Trifluoromethyl-Benzimidazole-Hydrazone Derivatives as Promising Selective Anticancer Agents: Synthesis,...

Background/Objectives: Benzimidazole and hydrazone scaffolds are widely investigated in anticancer drug discovery because of their structural versatility and capacity to interact with multiple cancer-related targets. This study aimed to synthesize a series of trifluoromethyl-substituted benzimidazole-hydrazone derivatives, evaluate their antiproliferative activity and cancer-cell selectivity, and explore their potential interactions with breast cancer-associated molecular targets. Methods: A series of benzimidazole-hydrazone derivatives were prepared through a four-step synthetic route using both conventional and microwave-assisted procedures. The structures of the synthesized compounds were characterized using spectroscopic and analytical methods. Antiproliferative activity was evaluated in estrogen receptor-positive MCF-7 human breast cancer cells using the MTT assay after 48 h of exposure. Selected active compounds were additionally tested against non-tumorigenic hTERT cells to determine their selectivity indices. In silico analyses were performed against estrogen receptor alpha in antagonist and selective estrogen receptor degrader conformations, bromodomain-containing protein 4, and the mTOR kinase domain. Results: Microwave irradiation substantially reduced reaction times from 12-24 h to 4-6 min and increased isolated yields by 7-24 percentage points compared with conventional conditions. Compounds 4, 7, 9, and 11 reduced MCF-7 cell viability below 50% at 20 μM. Compound 7 showed the highest antiproliferative activity, with an IC₅₀ value of 7.5 ± 0.8 μM, and the greatest selectivity toward MCF-7 cells over hTERT cells, with a selectivity index of 12.66. Molecular docking, MD simulation, and MM/GBSA calculations predicted that compound 7 would effectively bind to the investigated targets, particularly estrogen receptor alpha, as well as the BRD4 and mTOR kinase domains. Conclusions: Compound 7 represents a selective, mid-micromolar benzimidazole-hydrazone lead against MCF-7 breast cancer cells. Its predicted molecular interactions warrant further target-based, mechanistic, pharmacokinetic, and in vivo evaluation.