tellurium and tellurium-tetrachloride

The regioselective synthesis of novel functionalized condensed organochalcogen compounds by chalcogenocyclofunctionalization reactions based on chalcogen halides and the natural products thymol and carvacrol has been developed. The reactions of selenium dibromide with allyl thymol and allyl carvacrol proceeded in methylene chloride at room temperature in the presence of NaHCO

Topics: Biological Products; Chalcogens; Cymenes; Selenium; Sulfur; Tellurium; Thymol

The reaction of tellurium tetrachloride with acetylene proceeds in a stereospecific anti-addition manner to afford the novel products E-2-chlorovinyltellurium trichloride and E,E-bis(2-chlorovinyl)tellurium dichloride. Reaction conditions for the selective preparation of each of these products were found. The latter was obtained in 90% yield in CHCl(3) under a pressure of acetylene of 10-15 atm, whereas the former product was formed in up to 72% yield in CCl(4) under a pressure of acetylene of 1-3 atm. Synthesis of the previously unknown E,E-bis(2-chlorovinyl) telluride, E,E-bis(2-chlorovinyl) ditelluride, E-2-chlorovinyl 1,2,2-trichloroethyl telluride and E,E-bis(2-chlorovinyl)-tellurium dibromide is described.

Topics: Acetylene; Carbon Tetrachloride; Chloroform; Hydrocarbons, Chlorinated; Magnetic Resonance Spectroscopy; Stereoisomerism; Tellurium

Diphenyl ditelluride (DPDT) and tellurium tetrachloride (TeCl(4)) were evaluated for toxicity in transformed (HT-29, Caco-2) and non-transformed colon cells (CCD-18Co). Significant decreases in viability were observed with DPDT exposure in HT-29 (62.5-1000 μM), Caco-2 (31.25-1000 μM) and CCD-18Co cells (500-1000 μM) and with TeCl(4) in HT-29 (31.25-1000 μM), Caco-2 (31.25-1000 μM) and CCD-18Co cells (500-1000 μM). Light microscopy confirmed viability analysis. Significant increases in caspase 3/7 and 9 activity were observed with DPDT in HT-29 (500-1000 μM) and CCD-18Co cells (1000 μM) indicating apoptosis. No significant increases in caspases were seen with TeCl(4) indicating necrosis. Apoptosis or necrosis was confirmed with fluorescent staining (FITC-Annexin, Hoechst 33342 and Ethidium Homodimer). Significant decreases in GSH/GSSG ratio were observed with DPDT in HT-29 (62.5-1000 μM), and CCD-18Co cells (1000 μM) and with TeCl(4) in HT-29 (62.5-1000 μM) and CCD-18Co cells (250-1000 μM). We concluded that cells treated with DPDT resulted in apoptosis and TeCl(4) treatment in necrosis. GSH/GSSG ratio shifts indicate oxidative mechanisms are involved.

Topics: Benzene Derivatives; Caco-2 Cells; Caspases; Cell Transformation, Neoplastic; Hazardous Substances; HT29 Cells; Humans; Organometallic Compounds; Tellurium

Tellurium tetrachloride (TeCl(4)) and diphenyl ditelluride (DPDT) cytotoxicity, was investigated in rat astrocytes. Concentrations of 0.24-250μM (24h) were tested for viability using MTT(3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) and trypan blue exclusion. MTT showed significant decreases at all concentrations tested for both compounds. Significant decreases in viability were seen in 1.95-250μM of DPDT and 0.97-250μM of TeCl(4) with trypan blue exclusion. The LC(50) for both compounds was 62.5μM. Light and scanning microscopy confirm toxicity observed at higher concentrations. Thiobarbituric acid reactive substances (TBARs) assay, TUNEL, cytochrome c and caspase release were carried out. No significant increase in TBARS with either agent was observed (15.625-62.5μM). TUNEL and cytochrome c assays demonstrated apoptosis in TeCl(4) treated cells (31.25-125μM). Non-apoptotic cells were observed in DPDT treated cells. Studies of caspase 3/7 and caspase 9 indicated increased activity in TeCl(4) but not in DPDT treated cells. Optical Emission Spectroscopy of DPDT and TeCl(4) treated cells demonstrated significant accumulation of elemental tellurium in all treatment groups (31.25-125μM). We conclude that DPDT and TeCl(4) are cytotoxic to astrocytes. TeCl(4) treated cells die via the intrinsic apoptotic pathway. Accumulation of tellurium occurs with both compounds, but results in different mechanisms of cell death.

Topics: Animals; Astrocytes; Benzene Derivatives; Caspases; Cell Survival; Cytochromes c; Formazans; Hippocampus; Microscopy, Electron, Scanning; Organometallic Compounds; Rats; Rats, Sprague-Dawley; Tellurium; Tetrazolium Salts; Thiobarbituric Acid Reactive Substances

Despite the growing use of organotellurium compounds in the chemical and biomedical fields, there has been no great concern about their toxicity until now. To test the possibility that diphenyl ditelluride (DPDT) and tellurium chloride (TeCl2), organic and inorganic tellurium compounds, may exert adverse action on mammals, their effects on rat thymocytes were examined under in vitro conditions using a flow cytometer with fluorescent probes. Incubation of thymocytes with DPDT at 300 nM or more for 24 h significantly increased the populations of shrunken cells and of cells with hypodiploidal DNA. Z-VAD-FMK, a paninhibitor of caspases, greatly suppressed the DPDT-induced increase in the hypodiploidal cell population, suggesting the involvement of caspase activation in DPDT toxicity. Hence, it is possible that DPDT would increase the population of thymocytes undergoing apoptosis if the blood concentration in mammals reached at least 300 nM or more. TeCl2 was much less potent than DPDT in increasing the population of hypodiploidal cells.

Topics: Animals; Apoptosis; Benzene Derivatives; Cell Culture Techniques; Cell Size; Dose-Response Relationship, Drug; Flow Cytometry; Male; Organometallic Compounds; Rats; Rats, Wistar; Tellurium; Thymus Gland

A Zn(2+)-glycerophosphocholine cholinephosphodiesterase (EC 3.1.4.38) purified from mouse brain was found to be reversibly inhibited by tellurium tetrachloride. This effect was characterized by a competitive pattern of inhibition, with apparent Ki values of 0.7 microM and 1.5 microM for the hydrolysis of p-nitrophenylphosphocholine and glycerophosphocholine respectively. Interestingly, the inhibitory effect of tellurium tetrachloride was found to be greatly potentiated by tetramethylammonium salt, indicative of a synergistic interaction between the two compounds. Additionally, it was observed that the effect of tellurium tetrachloride was not affected by a number of other metal ions, and was more pronounced at neutral pH, suggesting that the inhibitory role of the tellurium tetrachloride may be of importance under physiological conditions. Thus Zn(2+)-glycerophosphocholine cholinephosphodiesterase is proposed to be one of the target enzymes which is susceptible to the inhibitory effect of tellurium tetrachloride.

Topics: Animals; Brain; Cations, Divalent; Cell Membrane; Edetic Acid; Kinetics; Mice; Phosphodiesterase Inhibitors; Phosphoric Diester Hydrolases; Quaternary Ammonium Compounds; Selenium; Tellurium; Zinc

Seventy newly hatched ducklings were fed a commercial ration with 500 mg of added Te (as tetrachloride)/kg of feed for up to 28 days. Ducklings were euthanatized at day 14, 21, and 28, the hearts were studied by gross, microscopic, and ultrastructural examination. Cardiac damage was apparent grossly as hydropericardium and myocardial hemorrhage. Histopathologically, the ventricular myocardium had areas of acute hemorrhagic necrosis (often with mineralization), edema, and congestion. Resolving areas of necrosis appeared cellular with macrophages, heterophils, fibroblasts, and pale vacuolated cells with large vesicular nuclei that were identified as dedifferentiated myocytes. Ultrastructurally, necrotic fibers had disrupted contractile material and mineralized mitochondria. In resolving lesions, macrophages were numerous in the interstitium and within necrotic fibers. Also, a population of sublethally injured myocytes was present and appeared as dedifferentiated cardiac muscle cells with few myofibrils, scattered free filaments, prominent sarcoplasmic reticulum, abundant glycogen, and large nuclei with prominent nucleoli. These dedifferentiated myocytes represented a reparative phase of the Te-induced myocardial injury which has been termed "reactive hyperplasia" and "rejuvenating reorganization" in previous models of myocardial damage.

Topics: Animals; Diet; Ducks; Heart; Male; Microscopy, Electron; Myocardium; Necrosis; Organoids; Tellurium