protective effects against MeHg-induced neurotoxicity under both in vitro and in vivo experimental conditions. In this study, we compared the protective effects of (PhSe)₂ with those of RC513 (4,4'-diselanediylbis(2,6-di-tert-butylphenol), a novel diselenide-probucol-analog) against MeHg-induced toxicity in the neuronal (hippocampal) cell line HT22. Although both (PhSe)₂ and RC513 significantly mitigated MeHg- and tert-butylhydroperoxide (t-BuOOH)-cytotoxicity, the probucol analog exhibited superior protective effects, which were observed earlier and at lower concentrations compared to (PhSe)₂. RC513 treatment (at either 0.5 µM or 2 µM) significantly increased glutathione peroxidase (GPx) activity, which has been reported to counteract MeHg-toxicity. (PhSe)₂ was also able to increase GPx activity, but only at 2 µM. Although both compounds increased the Gpx1 transcripts at 6 h after treatments, only RC513 was able to increase mRNA levels of Prx2, Prx3, Prx5, and Txn2, which are also involved in peroxide detoxification. RC513 (at 2 µM) significantly increased GPx-1 protein expression in HT22 cells, although (PhSe)₂ displayed a minor (nonsignificant) effect in this parameter. In agreement, RC513 induced a faster and superior capability to cope with exogenously-added peroxide (t-BuOOH). In summary, when compared to the prototypical organic diaryl diselenide [(PhSe)₂], RC513 displayed superior protective properties against MeHg-toxicity in vitro; this was paralleled by a more pronounced upregulation of defenses related to detoxification of peroxides, which are well-known MeHg-derived intermediate oxidant species.

TanP: A Multifunctional Anionic Peptide From Tityus stigmurus Scorpion Venom

Anionic peptides of scorpions are molecules rich in aspartic and/or glutamic acid residues and correspond to a class of peptides without disulfide bonds that are still little explored. TanP is a linear anionic peptide (50 amino acid residues and net charge -20) present in the venom gland of the scorpion, Tityus stigmurus, with chelating properties for Cu2+ ion and immunomodulatory properties. The therapeutic application of chelating molecules is related to cases of acute or chronic intoxication by metals, neurodegenerative diseases, hematological diseases, healing of skin wounds, cardiovascular diseases, and cancer. In this approach, the chelating activity of TanP was evaluated in relation to new metal ions (Fe2+ and Zn2+) of biological importance, as well as its antioxidant, hemostatic, immunomodulatory, and healing potential, aiming to expand the biological and biotechnological potential of this peptide. TanP (25 µM) was able to form stable complexes with Fe2+ in a ratio of 1:5 (TanP: Fe2+). Theoretical results suggest that TanP can work as a sensor to identify and quantify Fe2+ ions. The fluorescence intensity of TanP (1.12 µM) decreased significantly after the addition of Fe2+, obtaining the highest ratio 1: 7.4 (TanP: Fe2+) that led to the lowest fluorescence intensity. For Zn2+, no relevant spectral change was noted. TanP (50 µM) showed a maximum of 3% of hemolytic activity, demonstrating biocompatibility, as well as exhibiting a 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity of above 70% at all the concentrations tested (1-25 μM), and 89.7% iron-chelating activity at 25 μM and 96% hydroxyl radical-scavenging activity at 73.6 μM. In addition, TanP (12.5 and 25 µM) revealed an anticoagulant effect, prolonging the clotting time in prothrombin time and activated partial thromboplastin time assays, with no fibrinogenolytic activity. TanP (12.5 and 25 µM) induced the release of TNF-α by murine macrophages, in the absence of lipopolysaccharides, with a concentration-dependent increase and also stimulated the migration of 3T3 cells in the in vitro healing assay. Thus, TanP revealed a multifunctional potential, being useful as a prototype for the development of new therapeutic and biotechnological agents.

Metal Ions, Metal Chelators and Metal Chelating Assay as Antioxidant Method

Heavy metals are essential for a wide range of biological processes, including the growth and reproduction of cells, synthesis of biomolecules, many enzymatic reactions, and the body’s immunity, but their excessive intake is harmful. Specifically, they cause oxidative stress (OS) and generate free radicals and reactive oxygen species (ROS) in metabolism. In addition, the accumulation of heavy metals in humans can cause serious damage to different organs, especially respiratory, nervous and reproductive and digestive systems. Biologically, metal chelation therapy is often used to treat metal toxicity. This process occurs through the interaction between the ligand and a central metal atom, forming a complex ring-like structure. After metals are chelated with appropriate chelating agents, their damage in metabolism can be prevented and efficiently removed from the body. On the other hand, heavy metals, including Zn, Fe and Cu, are necessary for the suitable functioning of different proteins including enzymes in metabolism. However, when the same metals accumulate at levels higher than the optimum level, they can easily become toxic and have harmful effects toward biomolecules. In this case, it induces the formation of ROS and nitrogen species (RNS) resulting in peroxidation of biological molecules such as lipids in the plasma membrane. Antioxidants have an increasing interest in many fields due to their protective effects, especially in food and pharmaceutical products. Screening of antioxidant properties of compounds needs appropriate methods including metal chelating assay. In this study, a general approach to the bonding and chelating properties of metals is described. For this purpose, the basic principles and chemical principles of metal chelation methods, both in vivo and in vitro, are outlined and discussed. Hence, in the main sections of this review, the descriptions related to metal ions, metal chelating, antioxidants, importance of metal chelating in biological system and definitions of metal chelating assays as widely used methods to determine antioxidant ability of compounds are provided. In addition, some chemical properties, technical and critical details of the used chelation methods are given.

Essential Metals in the Brain and the Application of Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry for their Detection

Metals are natural component of the ecosystem present throughout the layers of atmosphere; their abundant expression in the brain indicates their importance in the central nervous system (CNS). Within the brain tissue, their distribution is highly compartmentalized, the pattern of which is determined by their primary roles. Bio-imaging of the brain to reveal spatial distribution of metals within specific regions has provided a unique understanding of brain biochemistry and architecture, linking both the structures and the functions through several metal mediated activities. Bioavailability of essential trace metal is needed for normal brain function. However, disrupted metal homeostasis can influence several biochemical pathways in different fields of metabolism and cause characteristic neurological disorders with a typical disease process usually linked with aberrant metal accumulations. In this review we give a brief overview of roles of key essential metals (Iron, Copper and Zinc) including their molecular mechanisms and bio-distribution in the brain as well as their possible involvement in the pathogenesis of related neurodegenerative diseases. In addition, we also reviewed recent applications of Laser Ablation Inductively Couple Plasma Mass Spectrophotometry (LA-ICP-MS) in the detection of both toxic and essential metal dyshomeostasis in neuroscience research and other related brain diseases.

Synthetic Amphoteric Cryogels as an Antidote against Acute Heavy Metal Poisoning

The effectiveness of an amphoteric cryogel (AAC) as an oral sorbent (enerosorbent) for the treatment of acute poisoning of small animals (rats) with heavy metals (HMs) was studied in in vivo experiments. The morphological structure of the cryogel was examined using scanning electron microscopy/energy-dispersive X-ray analysis and confocal microscopy. The use of the cryogel in the treatment of rats administered an LD₅₀ dose of Cd(NO₃)₂, CsNO₃, Sr(NO₃)₂, or HgCl₂ in aqueous solution showed their high survival rate compared to the control group, which did not receive such treatment. The histological and chemical analysis of internal tissues and the biochemical analysis of the blood of the experimental animals showed the effectiveness of the cryogel in protecting the animals against the damaging effect of HMs on the organism comparable with unithiol, a chelating agent based on 2,3-dimercapto-1-propane sulfonic acid sodium salt (DMPS) approved for the treatment of acute poisoning with some heavy metals.

Potential of three local marine microalgae from Tunisian coasts for cadmium, lead and chromium removals

Metal elements are widely used in various industrial activities and are considered as common water source contaminants. Thus, the development of cost-effective, simple design and efficient processes for trace metal elements removal from contaminated water sources is of great interest. The effects of cadmium, lead and chromium on growth, biomolecules accumulation and metabolic responses of Amphora coffaeiformis, Navicula salinicola and Dunaliella salina isolated from Tunisian coasts were tested. The bioremediation capacities of the three microalgae strains and the mechanisms involved in ions metal removal were also investigated. N. salinicola and D. salina seem to be better tolerating to Cr, while A. coffaeiformis and N. salinicola showed high resistance to Pb. The expression profile analyses by qRT-PCR of the antioxidant defense-related genes revealed that Cd, Pb and Cr treatments induce the up-regulation of catalase and superoxide dismutase coding genes for A. coffaeiformis and D. salina. Regarding N. salinicola, the catalase coding gene seems to be overexpressed after Cd, Pb and Cr exposure while only Cd and Cr induce superoxide dismutase gene overexpression. Moreover, the phytochelatin synthase (a metal chelator synthesis-related gene) was up-regulated in N. salinicola, A. coffaeiformis and D. salina after Cr exposure and also in A. coffaeiformis and D. salina after Cd exposure. While Pb treatments induce overexpression of phytochelatin synthase coding gene only for D. salina. Studied strains showed promising metal removal efficiencies for both Pb and Cr ions metals reached 95% for D. salina. Ion metal removal mechanisms study revealed that intracellular bioaccumulation process is used by D. salina for Cr up-taking. However, both intracellular and extracellular removal mechanisms are involved for Pb and Cr removal using A. coffaeiformis, N. salinicola and for Pb removal using D. salina. FTIR analysis demonstrated that several functional groups as carboxyl, hydroxyl, amino, phosphate and sulfate may participate in the bioadsorption process.

Enterosorption in the Treatment of Heavy Metal Poisoning

Enterosorption is a cost-effective and efficient approach to reducing the impact of chronic exposure to heavy metals and radionuclides. As an auxiliary method to medical treatment, it can protect population chronically exposed to the intake of heavy metals or radioactivity due to industrial activities or in the aftermath of technogenic or natural accidents. This paper assesses the current state of the art in the treatment of acute and chronic heavy metal poisoning.

Ameliorative mechanisms of turmeric-extracted curcumin on arsenic (As)-induced biochemical alterations, oxidative damage, and impaired organ functions in rats

Arsenic (As) is known for its carcinogenic and hepatorenal toxic effects causing serious health problems in human beings. Turmeric (Curcuma longa L.) extracted curcumin (Cur) is a polyphenolic antioxidant which has ability to combat hazardous environmental toxicants. This study (28 days) was carried out to investigate the therapeutic efficacy of different doses of Cur (Cur: 80, 160, 240 mg kg^-1) against the oxidative damage in the liver and kidney of male rats caused by sodium arsenate (Na₃AsO₄) (10 mg L^-1). As exposure significantly elevated the values of organ index, markers of hepatic injury (i.e., alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP)) and renal functions (i.e., total bilirubin, urea and creatinine, total cholesterol, total triglycerides, and lipid peroxidation malondialdehyde (MDA)). Moreover, different antioxidant markers such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) activities in the liver and kidney tissues were reduced after As-induced toxicity. However, Na₃AsO₄ induced histopathological changes in various organs were minimized after the treatment with Cur. The alleviation effect of Cur was dosage dependent with an order of 240>160>80 mg kg^-1. The oral administration of Cur prominently alleviated the As-induced toxicity in liver and kidney tissues by reducing lipid peroxidation, ALT, AST, ALP, total bilirubin, urea, creatinine, total cholesterol, total triglycerides, and low-density lipoproteins (LDL). In addition, Cur being an antioxidant improved defense system by enhancing activities of SOD, CAT, GPx, and GR. Overall, the findings explain the capability of Cur to counteract the oxidative alterations as well as hepatorenal injuries due to As intoxication.

Cadmium-Induced Kidney Injury in Mice Is Counteracted by a Flavonoid-Rich Extract of Bergamot Juice, Alone or in Association with Curcumin and Resveratrol, via the Enhancement of Different Defense Mechanisms

Cadmium (Cd) represents a public health risk due to its non-biodegradability and long biological half-life. The main target of Cd is considered the kidney, where it accumulates. No effective treatment for Cd poisoning is available so that several therapeutic approaches were proposed to prevent damages after Cd exposure. We evaluated the effects of a flavonoid-rich extract of bergamot juice (BJe), alone or in association with curcumin (Cur) and resveratrol (Re), in the kidney of mice exposed to cadmium chloride (CdCl₂). Male mice were administered with CdCl₂ and treated with Cur, Re, or BJe alone or in combination for 14 days. The kidneys were processed for biochemical, structural and morphometric evaluation. Cd treatment significantly increased urea nitrogen and creatinine levels, along with tp53, Bax, Nos2 and Il1b mRNA, while reduced that of Bcl2, as well as glutathione (GSH) content and glutathione peroxidase (GPx) activity. Moreover, Cd caused damages to glomeruli and tubules, and increased Nrf2, Nqo1 and Hmox1 gene expression. Cur, Re and BJe at 40 mg/kg significantly improved all parameters, while BJe at 20 mg/kg showed a lower protective effect. After treatment with the associations of the three nutraceuticals, all parameters were close to normal, thus suggesting a new potential strategy in the protection of renal functions in subjects exposed to environmental toxicants.

Chelation therapy in liver diseases of childhood: Current status and response

Chelation is the mainstay of therapy in certain pediatric liver diseases. Copper and iron related disorders require chelation. Wilson’s disease (WD), one of the common causes of cirrhosis in children is treated primarily with copper chelating agents like D-penicillamine and trientine. D-Penicillamine though widely used due its high efficacy in hepatic WD is fraught with frequent adverse effects resulting discontinuation. Trientine, an alternative drug has comparable efficacy in hepatic WD but has lower frequency of adverse effects. The role of ammonium tetra-thiomolybdate is presently experimental in hepatic WD. Indian childhood cirrhosis is related to excessive copper ingestion, rarely seen in present era. D-Penicillamine is effective in the early part of this disease with reversal of clinical status. Iron chelators are commonly used in secondary hemochromatosis of liver in hemolytic anemias. There are strict chelation protocols during bone marrow transplant. The role of iron chelation in neonatal hemochromatosis is presently not in vogue due to its poor efficacy and availability of other modalities of therapy. Hereditary hemochromatosis is rare in children and the use of iron chelators in this condition is limited.

X-ray photoemission studies of the interaction of metals and metal ions with DNA

X-ray Photoelectron Spectroscopy (XPS) has been used to study the interactions of heavy metal ions with DNA with some success. Surface sensitivity and selectivity of XPS are advantageous for identifying and characterizing the chemical and elemental structure of the DNA to metal interaction. This review summarizes the status of what amounts to a large part of the photoemission investigations of biomolecule interactions with metals and offers insight into the mechanism for heavy metal-bio interface interactions. Specifically, it is seen that metal interaction with DNA results in conformational changes in the DNA structure.

Santiago Jiménez, David A. Egas, Kelly Swing. Is release of rehabilitated wildlife with embedded lead ammunition advisable? Plumbism in a Jaguar Panthera Onca (Mammalia: Carnivora: Felidae), survivor of gunshot wounds

Lead poisoning is a threat to wildlife, particularly after ingestion of lead ammunition derived from hunting activities. Little information, however, is available concerning plumbism in wild animals that survive the trauma associated with gunshot wounds. This study presents a possible example of lead intoxication by embedded pellets in a Jaguar Panthera onca nineteen months after being injured by a shotgun blast. In addition, the possible path of incorporation of lead into the trophic chain after the eventual release and death of an impacted animal, thereby expanding and prolonging the toxic effects of lead ammunition, is discussed. Direct intoxication by ammunition retained in the body of wild animals, as well as the indirect impacts on predators and scavengers that consume their flesh, should be sufficient reasons to reconsider the release of individuals with embedded lead ammunition into the wild.

Cleaner technologies to combat heavy metal toxicity

Heavy metals frequently occur as silent poisons present in our daily diet, the environment we live and the products we use, leaving us victims to various associated drastic health and ecological bad effects even in meagre quantities. The prevalence of heavy metals can be traced from children's toys, electronic goods, industrial effluents, pesticide preparation, and even in drinking water in some instances; necessitating methods to remediate them. The current review discusses the various physicochemical and biological methods employed to tackle the problem of heavy metal pollution. Apart from the conventional methods following the principles of adsorption, precipitation, coagulation, and various separation techniques, the advancements made in the directions of biological heavy metal detoxification using microbes, plants, algae have been critically analyzed to identify the specific utility of different agents for specific heavy metal removal. The review paper is a nutshell of different heavy metal remediation strategies, their merits, demerits, and modifications done to alleviate process of heavy metal pollution.

Advances in the Therapeutic Application of Small-Molecule Inhibitors and Repurposed Drugs against Snakebite

The World Health Organization has declared snakebite as a neglected tropical disease. Antivenom administration is the sole therapy against venomous snakebite; however, several limitations of this therapy reinforce the dire need for an alternative and/or additional treatment against envenomation. Inhibitors against snake venoms have been explored from natural resources and are synthesized in the laboratory; however, repurposing of small-molecule therapeutics (SMTs) against the principal toxins of snake venoms to inhibit their lethality and/or obnoxious effect of envenomation has been garnering greater attention owing to their established pharmacokinetic properties, low-risk attributes, cost-effectiveness, ease of administration, and storage stability. Nevertheless, SMTs are yet to be approved and commercialized for snakebite treatment. Therefore, we have systematically reviewed and critically analyzed the scenario of small synthetic inhibitors and repurposed drugs against snake envenomation from 2005 to date and proposed novel approaches and commercialization strategies for the development of efficacious therapies against snake envenomation.

Harnessing selectivity in chemical sensing via supramolecular interactions: from functionalization of nanomaterials to device applications

Chemical sensing is a strategic field of science and technology ultimately aiming at improving the quality of our lives and the sustainability of our Planet. Sensors bear a direct societal impact on well-being, which includes the quality and composition of the air we breathe, the water we drink, and the food we eat. Pristine low-dimensional materials are widely exploited as highly sensitive elements in chemical sensors, although they suffer from lack of intrinsic selectivity towards specific analytes. Here, we showcase the most recent strategies on the use of (supra)molecular interactions to harness the selectivity of suitably functionalized 0D, 1D, and 2D low-dimensional materials for chemical sensing. We discuss how the design and selection of receptors via machine learning and artificial intelligence hold a disruptive potential in chemical sensing, where selectivity is achieved by the design and high-throughput screening of large libraries of molecules exhibiting a set of affinity parameters that dictates the analyte specificity. We also discuss the importance of achieving selectivity along with other relevant characteristics in chemical sensing, such as high sensitivity, response speed, and reversibility, as milestones for true practical applications. Finally, for each distinct class of low-dimensional material, we present the most suitable functionalization strategies for their incorporation into efficient transducers for chemical sensing.

Ayurveda intervention for brass-induced heavy metal toxicity: A report from the single-arm pilot study

BACKGROUND

Brass is a copper-zinc alloy that also contains additional elements, including lead. Industrial operations on brass produce dust and fumes that can be harmful to an individual's health. Ayurveda recommends Dadima Svarasa and Triphala Churna for the management of symptoms caused due to brass toxicity.

OBJECTIVE

To obtain preliminary evidence on the efficacy of Triphala Churna (powder mixture of three myrobalans) and Dadima Svarasa (pomegranate juice) in the management of brass-associated high serum level of copper, zinc, lead, and their harms through an open-label single-arm pilot study.

MATERIALS AND METHODS

A total of 20 workers with brass toxicity and increased level of one or more of the serum ions including copper, zinc and lead were prescribed. 5gm Triphala powder once daily and Dadima Svarasa 40 ml in two divided doses were administered daily for 28 days. Changes in serum concentration of heavy metals and common health problems like anorexia, headache, dizziness, weakness, nausea, nose irritation, eye irritation, epigastric pain, abdominal distention, chest pain, dyspnea, cough, lumbar pain, body ache, numbness, and occupational dermatitis were reported at baseline and end of the trial.

RESULTS

Trial drugs were found to produce significant decrease in mean values of serum copper (p < 0.001) and serum lead (p < 0.001) whereas significant increase in mean values of serum zinc (p > 0.001) was observed. Significant relief was observed in nausea (p = 0.005), anorexia (p = 0.000), epigastric pain (p = 0.001), abdominal distention (p = 0.014), weakness (p = 0.005) and body ache (p = 0.005).

CONCLUSION

Triphala Churna along with Dadima Svarasa are safe and effective in the management of brass-associated high serum levels of copper and lead and their health hazards.

Antimicrobial and antibiofilm activities of Cu(II) Schiff base complexes against methicillin-susceptible and resistant Staphylococcus aureus

Background

Methicillin-resistance S. aureus (MRSA) possesses the ability to resist multiple antibiotics and form biofilm. Currently, vancomycin remains the last drug of choice for treatment of MRSA infection. The emergence of vancomycin-resistant S. aureus (VRSA) has necessitated the development of new therapeutic agents against MRSA. In this study, the antimicrobial and antibiofilm activities of two copper-complexes derived from Schiff base (SBDs) were tested individually, and in combination with oxacillin (OXA) and vancomycin (VAN) against reference strains methicillin-susceptible and methicillin-resistant Staphylococcus aureus. The toxicity of the SBDs was also evaluated on a non-cancerous mammalian cell line.

Methods

The antimicrobial activity was tested against the planktonic S. aureus cells using the microdilution broth assay, while the antibiofilm activity were evaluated using the crystal violet and resazurin assays. The cytotoxicity of the SBDs was assessed on MRC5 (normal lung tissue), using the MTT assay.

Results

The individual SBDs showed significant reduction of biomass and metabolic activity in both S. aureus strains. Combinations of the SBDs with OXA and VAN were mainly additive against the planktonic cells and cells in the biofilm. Both the compounds showed moderate toxicity against the MRC5 cell line. The selectivity index suggested that the compounds were more cytotoxic to S. aureus than the normal cells.

Conclusion

Both the SBD compounds demonstrated promising antimicrobial and antibiofilm activities and have the potential to be further developed as an antimicrobial agent against infections caused by MRSA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12941-021-00473-4.

Living with the enemy: from protein-misfolding pathologies we know, to those we want to know

Conformational diseases are caused by the aggregation of misfolded proteins. The risk for such pathologies develops years before clinical symptoms appear, and is higher in people with alpha-1 antitrypsin (AAT) polymorphisms. Thousands of people with alpha-1 antitrypsin deficiency (AATD) are underdiagnosed. Enemy-aggregating proteins may reside in these underdiagnosed AATD patients for many years before a pathology for AATD fully develops. In this perspective review, we hypothesize that the AAT protein could exert a new and previously unconsidered biological effect as an endogenous metal ion chelator that plays a significant role in essential metal ion homeostasis. In this respect, AAT polymorphism may cause an imbalance of metal ions, which could be correlated with the aggregation of amylin, tau, amyloid beta, and alpha synuclein proteins in type 2 diabetes mellitus (T2DM), Alzheimer's and Parkinson's diseases, respectively.

Synthesis and crystal structure of a heterobimetallic cadmium-sodium complex of 1,3,5-triazine-2,4,6-trione, [CdNa2(C3H2N3O3)4(H2O)8]

Heterobimetallic crystals of a cadmium-sodium complex of 1,3,5-triazine-2,4,6-trione, namely, μ-aqua-1:2κ2 O:O-hepta-aqua-1κ3 O,2κ2 O,3κ2 O-bis-(μ-4,6-dioxo-1,4,5,6-tetra-hydro-1,3,5-triazin-2-olato)-1:2κ2 O 2:N 1;2:3κ2 N 1:O 2-bis-(4,6-dioxo-1,4,5,6-tetra-hydro-1,3,5-triazin-2-olato)-1κO 2,3κO 2-2-cadmium-1,3-disodium, [CdNa2(C3H2N3O3)4(H2O)8], were grown by the single gel diffusion technique. The asymmetric unit of the title compound comprises four 1,3,5-triazine-2,4,6-trione ligands, two sodium atoms and one cadmium atom. Of the four ligands, two are monodentately coordinated to two Na atoms. The third ligand is coordinated bidentately to one Na and the Cd atom and the fourth is also coordinated bidentately to the Cd atom and the other Na atom. All the metal atoms are six-coordinate with a distorted octa-hedral geometry. The water mol-ecules bridge the Na atoms, constructing coordination polymer chains along the a axis and hence are linked by two Cd and one Na coordinations through the cyanuric acid ligands present in the coordination polymer chains, generating a two-dimensional coordination polymer in the (110) plane. The polymer formation is further assisted by means of many inter-molecular and intra-molecular N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonds between the water mol-ecules and the ligands.

Metallobiology and therapeutic chelation of biometals (copper, zinc and iron) in Alzheimer's disease: Limitations, and current and future perspectives

BACKGROUND

Alzheimer's disease (AD) is the most prevalent cause of cognitive impairment and dementia worldwide. The pathobiology of the disease has been studied in the form of several hypotheses, ranging from oxidative stress, amyloid-beta (Aβ) aggregation, accumulation of tau forming neurofibrillary tangles (NFT) through metal dysregulation and homeostasis, dysfunction of the cholinergic system, and to inflammatory and autophagic mechanism. However, none of these hypotheses has led to confirmed diagnostics or approved cure for the disease.

OBJECTIVE

This review is aimed as a basic and an encyclopedic short course into metals in AD and discusses the advances in chelation strategies and developments adopted in the treatment of the disease. Since there is accumulating evidence of the role of both biometal dyshomeostasis (iron (Fe), copper (Cu), and zinc (Zn)) and metal-amyloid interactions that lead to the pathogenesis of AD, this review focuses on unraveling therapeutic chelation strategies that have been considered in the treatment of the disease, aiming to sequester free and protein-bound metal ions and reducing cerebral metal burden. Promising compounds possessing chemically modified moieties evolving as multi-target ligands used as anti-AD drug candidates are also covered.

RESULTS AND CONCLUSION

Several multidirectional and multifaceted studies on metal chelation therapeutics show the need for improved synthesis, screening, and analysis of compounds to be able to effectively present chelating anti-AD drugs. Most drug candidates studied have limitations in their physicochemical properties; some enhance redistribution of metal ions, while others indirectly activate signaling pathways in AD. The metal chelation process in vivo still needs to be established and the design of potential anti-AD compounds that bi-functionally sequester metal ions as well as inhibit the Aβ aggregation by competing with the metal ions and reducing metal-induced oxidative damage and neurotoxicity may signal a bright end in chelation-based therapeutics of AD.

Study on the Efficacy and Mechanism of Lycium barbarum Polysaccharide against Lead-Induced Renal Injury in Mice

Lead is one of the most common heavy metal pollutants in the environment. Prolonged exposure to lead will induce oxidative stress, inflammation, and apoptosis in the kidneys, which in turn causes kidney injury. Lycium barbarum polysaccharide (LBP) is well known for its numerous pharmacological properties. This study aims to explore the efficacy and mechanism of LBP against lead-induced kidney damage in mice. Symptoms of renal injury were induced in mice by using 25 mg/kg lead acetate (PbAc₂), and different doses of LBP (200, 400, and 600 mg/kg BW) were orally administrated to PbAc₂-treated mice for five weeks. The results of the pharmacodynamics experiment showed that the renal pathological damages, serum creatinine (Cre), blood urea nitrogen (BUN), and kidney index of PbAc₂-treated mice could be significantly alleviated by treatment with LBP. Further, LBP treatment significantly increased the weight and feed intake of PbAc₂-treated mice. The dose effect results indicated that a medium dose of LBP was superior to high and low doses. The results of mechanistic experiments showed that LBP could attenuate oxidative stress, inflammation, and apoptosis in the kidneys of mice with lead toxicity by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway.