A series of 4-thiomorpholinophenyl-thiosemicarbazones as cholinesterase inhibitors with anti-neuroblastoma effects

Abstract

A novel series of 4-thiomorpholinophenyl-thiosemicarbazones (3a-p) was synthesized and characterized by spectroscopic techniques. The compounds were evaluated for inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), key enzymes associated with neurodegenerative disorders. All derivatives exhibited potent inhibition, with nanomolar IC50 values ranging from 11.36 to 34.17 nM (AChE) and 33.42 to 79.77 nM (BChE), comparable to standard drugs galantamine and tacrine. Compound 3l, bearing a benzyl group, showed the strongest dual inhibition (AChE IC50 = 11.36 nM) and compound 3n exhibited the highest BChE selectivity (K-i = 33.42 +/- 2.38 nM). Anticancer activity was assessed against SH-SY5Y neuroblastoma and HEK-293 cell lines. Compound 3l demonstrated selective cytotoxicity against SH-SY5Y cells (IC50 = 21.11 +/- 0.42 mu M) with minimal toxicity toward HEK-293 cells (IC50 = 69.49 +/- 4.27 mu M, SI = 3.3), comparable to sorafenib. Molecular docking showed multiple pi-pi and hydrogen-bond interactions of 3l with AChE (Tyr-72, Tyr-337, Trp-286, His-447, Phe-295, Tyr-124) and 3n with BChE (Trp-231, Phe-329, Pro-285, Gln-119, Thr-120). MM-GBSA calculations indicated favorable binding energies (-70.74 and - 67.09 kcal/mol) driven by van der Waals and lipophilic forces. Molecular dynamics simulations confirmed stable complexes with RMSD similar to 1.4 & Aring; for ligands, similar to 2.0 & Aring; for proteins, persistent interactions, and reduced flexibility (RMSF similar to 1.5 & Aring;). ADME analysis suggested acceptable drug-like properties. These results highlight 3l and 3n as promising scaffolds for dual cholinesterase inhibition and selective anticancer activity.