• emphysema
• zbg
• Metalloproteinases
• copd

Matrix metalloproteinases (MMPs) constitute a family of more than 20 structurally and functionally related enzymes which are involved in tissue remodelling and wounds healing . Among these, the gelatinases MMP-2, and -9 and the macrophage elastase MMP-12 have a fundamental role in the development of different and relevant pathologies. MMP-12 is mainly produced by macrophages and it seems to be involved in acute and chronic pulmonary inflammatory diseases associated with intense airway remodelling, such as chronic obstructive pulmonary disease (COPD) and emphysema . In fact, MMP-12 is able to degrade different extracellular matrix components, among which is elastin, the major constituents of alveolar walls. MMP-2 and MMP-9 are particularly involved in cancer pathogenesis and progression. These enzymes readily digest type IV collagen, one of the main constituents of basement membrane (BM). Thanks to its strong architecture, basement membrane prevents migration of cells in physiological conditions. In pathological settings, when control on these MMPs is lost, the degradation of BM increases, allowing tumour cells to migrate. This process facilitates metastasis dispersion and angiogenesis .
On these basis, MMP-2, -9 and -12 can be considered attractive targets to study selective inhibitors useful in the development of new therapies for lung diseases and cancer.
Zinc ion is present at the active site of MMPs and is a biologically relevant first-row transition M2+ metal ion. The vast majority of MMP inhibitors developed so far consisted of small molecules that chelated the active site zinc through a zinc-binding group (ZBG) such as hydroxamic acid. The design of ligands with high selectivity for this metallic cofactor is important to avoid off-target toxicity due to chelation of other metal cofactors present in the body.
Starting from arylsulfones 1 and 2, already published as potent inhibitors of MMP-12, MMP-9 and MMP-2, in my Thesis project I carried out the optimization of these scaffolds to improve activity and selectivity.
In particular, I synthesized new derivatives bearing ZBGs alternative to the hydroxamic acid in order to overcome the potential poor stability of this ZBG in vivo. The hydroxamate group leads to the generation of very good inhibitors in terms of potency and affinity but, as reported in some clinical trials with hydroxamate-based inhibitors, this ZBG seems to be problematic in terms of cytotoxicity and bioavailability. In fact, in those cases it has shown poor metabolic stability being hydrolyzed in hydroxylamine (a cytotoxic agent) and into the corresponding carboxylic acid (often less potent and with different profiles of bioavailability and selectivity with respect to the starting hydroxamate). Furthermore, I modified the oxidation state of the sulfur atom in the thioaryl scaffold substituting the sulfone group with a sulfide group to evaluate the role of the oxidation state on potency and selectivity in strictly related structural analogues.
All these new compounds were tested on human recombinant MMP-12, -2 and -9 by fluorometric assay to evaluate their inhibitory activity in vitro.
Moreover, with the aim to confirm their zinc chelating properties, these compounds were studied in their equilibria of complex formation with Zn(II) using by potentiometric techniques. Finally, the new complexes zinc/ligand were also clarified by NMR spectroscopy.