Selenium: its role as antioxidant in human health

Antioxidant Properties of Selenophene, Thiophene and Their Aminocarbonitrile Derivatives

The oxygen radical absorbance capacity (ORAC) method was used to detect the antiperoxyradical ability of organoselenium compounds: selenophene and its derivative, 2-amino-4,5,6,7-tetrahydro-1-selenophene-3-carbonitrile (ATSe); while as a comparison, the sulfur-containing analogue of selenophene—thiophene and its derivative—2-amino-4,5,6,7-tetrahydro-1-thiophene-3-carbonitrile (ATS)—was selected. Cyclic voltammetry (CV), differential pulse voltammetry (DPV) and squarewave voltammetry (SWV) methods were used to determine the redox characteristics of organoselenium and organosulfur compounds. The antiradical activity and capacity of the studied compounds were also measured by using stable radical 2,2ʹ-diphenyl-1-picrylhydrazyl (DPPH). Detected anodic peaks of the oxidation of selenophene, thiophene and their derivatives in CV, DPV and SWV in the interval of −1200 ÷ (+1600) mV potentials in regard to the Ag/Ag⁺ medium of acetonitrile prove the presence of antiperoxyradical activity in regard to oxidizers, i.e., peroxyradicals. The chemical mechanism of the antiperoxyradical ability of selenophene, thiophene and their organic derivatives is proposed.

Low cadmium exposure in males and lactating females-estimation of biomarkers

BACKGROUND

Urine cadmium (Cd) and renal function biomarkers, mostly analysed in urine spot samples, are well established biomarkers of occupational exposure. Their use and associations at low environmental level are common, but have recently been questioned, particularly in terms of physiological variability and normalisation bias in the case of urine spot samples.

AIM

To determine the appropriateness of spot urine and/or blood Cd exposure biomarkers and their relationships with renal function biomarkers at low levels of exposure. To this end, we used data from Slovenian human biomonitoring program involving 1081 Slovenians (548 males, mean age 31 years; 533 lactating females, mean age 29 years; 2007-2015) who have not been exposed to Cd occupationally.

RESULTS

Geometric means (GMs) of Cd in blood and spot urine samples were 0.27ng/mL (0.28 for males and 0.33 for females) and 0.19ng/mL (0.21 for males and 0.17 for females), respectively. Differing results were obtained when contrasting normalisation by urine creatinine with specific gravity. GMs of urine albumin (Alb), alpha-1-microglobulin (A1M), N-acetyl-beta-glucosaminidase (NAG), and immunoglobulin G (IgG) were far below their upper reference limits. Statistical analysis of unnormalised or normalised urine data often yielded inconsistent and conflicting results (or trends), so association analyses with unnormalised data were taken as more valid. Relatively weak positive associations were observed between urine Cd (ng/mL) and blood Cd (β=0.11, p=0.002 for males and β=0.33, p<0.001 for females) and for females between urine NAG and blood Cd (β=0.14, p=0.04). No associations were found between other renal function biomarkers and blood Cd. Associations between Cd and renal function biomarkers in urine were stronger (p<0.05, β=0.11-0.63). Mostly, all of the associations stayed significant but weakened after normalisation for diuresis. In the case of A1M, its associations with Cd were influenced by current smoking and blood Pb in males and by pre-pregnancy smoking and blood Se in females (β up to 0.34, p<0.001). Statistical analysis of unnormalised or normalised urine data often yielded inconsistent and conflicting results (or trends), so association analyses data with unnormalised were taken as more valid.

CONCLUSIONS

The observed uncertainties introduced by urine normalisation, particularly by creatinine, confirm blood Cd as a superior low-Cd exposure biomarker versus urine Cd in cases when 24h urine is unattainable. Evidence that A1M can be positively related to Cd, smoking (current or pre-pregnancy), Pb, and Se status, points to the versatile biological functions of A1M.

Evaluation of selenium on kidney function following ischemic injury in rats; protective effects and antioxidant activity

Introduction: Renal dysfunction is caused by ischemia-reperfusion (I/R) injury, which is a common problem in kidney surgery or kidney transplantation. The human body consists of enormous complex antioxidant systems, which inquires adequate selenium (Se) absorption for normal physiologic function. It is known that Se has some antioxidant effects. Objectives: In the present research, effects of the Se on damages caused by I/R injury investigated. Materials and Methods: In this experimental research, four groups of rats (weighing 220±10 g) used, include control group, I/R group, healthy group treated with Se for two weeks, and I/R group with two-week Se treatment. On the test day, I/R was treated in both right and left renal arteries for 45 minutes and the reperfusion was done for 24 hours. Results: In I/R group, the amount of urea and serum creatinine (Cr) was an injury indicator of the kidney cells which showed a significant increase compared with the control group. When the treatment with Se significantly reduced these indicators, glutathione (GSH) enzyme levels reduced significantly in the second group and the enzyme levels increased due to Se treatment in the fourth group. Furthermore, malondialdehyde (MDA) enzyme levels increased in I/R group due to the Se treatment in the fourth group which was significantly reduced. In addition, the tissue damage was reduced in the fourth group compared with I/R group. Conclusion: Se has a protective effect against the I/R injury. This effect might be due to the antioxidant properties of Se.

Protective effect of selenium against cisplatin-induced nasopharyngeal cancer in male albino rats

The present study evaluated the protective effect of selenium against cisplatin-induced nasopharyngeal cancer in the cardiac tissue of adult rats. Male Wistar rats were divided into 4 groups of 6 rats each. Different combinations of selenium and cisplatin were administered for 45 days, following which the animals were sacrificed and the nasopharyngeal tissue was surgically removed. Lipid peroxidation, reduced glutathione, and the antioxidant enzymes superoxide dismutase (SOD), catalase and lactate dehydrogenase (LDH) were measured. Apoptotic-related gene (p53, bax and caspase 3) mRNA expression was determined using quantitative polymerase chain reaction. Caspase 3 activity was also measured in all the groups. The results demonstrated that selenium significantly reduced the levels of malondialdehyde. The levels of glutathione, SOD, LDH and catalase significantly increased following selenium treatment. Relative mRNA expression (p53, bax and caspase 3) was significantly reduced in the cisplatin-treated rats, but it significantly increased following selenium treatment. The anticancer activity of selenium was also investigated in HK1cells. Fluorescence and confocal microscopy were used to analyze apoptosis and reactive oxygen species. The protective effect of selenium was also evident through caspase 3 activity, which significantly increased following selenium treatment. Taken together, these results indicate that selenium may be beneficial against cisplatin-induced nasopharyngeal cancer.

Nineteen-year follow-up of a patient with severe glutathione synthetase deficiency

Glutathione synthetase deficiency is a rare autosomal recessive disorder resulting in low levels of glutathione and an increased susceptibility to oxidative stress. Patients with glutathione synthetase deficiency typically present in the neonatal period with hemolytic anemia, metabolic acidosis and neurological impairment. Lifelong treatment with antioxidants has been recommended in an attempt to prevent morbidity and mortality associated with the disorder. Here, we present a 19-year-old female who was diagnosed with glutathione synthetase deficiency shortly after birth and who has been closely followed in our metabolic clinic. Despite an initial severe presentation, she has had normal intellectual development and few complications of her disorder with a treatment regimen that includes polycitra (citric acid, potassium citrate and sodium citrate), vitamin C, vitamin E and selenium.

Effects of IL-33/ST2 pathway in acute inflammation on tissue damage, antioxidative parameters, magnesium concentration and cytokines profile

AIM

The aim of this study was to examine the role of IL-33/ST2 pathway in a pathogenesis of acute inflammation and its effects on tissue damage, antioxidative capacity, magnesium concentration and cytokine profile in acutely inflamed tissue.

MATERIAL AND METHODS

Male mice were randomly divided in four groups: wild-type control group (WT-C), ST2 knockout control group (KO-C), wild-type inflammatory group (WT-I), and ST2 knockout inflammatory group (KO-I). Acute inflammation was induced in WT-I and KO-I by intramuscular injection of turpentine oil, while mice in WT-C and KO-C were treated with saline. After 12h, animals were euthanized, and blood was collected for determination of creatine kinase (CK) and aspartate transaminase (AST) activity. The treated tissue was used for histopathological analysis, determination of volume density of inflammatory infiltrate (Vdii) and necrotic fiber (Vdnf), gene expression of interleukin (IL)-33, ST2, tumor necrosis factor alpha (TNF-alpha), IL-6, IL-12p35, and transforming growth factor beta (TGF-beta), concentration of magnesium (Mg), copper (Cu), selenium (Se), manganese (Mn) and reduced glutathione (GSH), and superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity.

RESULTS

Presence of inflammatory infiltration and necrosis in the treated tissue was histopathologically confirmed in WT-I and KO-I. Vdii was significantly higher in WT-I when compared to KO-I, whereas Vdnf did not significantly differ between WT-I and KO-I. CK and AST significantly increased in both inflammatory groups when compared to corresponding control groups. However, the values of CK and AST were significantly higher in WT-I than in KO-I. Mg in the treated tissue was significantly lower in WT-I in comparison to WT-C and KO-I, while there was no significant difference between KO-C and KO-I. There was no significant difference in Cu, Se, and Mn in the treated tissue between WT-C, KO-C, WT-I and KO-I. Gene expression of IL-33 in the treated tissue increased in both inflammatory groups when compared to the corresponding control groups, but it was significantly higher in KO-I than in WT-I. Gene expression of ST2 in the treated tissue was significantly higher in WT-I than in WT-C. Gene expression of TNF-alpha, IL-6, and IL-12p35 in the treated tissue was significantly higher in WT-I and KO-I than in the corresponding control groups, and IL-6 was significantly higher in KO-C than in WT-C. TGF-beta gene expression in the treated tissue was significantly higher in KO-I when compared to WT-I, while there was no difference between WT-C and KO-C. SOD activity decreased at the site of acute inflammation in both inflammatory groups, while the GPx activity increased. GSH in the treated tissue was significantly higher in KO-I than in KO-C or WT-I.

CONCLUSION

The results of our study have indicated, to our knowledge for the first time, that IL-33/ST2 pathway plays a role in enhancing inflammation and tissue damage at the site of acute inflammation by affecting the concentration of magnesium and GSH, important for antioxidative capacity, as well as gene expression of anti-inflammatory cytokine TGF-beta.

Selenium Digestibility and Bioactivity in Dogs: What the Can Can, the Kibble Can't

There is a growing concern for the long-term health effects of selenium (Se) over- or underfeeding. The efficiency of utilization of dietary Se is subject to many factors. Our study in dogs evaluated the effect of diet type (canned versus kibble) and dietary protein concentration on Se digestibility and bioactivity. Canned and kibble diets are commonly used formats of dog food, widely ranging in protein concentration. Twenty-four Labrador retrievers were used and four canned and four kibble diets were selected with crude protein concentrations ranging from 10.1 to 27.5 g/MJ. Crude protein concentration had no influence on the digestibility of Se in either canned or kibble diets, but a lower Se digestibility was observed in canned compared to kibble diets. However, the biological activity of Se, as measured by whole blood glutathione peroxidase, was higher in dogs fed the canned diets than in dogs fed the kibble diets and decreased with increasing crude protein intake. These results indicate that selenium recommendations in dog foods need to take diet type into account.

Ameliorative effect of selenium in cisplatin-induced testicular damage in rats

In this study, we investigated the protective effect of selenium (Se) on cisplatin (Cis) induced testicular damage using histopathological, immunohistochemical and biochemical approaches. Twenty-one male Wistar rats were equally divided into three groups of seven rats each: control (C), Cis, and Cis+Se. Cis and Cis+Se group rats received Cis at a dose of 12mg/kg b.w./day, intraperitoneally for 3 consecutive days. Cis+Se group rats received selenium via oral gavage 3mg/kg/day (twice-a day as 1.5mg/kg) until 11th consecutive days starting at 5 days before cisplatin injection. C group received only 0.9% NaCl intraperitoneally and orally at same time and at equal volume. After the treatment, the histopathological, immunohistochemical and biochemical examinations were performed. In seminiferous tubules of Cis treated rats were observed the most consistent findings characterized with vacuolization, desquamation, disorganization, and also was a considerable reduction in elongated spermatids, however the Cis+Se group exhibited improved histopathologic changes. In the immunohistochemical examinations, caspase-3 immunopositive cells displayed higher in the Cis group according to C and Cis+Se groups. Bcl-2 and NF-κB staining revealed a moderate number in the C group and significantly fewer in the Cis group compared to the Cis+Se groups. Additionally, MDA levels were also significantly increased in the Cis group in comparison to Control group, but pretreatment with selenium prevented elevation of MDA levels significantly in Cis+Se group rats. This study indicates that Cis-treatment induced testicular apoptosis and lipid peroxidation, and combined treatment with selenium prevented severity of the toxicity in rats.

HIV-1 Gag Blocks Selenite-Induced Stress Granule Assembly by Altering the mRNA Cap-Binding Complex

Stress granules (SGs) are dynamic accumulations of stalled preinitiation complexes and translational machinery that assemble under stressful conditions. Sodium selenite (Se) induces the assembly of noncanonical type II SGs that differ in morphology, composition, and mechanism of assembly from canonical SGs. Se inhibits translation initiation by altering the cap-binding activity of eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4EBP1). In this work, we show that human immunodeficiency virus type 1 (HIV-1) Gag is able to block the assembly of type II noncanonical SGs to facilitate continued Gag protein synthesis. We demonstrate that expression of Gag reduces the amount of hypophosphorylated 4EBP1 associated with the 5′ cap potentially through an interaction with its target, eIF4E. These results suggest that the assembly of SGs is an important host antiviral defense that HIV-1 has evolved for inhibition through several distinct mechanisms.

The antiviral stress response is an important host defense that many viruses, including HIV-1, have evolved to evade. Selenite induces a block in translation and leads to stress granule assembly through the sequestration of eIF4E by binding hypophosphorylated 4EBP1. In this work, we demonstrate that in the face of selenite-induced stress, HIV-1 is able to maintain Gag mRNA translation and to elicit a blockade to selenite-induced stress granule assembly by altering the amount of hypophosphorylated 4EBP1 on the 5′ cap.

Selenium and its relationship with selenoprotein P and glutathione peroxidase in children and adolescents with Hashimoto's thyroiditis and hypothyroidism

The essential trace element selenium (Se) is required for thyroid hormone synthesis and metabolism. Selenoproteins contain selenocysteine and are responsible for biological functions of selenium. Glutathione peroxidase (GPx) is one of the major selenoproteins which protects the thyroid cells from oxidative damage. Selenoprotein P (SePP) is considered as the plasma selenium transporter to tissues. The aim of this study was to evaluate serum Se and SePP levels, and GPx activity in erythrocytes of children and adolescents with treated Hashimoto's thyroiditis, hypothyroidism, and normal subjects. Blood samples were collected from 32 patients with Hashimoto's thyroiditis, 20 with hypothyroidism, and 25 matched normal subjects. All the patients were under treatment with levothyroxine and at the time of analysis all of the thyroid function tests were normal. GPx enzyme activity was measured by spectrophotometry at 340 nm. Serum selenium levels were measured by high-resolution continuum source graphite furnace atomic absorption. SePP, TPOAb (anti-thyroid peroxidase antibody), and TgAb (anti-thyroglobulin antibody) were determined by ELISA kits. T4, T3, T3 uptake and TSH were also measured. Neither GPx activity nor SePP levels were significantly different in patients with Hashimoto's thyroiditis or hypothyroidism compared to normal subjects. Although GPx and SePP were both lower in patients with hypothyroidism compared to those with Hashimoto's thyroiditis and normal subjects but the difference was not significant. Serum Se levels also did not differ significantly in patients and normal subjects. We did not find any correlation between GPx or SePP with TPOAb or TgAb but SePP was significantly correlated with Se. Results show that in patients with Hashimoto's thyroiditis or hypothyroidism who have been under treatment with levothyroxine and have normal thyroid function tests, the GPx, SePP and Se levels are not significantly different.

Improvement of Heart Redox States Contributes to the Beneficial Effects of Selenium Against Penconazole-Induced Cardiotoxicity in Adult Rats

The present study was performed to evaluate the protective effect of selenium (Se) against penconazole (PEN)-induced oxidative stress in the cardiac tissue of adult rats. Male Wistar rats were divided into four groups of six each. The first group represented the controls. For the second group (PEN), no treatment was performed during the first 6 days, and then, the rats received intraperitoneally 67 mg/kg body weight (bw) of PEN every 2 days from day 7 until day 15, the sacrifice day. For the third group (Se + PEN), Se was administered daily through the diet at a dose of 0.5 mg/kg of diet for 15 days. Rats of this group received also every 2 days PEN (67 mg/kg bw) from day 7 until day 15. The fourth group (Se) received daily, through the diet, Se (0.5 mg/Kg of diet) during 15 days. Our results showed that Se reduced significantly the elevated cardiac levels of malondialdehyde and protein carbonyl following PEN treatment, and attenuated DNA fragmentation induced by this fungicide. In addition, Se modulated the alterations of antioxidant status: enzymatic (superoxide dismutase, glutathione peroxidase, and catalase) and nonenzymatic (glutathione and vitamin C) antioxidants in the heart of PEN-treated rats. This trace element was also able to alleviate perturbations of lipid profile. The protective effect of selenium was further evident through the histopathological changes produced by PEN in the heart tissue. Taken together, our results indicated that Se might be beneficial against PEN-induced cardiac oxidative damage in rats.

Radioprotective Agents: Strategies and Translational Advances

Radioprotectors are agents required to protect biological system exposed to radiation, either naturally or through radiation leakage, and they protect normal cells from radiation injury in cancer patients undergoing radiotherapy. It is imperative to study radioprotectors and their mechanism of action comprehensively, looking at their potential therapeutic applications. This review intimately chronicles the rich intellectual, pharmacological story of natural and synthetic radioprotectors. A continuous effort is going on by researchers to develop clinically promising radioprotective agents. In this article, for the first time we have discussed the impact of radioprotectors on different signaling pathways in cells, which will create a basis for scientific community working in this area to develop novel molecules with better therapeutic efficacy. The bright future of exceptionally noncytotoxic derivatives of bisbenzimidazoles is also described as radiomodulators. Amifostine, an effective radioprotectant, has been approved by the FDA for limited clinical use. However, due to its adverse side effects, it is not routinely used clinically. Recently, CBLB502 and several analog of a peptide are under clinical trial and showed high success against radiotherapy in cancer. This article reviews the different types of radioprotective agents with emphasis on the strategies for the development of novel radioprotectors for drug development. In addition, direction for future strategies relevant to the development of radioprotectors is also addressed.

Phenylselenolate Mercury Alkyl Compounds, PhSeHgMe and PhSeHgEt: Molecular Structures, Protolytic Hg-C Bond Cleavage and Phenylselenolate Exchange

The phenylselenolate mercury alkyl compounds, PhSeHgMe and PhSeHgEt, have been structurally characterized by X-ray diffraction, thereby demonstrating that both compounds are monomeric with approximately linear coordination geometries; the mercury centers do, nevertheless, exhibit secondary Hg•••Se intermolecular interactions that serve to increase the coordination number in the solid state. The ethyl derivative, PhSeHgEt, undergoes facile protolytic cleavage of the Hg-C bond to release ethane at room temperature, whereas PhSeHgMe exhibits little reactivity under similar conditions. Interestingly, the cleavage of the Hg-C bond of PhSeHgEt is also more facile than that of the thiolate analogue, PhSHgEt, which demonstrates that coordination by selenium promotes protolytic cleavage of the mercury-carbon bond. The phenylselenolate compounds PhSeHgR (R = Me, Et) also undergo degenerate exchange reactions with, for example, PhSHgR and RHgCl. In each case, the alkyl groups preserve coupling to the 199Hg nuclei, thereby indicating that the exchange process involves metathesis of the Hg-SePh/Hg-X groups rather than metathesis of the Hg-R/Hg-R groups.

Possible Biomarkers in Blood for Crohn's Disease: Oxidative Stress and MicroRNAs-Current Evidences and Further Aspects to Unravel

Crohn's disease (CD) is an inflammatory disorder characterised by a transmural inflammation of the intestinal wall. Although the physiopathology of the disease is not yet fully understood, it is clear that the immune response plays an important role in it. This hyperreactive immune system is accompanied by the presence of unregulated reactive oxygen species (ROS). These elements are modulated in normal conditions by different elements, including enzymes that function as antioxidant defences preventing the harmful effects of ROS. However, in CD there is an imbalance between ROS production and these antioxidant elements, resulting in oxidative stress (OxS) phenomena. In fact, now OxS is being considered more a potential etiological factor for Crohn's disease rather than a concomitant effect in the disease. The persistence of the OxS can also be influencing the evolution of the disease. Furthermore, the epigenetic mechanisms, above all microRNAs, are being considered key elements in the pathogenesis of CD. These elements and the presence of OxS have also been linked to several diseases. We, therefore, describe in this review the most significant findings related to oxidative stress and microRNAs profiles in the peripheral blood of CD patients.

Selenite-induced autophagy antagonizes apoptosis in colorectal cancer cells in vitro and in vivo

In the present study, we aimed to investigate the relationship between autophagy and apoptosis in selenite-treated colorectal cancer (CRC) cells. The effects of selenite on HCT116 and SW480 cell apoptosis were investigated with an Annexin V/propidium iodide (PI) double staining kit by flow cytometry. The punctate of LC3 protein following treatment with selenite was observed by a laser scanning confocal microscope and by transmission electron microscopy. Using western blot assays, we detected the apoptotic and autophagic markers in both CRC cells and mouse xenograft tumor models. We found that sodium selenite induced autophagy in the two CRC cell lines. Consistent with the in vitro results, we observed that the expression of autophagy marker LC3 was increased. Finally, we discovered that modulation of reactive oxygen species by MnTMPyP inhibited autophagy, while H₂O₂ activated autophagy. These results help to elucidate the anticancer effect of selenium, providing further evidence to exploit novel anticancer drugs targeting selenium.

Levels of nutrients in relation to fish consumption among older male anglers in Wisconsin

Fish is an important source of nutrients including omega-3 fatty acids, which may reduce risk of adverse health outcomes such as cardiovascular disease; however, fish may also contain significant amounts of environmental pollutants. The Wisconsin Departments of Health Services and Natural Resources developed a survey instrument, along with a strategy to collect human biological samples to assess the risks and benefits associated with long-term fish consumption among older male anglers in Wisconsin. The target population was men aged 50 years and older, who fish Wisconsin waters and live in the state of Wisconsin. Participants provided blood and hair samples and completed a detailed (paper) questionnaire, which included questions on basic demographics, health status, location of catch and species of fish caught/eaten, consumption of locally caught and commercially purchased fish, and awareness and source of information for local and statewide consumption guidelines. Biological samples were used to assess levels of docosahexaenoic acid (DHA), docosapentaenoic acid (DPA), eicosapentaenoic acid (EPA); vitamin D; and selenium in blood. Quantile regression analysis was used to investigate the associations between biomarker levels and self-reported consumption of fish from the Great Lakes and other areas of concern, other locally caught fish, and commercially purchased fish (meals per year). Respondents were largely non-Hispanic white men in their 60's with at least some college education, and about half were retired. Fish consumption was high (median of 54.5 meals per year), with most fish meals coming from locally-caught fish. Multivariate regression models showed that the effect of supplement use was much greater than that of fish consumption, on nutrient levels, although consumption of fish from the Great Lakes and areas of concern was significantly associated with higher levels of vitamin D even after controlling for supplement usage.

The andrologist's contribution to a better life for ageing men: part 2

The long-term intake of a judiciously composed nutriceutical containing low-dose vitamins, antioxidants, minerals and particular herbal preparations seems justified for older persons who take medication, or who consume an unbalanced diet, or who are exposed to environmental toxins. Recent reports suggest these nutriceuticals may delay age-related diseases and the occurrence of cancer, and reduce mortality in apparently healthy ageing men. Food supplementation with a nutriceutical that was formulated particularly for ageing men should result in an increase of at least one quality-adjusted life year and may lower the financial and social burden of disease in elderly people.

Serum selenium and lipid levels: Associations observed in the National Health and Nutrition Examination Survey (NHANES) 2011-2012

Selenium is an essential micronutrient, and due to its antioxidant activity, is hypothesized to be beneficial to cardiovascular health. However, the evidence for an association between selenium and health markers such as lipid levels has been mixed. This may be due to substantial variability in the level of selenium intake between populations and potential non-linearity of selenium-health outcome associations. We used the 2011-2012 National Health and Nutrition Examination Survey (NHANES) to examine the relationship between serum selenium and lipid levels among participants aged 12 years and older. Associations were evaluated using both linear regression models, as well as ordinal logistic regression and quantile regression models to allow for potential non-linear relationships. In all models, potential confounders of sex, age group, race/ethnicity, educational attainment and cotinine were included. Overall, 40% of participants had total cholesterol levels classified as borderline or elevated, and total cholesterol increased with increasing selenium (p=0.01). A similar pattern was seen for triglycerides (p=0.02). LDL cholesterol was also associated with selenium but not in a linear fashion; HDL cholesterol did not vary with selenium. Multivariate quantile regression showed significant associations between selenium and total cholesterol, LDL cholesterol, and triglycerides. The effect of selenium was stronger with increasing quantile for total cholesterol and for triglycerides. In contrast, for LDL cholesterol the association was positive in the 10th and 50th percentiles, but (non-significant and) negative in the 90th percentile. These results show that while selenium may impact cardiovascular health via effects on lipid levels, the associations may not be linear.

L-selenomethionine reduces platinum(IV) anticancer model compounds at strikingly faster rates than L-methionine

L-Selenomethionine (SeMet), the predominant form of selenium acquired from the diet by humans, has been used as a supplement, and exhibit some important functions like cancer prevention and antioxidative defense. Its interactions with Pt(II) anticancer drugs have been characterized, but its redox reactions with platinum(IV) anticancer prodrugs have not been exploited. In this work, the oxidation of SeMet by Pt(IV) anticancer model compounds trans-[PtX2(CN)4](2-) (X = Cl, Br) was characterized. A stopped-flow spectrometer was used to record the rapid scan spectra and to follow the reaction kinetics over a wide pH range. An overall second-order rate law was derived: -d[Pt(IV)]/dt = k'[Pt(IV)][SeMet], where k' pertains to the observed second-order rate constants. The k'-pH profiles showed that k' increased only about 6 times even though the solution pH was varied from 0.25 to 10.5. The redox stoichiometry was determined as Δ[Pt(IV)]/Δ[SeMet] = 1 : (1.07 ± 0.07), suggesting that SeMet was oxidized to selenomethionine selenoxide. The selenoxide together with its hydrated form was identified explicitly by high resolution mass spectral analysis. A reaction mechanism was proposed which encompassed three parallel rate-determining steps relying on the protolytic species of SeMet. Rate constants of the rate-determining steps were obtained from the simulations of the k'-pH profiles. Activation parameters were determined for the reactions of the zwitterionic form of SeMet with the Pt(IV) complexes. A bridged electron transfer process is delineated in the rate-determining steps and several lines of evidence support the bridged electron transfer mode. Strikingly, reduction of [PtX2(CN)4](2-) by SeMet is 3.7 × 10(3)-5.7 × 10(4) times faster than that by L-methionine. Some potential biological consequences resulting from the strikingly fast reduction are discussed.

Roles of selenoprotein antioxidant protection in zebrafish, Danio rerio, subjected to dietary oxidative stress

In vertebrates, selenium (Se) is an essential micronutrient for vertebrates that is involved in antioxidant protection and thyroid hormone regulation among other roles and functions through its incorporation into proteins, the selenoproteins. Long-chain polyunsaturated fatty acids, such as docosahexaenoic acid (DHA), are essential nutrients for fish although high dietary levels may lead to increased oxidative stress due to the high degree of unsaturation. The present study investigated the effects of Se supplementation on zebrafish, Danio rerio, oxidative status together with selenoprotein expression profiles when subjected to a high-DHA diet. Fish were fed for 8 weeks with one of the four experimental diets, containing high or low DHA in combination with or without organic Se (7 mg/kg). Fish performance, Se content, fatty acid composition and TBARS of zebrafish were determined, as well as gene expression of selected selenoproteins in liver and muscle. The Se levels in whole fish reflected dietary content. High dietary DHA increased oxidative stress as indicated by reduced growth and high TBARS content, although Se supplementation reduced oxidation. The expression patterns of selenoproteins varied between liver and muscle with only deiodinase type II displaying a transcriptional response when high dietary Se was supplied. High dietary DHA decreased selenoprotein W expression in muscle and sps2 expression in liver regardless of the dietary Se content. These data suggest that oxidative stress protection associated with a high dietary intake of Se may not be solely mediated by transcriptional changes in teleost selenoprotein expression.

Effects of selenium on endothelial dysfunction and metabolic profile in low dose streptozotocin induced diabetic rats fed a high fat diet

Endothelial dysfunction develops as a result of oxidative stress and is responsible for diabetic vascular complications. We investigated the effects of selenium on endothelial dysfunction and oxidative stress in type 2 diabetic rats. Male Wistar rats were divided into five groups: controls, untreated diabetics, and diabetics treated with 180, 300, 500 mcg/kg selenium each day. Diabetes was induced by a single intraperitoneal injection of low dose streptozotocin to rats fed a high fat diet. Endothelium-dependent and -independent relaxations were measured in the thoracic aorta. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and endothelial nitric oxide synthase (eNOS) mRNA expressions were analyzed using real-time polymerase chain reaction (RT-PCR). Fasting blood glucose, lipid profile, lipid oxidation, insulin and nitric oxide were measured in blood samples. Malondialdehyde, superoxide dismutase, catalase and glutathione peroxidase levels were measured in liver samples. RT-PCR showed that selenium reversed increased NADPH oxidase expression and decreased eNOS expression to control levels. Selenium also improved the impairment of endothelium-dependent vasorelaxation in the diabetic aorta. Selenium treatment significantly decreased blood glucose, cholesterol and triglyceride levels, and enhanced the antioxidant status in diabetic rats. Our findings suggest that selenium restores a normal metabolic profile and ameliorates vascular responses and endothelial dysfunction in diabetes by regulating antioxidant enzyme and nitric oxide release.

Protolytic cleavage of Hg-C bonds induced by 1-methyl-1,3-dihydro-2H-benzimidazole-2-selone: synthesis and structural characterization of mercury complexes

Multinuclear ((1)H, (77)Se, and (199)Hg) NMR spectroscopy demonstrates that 1-methyl-1,3-dihydro-2H-benzimidazole-2-selone, H(sebenzim(Me)), a structural analogue of the selenoamino acid, selenoneine, binds rapidly and reversibly to the mercury centers of HgX2 (X = Cl, Br, I), while X-ray diffraction studies provide evidence for the existence of adducts of composition [H(sebenzim(Me))]xHgX2 (X = Cl, x = 2, 3, 4; X = I, x = 2) in the solid state. H(sebenzim(Me)) also reacts with methylmercury halides, but the reaction is accompanied by elimination of methane resulting from protolytic cleavage of the Hg-C bond, an observation that is of relevance to the report that selenoneine demethylates CysHgMe, thereby providing a mechanism for mercury detoxification. Interestingly, the structures of [H(sebenzim(Me))]xHgX2 exhibit a variety of different hydrogen bonding patterns resulting from the ability of the N-H groups to form hydrogen bonds with chlorine, iodine, and selenium.

Prevention of Aflatoxin B1 Hepatoxicity by Dietary Selenium Is Associated with Inhibition of Cytochrome P450 Isozymes and Up-Regulation of 6 Selenoprotein Genes in Chick Liver

BACKGROUND

The involvement of cytochrome P450 (CYP450) isozymes and the selenogenome in selenium-mediated protection against aflatoxin B1 (AFB1)-induced adverse effects in broilers remains unclear.

OBJECTIVE

This study was designed first to determine whether selenium could reduce AFB1-induced hepatotoxic effects and then to determine whether these effects were due to changes in the CYP450 isozymes and selenogenome expression in the liver of chicks.

METHODS

Male avian broilers (aged 120 d) were allocated to 4 groups with 5 replicates of 6 birds to be included in a 2-by-2 factorial trial in which the main factors included supplementation of AFB1 (<5 compared with 100 μg/kg) and selenium (0.2 compared with 0.5 mg/kg) in a corn/soybean-based diet for 4 wk. Serum biochemistry, hepatic histology, and mRNA and/or activities of hepatic antioxidant enzymes, CYP450 isozymes, and 26 selenoproteins were analyzed at week 2 and/or 4.

RESULTS

Administration of AFB1 induced liver injury, decreasing (P < 0.05) total protein and albumin concentrations by 33.3-43.8% and increasing (P < 0.05) alanine aminotransferase and aspartate aminotransferase activities by 26.0-33.8% in serum, and induced hepatic necrosis and bile duct hyperplasia at week 2. AFB1 also decreased (P < 0.05) hepatic activities of glutathione peroxidase (GPX), thioredoxin reductase (TXNRD), and catalase, and the glutathione concentration by 13.1-59.9% and increased (P < 0.05) malondialdehyde, 8-hydroxydeoxyguanosine and exo-AFB1-8,9-epoxide (AFBO) DNA concentrations by 17.9-1200%. In addition, the mRNA and activity of enzymes responsible for the bioactivation of AFB1 into AFBO, which included CYP450 A1, 1A2, 2A6, and 3A4, were significantly induced (P < 0.05) by 29.2-271% in liver microsomes after 2-wk exposure to AFB1. These alterations induced by AFB1 were prevented by selenium supplementation. Dietary selenium supplementation increased (P < 0.05) mRNA and/or activities of 6 selenoprotein genes (Gpx3, Txnrd1, Txnrd2, Txnrd3, iodothyronine deiodinase 2, and selenoprotein N) in the liver of AFB1-treated groups at week 2.

CONCLUSIONS

Dietary selenium protected chicks from AFB1-induced liver injury, potentially through the synergistic actions of inhibition of the pivotal CYP450 isozyme-mediated activation of AFB1 to toxic AFBO, and increased antioxidant capacities by upregulation of selenoprotein genes coding for antioxidant proteins.

The hypolipidemic and pleiotropic effects of rosuvastatin are not enhanced by its association with zinc and selenium supplementation in coronary artery disease patients: a double blind randomized controlled study

Objective

Statins treatment may modify the levels of zinc and selenium, minerals that can improve vascular function and reduce oxidative damage and inflammation in atherosclerotic patients. This study aimed to evaluate the effects of rosuvastatin, alone or associated with zinc and selenium supplementation, on lipid profile, antioxidant enzymes and mineral status in coronary artery disease patients.

Material and Methods

A double-blind randomized clinical trial was performed in which patients (n = 76) were treated with 10 mg rosuvastatin over 4 months associated or not with zinc (30 mg/d) and selenium (150 μg/d) supplementation. The following parameters were analyzed before and after the intervention: anthropometric measurements, lipid profile, high sensitivity C-reactive protein (hs-CRP), electronegative low density lipoprotein (LDL(-)) concentrations, activities of glutathione peroxidase (GPx), superoxide dismutase (SOD), zinc and selenium concentrations in blood plasma and erythocytes. Significance was determined using an α of 5% (two-tailed).

Results

We found that rosuvastatin therapy was efficient in reducing total cholesterol, LDL-cholesterol, non-HDL cholesterol, triglycerides, and hs-CRP independently of mineral supplementation. Neither treatment was associated with significant changes in LDL(-). Similarly, the antioxidant enzymes GPx and SOD activity were unchanged by treatments. Neither treatment was associated with significant differences in concentrations of zinc or selenium in blood plasma and erythocytes of studied groups.

Conclusion

Rosuvastatin treatment did not affect zinc and selenium levels in coronary artery disease patients. The zinc and selenium supplementation at doses used in this study did not change lipid profile or SOD and GPx activity in patients receiving rosuvastatin. Further studies should be focused on testing alternative doses and supplements in different populations to contribute for a consensus on the ideal choice of antioxidants to be used as possible complementary therapies in atherosclerotic patients.

Trial Registration

ClinicalTrials.gov NCT01547377

A case study evaluation of competitors undertaking an antarctic ultra-endurance event: nutrition, hydration and body composition variables

Background

The nutritional demands of ultra-endurance racing are well documented. However, the relationship between nutritional consumption and performance measures are less obvious for athletes competing in Polar conditions. Therefore, the aim of this study was to evaluate dietary intake, hydration status, body composition and performance times throughout an 800-km Antarctic race.

Methods

The event organisers declared that 17 competitors would participate in the South Pole race. Of the 17 competitors, pre-race data were collected from 13 participants (12 males and 1 female (M ± SD): age: 40.1 ± 8.9 years; weight: 83.9 ± 10.3 kg; and body fat percentage: 21.9 ± 3.8%). Dietary recall, body composition and urinary osmolarity were assessed pre-race, midway checkpoint and end race. Data were compared on the basis of fast finishers (the Norwegian team (n = 3) who won in a record of 14 days) and slower finishers (the remaining teams (n = 10) reaching the South Pole between 22 and 28 days).

Results

The percentage contribution of macronutrients to daily energy intake for all participants was as follows: carbohydrate (CHO) = 23.7% (221 ± 82 g.day⁻¹), fat = 60.6% (251 ± 127 g.day⁻¹) and protein = 15.7% (117 ± 52 g.day⁻¹). Energy demands were closer met by faster finishers compared to slower finishers (5,332 ± 469 vs. 3,048 ± 1,140 kcal.day⁻¹, p = 0.02). Average reduction in body mass throughout the race was 8.3 ± 5.5 kg, with an average loss of lean mass of 2.0 ± 4.1 kg. There was a significant negative correlation between changes in lean mass and protein intake (p = 0.03), and lean mass and energy intake (p = 0.03). End-race urinary osmolarity was significantly elevated for faster finishers compared to slower finishers and control volunteers (faster finishers: 933 ± 157 mOsmol.L⁻¹; slower finishers: 543 ± 92 mOsmol.L⁻¹; control: 515 ± 165 mOsmol.L⁻¹, p = 0.04).

Conclusions

Throughout the race, both groups were subjected to a negative change in energy balance which partly explained reduced body mass. Carbohydrate availability was limited inferring a greater reliance on fat and protein metabolism. Consequently, loss in fat-free mass was more prevalent with insufficient protein and caloric intake, which may relate to performance.

Effect of vitamin E supplementation on arsenic induced alteration in blood biochemical profile, oxidant/antioxidant status, serum cortisol level and retention of arsenic and selenium in goats

Arsenic (As) exerts oxidative stress with depletion of body selenium in monogastric animals. But in ruminants this fact is not yet verified. Vitamin E is an effective dietary antioxidant. Thus, in this experiment, the protective effect of vitamin E against arsenic toxicity induced by sodium arsenite (60mg As/kg diet) was investigated in goat kids. For this, 21 male kids were divided into three equal groups and fed either basal diet as such (control), or supplemented with 60mg As/kg diet and 60mg As/kg diet+250IU vitamin E/kg diet for 180 days. Vitamin E supplementation alleviated the toxic effects caused by arsenic on serum alanine aminotransferase and aspartate aminotransferase and lipid peroxidation. It also prevented the depletion of reduced glutathione content and reduction in activity of catalase, superoxide dismutase and glutathione-s-transferase in erythrocytes resulted from arsenic intoxication. The elevated levels of arsenic and reduced levels of selenium in the serum and tissues in arsenic treated animals were attenuated by vitamin E supplementation, though not completely. However, serum cortisol level was not affected by arsenic. It was concluded that arsenic exerts cortisol independent stressor mechanism and supplementation of vitamin E at a level of 250IU/kg diet was partially effective in reducing tissue accumulation of arsenic in the body and protect the kids from oxidative stress induced by arsenic.

The effect of dietary intake of antioxidant micronutrients on burn wound healing: a study in a tertiary health institution in a developing country

Background

Burn injury results in emotional stress affecting dietary intake and antioxidant micronutrient intake, which is known to have effects on recovery outcomes. The study aimed to assess dietary intake of antioxidant micronutrients and recovery outcomes of burn patients.

Methods

Questionnaires were administered to 40 burn patients at Komfo Anokye Teaching Hospital (Ghana) from January 1, 2014 to May 30, 2014. The data taken include anthropometric measurements and dietary assessment. Their nutrient intakes were assessed with the Nutrient Analysis Template. The average intakes were compared to the recommended daily allowance. Assessment of recovery was based on records of wound healing assessments and infection rates from the health practitioners.

Results

A cross-sectional study of 40 patients revealed an average total burn surface area (TBSA) of 31.4 %, where 70.0, 35.0, 75.0, 52.5, 12.5 and 32.5 % patients were deficient in vitamins A, C and E, zinc, copper and selenium, respectively and adequate amounts of vitamin C intake were related with significantly better wound healing progress. Positive wound healing outcomes were observed for patients with adequate vitamins A and E and zinc intake. Less infection presented among patients with adequate amount of vitamins A and C and zinc, but this was not observed for patients with adequate vitamin E, copper and selenium.

Conclusions

Most burn patients did not meet their dietary requirements for antioxidant micronutrients and this was due to meals not tailored to suit individual requirements. Adequacy of the antioxidants especially vitamin C resulted in positive wound healing outcomes. Hence, there is need for planned well-balanced meals of high vitamin C.

Protective effects of selenium against cadmium induced hematological disturbances, immunosuppressive, oxidative stress and hepatorenal damage in rats

Cadmium is a non-essential toxic metal used in industrial process, causes severe risk to human health. Selenium (Se) is an essential trace mineral of fundamental importance for human health. Selenium has antioxidant enzymes roles and is needed for the proper function of the immune system. In this study, the protective effects of selenium against cadmium intoxication in rats have been investigated by monitoring some selective cytokines (IL-1β, TNF α, IL-6, IL-10 and IFN-γ), antioxidant enzymes reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and lipid peroxidation malondialdehyde (MDA) as well as some selective biochemical markers of liver and kidney functions. Thirty-two rats were divided into four equal groups; the first group was used as a control. Groups 2-4 were treated with selenium (Se; 0.1mg/kg BW), cadmium (Cd; 40mg/L drinking water) and selenium plus cadmium, respectively. Rats were orally administered their relevant doses daily for 30 days. Blood samples were collected from heart puncture at the end of the experiment (30 days) for complete blood picture (CBC) and serum was separated to evaluate the different immunological parameters and biochemical parameters, as well as liver specimens for Cd and Se estimation. Rats in the Cd treated group have a significantly higher hepatic concentration of Cd than in other treated groups. Results revealed that cadmium significantly increased IL-1β, TNF α, IL-6 and IL-10, beside peripheral neutrophils count, while the IFN-γ and lymphocytes were decreased in rat sera. In addition, GSH level, CAT, SOD and GPx activities were significantly decreased while lipid peroxidation (MDA) was increased. Regarding, liver and renal markers, they were significantly increased in the activities of aminotransferases (AST, ALT), urea and creatinine, while total plasma proteins and albumin were significantly decreased. On the other hand, selenium treated group, showed significantly increased IFN-γ, GSH level, CAT, and GPx activities, as well as lymphocyte count while IL-10 was decreased. Selenium in combination with cadmium, significantly improved the elevation of serum IL-1β, IL-6, TNF α, IL-10 and malondialdehyde in addition to enhancing the antioxidant enzyme activities of GSH, CAT, GPx and SOD. Moreover, selenium has ameliorated the cadmium-induced liver and kidney damage by improving hepatic and renal markers. The results of this investigation demonstrated that selenium has the potential to countermeasure the immunosuppressive as well as hepatic and renal oxidative damage induced by cadmium in rats; selenium has shown promising effects against Cd toxicity.

Sulfur and selenium antioxidants: challenging radical scavenging mechanisms and developing structure-activity relationships based on metal binding

Because sulfur and selenium antioxidants can prevent oxidative damage, numerous animal and clinical trials have investigated the ability of these compounds to prevent the oxidative stress that is an underlying cause of cardiovascular disease, Alzheimer's disease, and cancer, among others. One of the most common sources of oxidative damage is metal-generated hydroxyl radical; however, very little research has focused on determining the metal-binding abilities and structural attributes that affect oxidative damage prevention by sulfur and selenium compounds. In this review, we describe our ongoing investigations into sulfur and selenium antioxidant prevention of iron- and copper-mediated oxidative DNA damage. We determined that many sulfur and selenium compounds inhibit Cu(I)-mediated DNA damage and that DNA damage prevention varies dramatically when Fe(II) is used in place of Cu(I) to generate hydroxyl radical. Oxidation potentials of the sulfur or selenium compounds do not correlate with their ability to prevent DNA damage, highlighting the importance of metal coordination rather than reactive oxygen species scavenging as an antioxidant mechanism. Additional gel electrophoresis, mass spectrometry, and UV-visible studies confirmed sulfur and selenium antioxidant binding to Cu(I) and Fe(II). Ultimately, our studies established that both the hydroxyl-radical-generating metal ion and the chemical environment of the sulfur or selenium significantly affect DNA damage prevention and that metal coordination is an essential mechanism for these antioxidants.

Evaluation of ameliorative potential of selenium on carbendazim induced oxidative stress in male goats

In the present investigation, ameliorative effect of selenium on carbendazim induced oral sub chronic toxicity in bucks was assessed by studying various indices of antioxidant defense system. Bucks were randomly divided into four groups of four animals each. Group I served as control, Group II was orally drenched carbendazim at the dose rate of 50mg/kg body weight for 90 consecutive days. Group III was orally administered selenium in the form of sodium selenite at the dose rate of 0.05mg/kg body weight for 90 consecutive days. Group IV was orally administered carbendazim along with selenium at the same dosages as Group II and III. Prolonged administration of carbendazim produced oxidative stress in goat bucks as evidenced by increase in lipid peroxidation and decline in total antioxidant capacity. The increase in the activity of antioxidant enzymes was not sufficient to prevent pesticide induced oxidative stress. Selenium supplementation provides some amelioration against this effect. Further study is needed to prove ameliorative potential of this antioxidant against carbendazim induced toxicity in goat bucks.

Nonsense-mediated decay factors are involved in the regulation of selenoprotein mRNA levels during selenium deficiency

Selenoproteins contain the unique amino acid selenocysteine (Sec), which is encoded by the triplet UGA. Since UGA also serves as a stop codon, it has been postulated that selenoprotein mRNAs are targeted for degradation by the nonsense-mediated mRNA decay pathway (NMD). Several reports have observed a hierarchy of selenoprotein mRNA expression when selenium (Se) is limiting, whereby the abundance of certain transcripts decline while others do not. We sought to investigate the role of NMD in this hierarchical response that selenoprotein mRNAs exhibit to environmental Se status. Selenoprotein mRNAs were categorized as being predicted sensitive or resistant to NMD based on the requirements held by the current model. About half of the selenoprotein transcriptome was predicted to be sensitive to NMD and showed significant changes in mRNA abundance in response to cellular Se status. The other half that was predicted to be resistant to NMD did not respond to Se status. RNA immunoprecipitation with essential NMD factor UPF1 revealed that the mRNAs that were the most sensitive to Se status were also the most enriched on UPF1 during Se deficiency. Furthermore, depletion of SMG1, the kinase responsible for UPF1 phosphorylation and NMD activation, abrogated the decline in transcript abundance of Se-responsive transcripts. Lastly, mRNA decay rates of Se-responsive transcripts were altered upon the addition of Se to resemble the slower decay rates of nonresponsive transcripts. Taken together, these results present novel evidence in support of a crucial role for the NMD pathway in regulating selenoprotein mRNA levels when Se is limiting.

Specific antioxidant compounds differentially modulate cytotoxic activity of doxorubicin and cisplatin: in vitro and in vivo study

Aim

To use the antioxidant compounds (sodium selenite, selenomethionine, D-pantethine) for modulation of cytotoxic effect of doxorubicin and cisplatin toward wild type and drug-resistant mutants of several human tumor cells. Similar treatments were applied in vivo toward adult male Wistar rats.

Methods

Human tumor cells of different lines (HCT-116, Jurkat and HL-60) with various mechanisms of drug-resistance were treated with doxorubicin or cisplatin, alone or in combination with sodium selenite, selenomethionine, or D-pantethine. Cell viability, induction of apoptosis, and production of O₂^- radicals were measured. Activity of redox potential modulating enzymes was measured in the liver and blood plasma of adult male Wistar rats subjected to similar treatments.

Results

All antioxidants used in physiologically harmless concentration inhibited cytotoxic action of doxorubicin toward tumor cells sensitive to chemotherapy treatment by 15%-30%, and slightly enhanced cytotoxic effect of this medicine toward drug-resistant malignant cells. At the same time, there was no significant effect of these antioxidants on cisplatin action. Such effects were accompanied by a complete inhibition of production of superoxide radicals induced by doxorubicin. The results of in vivo study in adult male Wistar rats were in agreement with the results of in vitro study of human tumor cells.

Conclusion

Protective effect of specific antioxidant agents during cytotoxic action of doxorubicin was demonstrated in vitro in drug-sensitive human tumor cells and in adult male Wistar rats, while there was no protective effect in drug-resistant sub-lines of these tumor cells during action of doxorubicin and cisplatin.

Photocatalytic removal of selenite and selenate species: effect of EDTA and other process variables

TiO2-assisted photocatalysis was employed for the removal of aqueous phase selenite and selenate species in conjunction with EDTA as a hole (h+) scavenger. Findings from the binary selenite/EDTA and selenate/EDTA systems showed high selenite and selenate removal at pH 4 and pH 6, with faster removal kinetics noted for the selenite species compared with the selenate species that showed a gradual change over the reaction course. The noted removal of selenite and selenate was attributed to their reduction by the conduction band electrons (e-). The effect of pH studies indicated high selenite, selenate, and EDTA removal in the acidic pH range, with the following specific trend: pH 4 > pH 6 > pH 12. Different from the EDTA studies, the use of thiocyanate alone did not initiate reduction of selenium oxyanions, and hence, its role as a hole scavenger in the present systems was not evident. However, the addition of EDTA to respective selenite/selenate/thiocyanate system at pH 4 did yield near complete removal of selenite and selenate species. The marginal role of thiocyanate as a hole scavenger was attributed to its negligible adsorption onto TiO2 surface. Furthermore, at pH 4 and within 3 h reaction time, enhanced selenate removal was noted with an increase in its initial concentration from 20 to 100 ppm, with near complete selenate removal noted for both cases. In general, findings from the present work indicate that both selenite and selenate can be successfully removed from the aqueous phase employing the TiO2-mediated photocatalysis and h(+)-scavenging agent EDTA.

Antioxidant activities of Se-SPI produced from soybean as accumulation and biotransformation reactor of natural selenium

A study to compare the uptake, translocation, and distribution of selenium (Se) in soybean planted in natural seleniferous soil in Fengcheng city of China was conducted to clarify the relationship between the Se content levels of soybean proteins and their radical scavenging activity. The data showed that the total Se content in different parts of soybean plants varied with the growth periods. The selenoprotein (Se-SPI) content increased remarkably with the increase of Se content in seleniferous soils. The Se-SPI content obtained from the region with the highest Se level was almost 18 times higher than that of the control group, while antioxidant activities were about 4-fold compared to the control, suggesting that Se played a positive role in enhancing the antioxidant activity of Se-SPI. The increase in the Se level also led to changes in amino acids composition, but with nearly no effects on the subunit composition of soybean Se-SPI.

Potential role of carotenoids as antioxidants in human health and disease

Carotenoids constitute a ubiquitous group of isoprenoid pigments. They are very efficient physical quenchers of singlet oxygen and scavengers of other reactive oxygen species. Carotenoids can also act as chemical quenchers undergoing irreversible oxygenation. The molecular mechanisms underlying these reactions are still not fully understood, especially in the context of the anti- and pro-oxidant activity of carotenoids, which, although not synthesized by humans and animals, are also present in their blood and tissues, contributing to a number of biochemical processes. The antioxidant potential of carotenoids is of particular significance to human health, due to the fact that losing antioxidant-reactive oxygen species balance results in “oxidative stress”, a critical factor of the pathogenic processes of various chronic disorders. Data coming from epidemiological studies and clinical trials strongly support the observation that adequate carotenoid supplementation may significantly reduce the risk of several disorders mediated by reactive oxygen species. Here, we would like to highlight the beneficial (protective) effects of dietary carotenoid intake in exemplary widespread modern civilization diseases, i.e., cancer, cardiovascular or photosensitivity disorders, in the context of carotenoids’ unique antioxidative properties.

Efficacy of supplementation of selected medicinal mushrooms with inorganic selenium salts

The aim of the study was to evaluate the possibility of supplementation with inorganic forms of selenium (Na2SeO4 and Na2SeO3) in concentrations of 0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0 and 1.5 mM of three medicinal mushroom species: Agrocybe aegerita, Hericium erinaceus and Ganoderma lucidum. Tested mushroom species grew in Se additions of 0-0.6 mM (A. aegerita and H. erinaceus), while growth of G. lucidum bodies was observed for 0-0.8 mM. For the latter mushroom species, the total Se content was the highest. Content of Seorg was diverse; for control bodies it was the highest for G. lucidum (only organic forms were present), lower for A. aegerita (84% organic forms) and the lowest for H. erinaceus (56% organic forms). Accumulation of Se(IV) was generally significantly higher than Se(VI) for all tested mushroom species. There was no significant decrease of A. aegerita or G. lucidum biomass with the exception of G. lucidum bodies growing under 0.8 mM of Se species addition (15.51 ± 6.53 g). Biomass of H. erinaceus bodies was the highest under 0.2 (197.04 ± 8.73 g), control (191.80 ± 6.06 g) and 0.1 mM (185.04 ± 8.73 g) of both inorganic salts. The addition to the medium of Se salts brought about macroscopic changes in the fruiting bodies of the examined mushrooms. Concentrations exceeding 0.4 mM caused diminution of carpophores or even their total absence. In addition, colour changes of fruiting bodies were also recorded. At Se concentrations of 0.4 and 0.6 mM, A. aegerita fruiting bodies were distinctly lighter and those of H. erinaceus changed colour from purely white to white-pink.

Serum selenium levels and oxidative balance as differential markers in hepatic damage caused by alcohol

AIMS

Antioxidant system abnormalities have been associated with ethanol consumption. This study examines the effects of chronic ethanol consumption on oxidative balance, including selenium (Se) levels in alcoholic patients with or without liver disease, and if these measurements could be indicative of liver disease.

MAIN METHODS

Serum Se levels, antioxidant enzymes' activities, malondialdehyde (MDA) and protein carbonyl (PC) were determined in three groups of patients: alcoholics without liver disease, alcoholics with liver disease, and non-alcoholics with liver disease; and in healthy volunteers.

KEY FINDINGS

Serum Se levels were lower in alcoholic patients and in patients affected by liver disease and especially lower in the alcoholic liver disease group. These values were correlated with the activity of glutathione peroxidase (GPx), the antioxidant selenoprotein. The antioxidant activities of the glutathione reductase (GR) and superoxide dismutase (SOD) were also lower in the three non-healthy groups. However, GR activity decreased and SOD activity increased in the non-alcoholic liver disease group versus alcoholic groups. Higher concentrations of PC in serum were found in non-healthy groups and were higher in alcoholic patients who also showed higher MDA levels. The highest MDA and PC levels were found in the alcoholic liver disease group.

SIGNIFICANCE

We conclude that serum Se levels are drastically decreased in alcoholic liver disease patients, showing that this element has a direct correlation with GPx activity, and lipid oxidation, suggesting that the serum Se/MDA ratio could be an indicator of hepatic damage caused by alcohol consumption, and pointing to Se as a possible antioxidant therapy.

Does active Crohn's disease have decreased intestinal antioxidant capacity?

BACKGROUND AND AIMS

Oxidative stress is presumed to play an important role in Crohn's disease (CD) pathogenesis. Nevertheless, the evaluation of the intestinal antioxidant capacity through the analysis of glutathione peroxidase activity in CD remains to be determined.

METHODS

20 CD outpatients and 16 volunteers going through colonic cancer screening were enrolled. Colonoscopy with biopsies was performed in all individuals. Samples from inflamed and non-inflamed mucosa were taken when there was CD endoscopic activity. Spectrophotometric assays were performed to measure tissue glutathione peroxidase (GPx) activity, and total (GSHT) and oxidized (GSSG) glutathione in all samples. Demographics and clinical characteristics were collected from clinical charts.

RESULTS

Inflamed CD mucosa presented reduced GPx activity compared to non-inflamed CD mucosa (42.94mU/mg protein vs 79.62mU/mg protein, P<0.05) and control mucosa (42.94mU/mg protein vs 95.08mU/mg protein, P<0.001). GSHT concentration was reduced in inflamed mucosa when compared to non-inflamed CD mucosa (0.78μmol/g vs 1.98μmol/g, P<0.01) and the control group (0.78μmol/g vs 2.11μmol/g, P<0.001). A significant correlation was detected between GPx activity and GSSG (r=-0.599), disease duration (r=0.546), and thiopurine treatment (r=-0.480) in non-inflamed CD mucosa.

CONCLUSION

Our findings suggest that reduced GPx activity is present in inflamed CD mucosa. In addition, endoscopic activity, disease duration and thiopurine therapy could be associated with mucosal decreased antioxidant activity.

Selenium-enriched Agaricus bisporus increases expression and activity of glutathione peroxidase-1 and expression of glutathione peroxidase-2 in rat colon

The effect of dietary supplementation with Se-enriched Agaricus bisporus on cytosolic gluthathione peroxidase-1 (GPx-1), gastrointestinal specific glutathione peroxidase-2 (GPx-2), thioredoxin reductase-1 (TrxR-1) and selenoprotein P (SeP) mRNA expression and GPx-1 enzyme activity in rat colon was examined. Rats were fed for 5weeks with control diet (0.15μg Se/g feed) or Se-enriched diet fortified with selenised mushroom (1μg Se/g feed). The mRNA expression levels were found to be significantly (P<0.01) up-regulated by 1.65-fold and 2.3-fold for GPx-1 and GPx-2, respectively, but were not significantly different for TrxR-1 and SeP between the 2 diet treatments. The up-regulation of GPx-1 mRNA expression was consistent with GPX-1 activity level, which was significantly (P<0.05) increased by 1.77-fold in rats fed with the Se-enriched diet compared to the control diet. The results showed that selenised A. bisporus can positively increase GPx-1 and GPx-2 gene expression and GPx-1 enzyme activity in rat colon.