Zinc stimulates the production of toxic reactive oxygen species (ROS) and inhibits glutathione reductase in astrocytes

Verifying the cytotoxicity of a biodegradable zinc alloy with nanodiamond sensors

Metals are widely utilized as implant materials for bone fixtures as well as stents. Biodegradable versions of these implants are highly desirable since patients do not have to undergo a second surgery for the materials to be removed. Attractive options for such materials are zinc silver alloys since they also offer the benefit of being antibacterial. However, it is important to investigate the effect of the degradation products of such alloys on the surrounding cells, taking into account silver cytotoxicity. Here we investigated zinc alloyed with 1 % of silver (Zn1Ag) and how differently concentrated extracts (1 %-100 %) of this material impact human umbilical vein endothelial cells (HUVECs). More specifically, we focused on free radical generation and oxidative stress as well as the impact on cell viability. To determine free radical production we used diamond-based quantum sensing as well as conventional fluorescent assays. The viability was assessed by observing cell morphology and the metabolic activity via the MTT assay. We found that 1 % and 10 % extracts are well tolerated by the cells. However, at higher extract concentrations we observed severe impact on cell viability and oxidative stress. We were also able to show that quantum sensing was able to detect significant free radical generation even at the lowest tested concentrations.

Interactions of binary mixtures of metals on rainbow trout (Oncorhynchus mykiss) heart mitochondrial H2O2 homeodynamics

For continuous pumping of blood, the heart needs a constant supply of energy (ATP) that is primarily met via oxidative phosphorylation in the mitochondria of cardiomyocytes. However, sustained high rates of electron transport for energy conversion redox reactions predisposes the heart to the production of reactive oxygen species (ROS) and oxidative stress. Mitochondrial ROS are fundamental drivers of responses to environmental stressors including metals but knowledge of how combinations of metals alter mitochondrial ROS homeodynamics remains sparse. We explored the effects and interactions of binary mixtures of copper (Cu), cadmium (Cd), and zinc (Zn), metals that are common contaminants of aquatic systems, on ROS (hydrogen peroxide, H2O2) homeodynamics in rainbow trout (Oncorhynchus mykiss) heart mitochondria. Isolated mitochondria were energized with glutamate-malate or succinate and exposed to a range of concentrations of the metals singly and in equimolar binary concentrations. Speciation analysis revealed that Cu was highly complexed by glutamate or Tris resulting in Cu2+ concentrations in the picomolar to nanomolar range. The concentration of Cd2+ was 7.2-7.5 % of the total while Zn2+ was 15 % and 21 % of the total during glutamate-malate and succinate oxidation, respectively. The concentration-effect relationships for Cu and Cd on mitochondrial H2O2 emission depended on the substrate while those for Zn were similar during glutamate-malate and succinate oxidation. Cu + Zn and Cu + Cd mixtures exhibited antagonistic interactions wherein Cu reduced the effects of both Cd and Zn, suggesting that Cu can mitigate oxidative distress caused by Cd or Zn. Binary combinations of the metals acted additively to reduce the rate constant and increase the half-life of H2O2 consumption while concomitantly suppressing thioredoxin reductase and stimulating glutathione peroxidase activities. Collectively, our study indicates that binary mixtures of Cu, Zn, and Cd act additively or antagonistically to modulate H2O2 homeodynamics in heart mitochondria.

Zinc-Modified Titanate Nanotubes as Radiosensitizers for Glioblastoma: Enhancing Radiotherapy Efficacy and Monte Carlo Simulations

Radiotherapy (RT) is the established noninvasive treatment for glioblastoma (GBM), a highly aggressive malignancy. However, its effectiveness in improving patient survival remains limited due to the radioresistant nature of GBM. Metal-based nanostructures have emerged as promising strategies to enhance RT efficacy. Among them, titanate nanotubes (TNTs) have gained significant attention due to their biocompatibility and cost-effectiveness. This study aimed to synthesize zinc-modified TNTs (ZnTNT) from sodium TNTs (NaTNT), in addition to characterizing the formed nanostructures and evaluating their radiosensitization effects in GBM cells (U87 and U251). Hydrothermal synthesis was employed to fabricate the TNTs, which were characterized using various techniques, including transmission electron microscopy (TEM), energy-dispersive spectroscopy, scanning-transmission mode, Fourier-transform infrared spectroscopy, ICP-MS (inductively coupled plasma mass spectrometry), X-ray photoelectron spectroscopy, and zeta potential analysis. Cytotoxicity was evaluated in healthy (Vero) and GBM (U87 and U251) cells by the MTT assay, while the internalization of TNTs was observed through TEM imaging and ICP-MS. The radiosensitivity of ZnTNT and NaTNT combined with 5 Gy was evaluated using clonogenic assays. Monte Carlo simulations using the MCNP6.2 code were performed to determine the deposited dose in the culture medium for RT scenarios involving TNT clusters and cells. The results demonstrated differences in the dose deposition values between the scenarios with and without TNTs. The study revealed that ZnTNT interfered with clonogenic integrity, suggesting its potential as a powerful tool for GBM treatment.

Combination of Hydrolysable Tannins and Zinc Oxide on Enterocyte Functionality: In Vitro Insights

The management of gastrointestinal disease in animals represents a significant challenge in veterinary and zootechnic practice. Traditionally, acute symptoms have been treated with antibiotics and high doses of zinc oxide (ZnO). However, concerns have been raised regarding the potential for microbial resistance and ecological detriment due to the excessive application of this compound. These concerns highlight the urgency of minimizing the use of ZnO and exploring sustainable nutritional solutions. Hydrolysable tannins (HTs), which are known for their role in traditional medicine for acute gastrointestinal issues, have emerged as a promising alternative. This study examined the combined effect of food-grade HTs and subtherapeutic ZnO concentration on relevant biological functions of Caco-2 cells, a widely used model of the intestinal epithelial barrier. We found that, when used together, ZnO and HTs (ZnO/HTs) enhanced tissue repair and improved epithelial barrier function, normalizing the expression and functional organization of tight junction proteins. Finally, the ZnO/HTs combination strengthened enterocytes' defense against oxidative stress induced by inflammation stimuli. In conclusion, combining ZnO and HTs may offer a suitable and practical approach for decreasing ZnO levels in veterinary nutritional applications.

Adult aberrant astrocytes submitted to late passage cultivation lost differentiation markers and decreased their pro-inflammatory profile

In amyotrophic lateral sclerosis (ALS), astrocytes are considered key players in some non-cell non-neuronal autonomous mechanisms that underlie motor neuron death. However, it is unknown how much of these deleterious features were permanently acquired. To assess this point, we evaluated if the most remarkable features of neurotoxic aberrant glial phenotypes (AbAs) isolated from paralytic rats of the ALS model G93A Cu/Zn superoxide dismutase 1 (SOD1) could remain upon long lasting cultivation. Real time PCR, immunolabelling and zymography analysis showed that upon many passages, AbAs preserved the cell proliferation capacity, mitochondrial function and response to different compounds that inhibit some key astrocyte functions but decreased the expression of parameters associated to cell lineage, homeostasis and inflammation. As these results are contrary to the sustained inflammatory status observed along disease progression in SOD1G93A rats, we propose that the most AbAs remarkable features related to homeostasis and neurotoxicity were not permanently acquired and might depend on the signaling coming from the injuring microenvironment present in the degenerating spinal cord of terminal rats.

Prophylactic zinc and therapeutic selenium administration in adult rats prevents long-term cognitive and behavioral sequelae by a transient ischemic attack

The transient hypoxic-ischemic attack, also known as a minor stroke, can result in long-term neurological issues such as memory loss, depression, and anxiety due to an increase in nitrosative stress. The individual or combined administration of chronic prophylactic zinc and therapeutic selenium is known to reduce nitrosative stress in the first seven days post-reperfusion and, due to an antioxidant effect, prevent cell death. Besides, zinc or selenium, individually administered, also causes antidepressant and anxiolytic effects. Therefore, this work evaluated whether combining zinc and selenium could prevent stroke-elicited cognition and behavior deficits after 30 days post-reperfusion. Accordingly, we assessed the expression of growth factors at 7 days post-reperfusion, a four-time course of memory (from 7 to 28 days post-learning test), and cell proliferation, depression, and anxiety-like behavior at 30 days post-reperfusion. Male Wistar rats with a weight between 190 and 240 g) were treated with chronic prophylactic zinc administration with a concentration of 0.2 mg/kg for 15 days before common carotid artery occlusion (10 min) and then with therapeutic selenium (6 μg/kg) for 7 days post-reperfusion. Compared with individual administrations, the administration combined of prophylactic zinc and therapeutic selenium decreased astrogliosis, increased growth factor expression, and improved cell proliferation and survival in two regions, the hippocampus, and cerebral cortex. These effects prevented memory loss, depression, and anxiety-like behaviors. In conclusion, these results demonstrate that the prophylactic zinc administration combined with therapeutic selenium can reduce the long-term sequelae caused by the transient ischemic attack. Significance statement. A minor stroke caused by a transient ischemic attack can result in psychomotor sequelae that affect not only the living conditions of patients and their families but also the economy. The incidence of these micro-events among young people has increased in the world. Nonetheless, there is no deep understanding of how this population group responds to regular treatments (Ekker and et al., 2018) [1]. On the basis that zinc and selenium have antioxidant, anti-inflammatory, and regenerative properties in stroke animal models, our work explored whether the chronic combined administration of prophylactic zinc and therapeutic selenium could prevent neurological sequelae in the long term in a stroke rat model of unilateral common carotid artery occlusion (CCAO) by 10-min. Our results showed that this combined treatment provided a long-term neuroprotective effect by decreasing astrogliosis, memory loss, anxiety, and depression-like behavior.

Effects of L-Type Voltage-Gated Calcium Channel (LTCC) Inhibition on Hippocampal Neuronal Death after Pilocarpine-Induced Seizure

Epilepsy, marked by abnormal and excessive brain neuronal activity, is linked to the activation of L-type voltage-gated calcium channels (LTCCs) in neuronal membranes. LTCCs facilitate the entry of calcium (Ca2+) and other metal ions, such as zinc (Zn2+) and magnesium (Mg2+), into the cytosol. This Ca2+ influx at the presynaptic terminal triggers the release of Zn2+ and glutamate to the postsynaptic terminal. Zn2+ is then transported to the postsynaptic neuron via LTCCs. The resulting Zn2+ accumulation in neurons significantly increases the expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits, contributing to reactive oxygen species (ROS) generation and neuronal death. Amlodipine (AML), typically used for hypertension and coronary artery disease, works by inhibiting LTCCs. We explored whether AML could mitigate Zn2+ translocation and accumulation in neurons, potentially offering protection against seizure-induced hippocampal neuronal death. We tested this by establishing a rat epilepsy model with pilocarpine and administering AML (10 mg/kg, orally, daily for 7 days) post-epilepsy onset. We assessed cognitive function through behavioral tests and conducted histological analyses for Zn2+ accumulation, oxidative stress, and neuronal death. Our findings show that AML's LTCC inhibition decreased excessive Zn2+ accumulation, reactive oxygen species (ROS) production, and hippocampal neuronal death following seizures. These results suggest amlodipine's potential as a therapeutic agent in seizure management and mitigating seizures' detrimental effects.

Contribution of zinc accumulation to ischemic brain injury and its mechanisms about oxidative stress, inflammation, and autophagy: an update

Ischemic stroke is a leading cause of death and disability worldwide, and presently, there is no effective neuroprotective therapy. Zinc is an essential trace element that plays important physiological roles in the central nervous system. Free zinc concentration is tightly regulated by zinc-related proteins in the brain under normal conditions. Disruption of zinc homeostasis, however, has been found to play an important role in the mechanism of brain injury following ischemic stroke. A large of free zinc releases from storage sites after cerebral ischemia, which affects the functions and survival of nerve cells, including neurons, astrocytes, and microglia, resulting in cell death. Ischemia-triggered intracellular zinc accumulation also disrupts the function of blood-brain barrier via increasing its permeability, impairing endothelial cell function, and altering tight junction levels. Oxidative stress and neuroinflammation have been reported to be as major pathological mechanisms in cerebral ischemia/reperfusion injury. Studies have showed that the accumulation of intracellular free zinc could impair mitochondrial function to result in oxidative stress, and form a positive feedback loop between zinc accumulation and reactive oxygen species production, which leads to a series of harmful reactions. Meanwhile, elevated intracellular zinc leads to neuroinflammation. Recent studies also showed that autophagy is one of the important mechanisms of zinc toxicity after ischemic injury. Interrupting the accumulation of zinc will reduce cerebral ischemia injury and improve neurological outcomes. This review summarizes the role of zinc toxicity in cellular and tissue damage following cerebral ischemia, focusing on the mechanisms about oxidative stress, inflammation, and autophagy.

Are Zn(II) pincer complexes efficient apoptosis inducers? a deep insight into their activity against A549 lung cancer cells

To expand the array of chemotherapeutic drugs, earth-abundant metal complexes are found to be the future direction. In this regard, new zinc(II) complexes 1-3 of 8-aminoquinoline-based pincer ligands were synthesized, characterized and tested for their anticancer activity. The IC50 values of these complexes were estimated by an MTT assay to be 16.35-17.95 μM and 33.35-40 μM against A549 lung and MCF-7 breast cancer cells respectively. Among them, 3 was slightly better than the other complexes and, thus, subjected to detailed studies. Moreover, the ligand corresponding to 3 was less active against both the cell lines than the complex. Further, 3 showed no toxicity against normal fibroblast cell line L929, which instantly elevated the drug characteristic of our complex. An AO-EB staining assay revealed that 3 can induce apoptosis in A549, and it was quantified by flow cytometry as 22.77%. Moreover, the depolarization of the mitochondrial membrane potential determined by JC-1 staining indicated excess ROS production sites in the mitochondria, which was confirmed by carboxy-H2DCFDA staining. Interestingly, the present complexes show better activity than that of the standard drug cisplatin against A549 cells. Overall, the studies provided promising results that can be extended for clinical applications.

Neuroprotective potential of trimetazidine against tramadol-induced neurotoxicity: role of PI3K/Akt/mTOR signaling pathways

Tramadol (TRA) causes neurotoxicity whereas trimetazidine (TMZ) is neuroprotective. The potential involvement of the PI3K/Akt/mTOR signaling pathway in the neuroprotection of TMZ against TRA-induced neurotoxicity was evaluated. Seventy male Wistar rats were divided into groups. Groups 1 and 2 received saline or TRA (50 mg/kg). Groups 3, 4, and 5 received TRA (50 mg/kg) and TMZ (40, 80, or 160 mg/kg) for 14 days. Group 6 received TMZ (160 mg/kg). Hippocampal neurodegenerative, mitochondrial quadruple complex enzymes, phosphatidylinositol-3-kinases (PI3Ks)/protein kinase B levels, oxidative stress, inflammatory, apoptosis, autophagy, and histopathology were evaluated. TMZ decreased anxiety and depressive-like behavior induced by TRA. TMZ in tramadol-treated animals inhibited lipid peroxidation, GSSG, TNF-α, and IL-1β while increasing GSH, SOD, GPx, GR, and mitochondrial quadruple complex enzymes in the hippocampus. TRA inhibited Glial fibrillary acidic protein expression and increased pyruvate dehydrogenase levels. TMZ reduced these changes. TRA decreased the level of JNK and increased Beclin-1 and Bax. TMZ decreased phosphorylated Bcl-2 while increasing the unphosphorylated form in tramadol-treated rats. TMZ activated phosphorylated PI3Ks, Akt, and mTOR proteins. TMZ inhibited tramadol-induced neurotoxicity by modulating the PI3K/Akt/mTOR signaling pathways and its downstream inflammatory, apoptosis, and autophagy-related cascades.

Exposure to Zinc Oxide Nanoparticles Increases Estradiol Levels and Induces an Antioxidant Response in Antral Ovarian Follicles In Vitro

The use of zinc oxide nanoparticles (ZnO NP) in consumer products is increasing, raising concern about their potential toxicity to human health. Nanoparticles have endocrine disrupting effects and can induce oxidative stress, leading to biomolecule oxidation and cell dysfunction. The ovary is one of the most important endocrine organs in female reproduction. Nanoparticles accumulate in the ovary, but it is unknown whether and how exposure to these materials disrupts antral follicle functions. Thus, this study tested the hypothesis that the in vitro exposure to ZnO NPs affects the steroidogenic pathway and induces oxidative stress in ovarian antral follicles. Antral follicles from CD-1 mice were cultured with ZnO NPs (5, 10, and 15 µg/mL) for 96 h. ZnO NP exposure did not affect apoptosis and cell cycle regulators at any of the tested concentrations. ZnO NP exposure at low levels (5 µg/mL) increased aromatase levels, leading to increased estradiol levels and decreased estrogen receptor alpha (Esr1) expression. ZnO NP exposure at 15 µg/mL induced an antioxidant response in the antral follicles as evidenced by changes in expression of antioxidant molecules (Nrf2, Cat, Sod1, Gsr, Gpx) and decreased levels of reactive oxygen species. Interestingly, ZnO NPs dissolve up to 50% in media and are internalized in cells as soon as 1 h after culture. In conclusion, ZnO NPs are internalized in antral follicles, leading to increased estrogen production and an antioxidant response.

Mancozeb-induced cytotoxicity in human erythrocytes: enhanced generation of reactive species, hemoglobin oxidation, diminished antioxidant power, membrane damage and morphological changes

Mancozeb is an ethylene bis-dithiocarbamate fungicide extensively used in agriculture to safeguard crops from various fungal diseases. The general population is exposed to mancozeb through consumption of contaminated food or water. Here, we have investigated the effect of mancozeb on isolated human erythrocytes under in vitro conditions. Erythrocytes were treated with different concentrations of mancozeb (0, 5, 10, 25, 50, 100 μM) and incubated for 24 h at 37 °C. Analysis of biochemical parameters and cell morphology showed dose-dependent toxicity of mancozeb in human erythrocytes. Mancozeb treatment caused hemoglobin oxidation and heme degradation. Protein and lipid oxidation were enhanced, while a significant decrease was seen in reduced glutathione and total sulfhydryl content. A significant increase in the generation of reactive oxygen and nitrogen species was detected in mancozeb-treated erythrocytes. The antioxidant capacity and the activity of key antioxidant enzymes were greatly diminished, while crucial metabolic pathways were inhibited in erythrocytes. Damage to the erythrocyte membrane on mancozeb treatment was apparent from increased cell lysis and osmotic fragility, along with the impairment of the plasma membrane redox system. Mancozeb also caused morphological alterations and transformed the normal discoid-shaped erythrocytes into echinocytes and stomatocytes. Thus, mancozeb induces oxidative stress in human erythrocytes, impairs the antioxidant defense system, oxidizes cellular components, that will adversely affect erythrocyte structure and function.

Water Hardness Improves the Antioxidant Response of Zinc-Exposed Goldfish (Carassius auratus)

Zinc (Zn), a heavy metal, is an essential element in fish; however, exposure to high concentrations causes oxidative stress. Water hardness reduces oxidative stress reactions caused by heavy metals. To confirm the effect of water hardness on oxidative stress caused by Zn, goldfish were exposed to various Zn concentrations (1.0, 2.0, and 5.0 mg/L) and water hardness (soft (S), hard (H), and very hard (V)). The activity of superoxide dismutase (SOD) and catalase (CAT) in plasma increased with 1.0, 2.0, and 5.0 mg/L of Zn, and decreased with H and V water hardness. The levels of H₂O₂ and lipid peroxide (LPO) increased with Zn above 1.0 mg/L and decreased with H and V of water hardness. Caspase-9 mRNA expression in the liver increased after 7 and 14 days of Zn exposure and decreased with H and V water hardness. It was confirmed that DNA damage was less dependent on H and V water hardness. Based on the results of this study, at least 1.0 mg/L Zn causes oxidative stress in goldfish, and a high level of apoptosis occurs when exposed for more than 7 days. It appears that the oxidative stress generated by Zn can be alleviated by water hardness of at least 270 mg/L CaCO₃. This study provides information on the relationship between the antioxidant response caused by heavy metals and water hardness in fish.

The Protective Role of Glutathione on Zinc-Induced Neuron Death after Brain Injuries

Glutathione (GSH) is necessary for maintaining physiological antioxidant function, which is responsible for maintaining free radicals derived from reactive oxygen species at low levels and is associated with improved cognitive performance after brain injury. GSH is produced by the linkage of tripeptides that consist of glutamic acid, cysteine, and glycine. The adequate supplementation of GSH has neuroprotective effects in several brain injuries such as cerebral ischemia, hypoglycemia, and traumatic brain injury. Brain injuries produce an excess of reactive oxygen species through complex biochemical cascades, which exacerbates primary neuronal damage. GSH concentrations are known to be closely correlated with the activities of certain genes such as excitatory amino acid carrier 1 (EAAC1), glutamate transporter-associated protein 3-18 (Gtrap3-18), and zinc transporter 3 (ZnT3). Following brain-injury-induced oxidative stress, EAAC1 function is negatively impacted, which then reduces cysteine absorption and impairs neuronal GSH synthesis. In these circumstances, vesicular zinc is also released into the synaptic cleft and then translocated into postsynaptic neurons. The excessive influx of zinc inhibits glutathione reductase, which inhibits GSH's antioxidant functions in neurons, resulting in neuronal damage and ultimately in the impairment of cognitive function. Therefore, in this review, we explore the overall relationship between zinc and GSH in terms of oxidative stress and neuronal cell death. Furthermore, we seek to understand how the modulation of zinc can rescue brain-insult-induced neuronal death after ischemia, hypoglycemia, and traumatic brain injury.

Ototoxicity of Triclosan: A Rat Model Study

OBJECTIVE

Triclosan is utilized as an antibacterial factor in many industrial products. Although there are many toxic features of triclosan in the literature, there is no study on the effect of triclosan on hearing. The purpose of this study is to determine the effect of triclosan on hearing in rats.

METHODS

In this prospective, experimental animal study, 40 healthy Sprague-Dawley rats with normal response to the distortion-product otoacoustic emission (DPOAE) measurements were divided into four groups. Group 1, as the control group, was given only corn oil, group 2 was given 5 mg/kg triclosan dissolved in corn oil, group 3 was given 10 mg/kg triclosan dissolved in corn oil, and group 4 was given 100 mg/kg triclosan dissolved in corn oil; triclosan and corn oil were administered by oral gavage to all groups.

RESULTS

 In our study, low-dose triclosan did not cause hearing loss, but hearing loss was observed in the group that was given high-dose triclosan (100 mg/kg).

CONCLUSION

These findings suggest that triclosan causes hearing loss in rats. This issue should be investigated further to avoid triclosan ototoxicity in humans.

Antibacterial Activity of Two Zn-MOFs Containing a Tricarboxylate Linker

Metal-organic frameworks (MOFs) can be used as reservoirs of metal ions with relevant antibacterial effects. Here, two novel Zn-based MOFs with the formulas [Zn4(μ4-O)(μ-FA)L2] (GR-MOF-8) and [Zn4(μ4-O)L2(H2O)] (GR-MOF-9) (H3L: 5-((4-carboxyphenyl)ethynyl) in isophthalic acid and FA (formate anion) were solvothermally synthetized and fully characterized. The antibacterial activity of GR-MOF-8 and 9 was investigated against Staphylococcus aureus (SA) and Escherichia Coli (EC) by the agar diffusion method. Both bacteria are among the most relevant human and animal pathogens, causing a wide variety of infections, and are often related with the development of antimicrobial resistances. While both Zn-based materials exhibited antibacterial activity against both strains, GR-MOF-8 showed the highest inhibitory action, likely due to a more progressive Zn release under the tested experimental conditions. This is particularly evidenced in the inhibition of SA, with an increasing effect of GR-MOF-8 with time, which is of great significance to ensure the disappearance of the microorganism.

Melatonin Protects Against Titanium Oxide-Induced Neurotoxicity: Neurochemical, Neurobehavioral, and Histopathological Evidences

titania (titanium dioxide, TiO₂) is known to induce neurotoxicity and CNS dysfunctions. Numerous studies have explored the neuroprotective effects of melatonin against neurotoxicity. This study evaluates the potential of melatonin to protect against titania-induced neurotoxicity and the role of the Keap1/Nrf2/ARE signaling pathway. One group of animals were treated with Titania (0.045 and 0.075 g/rat) alone while the other with added melatonin (1 mg/kg and 3 mg/kg) and behavioral alterations were assessed using OFT (open field test). Neurochemical and histopathological changes were also studied in the hippocampus by analyzing kelch ECH associating protein 1 (Keap1), nuclear factor erythroid 2-related factor 2 (Nrf2), and antioxidant response element (ARE). It was seen that the animals with added Melatonin had improved behavioral scores in the OFT, like anxiety and motor dysfunction triggered by TiO₂. Melatonin also reduced lipid peroxidation, ROS, GSSG, IL1β, TNFα, Bax, and Keap1 levels, but boosted GSH, GPx, GR, SOD,IL10,IL4, Bcl2, Nrf2, and ARE levels and improved quadruple mitochondrial enzyme complex activity in titania-treated animals. Histopathological examination showed melatonin induced cytoprotection against vacuolization and necrosis in granular cells of DG and pyramidal cells of CA1 area of the hippocampus. In our study, pretreatment with melatonin reduced titania-induced neurotoxicity in the hippocampus through a mechanism potentially mediated by the Keap-1/Nrf2/ARE pathway.

Bio-Inspired Smart Nanoparticles in Enhanced Cancer Theranostics and Targeted Drug Delivery

Globally, a significant portion of deaths are caused by cancer.Compared with traditional treatment, nanotechnology offers new therapeutic options for cancer due to its ability to selectively target and control drug release. Among the various routes of nanoparticle synthesis, plants have gained significant recognition. The tremendous potential of medicinal plants in anticancer treatments calls for a comprehensive review of existing studies on plant-based nanoparticles. The study examined various metallic nanoparticles obtained by green synthesis using medicinal plants. Plants contain biomolecules, secondary metabolites, and coenzymes that facilitate the reduction of metal ions into nanoparticles. These nanoparticles are believed to be potential antioxidants and cancer-fighting agents. This review aims at the futuristic intuitions of biosynthesis and applications of plant-based nanoparticles in cancer theranostics.

The crosstalk effect between ferrous and other ions metabolism in ferroptosis for therapy of cancer

Ferroptosis is an iron-dependent cell death process characterized by excessive accumulation of reactive oxygen species and lipid peroxidation. The elucidation of ferroptosis pathways may lead to novel cancer therapies. Current evidence suggests that the mechanism of ferroptosis can be summarized as oxidative stress and antioxidant defense mechanisms. During this process, ferrous ions play a crucial role in cellular oxidation, plasma membrane damage, reactive oxygen species removal imbalance and lipid peroxidation. Although, disregulation of intracellular cations (Fe²⁺, Ca²⁺, Zn²⁺, etc.) and anions (Cl^-, etc.) have been widely reported to be involved in ferroptosis, their specific regulatory mechanisms have not been established. To further understand the crosstalk effect between ferrous and other ions in ferroptosis, we reviewed the ferroptosis process from the perspective of ions metabolism. In addition, the role of ferrous and other ions in tumor therapy is briefly summarized.

Continuous antimicrobial mechanism of dispersible hydroxyapatite nanoparticles doped with zinc ions for percutaneous device coatings

Percutaneous devices-indwelling catheters-related infections are serious clinical incidents. It is accordingly necessary to develop anti-infective coating materials suitable for the devices for long-term effectiveness. In our research group, highly dispersible and crystalline hydroxyapatite (HAp) nanoparticles doped with metallic or halogen ions possessing antibacterial activities have been developed. In this study, antibacterial, dispersible, and crystalline zinc (Zn)-doped hydroxyapatite [Zn(15)-HAp] nanoparticles substituted with 13.5% Zn content [Zn/(Zn + Ca) × 100] were prepared by a wet chemical method using an anti-sintering agent through calcination. Antibacterial activities of Zn(15)-HAp nanoparticles were evaluated using Escherichia coli (E. coli) and Staphylococcus aureus. The survival rates of the bacteria on Zn(15)-HAp nanoparticles were significantly lower than that on normal HAp (nHAp) coated surfaces, while no influences were observed on proliferation of L929 cells. Even after soaking Zn(15)-HAp nanoparticles in PBS for 2 weeks, the antibacterial activities against E. coli were maintained at a similar level to a 20 min soaking. The bacterial death was related to not only ion-exchange phenomenon between Zn and magnesium ions but also accumulation of reactive oxygen species (ROS) in the cells. Allergic-like reactions-anaphylactoid reactions-might not readily occur with Zn(15)-HAp nanoparticles because the amounts of histamine released from HMC-1 cells co-cultured with nanoparticles were not significantly different to that of nHAp, but were statistically much lower than that of chlorhexidine.

Cracking the immune fingerprint of metal-organic frameworks

The human body is in a never-ending chess game against pathogens. When the immune system, our natural defence tool, is weakened, these organisms are able to escape, overcoming the body's contingency plan, which results in the body going into a pathological state. To overcome this checkmate status, emerging nanomedicines have been successfully employed as one of the best tactics for boosting the immune response, manipulating the body's defence tools for the specific recognition/elimination of pathological cells via the active ingredient delivery. However, the vast majority of these drug-delivery systems (DDS) are considered to be exclusively passive vehicles, with nanoscale metal-organic frameworks (nanoMOFs) attracting a great deal of attention due to their versatility and ability to carry and deliver exceptional drug payloads and to modulate their biological bypass. Nonetheless, their intrinsic immunogenicity character has been never addressed. Considering the immense possibilities that nanoMOFs offer as a treatment platform, the present study aimed to unveil the immunological fingerprint of MOFs, including an in-deep evaluation of the cellular oxidation balance, the inflammation and recruitment of immune cells and the precise Th1/Th2 cytokine profile that is triggered. This study aims to gain insights that will make more feasible the design of customized immune-active MOF nanoplatforms according to targeted diseases, as the next ace up immune system sleeve.

Zinc induces reactive astrogliosis through ERK-dependent activation of Stat3 and promotes synaptic degeneration

Reactive astrogliosis is an early event in Alzheimer's disease (AD) brain and plays a key role in synaptic degeneration in AD development. Zinc accumulates in extracellular fraction and synaptosomes in AD human brains with its effect on reactive astrocytes remaining unknown. Through Western blotting, Quantitative polymerase chain reaction (qPCR), and immunofluorescence detection on primary astrocytes treated by zinc and/or zinc chelator, we revealed that zinc induced harmful A1-type reactive astrogliosis in cultured primary astrocytes; the latter, promoted synaptic degeneration in primary neurons. The mechanism investigation showed that zinc induced activation of extracellular regulated protein kinase (ERK) and Janus kinase 2 (JAK2), which phosphorylated signal transduction and transcription activator 3 (Stat3) at serine 727 (S727-Stat3) and tyrosine 705 (Y705-Stat3), respectively, resulting in activation of Stat3. Stat3 phosphorylation at S727 by ERK plays a key role in zinc-induced astrogliosis. These data imply a new molecular mechanism of reactive astrogliosis in AD, in which excessive zinc activates Stat3 through up-regulating ERK signaling pathway.

Super-assembled silica nanoprobes for intracellular Zn(II) sensing and reperfusion injury treatment through in situ MOF crystallization

The production of excess free zinc ions (Zn²⁺) in cells has been identified as an important cause of cell injury or apoptosis after ischemia reperfusion. Thus, developing a nanosystem with multiple therapeutic functions to significantly eliminate multiple cell injury factors is of great interest. Here, a super-assembled nanosystem consisting of a polyethylene glycol (PEG) surface-modified mesoporous silica nanoparticle (MSN) encapsulating 2-methylimidazole (2MI) and a Zn²⁺ probe (PZn) was fabricated. The 2MI-P@MSN nanoassemblies showed a "turn-on" fluorescence signal at 476 nm toward zinc ions due to the presence of PZn. Besides, zeolitic imidazolate framework-8 (ZIF-8) could be assembled on the site intracellularly after 2MI chelating with free zinc ions. The experimental results revealed that 2MI-P@MSN exhibited excellent biocompatibility and non-cytotoxicity, and was able to provide satisfactory protection to OGD/R-treated cells based on zinc ion adsorption and the antioxidant effect of ZIF-8, which could effectively improve the survival rate of reperfusion injury cells from 52% to 73%. Notably, selective and quantitative sensing of Zn²⁺ was successfully carried out in the cells. This strategy highlights the potential of the detection, absorption and assembly of excess zinc ions simultaneously for cell therapy, which provides a promising therapeutic method for ischemic stroke, oxidative damage and diseases associated with zinc ion accumulation.

A Systematic Review of Biosynthesized Metallic Nanoparticles as a Promising Anti-Cancer-Strategy

Cancer is one of the foremost causes of death worldwide. Cancer develops because of mutation in genes that regulate normal cell cycle and cell division, thereby resulting in uncontrolled division and proliferation of cells. Various drugs have been used to treat cancer thus far; however, conventional chemotherapeutic drugs have lower bioavailability, rapid renal clearance, unequal delivery, and severe side effects. In the recent years, nanotechnology has flourished rapidly and has a multitude of applications in the biomedical field. Bio-mediated nanoparticles (NPs) are cost effective, safe, and biocompatible and have got substantial attention from researchers around the globe. Due to their safe profile and fewer side effects, these nanoscale materials offer a promising cure for cancer. Currently, various metallic NPs have been designed to cure or diagnose cancer; among these, silver (Ag), gold (Au), zinc (Zn) and copper (Cu) are the leading anti-cancer NPs. The anticancer potential of these NPs is attributed to the production of reactive oxygen species (ROS) in cellular compartments that eventually leads to activation of autophagic, apoptotic and necrotic death pathways. In this review, we summarized the recent advancements in the biosynthesis of Ag, Au, Zn and Cu NPs with emphasis on their mechanism of action. Moreover, nanotoxicity, as well as the future prospects and opportunities of nano-therapeutics, are also highlighted.

Antimicrobial Effect of Chitosan Films on Food Spoilage Bacteria

Synthetic materials commonly used in the packaging industry generate a considerable amount of waste each year. Chitosan is a promising feedstock for the production of functional biomaterials. From a biological point of view, chitosan is very attractive for food packaging. The purposes of this study were to evaluate the antibacterial activity of a set of chitosan-metal oxide films and different chitosan-modified graphene (oxide) films against two foodborne pathogens: Campylobacter jejuni ATCC 33560 and Listeria monocytogenes 19115. Moreover, we wanted to check whether the incorporation of antimicrobial constituents such as TiO2, ZnO, Fe2O3, Ag, and graphene oxide (GO) into the polymer matrices can improve the antibacterial properties of these nanocomposite films. Finally, this research helps elucidate the interactions of these materials with eukaryotic cells. All chitosan-metal oxide films and chitosan-modified graphene (oxide) films displayed improved antibacterial (C. jejuni ATCC 33560 and L. monocytogenes 19115) properties compared to native chitosan films. The CS-ZnO films had excellent antibacterial activity towards L. monocytogenes (90% growth inhibition). Moreover, graphene-based chitosan films caused high inhibition of both tested strains. Chitosan films with graphene (GO, GOP, GOP-HMDS, rGO, GO-HMDS, rGOP), titanium dioxide (CS-TiO2 20:1a, CS-TiO2 20:1b, CS-TiO2 2:1, CS-TiO2 1:1a, CS-TiO2 1:1b) and zinc oxide (CS-ZnO 20:1a, CS-ZnO 20:1b) may be considered as a safe, non-cytotoxic packaging materials in the future.

HDAC6 inhibitors sensitize non-mesenchymal triple-negative breast cancer cells to cysteine deprivation

Triple-negative breast cancer (TNBC) is a highly malignant type of breast cancer and lacks effective therapy. Targeting cysteine-dependence is an emerging strategy to treat the mesenchymal TNBC. However, many TNBC cells are non-mesenchymal and unresponsive to cysteine deprivation. To overcome such resistance, three selective HDAC6 inhibitors (Tubacin, CAY10603, and Tubastatin A), identified by epigenetic compound library screening, can synergize with cysteine deprivation to induce cell death in the non-mesenchymal TNBC. Despite the efficacy of HDAC6 inhibitor, knockout of HDAC6 did not mimic the synthetic lethality induced by its inhibitors, indicating that HDAC6 is not the actual target of HDAC6 inhibitor in this context. Instead, transcriptomic profiling showed that tubacin triggers an extensive gene transcriptional program in combination with erastin, a cysteine transport blocker. Notably, the zinc-related gene response along with an increase of labile zinc was induced in cells by the combination treatment. The disturbance of zinc homeostasis was driven by PKCγ activation, which revealed that the PKCγ signaling pathway is required for HDAC6 inhibitor-mediated synthetic lethality. Overall, our study identifies a novel function of HDAC6 inhibitors that function as potent sensitizers of cysteine deprivation and are capable of abolishing cysteine-independence in non-mesenchymal TNBC.

Role of zinc in female reproduction

Zinc is a critical component in a number of conserved processes that regulate female germ cell growth, fertility, and pregnancy. During follicle development, a sufficient intracellular concentration of zinc in the oocyte maintains meiotic arrest at prophase I until the germ cell is ready to undergo maturation. An adequate supply of zinc is necessary for the oocyte to form a fertilization-competent egg as dietary zinc deficiency or chelation of zinc disrupts maturation and reduces the oocyte quality. Following sperm fusion to the egg to initiate the acrosomal reaction, a quick release of zinc, known as the zinc spark, induces egg activation in addition to facilitating zona pellucida hardening and reducing sperm motility to prevent polyspermy. Symmetric division, proliferation, and differentiation of the preimplantation embryo rely on zinc availability, both during the oocyte development and post-fertilization. Further, the fetal contribution to the placenta, fetal limb growth, and neural tube development are hindered in females challenged with zinc deficiency during pregnancy. In this review, we discuss the role of zinc in germ cell development, fertilization, and pregnancy with a focus on recent studies in mammalian females. We further detail the fundamental zinc-mediated reproductive processes that have only been explored in non-mammalian species and speculate on the role of zinc in similar mechanisms of female mammals. The evidence collected over the last decade highlights the necessity of zinc for normal fertility and healthy pregnancy outcomes, which suggests zinc supplementation should be considered for reproductive age women at risk of zinc deficiency.

Taurine Increases Zinc Preconditioning-Induced Prevention of Nitrosative Stress, Metabolic Alterations, and Motor Deficits in Young Rats following Intrauterine Ischemia

Oxygen deprivation in newborns leads to hypoxic-ischemic encephalopathy, whose hallmarks are oxidative/nitrosative stress, energetic metabolism alterations, nutrient deficiency, and motor behavior disability. Zinc and taurine are known to protect against hypoxic-ischemic brain damage in adults and neonates. However, the combined effect of prophylactic zinc administration and therapeutic taurine treatment on intrauterine ischemia- (IUI-) induced cerebral damage remains unknown. The present work evaluated this issue in male pups subjected to transient IUI (10 min) at E17 and whose mothers received zinc from E1 to E16 and taurine from E17 to postnatal day 15 (PND15) via drinking water. We assessed motor alterations, nitrosative stress, lipid peroxidation, and the antioxidant system comprised of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Enzymes of neuronal energetic pathways, such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH), were also evaluated. The hierarchization score of the protective effect of pharmacological strategies (HSPEPS) was used to select the most effective treatment. Compared with the IUI group, zinc, alone or combined with taurine, improved motor behavior and reduced nitrosative stress by increasing SOD, CAT, and GPx activities and decreasing the GSSG/GSH ratio in the cerebral cortex and hippocampus. Taurine alone increased the AST/ALT, LDH/ALT, and AST/LDH ratios in the cerebral cortex, showing improvement of the neural bioenergetics system. This result suggests that taurine improves pyruvate, lactate, and glutamate metabolism, thus decreasing IUI-caused cerebral damage and relieving motor behavior impairment. Our results showed that taurine alone or in combination with zinc provides neuroprotection in the IUI rat model.

The Multifaceted Roles of Zinc in Neuronal Mitochondrial Dysfunction

Zinc is a highly abundant cation in the brain, essential for cellular functions, including transcription, enzymatic activity, and cell signaling. However, zinc can also trigger injurious cascades in neurons, contributing to the pathology of neurodegenerative diseases. Mitochondria, critical for meeting the high energy demands of the central nervous system (CNS), are a principal target of the deleterious actions of zinc. An increasing body of work suggests that intracellular zinc can, under certain circumstances, contribute to neuronal damage by inhibiting mitochondrial energy processes, including dissipation of the mitochondrial membrane potential (MMP), leading to ATP depletion. Additional consequences of zinc-mediated mitochondrial damage include reactive oxygen species (ROS) generation, mitochondrial permeability transition, and excitotoxic calcium deregulation. Zinc can also induce mitochondrial fission, resulting in mitochondrial fragmentation, as well as inhibition of mitochondrial motility. Here, we review the known mechanisms responsible for the deleterious actions of zinc on the organelle, within the context of neuronal injury associated with neurodegenerative processes. Elucidating the critical contributions of zinc-induced mitochondrial defects to neurotoxicity and neurodegeneration may provide insight into novel therapeutic targets in the clinical setting.

Non-Cell-Autonomous Regulation of Optic Nerve Regeneration by Amacrine Cells

Visual information is conveyed from the eye to the brain through the axons of retinal ganglion cells (RGCs) that course through the optic nerve and synapse onto neurons in multiple subcortical visual relay areas. RGCs cannot regenerate their axons once they are damaged, similar to most mature neurons in the central nervous system (CNS), and soon undergo cell death. These phenomena of neurodegeneration and regenerative failure are widely viewed as being determined by cell-intrinsic mechanisms within RGCs or to be influenced by the extracellular environment, including glial or inflammatory cells. However, a new concept is emerging that the death or survival of RGCs and their ability to regenerate axons are also influenced by the complex circuitry of the retina and that the activation of a multicellular signaling cascade involving changes in inhibitory interneurons - the amacrine cells (AC) - contributes to the fate of RGCs. Here, we review our current understanding of the role that interneurons play in cell survival and axon regeneration after optic nerve injury.

Zinc regulates reactive oxygen species generation in platelets

Vascular complications resulting from atherosclerosis development are a major cause of death. Reactive oxygen species (ROS) are produced by platelets during activation, and have been demonstrated to positively regulate platelet activatory responses. Zn2+ is also an important hemostatic cofactor in platelets, acting both as a platelet agonist and second messenger. Whilst the effect of Zn2+-dependent signaling mechanisms on ROS production in nucleated cells has been demonstrated, comparable roles in platelets have yet to be investigated. In this study we investigated the relationship between fluctuations in cytosolic Zn2 [Zn2+]i and platelet ROS production. Agonist-evoked ROS production, GSH levels and GPx activity are abrogated in platelets treated with the Zn2+-chelator, TPEN. Conversely, increasing platelet [Zn2+]i using Zn2+ ionophores potentiated ROS generation and decreased GSH levels and GPx activity. Zn2+-dependent ROS production was sensitive to pretreatment with DPI or mitoTEMPO, NADPH oxidase and mitochondria inhibitors respectively. Increasing [Zn2+]i resulted in increases of Erk1/2 and JNK phosphorylation. Our data are consistent with a functional association between [Zn2+]i and ROS production in platelets that could influence thrombus formation in a clinical context.

ZIF-8 nano confined protein-titanocene complex core-shell MOFs for efficient therapy of Neuroblastoma: Optimization, molecular dynamics and toxicity studies

In the present study, we have developed the core-shell metal organic framework (MOF) of zinc, wherein titanocene dichloride (TC) loaded lactoferrin (Lf) functioned as a core. The complexation of TC to Lf was studies using molecular dynamics study, Quantum mechanical model and spectroscopic investigations. Plackett-Burman design was used to screen and select the critical factors affecting the responses (size, zeta potential and PDI) while the effect of those parameter on the quality attributes (size and yield) was studied by means of a Box-Behnken design. The optimised Lf-TC nanoparticles were loaded inside the ZIF-8 framework along with an anticancer agent 5 Fluorouracil and characterized using techniques like FTIR, PXRD, Raman spectroscopy, EDX and UV-NIR spectroscopy and morphological techniques like SEM, TEM, AFM. The compatibility of the loaded ZIF-8 framework was examined by haemocompatibility studies. The potential of developed nanoplatform against Neuroblastoma was assessed using a cell line studies along with in vivo toxicity studies to ascertain its safety for after in-vivo administration in Wistar rats. Therefore, we can conclude that by employing the approach of DOE we were able to optimize the size and yield of Lf-TC NPs and further by loading inside ZIF-8 framework along with an anticancer drug like 5 fluorouracil we were able to develop a potential nanoplatform for the multimodal therapy of Neuroblastoma.

Gene Expression Changes after Parental Exposure to Metals in the Sea Urchin Affect Timing of Genetic Programme of Embryo Development

It is widely accepted that phenotypic traits can be modulated at the epigenetic level so that some conditions can affect the progeny of exposed individuals. To assess if the exposure of adult animals could result in effects on the offspring, the Mediterranean sea urchin and its well-characterized gene regulatory networks (GRNs) was chosen as a model. Adult animals were exposed to known concentrations of zinc and cadmium (both individually and in combination) for 10 days, and the resulting embryos were followed during the development. The oxidative stress occurring in parental gonads, embryo phenotypes and mortality, and the expression level of a set of selected genes, including members of the skeletogenic and endodermal GRNs, were evaluated. Increased oxidative stress at F₀, high rates of developmental aberration with impaired gastrulation, in association to deregulation of genes involved in skeletogenesis (dri, hex, sm50, p16, p19, msp130), endodermal specification (foxa, hox11/13b, wnt8) and epigenetic regulation (kat2A, hdac1, ehmt2, phf8 and UBE2a) occurred either at 24 or 48 hpf. Results strongly indicate that exposure to environmental pollutants can affect not only directly challenged animals but also their progeny (at least F₁), influencing optimal timing of genetic programme of embryo development, resulting in an overall impairment of developmental success.

The effect of zinc on human trophoblast proliferation and oxidative stress

Adequate Zinc (Zn) intake is required to prevent multiple teratogenic effects however deviations from adequate Zn intake, including high maternal Zn status, have been linked to increased incidence of pregnancy complications, including those associated with inadequate placentation. Using placental trophoblast HTR8/SVneo cells and first trimester human placental explants (n = 12), we assessed the effects of varying Zn concentrations on trophoblast proliferation, viability, apoptosis and oxidative stress. Compared to physiologically normal Zn levels (20 µM), HTR-8/SVneo cell proliferation index was significantly lower in the presence of physiologically elevated (40 µM; P = .020) and supra-physiological (80 µM; P = .007) Zn. The latter was also associated with reduced proliferation (P = .004) and viability (P < .0001) in cultured placental explants, but not apoptosis. Reactive oxygen species production in HTR8/SVneo cultures was significantly higher in the presence of 80 µM Zn compared to all physiologically relevant levels. Oxidative stress, induced by an oxidizing agent menadione, was further exacerbated by high (80 µM) Zn. Zn did not affect lipid peroxidation in either HTR8/SVneo cells or placental explants or antioxidant defense mechanisms that included glutathione reductase and superoxide dismutase. Further study should focus on elucidating mechanisms behind impaired trophoblast proliferation and increased oxidative stress as a result of elevated Zn levels.

Natural Products for the Treatment of Neurodegenerative Diseases

Neurodegenerative diseases are a heterogeneous group of disorders characterized by the progressive degeneration of the structure and function of the central nervous system or peripheral nervous system. Alzheimer's Disease (AD), Parkinson's Disease (PD) and Spinal Cord Injury (SCI) are the common neurodegenerative diseases, which typically occur in people over the age of 60. With the rapid development of an aged society, over 60 million people worldwide are suffering from these uncurable diseases. Therefore, the search for new drugs and therapeutic methods has become an increasingly important research topic. Natural products especially those from the Traditional Chinese Medicines (TCMs), are the most important sources of drugs, and have received extensive interest among pharmacist. In this review, in order to facilitate further chemical modification of those useful natural products by pharmacists, we will bring together recent studies in single natural compound from TCMs with neuroprotective effect.

The Transient Receptor Potential Melastatin 7 (TRPM7) Inhibitors Suppress Seizure-Induced Neuron Death by Inhibiting Zinc Neurotoxicity

Transient receptor potential melastatin 7 (TRPM7) is an ion channel that mediates monovalent cations out of cells, as well as the entry of divalent cations, such as zinc, magnesium, and calcium, into the cell. It has been reported that inhibitors of TRPM7 are neuroprotective in various neurological diseases. Previous studies in our lab suggested that seizure-induced neuronal death may be caused by the excessive release of vesicular zinc and the subsequent accumulation of zinc in the neurons. However, no studies have evaluated the effects of carvacrol and 2-aminoethoxydiphenyl borate (2-APB), both inhibitors of TRPM7, on the accumulation of intracellular zinc in dying neurons following seizure. Here, we investigated the therapeutic efficacy of carvacrol and 2-APB against pilocarpine-induced seizure. Carvacrol (50 mg/kg) was injected once per day for 3 or 7 days after seizure. 2-APB (2 mg/kg) was also injected once per day for 3 days after seizure. We found that inhibitors of TRPM7 reduced seizure-induced TRPM7 overexpression, intracellular zinc accumulation, and reactive oxygen species production. Moreover, there was a suppression of oxidative stress, glial activation, and the blood–brain barrier breakdown. In addition, inhibitors of TRPM7 remarkably decreased apoptotic neuron death following seizure. Taken together, the present study demonstrates that TRPM7-mediated zinc translocation is involved in neuron death after seizure. The present study suggests that inhibitors of TRPM7 may have high therapeutic potential to reduce seizure-induced neuron death.

Detoxification of Cu(II) by the red yeast Rhodotorula mucilaginosa: from extracellular to intracellular

The red yeast (Rhodotorula mucilaginosa: Rho) has abundant extracellular polymeric substances (EPS) and intracellular vesicles (Ves). This study explored the mechanisms of Rho to resist Cu toxicity from extracellular to intracellular, i.e., EPS, membrane, and Ves. The Cu²⁺ concentrations were set from 0 to 200 mg/L. In contrast to other heavy metals (e.g., Pb²⁺), low Cu²⁺ stress has no evident stimulation to EPS production. In particular, GSH content in EPS did not show significant changes. The Cu removal was decreased from ~ 35 to ~ 0% as Cu stress raised from 0 to 200 mg/L, which confirmed the low binding of Cu cations to EPS. Moreover, redox peaks at - 0.35 V (reduction) and - 0.02 V (oxidation) in EPS were observed based on electrochemical analysis. Subsequently, the potential Haber-Weiss reaction in EPS lowered fungal ability to shield against the Cu toxicity. Then, the contrast of Cu concentration between the extracellular and intracellular regions was enlarged. Moreover, the thickness of cell membrane decreased from 450 to 116 nm during the elevation of Cu stress. These accelerated the transport of Cu cations into intracellular, but the redox reaction in both cell membrane and intracellular region was limited. Under transmission electron microscopy, the intracellular Ves showed evident sorption of Cu cations (100 mg/L). However, the Ves started to deform and gradually lost their activity at 200 mg/L. Therefore, this study successfully elucidated the correlated extracellular and intracellular mechanisms of metal detoxification by yeast. KEY POINTS: •This study provides a comprehensive explanation for the invasion of Cu²⁺ into fungal (Rhodotorula mucilaginosa) cells based on microbial physiological and biochemical analysis, electrochemical analysis, and transmitted electron microscopy. •Cu nanoparticles are involved in redox reactions in the EPS, thus greatly reducing the prophase protection for fungal cells by EPS. •At 200 mg/L Cu²⁺ stress, deformation of cell membrane intensifies the contrast of Cu concentrations between extra- and intracellular regions. This further suppresses the transportation of Cu²⁺ by intracellular vesicles. Graphical abstract.

Zinc ameliorates lead toxicity by reducing body Pb burden and restoring Pb-induced haematological and biochemical derangements

Background:

Studies on nutritional factors, including zinc in ameliorating the deleterious effects of potentially toxic elements have been scarce and the findings have been inconsistent.

Aim:

The aim of the present study was to evaluate the ameliorative potential of zinc against lead-induced toxicity in rats.

Materials and methods:

Male albino rats (n = 24) assigned into four groups of six/group: normal control (NC), zinc control (ZnC; 20 mg/kg ZnCl2), lead control (PbC; 50 mg/kg PbCl2) and lead plus zinc (Pb + Zn; 50 mg/kg PbCl2plus 20 mg/kg ZnCl2), respectively were investigated. All administrations were through oral route and lasted for 42 days after which blood samples were collected for haematological and biochemical analyses using standard techniques.

Results:

Results showed that packed cell volume (PCV), haemoglobin concentration (HBC), red blood cell count (RBC) were significant (p < 0.05) reduced while total white blood cell count (TWBC), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) and platelets were significantly elevated in PbC group in comparison with NC and ZnC. Also liver and renal function parameters as well as the liver and kidney malondialdehyde (MDA) were elevated while antioxidant enzymes; catalase (CAT) and superoxide dismutase (SOD) were significantly (p < 0.05) reduced in PbC group in comparison with NC and ZnC. Concentrations of lead were in the order: blood > liver > kidney in the PbC group. In addition to restoration of the altered parameters, administration of zinc in Pb + Zn group significantly reduced the raised lead concentrations in the plasma and organs.

Conclusion:

Reduction in body Pb burden and restoration of Pb-induced derangements in haematological and biochemical parameters by Zn strongly support the ameliorative property of Zn against Pb-induced toxicity.

Deletion of a small, secreted and cysteine-rich protein Cpl1 leads to increased invasive growth of Cryptococcus neoformans into nutrient agar

Invasive growth of yeast cells into nutrient agar is induced by different stresses and contributes to the survival of yeast cells under several adverse conditions. The mechanism of invasive growth of Saccharomyces cerevisiae has been extensively investigated. However, there is very little information about the mechanism of invasive growth of another human pathogen yeast Cryptococcus neoformans. Here, we report that deletion of a small and secreted cysteine-rich protein Cpl1 in C. neoformans JEC21 leads to increased adhesive and invasive growth into nutrient agar. The increased adhesive and invasive growth does not depend on the only known adhesion protein Cfl1 and its main controller Znf2. Cpl1Δ accumulates significantly higher level of intracellular labile zinc ion, leading to increased glucose uptake, higher level of mitochondrial membrane potential, ATP and Reactive Oxygen Species(ROS) production. Higher level of ROS activates Snf1, leading to invasive growth of Cpl1Δ. Three cysteine residues at the N-terminals of the cysteine-rich domain controls the increased invasive growth under nutrient sufficient conditions. This is the first report that a small and secreted cysteine-rich protein negatively regulates invasive growth of C. neoformans through regulating the intracellular labile zinc ion level. The function of this cysteine-rich domain was systematically investigated by site-directed mutagenensis in C. neoformans. The work contributes to understanding the function of this protein family and the invasive growth mechanism in C. neoformans.

Comparing the Influence of High Doses of Different Zinc Salts on Oxidative Stress and Energy Depletion in IPEC-J2 Cells

The current study aimed to investigate the influence of four supplemental zinc salts (chelated: Zn glycine; non-chelated: Zn sulfate, Zn citrate, Zn gluconate) among different zinc concentrations (30-300 μM) on cell proliferation, oxidative stress, and energy depletion in intestinal porcine jejunum epithelial cells (IPEC-J2). Different zinc salts affected cell viability in a time- and dose-dependent manner, which was mainly dependent on the uptake of intracellular Zn²⁺. Intracellular Zn²⁺ of Zn sulfate has taken up almost twice as high as Zn glycine when cells were loaded with 100-200 μM zinc. After loading cells with 300 μM zinc, Zn glycine and Zn sulfate had a similar trend in accumulation of Zn²⁺. When the intracellular Zn²⁺ overloads, cells will gradually be damaged and subsequently die bearing biochemical features of necrosis or late apoptosis. Meanwhile, obviously, increased levels of intracellular ROS, mitochondrial ROS, MDA, and NO and decreased levels of GSH were observed. Excessive intracellular Zn²⁺ significantly decreased mitochondria membrane potential accompanied by an obvious loss of ATP and NAD⁺ levels. Overall, exposure to high doses of zinc salts caused cell damage, which was mainly dependent on the uptake of Zn²⁺. Zinc overload induced oxidative stress and energy depletion in IPEC-J2 cells, and the cell damage with non-chelated zinc addition was more serious than Zn glycine.

Neuronal life or death linked to depression treatment: the interplay between drugs and their stress-related outcomes relate to single or combined drug therapies

Depression is a serious medical condition, typically treated by antidepressants. Conventional monotherapy can be effective only in 60–80% of patients, thus modern psychiatry deals with the challenge of new methods development. At the same moment, interactions between antidepressants and the occurrence of potential side effects raise serious concerns, which are even more exacerbated by the lack of relevant data on exact molecular mechanisms. Therefore, the aims of the study were to provide up-to-date information on the relative mechanisms of action of single antidepressants and their combinations. In this study, we evaluated the effect of single and combined antidepressants administration on mouse hippocampal neurons after 48 and 96 h in terms of cellular and biochemical features in vitro. We show for the first time that co-treatment with amitriptyline/imipramine + fluoxetine initiates in cells adaptation mechanisms which allow cells to adjust to stress and finally exerts less toxic events than in cells treated with single antidepressants. Antidepressants treatment induces in neuronal cells oxidative and nitrosative stress, which leads to micronuclei and double-strand DNA brakes formation. At this point, two different mechanistic events are initiated in cells treated with single and combined antidepressants. Single antidepressants (amitriptyline, imipramine or fluoxetine) activate cell cycle arrest resulting in proliferation inhibition. On the other hand, treatment with combined antidepressants (amitriptyline/imipramine + fluoxetine) initiates p16-dependent cell cycle arrest, overexpression of telomere maintenance proteins and finally restoration of proliferation. In conclusion, our findings may pave the way to better understanding of the stress-related effects on neurons associated with mono- and combined therapy with antidepressants.

Toxicity of Carbon, Silicon, and Metal-Based Nanoparticles to the Hemocytes of Three Marine Bivalves

Simple Summary

The growing nanotechnology industry disposes of a variety of nanoparticles with different physiochemical properties in everyday life. However, the dependence of the safety and toxicity of nanoparticles on their physicochemical properties remains unclear. Bivalve molluscs represent an efficient model for the investigation of nanoparticle toxicity owing to their filtrating ability and feeding on particles suspended in the water. Moreover, the blood cells of bivalve molluscs, the hemocytes, have been suggested as a good analog test-object to mammalian immune cells, phagocytes. In this study, we used hemocytes of three marine bivalve species, namely, Crenomytilus grayanus, Modiolus modiolus, and Arca boucardi, to evaluate and compare the toxic effects of 10 different types of nanoparticles. We gave short-term exposure of the nanoparticles to the hemocytes and registered viability and changes in their cell membrane polarization by employing flow cytometry. Metal-based nanoparticles were the most toxic to the cells of all three tested bivalve mollusc species. However, the sensitivity to different nanoparticle types varied between species. Moreover, the registered cell membrane depolarization indicated an early toxic response and raised concern that chronic long-term exposure of nanoparticles (even if they were previously declared as safe) is a serious threat for aquatic organisms.

Abstract

Nanoparticles (NPs) have broad applications in medicine, cosmetics, optics, catalysis, environmental purification, and other areas nowadays. With increasing annual production of NPs, the risks of their harmful influence on the environment and human health are also increasing. Currently, our knowledge about the mechanisms of the interaction between NPs and living organisms is limited. The marine species and their habitat environment are under continuous stress owing to the anthropogenic activities, which result in the release of NPs in the aquatic environment. We used a bioassay model with hemocytes of three bivalve mollusc species, namely, Crenomytilus grayanus, Modiolus modiolus, and Arca boucardi, to evaluate the toxicity of 10 different types of NPs. Specifically, we compared the cytotoxic effects and cell-membrane polarization changes in the hemocytes exposed to carbon nanotubes, carbon nanofibers, silicon nanotubes, cadmium and zinc sulfides, Au-NPs, and TiO₂ NPs. Viability and the changes in hemocyte membrane polarization were measured by the flow cytometry method. The highest aquatic toxicity was registered for metal-based NPs, which caused cytotoxicity to the hemocytes of all the studied bivalve species. Our results also highlighted different sensitivities of the used tested mollusc species to specific NPs.

Identification and biochemical characterization of the glutathione reductase family from Populus trichocarpa

Glutathione reductase (GR; EC 1.6.4.2) is a key NADPH-dependent flavo-protein oxidoreductase which can catalyze the oxidized glutathione (GSSG) to reduced glutathione (GSH) to protect plant cells from oxidative damage induced by Reactive oxygen species (ROS) burst. To investigate the biochemical characteristics and functional divergence of Populus GR family, three GR genes (PtGR1.1/1.2/2) were cloned from Populus trichocarpa and their biochemical characteristics were analyzed in this study. All the three genes were expressed in root, stem, leaf and bud, and the expression of PtGR genes were general upregulated under salicylic acid and alamethicin treatment. PtGR1.1 and PtGR1.2 were localized in cytoplasm, while PtGR2 was in chloroplast. The three PtGR proteins showed different enzymatic activities, apparent kinetic characteristic and thermal stability profiles. However, they have similar bivalent metal ions (Cu²⁺, Cd²⁺, Zn²⁺ and Pb²⁺) sensitivity and optimum pH profiles. Our study sheds light on a comprehensive information of glutathione reductase family in P. trichocarpa, and proved PtGR genes play critical roles when suffering different stresses.

Non-redox cycling mechanisms of oxidative stress induced by PM metals

Metallic compounds contribute to the oxidative stress of ambient particulate matter (PM) exposure. The toxicity of redox inert ions of cadmium, mercury, lead and zinc, as well as redox-active ions of vanadium and chromium is underlain by dysregulation of mitochondrial function and loss of signaling quiescence. Central to the initiation of these effects is the interaction of metal ions with cysteinyl thiols on glutathione and key regulatory proteins, which leads to impaired mitochondrial electron transport and persistent pan-activation of signal transduction pathways. The mitochondrial and signaling effects are linked by the production of H₂O₂, generated from mitochondrial superoxide anion or through the activation of NADPH oxidase, which extends the range and amplifies the magnitude of the oxidative effects of the metals. This oxidative burden can be further potentiated by inhibitory effects of the metals on the enzymes of the glutathione and thioredoxin systems. Along with the better-known Fenton-based mechanisms, the non-redox cycling mechanisms of oxidative stress induced by metals constitute significant pathways for cellular injury induced by PM inhalation.

Antimicrobial Activity and Prevention of Bacterial Biofilm Formation of Silver and Zinc Oxide Nanoparticle-Containing Polyester Surfaces at Various Concentrations for Use

Food contact surfaces are primary sources of bacterial contamination in food industry processes. With the objective of preventing bacterial adhesion and biofilm formation on surfaces, this study evaluated the antimicrobial activity of silver (Ag-NPs) and zinc oxide (ZnO-NPs) nanoparticle-containing polyester surfaces (concentration range from 400 ppm to 850 ppm) using two kinds of bacteria, Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli), and the prevention of bacterial biofilm formation using the pathogen Listeria monocytogenes. The results of antimicrobial efficacy (reductions ≥ 2 log CFU/cm2) showed that at a concentration of 850 ppm, ZnO-NPs were effective against only E. coli (2.07 log CFU/cm2). However, a concentration of 400 ppm of Ag-NPs was effective against E. coli (4.90 log CFU/cm2) and S. aureus (3.84 log CFU/cm2). Furthermore, a combined concentration of 850 ppm Ag-NPs and 400 ppm ZnO-NPs showed high antimicrobial efficacy against E. coli (5.80 log CFU/cm2) and S. aureus (4.11 log CFU/cm2). The results also showed a high correlation between concentration levels and the bacterial activity of Ag-ZnO-NPs (R2 = 0.97 for S. aureus, and R2 = 0.99 for E. coli). They also showed that unlike individual action, the joint action of Ag-NPs and ZnO-NPs has high antimicrobial efficacy for both types of microorganisms. Moreover, Ag-NPs prevent the biofilm formation of L. monocytogenes in humid conditions of growth at concentrations of 500 ppm. Additional studies under different conditions are needed to test the durability of nanoparticle containing polyester surfaces with antimicrobial properties to optimize their use.

[Brain zinc dyshomeostasis and glial cells in ischemic stroke]

Zinc, an essential trace element, plays an important role in a large number of biological functions. In mammalian brain, whereas the majority of brain zinc is bound to proteins including metallothionein, about 5-15% is stored in presynaptic vesicles of glutamatergic neurons throughout the forebrain, especially in the hippocampus, in a relatively free state. Thus, free zinc (Zn²⁺) concentration in the brain is considered to be regulated in order to maintain normal brain functions such as learning and memory. On the other hand, brain Zn²⁺ dyshomeostasis has been recognized as a mechanism for neuronal injury in brain disorders including Alzheimer's disease and brain ischemia. In particular, after transient brain ischemia, Zn²⁺ accumulates in hippocampal neurons via a zinc transport system, or via release from cytosolic zinc-binding proteins, which results in neuronal cell death. Recently, it has been demonstrated that Zn²⁺ dyshomeostasis also occurs in glial cells such as microglia, astrocytes and oligodendrocytes after brain ischemia. In oligodendrocytes, ischemic insult triggers intracellular Zn²⁺ accumulation, resulting in cell death via mitochondrial dysfunction. Increased extracellular Zn²⁺ inhibits astrocytic glutamate uptake. In addition, extracellular Zn²⁺ massively released from ischemic neurons primes microglia to enhance production of pro-inflammatory cytokines in response to stimuli that trigger M1 activation. This review aims to describe the impact of brain Zn²⁺ dyshomeostasis on alterations in glial cell survival and functions in post-ischemic brains.

Exploring the cytotoxic activity of new phenanthroline salicylaldimine Zn(II) complexes

Zinc(II) complexes bearing N-salicylideneglycinate (Sal-Gly) and 1,10-phenanthroline (phen) or phenanthroline derivatives [NN = 5-chloro-1,10-phenanthroline, 5-amine-1,10-phenanthroline (amphen), 4,7-diphenyl-1,10-phenanthroline (Bphen) and 5,6-epoxy-5,6-dihydro-1,10-phenanthroline] are synthesized. Complexes formulated as [Zn(NN)₂(H₂O)₂]²⁺(NN = phen and amphen), are also prepared. The cytotoxicity of the compounds is evaluated towards a panel of human cancer cells: ovarian (A2780), breast (MCF7) and cervical (HeLa), as well as non-tumoral V79 fibroblasts. All compounds display higher cytotoxicity than cisplatin (IC₅₀ = 22.5 ± 5.0 μM) towards ovarian cells, showing IC₅₀values in the low micromolar range. Overall, all compounds show higher selectivity for the A2780 cells than for the non-tumoral cells and higher selectivity indexes (IC₅₀(V79)/IC₅₀(A2780) than cisplatin. [Zn(Sal-Gly)(NN)(H₂O)] complexes induce caspase-dependent apoptosis in A2780 cells, except [Zn(Sal-Gly)(Bphen)(H₂O)], one of the most cytotoxic of the series. The cellular uptake in the ovarian cells analyzed by Inductively Coupled Plasma mass spectrometry indicates different Zn distribution profiles. Transmission electronic microscopy shows mitochondria alterations and apoptotic features consistent with caspase activation; cells incubated with [Zn(Sal-Gly)(amphen)(H₂O)] present additional nuclear membrane alterations in agreement with significant association with the nucleus. The increase of reactive oxygen species and lipid peroxidation forms could be related to apoptosis induction. [Zn(NN)₂(H₂O)₂]²⁺complexes have high ability to bind DNA through intercalation/groove binding, and circular dichroism data suggests that the main type of species that interact with DNA is [Zn(NN)]²⁺. Studies varying the % of fetal bovine serum (1-15%) in cell media show that albumin binding decreases the complex activity, indicating that distinct speciation of Zn- and phen-containing species in cell media may affect the cytotoxicity.

Association between dietary intake of some antioxidant micronutrients with some inflammatory and antioxidant markers in active Rheumatoid Arthritis patients

Background: Rheumatoid Arthritis (RA) is an autoimmune disease. Antioxidants intake and body antioxidants status are important in patients with RA. The aim of this study was to investigate the association between dietary intake of some antioxidant micronutrients with some inflammatory and antioxidant markers in patients with active rheumatoid arthritis and comparison with Recommended Dietary Allowance (RDA). Materials and Methods: In this cross-sectional study, eighty-seven patients with active rheumatoid arthritis were included. Dietary antioxidants intake was measured using 24-hour recall questionnaire and food record (3 days). Blood levels of inflammatory and antioxidant markers were determined by laboratory tests. The association between intake of antioxidants with inflammatory and antioxidant markers, and also with RDA were determined using Paired-Samples t-test and Pearson correlation by SPSS software. Results: The findings showed that intakes of vitamin E, zinc, and magnesium in patients were significantly lower and intakes of copper and selenium were significantly higher than RDA (P < 0.05). Significant negative correlations were observed between vitamin A intake with PGE2 [R = -0.31], vitamin C intake with IL-1β [R = -0.25], zinc intake with PGE2 [R = -0.30], IL-2 [R = -0.23], and the activity of glutathione reductase enzyme [R = -0.21], magnesium intake with PGE2 [R = -0.24], IL-1β [R = -0.23] and IL-2 [R = -0.25], and selenium intake with PGE2 [R = -0.21] (P < 0.05). Also, significant positive correlations were observed between intakes of vitamin E and copper with catalase enzyme activity [R = 0.22 and R = 0.21 respectively] (P < 0.05). Conclusion: Some of the antioxidant micronutrients play important roles in the reduction of inflammatory conditions and improve the function of antioxidant enzymes in patients with rheumatoid arthritis.