Cancer is a group of diseases in which there is uncontrolled growth of tissue cells, regardless of the needs of the body. Cancer has been a major global health challenge for decades. With a better understanding of the disease, new treatment approaches have been developed to achieve better treatment outcomes. Established treatment approaches include agents that target human DNA topoisomerase II (topo II). Topo II is an enzyme involved in releasing and introducing topological changes in the DNA molecule. In humans, there are two isoforms of the enzyme – IIα and IIβ. The first is found in high concentrations in rapidly dividing cells, including cancer cells, while the other is found in all cells in the nucleus. Therefore, in development of anticancer agents, we aim for selectivity for the IIα isoform. Agents that inhibit topoisomerase II cause improper DNA replication, which in turn leads to cell apoptosis. In practice, a group of agents known as topoisomerase poisons are currently used for this purpose. Topoisomerase poisons are effective in the treatment of several forms of cancer, e.g. leukaemia, lymphoma, sarcoma, etc. Side effects may occur with their use including cardiotoxicity and the formation of secondary forms of cancer. Another group of agents that act on this enzyme are catalytic inhibitors. These can target several different receptors on the enzyme. The most promising are those that act at the ATP binding site. Our goal was to synthesize three analogues of known topoisomerase II inhibitors that act at the ATP binding site. Known inhibitors contain N-phenylpyrrolamide in their structure. We attached an additional methyl group to the nitrogen atom of N-phenylpyrrolamide and investigated how this affects the activity of the compounds and how high the activity is compared to the original compounds. We confirmed the structure of the synthesized compounds, determined their physicochemical properties by spectroscopic methods (nuclear magnetic resonance, infrared spectroscopy, mass spectrometry) and characterized them accordingly, and determined their purity using chromatographic methods (thin-layer and column chromatography, high-resolution liquid chromatography). The inhibitory effect was evaluated on bacterial topoisomerase - DNA gyrase of the E. coli bacterium. This enzyme has a similar ATP binding domain structure as human DNA topoisomerase IIα.
The mean inhibitory concentration (IC50) was determined. The final synthesized compounds (8, 18 and 27) showed lower inhibitory activity compared to the unmethylated analogues. The methyl group may hinder the formation of hydrogen bonds between the amide group and the enzyme.
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