Navegando por Palavras-chave "tellurium"

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    Copper Catalyzed Cross-Coupling Reactions of Diaryl Ditellurides with Potassium Aryltrifluoroborate Salts
    (Soc Brasileira Quimica, 2009-01-01) Alves, Diego; Pena, Jesus M.; Vieira, Adriano Siqueira; Botteselle, Giancarlo V.; Guadagnin, Rafael Carlos; Stefani, Helio Alexandre [UNIFESP]; Universidade de Brasília (UnB); Universidade Federal de São Paulo (UNIFESP); Univ Fed Alagoas; Ctr Desenvolvimento Tecnol Nucl
    We present here results of the cross-coupling reaction of diaryl ditellurides with potassium aryltrifluoroborate salts using a catalytic amount of Cu(OAc)(2) and bypiridine in DMSO/H(2)O under air atmosphere. This cross-coupling reaction is general and was performed with diaryl ditellurides and potassium aryltrifluoroborate salts bearing electron-withdrawing, electron-donating and neutral substituents, affording the corresponding unsymmetrical diaryl tellurides in good to excellent yields.
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    A glimpse on biological activities of tellurium compounds
    (Academia Brasileira de Ciências, 2009-09-01) Cunha, Rodrigo Luiz Oliveira Rodrigues [UNIFESP]; Gouvea, Iuri Estrada [UNIFESP]; Juliano, Luiz [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Tellurium is a rare element which has been regarded as a toxic, non-essential trace element and its biological role is not clearly established to date. Besides of that, the biological effects of elemental tellurium and some of its inorganic and organic derivatives have been studied, leading to a set of interesting and promising applications. As an example, it can be highlighted the uses of alkali-metal tellurites and tellurates in microbiology, the antioxidant effects of organotellurides and diorganoditellurides and the immunomodulatory effects of the non-toxic inorganic tellurane, named AS-101, and the plethora of its uses. Inasmuch, the nascent applications of organic telluranes (organotelluranes) as protease inhibitors and its applications in disease models are the most recent contribution to the scenario of the biological effects and applications of tellurium and its compounds discussed in this manuscript.
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    Poliovirus 3C proteinase inhibition by organotelluranes
    (Walter de Gruyter & Co, 2011-04-01) Gouvea, Iuri E. [UNIFESP]; Santos, Jorge A. N. [UNIFESP]; Burlandy, Fernanda M.; Tersariol, Ivarne L. S.; Silva, Edson E. da; Juliano, Maria A. [UNIFESP]; Juliano, Luiz [UNIFESP]; Cunha, Rodrigo L. O. R. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Inst Oswaldo Cruz; Univ Mogi das Cruzes; Universidade Federal do ABC (UFABC)
    The 3C proteinase, essential for human poliovirus (PV) replication, has unique characteristics as its three-dimensional structure resembles chymotrypsin, but its catalytic nucleophile is a cysteine SH group rather than the OH group of serine. Here, we describe the use of tellurium compounds as inhibitors of PV3C proteinase. A rapid, stoichiometric and covalent inactivation of PV3C was observed with both a chloro-telluroxetane and a bis-vinylic organotellurane. These compounds also inhibit human cathepsins B, L, S, and K with second order rate constants higher than those obtained for PV3C. Chloro-telluroxetane inhibits replication of PV in human embryonic rhabdomyosarcoma cells in the low micromolar range and below the toxic level for the host cells. Bis-vinylic organotellurane is more effective as antiviral agent but reduces the cell viability by 20% at 10 mM, a concentration almost completely inhibiting virus growth. This is the first description of inhibition of viral 3C proteinase with antiviral property by this class of compounds.