A method was developed for the simultaneous determination of selenomethionine (SeMet) and selenocysteine (SeCys) in meat (chicken and lamb muscles) and different offal tissues (heart, liver, kidney). The analytical procedure was based on the protein extraction with urea under reducing conditions (dithiothreitol), derivatization of SeCys and SeMet by carbamidomethylation with iodoacetamide (IAM) followed by quantitative proteolysis. The mixture of the derivatized Se-amino acids was purified by size-exclusion liquid chromatography (LC) and analysed by ion-paring reversed-phase HPLC-inductively coupled plasma mass spectroscopy (ICP MS). The quantification of SeCys and SeMet was carried out by the method of standard additions. (77)SeMet was used to control the SeMet derivatization efficiency and recovery. The method was validated by the determination of the Se mass balance. The Se-amino acids accounted for 91 +/- 8% of the total selenium (mean of 95 samples of seven tissues analysed over a period of 18 months). The method was applied to the discrimination of the contribution of selenoproteins (containing SeCys) and other Se-containing proteins (containing SeMet) in tissues of animals during supplementation studies (dose-effect and tolerance).

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Coinage metal complexes of an N,N'-disubstituted cyclic thiourea exert significant cytotoxicities to cancer cells and, in particular, the gold(i) thiourea complex exhibits a potent tight-binding inhibition of the anticancer drug target thioredoxin reductase with an inhibitory constant at nanomolar level.

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The occurrence of SeNPs in commercial Se-rich yeasts was confirmed by SP-ICPMS for the first time.

Several novel selenium containing compounds were characterized in staple crops (wheat, rice and maize) grown on soils naturally rich in selenium. A dedicated method based on the coupling of liquid chromatography with multiplexed detection (ICP-MS, ESI-Orbitrap MS(/MS)) was developed for the speciation of low-molecular weight (<5 kDa) selenium metabolites. Nine species present in different proportions as a function of the crop type were identified by cation-exchange HPLC-ESI-Orbitrap MS on the basis of the accurate molecular mass and MS/MS spectra. The natural origin of these species was then validated by varying extraction conditions and by using hydrophilic interaction LC (HILIC)-ESI-Orbitrap MS(/MS). Among the identified compounds, Se-containing monosaccharides (hexose moiety, m/z 317 and m/z 358) or Se-containing disaccharides (hexose-pentose moiety, m/z 407 and m/z 408) were the first selenosugars reported in edible plants. It is also the first report of the presence of 2,3-dihydroxypropionyl-selenolanthionine (m/z 345) in rice. Because these crops can be an important source of selenium in animal and human nutrition, the understanding of the origin and the fate of these species during metabolic processes will be of great interest.

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A method for the simultaneous determination of selenomethionine (SeMet), selenocysteine (SeCys), and selenite [Se(IV)] in chicken eggs was developed. A sample preparation protocol including defatting, protein denaturation, and carbamidomethylation was optimized in order to achieve complete protein digestion and to avoid SeCys losses. Quantification was carried out by reversed-phase HPLC-inductively coupled plasma mass spectrometry (ICP MS) after quantitative isolation of the selenium-containing fraction by size-exclusion liquid chromatography. The detection limits were 0.06, 0.003, and 0.01 microg g(-1) (dry weight) for SeCys, Se(IV) and SeMet, respectively, and the precision was 5-10%. The end products of carbamidomethylation of the different selenium species were identified for the first time by electrospray QTOF MS after custom-designed 2D HPLC purification. Differences in selenium speciation in egg yolk and white were highlighted, the yolk containing more SeCys and the white more SeMet. An insight into selenium bioaccessibility in eggs was obtained by digestion with simulated gastric and gastrointestinal juices and size-exclusion HPLC-ICP MS.