Preparation and activities of selenium polysaccharide from plant such as Grifola frondosa.

Selenium polysaccharide is an organic selenium compound formed by the combination of polysaccharide and selenium. The biological activity of selenium polysaccharide from plant such as Grifola frondosa is generally higher than that of selenium and polysaccharide, and it is more easily absorbed and utilized by human body. Therefore, selenium polysaccharide has a wide range of applications in immune regulation, anti-tumor, anti-oxidation, anti-aging and so on. Due to the unique pharmacological activity of selenium polysaccharide, the research of selenium polysaccharide has gradually become a hot spot. At present, there are few kinds of selenium polysaccharide, but its structure is very complex. The chemical structure and mechanism of selenium polysaccharide in vivo are not completely clear and need further study. Herein, the preparation and biological activities of selenium polysaccharides were introduced systematically, which provided theoretical basis for further research and application of selenium polysaccharides.

Ebselen as template for stabilization of A4V mutant dimer for motor neuron disease therapy.

Mutations to the gene encoding superoxide dismutase-1 (SOD1) were the first genetic elements discovered that cause motor neuron disease (MND). These mutations result in compromised SOD1 dimer stability, with one of the severest and most common mutations Ala4Val (A4V) displaying a propensity to monomerise and aggregate leading to neuronal death. We show that the clinically used ebselen and related analogues promote thermal stability of A4V SOD1 when binding to Cys111 only. We have developed a A4V SOD1 differential scanning fluorescence-based assay on a C6S mutation background that is effective in assessing suitability of compounds. Crystallographic data show that the selenium atom of these compounds binds covalently to A4V SOD1 at Cys111 at the dimer interface, resulting in stabilisation. This together with chemical amenability for hit expansion of ebselen and its on-target SOD1 pharmacological chaperone activity holds remarkable promise for structure-based therapeutics for MND using ebselen as a template.

Repurposing existing drugs: identification of irreversible IMPDH inhibitors by high-throughput screening.

Inosine 5'-monophosphate dehydrogenase (IMPDH) is an essential enzyme for the production of guanine nucleotides. Disruption of IMPDH activity has been explored as a therapeutic strategy for numerous purposes, such as for anticancer, immunosuppression, antiviral, and antimicrobial therapy. In the present study, we established a luciferase-based high-throughput screening system to identify IMPDH inhibitors from our chemical library of known bioactive small molecules. The screening of 1400 compounds resulted in the discovery of three irreversible inhibitors: disulfiram, bronopol, and ebselen. Each compound has a distinct chemical moiety that differs from other reported IMPDH inhibitors. Further evaluation revealed that these compounds are potent inhibitors of IMPDHs with kon values of 0.7 × 104 to 9.3 × 104 M-1·s-1. Both disulfiram and bronopol exerted similar degree of inhibition to protozoan and mammalian IMPDHs. Ebselen showed an intriguing difference in mode of inhibition for different IMPDHs, with reversible and irreversible inhibition to each Cryptosporidium parvum IMPDH and human IMPDH type II, respectively. In the preliminary efficacy experiment against cryptosporidiosis in severe combined immunodeficiency (SCID) mouse, a decrease in the number of oocyst shed was observed upon the oral administration of disulfiram and bronopol, providing an early clinical proof-of-concept for further utilization of these compounds as IMPDH inhibitors.

A combination of selenium and polysaccharides: Promising therapeutic potential.

Currently, selenium and polysaccharide combinations can be identified as three forms: natural selenium polysaccharides, synthetic selenium polysaccharides and selenium nanoparticles decorated with polysaccharides. Previous studies have indicated that these three combinations generally show better bioactivities, including immunomodulation, anti-tumour, antioxidation and glucose regulation, than those of either selenium or polysaccharides alone. Although they have not yet been developed as new drugs for clinical trials, results from previous studies have already shown their therapeutic potential for the future. In this article, we summarize our current state of understanding of the sources, preparation methods, physicochemical characteristics and bioactivities of these combinations for the discovery of novel therapeutic drugs and adjuvants.

Biosynthesis and isolation of selenoneine from genetically modified fission yeast.

Selenoneine, a naturally occurring form of selenium, is the selenium analogue of ergothioneine, a sulfur species with health relevance not only as a purported antioxidant but likely also beyond. Selenoneine has been speculated to exhibit similar effects. To study selenoneine's health properties as well as its metabolic transformation, the pure compound is required. Chemical synthesis of selenoneine, however, is challenging and biosynthetic approaches have been sought. We herein report the biosynthesis and isolation of selenoneine from genetically modified fission yeast Schizosaccharomyces pombe grown in a medium containing sodium selenate. After cell lysis and extraction with methanol, selenoneine was purified by three consecutive preparative reversed-phase HPLC steps. The product obtained at the mg level was characterised by high resolution mass spectrometry, NMR and HPLC/ICPMS. Biosynthesis was found to be a promising alternative to chemical synthesis, and should be suitable for upscaling to produce higher amounts of this important selenium species in the future.

Ionic liquid-assisted separation and determination of selenium species in food and beverage samples by liquid chromatography coupled to hydride generation atomic fluorescence spectrometry.

Different ionic liquids (ILs) were assayed as mobile phase modifiers for the separation and determination of selenite [Se(IV)], selenate [Se(VI)], selenomethionine (SeMet) and Se-methylselenocysteine (SeMeSeCys) by reversed-phase high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry (RP-HPLC-HG-AFS). The use of several ILs: 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride ([C6mim]Cl), 1-octyl-3-methylimidazolium chloride, 1-dodecyl-3-methylimidazolium bromide, 1-hexadecyl-3-methylimidazolium bromide and tributyl(methyl)phosphonium methylsulphate was evaluated. Also, the effect of pH, buffer type and IL concentration on the separation of Se species was studied. Complete separation was attained within 12min using a C8 column and a gradient performed with a mobile phase containing 0.1% (v/v) [C6mim]Cl at pH 6.0. The proposed method allows the separation of inorganic and organic Se species in a single chromatographic run, adding further benefits over already reported methods based on RP-HPLC. In addition, the influence of ILs on the AFS signals of each Se species was evaluated and a multivariate methodology was used for optimization of AFS sensitivity. The limits of detection were 0.92, 0.86, 1.41 and 1.19µgL-1 for Se(IV), Se(VI), SeMet and SeMeSeCys, respectively. The method was successfully applied for speciation analysis of Se in complex samples, such as wine, beer, yeast and garlic.

Selenium Source Impacts Protection of Porcine Jejunal Epithelial Cells from Cadmium-Induced DNA Damage, with Maximum Protection Exhibited with Yeast-Derived Selenium Compounds.

Selenium (Se) is found in inorganic and organic forms, both of which are commonly used in animal feed supplements. The aim of this study was to determine the impact of the chemical form of Se on its associated ameliorative effects on cadmium (Cd)-induced DNA damage in a porcine model. At a cellular level, Cd mediates free oxygen radical production leading in particular to DNA damage, with consequential mutagenesis and inhibition of DNA replication. In this study, porcine jejunal epithelial cells (IPEC-J2) were pre-incubated for 48 h with one of Se-yeast (Sel-Plex), selenomethionine (Se-M), sodium selenite (Se-Ni) or sodium selenate (Se-Na). The effects of this supplementation on cell viability and DNA damage following cadmium chloride (CdCl2) exposure were subsequently evaluated. IPEC-J2 cells were cultivated throughout in medium supplemented with porcine serum to generate a superior model that recapitulated the porcine gut epithelium. The results illustrated that Se antioxidant effects were both composition- and dose-dependent as evident from cell viability (Alamar Blue and 5-carboxyfluorescein diacetate acetoxymethyl ester) and DNA damage assays (Comet and TUNEL). Both the Se-yeast and Se-M organic species, when used at the European Food Safety Authority guideline levels, had a protective effect against Cd-induced DNA damage in the IPEC-J2 model system whereas for inorganic Se-Ni and Se-Na sources no protective effects were observed and in fact these were shown to enhance the negative effects of Cd-induced DNA damage. It can be concluded that nutritional supplementation with organoselenium may protect porcine gut integrity from damage induced by Cd.

Optimization of Mycelia Selenium Polysaccharide Extraction from Agrocybe cylindracea SL-02 and Assessment of their Antioxidant and Anti-Ageing Activities.

The aim of the present study was to optimize the purification of mycelia selenium polysaccharides (MSPS) from Agrocybe cylindracea SL-02 and characterize their in vitro antioxidant and in vivo anti-ageing activities. The Box-Behnken experimental design (BBD) was evaluated, which showed that the optimum conditions included an extraction temperature of 94.99°C, a pH of 9 and a precipitation temperature of 12°C, and the predicted yield was 11.036 ± 0.31%. The in vitro antioxidant assay demonstrated that MSPS had potential effects on scavenging and enhanced the reducing power of reactive oxygen species. The in vivo anti-ageing evaluation showed that MSPS significantly reduced the malonaldehyde (MDA) contents and total cholesterol (CHOL) levels, and remarkably improved the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) in mice in response to D-galactose-induced ageing. Furthermore, the characteristic analysis of MSPS indicated a selenium content of 1.76 ± 0.10 mg/g at a concentration of 6 µg/mL in liquid media and a monosaccharide composition of rhamnose, arabinose, mannose, glucose and galactose at a molar ratio of 29:3:1:18.8:2.7. These results suggest that MSPS might be suitable for functional foods and natural drugs on preventing the ageing progress induced by toxic chemicals.

Biosynthesis of selenium rich exopolysaccharide (Se-EPS) by Pseudomonas PT-8 and characterization of its antioxidant activities.

Biosynthesis of organo-selenium is achieved by submerged fermentation of selenium-tolerant Pseudomonas PT-8. The end product of metabolic process is selenium-bearing exopolysaccharide (Se-EPS), which contains a higher content of uronic acid than the exopolysaccharide (EPS) by the strain without selenium in the culture medium. Selenium content in Se-EPS reached a maximum yield of 256.7 mg/kg when using an optimized culture condition. Crude Se-EPS was purified into two fractions-a pH neutral Se-EPS-1 and an acidic Se-EPS-2. Structure and chemical composition of Se-EPS-2 were investigated by chromatographic analyses. Results showed that Se-EPS-2 was a homogenous polysaccharide with molecular weight of 7.3 kDa, consisting of monosaccharides, rhamnose, arabinose, xylose, mannose, glucose and galactose with a molar ratio of 19.58:19.28:5.97:18.99:23.70:12.48, respectively. Compared to the EPS, the content of rhamnose in Se-EPS increased and molecular weight decreased. The Se-EPS had strong scavenging actions on DPPH•, •OH and •O2(-), which is much higher than the EPS.

The response of broccoli (Brassica oleracea convar. italica) varieties on foliar application of selenium: uptake, translocation, and speciation.

A model small-scale field experiment was set up to investigate selenium (Se) uptake by four different varieties of broccoli plants, as well as the effect of Se foliar application on the uptake of essential elements for plants calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), phosphorus (P), sulfur (S), and zinc (Zn). Foliar application of sodium selenate (Na2SeO4) was carried out at two rates (25 and 50 g Se/ha), and an untreated control variant was included. Analyses of individual parts of broccoli were performed, whereby it was found that Se in the plant accumulates mainly in the flower heads and slightly less in the leaves, stems, and roots, regardless of the Se rate and broccoli variety. In most cases, there was a statistically significant increase of Se content in all parts of the plant, while there was no confirmed systematic influence of the addition of Se on the changing intake of other monitored elements. Selenization of broccoli leads to an effective increase in the Se content at a rate of 25 g/ha, whereas the higher rate did not result in a substantial increase of Se content compared to the lower rate in all varieties. Therefore, the rate of 25 g/ha can be recommended as effective to produce broccoli with an increased Se content suitable for consumption. Moreover, Se application resulted in an adequate increase of the main organic compounds of Se, such as selenocystine (SeCys2), selenomethionine (SeMet), and Se-methylselenocysteine (Se-MeSeCys).

Purification and identification of Se-containing antioxidative peptides from enzymatic hydrolysates of Se-enriched brown rice protein.

As a further study of Se-containing proteins (Se-Pro) derived from Se-enriched brown rice (Se-BR), this paper aimed to purify and identify Se-containing antioxidative peptides (Se-antioxi-Peps) from Se-Pro hydrolysates. The total Se content in Se-BR was 6.26µg/g DW, and selenocystine, Se-methylselenocysteine, and selenomethionine were identified as the main organic Se species by high-performance liquid chromatography-inductively coupled plasma mass spectrometry. Se-Pro was extracted and hydrolyzed by four types of proteases, and Alcalase was chosen as the optimum enzyme according to the degree of hydrolysis (DH). The hydrolysate with 17.08% DH possessing the highest DPPH radical scavenging activity was separated into five fractions (F1 to F5). Fractions F3 to F5, which had high antioxidative activities, were further separated. Sub-fractions F3-3, F4-2, and F5-1 were chosen to evaluate antioxidative activities and analyze Se species. The Se-antioxi-Pep with the sequence SeMet-Pro-Ser was identified by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.

Selenoglycoproteins attenuate adhesion of tumor cells to the brain microvascular endothelium via a process involving NF-κB activation.

Selenium-containing compounds and selenized yeast have anticancer properties. In order to address possible mechanisms involved in these effects, selenoglycoproteins (SGPs) were extracted from selenium-enriched yeast at pH 4.0 and 6.5 (the fractions are called SGP40 and SGP65, respectively), followed by evaluation of their impact on the interactions of lung and breast tumor cells with human brain microvascular endothelial cells (HBMECs). Extracted SGPs, especially SGP40, significantly inhibited adhesion of tumor cells to HBMECs and their transendothelial migration. Because the active components of SGPs are unknown, small selenium-containing compounds [leucyl-valyl-selenomethionyl-arginine (LVSe-MR) and methylselenoadenosine (M-Se-A)], which are normally present in selenized yeast, were introduced as additional treatment groups. Treatment of HBMECs with SGP40, LVSe-MR and M-Se-A induced changes in gene signatures, which suggested a central involvement of nuclear factor (NF)-κB-dependent pathway. These observations were confirmed in the subsequent analysis of NF-κB DNA binding activity, quantitative measurements of the expression of selected genes and proteins, and tumor cell adhesion assay with a specific NF-κB inhibitor as the additional treatment factor. These findings indicate that specific organic selenium-containing compounds have the ability to inhibit tumor cell adhesion to brain endothelial cells via down-regulation of NF-κB. SGPs appear to be more effective than small selenium-containing compounds, suggesting the role of not only selenium but also the glycoprotein component in the observed protective impact.

Tumoricidal effects of a selenium (Se)-polysaccharide from Ziyang green tea on human osteosarcoma U-2 OS cells.

Selenium(Se)-enriched green tea consumption in human diets is well-known to reduce the risk of a variety of diseases. Here, we isolated a Se-polysaccharide (Se-ZYTP) from Se-enriched Ziyang green tea and investigated its antitumor activity on human osteosarcoma U-2 OS cells in vitro and in vivo. Se-ZYTP contained 94.5% of carbohydrate and 2.1% of uronic acid, as well as 2.14 µg/g Se, revealing that Se-ZYTP was an acidic Se-conjugated polysaccharide. Monosaccharide composition analysis indicated that Se-ZYTP consisted of mannose, rhamnose and fucose in molar ratios of 2.4:1.5:1.2:0.2:0.1:0.3:0.3. In vitro, both MTT and LTH assays proved that Se-ZYTP (25, 50, 100 and 200 µg/ml) could significantly inhibit the proliferation of human osteosarcoma U-2 OS cells in a concentration-dependent fashion (P<0.05 or P<0.01). In U-2 OS cancer xenograft model in BALB/c athymic mice, Se-ZYTP oral administration at three doses of 100, 200 and 400mg/kg body weight (B.W.) daily for 28 days resulted in obvious tumor regression as compared to model control (P<0.05 or P<0.01). In addition, body weights of mice in control or Se-ZYTP treated groups did not differ significantly and no mice died during experiment, suggesting the safety of Se-ZYTP. Therefore, we postulate that Se-ZYTP might have cancer-preventive and cancer-therapeutic benefit for human osteosarcoma.

Head space solid phase microextraction based on nano-structured lead dioxide: application to the speciation of volatile organoselenium in environmental and biological samples.

A novel and efficient speciation method based on the nano-structured lead dioxide as stationary phase of head space solid phase microextraction combined with gas chromatography mass spectrometry (GC-MS) was developed for the determination of volatile organoselenium compounds (dimethylselenide (DMSe) and dimethyldiselenide (DMDSe)) in different biological and environmental samples. PbO(2) particles with a diameter in the range of 50-70 nm have been grown on platinum wire via elechtrochemical deposition. The effect of different variables on the extraction efficiency was studied simultaneously using an experimental design. The variables of interest in the HS-SPME were condition of coating preparation, desorption time, stirring rate, desorption temperature, ionic strength, time and temperature of extraction. A Plackett-Burman design was performed for screening in order to determine the significant variables affecting the extraction efficiency. Then, the significant factors were optimized by a Box-Behnken design (BBD) and the response surface equations were derived. The detection limit and relative standard deviation (RSD) (n=5, c=50 µgL(-1)) for DMSe were 16 ngL(-1) and 4.3%, respectively. They were also obtained for DMDSe as 11ngL(-1) and 4.6%, respectively. The developed technique was found to be applicable to spiked environmental and biological samples.

Characterization of selenium species in extract from Niboshi (a processed Japanese anchovy).

Fish are selenium rich foodstuffs and a major selenium source for the Japanese population. Niboshi is processed from Japanese anchovy (Engraulis japonicus) and commonly used to prepare soup stock for Japanese dishes. In this study, we characterized selenium species in the Niboshi extract by ultrafiltration, ion-exchange chromatography and mass spectrometry. Selenium species in the Niboshi were more extractable by polar solvents (water and ethanol) than an apolar one (hexane) along with amino acids and proteinous species. Selenium in the water-extract from the Niboshi was mostly ascribed to organoselenium compounds with a molecular mass less than 5 kDa. Although selenoamino acids and selenoproteins and their fragments were involved in the extract, a large portion of the selenium species appeared to be low-molecular-mass organoselenium compounds other than selenoamino acids and their derivatives. Ion-exchange chromatographic separations revealed that most of the selenium species in the extract possess anionic and/or amphoteric characteristics. One of these selenium species from the Niboshi extract was detected at m/z 577 for 80Se by mass spectrometry subsequent to ion-pair extraction.

Prediction of the lipophilicity of nine new synthesized selenazoly and three aroyl-hydrazinoselenazoles derivatives by reversed-phase high performance thin-layer chromatography.

Using reversed-phase high-performance thin-layer chromatography and a methanol-water mixture as the mobile phase, the lipophilicity of 12 new synthesized derivatives is studied. The first eight compounds have as a basic chemical structure aryliden-hydrazino-selenazoles, and the second group of the three compounds belongs to aroyl-hydrazinoselenazoles. The linear correlation between R(Mw) and the methanol-water ratios showed high values for the correlation coefficient. The chromatographic hydrophobic index is determined by using the ratio -R(Mw)/S, and the obtained values ranged between 99 and 73. A good linear correlation is obtained between R(Mw) and the slope. The log P values are calculated using ACD/Labs Software. The matrices are formed with R(Mw) and log P and are subjected to a principal component analysis (PCA). The best way to extract information from PCA is graphically, by plotting the obtained matrices. By analyzing the scores, the compounds can be grouped as follows: a group containing nine compounds, and a second one containing three compounds. Each group of compounds has the same basic chemical structure.

Comparison of selenoneine found in marine organisms with selenite in the interaction with mercury compounds in vitro.

Selenium (Se) is an essential micronutrient because it forms the active center of selenoenzymes/selenoproteins in the form of selenocysteine. Another biological significance of Se is that it detoxifies inorganic mercury (iHg) by directly interacting with it. Recently, a novel selenometabolite, selenoneine (2-selenyl-N,N,N-trimethyl-L-histidine), was identified in several marine animals. However, its biological significance is still unclear. In this study, the ability of selenoneine to form a complex with iHg and methyl Hg (MeHg) was evaluated in vitro. Whereas selenite serving as the positive control reacted with iHg by direct interaction after being converted into selenide by endogenous reductants, such as glutathione (GSH), selenoneine did not interact with iHg or MeHg in the liver homogenate of marine turtle. This indicates that selenoneine may not play a role in the detoxification of Hg.

[Determination of selenium species in food by high performance liquid chromatography with inductively coupled plasma mass spectrometry].

An analytical method for selenium species of selenate (SeVI), selenite (SeIV), selenomethionine (SeMet), selenocystine (SeCys2 ) and selenoethionine (SeEt) was established using high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A Hamilton PRP X-100 reversed-phase anion exchange column (250 mm x 4.6 mm, 5 microm) with a 5 mmol/L citric acid buffer solution (pH 4.5, adjusted with 20% (v/ v) ammonia) as mobile phase was used for separation, and ICP-MS was used for detection. The five species were completely separated within 21 min. All the linear correlation coefficients of the five selenium species were greater than 0.999 5, and the detection limits of SeVI, SeIV, SeMet, SeCys2, SeEt were 0.4, 0.4, 5.6, 0.9 and 1.2 microg/L, respectively. The extraction procedure was studied for fresh mushroom and pork samples. For water-soluble selenium compounds, citric acid was a good extraction solution, and the recoveries were around 100% for inorganic selenium and in the range of 85.0% - 95.3% for SeMet; but worse for SeCys2 and SeEt. As for the proteinase K, the recoveries of SeCys2 and SeEt were raised to the range of 79.9% -91.5%. The method has the advantages of simple operation and good accuracy, and can be used for the quantitative determination of the five selenium species in food.

Headspace hollow fiber protected liquid-phase microextraction combined with gas chromatography-mass spectroscopy for speciation and determination of volatile organic compounds of selenium in environmental and biological samples.

A simple and novel speciation method for the determination of volatile organic compounds of selenium (dimethylselenide (DMSe) and dimethyldiselenide (DMDSe) has been developed using a headspace hollow fiber protected liquid-phase microextraction (HS-HF-LPME) combined with capillary gas chromatography-mass spectrometry (GC-MS). The organic solvent impregnated in the pores and filled inside the porous hollow fiber membrane was used as an extraction interface in the HS-HF-LPME of the compounds. The effect of different variables on the extraction efficiency was studied simultaneously using an experimental design. The variables of interest in the HS-HF-LPME were sample volume, extraction time, temperature of sample solution, ionic strength, stirring rate and dwelling time. A Plackett-Burman design was performed for screening in order to determine the significant variables affecting the extraction efficiency. Then, the significant factors were optimized by a Box-Behnken design (BBD) and the response surface equations were derived. Under optimum conditions, preconcentration factors up to 1250 and 1170 were achieved for DMSe and DMDSe respectively. The detection limit and relative standard deviation (RSD) (n=5, c=50 µg L(-1)) for DMSe were 65 ng L(-1) and 4.8%, respectively. They were also obtained for DMDSe as 57 ng L(-1) and 3.9%, respectively. The developed technique was found to be applicable to spiked environmental and biological samples.

Production of dimethyl triselenide and dimethyl diselenenyl sulfide in the headspace of metalloid-resistant Bacillus species grown in the presence of selenium oxyanions.

A Bacillus species harvested from the environment is metalloid resistant and, when grown anaerobically in complex growth medium and amended with the selenium oxyanion selenate, selenite, or selenocyanate, produces volatile organoselenium compounds in bacterial culture headspace. Two novel compounds so far undetected in bacterial culture headspace, CH3Se2SCH3 and CH3SeSeSeCH3, are produced and can be detected using solid-phase microextraction and gas chromatography with either fluorine-induced chemiluminescence or mass spectrometric detection. Differences in the electron impact fragmentation pattern of the mixed sulfur/selenide compounds allow the tentative differentiation between the symmetric and asymmetric isomers in this bacterium's headspace in favor of the asymmetric CH3SeSeSCH3 isomer.