On the nature of selenium toxicity and carcinostatic activity

Spallholz, Julian E.

doi:10.1016/0891-5849(94)90007-8

Cited by 561 publications

(349 citation statements)

References 66 publications

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“…In contrast, reports are available on the potentially detrimental effects of inorganic Se sources such as selenite (Mahan et al, 1999). The oxidation of thiols like glutathione by selenite and other Se compounds can produce superoxide or H 2 O 2 (Spallholz, 1994). So even though we did not see negative changes of SOD or TBARS in liver and the nonstored abdominal muscle, prooxidative traits of inorganic Se might only be brought about in a prooxidative environment such as during retail display.…”

Section: Retail Displaycontrasting

confidence: 69%

Influence of high inorganic selenium and manganese diets for fattening pigs on oxidative stability and pork quality parameters

Schwarz

Ebner

Furtner

et al. 2017

Animal

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Data are scarce regarding combined high Se and Mn supplementation in livestock diets, however, as Se and Mn are functionally related as cofactors of glutathione peroxidase (GPx) and Mn-superoxide dismutase (SOD), respectively, beneficial synergistic effects on oxidative stability of tissues may result. This experiment evaluated the effect of an oversupply of Se and Mn within European legal limits compared with recommendations on performance, oxidative stability of the organism and meat quality in a randomised complete block design. A total of 60 crossbred gilts were fed maize-barley-soya bean meal diets formulated in a 2 × 2 factorial approach with inorganic Se (0.2 v. 0.5 mg/kg Se dry matter (DM)) or inorganic Mn (20 v. 150 mg/kg Mn DM) from 31 to 116 kg BW. Se supplementation reduced feed intake, whereas high Mn diets impaired average daily gain ( P < 0.05). Qualitative carcass characteristics were impaired by Se and Mn predominantly in the semimembranosus muscle. Activity of GPx in liver was increased by high Se diets ( P < 0.05). Mn supplementation increased catalase (CAT) activity in liver, GPx in plasma and total antioxidative capacity (TAC) in muscle, whereas it decreased CAT activity in plasma ( P < 0.05). Cu/Zn-SOD in muscle showed higher activity in high-Se-low-Mn diets but lower activity when both high Se and Mn were combined (Se × Mn P < 0.05). Mn supplementation increased Mn concentration in longissimus thoracis et lumborum, but simultaneously reduced Se concentration ( P < 0.05). Upon retail display, Mn increased lipid oxidation more pronouncedly (higher thiobarbituric acid reactive substances; P < 0.05) than Se ( P < 0.10). Despite some positive effects (Mn increased TAC, Se increased GPx, Se and Mn increased tenderness), no synergistic effects of high Se and Mn diets or an overall beneficial impact on meat quality, especially during storage, could be observed. Including the negative effects on performance, feeding Se and Mn up to the maximum legal level cannot be recommended.

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Section: Retail Displaycontrasting

confidence: 69%

Influence of high inorganic selenium and manganese diets for fattening pigs on oxidative stability and pork quality parameters

Schwarz

Ebner

Furtner

et al. 2017

Animal

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“…Whereas MSeA reacts with GSH to deliver CH 3 SeH directly to cells (22), selenite undergoes thioldependent reduction via reduced GSH to H 2 Se, which is then methylated to produce CH 3 SeH (20,21). H 2 Se can also be incorporated into selenoproteins as selenocysteine or react with molecular oxygen to generate superoxide radicals (20,23,24). Our goal was to characterize the effects of selenite on AR signaling in prostate cancer cells and to determine whether selenite and MSeA shared similar molecular mechanisms of action.…”

Section: Discussionmentioning

confidence: 99%

“…Glutathione (GSH) is the main intracellular thiolbased antioxidant and high doses of selenite not only consume total GSH but also generate superoxide radicals (20,23,24). Alterations in the intracellular redox state can affect the activity of redox-sensitive proteins via the oxidation of critical cysteine residues, which may in turn have downstream effects on signal transduction and gene transcription.…”

Section: Introductionmentioning

confidence: 99%

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Inhibition of androgen receptor signaling by selenite and methylseleninic acid in prostate cancer cells: two distinct mechanisms of action

Husbeck

Bhattacharyya

Feldman

et al. 2006

Molecular Cancer Therapeutics

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The development of prostate cancer and its progression to a hormone-refractory state is highly dependent on androgen receptor (AR) expression. Recent studies have shown that the selenium-based compound methylseleninic acid (MSeA) can disrupt AR signaling in prostate cancer cells. We have found that selenite can inhibit AR expression and activity in LAPC-4 and LNCaP prostate cancer cells as well but through a different mechanism. On entering the cell, selenite consumes reduced glutathione (GSH) and generates superoxide radicals. Pretreatment with N-acetylcysteine, a GSH precursor, blocked the down-regulation of AR mRNA and protein expression by selenite and restored AR ligand binding and prostatespecific antigen expression to control levels. MSeA reacts with reduced GSH within the cell; however, Nacetylcysteine did not effect MSeA-induced downregulation of AR and prostate-specific antigen. The superoxide dismutase mimetic MnTMPyP was also found to prevent the decrease in AR expression caused by selenite but not by MSeA. A Sp1-binding site in the AR promoter is a key regulatory component for its expression. Selenite decreased Sp1 expression and activity, whereas MSeA did not. The inhibition of Sp1 by selenite was reversed in the presence of N-acetylcysteine. In conclusion, we have found that selenite and MSeA disrupt AR signaling by distinct mechanisms. The inhibition of AR expression and activity by selenite occurs via a redox mechanism involving GSH, superoxide, and Sp1.

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“…In contrast, in leg muscles, more carbonyl groups were detected after dietary modulation with selenium (for 0.26 mg kg -1 and 0.50 mg kg -1 for inorganic and organic selenium, respectively), which could be explained as a pro-oxidative action of the microelement. Hence, in high concentrations selenium compounds are toxic by their pro-oxidant catalytic activity to produce superoxide (O 2 -), hydrogen peroxide, and very likely other cascading oxyradicals [40], which can accelerate lipid and protein oxidation in meat. Three-month freezing storage resulted in a significant (p ≤ 0.05) increase in the formation of protein carbonyls in control breast and leg muscles (up to 3.0−3.5 nM g -1 protein), indicating the extent of oxidation processes in relation to fresh and chilled meat.…”

Section: Changes In Meat Protein Carbonyls After Modulation With Selementioning

confidence: 99%

Carbonyl and sulfhydryl groups of chicken meat proteins after dietary modulation with selenium

2015

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Abstract:The objective of the study was to investigate the effects of selenium modulation on the alteration of carbonyl and sulfhydryl groups in proteins in chicken breast and leg meat. Selenium, in the form of sodium selenite and selenized yeast, was applied to broiler chicken at 0.26, 0.38 and 0.50 mg Se kg -1 . The alteration of protein carbonyl and sulfhydryl groups, as well as total antioxidative potential of breast and leg meat were analyzed in fresh, chilled and frozen material. Protein reactive groups were effectively protected against oxidatively induced changes (carbonyl groups formation) by dietary selenium supplementation, during frozen storage of both types of chicken muscles, either with white fibre domination (breast) or with red fibre domination (leg). The inorganic form of selenium was effective in decreasing the loss of protein sulfhydryl groups in muscles with red fibre domination during frozen storage. In conclusion, selenium compounds can be used in broiler nutrition as a protein antioxidizing agent, especially in perspective of the long storage of meat under freezing conditions.

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On the nature of selenium toxicity and carcinostatic activity

Cited by 561 publications

References 66 publications

Influence of high inorganic selenium and manganese diets for fattening pigs on oxidative stability and pork quality parameters

Influence of high inorganic selenium and manganese diets for fattening pigs on oxidative stability and pork quality parameters

Inhibition of androgen receptor signaling by selenite and methylseleninic acid in prostate cancer cells: two distinct mechanisms of action

Carbonyl and sulfhydryl groups of chicken meat proteins after dietary modulation with selenium

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