SPECTROSCOPIC, ELECTROCHEMICAL AND CYTOTOXIC EVALUATION OF COPPER (II) COMPLEXES WITH TRIDENTATE LIGANDS
copper complexes; UV-Vis; IV; NMR; fluorescence; electrochemistry
Copper complexes have shown relevant cytotoxic activity, participating in the reactions responsible for DNA breakage and consequent cell death. Thus, the present work aims at the synthesis and characterization of 4-({bis[pyridin-2-yl)methyl]amino}methyl)-7-hydroxy-2H-1-benzopyran-2-one (L1) and N,N-Bis(2-hydroxy-naphthylmethyl)methylamine (L2) and [Cu(phen)(L1)](PF6)2 and [Cu(phen)(L2)] complexes, referred to as C1phen and C2phen, respectively, obtained from the precursor [Cu(phen)Cl2]. The results of IR and NMR indicated the formation of L1 and L2. For the C2phen complex, the IV showed the coordination of L2 to the metal due to the absence of νO-H, whereas for the C1phen it was possible to confirm its formation through the characteristic vibrational modes. The UV-vis showed a shift of the d-d transition to the more energetic region compared to the precursor complex. The emission spectrum confirmed that the [Cu(phen)(L1)](PF6)2 and [Cu(phen)(L2)] complexes exhibited fluorescence, even after coordination, whereas the electrochemistry showed for the compound C2phen two quasi-reversible redox processes Cu2+/1+ and Cu1+/0. For the C1phen it was possible to visualize only the process related to the Cu2+/1+ redox pair in the applied potential range. The cytotoxic potential of the complexes of interest was evaluated with two human tumor cell lines (A2058 and SiHa) by the MTT assay using the IC50 as the parameter. Like the complexes, the ligands also induced a concentration-dependent cytotoxic effect, however, the complexes demonstrated the highest cytotoxic response. Cell death and cell cycle were also assessed by flow cytometry, where C1phen and C2phen complexes mainly induced late apoptosis. Through the cell cycle, it was possible to conclude that for the SiHa, the C1phen complex inhibited the progression of the cycle in the S phase, whereas for the A2058, both C1phen and also for C2phen, the interruption occurred in the G2-M phase. Therefore, with the biological results, it is possible to suggest a possible application in the treatment of cancer.