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Updated: May 29, 2025
Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents
Published on: May 28, 2014
Enhanced Anticancer Selectivity of Cyclometalated Imidazole/Pyrazole-Imine IridiumIII Complexes Through the Switch
Zhe Liu1, Kangning Lai1, Pengwei Li1
1Key Laboratory of Life-Organic Analysis of Shandong Province, Key Laboratory of Green Natural Products and Pharmaceutical Intermediates in Colleges and Universities of Shandong Province, School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China.
Abstract:
Cyclometalated iridiumIII complexes have shown promising anticancer properties, with variations in charge and ligand substitution significantly influencing their biological activity. However, zwitterionic iridiumIII complexes remain scarcely explored. Herein, we report a series of zwitterionic cyclometalated imidazole/pyrazole-imine iridiumIII complexes and compare their biological activity to analogous cationic complexes with sulfonate counteranions. X-ray crystallography confirmed the structural differences between the cationic and zwitterionic forms. These complexes exhibited cytotoxicity against A549, HeLa, and HepG2 cancer cells, with IC50 values ranging from 14.35 to 69.12 μM. While cationic complexes showed higher cytotoxicity, zwitterionic complexes demonstrated enhanced selectivity for A549 cancer cells over BEAS-2B normal cells (selectivity index: 3.72-5.90 for zwitterionic forms vs 1.16-1.44 for cationic forms). This selectivity is attributed to distinct cellular uptake mechanisms: zwitterionic complexes use an energy-dependent pathway in cancer cells and an energy-independent pathway in normal cells, leading to differences in cellular accumulation and redox activity. Mechanistic studies revealed that both complex types induce ROS generation and mitochondrial membrane depolarization (MMP), with apoptosis as the primary cell death pathway.
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