Selenium (Se) has recently been demonstrated to reduce inorganic mercury (IHg) accumulation in rice plants, while its mechanism is far from clear. Here, we aimed at exploring the potential effects of ...Se application routes (soil or foliar application with Se), speciation (selenite and selenate), and doses on IHg-Se antagonistic interactions in soil-rice systems. Results of our pot experiments indicated that soil application but not foliar application could evidently reduce tissue IHg concentrations (root: 0–48%, straw: 15–58%, and brown rice: 26–74%), although both application routes resulted in comparable Se accumulation in aboveground tissues. Meanwhile, IHg distribution in root generally increased with amended Se doses in soil, suggesting antagonistic interactions between IHg and Se in root. These results provided initial evidence that IHg-Se interactions in the rhizosphere (i.e., soil or rice root), instead of those in the aboveground tissues, could probably be more responsible for the reduced IHg bioaccumulation following Se application. Furthermore, Se dose rather than Se speciation was found to be more important in controlling IHg accumulation in rice. Our findings regarding the importance of IHg-Se interactions in the rhizosphere, together with the systematic investigation of key factors affecting IHg-Se antagonism and IHg bioaccumulation, advance our understanding of Hg dynamics in soil-rice systems.
•Soil application with Se could reduce inorganic mercury (IHg) accumulation in rice.•Foliar application with Se could increase Se but not IHg accumulation in rice.•IHg-Se antagonism in soil-rice systems depends on Se doses and Se application routes.•Se speciation (selenite and selenate) may play a minor role in IHg-Se antagonism.•IHg-Se interactions in soil could be important in explaining IHg-Se antagonism.
This research was conducted to evaluate the effects of selenium-enriched probiotics (SP) on growth performance, antioxidant status, immune function, and selenoprotein gene expression of piglets under ...natural high ambient temperature in summer. Forty-eight crossbred weanling piglets randomly allocated to four groups were fed for 42 days ad libitum a basal diet without (Con, 0.16 mg Se/kg) and with supplementation of probiotics (P, 0.16 mg Se/kg), sodium selenite (SS, 0.46 mg Se/kg), and SP (0.46 mg Se/kg). From each group, three piglets were randomly selected for blood collection on days 0, 14, 28, and 42 and tissue collection on day 42. The SP improved growth performance of piglets. Both SS and SP increased blood glutathione peroxidase activity and tissue thioredoxin reductase 1 mRNA expression, with SP being higher than SS. All P, SS, and SP supplementation increased the superoxide dismutase activity (40.1, 53.0, and 64.5%), glutathione content (84.6, 104, and 165%), TCR-induced T lymphocyte proliferation (20.8, 26.4, and 50.0%), and IL-2 concentration (24.9, 27.2, and 46.2%) and decreased malondialdehyde content (25.1, 26.3, and 49.3%), respectively. The greatest effects of SP supplementation suggest that SP may serve as a better feed additive than P or SS for piglets under high-temperature environments.
High selenium status has been linked to elevated blood cholesterol levels in cross-sectional studies.
To investigate the effect of selenium supplementation on plasma lipids.
Randomized, ...placebo-controlled, parallel-group study stratified by age and sex. Participants, research nurses, and persons assessing outcomes were blinded to treatment assignment. (International Standard Randomised Controlled Trial Number Register registration number: ISRCTN25193534)
4 general practices in the United Kingdom.
501 volunteers aged 60 to 74 years.
Participants received selenium, 100 mcg/d (n = 127), 200 mcg/d (n = 127), or 300 mcg/d (n = 126), as high-selenium yeast or a yeast-based placebo (n = 121) for 6 months.
Total and high-density lipoprotein (HDL) cholesterol concentrations were measured in nonfasting plasma samples stored from participants in the UK PRECISE (United Kingdom PREvention of Cancer by Intervention with SElenium) Pilot Study at baseline (n = 454) and at 6 months (n = 394). Non-HDL cholesterol levels were calculated.
Mean plasma selenium concentration was 88.8 ng/g (SD, 19.2) at baseline and increased statistically significantly in the treatment groups. The adjusted difference in change in total cholesterol levels for selenium compared with placebo was -0.22 mmol/L (-8.5 mg/dL) (95% CI, -0.42 to -0.03 mmol/L -16.2 to -1.2 mg/dL; P = 0.02) for 100 mcg of selenium per day, -0.25 mmol/L (-9.7 mg/dL) (CI, -0.44 to -0.07 mmol/L -17.0 to -2.7 mg/dL; P = 0.008) for 200 mcg of selenium per day, and -0.07 mmol/L (-2.7 mg/dL) (CI, -0.26 to 0.12 mmol/L -10.1 to 4.6 mg/dL; P = 0.46) for 300 mcg of selenium per day. Similar reductions were observed for non-HDL cholesterol levels. There was no apparent difference in change in HDL cholesterol levels with 100 and 200 mcg of selenium per day, but the difference was an adjusted 0.06 mmol/L (2.3 mg/dL) (CI, 0.00 to 0.11 mmol/L 0.0 to 4.3 mg/dL; P = 0.045) with 300 mcg of selenium per day. The total-HDL cholesterol ratio decreased progressively with increasing selenium dose (overall P = 0.01).
The duration of supplementation was limited, as was the age range of the participants.
Selenium supplementation seemed to have modestly beneficial effects on plasma lipid levels in this sample of persons with relatively low selenium status. The clinical significance of the findings is unclear and should not be used to justify the use of selenium supplementation as additional or alternative therapy for dyslipidemia. This is particularly true for persons with higher selenium status, given the limitations of the trial and the potential additional risk in other metabolic dimensions.
The Cancer Research Campaign (now Cancer Research UK) and the University of Surrey.
Extensive research is being carried out globally to design and develop new selenium compounds for various biological applications such as antioxidants, radio-protectors, anti-carcinogenic agents, ...biocides, etc. In this pursuit, 3,3′-diselenodipropionic acid (DSePA), a synthetic organoselenium compound, has received considerable attention for its biological activities.
This review intends to give a comprehensive account of research on DSePA so as to facilitate further research activities on this organoselenium compound and to realize its full potential in different areas of biological and pharmacological sciences.
It is an interesting diselenide structurally related to selenocystine. It shows moderate glutathione peroxidase (GPx)-like activity and is an excellent scavenger of reactive oxygen species (ROS). Exposure to radiation, as envisaged during radiation therapy, has been associated with normal tissue side effects and also with the decrease in selenium levels in the body. In vitro and in vivo evaluation of DSePA has confirmed its ability to reduce radiation induced side effects into normal tissues. Administration of DSePA through intraperitoneal (IP) or oral route to mice in a dose range of 2 to 2.5 mg/kg body weight has shown survival advantage against whole body irradiation and a significant protection to lung tissue against thoracic irradiation. Pharmacokinetic profiling of DSePA suggests its maximum absorption in the lung.
Research work on DSePA reported in fifteen years or so indicates that it is a promising multifunctional organoselenium compound exhibiting many important activities of biological relevance apart from radioprotection.
Display omitted
•3,3′-diselenodipropionic acid (DSePA) is a synthetic derivative of selenocystine.•DSePA is highly reactive towards ROS and takes part in GPx-like reactions.•It is relatively safer (higher LD50) as compared to other selenoaminoacids.•It is pharmacologically active agent for radioprotection.•It is used as constituent of redox sensitive drug delivery systems.•It catalyses reduction of S-nitrosothiols to generate NO.
Various human diseases, including different types of cancer, are associated with a disturbed intracellular redox balance and oxidative stress (OS). The past decade has witnessed the emergence of ...redox‐modulating compounds able to utilize such pre‐existing disturbances in the redox state of sick cells for therapeutic advantage. Selenium‐ and tellurium‐based agents turn the oxidizing redox environment present in certain cancer cells into a lethal cocktail of reactive species that push these cells over a critical redox threshold and ultimately kill them through apoptosis. This kind of toxicity is highly selective: normal, healthy cells remain largely unaffected, since changes to their naturally low levels of oxidizing species produce little effect. To further improve selectivity, multifunctional sensor/effector agents are now required that recognize the biochemical signature of OS in target cells. The synthesis of such compounds provides interesting challenges for chemistry in the future.
Programmed destruction: Selenium‐ and tellurium‐based agents turn the oxidizing redox environment present in certain cancer cells into a lethal cocktail of reactive species, which pushes these cells over a critical redox threshold and ultimately kills them through apoptosis (see figure).
Increasing evidences suggest that nanoscale zero-valent iron (nZVI) is an effective agent for treatment and removal of selenium from water. For example, 1.3 mM selenite was quickly removed from water ...within 3 min with 5 g/L nZVI. In this work, reaction mechanisms of selenite Se(IV) in a single core–shell structured nanoscale zero-valent iron (nZVI) particle were studied with the method of spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) integrated with X-ray energy dispersive spectroscopy (XEDS). This method was utilized to visualize solid phase translocation and transformation of Se(IV) such as diffusion, reduction, deposition and the effect of surface defects in a single nanoparticle. Se(IV) was reduced to Se(-II) and Se(0), which then formed a 0.5 nm layer of selenium at the iron oxide-Fe(0) interface at a depth of 6 nm from the surface. The results provided near atomic-resolution proof on the intraparticle diffusion-reduction of Se(IV) induced by nZVI. The STEM mapping also discovered that defects on the surface layer accelerate the diffusion of selenium and increase the capacity of nZVI for selenium sequestration.
Mechanisms of selenium (IV) sequestration in nanoscale zero-valent iron (nZVI). Display omitted
•Se(IV) can be separated from water, reduced and encapsulated by nZVI.•Near atomic-resolution imaging on the Se diffusion-reduction in nZVI is obtained.•Defects on the nZVI nanoparticles apparently can enhance selenium removal.•Reduction and sequestration fully explain rapid and large capacity Se(IV) removal.•STEM-XEDS is usable for visualizing solid phase reaction at near atomic resolution.
Background and aims
Ageing is an important factor for controlling selenium bioavailability and toxicity in soil.
Methods
The ageing processes of selenite and selenate in two soils were systematically ...investigated by adopting diffusive gradients in thin film technique (DGT) and sequential extraction.
Results
Soluble Se was the main fraction (29.3%–61.7%) for selenate-treated soils, and which decreased significantly (52.5% for chestnut soil and 44.2% for black soil) and transformed to less labile fractions with ageing. By contrast, exchangeable Se fraction was the main fraction in selenite-treated soils, which decreased by 38%–71.8% with ageing. The DGT measurement (
C
DGT
) of selenate treatment was 1.8–96.7 times higher than that of selenite treatment. Dynamic analysis showed that shorter response time
T
c
(44 s) and higher desorption rate constant
k
−1
(≥ 1.5E-3 s
−1
) were observed in selenite-treated chestnut soil than black soil, which coincided with the higher Se contents in pak choi planted in chestnut soil than black soil. The opposite result was found for selenate, demonstrating that Se bioavailability was affected by soil properties and Se species.
Conclusions
This study demonstrated that DGT can describe the changes of Se bioavailability caused by ageing and predict Se uptake by pak choi roots in selenite- or selenate-aged soils.
Selenium is an essential trace element for mammals. Through selenoproteins, this mineral participates in various biological processes such as antioxidant defence, thyroid hormone production, and ...immune responses. Some reports indicate that a human organism deficient in selenium may be prone to certain diseases. Adverse health effects following selenium overexposure, although very rare, have been found in animals and people. Contrary to selenium, arsenic and cadmium are regarded as toxic elements. Both are environmental and industrial pollutants, and exposure to excessive amounts of arsenic or cadmium can pose a threat to many people's health, especially those living in polluted regions. Two other elements, vanadium and chromium(III) in trace amounts are believed to play essential physiological functions in mammals. This review summarizes recent studies on selenium interactions with arsenic and cadmium and selenium interactions with vanadium and chromium in mammals. Human studies have demonstrated that selenium may reduce arsenic accumulation in the organism and protect against arsenic-related skin lesions. Selenium was found to antagonise the prooxidant and genotoxic effects of arsenic in rodents and cell cultures. Also, studies on selenium effects against oxidative stress induced by cadmium in various animal tissues produced promising results. Reports suggest that selenium protection against toxicity of arsenic and cadmium is mediated via sequestration of these elements into biologically inert conjugates. Selenium-dependent antioxidant enzymes probably play a secondary role in arsenic and cadmium detoxification. So far, few studies have evaluated selenium effects on chromium(III) and vanadium actions in mammals. Still, they show that selenium may interact with these minerals. Taken together, the recent findings regarding selenium interaction with other elements extend our understanding of selenium biological functions and highlight selenium as a potential countermeasure against toxicity induced by arsenic and cadmium.PUBLICATION ABSTRACT
Coronavirus disease 2019 (COVID-19) is a global pandemic causing one of the biggest challenges for critical care medicine. Mortality from COVID-19 is much greater in elderly men, many of whom succumb ...to acute respiratory distress syndrome (ARDS) triggered by the viral infection. Because there is no specific antiviral treatment against COVID-19, new strategies are urgently needed. Selenium is an essential trace element with antioxidant and immunomodulatory effects. Poor nutritional status increases the pathogenicity of viruses and low selenium in particular can be a determinant of viral virulence. In the past decade, selenium pharmaconutrition studies have demonstrated some reduction in overall mortality, including how reduced incidence of ventilator-associated pneumonia and infectious complications such as ARDS in the critically ill. Consequently, we postulate that intravenous selenium therapy, could be part of the therapeutic fight against COVID-19 in intensive care unit patients with ARDS and that outcomes could be affected by age, sex, and body weight. Our working hypothesis addresses the question: Could high-dose selenite pharmaconutrition, as an early pharmacologic intervention, be effective at reducing the incidence and the progression from type 1 respiratory failure (non-ARDS) to severe ARDS, multiorgan failure, and new infectious complications in patients with COVID-19 patients?
•Poor selenium status is associated to viral virulence.•Selenium as selenite may be able to inhibit the entrance of severe acute respiratory syndrome coronavirus 2 in host cells, impeding its ability to infect healthy individuals.•We propose that high-dose selenite pharmaconutrition may be effective at reducing the incidence and progression of multiorgan failure, and new infections in patients with coronavirus disease 2019 (COVID-19).•We postulate that clinical outcomes could be affected by age, sex, and body weight.
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