Showing papers on "Selenium published in 2020"

Mercury: selenium interactions and health implications

Abstract: Measuring the amount of mercury present in the environment or food sources may provide an inadequate reflection of the potential for health risks if the protective effects of selenium are not also considered. Selenium's involvement is apparent throughout the mercury cycle, influencing its transport, biogeochemical exposure, bioavailability, toxicological consequences, and remediation. Likewise, numerous studies indicate that selenium, present in many foods (including fish), protects against mercury exposure. Studies have also shown mercury exposure reduces the activity of selenium dependent enzymes. While seemingly distinct, these concepts may actually be complementary perspectives of the mercury-selenium binding interaction. Owing to the extremely high affinity between mercury and selenium, selenium sequesters mercury and reduces its biological availability. It is obvious that the converse is also true; as a result of the high affinity complexes formed, mercury sequesters selenium. This is important because selenium is required for normal activity of numerous selenium dependent enzymes. Through diversion of selenium into formation of insoluble mercury-selenides, mercury may inhibit the formation of selenium dependent enzymes while supplemental selenium supports their continued synthesis. Further research into mercury-selenium interactions will help us understand the consequences of mercury exposure and identify populations which may be protected or at greater risk to mercury’s toxic effects.

The Role of Selenium in Arsenic and Cadmium Toxicity: an Updated Review of Scientific Literature

Abstract: Arsenic (As) and cadmium (Cd) are elements arousing major public health concerns associated with environmental pollution, high toxicity potential, and carcinogenic nature. However, selenium (Se) at low doses and incorporated into enzymes and proteins has antioxidant properties and protects animals and humans from the risk of various diseases. It also has an exceptionally narrow range between necessary and toxic concentrations, which is a well-known hindrance in its use as a dietary supplement. The present article aims to update and expand the role of Se in As and Cd toxicity discussed in our earlier paper. In general, recent reports show that Se, regardless of its form (as selenite, selenomethionine, nanoSe, or Se from lentils), can reduce As- or Cd-mediated toxicity in the liver, kidney, spleen, brain, or heart in animal models and in cell culture studies. As was suggested in our earlier review, Se antagonizes the toxicity of As and Cd mainly through sequestration of these elements into biologically inert complexes and/or through the action of Se-dependent antioxidant enzymes. An increase in the As methylation efficiency is proposed as a possible mechanism by which Se can reduce As toxicity. However, new studies indicate that Se may also diminish As or Cd toxicity by activation of the Nrf2 pathway. In addition, this paper discusses possible signs of Se toxic effects, which may be a challenge for its future use in the therapy of As and Cd poisoning and provide future directions to address this issue.

Selenium in thyroid disorders — essential knowledge for clinicians

Abstract: In the 1990s, selenium was identified as a component of an enzyme that activates thyroid hormone; since this discovery, the relevance of selenium to thyroid health has been widely studied. Selenium, known primarily for the antioxidant properties of selenoenzymes, is obtained mainly from meat, seafood and grains. Intake levels vary across the world owing largely to differences in soil content and factors affecting its bioavailability to plants. Adverse health effects have been observed at both extremes of intake, with a narrow optimum range. Epidemiological studies have linked an increased risk of autoimmune thyroiditis, Graves disease and goitre to low selenium status. Trials of selenium supplementation in patients with chronic autoimmune thyroiditis have generally resulted in reduced thyroid autoantibody titre without apparent improvements in the clinical course of the disease. In Graves disease, selenium supplementation might lead to faster remission of hyperthyroidism and improved quality of life and eye involvement in patients with mild thyroid eye disease. Despite recommendations only extending to patients with Graves ophthalmopathy, selenium supplementation is widely used by clinicians for other thyroid phenotypes. Ongoing and future trials might help identify individuals who can benefit from selenium supplementation, based, for instance, on individual selenium status or genetic profile.

Selenium and selenoproteins in viral infection with potential relevance to COVID-19.

Abstract: Selenium is a trace element essential to human health largely because of its incorporation into selenoproteins that have a wide range of protective functions. Selenium has an ongoing history of reducing the incidence and severity of various viral infections; for example, a German study found selenium status to be significantly higher in serum samples from surviving than non-surviving COVID-19 patients. Furthermore, a significant, positive, linear association was found between the cure rate of Chinese patients with COVID-19 and regional selenium status. Moreover, the cure rate continued to rise beyond the selenium intake required to optimise selenoproteins, suggesting that selenoproteins are probably not the whole story. Nonetheless, the significantly reduced expression of a number of selenoproteins, including those involved in controlling ER stress, along with increased expression of IL-6 in SARS-CoV-2 infected cells in culture suggests a potential link between reduced selenoprotein expression and COVID-19-associated inflammation. In this comprehensive review, we describe the history of selenium in viral infections and then go on to assess the potential benefits of adequate and even supra-nutritional selenium status. We discuss the indispensable function of the selenoproteins in coordinating a successful immune response and follow by reviewing cytokine excess, a key mediator of morbidity and mortality in COVID-19, and its relationship to selenium status. We comment on the fact that the synthetic redox-active selenium compound, ebselen, has been found experimentally to be a strong inhibitor of the main SARS-CoV-2 protease that enables viral maturation within the host. That finding suggests that redox-active selenium species formed at high selenium intake might hypothetically inhibit SARS-CoV-2 proteases. We consider the tactics that SARS-CoV-2 could employ to evade an adequate host response by interfering with the human selenoprotein system. Recognition of the myriad mechanisms by which selenium might potentially benefit COVID-19 patients provides a rationale for randomised, controlled trials of selenium supplementation in SARS-CoV-2 infection.

Selenium Anticancer Properties and Impact on Cellular Redox Status

Abstract: (1) Background: In this review, we provide information published in recent years on the chemical forms, main biological functions and especially on antioxidant and prooxidant activities of selenium. The main focus is put on the impact of selenoproteins on maintaining cellular redox balance and anticancerogenic function. Moreover, we summarize data on chemotherapeutic application of redox active selenium compounds. (2) Methods: In the first section, main aspects of metabolism and redox activity of selenium compounds is reviewed. The second outlines multiple biological functions, asserted when selenium is incorporated into the structure of selenoproteins. The final section focuses on anticancer activity of selenium and chemotherapeutic application of redox active selenium compounds as well. (3) Results: optimal dietary level of selenium ensures its proper antioxidant and anticancer activity. We pay special attention to antioxidant activities of selenium compounds, especially selenoproteins, and their importance in antioxidant defence. It is worth noting, that data on selenium anticancer properties is still contraversive. Moreover, selenium compounds as chemotherapeutic agents usually are used at supranutritional doses. (4) Conclusions: Selenium play a vital role for many organism systems due to its incorporation into selenoproteins structure. Selenium possesses antioxidant activity at optimal doses, while at supranutritional doses, it displays prooxidant activity. Redox active selenium compounds can be used for cancer treatment; recently special attention is put to selenium containing nanoparticles.

Physical characterization and antibacterial activity of PVA/Chitosan matrix doped by selenium nanoparticles prepared via one-pot laser ablation route

Abstract: Blend of Polyvinyl Alcohol/Chitosan doped by selenium nanoparticles was synthesized via one step laser ablation route to improve the antibacterial activity of the pure blend. The effect of two concentrations of selenium on the optical, structural, and morphological properties of the synthesized PVA/Chitosan/SeNPs nanocomposite films were characterized. The antibacterial activity of the prepared samples has been investigated. XRD and FTIR-ATR results confirm the interaction between selenium nanoparticles and PVA/Chitosan. Furthermore, the change in the values of optical energy band gap confirms the scattered selenium nanoparticles into PVA/Chitosan film. The activity index shows an increase in the diameter zone with increasing the concentration of selenium nanoparticles content. The results confirmed that doping of selenium nanoparticles to (PVA/Chitosan) lead to increase the antibacterial activity of the pure PVA/Chitosan blend that suggests this nanocomposite could be used in several antimicrobial applications.

Selenium detoxification is required for cancer-cell survival.

Abstract: The micronutrient selenium is incorporated via the selenocysteine biosynthesis pathway into the rare amino acid selenocysteine, which is required in selenoproteins such as glutathione peroxidases and thioredoxin reductases1,2. Here, we show that selenophosphate synthetase 2 (SEPHS2), an enzyme in the selenocysteine biosynthesis pathway, is essential for survival of cancer, but not normal, cells. SEPHS2 is required in cancer cells to detoxify selenide, an intermediate that is formed during selenocysteine biosynthesis. Breast and other cancer cells are selenophilic, owing to a secondary function of the cystine/glutamate antiporter SLC7A11 that promotes selenium uptake and selenocysteine biosynthesis, which, by allowing production of selenoproteins such as GPX4, protects cells against ferroptosis. However, this activity also becomes a liability for cancer cells because selenide is poisonous and must be processed by SEPHS2. Accordingly, we find that SEPHS2 protein levels are elevated in samples from people with breast cancer, and that loss of SEPHS2 impairs growth of orthotopic mammary-tumour xenografts in mice. Collectively, our results identify a vulnerability of cancer cells and define the role of selenium metabolism in cancer.

Selenium and outcome in heart failure.

Abstract: AIMS: Severe deficiency of the essential trace element selenium can cause myocardial dysfunction although the mechanism at cellular level is uncertain. Whether, in clinical practice, moderate selenium deficiency is associated with worse symptoms and outcome in patients with heart failure is unknown. METHODS AND RESULTS: BIOSTAT-CHF is a multinational, prospective, observational cohort study that enrolled patients with worsening heart failure. Serum concentrations of selenium were measured by inductively coupled plasma mass spectrometry. Primary endpoint was a composite of all-cause mortality and hospitalization for heart failure; secondary endpoint was all-cause mortality. To investigate potential mechanisms by which selenium deficiency might affect prognosis, human cardiomyocytes were cultured in absence of selenium, and mitochondrial function and oxidative stress were assessed. Serum selenium concentration (deficiency) was <70 μg/L in 485 (20.4%) patients, who were older, more often women, had worse New York Heart Association class, more severe signs and symptoms of heart failure and poorer exercise capacity (6-min walking test) and quality of life (Kansas City Cardiomyopathy Questionnaire). Selenium deficiency was associated with higher rates of the primary endpoint [hazard ratio (HR) 1.23; 95% confidence interval (CI) 1.06-1.42] and all-cause mortality (HR 1.52; 95% CI 1.26-1.86). In cultured human cardiomyocytes, selenium deprivation impaired mitochondrial function and oxidative phosphorylation, and increased intracellular reactive oxygen species levels. CONCLUSIONS: Selenium deficiency in heart failure patients is independently associated with impaired exercise tolerance and a 50% higher mortality rate, and impaired mitochondrial function in vitro, in human cardiomyocytes. Clinical trials are needed to investigate the effect of selenium supplements in patients with heart failure, especially if they have low plasma concentrations of selenium.

The role of selenium metabolism and selenoproteins in cartilage homeostasis and arthropathies.

Abstract: As an essential nutrient and trace element, selenium is required for living organisms and its beneficial roles in human health have been well recognized. The role of selenium is mainly played through selenoproteins synthesized by the selenium metabolic system. Selenoproteins have a wide range of cellular functions including regulation of selenium transport, thyroid hormones, immunity, and redox homeostasis. Selenium deficiency contributes to various diseases, such as cardiovascular disease, cancer, liver disease, and arthropathy—Kashin–Beck disease (KBD) and osteoarthritis (OA). A skeletal developmental disorder, KBD has been reported in low-selenium areas of China, North Korea, and the Siberian region of Russia, and can be alleviated by selenium supplementation. OA, the most common form of arthritis, is a degenerative disease caused by an imbalance in matrix metabolism and is characterized by cartilage destruction. Oxidative stress serves as a major cause of the initiation of OA pathogenesis. Selenium deficiency and dysregulation of selenoproteins are associated with impairments to redox homeostasis in cartilage. We review the recently explored roles of selenium metabolism and selenoproteins in cartilage with an emphasis on two arthropathies, KBD and OA. Moreover, we discuss the potential of therapeutic strategies targeting the biological functions of selenium and selenoproteins for OA treatment. Selenium, a micronutrient found in brazil nuts, shiitake mushrooms, and most meats, may aid in treating joint diseases, including the most common form of arthritis, osteoarthritis (OA). In addition to thyroid hormone metabolism and immunity, selenium is important in antioxidant defense. Oxidative damage can destroy cartilage and harm joints, and selenium deficiency is implicated in several joint diseases. Jin-Hong Kim at Seoul National University in South Korea and co-workers reviewed selenium metabolism, focusing on OA and and Kashin–Beck disease, a skeletal development disorder prevalent in selenium-deficient areas of northeast Asia. They report that selenium-containing proteins protect cells against oxidative damage and that selenium is crucial to cartilage production. Further investigation of selenium metabolism may point the way to new treatments for OA and other joint diseases.

Impact of Selenium Deficiency on Inflammation, Oxidative Stress, and Phagocytosis in Mouse Macrophages.

Abstract: Although it has been reported that selenium (Se) deficiency can trigger inflammation, however, there are few reports on the effect of Se on the function of mouse peritoneal macrophages. Herein, we examined the expression of inflammatory factors, oxidative stress levels, and phagocytosis for primary-cultured peritoneal macrophages using control and Se-deficient groups. Our results revealed that Se deficiency induced the accumulation of oxygen free radicals and weakened antioxidant capacity. Se deficiency also significantly increased the expression of inflammation factors including iNOS, IL-1β, IL-12, IL-10, PTGe, and NF-κB. Meanwhile, Se suppression restrained macrophage production of TNF-α. The results of the phagocytosis assay demonstrated that Se deficiency inhibited the phagocytosis of macrophages. In conclusion, Se-deficient macrophages undergo severe inflammation through the NF-κB pathway due to the accumulation of oxygen free radicals and are hindered in their phagocytic capacity.

Investigating the Antimicrobial Activities of the Biosynthesized Selenium Nanoparticles and Its Statistical Analysis

Abstract: The present investigation concentrates on the green combination of biosynthesized selenium nanoparticles utilizing aqueous extract of cow urine as a green technique with no external chemicals, reagents, or surfactants. The combination of parameters, for example, the sodium selenite precursor concentration, or the concentration of cow urine extract, time of synthesis, and pH on the particle size of combined selenium particles, was explored and enhanced. The participation of the factors in controlling the particle size of reduced SeNPs was quantitatively evaluated by means of analysis of variance (ANOVA). The UV-Vis spectroscopy was utilized to screen the selenium nanoparticle development followed by electron microscopy (SEM and TEM), DLS, AFM, and EDAX. The optimized nanoparticles were subjected to antibacterial activity against Gram-positive and Gram-negative cultures, out of which the highest activity was observed for Klebsiella sp. The biosynthesized and optimized selenium nanoparticles can be further used for various pharmaceutical or industrial applications.

Foliar applications of bio-fabricated selenium nanoparticles to improve the growth of wheat plants under drought stress

Abstract: Abstract The present study was aimed to biosynthesize selenium nanoparticles (SeNPs) and assess their foliar applications to improve the growth of wheat plants under controlled irrigation and drought stress. Bud aqueous extract of Allium sativum L. was used as a reducing and stabilizing agent of SeNPs followed by their optical and morphological characterization by using ultraviolet-visible spectroscopy, scanning electron microscopy, Fourier-transform infrared, and energy dispersive X-ray analysis. Various concentrations of SeNPs (10, 20, 30, and 40 mg/L) were applied exogenously to drought-tolerant (V1) and drought-susceptible (V2) wheat varieties at the trifoliate stage. Under the positive control conditions, plants were irrigated with 450 mL of water/pot (100% field capacity); and under water-deficit environment, plants were irrigated with 160 mL of water/pot (35% field capacity). Remarkable increase in plant height, shoot length, shoot fresh weight, shoot dry weight, root length, root fresh weight, root dry weight, leaf area, leaf number, and leaf length has been observed when 30 mg/L concentration of SeNPs was used. However, the plant morphological parameters decreased gradually at higher concentrations (40 mg/L) in both selected wheat varieties. Therefore, 30 mg/L concentration of SeNPs was found most preferable to enhance the growth of selected wheat varieties under normal and water-deficient conditions.

Biotransformation of Selenium by Lactic Acid Bacteria: Formation of Seleno-Nanoparticles and Seleno-Amino Acids.

Abstract: Selenium (Se) is an essential micronutrient for the majority of living organisms, and it has been identified as selenocysteine in the active site of several selenoproteins such as glutathione peroxidase, thioredoxin reductase, and deiodinases. Se deficiency in humans is associated with viral infections, thyroid dysfunction, different types of cancer, and aging. In several European countries as well as in Argentina, Se intake is below the recommended dietary Intake (RDI). Some lactic acid bacteria (LAB) can accumulate and bio-transform selenite (toxic) into Se-nanoparticles (SeNPs) and Se-amino acids (non-toxic). The microbial growth, Se metabolite distribution, and the glutathione reductase (involved in selenite reduction) activity of Se-enriched LAB were studied in this work. The ninety-six assayed strains, belonging to the genera Lactococcus, Weissella, Leuconostoc, Lactobacillus, Enterococcus, and Fructobacillus could grow in the presence of 5 ppm sodium selenite. From the total, eight strains could remove more than 80% of the added Se from the culture medium. These bacteria accumulated intracellularly between 1.2 and 2.5 ppm of the added Se, from which F. tropaeoli CRL 2034 contained the highest intracellular amount. These strains produced only the seleno-amino acid SeCys as observed by LC-ICP-MS and confirmed by LC-ESI-MS/MS. The intracellular SeCys concentrations were between 0.015 and 0.880 ppm; Lb. brevis CRL 2051 (0.873 ppm), Lb. plantarum CRL 2030 (0.867 ppm), and F. tropaeoli CRL 2034 (0.625 ppm) were the strains that showed the highest concentrations. Glutathione reductase activity values were higher when the strains were grown in the presence of Se except for the F. tropaeoli CRL 2034 strain, which showed an opposite behavior. The cellular morphology of the strains was not affected by the presence of Se in the culture medium; interestingly, all the strains were able to form spherical SeNPs as determined by transmission electron microscopy (TEM). Only two Enterococcus strains produced the volatile Se compounds dimethyl-diselenide identified by GC-MS. Our results show that Lb. brevis CRL 2051, Lb. plantarum CRL 2030, and F. tropaeoli CRL 2034 could be used for the development of nutraceuticals or as starter cultures for the bio-enrichment of fermented fruit beverages with SeCys and SeNPs.

ICP-MS trace element analysis in serum and whole blood.

Abstract: Trace elements and minerals are compounds that are essential for the support of a variety of biological functions and play an important role in the formation of and the defense against oxidative stress. Here we describe a technique, allowing sequential detection of the trace elements (K, Zn, Se, Cu, Mn, Fe, Mg) in serum and whole blood by an ICP-MS method using single work-up, which is a simple, quick and robust method for the sequential measurement and quantification of the trace elements Sodium (Na), Potassium (K), Calcium (Ca), Zinc (Zn), Selenium (Se), Copper (Cu), Iron (Fe), Manganese (Mn) and Magnesium (Mg) in whole blood as well as Copper (Cu), Selenium (Se), Zinc (Zn), Iron (Fe), Magnesium (Mg), Manganese (Mn), Chromium (Cr), Nickel (Ni), Gold (Au) and Lithium (Li) in human serum. For analysis, only 100 μl of serum or whole blood is sufficient, which make this method suitable for detecting trace element deficiency or excess in newborns and infants. All samples were processed and analyzed by ICP-MS (Agilent Technologies). The accuracy, precision, linearity and the limit of quantification (LOQ), Limit of Blank (LOB) and the limit of detection (LOD) of the method were assessed. Recovery rates were between 80-130% for most of the analyzed elements; repeatabilities (Cv %) calculated were below 15% for most of the measured elements. The validity of the proposed methodology was assessed by analyzing a certified human serum and whole blood material with known concentrations for all elements; the method described is ready for routine use in biomonitoring studies.

Solid-state fermentation for enhanced production of selenium nanoparticles by gamma-irradiated Monascus purpureus and their biological evaluation and photocatalytic activities

Abstract: Selenium nanoparticles (SeNPs) were successfully synthesized using the culture extract of Monascus purpureus ATCC16436 grown on sugarcane bagasse under solid-state fermentation. The rapid synthesis of SeNPs was completed after 30 min as confirmed by UV–Vis spectroscopy. Functional groups present in the synthesized SeNPs samples were confirmed by Fourier transform infrared spectroscopy. The synthesized SeNPs showed a single-phase crystalline structure. Transmission electron microscope revealed the spherical shape and the mean particle size was 46.58 nm. Dynamic light scattering analysis showed that the synthesized SeNPs were monodispersed and the recorded polydispersity index value was 0.205. Zeta potential value of − 24.01 mV indicated the high stability of SeNPs. Besides, the biological activities of antioxidant, anticancer and antimicrobial as well as the photocatalytic activities were also studied. SeNPs showed promising antioxidant activity with 50% inhibitory concentration of 85.92 µg mL−1. Based on the MTT assay, SeNPs inhibited the proliferation of normal human melanocytes, human breast and liver cancer cell lines with 50% inhibitory concentrations of 45.21, 61.86 and 200.15 µg mL−1, respectively. SeNPs showed broad spectrum of antimicrobial potential against the tested human and plant pathogens. SeNPs showed efficient degradation of methylene blue dye. Moreover, the effect of gamma irradiation on the production enhancement of SeNPs was also adopted. Exposure of the fungal spores to gamma rays at 1000 Gy increased the yield of SeNPs to approximately fivefold. Hence, this study suggests a new and alternate approach with the excellent biotechnological potentiality for the production of SeNPs.

Nanobiotechnology approach in intracellular selenium nanoparticle synthesis using Saccharomyces cerevisiae-fabrication and characterization.

Abstract: Selenium nanoparticles (Se NPs) were synthesized using Saccharomyces cerevisiae yeast. Influences of different amounts of sodium selenite (5.0, 10.0, 15.0, 20.0, and 25 µg) were evaluated on growth of yeast during incubation at 32 °C, during 4 days. UV–Vis spectroscopy results have shown that synthesized Se NPs had broad emission peak (λmax) in the wavelength around 350 nm which demonstrated that formation of Se NPs occurred in intracellular manner. Physico-chemical characteristics of the synthesized Se NPs using dynamic light scattering particle-size analyzer indicated that the fabricated Se NPs had particle size, polydispersity index, and zeta potential ranging from 75 to 709 nm, 0.189 to 0989, and −7.06 to −10.3 mV, respectively. Obtained results revealed that intracellular Se NPs with minimum particle size (75 nm), maximum zeta potential (−10.3 mV), and antioxidant activity (48.5%) were synthesized using minimum amount of selenium salt (5 µg). However, most uniform Se NPs were formed using maximum amount of selenium salt (25 µg). Results also indicated that by increasing amount of sodium selenite in the culture media, from 5.0 to 25 µg, antioxidant activity of the formed Se NPs decreased from 48.5 to 20.8, respectively.

Nanoparticles of selenium as high bioavailable and non-toxic supplement alternatives for broiler chickens.

Abstract: Selenium is commonly used in the poultry industry as an additive in broiler feed to improve immunity and overall health. The selenium comes in different forms, inorganic and organic selenium, as sodium selenite and selenomethionine, respectively. This study proposes the use of nanoparticles of selenium (nanoSe) for improved delivery and absorption of the trace element while causing no toxicity. Previous studies have shown the success in utilizing nanoSe in broiler feed, with increased absorption and diffusion of material into organs and tissues, and increased antioxidant capacity. However, the mechanism of nanoSe conversion remains unknown, and the gut microbiota is believed to play a significant role in the process. The use of inorganic selenium in poultry feed demonstrated a lower bioavailability in breast (P ≤ 0.01) and duodenum tissue (P ≤ 0.05), and increased accumulation in organs involved in detoxification processes as compared to organic selenium and selenium nanoparticle supplementation. Histopathological analysis showed that nanoSe did not cause any damaging effects to the tissues analysed, revealing intact epithelial cells in the digestive system and neuronal bodies in brain tissue. The results indicate that nanoparticles of selenium operate a similar way to organic selenium and could potentially be used in poultry feed as a trace element additive.