DESIGN OF NOVEL ORGANIC MOLECULES AND METAL COMPLEXES WITH BIOLOGICAL PROPERTIES

This thesis summarizes the research activity I carried out during the three years of my PhD, focusing on the design and study of bioactive molecules and Copper (II) complexes, as well as the development of innovative analytical methods applied to different systems. The core of this work is focused on synthesis and characterization of a series of copper (II) complexes bearing different classes of organic ligands, with the aim of discovering novel potential anticancer molecules. The biological studies were performed both in collaboration with Prof. Petr Vaňhara in Masaryk University, Brno (CZ) and during my PhD exchange period in his laboratories. The metal complexes were tested in vitro on different cell lines and exhibited cytotoxicity at the micromolar level. Their mechanism of action was investigated through the study of the unfolded protein response (UPR) pathways, and in most cases, the results confirmed the activation of the pro-apoptotic branch of UPR suggesting the involvement of Endoplasmic reticulum (ER) stress in their anticancer mechanism. The relevance of the ER stress in anticancer activity prompted us to deeply investigate the molecular mechanism exploited by the copper (II) complexes to induce UPR. For this purpose, three novel copper complexes were designed as prototypes for the study of ER stress both in lung adenocarcinoma cells (A549) and in the healthy expandable lung epithelial progenitors’ cells (ELEP), recently differentiated by Prof. Vaňhara’s group. The obtained results confirmed that the studied complexes were able to inhibit cancer cell proliferation and trigger ER stress, in a very pronounced way on ELEP cells. This specific result highlights the importance of the investigation in healthy systems, to clarify the biochemical action mechanism of ligand/complexes, and to design safer and more selective therapeutic strategies. A panel of ligands based on thiosemicarbazone was also synthetized and their inhibitor activity towards tyrosinase enzyme was investigated in collaboration with Prof. A. Fais at University of Cagliari. These molecules showed promising tyrosinase inhibitory activity, supported by both experimental and theoretical studies. These new molecules shown a sun protection factor (SPF) higher than the natural reference compounds, highlighting their potential as candidates for cosmetic applications. During these three years I also carried out a parallel project focused on developing novel analytical methods for applications in biological field. One of these, consisted in a combined Intact Cell MALDI-TOF spectrometry with different machine learning algorithms, with the aim to recognise minute change induced by single gene silencing. This approach resulted to be a powerful strategy to detect subtle alteration, resulting from the silencing of a single gene, distinguishing not only control from treated cells but also the proportions between them, in a fast, cost-effectiveness and accurate procedure (accuracy 90%).