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Results for “Selenium Compounds”

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At least 649 records · Page 36Linked to original sources
PubMed1990

Interactions of selenium and fluoride on growth, glycolysis and survival of Streptococcus mutans GS-5.

The effects of low concentrations (1.0 mmol/l of selenite and seleno-dl-cystine were tested alone, or in combination with NaF, on growth, glycolysis, and survival of Streptococcus mutans GS-5. In batch culture, both selenium-containing compounds (1.0 mmol/l) inhibited the growth rate and final cell yield by 92% or greater; glycolysis, however, was not affected. The observed bactericidal action of selenite at 0.1 mmol/l was pH-dependent. Fluoride reduced the killing effect of SeO3 in the culture medium and in a lactate-acetate buffer system at pH 6.5, 5.0 and 4.0. These data indicate that selenium-containing compounds exert an antibacterial action on cells of S. mutans in a manner which leaves glycolysis unaffected.

Animals↗
PubMed2004

Chemoprevention of prostate cancer with selenium: an update on current clinical trials and preclinical findings.

Prostate cancer is the most common cancer diagnosed and the second leading cause of cancer-related deaths in men in the United States. The etiological factors that give rise to prostate cancer are not known. Therefore, it is not possible to develop primary intervention strategies to remove the causative agents from the environment. However, secondary intervention strategies with selenium (Se) compounds and other agents represent a viable option to reduce the morbidity and mortality of prostate cancer. In this review, we discuss ongoing clinical trials. In addition, we discuss preclinical mechanistic studies that provide insights into the biochemical and molecular basis for the anti-carcinogenic activity of both inorganic and organic forms of Se.

Clinical Trials as Topic↗
PubMed2006

Activation energies of selenoxide elimination from Se-substituted selenocysteine.

Transition states for selenoxide elimination have been determined for a series of Se-substituted selenocysteine (RSeCys) derivatives that have potential use in the prevention and treatment of cancer, either directly or in conjunction with cisplatin (to reduce its nephrotoxic effects). Reduced activation barriers vs R=Me and R=Ph are found when the alkyl chain length is increased or when activating groups are para to the selenide. Ortho substitution of Lewis bases stabilizes the transition state by directly donating electron density to the selenoxide. The results suggest that RSeCys derivatives incorporating the properties of glutathione peroxidase mimics will, upon oxidation, rapidly eliminate selenenic acid, a precursor to chemopreventative selenols.

Electrons↗
PubMed1996

Use of INAA to study the interaction between Se and Te in cells of Saccharomyces cerevisiae.

The differences in the effects of inorganic Se (IV and VI) compounds and seleno-cystine [(CySe)2] on the Te (as Na2TeO3) uptake by the yeast, Saccharomyces cerevisiae, has been studied. Se, Te, Ag, Zn, Fe and Co contents of the cells were measured by instrumental neutron activation analysis. For the determination of the Ag content, the monostandard method was applied as the analytical method. The contents of other elements were determined by comparison with standards having similar amounts of the determined element as the sample. Results obtained show that an antagonist interaction occurs between SeO2 and Te. There was a significant increase in the concentrations of Se and Te when the yeast was incubated in the medium containing (CySe)2 and Te. (CySe)2 markedly increased the Ag content of cells, especially within the first 8 h of incubation. The low level of SeO2 in the medium are the exterior factor which produce an observable increase of the Ag concentration in the cells. The higher level of SeO2 in the medium causes a long-term marked increase in the Ag content of the cells. The uptake yield of Ag also increased in the presence of (NH4)2SeO4 in the medium. The Te supply produced a significant enhancement in the Ag content of the cells during the initial 8 h of incubation. The presence of Se and/or Te in the medium causes change in the intracellular Zn, Fe and Co levels.

Cystine↗
PubMed2002

Formation of vesicle-templated CdSe hollow spheres in an ultrasound-induced anionic surfactant solution.

Hollow sphere of CdSe with size of approximately 100-200 nm can be templated from anionic surfactant sodium dodecyl sulfate (SDS) vesicles induced by the ultrasonic irradiation. The successful vesicle templating indicated that the outer leaflet of the bilayer is the receptive surface in the controlled growth of CdSe nanoparticles, which provide the unique reactor for the nucleation and mineralization growth of CdSe nanoparticles. The products were characterized by XRD, TEM, and HRTEM techniques. UV-vis spectrum recorded the optical properties of CdSe hollow spheres (2.01 eV), which showed an obvious blue shift relative to the bulk cubic CdSe (1.73 eV). Surfactant molecules (SDS) passivated in the CdSe hollow spheres were completely extracted, as determined by thermal gravimetric analysis (TGA). Systematic studies found that the ultrasound irradiation and concentration of surfactant (SDS) in the system were important factors on the controlled synthesis desired hollow sphere morphologies, and also the temperance have an importance influence on the mineralization and crystallization of the CdSe hollow spheres. Based on the observation on morphological difference of CdSe in different systems, the possible mechanism for the formation of CdSe hollow spheres was discussed.

Cadmium Compounds↗
PubMed2006

Spectroscopic and quantum chemical study of the novel compound cyclopropylmethylselenol.

An investigation into the properties of the novel compound cyclopropylmethylselenol has been undertaken by use of Stark-modulation microwave spectroscopy and high-level quantum chemical calculations. Ground-state spectra belonging to six isotopomers of a single conformer of the molecule were recorded and assigned. This conformer, predicted to be the lowest in energy by a series of quantum chemical calculations, possesses a synclinal arrangement of the H-C-C-Se atoms. In addition to the assignment of these ground-state spectra, transitions attributable to vibrationally excited states of the 78Se- and 80Se-containing isotopomers were identified. A tentative assignment of these excited-state spectra to specific vibrational modes has been made with the assistance of a density functional theory calculation at the B3LYP/6-311++G(3df,2pd) level of theory. Close agreement was found between experimental ground-state rotational constants and ab initio equilibrium values calculated at the MP2/aug-cc-pVTZ level of theory. Good agreement was also noted between certain r(s) principal axis coordinates of atoms in the molecule and the corresponding ab initio r(e) values. Limited evidence in favor of the formation of a weak intramolecular hydrogen bond between the H atom of the selenol group and electron density associated with the cyclopropyl ring is discussed.

Algorithms↗
PubMed2006

Highly luminescent, stable, and water-soluble CdSe/CdS core-shell dendron nanocrystals with carboxylate anchoring groups.

A dendron ligand with two carboxylate anchoring groups at its focal point and eight hydroxyl groups as its terminal groups was found to efficiently convert as-synthesized CdSe/CdS core-shell nanocrystals in toluene to water-soluble dendron-ligand stabilized nanocrystals (dendron nanocrystals). The resulting dendron nanocrystals retained 60% of the photoluminescence value of the original CdSe/CdS core-shell nanocrystals in toluene and were significantly brighter than the similar dendron nanocrystals with thiolate (deprotonated thiol group) as the anchoring group which retained just 10% of the photoluminescence value of the original CdSe/CdS core-shell nanocrystals in toluene. The carboxylate-based dendron nanocrystals survived UV irradiation in air for at least 13 days, about 9 times better than the thiolate-based dendron nanocrystals (35 h) and similar to that of the thiolate-based dendron-box stabilized CdSe/CdS core-shell nanocrystals (box nanocrystals). Upon UV irradiation, the dendron nanocrystals became even 2 times brighter than the original CdSe/CdS core-shell nanocrystals in toluene, and the UV-brightened PL can retain the brightness for at least several months. These stable and bright dendron nanocrystals were soluble in various aqueous media, including all common biological buffer solutions tested, for at least 1.5 years. In addition to their superior performance, the synthetic chemistry of carboxylate dendron ligands and the corresponding dendron nanocrystals is relatively simple and with high yield.

Cadmium Compounds↗
PubMed2002

Speciation of seleno compounds in yeast aqueous extracts by three-dimensional liquid chromatography with inductively coupled plasma mass spectrometric and electrospray mass spectrometric detection.

A three-dimensional liquid chromatographic purification protocol based on sequential size-exclusion, anion-exchange and cation-exchange separation mechanisms was developed for the mapping of seleno compounds in aqueous yeast extracts. The method allowed the demonstration of the presence of more than 30 different seleno compounds. Semi-preparative size-exclusion and anion-exchange chromatography were optimized for maximum resolution using electrospray-compatible buffers in order to purify the compounds for mass spectrometric analysis. Molecular masses were attributed to many of the compounds on the basis of the selenium isotopic pattern in the electrospray mass spectra and of the collision-induced fragmentation patterns. Limitations preventing the ultimate identification of the selenium species detected are discussed.

Chromatography, Liquid↗
PubMed2006

Improved efficiency of photovoltaics based on CdSe nanorods and poly(3-hexylthiophene) nanofibers.

We present photovoltaic devices based on a blend of the conjugated polymer poly(3-hexylthiophene) (P3HT) with cadmium selenide nanorods, where the solvent for film deposition has been carefully chosen to optimize the film morphology. Using 1,2,4-trichlorobenzene (TCB), which has a high boiling point, as solvent for P3HT it is possible to obtain a fibrilar morphology, providing extended pathways for hole transport. Blend devices fabricated using this solvent gave solar power conversion efficiencies of 2.6%. This indicates that efficient transport of electrons and holes is achieved in these films, allowing them to operate effectively at solar illumination intensities.

Cadmium Compounds↗
PubMed2004

Antinociceptive profile of 2-phenylselenenyl-1,8-cineole in mice.

2-Phenylselenenyl-1,8-cineole (PSC) increased both the pentobarbital-induced sleeping time and the reaction time (up to 2 h) in the tail immersion method. PSC also caused dose-dependent inhibition of acetic acid induced writhing with maximum inhibition of 93.4% and was approximately 8.5-fold more potent than 1,8-cineole. These findings show that PSC presents sedative effect and significant antinociceptive activity.

Analgesics↗
PubMed2006

Enantiodiscrimination by NMR spectroscopy.

The analysis of enantiorecognition processes involves the detection of enantiomeric species as well as the study of chiral discrimination mechanisms. In both fields Nuclear Magnetic Resonance (NMR) spectroscopy plays a fundamental role, providing several tools, based on the use of suitable chiral auxiliaries, for observing distinct signals of enantiomers and for investigating the complexation phenomena involved in enantiodiscrimination processes.

Data Interpretation, Statistical↗