N,N'bis-(2-mercaptoethyl) isophthalamide (NBMI) exerts neuroprotection against lead-induced toxicity in U-87 MG cells

Should ebselen be considered for the treatment of mercury intoxication? A minireview

Mercury is a ubiquitous environmental contaminant and can be found in inorganic (Hg0, Hg+ and Hg2+) and organic forms (chiefly CH3Hg+ or MeHg+). The main route of human, mammals and bird exposure occurs via predatory fish ingestion. Occupational exposure to Hg0 (and Hg2+) can also occur; furthermore, in gold mining areas the exposure to inorganic Hg can also be high. The toxicity of electrophilic forms of Hg (E+Hg) is mediated by disruption of thiol (-SH)- or selenol (-SeH)-containing proteins. The therapeutic approaches to treat methylmercury (MeHg+), Hg0 and Hg2+ are limited. Here we discuss the potential use of ebselen as a potential therapeutic agent to lower the body burden of Hg in man. Ebselen is a safe drug for humans and has been tested in clinical trials (for instance, brain ischemia, noise-induce hearing loss, diabetes complications, bipolar disorders) at doses varying from 400 to 3600 mg per day. Two clinical trials with ebselen in moderate and severe COVID are also approved. Ebselen can be metabolized to an intermediate with -SeH (selenol) functional group, which has a greater affinity to electrophilic Hg (E+Hg) forms than the available thiol-containing therapeutic agents. Accordingly, as observed in vitro and rodent models in vivo, Ebselen exhibited protective effects against MeHg+, indicating its potential as a therapeutic agent to treat MeHg+ overexposure. The combined use of ebselen with thiol-containing molecules (e.g. N-acetylcysteine and enaramide)) is also commented, because they can have synergistic protective effects against MeHg+.

An Unusual Cause of Complete Heart Block

Mercury poisoning is most frequently associated with multiorgan toxicity involving the brain, lungs, and kidneys. Cardiotoxic effects of mercury are rare and often overlooked. We demonstrate mercury poisoning-induced cardiotoxicity through a case study and then provide a review of the incidence, pathophysiology, and associated management plans. This case illustrates the importance of thorough history-taking to promote early recognition of toxicity.

Naringin administration mitigates oxidative stress, anemia, and hypertension in lead acetate-induced cardio-renal dysfunction in cockerel chicks

Lead is one of the major pollutants that is harmful to both animals and humans. It is found in every aspect of the environment such as the air, water, and soil. This pollutant affects both wild and domestic birds. Naringin has an active principle called flavonoid that has been found to have medicinal properties, mostly because of its antioxidant and metal chelating properties. This study was carried out to investigate the protective effect of naringin as an antioxidant against lead-induced anemia, cardio and nephrotoxicity, and hypertension. This study also aimed at elucidating the use of naringin as a heavy metal binder in poultry feed. Thirty-six cockerel chicks were used for this study, and randomly grouped into six groups per group; group A served as the control, group B received Pb-only (300 ppm), group C (Pb and naringin; 80 mg/kg), group D (Pb and naringin; 160 mg/kg), group E (naringin 80 mg/kg), and group F (naringin 160 mg/kg), respectively, for 8 weeks. Lead (Pb) was administered via drinking water, while naringin was administered via oral gavage. Lead acetate intoxication precipitated anemia as indicated by significant reductions in the values of PCV, RBC, and Hb concentration in lead-treated chicks when compared with the controls. Also, lead administration induced hypertension together with increased oxidative stress, depletion of the antioxidant defense system, reduced nitric oxide production, and an increase in high blood pressure. Immunohistochemistry indicated high expressions of cardiac troponin, renal angiotensin-converting enzymes, and renal neutrophil gelatinase-associated lipocalin. Treatment with naringin corrected anemia, reduced oxidative stress, improved antioxidant system, reduced high blood pressure, and offered protection against lead acetate-induced cardio-renal dysfunction in cockerel chicks. We recommend that naringin should be incorporated poultry feeds as a metal binder.

Reversal of genetic brain iron accumulation by N,N'-bis(2-mercaptoethyl)isophthalamide, a lipophilic metal chelator, in mice

N,N'-bis(2-mercaptoethyl)isophthalamide (NBMI) is a novel lipophilic metal chelator and antioxidant used in mercury poisoning. Recent studies have suggested that NBMI may also bind to other metals such as lead and iron. Since NBMI can enter the brain, we evaluated if NBMI removes excess iron from the iron-loaded brain and ameliorates iron-induced oxidative stress. First, NBMI exhibited preferential binding to ferrous (Fe²⁺) iron with a negligible binding affinity to ferric (Fe³⁺) iron, indicating a selective chelation of labile iron. Second, NBMI protected SH-SY5Y human neuroblastoma cells from the cytotoxic effects of high iron. NBMI also decreased cellular labile iron and lessened the production of iron-induced reactive oxygen species in these cells. Deferiprone (DFP), a commonly used oral iron chelator, failed to prevent iron-induced cytotoxicity or labile iron accumulation. Next, we validated the efficacy of NBMI in Hfe H67D mutant mice, a mouse model of brain iron accumulation (BIA). Oral gavage of NBMI for 6 weeks decreased iron accumulation in the brain as well as liver, whereas DFP showed iron chelation only in the liver, but not in the brain. Notably, depletion of brain copper and anemia were observed in BIA mice treated with DFP, but not with NBMI, suggesting a superior safety profile of NBMI over DFP for long-term use. Collectively, our study demonstrates that NBMI provides a neuroprotective effect against BIA and has therapeutic potential for neurodegenerative diseases associated with BIA.