Organoselenium-containing monastrol analogs show preferential antileukemic activity and distinct cellular responses...

Selenium-containing dihydropyrimidinones (DHPMs) have emerged as promising scaffolds for anticancer drug development owing to their structural versatility and ability to modulate biologically relevant targets. Here, we investigated the antileukemic activity of two previously reported selenium-containing monastrol analogs, 4b¹ and 4d¹, and explored their interaction with kinesin Eg5 using complementary cellular, biophysical, and computational approaches. Cytotoxicity was evaluated by MTT assay in tumor and non-tumor cell lines, followed by selectivity index determination. Cell-cycle distribution and apoptosis were analyzed by flow cytometry, morphological alterations by panoptic staining, and protein-ligand interactions by molecular docking and differential scanning fluorimetry (DSF). Both compounds displayed preferential cytotoxic activity toward AML cells within the tested concentration range, with MOLM-13 being the most sensitive cell line. 4b¹ and 4d¹ exhibited IC₅₀ values of 9.35 μM and 6.96 μM, respectively, while showing limited toxicity toward non-tumoral cells. Their antiproliferative effects were time-dependent and associated with distinct cellular responses: 4b¹ induced G₂/M arrest accompanied by pronounced apoptosis, whereas 4d¹ promoted G₀/G₁ accumulation with a more moderate apoptotic response. These findings were supported by morphological features consistent with apoptotic cell death. Molecular docking revealed that both analogs adopted predicted binding modes that were broadly consistent with the canonical binding orientation of monastrol within the Eg5 allosteric pocket, while DSF demonstrated ligand-induced thermal destabilization, providing experimental evidence consistent with ligand engagement of Eg5. Collectively, this study integrates cellular, biophysical, and computational evidence to demonstrate that selenium-containing monastrol analogs exhibit preferential cytotoxic activity toward AML cells and distinct biological responses, with findings consistent with engagement of the kinesin Eg5 allosteric site, supporting their potential as lead compounds for the development of novel therapies against acute myeloid leukemia.