title: A series of mononuclear Co(III) complexes using tridentate N,O-donor ligands: chemical properties and cytotoxicity activity.
abstract: Continuing our interest in tridentate ligands to develop new prototypes of cobalt-based metallodrugs for combating cancer, modifications in the backbone of HL1, [(2-hydroxybenzyl)(2-(pyridil-2-yl)ethyl]amine) were proposed in order to modulate the redox potential of new Co(III) complexes. Three ligands with electron withdrawing groups were synthesized: HL2: [(2-hydroxy-5-nitrobenzyl)(2-(pyridil-2-yl)ethyl]amine); HL3: [(2-hydroxybenzyl)(2-(pyridil-2-yl)ethyl]imine) and HL4: [(2-hydroxy-5-nitrobenzyl)(2-(pyridil-2-yl)ethyl]imine). They were used to obtain the respective mononuclear complexes 2, 3 and 4, which are discussed compared to the previous reported complex 1 (obtained from HL1). The new complexes were characterized and studied by several techniques including X-ray crystallography, elemental and conductimetric analysis, IR, UV-vis and (1)H NMR spectroscopies, and electrochemistry. The substitutions of the group in the para position of the phenol (HL1 and HL2) and the imine instead of the amine (HL3 and HL4), promote anodic shifts in the complexes reduction potentials. The influence of these substitutions in the biological activities of the Co(III) complexes against the murine melanoma cell line (B16F10) was also evaluated. Little effect was observed on cellular viability decrease for all free ligands, however the coordination to Co(III) enhances their activities in the following range: 1>4≈2>3. The data suggest that no straight correlation can be addressed between the reduction potential of the Co(III) center and the cell viability.
authors: Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors: Elizabeth Teixeira
authors: ET
authors: Souza
authors: Paulo José Sousa
authors: PJ
authors: Maia
authors: Erica Melo
authors: EM
authors: Azevedo
authors: Carlos Roland
authors: CR
authors: Kaiser
authors: Jackson Antônio Lamounier Camargos
authors: JA
authors: Resende
authors: Carlos Basílio
authors: CB
authors: Pinheiro
authors: Tassiele Andrea
authors: TA
authors: Heinrich
authors: Roberto Santana
authors: RS
authors: da Silva
authors: Marciela
authors: M
authors: Scarpellini
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003035:Cobalt; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D018360:Crystallography, X-Ray; D004354:Drug Screening Assays, Antitumor; D004563:Electrochemistry; D020128:Inhibitory Concentration 50; D051379:Mice; D008958:Models, Molecular; D008968:Molecular Conformation; D010084:Oxidation-Reduction
chemical_list: D000970:Antineoplastic Agents; D056831:Coordination Complexes; D003035:Cobalt