Investigation of the cytotoxicity, genotoxicity and antioxidant prospects of JM-20 on human blood cells: A multi-target compound with potential therapeutic applications.

JM-20 is a 1,5-benzodiazepine compound fused to a dihydropyridine fraction with different pharmacological properties. However, its potential toxic effects on blood cells have not yet been reported. Thus, the present study aimed to investigate, for the first time, the possible cytotoxicity of JM-20 through cell viability, cell cycle, morphology changes, reactive species (RS) to DCFH-DA, and lipid peroxidation in human leukocytes, its hemolytic effect on human erythrocytes, and its potential DNA genotoxicity using plasmid DNA in vitro. Furthermore, the compound's ability to reduce the DPPH radical was also measured. Human blood was obtained from healthy volunteers (30 ± 10 years old), and the leukocytes or erythrocytes were immediately isolated and treated with different concentrations of JM-20. A cytoprotective effect was exhibited by 10 µM JM-20 against 1 mM tert-butyl hydroperoxide (t-but-OOH) in the leukocytes. However, the highest tested concentrations of the compound (20 and 50 µM) changed the morphology and caused a significant decrease in the cell viability of leukocytes (p < 0.05, in comparison with Control). All tested concentrations of JM-20 also resulted in a significant increase in intracellular RS as measured by DCFH-DA in these cells (p < 0.05, in comparison with Control). On the other hand, the results point out a potent antioxidant effect of JM-20, which was similar to the classical antioxidant α-tocopherol. The IC50 value of JM-20 against the lipid peroxidation induced by (FeII) was 1.051 µM ± 0.21, while the IC50 value of α-tocopherol in this parameter was 1.065 µM ± 0.34. Additionally, 50 and 100 µM JM-20 reduced the DPPH radical in a statistically similar way to the 100 µM α-tocopherol (p < 0.05, in comparison with the control). No significant hemolysis in erythrocytes, no cell cycle changes in leukocytes, and no genotoxic effects in plasmid DNA were induced by JM-20 at any tested concentration. The in silico pharmacokinetic and toxicological properties of JM-20, derivatives, and nifedipine were also studied. Here, our findings demonstrate that JM-20 and its putative metabolites exhibit similar characteristics to nifedipine, and the in vitro and in silico data support the low toxicity of JM-20 to mammals.

Methylglyoxal disturbs DNA repair and glyoxalase I system in Saccharomyces cerevisiae.

Methylglyoxal (MG) is a highly reactive aldehyde able to form covalent adducts with proteins and nucleic acids, disrupting cellular functions. In this study, we performed a screening of Saccharomyces cerevisiae (S. cerevisiae) strains to find out which genes of cells are responsive to MG, emphasizing genes against oxidative stress and DNA repair. Yeast strains were grown in the YPD-Galactose medium containing MG (0.5 to 12 mM). The tolerance to MG was evaluated by determining cellular growth and cell viability. The toxicity of MG was more pronounced in the strains with deletion in genes engaged with DNA repair checkpoint proteins, namely Rad23 and Rad50. MG also impaired the growth and viability of S. cerevisiae mutant strains Glo1 and Gsh1, both components of the glyoxalase I system. Differently, the strains with deletion in genes encoding for antioxidant enzymes were apparently resistant to MG. In summary, our data indicate that DNA repair and MG detoxification pathways are keys in the control of MG toxicity in S. cerevisiae.

Evaluation of methylglyoxal toxicity in human erythrocytes, leukocytes and platelets.

Methylglyoxal (MG) is a reactive dicarbonyl metabolite originated mainly from glucose degradation pathway that plays an important role in the pathogenesis of diabetes mellitus (DM). Reactions of MG with biological macromolecules (proteins, DNA and lipids) can induce cytotoxicity and apoptosis. Here, human erythrocytes, leukocytes and platelets were acutely exposed to MG at concentration ranging from 0.025 to 10 mM. Afterwards, hemolysis and osmotic fragility in erythrocytes, DNA damage and cell viability in leukocytes, and the activity of purinergic ecto-nucleotidases in platelets were evaluated. The levels of glycated products from leukocytes and free amino groups from erythrocytes and platelets were also measured. MG caused fragility of membrane, hemolysis and depletion of amino groups in erythrocytes. DNA damage, loss of cell viability and increased levels of glycated products were observed in leukocytes. In platelets, MG inhibited the activity of enzymes NTPDase, 5'-nucleotidase and adenosine deaminase (ADA) without affecting the levels of free amino groups. Our findings provide insights for understanding the mechanisms involved in MG acute toxicity towards distinct blood cells.

JM-20 potently prevents the onset of caffeine-induced anxiogenic phenotypes in zebrafish (Danio rerio).

Anxiety is among the most prevalent mental disorders present in the general population. Benzodiazepines are the most commonly prescribed drugs for the treatment of anxiety. Using zebrafish as a model organism, we investigated the anxiolytic activity of JM-20, a novel hybrid molecule with a 1,5-benzodiazepine ring fused to a dihydropyridine moiety. Firstly, we carried out some assays to analyze the possible toxicity mediated by JM-20. For this, zebrafish were exposed to different JM-20 concentrations (0-5 µM) for 96 h. Then, using the novel tank test, we evaluated both locomotor and anxiety-like behavior of the animals. Furthermore, brain, liver and plasma were removed to assess toxicity parameters. JM-20 exposure did not cause changes on novel tank, and also did not alter brain viability, hepatic LDH and plasma ALT levels. Afterward, we investigated whether a pre-exposure to JM-20 would prevent the anxiogenic effect evoked by caffeine. In the novel tank test, caffeine significantly decreased the time spent at the top, as well as the number of transitions to the top area. Moreover, caffeine decreased both the total and average time spent in the lit area, as well as increased the number of risk episodes evaluated by the light-dark test. Whole-body cortisol levels were also increased by caffeine exposure. Interestingly, pre-treatment with JM-20 abolished all alterations induced by caffeine. The anxiolytic effect profile of JM-20 was similar to those found for diazepam (positive control). Our findings show, for the first time, the anxiolytic effect of JM-20 in zebrafish, and its relationship with cortisol regulation.

Effects of diphenyl diselenide and diphenyl ditellurite on chicken embryo development.

Studies of our group has demonstrated that (PhSe)2 plays some pharmacologic activities. In addition, it is possible that this compound would be an alternative source of organic selenium in animal foods. However, previous works showed that diphenyl diselenide (PhSe)2 and diphenyl ditelluride (PhTe)2 are toxic for mammals, but their undesirable effects were never tested in avian models. Then, the present study was carried to examine the possible teratogenic effects of (PhSe)2 and (PhTe)2 on chicken embryo development. The eggs were injected with (PhSe)2 at 0, 1 and 10 nmol or with (PhTe)2 at 4 nmol. The control was injected with 10 µl of soya bean oil (vehicle). In order to determine the possible toxic effect of these chemicals, we measure the embryo dimensions, the encephalon, heart and liver weight, thiobarturic acid reactive species (TBARS) level and the δ-aminonevulinate dehydratase (ALA-D) activity. (PhSe)2 and (PhTe)2 did not affect the embryo dimensions. Treatment with (PhSe)2 at 10 nmol per egg caused a increase on TBARS level and on ALA-D activity of the liver tissue, whereas (PhTe)2 decreased encephalon weight, had a tendency to increase to increase TBARS level but did not affect ALA-D activity. Taken together, these results indicate that (PhSe)2 and (PhTe)2 are slightly toxic for chicken embryos. Furthermore, (PhTe)2 caused a decrease in encephalon, which indicates its neurotoxicity. Finally, these results indicate that (PhTe)2 seems not be promissory for therapeutic applications, whereas (PhSe)2 could be of clinical and/or nutritional concern, which will be target for further researches.

Ebselen and Diphenyl Diselenide Inhibit SARS-CoV-2 Replication at Non-Toxic Concentrations to Human Cell Lines.

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was the causative agent of the COVID-19 pandemic, a global public health problem. Despite the numerous studies for drug repurposing, there are only two FDA-approved antiviral agents (Remdesivir and Nirmatrelvir) for non-hospitalized patients with mild-to-moderate COVID-19 symptoms. Consequently, it is pivotal to search for new molecules with anti-SARS-CoV-2 activity and to study their effects in the human immune system. Ebselen (Eb) is an organoselenium compound that is safe for humans and has antioxidant, anti-inflammatory, and antimicrobial properties. Diphenyl diselenide ((PhSe)2) shares several pharmacological properties with Eb and is of low toxicity to mammals. Herein, we investigated Eb and (PhSe)2 anti-SARS-CoV-2 activity in a human pneumocytes cell model (Calu-3) and analyzed their toxic effects on human peripheral blood mononuclear cells (PBMCs). Both compounds significantly inhibited the SARS-CoV-2 replication in Calu-3 cells. The EC50 values for Eb and (PhSe)2 after 24 h post-infection (hpi) were 3.8 µM and 3.9 µM, respectively, and after 48 hpi were 2.6 µM and 3.4 µM. These concentrations are safe for non-infected cells, since the CC50 values found for Eb and (PhSe)2 on Calu-3 were greater than 200 µM. Importantly, the concentration rates tested on viral replication were not toxic to human PBMCs. Therefore, our findings reinforce the efficacy of Eb and demonstrate (PhSe)2 as a new candidate to be tested in future trials against SARS-CoV-2 infection/inflammation conditions.

Diphenyl ditelluride targets brain selenoproteins in vivo: inhibition of cerebral thioredoxin reductase and glutathione peroxidase in mice after acute exposure.

In this study, we investigated the effect of diphenyl ditelluride (PhTe)(2) administration (10 and 50 µmol/kg) on adult mouse behavioral performance as well as several parameters of oxidative stress in the brain and liver. Adult mice were injected with (PhTe)(2) or canola oil subcutaneously (s.c.) daily for 7 days. Results demonstrated that (PhTe)(2) induced prominent signs of toxicity (body weight loss), behavioral alterations and increased in lipid peroxidation in brain. 50 µmol/kg (PhTe)(2) inhibited blood δ-aminolevulinic acid dehydratase (δ-ALA-D), a redox sensitive enzyme. (PhTe)(2) caused an increase in cerebral non-protein thiol (NPSH) and protein thiol (PSH) groups. In the liver, 50 µmol/kg (PhTe)(2) decreased NPSH, but did not alter the content of protein thiol groups. (PhTe)(2) decreased cerebral antioxidant enzymes (catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx), and thioredoxin reductase (TrxR). In liver, (PhTe)(2) increase SOD and GR and decreased GPx activity. Results obtained herein suggest that the brain was more susceptible to oxidative stress induced by (PhTe)(2) than the liver. Furthermore, we have demonstrated for the first time that TrxR is an in vivo target for (PhTe)(2.) Combined, these results highlight a novel molecular mechanism involved in the toxicity of (PhTe)(2). In particular the inhibition of important selenoenzymes (TrxR and GPx) seems to be involved in the neurotoxicity associated with (PhTe)(2) exposure in adult mice.

Methylglyoxal disrupts the functionality of rat liver mitochondria.

Methylglyoxal (MG) is a reactive metabolite derived from different physiological pathways. Its production can be harmful to cells via glycation reactions of lipids, DNA, and proteins. But, the effects of MG on mitochondrial functioning and bioenergetic responses are still elusive. Then, the effects of MG on key parameters of mitochondrial functionality were examined here. Isolated rat liver mitochondria were exposed to 0.1-10 mM of MG to determine its toxicity in the mitochondrial viability, membrane potential (Δψm), swelling and the superoxide (O2•-) production. Besides, mitochondrial oxidative phosphorylation parameters were analyzed by high-resolution respiratory (HRR) assay. In this set of experiments, routine state, PM state (pyruvate/malate), oxidative phosphorylation (OXPHOS), LEAK respiration, electron transport system (ETS) and oxygen residual (ROX) states were evaluated. HRR showed that PM state, OXPHOS CI-Linked, LEAK respiration, ETS CI/CII-Linked and ETS CII-Linked/ROX were significantly inhibited by MG exposure. MG also inhibited the complex II activity, and decreased Δψm and the viability of mitochondria. Taken together, our data indicates that MG is an inductor of mitochondrial dysfunctions and impairs important steps of respiratory chain, effects that can alter bioenergetics responses.