Browsing by Author "Oliveira, Tamires Donizeth de"

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    Antitumor activity of Pd(II) complexes with N,S or O,S coordination modes of acylthiourea ligands.
    (2020) Stevens, Ana María Plutín; Ramos Cairo, Raúl; Mocelo, Raúl; Alvarez Hernández, Anislay; Castellano, Eduardo Ernesto; Cominetti, Márcia Regina; Oliveira, Katia Mara de; Oliveira, Tamires Donizeth de; Silva, Thales E. M.; Oliveira, Rodrigo Corrêa de; Batista, Alzir Azevedo
    Seven new complexes (1–7) of Pd(II) with N-alkyl- and N,N-dialkyl-N0 -acylthioureas were prepared and characterized by elemental analysis and spectroscopic techniques. The crystal structures of the coordination compounds [PdCl(PPh3)(5-cloropiridyl-N0 -benzoylthioureato-k2 N,S)] (2), cis-[Pd(PPh3)2 (N-morpholyn-N0 -benzoylthioureato-k2 O,S)]PF6 (4) and cis-[Pd(PPh3)2(N,N-diphenyl-N0 -thiophenylth ioureato-k2 O,S)]PF6 (7) were determined by X-ray crystallography. The present study reports on an inter esting contribution on the chemistry of Pd(II)/acylthiourea complexes, where the use of monosubstituted acylthiourea conducts to formation of neutral complexes with general formula [Pd(Cl)(PPh3) (acylthiourea)], with a N,S-coordination mode. On the other hand, cationic complexes with formula [Pd (PPh3)2(acylthiourea)]+ , with O,S bidentately coordinated to the metal, are obtained by using a disubsti tuted acylthiourea derivative. The antitumor activity of the N-alkyl- and N,N-dialkyl-N0 -acylthiourea ligands and their palladium (II) complexes with synthesized triphenylphosphine were evaluated against the growth of the DU-145 tumor cells (prostate cancer cells), (MDA-MB-231 (breast cancer cells), L929 (healthy mouse cells). The ligands are not cytotoxic, but the complexes showed good cytotoxicity against the tumor cells tested in this work, and were even better, when compared to the IC50 reported for the cis platin. The complexes showed better activity results in MDA-MB-231 tumor cells, than for the DU-145 tumor cells. Complexes 1 and 6 showed high cytotoxic activity at low micromolar concentrations (IC50 = 1.93 ± 0.45, 0.62 ± 0.08 lM) against MDA-MB-231 (human breast cancer cells). This result indicated that the binding of the ligands to the metal center increases their antitumor activity.
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    Understanding the conformational changes and molecular structure of furoyl thioureas upon substitution.
    (2017) Ramos Cairo, Raúl; Stevens, Ana María Plutín; Oliveira, Tamires Donizeth de; Batista, Alzir Azevedo; Castellano, Eduardo Ernesto; Duque, Julio; Soria, Delia B.; Fantoni, Adolfo C.; Correa, Rodrigo de Souza; Erbene, Mauricio F.
    1-Acyl thioureas [R1C(O)NHC(S)NR2R3] are shown to display conformational flexibility depending on the degree of substitution at the nitrogen atom. The conformational landscape and structural features for two closely related thioureas having R1=2-furoyl have been studied. The un-substituted 2-furoyl thiourea (I) and its dimethyl analogue, i.e. 1-(2-furoyl)-3,3-dimethyl thiourea (II), have been synthesized and fully characterized by spectroscopic (FT-IR, 1H and 13C NMR) and elemental analysis. According to single crystal X-ray diffraction analysis, compounds I and II crystallize in the monoclinic space group P21/c. In the compound I, the trans–cis geometry of the almost planar thiourea unit is stabilized by intramolecular N\\H⋯O_C hydrogen bond between the H atom of the cis thioamide and the carbonyl O atom. In compound II, however, the acyl thiourea group is non-planar, in good agreement with the potential energy curve computed at the B3LYP/6-31+G(d,p) level of approximation. Centrosymmetric dimers generated by intermolecular N\\H⋯S_C hydrogen bond forming R2 2 (8) motif are present in the crystals. Intermolecular interactions have been rationalized in terms of topological partitions of the electron distributions and Hirshfeld surface analysis, which showed the occurrence of S⋯H, O⋯H and H⋯H contacts that display an important role to crystal packing stabilization of both thiourea derivatives.