Acute and Subchronic Toxicity Studies on Sel-Plex®, a Standardized, Registered High-selenium Yeast

A novel diselenide attenuates the carrageenan-induced inflammation by reducing neutrophil infiltration and the resulting tissue damage in mice

Selenium-containing compounds have emerged as promising treatment for redox-based and inflammatory diseases. This study aimed to investigate the in vitro and in vivo anti-inflammatory activity of a novel diselenide named as dibenzyl[diselanediyIbis(propane-3-1diyl)] dicarbamate (DD). DD reacted with HOCl (k = 9.2 x 107 M-1s-1), like glutathione (k = 1.2 x 108 M-1s-1), yielding seleninic and selenonic acid derivatives, and it also decreased HOCl formation by activated human neutrophils (IC50=4.6 μM) and purified myeloperoxidase (MPO) (IC50=3.8 μM). However, tyrosine, MPO-I and MPO-II substrates, did not restore HOCl formation in presence of DD. DD inhibited the oxidative burst in dHL-60 cells with no toxicity up to 25 µM for 48h. Next, an intraperitoneal administration of 25, 50, and 75 mg/kg DD decreased total leukocyte, neutrophil chemotaxis, and inflammation markers (MPO activity, lipid peroxidation, albumin exudation, nitrite, TNF-α, IL-1β, CXCL1/KC, and CXCL2/MIP-2) on a murine model of carrageenan-induced peritonitis. Likewise, 50 mg/kg DD (i.p.) decreased carrageenan-induced paw edema over 5h. Histological and immunohistochemistry analyses of the paw tissue showed decreased neutrophil count, edema area, and MPO, carbonylated, and nitrated protein staining. Furthermore, DD treatment decreased the fMLP-induced chemotaxis of human neutrophils (IC50=3.7 μM) in vitro with no toxicity. Lastly, DD presented no toxicity in a single-dose model using mice (50 mg/kg, i.p.) over 15 days and in Artemia salina bioassay (50 to 2000 µM), corroborating findings from in silico toxicological study. Altogether, these results demonstrate that DD attenuates carrageenan-induced inflammation mainly by reducing neutrophil migration and the resulting damage from MPO-mediated oxidative burst.

Systemic subchronic toxicity and comparison of four selenium nutritional supplements by 90-day oral exposure in Sprague-Dawley rats

To evaluate and compare the safety of four selenium supplements, namely Se-enriched peptides (SeP), yeast selenium (SeY), L-Se-methylselenocysteine (L-SeMc) and sodium selenite (Na2SeO3), the subchronic toxicity study was designed by 90-day gavage administration in Sprague-Dawley rats. The doses of SeP, SeY, L-SeMc and Na2SeO3 were 0.15, 0.30 and 0.60 mg/kg bw/day, with additional dose of 0.45 mg/kg L-SeMc (All dose calculated as Se). Symptoms like growling, hair loss and significant weight loss were found at 0.60 mg/kg of L-SeMc, but not in other groups. At the dose of 0.60 mg/kg, females in Na2SeO3, SeY and L-SeMc groups showed significant elevations in ALT and/or ALP. Pathologic manifestations such as bile duct hyperplasia and cholestasis were predominantly found in females at 0.6 mg/kg of L-SeMc and SeY groups, and in males at same dose of L-SeMc group showed marked testicular atrophy. 0.60 mg/kg of SeY and Na2SeO3, and 0.30, 0.45, 0.60 mg/kg of L-SeMc induced significant reductions in sperm motility rates, rapid movement and amount. In conclusion, the NOAEL of SeP, SeY, L-SeMc, Na2SeO3 was all 0.30 mg/kg for female, and 0.60, 0.30, 0.15 and 0.30 mg/kg for male respectively. Liver and reproductive organs are possible toxic target organs of hyper selenium.

The user safety assessment of a selenized yeast feed additive

Purpose: Of the several selenized yeasts authorised for use as feed additives in the EU, Saccharomyces cerevisiae CNCM I-3060 inactivated' (Sel-Plex^®), was the first to be approved for use, in 2006. The additive has a concentration of selenium between 2000 and 2400 mg/kg and a selenomethionine content greater than 63%. Previous toxicological and safety studies have shown Sel-Plex^® to be safe for use for target animal species, consumers, users and the environment. A new formulation of Sel-Plex^® was recently developed however, with a minimum selenium content of 3000 mg/kg. The increase in selenium in this product, Sel-Plex^® 3000, presented the need to assess the risk for workers and users and to establish if there would be any eye and/or skin irritancy and skin sensitisation effects associated with the product. The purpose of this paper is to present the methodology and results of the user safety skin and eye studies performed on Sel-Plex^® 3000.Materials & Methods: In vitro skin and eye models were used to assess skin and eye irritancy, while skin sensitisation was examined using an in vivo method. The acute eye irritation was evaluated using a Reconstructed human Cornea-like Epithelium (RhCE) model, which followed the OECD guideline 492. The skin irritation was assessed based on its ability to induce cell death in a commercial reconstructed human epidermis (RhE) model (EPISKIN™) according to the OECD Guideline No. 439. The skin sensitising potential was evaluated in the Guinea pig in line with OECD Guideline 406, and measured the extent and degree of skin reaction to a challenge exposure following previous topical exposure of a substance on the skin.Results: The skin and eye irritation test results showed that Sel-Plex^® 3000 was a non-irritant in both cases. The skin sensitisation study showed that the additive did not generate a sensitisation response in the guinea pig and should not be considered a skin sensitiser.Conclusion: These results indicate that Sel-Plex^® 3000 is safe to use for workers in an industrial setting when handling the product and the studies may be further used to support regulatory compliance in respective markets.

Chronic Intestinal Disorders in Humans and Pets: Current Management and the Potential of Nutraceutical Antioxidants as Alternatives

Simple Summary

Chronic disorders of the intestinal tract (CID) are characterized by signs of inflammation of the intestine for a period of at least three weeks. Both humans and pets can be affected by these disorders. Different therapeutic approaches can be selected to treat patients and the use of natural products has been increased in the last decade, since oxidative stress plays a key role in the progression of the chronic intestinal disorders. In this review, the antioxidant proprieties of several natural products with potential for treatment of CID in human and veterinary medicine are highlighted. Unfortunately, few clinical trials report the use of these products for treating CID in humans and none in animals.

Abstract

Chronic intestinal disorders (CID) are characterized by persistent, or recurrent gastrointestinal (GI) signs present for at least three weeks. In human medicine, inflammatory bowel disease (IBD) is a group of chronic GI diseases and includes Crohn’s disease (CD) and ulcerative colitis (UC). On the other hand, the general term chronic enteropathies (CE) is preferred in veterinary medicine. Different therapeutic approaches to these diseases are used in both humans and pets. This review is focused on the use of traditional therapies and nutraceuticals with specific antioxidant properties, for the treatment of CID in humans and animal patients. There is strong evidence of the antioxidant properties of the nutraceuticals included in this review, but few studies report their use for treating CID in humans and none in animals. Despite this fact, the majority of the nutraceuticals described in the present article could be considered as promising alternatives for the regular treatment of CID in human and veterinary medicine.

Selenium and Dogs: A Systematic Review

The intent of this review is to summarize the knowledge about selenium and its function in a dog's body. For this purpose, systematic literature search was conducted. For mammals, including dogs, a balanced diet and sufficient intake of selenium are important for correct function of metabolism. As for selenium poisoning, there are no naturally occurring cases known. Nowadays, we do not encounter clinical signs of its deficiency either, but it can be subclinical. For now, the most reliable method of assessing selenium status of a dog is measuring serum or plasma levels. Levels in full blood can be measured too, but there are no reference values. The use of glutathione peroxidase as an indirect assay is questionable in canines. Commercial dog food manufactures follow recommendations for minimal and maximal selenium levels and so dogs fed commercial diets should have balanced intake of selenium. For dogs fed home-made diets, complex data are missing. However, subclinical deficiency seems to affect, for example, male fertility or recovery from parasitical diseases. Very interesting is the role of selenium in prevention and treatment of cancer.

Systematic acute and subchronic toxicity evaluation of polysaccharide-protein complex-functionalized selenium nanoparticles with anticancer potency

Functionalized selenium nanoparticles (SeNPs) have demonstrated potential for applications in cancer chemotherapy, radio-sensitization, nephroprotection and drug delivery. However, their clinical application requires further systemic safety evaluation. Therefore, in this study, we examine the systematic acute and subchronic toxicity of polysaccharide-protein complex coated SeNPs (PTR-SeNPs). These particles exhibited a low oral acute toxicity (higher LD50) in SPF grade ICR mice and SD rats, and the evaluation of subchronic toxicity demonstrated that the no observed effect level (NOAEL) of the PTR-SeNPs was less than 200 μg Se per kg BW per day, which is about 30 times the tolerable upper intake levels of Se in the human body. In addition, we also found that, under a safe dose (0.75-7.5 mg kg-1), the oral administration of PTR-SeNPs dramatically inhibited the growth of cancer in a tumor-bearing nude mouse model, and the results of the histological analysis indicated that PTR-SeNPs did not significantly damage the major organs, including the liver, spleen, heart, kidneys and lungs. Moreover, the induction of caspase activation and mitochondrial dysfunction was the major anticancer action mechanism of PTR-SeNPs. Taken together, the results of this study provide a simple approach for the facile and large-scale manufacturing of SeNPs with reduced toxicity and enhanced anticancer activity through the regulation of the surface properties of SeNPs. Furthermore, this study generates evidence for the future exploration and translational application of these materials through oral administration in nanomedicine and nutritional sciences.

Assessment of the application for renewal of authorisation of selenomethionine produced by Saccharomyces cerevisiae CNCM I-3060 (selenised yeast inactivated) for all animal species

The Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the application for renewal of authorisation of organic form of selenium produced by Saccharomyces cerevisiae CNCM I-3060 (selenised yeast inactivated) (Sel-Plex®) for all animal species. In 2006, the FEEDAP Panel delivered an opinion on the safety and efficacy of the additive; subsequently it was authorised in the EU. The evidence provided indicates that the additive currently in the market complies with the conditions of authorisation. No new evidence was found that would make the FEEDAP Panel reconsidering its previous conclusions in the safety for target species, consumers and environment. In particular, the Panel confirms that the use of Sel-Plex® in animal nutrition does not pose a risk to consumers provided that the maximum selenium supplementation of 0.2 mg/kg feed from Sel-Plex® is not exceeded, yet respecting the maximum total selenium in feed of 0.5 mg/kg. In the context of the current application, the Panel reviewed toxicological studies; based on two repeated-dose studies on rats and dogs, it is concluded that the toxic potential of Sel-Plex® is only related to its selenium content. New data on characterisation of the additive and studies on effects on skin and eyes led the Panel reconsider the safety for the user. The Panel concluded that the additive is hazardous upon inhalation and a likely respiratory sensitiser; owing to the high dusting potential, persons handling the additive are at risk by inhalation. It is considered not irritant to the eyes and skin. A recommendation regarding the denomination of the additive under assessment was proposed by the Panel.

The Hepatoprotective Effect of Selenium-Enriched Yeast and Gum Arabic Combination on Carbon Tetrachloride-Induced Chronic Liver Injury in Rats

The antioxidant and anti-inflammatory effects of selenium-enriched yeast (SY) and Gum Arabic (GA) have been reported. This study aimed to determine the hepatoprotective effect of SY and GA combination on carbon tetrachloride (CCl₄ )-induced chronic liver injury in rats and to explore their synergistic mechanisms of action. Forty adult male Wistar rats randomly allotted to 5 groups: (A) worked as control, (B) was administered CCl₄ , (C-E) were fed daily by GA, SY, and GA+SY respectively after mixing with basal diet, following CCl₄ -intoxication. GA and SY combination significantly ameliorated CCl₄ -induced reduction in serum total protein with elevation in aspartate transaminase (AST) and alanine transaminase (ALT) in addition to restoring the histopathological changes and hepatic content of hydroxyproline. GA and SY combination was also effective in reducing lipid peroxidation (MDA), consistent with an increase in total antioxidant capacity (T-AOC), glutathione (GSH), superoxide dismutase (SOD) activities, indicating the suppression of liver oxidative stress. Furthermore, liver inflammation was ameliorated by GA and SY combination through inhibition of nuclear factor-kappa (NF-κB), tumor necrosis factor-alpha (TNF-α), cyclooxygenase-2(COX-2), monocyte chemotactic protein-1 (MCP-1), and toll-like receptor 4(TLR-4) over expression in the liver. Moreover, the up-regulation of proliferating cell nuclear antigen (PCNA) expression by GA and SY combination enhanced the regeneration of liver tissue after CCl₄ -administration. The expression of Collagen1, alpha-smooth muscle actin (α-SMA), and transforming growth factor-beta1 (TGFβ1), was obviously ameliorated by GA and SY combination, suggesting the amelioration of profibrotic response of the liver. Taken together, our current study suggests that GA and SY combination exhibit a significant hepatoprotective activity, which more efficient than GA or SY alone.

PRACTICAL APPLICATION

Chronic liver diseases are the serious health problems, which increase the morbidity and mortality in the world today. Selenium-enriched yeast (SY) and Gum Arabic (GA) combination might be potential dietary agents could obviously ameliorate chronic liver damage, higher than GA and SY alone. They act to suppress the inflammation and inhibit the profibrotic response as well as support the liver regeneration.

The Protective Effect of Selenium on Chronic Zearalenone-Induced Reproductive System Damage in Male Mice

This study aims to explore the protective effect of selenium (Se) on chronic zearalenone (ZEN)-induced reproductive system damage in male mice and the possible protective molecular mechanism against this. The chronic ZEN-induced injury mouse model was established with the continuous intragastric administration of 40 mg/kg body mass (B.M.) ZEN for 28 days. Then, interventions with different doses (0.1, 0.2, and 0.4 mg/kg B.M.) of Se were conducted on mice to analyse the changes in organ indexes of epididymis and testis, antioxidant capability of testis, serum level of testosterone, sperm concentration and motility parameters, and the expression levels of apoptosis-associated genes and blood testis barrier- (BTB) related genes. Our results showed that Se could greatly improve the ZEN-induced decrease of epididymis indexes and testis indexes. Results also showed that the decrease in sperm concentration, sperm normality rate, and sperm motility parameters, including percentage of motile sperm (motile), tropism percentage (progressive) and sperm average path velocity (VAP), caused by ZEN were elevated upon administration of the higher dose (0.4 mg/kg) and intermediate dose (0.2 mg/kg) of Se. Selenium also significantly reduced the content of malondialdehyde (MDA) but enhanced the activities of antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx) in the testis tissue. Further research demonstrated that ZEN increased the level of mRNA expression of BCL2-associated X protein (Bax) and caspase 3 (Casp3), decreased the level of mRNA expression of B cell leukemia/lymphoma 2 (Bcl2), vimentin (Vim) and cadherin 2 (Cdh2), whereas the co-administration of Se reversed these gene expression levels. Our results indicated that high levels of Se could protect against reproductive system damage in male mice caused by ZEN and the mechanism might such be that Se improved mice antioxidant ability, inhibited reproductive cell apoptosis, and increased the decrease of BTB integrity-related genes caused by ZEN.

The Influence of Selenium Yeast on Hematological, Biochemical and Reproductive Hormone Level Changes in Kunming Mice Following Acute Exposure to Zearalenone

Healthy male Kunming mice received selenium yeast for 14 days prior to a single oral administration of zearalenone (ZEN). After 48 h, blood samples were collected for analysis and showed that mice in the ZEN-treated group has significantly decreased lymphocytes (P < 0.05) and platelets (P < 0.05) along with an increased white blood cell (WBC) count and other constituents (P < 0.05). The serum biochemistry analysis of the ZEN group indicated that glutamic pyruvic transaminase (ALT), glutamic oxaloacetic transaminase (AST), urea, and uric acid were significantly increased (P < 0.05), whilst total bilirubin (TB) and albumin (ALB) were decreased along with serum testosterone and estrogen (P < 0. 05). The level of malondialdehyde (MDA) in the serum of the ZEN group was significantly increased whilst glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) had significantly decreased (P < 0.05). Treatment with selenium yeast had a significant effect on response with most of the experimental parameters returning to levels similar to those observed in the untreated control mice. From these data, it can be concluded that ZEN is highly poisonous in Kunming mice with high levels of toxicity on the blood, liver, and kidneys. High levels of oxidative stress were observed in mice and pre-treatment with selenium yeast by oral gavage is effective in the ameliorated effects of ZEN-induced damage.

Dietary Supplementation with Organoselenium Accelerates Recovery of Bladder Expression, but Does Not Improve Locomotor Function, following Spinal Cord Injury

Selenium is an essential element required for activity of several antioxidant enzymes, including glutathione peroxidase. Because of the critical role of the antioxidant system in responding to traumatic events, we hypothesized that dietary selenium supplementation would enhance neuroprotection in a rodent model of spinal cord injury. Rats were maintained on either a control or selenium-enriched diet prior to, and following, injury. Dietary selenium supplementation, provided as selenized yeast added to normal rat chow, resulted in a doubling of selenium levels in the spinal cord. Dietary selenium reduced the time required for recovery of bladder function following thoracic spinal cord injury. However, this was not accompanied by improvement in locomotor function or tissue sparing.

Alteration of osteocalcin mRNA expression in ovine osteoblasts in dependence of sodium fluoride and sodium selenite medium supplementation

Objective of this study was to assess the quantification of osteocalcin (OCN) expression by ovine osteoblasts cultured with different concentrations of sodium fluoride (F) and sodium selenite (Se) to evaluate the interaction of these agents on OCN expression in vitro . We wanted to demonstrate a possible protective effect of selenium on the toxic effect of fluoride. Osteoblasts were isolated by complete trypsin and collagenase digestion from ovine calvarial bone and cultured in DMEM supplemented with 15% FBS at 37 degrees C in a humidified 5% CO 2 incubator. Identified osteoblasts were divided into one control group (C) and eight experimental groups, which were exposed to different concentrations of sodium fluoride (F; 0, 0.5, 1 mM) sodium selenite (Se; 0, 0.1, 1 microM). At different time points after treatment total RNA was extracted and reverse transcribed into first-strand cDNA. OCN mRNA was indirectly measured by real-time fluorescent quantitative PCR (qPCR). OCN mRNA expression in F 1 mM with Se 1 microM group was found to have a high peak at day seven and was lower before and afterwards. Expression of OCN mRNA in all groups except control could be promoted by F and/or Se showing a general upregulation. Furthermore, the toxicity from excessive exposure of osteoblast with F could be circumvented by usage of moderate concentration of Se. Osteoblasts cultured in vitro may have stressful responses to F and Se at the first few days. Low concentrations of Se inhibit the toxic effects of high concentrations of F. Therefore, F and Se could be used as antagonistic factors, which could regulate osteocalcin expression.