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447 results on '"Castellano, Eduardo E."'

14. Copper(I)/Triphenylphosphine Complexes Containing Naphthoquinone Ligands as Potential Anticancer Agents.

Author

Leite, Celisnolia M., Araujo-Neto, João H., Guedes, Adriana P. M., Costa, Analu R., Demidoff, Felipe C., Netto, Chaquip D., Castellano, Eduardo E., Nascimento, Otaciro R., and Batista, Alzir A.

Subjects
ANTINEOPLASTIC agents, NAPHTHOQUINONE, ELECTRON paramagnetic resonance, CELL morphology, REACTIVE oxygen species
Abstract

Four new Cu/PPh3/naphtoquinone complexes were synthesized, characterized (IR, UV/visible, 1D/2D NMR, mass spectrometry, elemental analysis, and X-ray diffraction), and evaluated as anticancer agents. We also investigated the reactive oxygen species (ROS) generation capacity of complex 4, considering the well-established photochemical property of naphthoquinones. Therefore, employing the electron paramagnetic resonance (EPR) "spin trap", 5,5-dimethyl-1-pyrroline N-oxide (DMPO) technique, we identified the formation of the characteristic •OOH species (hydroperoxyl radical) adduct even before irradiating the solution containing complex 4. As the irradiation progressed, this radical species gradually diminished, primarily giving rise to a novel species known as •DMPO-OH (DMPO + •OH radical). These findings strongly suggest that Cu(I)/PPh3/naphthoquinone complexes can generate ROS, even in the absence of irradiation, potentially intensifying their cytotoxic effect on tumor cells. Interpretation of the in vitro cytotoxicity data of the Cu(I) complexes considered their stability in cell culture medium. All of the complexes were cytotoxic to the lung (A549) and breast tumor cell lines (MDA-MB-231 and MCF-7). However, the higher toxicity for the lung (MRC5) and breast (MCF-10A) non-tumoral cells resulted in a low selectivity index. The morphological analysis of MDA-MB-231 cells treated with the complexes showed that they could cause decreased cell density, loss of cell morphology, and loss of cell adhesion, mainly with concentrations higher than the inhibitory concentration of 50% of cell viability (IC50) values. Similarly, the clonogenic survivance of these cells was affected only with concentrations higher than the IC50 values. An antimigratory effect was observed for complexes 1 and 4, showing around 20–40% of inhibition of wound closure in the wound healing experiments. [ABSTRACT FROM AUTHOR]

Published
2023
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15. Biomimetic catalysis of nitrite reductase enzyme using copper complexes in chemical and electrochemical reduction of nitrite.

Author

Ferreira, Millena P., Castro, Caio B., Honorato, João, He, Sheng, Gonçalves Guimarães Júnior, Walber, Esmieu, Charlene, Castellano, Eduardo E., de Moura, André F., Truzzi, Daniela R., Nascimento, Otaciro R., Simonneau, Antoine, and Marques Netto, Caterina G. C.

Subjects
NITRITE reductase, COPPER enzymes, CHEMICAL reduction, ELECTRON paramagnetic resonance spectroscopy, COPPER compounds, ELECTROLYTIC reduction, ELECTRON paramagnetic resonance
Abstract

Copper nitrite reductase mimetics were synthesized using three new tridentate ligands sharing the same N,N,N motif of coordination. The ligands were based on L -proline modifications, attaching a pyridine and a triazole to the pyrrolidine ring, and differ by a pendant group (R = phenyl, n-butyl and n-propan-1-ol). All complexes coordinate nitrite, as evidenced by cyclic voltammetry, UV-Vis, FTIR and electron paramagnetic resonance (EPR) spectroscopies. The coordination mode of nitrite was assigned by FTIR and EPR as κ2O chelate mode. Upon acidification, EPR experiments indicated a shift from chelate to monodentate κO mode, and 15N NMR experiments of a Zn2+ analogue, suggested that the related Cu(II) nitrous acid complex may be reasonably stable in solution, but in equilibrium with free HONO under non catalytic conditions. Reduction of nitrite to NO was performed both chemically and electrocatalytically, observing the highest catalytic activities for the complex with n-propan-1-ol as pendant group. These results support the hypothesis that a hydrogen bond moiety in the secondary coordination sphere may aid the protonation step. [ABSTRACT FROM AUTHOR]

Published
2023
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31. On the synthesis and structures of the complexes [RuCl(L)(dppb)(N–N)]PF 6 (L = CO, py or 4-NH 2py; dppb = 1,4-bis(diphenylphosphino)butane; N–N = 2,2′-bipyridine or 1,10-phenanthroline) and [(dppb)(CO)Cl 2-Ru-pz-RuCl 2(CO)(dppb)] (pz = pyrazine)

Author

Frazão Barbosa, Marilia I., Valle, Eliana M.A., Queiroz, Salete L., Ellena, Javier, Castellano, Eduardo E., Malta, Valéria R.S., de Sousa, Jackson R., Piro, Oscar, de Araujo, Márcio P., and Batista, Alzir A.

Published
2010
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39. Mass spectrometry of 1,2,5-oxadiazole N-oxide derivatives: use of deuterated analogues in fragmentation pattern studies

Author

Cerecetto Hugo, González Mercedes, Seoane Gustavo, Stanko Carola, Piro Oscar E., and Castellano Eduardo E.

Subjects
1,2,5-oxadiazole N-oxide, D-labeled furoxan, mass fragmentation, EI/MS, Chemistry, QD1-999
Abstract

This paper reported on the study of fragmentation pattern in mass spectrometry of 1,2,5-oxadiazole N-oxide derivatives involving deuterium-labeled analogues to identify some critical fragmentations. A neutral CH2O loss from 3-hydroxymethyl-N2-oxide-4-phenyl-1,2,5-oxadiazole was confirmed with the corresponding mono-deuterated analogue. An OH loss, involving the oxygen of N-oxide, via beta-H and delta-H rearrangement, was clearly revealed from 3-(4-methylpiperazine-1-ylmethyl)-N2 -oxide-4-phenyl-1,2,5-oxadiazole using the adequate tetra-deuterated analogue. N-oxide isomer and deoxygenated analogues were also used to confirm the participation of the oxide moiety in the fragmentation process.

Published
2004

40. Novel Organophosphorus Cage Compound Produced by an Unexpected Oxidative Coupling of 1,2,4-Triphosphole: Crystal and Molecular Structures of Two Isomers of Formula P6C4But4 CHSiMe3

Author

Araujo Maria Helena, Rajão Daniel A., Doriguetto Antonio C., Ellena Javier, Castellano Eduardo E., Hitchcock Peter B., and Caliman Vinicius

Subjects
organophosphorus compounds, multinuclear NMR, X-ray molecular structure, Chemistry, QD1-999
Abstract

Reaction of Li(P3C2Bu t2 ) with BrCH(SiMe3)2 results in a novel organophosphorus compound with the formula, P6C4Bu t4 CHSiMe3 (1). Compound 1 was fully characterised spectroscopically and its unique molecular structure determined by single crystal X-ray diffraction. Another isomer (2) with a saturated structure was also fully characterised.

Published
2002

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