Design, Synthesis, and In Vitro Cytotoxicity Studies of 1H-Benzimidazol-2-yl–Enaminone Hybrids as Tubulin Polymerization Inhibitors

Abstract

Tubulin polymerization inhibitors play a pivotal role in cancer therapy due to their ability to disrupt microtubule dynamics, which are essential for mitotic cell division. Taking this into consideration, a series of novel 1H-benzimidazol-2-yl–enaminone hybrids were designed and synthesized to explore their potential as tubulin polymerization inhibitors. In vitro assays demonstrated that (2E)-1-(1-ethyl-1H-benzimidazol-2-yl)-3-pyrrolidin-1-ylprop-2-en-1-one displayed significant cytotoxic effects against various cancer cell lines, with a low IC₅₀ value of 5.18 ± 1.07 μM for the HCT-116 cell line, compared with that of the standard drug paclitaxel (20.32 ± 1.18 μM). This hybrid selectively targeted cancer cells over nonmalignant cells, inducing apoptosis. Our findings highlighted the potential of this derivative to inhibit the G2/M phase of the cell cycle. The compound also demonstrated tubulin inhibition, establishing itself as a promising lead candidate for anticancer therapy and paving the way for the development of more-effective tubulin-targeting agents in drug discovery.

Key words

tubulin polymerization inhibitors - anticancer drugs - benzimidazoles - enaminones - cytotoxicity - apoptosis

Publikationsverlauf

Eingereicht: 15. Februar 2025

Angenommen nach Revision: 28. April 2025

Artikel online veröffentlicht:
03. Juni 2025

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• 26 Benzimidazol-2-yl Enaminone Derivatives 8a–l; General Procedure Compound 6a or 6b (1 mmol) was treated with the appropriate substituted secondary amine 7a–g (0.5 mmol) in the presence of Ag₂CO₃ (0.15 mmol) in H₂O (5 mL) at 40 °C for 3–4 h under air. When the reaction was complete, the mixture was filtered under vacuum, and the filtrate was extracted with EtOAc. The organic layer was concentrated, and the resulting crude product was purified by column chromatography [silica gel (100–200 mesh)]. (2E)-1-(1-Ethyl-1H-benzimidazol-2-yl)-3-morpholin-4-ylprop-2-en-1-one (8a) Yellow solid; yield: 85%; mp 163–165 °C. FTIR: 1934, 1634, 1552, 1443, 1356, 1235, 1173, 888, 747 cm^–1. ¹H NMR (500 MHz, DMSO-d ₆): δ = 7.88 (d, J = 7.9 Hz, 1 H), 7.82 (d, J = 12.8 Hz, 1 H), 7.46 (d, J = 7.9 Hz, 1 H), 7.41–7.33 (m, 2 H), 6.62 (d, J = 11.2 Hz, 1 H), 4.75 (q, J = 7.1 Hz, 2 H), 3.81–3.74 (m, 4 H), 3.51–3.49 (m, 4 H), 1.49 (t, J = 7.1 Hz, 3 H). ¹³C NMR (125 MHz, DMSO-d ₆): δ = 180.4, 153.2, 148.8, 141.8, 136.0, 124.5, 123.1, 120.8, 111.3, 93.9, 66.8, 65.7, 53.2, 46.2, 16.0. HRMS (ESI): m/z [M + H]⁺ calcd for C₁₆H₂₀N₃O₂: 286.1556; found: 286.1558.