Development of novel inhibitors targeting the tumour-related carbonic anhydrase isoforms and of small molecule ligands targeting the human tyrosinase and tyrosinase related protein 1

This Thesis is focused on the development of novel inhibitors targeting the tumour-related carbonic anhydrase isoforms and on the development of small molecule ligands targeting the human tyrosinase and tyrosinase related protein 1. The carbonic anhydrases (CAs) are a superfamily of metalloenzymes that catalyse the reversible hydration of carbon dioxide (CO2) into bicarbonate (HCO3-) and protons (H+). The human CAs (hCAs), belonging to the α family, are involved in several functions and pathological conditions. Particularly, hCA IX and hCA XII, known as tumour-related isoforms, are selectively upregulated in solid tumours. Though a large number of inhibitors have been developed to date, only two of them are currently in clinical trials highlighting the urgent need of novel and selective inhibitors targeting hCA IX and hCA XII. Thus, the aim of the project was the design, synthesis and SAR analysis of two libraries of compounds based on the 2-(benzylsulfinyl)benzoic acid scaffold and on the saccharin and acesulfame nucleus. Considering the first library of compounds, the chemical modifications attempted on the 2-(benzylthio)benzamide, obtained after a lead optimization of the 2-(benzylsulfinyl)benzoic acid , led to 15 derivatives that appeared to be effective exclusively against hCA IX, though less active than their lead compound. Considering the second library of compounds, the different strategies applied on the saccharin and acesulfame scaffold led to 60 derivatives that exhibited different inhibitory profile mostly related to the presence of moieties of conformational freedom. The molecular modelling studies proposed as inhibition mechanism the anchoring to zinc-bound water molecule. Human tyrosinase (hTYR) and tyrosinase-related protein 1 (TYRP1) are closely related proteins involved in the synthesis of melanin and selectively upregulated in melanoma. Thus, the aim of the project was to develop and evaluate small molecule ligands specific to hTYR and TYRP1 using previously collected data elaborated from the DNA encoded chemical libraries (DELs) and the multivalent approach applied to an alkyne derivative of Thiamidol™. The ligands identified from the DELs after a screening performed on hTYR and TYRP1 resulted active in the micromolar range. The multimerization of an alkyne derivative of Thiamidol™ led to multimeric structures of different valence. among them the tetrameric structure showed the best binding profile though worse than the one of the TA99, a murine antibody targeting TYRP1.