A large group of aminoalkyl and aminoalkanol derivatives of selected dicarboximides were synthesized and characterized by 1HNMR, 13CNMR and ESI MS spectra analysis. The thirty nine new compounds were tested for their cytotoxic properties in human chronic (K562), acute leukemia (HL-60), and cervical cancer cells (HeLa) as well as in normal endothelial cells (HUVEC). The most promising compounds are 4-[2-(dimethylamino)ethyl]-, (diethylamino) ethyl]-, 4-[2-(piperidin-1-yl)ethyl]-, 4-[3-(dimethylamino)propyl]- and 4-[2-hydroxy-3-(propan- 2-ylamino)propyl]- derivatives of 1,7-diethyl-8,9-diphenyl-4-azatricyclo[5.2.1.0(2,6)]dec-8-ene-3,5,10-trione exhibiting high and selective cytotoxicity towards K562 and HL-60 cells (IC50 in the range of 1-10 µM) while being non-toxic towards HUVEC and HeLa cells (IC50> 100 μM). Moreover, the preliminary studies have showed that 4-[2-(piperidin-1-yl)ethyl]- 1,7-diethyl-8,9-diphenyl-4-azatricyclo [5.2.1.0(2,6)]dec-8-ene-3,5,10-trione induces programmed cell death (apoptosis) in leukemia cells.

The results of our previous research indicated that some derivatives of benzofurans, particularly halogeno-derivatives, are selectively toxic towards human leukemia cells. Continuing our work with this group of compounds we here report new data on the synthesis as well as regarding the physico-chemical and biological characterization of fourteen new derivatives of benzofurans, including six brominated compounds. The structures of all new compounds were established by spectroscopic methods (1H- and, 13C-NMR, ESI MS), and elemental analyses. Their cytotoxicity was evaluated against K562 (leukemia), MOLT-4 (leukemia), HeLa (cervix carcinoma), and normal cells (HUVEC). Five compounds (1c, 1e, 2d, 3a, 3d) showed significant cytotoxic activity against all tested cell lines and selectivity for cancer cell lines. The SAR analysis (structure-activity relationship analysis) indicated that the presence of bromine introduced to a methyl or acetyl group that was attached to the benzofuran system increased their cytotoxicity both in normal and cancer cells.

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We identified novel dicarboximides that were selectively cytotoxic towards human leukemia cells. Using chemical and biological methods, we characterized the biological activity, identified cellular protein targets and defined the mechanism of action of the test dicarboximides. The reported IC50 values (concentration required to reduce cell survival fraction to 50% of control) of selected dicarboximides were similar or lower than IC50 of registered anticancer drugs, for example cytarabine, sorafenib, irinotecan. Test compounds induced apoptosis in chronic myelogenous (K562) and acute lymphoblastic (MOLT-4) leukemia cells by activation of receptor and mitochondrial apoptotic pathways and increased the expression of proapoptotic genes (BAX, NOXA, HTRA2, TNFRSF10B, ESRRBL1). Selected dicarboximides displayed immunomodulatory activity and downregulated IKZF1 and IKZF3 transcription factors in K562 and MOLT-4 leukemia cells. ATP-binding cassette protein 50 (ABC50) was identified as a target for dicarboximides. Cancer cells with knocked down ABC50 showed increased resistance to dicarboximides. Based on the structure of dicarboximides and thalidomide, novel proteolysis-targeting chimeras (PROTACs) were synthesized and used as tools to downregulate ABC50 in leukemia cells.

Two aminoalkanol derivatives of 1,7-diEthyl-8,9-diphenyl-4azatricyclo (5.2.1.02,6) dec-8-ene-3,5,10-trione and two derivatives of 1,7-diMethyl-8,9-diphenyl-4-azatricyclo (5.2.1.02.6) dec-8-ene-3,5,10-trione were evaluated in vitro for their inhibition efficacy of acetylcholinesterase. The Km, Vmax, slope angles of Lineweaver–Burk plots, Ki and IC50 values showed that all four aminoalkanol derivatives are competitive inhibitors of acetylcholinesterase whose inhibitory potency depends, to a varying extent, on the nature of the four different substituents present in the main compound structure. Studies have shown that the most potent acetylcholinesterase inhibitors are derivatives containing isopropylamine and/or methyl substituents in their structure. In contrast, dimethylamine and/or ethyl substituents seem to have a weaker, albeit visible, effect on the inhibitory potency of acetylcholinesterase. Additionally, docking studies suggest that studied compounds binds with the peripheral anionic site and not enter into the catalytic pocket due to the presence of the sterically extended substituent.