Metalociclos autoensamblados de Pt(II) como potenciales metalofármacos antitumorales

Abstract

The present dissertation is divided in three sections. On the first part, we have designed and developed a new synthetic methodology that has enabled the preparation of ligands previously published by the research group in a more efficient manner. The assembly of these ligands with metallic centers of Pd(II) and Pt(II) at low concentrations leads to the formation of mononuclear metallacycles M1L1. In addition, through this strategy new analogue ligands with different size and functionalization were obtained. The process of Pd(II)/Pt(II)-directed self-assembly of the new metallacycles has been explored, observing that apart from the expected mononuclear metallacycles, dinuclear species M2L2 appear at high concentrations. We have found that the speciation can be controlled by the application of external stimuli (concentration and/or addition of a substrate). The second part of this work is focused on the study of the interaction of Pt(II) metallacycles with duplex and G-quadruplex DNA structures. We began by studying the interaction of three differently-sized quadrangular metallacycles of type M2L2, previously published by this research group. The purpose of this work was to determine the possible influence of size of the metallacycles on the interaction with DNA. The results showed that the smallest Pt-box display less activity but greater selectivity for a quadruplex formed in c-Kit gene. The results obtained by means of spectroscopic techniques were reinforced by carrying out cell tests. Finally, we have studied the interaction of a more diverse family of M1L1 and M2L2 metallacycles with double-helix and G-quadruplex DNA. The metallacycle showing a better interaction profile and selectivity, were subjected to further spectroscopic studies. Of all the metallacycles analyzed, the one with the best absorption/emission profile was subjected to further biological studies. Those revealed that the analyzed metallacycle was able to enter cancer cells, to reach the nucleus and subsequently bind G-quadruplex structures present in the nucleolus, being the first example of a fluorescent Pt(II) metallacycle capable of exhibiting this behaviour.