Design, synthesis and biological evaluation of novel substituted pyrazole-hydrazine hybrids as potent and safe anti-leukemia agents

Inspired by the structural motifs of Selinexor, a series of novel pyrazole-hydrazine hybrids were rationally designed and synthesized as potential reversible Exportin-1 (XPO1) inhibitors for the treatment of leukemia. The design strategy deliberately excluded the covalent warhead of Selinexor, aiming to achieve potent anti-leukemic activity through high-affinity, non-covalent interactions. Among the synthesized compounds, 5–33 was identified as the most potent candidate, demonstrating superior in vitro anti-leukemic activity against Jurkat, K562, and CMK cell lines (IC₅₀ values of 0.41, 1.01, and 0.88 μM, respectively), outperforming the positive controls Selinexor and cisplatin. Crucially, all hybrids exhibited significantly lower hepatotoxicity than cisplatin. Structure-activity relationship (SAR) studies revealed that strong electron-withdrawing trifluoromethyl groups on the pyridine ring and an electron-donating para -methoxyl group on the benzene ring were critical for potency. This was further rationalized by conceptual DFT calculations, where 5–33 displayed the most reactive electronic profile, characterized by the narrowest HOMO-LUMO gap and highest electrophilicity index. Molecular docking confirmed that 5–33 binds strongly to the XPO1 active site (-4.61 kcal/mol) via superior shape complementarity and an extensive non-covalent interaction network, aligning with the design of a reversible inhibitor. Molecular dynamics simulations further substantiated the stability of this non-covalent complex, demonstrating sustained key interactions and a high binding free energy (-33.90 kcal/mol). This study identifies 5–33 as a promising, safe, and potent lead compound for developing next-generation anti-leukemia therapeutics.