Metal complexes with biological activity

Cancer is a group a diseases that involves abnormal cell growth with potential to invade or spread to other parts of the body, and it represents the second leading cause of death in developed countries. Cisplatin is one of the most chemotherapeutic drug. In spite of its great efficacy, it shows several side effects and most patients develop a resistance to cisplatin. To overcome the cisplatin resistance, drugs are often administered in combination in order to exploit the drug synergy. After discovery of cisplatin, the research focused on metal complexes less toxic, more effective and that exploit synergistic effect when used in combination. In this work I studied new copper, zinc and vanadium complexes with biological activity. I tested in vitro the studied compounds alone and in combination with drug currently in use against a panel of wild type tumour cell lines and their cisplatin-resistant sublines. I applied chemometric tools such as experimental design (ED) and artificial neural networks (ANNs) to the biochemical data collected. Finally, I used the artificial neural networks to evaluate the cell culture cross-contamination. I selected a new family of copper(II) complexes with 1,10-phenanthroline (phen), 1,10-phenanthrolin-5,6-dione (phendione), and 1,10-phenanthrolin-5,6-diol (phendiol) for the synthesis of new antiproliferative agents. Considering that the DNA is an important target for several cytotoxic metal complexes, I studied the interaction of these Cu(II) complexes with DNA. I tested the ligands and complexes against normal and tumour derived human cell lines. I tested combinations of the studied complexes and cisplatin for their potential synergistic effect against a panel of wild type tumour cell lines and their cisplatin-resistant sublines. I evaluated the selectivity of drug combinations testing the compounds also against ex vivo cultures of human normal cell lines. Considering that the synergy may arise from a chemical reaction among the drugs, I studied the possible formation of new adducts between cisplatin, copper(II) complexes and glutathione. I studied the phospholipid profile of wild type human cancer cell lines and their cisplatin-resistant sublines, given that changes in lipid composition and distribution on the cell membranes have been observed in cancer cells. The in vitro cultured cell lines are widely used as model in biomedical research and the cross-contamination of cell lines represents a highly relevant problem. The ex-post discovery of erroneous results and conclusions led to paper retraction and many high-impact journals started to adopt a zero-tolerance policy requiring confirmation of cell line identity as prerequisite for publication. On the base of these considerations, I decided to develop and validate a method for evaluation of cell culture cross-contamination. I also studied zinc and vanadium complexes. Zinc is an essential metal ion involved in a wide variety of biological processes and several proteins bind zinc for their proper functioning. I studied zinc complexes with the drug methimazole (MeImHS) and its anion (MeImS) in order to provide information for the structure prediction and reactivity of Zn-metalloproteins and -metalloenzymes. Vanadium plays a number of roles in biological systems and vanadocene dichloride was the first discovered vanadium species with antitumour activity. Considering that the mechanism of the anticancer agent vanadocene dichloride is closely related to the biotransformation in the blood plasma, I studied the speciation of vanadocene dichloride in the plasma under physiological conditions. In order to prepare new metal complexes, I also synthesized and characterized a new group of Schiff base ligands derived from salicyladehyde and six natural amino acids. For the analysis of the collected data, I used the ED to set up the experiments for the evaluation of the synergistic effect of drug combinations, and for the study of the possible formation of new adducts between cisplatin, glutathione and studied complexes. I used ANNs for predict and quantify the synergism of drugs, and for the evaluation of cell culture cross-contamination levels.