Novel 8-Hydroxyquinoline-Derived V(IV)O, Ni(II), and Fe(III) Complexes: Synthesis, Characterization, and In Vitro Cytotoxicity Against Tumor Cells

We report the synthesis and characterization of five novel metal complexes. Three of them are vanadium complexes with the general formula <b>[VO(L<sup>n</sup>)<sub>2</sub>]</b>, where L<sup>n</sup> are Schiff bases derived from the condensation of 2-ca...

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Main Authors: Joana Lopes, Leonor Côrte-Real, Íris Neto, Alice Alborghetti, Maël Dejoux, Nora V. May, Xavier Fontrodona, Isabel Romero, Alexandra M. M. Antunes, Catarina Pinto Reis, Maria Manuela Gaspar, Isabel Correia
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Language:English
Published: MDPI AG 2025-05-01
Series:Inorganics
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Online Access:https://www.mdpi.com/2304-6740/13/5/150
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author Joana Lopes
Leonor Côrte-Real
Íris Neto
Alice Alborghetti
Maël Dejoux
Nora V. May
Xavier Fontrodona
Isabel Romero
Alexandra M. M. Antunes
Catarina Pinto Reis
Maria Manuela Gaspar
Isabel Correia
author_facet Joana Lopes
Leonor Côrte-Real
Íris Neto
Alice Alborghetti
Maël Dejoux
Nora V. May
Xavier Fontrodona
Isabel Romero
Alexandra M. M. Antunes
Catarina Pinto Reis
Maria Manuela Gaspar
Isabel Correia
author_sort Joana Lopes
collection DOAJ
description We report the synthesis and characterization of five novel metal complexes. Three of them are vanadium complexes with the general formula <b>[VO(L<sup>n</sup>)<sub>2</sub>]</b>, where L<sup>n</sup> are Schiff bases derived from the condensation of 2-carbaldehyde-8-hydroxyquinoline with either 4-(2-aminoethyl)morpholine (L<sup>1</sup>), 3-morpholinopropylamine (L<sup>2</sup>) or 1-(2-aminoethyl)piperidine (L<sup>3</sup>). The two other metal complexes are <b>[Ni(L<sup>1</sup>)<sub>2</sub>]</b> and <b>[Fe(L<sup>1</sup>)<sub>2</sub>]Cl</b>. They were characterized by analytical, spectroscopic (Fourier transform infrared, UV-visible absorption), and mass spectrometric techniques as well as by single-crystal X-ray diffraction (for all <b>[VO(L<sup>n</sup>)<sub>2</sub>]</b> complexes and <b>[Ni(L<sup>1</sup>)<sub>2</sub>]</b>). While, in the crystal structure, the V(IV)O complexes show distorted square–pyramidal geometry with the ligands bound as bidentate through quinolate NO donors, the Ni(II) complex shows octahedral geometry with two ligand molecules coordinated through NNO donors. Stability studies in aqueous media revealed that the vanadium complexes are not stable, undergoing oxidation to VO<sub>2</sub>(L), which was corroborated by <sup>51</sup>V NMR and MS. This behavior is also observed in organic media, though at a significantly slower rate. The Ni complex exhibited small spectral changes over time in aqueous media. Nonetheless, all compounds show enhanced stability in the presence of bovine serum albumin (BSA). Fluorescence studies carried out for the Ni(II) and Fe(III) complexes indicate reversible binding to albumin. The cytotoxicity of the L<sup>1</sup> metal complexes was assessed on melanoma (B16F10 and A375) and colon cancer (CT-26 and HCT-116) cell lines, with 5-fluorouracil (5-FU) as a reference drug. The V- and Ni complexes showed the lowest IC<sub>50</sub> values (<10 μM) in either A375 or HCT-116 cells after 48 h of incubation, while the Fe(III) complex presented minimal antiproliferative effects. The complexes were generally more cytotoxic to human than murine cancer cells. Synergistic in vitro studies with 5-FU revealed antagonism in most cases, except in A375 cells, where an additive effect was observed for the combination with the V-complex. Overall, these compounds show promising potential for cancer treatment, mostly for melanoma.
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spelling doaj-art-e4ad68d9df904ba38a0852dd9bfd0f0c2025-08-20T02:33:46ZengMDPI AGInorganics2304-67402025-05-0113515010.3390/inorganics13050150Novel 8-Hydroxyquinoline-Derived V(IV)O, Ni(II), and Fe(III) Complexes: Synthesis, Characterization, and In Vitro Cytotoxicity Against Tumor CellsJoana Lopes0Leonor Côrte-Real1Íris Neto2Alice Alborghetti3Maël Dejoux4Nora V. May5Xavier Fontrodona6Isabel Romero7Alexandra M. M. Antunes8Catarina Pinto Reis9Maria Manuela Gaspar10Isabel Correia11Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Professor Gama Pinto, 1649-003 Lisboa, PortugalCentro de Química Estrutural, Institute of Molecular Sciences and Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, PortugalResearch Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Professor Gama Pinto, 1649-003 Lisboa, PortugalCentro de Química Estrutural, Institute of Molecular Sciences and Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, PortugalCentro de Química Estrutural, Institute of Molecular Sciences and Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, PortugalCentre for Structural Sciences, HUN-REN Research Centre for Natural Sciences, Magyar Tudósok Körútja 2, 1117 Budapest, HungaryDepartament de Química and Serveis Técnicas de Recerca, Universitat de Girona, C/M. Aurèlia Campmany, 69, E-17003 Girona, SpainDepartament de Química and Serveis Técnicas de Recerca, Universitat de Girona, C/M. Aurèlia Campmany, 69, E-17003 Girona, SpainCentro de Química Estrutural, Institute of Molecular Sciences and Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, PortugalResearch Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Professor Gama Pinto, 1649-003 Lisboa, PortugalResearch Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Professor Gama Pinto, 1649-003 Lisboa, PortugalCentro de Química Estrutural, Institute of Molecular Sciences and Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, PortugalWe report the synthesis and characterization of five novel metal complexes. Three of them are vanadium complexes with the general formula <b>[VO(L<sup>n</sup>)<sub>2</sub>]</b>, where L<sup>n</sup> are Schiff bases derived from the condensation of 2-carbaldehyde-8-hydroxyquinoline with either 4-(2-aminoethyl)morpholine (L<sup>1</sup>), 3-morpholinopropylamine (L<sup>2</sup>) or 1-(2-aminoethyl)piperidine (L<sup>3</sup>). The two other metal complexes are <b>[Ni(L<sup>1</sup>)<sub>2</sub>]</b> and <b>[Fe(L<sup>1</sup>)<sub>2</sub>]Cl</b>. They were characterized by analytical, spectroscopic (Fourier transform infrared, UV-visible absorption), and mass spectrometric techniques as well as by single-crystal X-ray diffraction (for all <b>[VO(L<sup>n</sup>)<sub>2</sub>]</b> complexes and <b>[Ni(L<sup>1</sup>)<sub>2</sub>]</b>). While, in the crystal structure, the V(IV)O complexes show distorted square–pyramidal geometry with the ligands bound as bidentate through quinolate NO donors, the Ni(II) complex shows octahedral geometry with two ligand molecules coordinated through NNO donors. Stability studies in aqueous media revealed that the vanadium complexes are not stable, undergoing oxidation to VO<sub>2</sub>(L), which was corroborated by <sup>51</sup>V NMR and MS. This behavior is also observed in organic media, though at a significantly slower rate. The Ni complex exhibited small spectral changes over time in aqueous media. Nonetheless, all compounds show enhanced stability in the presence of bovine serum albumin (BSA). Fluorescence studies carried out for the Ni(II) and Fe(III) complexes indicate reversible binding to albumin. The cytotoxicity of the L<sup>1</sup> metal complexes was assessed on melanoma (B16F10 and A375) and colon cancer (CT-26 and HCT-116) cell lines, with 5-fluorouracil (5-FU) as a reference drug. The V- and Ni complexes showed the lowest IC<sub>50</sub> values (<10 μM) in either A375 or HCT-116 cells after 48 h of incubation, while the Fe(III) complex presented minimal antiproliferative effects. The complexes were generally more cytotoxic to human than murine cancer cells. Synergistic in vitro studies with 5-FU revealed antagonism in most cases, except in A375 cells, where an additive effect was observed for the combination with the V-complex. Overall, these compounds show promising potential for cancer treatment, mostly for melanoma.https://www.mdpi.com/2304-6740/13/5/150metal-based complexes8-hydroxyquinolinemorpholineSchiff basesanticancer
spellingShingle Joana Lopes
Leonor Côrte-Real
Íris Neto
Alice Alborghetti
Maël Dejoux
Nora V. May
Xavier Fontrodona
Isabel Romero
Alexandra M. M. Antunes
Catarina Pinto Reis
Maria Manuela Gaspar
Isabel Correia
Novel 8-Hydroxyquinoline-Derived V(IV)O, Ni(II), and Fe(III) Complexes: Synthesis, Characterization, and In Vitro Cytotoxicity Against Tumor Cells
Inorganics
metal-based complexes
8-hydroxyquinoline
morpholine
Schiff bases
anticancer
title Novel 8-Hydroxyquinoline-Derived V(IV)O, Ni(II), and Fe(III) Complexes: Synthesis, Characterization, and In Vitro Cytotoxicity Against Tumor Cells
title_full Novel 8-Hydroxyquinoline-Derived V(IV)O, Ni(II), and Fe(III) Complexes: Synthesis, Characterization, and In Vitro Cytotoxicity Against Tumor Cells
title_fullStr Novel 8-Hydroxyquinoline-Derived V(IV)O, Ni(II), and Fe(III) Complexes: Synthesis, Characterization, and In Vitro Cytotoxicity Against Tumor Cells
title_full_unstemmed Novel 8-Hydroxyquinoline-Derived V(IV)O, Ni(II), and Fe(III) Complexes: Synthesis, Characterization, and In Vitro Cytotoxicity Against Tumor Cells
title_short Novel 8-Hydroxyquinoline-Derived V(IV)O, Ni(II), and Fe(III) Complexes: Synthesis, Characterization, and In Vitro Cytotoxicity Against Tumor Cells
title_sort novel 8 hydroxyquinoline derived v iv o ni ii and fe iii complexes synthesis characterization and in vitro cytotoxicity against tumor cells
topic metal-based complexes
8-hydroxyquinoline
morpholine
Schiff bases
anticancer
url https://www.mdpi.com/2304-6740/13/5/150
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