In the master’s thesis, we have been developing new cathepsin B inhibitors. The work consisted of design, synthesis and testing of beforementioned inhibitors. Enzyme cathepsin B has exopeptidase and endopeptidase activity. The first one is involved in important physiological functions, whereas the second is connected to the pathological conditions. In recent studies, an established active pharmaceutical ingredient nitroxoline has been shown as the inhibitor of cathepsin’s B endopeptidase activity. An overview of recent research shows on discovery of improved nitroxoline inhibitor of cathepsin B. This inhibitor has an electrophilic side chain in the position 7 of nitroxoline. In the master’s thesis, we have been searching for new 7- and/or 8-substituted nitroxoline’s derivatives, which could inhibit cathepsin’s B endopeptidase activity. The new compounds were designed, using molecular docking Schrödinger program package in the initial phase of development. Designed inhibitors mostly included in the structure of the molecule mildly electrophilic part, which could covalently bind to the amino acid residue Cys29 in the active site of the enzyme. The results of molecular docking were ranked by the values of Glide Score and MM-GBSA dG Bind. The results have been compared to the results of reference compounds, i.e. nitroxoline and improved nitroxoline’s inhibitor. In the second phase of the development, 13 compounds with most promised results were synthesised and characterised. Most of the compounds have been synthesised through the Suzuki-Miyaura coupling reaction, where trifluoroborates and boronate esters have been used as reagents. In the end, the designed inhibitory properties of synthesised compounds have been tested with the enzyme tests. We have been observing the kinetics of the enzyme conversion of an appropriate substrate by measuring fluorecence. Firstly, the potent inhibitory properties in terms of human cathepsin’s B endopeptidase activity have been observed through preliminary tests. Afterwards, the normalised IC50 values of compounds have been determined with titration curves using the GraphPad Prism program. The IC50 value of the reference compound nitroxoline has also been determined. The IC50 values of seven compounds were much lower than the IC50 value of the reference nitroxoline. In the master’s thesis also preliminary tests of human cathepsin’s L endopeptidase activity inhibition have been performed to check the selectivity of synthesised potent inhibitors.
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