Biological study and electrochemical characterization of Cu(II) and 1,8-bis-(2-pyridyl)-3,6-dithiaoctane (pdto) complex

Preliminary proliferation assays in human tumor cervix line HeLa, using the coordination compound [Cu(pdto)H2O]2+ (pdto = 1,8-bis-(2-pyridyl)-3,6-dithiaoctane) and its precursors Cu(NO3)2 · 2.5H2O and pdto, were carried out. The results showed that the copper complex has a behavior similar to that of the reference drug cis-platin. No biological activity for the non-coordinated ligand and the copper salt was found. It was established by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy, that the complex [Cu(pdto)H2O]2+ presents an electrochemical reversible Cu(II)/Cu(I) reduction, in acetonitrile solution, meanwhile, the copper salt Cu(NO3)2 · 2.5H2O exhibited an electrochemical irreversible behavior. A comparison between biological and electrochemical results corresponding to [Cu(pdto)H2O]2+ and Cu(NO3)2 · 2.5H2O let us to proposed, the electrochemical reversibility, as one important factor in the antitumoral activity of the copper complex. Due to the nature of the studies presented in this work, other factors like intercalation properties with DNA cannot be neglected in the antitumoral activity of the complex.

Graphical abstractThis work presents a biological study and electrochemical characterization of the compound [Cu(pdto)H2O]2+ (pdto = 1,8-bis-(2-pyridyl)-3,6-dithiaoctane). In a simple way antitumoral activity of this complex is related to its electrochemical reversibility. In contrast, Cu(NO3)2 · 2.5H2O presented electrochemical irreversibility and no biological activity.Figure optionsDownload full-size imageDownload as PowerPoint slide