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Cáceres-Vásquez J, Jara DH, Costamagna J, Martínez-Gómez F, Silva CP, Lemus L, Freire E, Baggio R, Vera C, Guerrero J. Effect of non-covalent self-dimerization on the spectroscopic and electrochemical properties of mixed Cu(i) complexes. RSC Adv 2023; 13:825-838. [PMID: 36686905 PMCID: PMC9810106 DOI: 10.1039/d2ra05341a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 12/06/2022] [Indexed: 01/05/2023] Open
Abstract
A series of six new Cu(i) complexes with ([Cu(N-{4-R}pyridine-2-yl-methanimine)(PPh3)Br]) formulation, where R corresponds to a donor or acceptor p-substituent, have been synthesized and were used to study self-association effects on their structural and electrochemical properties. X-ray diffraction results showed that in all complexes the packing is organized from a dimer generated by supramolecular π stacking and hydrogen bonding. 1H-NMR experiments at several concentrations showed that all complexes undergo a fast-self-association monomer-dimer equilibrium in solution, while changes in resonance frequency towards the high or low field in specific protons of the imine ligand allow establishing that dimers have similar structures to those found in the crystal. The thermodynamic parameters for this self-association process were calculated from dimerization constants determined by VT-1H-NMR experiments for several concentrations at different temperatures. The values for K D (4.0 to 70.0 M-1 range), ΔH (-1.4 to -2.6 kcal mol-1 range), ΔS (-0.2 to 2.1 cal mol-1 K-1 range), and ΔG 298 (-0.8 to -2.0 kcal mol-1 range) are of the same order and indicate that the self-dimerization process is enthalpically driven for all complexes. The electrochemical profile of the complexes shows two redox Cu(ii)/Cu(i) processes whose relative intensities are sensitive to concentration changes, indicating that both species are in chemical equilibrium, with the monomer and the dimer having different electrochemical characteristics. We associate this behaviour with the structural lability of the Cu(i) centre that allows the monomeric molecules to reorder conformationally to achieve a more adequate assembly in the non-covalent dimer. As expected, structural properties in the solid and in solution, as well as their electrochemical properties, are not correlated with the electronic parameters usually used to evaluate R substituent effects. This confirms that the properties of the Cu(i) complexes are usually more influenced by steric effects than by the inductive effects of substituents of the ligands. In fact, the results obtained showed the importance of non-covalent intermolecular interactions in the structuring of the coordination geometry around the Cu centre and in the coordinative stability to avoid dissociative equilibria.
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Affiliation(s)
- Joaquín Cáceres-Vásquez
- Laboratorio de Compuestos de Coordinación y Química Supramolecular, Facultad de Química y Biología, Universidad de Santiago de ChileAv. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33SantiagoChile
| | - Danilo H. Jara
- Facultad de Ingenieria y Ciencias, Universidad Adolfo IbáñezAv. Padre Hurtado 750Viña del MarChile
| | - Juan Costamagna
- Laboratorio de Compuestos de Coordinación y Química Supramolecular, Facultad de Química y Biología, Universidad de Santiago de ChileAv. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33SantiagoChile,Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33SantiagoChile
| | - Fabián Martínez-Gómez
- Laboratorio de Compuestos de Coordinación y Química Supramolecular, Facultad de Química y Biología, Universidad de Santiago de ChileAv. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33SantiagoChile,Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33SantiagoChile
| | - Carlos P. Silva
- Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33SantiagoChile
| | - Luis Lemus
- Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33SantiagoChile
| | - Eleonora Freire
- Gerencia de Investigación y Aplicaciones, Centro Atómico Constituyentes, Comisión Nacional de Energía AtómicaAvenida Gral. Paz 1499, 1650, San MartínBuenos AiresArgentina,Escuela de Ciencia y Tecnología, Universidad Nacional de San Martín, Argentina and Gerencia de Investigación y Aplicaciones, Centro Atómico Constituyentes, Comisión Nacional de Energía AtómicaBuenos AiresArgentina,Member of CONICETArgentina
| | - Ricardo Baggio
- Gerencia de Investigación y Aplicaciones, Centro Atómico Constituyentes, Comisión Nacional de Energía AtómicaAvenida Gral. Paz 1499, 1650, San MartínBuenos AiresArgentina
| | - Cristian Vera
- Laboratorio de Compuestos de Coordinación y Química Supramolecular, Facultad de Química y Biología, Universidad de Santiago de ChileAv. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33SantiagoChile
| | - Juan Guerrero
- Laboratorio de Compuestos de Coordinación y Química Supramolecular, Facultad de Química y Biología, Universidad de Santiago de ChileAv. Libertador Bernardo O'Higgins 3363, Estación Central, Casilla 40, Correo 33SantiagoChile
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Romo AIB, Carepo MP, Levín P, Nascimento OR, Díaz DE, Rodríguez-López J, León IE, Bezerra LF, Lemus L, Diógenes ICN. Synergy of DNA intercalation and catalytic activity of a copper complex towards improved polymerase inhibition and cancer cell cytotoxicity. Dalton Trans 2021; 50:11931-11940. [PMID: 34374389 DOI: 10.1039/d1dt01358k] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Improving the binding of metal complexes to DNA to boost cancer cell cytotoxicity requires fine tuning of their structural and chemical properties. Copper has been used as a metal center in compounds containing intercalating ligands due to its ability to catalytically generate reactive oxygen species (ROS), such as hydroxyl radicals (OH˙). We envision the synergy of DNA binding and ROS generation in proximity to target DNA as a powerful chemotherapy treatment. Here, we explore the use of [Cu(2CP-Bz-SMe)]2+ (2CP-Bz-SMe = 1,3-bis(1,10-phenanthrolin-2-yloxy)-N-(4-(methylthio)benzylidene)propan-2-amine) for this purpose by characterizing its cytotoxicity, DNA binding, and ability to affect DNA replication through the polymerase chain reaction - PCR and nuclease assays. We determined the binding (Kb) and Stern-Volmer constants (KSV) for complex-DNA association of 5.8 ± 0.14 × 104 and 1.64 (±0.08), respectively, through absorption titration and competitive fluorescence experiments. These values were superior to those of other Cu-complex intercalators. We hypothesize that the distorted trigonal bipyramidal geometry of [Cu(2CP-Bz-SMe)]2+ allows the phenanthroline fragments to be better accommodated into the DNA double helix. Moreover, the aromaticity of these fragments increases the local hydrophobicity thus increasing the affinity for the hydrophobic domains of DNA. Nuclease assays in the presence of common reducing agents ascorbic acid, nicotinamide adenine dinucleotide, and glutathione showed the effective degradation of DNA due to the in situ generation of OH˙. The [Cu(2CP-Bz-SMe)]2+ complex showed cytotoxicity against the following human cancer cells lines A549, MCF-7, MDA-MB-231 and MG-63 with half maximal inhibitory concentration (IC50) values of 4.62 ± 0.48, 5.20 ± 0.76, 5.70 ± 0.42 and 2.88 ± 0.66 μM, respectively. These low values of IC50, which are promising if compared to that of cisplatin, are ascribed to the synergistic effect of ROS generation with the intercalation ability into the DNA minor grooves and blocking DNA replication. This study introduces new principles for synergizing the chemical and structural properties of intercalation compounds for improved drug-DNA interactions targeting cancer.
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Affiliation(s)
- Adolfo I B Romo
- Departamento de Química Orgânica e Inorgânica, Centro de Ciências, Universidade Federal do Ceará, Cx. Postal 6021, Fortaleza, CE 60451-970, Brasil.
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Martínez NP, Isaacs M, Oliver AG, Ferraudi G, Lappin AG, Guerrero J. Effects of non-covalent interactions on the electronic and electrochemical properties of Cu(i) biquinoline complexes. Dalton Trans 2018; 47:13171-13179. [PMID: 30177987 DOI: 10.1039/c8dt02722f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A Cu(i) complex {[CuI(biq)2]ClO4-biq} with biq = 2,2'-biquinoline was prepared, fully characterized and its properties compared with those of the well-known [CuI(biq)2]ClO4 complex. The crystal structures were obtained for both complexes (crystal structure for [CuI(biq)2]ClO4 has not been previously reported). Complex [CuI(biq)2]ClO4 crystallizes as a racemate where each enantiomer has a different τ4 value while compound {[CuI(biq)2]ClO4-biq} crystallizes as a non-chiral supramolecular aggregate with an uncoordinated biq molecule forming a π-π stacking interaction with a coordinated biq. 1H-NMR spectroscopy in non-coordinating solvents reveals that structures in solution are similar to those in the solid phase, confirming the presence of a supramolecular arrangement for compound {[CuI(biq)2]ClO4-biq}. The stability of the non-covalent aggregate in solution of {[CuI(biq)2]ClO4-biq} causes significant differences between the spectroscopic and electrochemical properties of {[CuI(biq)2]ClO4-biq} and [CuI(biq)2]ClO4.
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Affiliation(s)
- Natalia P Martínez
- Facultad de Química, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile
| | - Mauricio Isaacs
- Facultad de Química, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, 7820436 Macul, Santiago, Chile and Centro de Investigación en Nanotecnología y Materiales Avanzados CIEN-UC, Pontificia Universidad Católica de Chile, Chile and UC-Energy Research Center, Pontificia Universidad Católica de Chile, Chile
| | - Allen G Oliver
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, IN 46556-5670, USA.
| | - G Ferraudi
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, IN 46556-5670, USA. and Radiation Laboratory, University of Notre Dame, Notre Dame, IN 46556-5670, USA
| | - A Graham Lappin
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, IN 46556-5670, USA.
| | - Juan Guerrero
- Facultad de Química y Biología, Universidad de Santiago de Chile, Libertador Bernardo O'Higgins 3363, Estación central, Santiago, Chile.
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Park S, Lee J, Jeong JH, Lee H, Nayab S. Palladium(II) complexes containing N,N′-bidentate imine ligands derived from picolinaldehyde and substituted anilines: Synthesis, structure and polymerisation of methyl methacrylate. Polyhedron 2018. [DOI: 10.1016/j.poly.2018.05.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Morales EH, Pinto CA, Luraschi R, Muñoz-Villagrán CM, Cornejo FA, Simpkins SW, Nelson J, Arenas FA, Piotrowski JS, Myers CL, Mori H, Vásquez CC. Accumulation of heme biosynthetic intermediates contributes to the antibacterial action of the metalloid tellurite. Nat Commun 2017; 8:15320. [PMID: 28492282 PMCID: PMC5437285 DOI: 10.1038/ncomms15320] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 03/21/2017] [Indexed: 01/08/2023] Open
Abstract
The metalloid tellurite is highly toxic to microorganisms. Several mechanisms of action have been proposed, including thiol depletion and generation of hydrogen peroxide and superoxide, but none of them can fully explain its toxicity. Here we use a combination of directed evolution and chemical and biochemical approaches to demonstrate that tellurite inhibits heme biosynthesis, leading to the accumulation of intermediates of this pathway and hydroxyl radical. Unexpectedly, the development of tellurite resistance is accompanied by increased susceptibility to hydrogen peroxide. Furthermore, we show that the heme precursor 5-aminolevulinic acid, which is used as an antimicrobial agent in photodynamic therapy, potentiates tellurite toxicity. Our results define a mechanism of tellurite toxicity and warrant further research on the potential use of the combination of tellurite and 5-aminolevulinic acid in antimicrobial therapy. The mechanisms of action of the antibacterial metalloid tellurite are unclear. Here, the authors show that tellurite induces an accumulation of hydroxyl radical and intermediates of heme biosynthesis in E. coli, and that the heme precursor 5-aminolevulinic acid potentiates tellurite toxicity.
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Affiliation(s)
- Eduardo H Morales
- Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 9170022, Chile
| | - Camilo A Pinto
- Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 9170022, Chile
| | - Roberto Luraschi
- Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 9170022, Chile
| | | | - Fabián A Cornejo
- Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 9170022, Chile
| | - Scott W Simpkins
- University of Minnesota-Twin Cities, Bioinformatics and Computational Biology, Minneapolis, Minnesota 55455, USA
| | - Justin Nelson
- University of Minnesota-Twin Cities, Bioinformatics and Computational Biology, Minneapolis, Minnesota 55455, USA
| | - Felipe A Arenas
- Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 9170022, Chile
| | | | - Chad L Myers
- University of Minnesota-Twin Cities, Bioinformatics and Computational Biology, Minneapolis, Minnesota 55455, USA.,University of Minnesota-Twin Cities, Department of Computer Science and Engineering, Minneapolis, Minnesota 55455, USA
| | - Hirotada Mori
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0101, Japan
| | - Claudio C Vásquez
- Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago 9170022, Chile
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