Biological evaluation of novel 5-((1H-indol-3-yl) methyl)-2-(4-chlorobenzyl)-6-phenyl-imidazo[2,1-b][13,4]thiadiazole derivatives as novel BCL-2 specific inhibitors

Antiapoptotic protein BCL2 is known to be upregulated in several cancer cells and therefore, it is an excellent target for cancer therapy. Previously, we reported a novel BCL2 inhibitor, Disarib, which inhibited BCL2 by predominantly binding to its BH1 domain and exhibited platelet-sparing ability like ABT199, the only FDA-approved BCL2 inhibitor. Here, we have synthesized the novel Disarib derivatives where oxindole moiety in Disarib was replaced with indole and evaluated their biological activity. We report several derivatives of Disarib and the identification of DSR 43 and 4-OCH₃, as the most potent among them. Treatment of cancer cell lines with the Disarib derivatives, DSR 43 and 4-OCH₃ led to the activation of the apoptotic pathway without generating any ROS or disrupting the mitochondrial membrane potential within the cells, leading to cell death. Western blot analysis in tandem with Annexin V/PI staining confirmed the activation of apoptosis. In silico studies, using derivatives suggests a promising therapeutic window with less off-target effects. Furthermore, their efficacy across different cancer cell lines highlights their broad potential as anticancer agents. Taken together, our results suggest that Disarib derivatives may have the potential to be developed as cancer therapeutic.