Synthesis and evaluation of iridium(III) complexes on antineoplastic activity against human gastric carcinoma SGC-7901 cells

Synthesis, characterization, anticancer efficacy evaluation of ruthenium(II) and iridium(III) polypyridyl complexes toward A549 cells

A new ligand DFIP (2-(dibenzo[b,d]furan-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) and its two complexes iridium(III) [Ir(ppy)₂(DFIP)](PF₆) (ppy = 2-phenylpyridine, Ir1) and ruthenium(II) [Ru(bpy)₂(DFIP)](PF₆)₂ (bpy = 2,2'-bipyridine, Ru1) were synthesized and characterized. The anticancer effects of the two complexes on A549, BEL-7402, HepG2, SGC-7901, HCT116 and normal LO2 cells were tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Complex Ir1 shows high cytotoxic activity on A549, BEL-7402, SGC-7901 and HepG2, Ru1 exhibits moderate anticancer activity toward A549, BEL-7402 and SGC-7901 cells. The IC₅₀ values of Ir1 and Ru1 toward A549 are 7.2 ± 0.1 and 22.6 ± 1.4 μM, respectively. The localization of complexes Ir1 and Ru1 in the mitochondrial, intracellular accumulation of reactive oxygen species (ROS) levels, and the changes of mitochondrial membrane potential (MMP) and cytochrome c (cyto-c) were investigated. Apoptosis and cell cycle were detected by flow cytometry. Immunogenic cell death (ICD) was used to detect the effects of Ir1 and Ru1 on the A549 using a confocal laser scanning microscope. The expression of apoptosis-related proteins was detected by western blotting. Ir1 and Ru1 can increase the intracellular ROS levels and release cyto-c, reduce the MMP, leading to the apoptosis of A549 cells and blocking the A549 cells at the G0/G1 phase. Additionally, the complexes caused a decrease of the expression of polyADP-ribose polymerase (PARP), caspase 3, Bcl-2 (B-cell lymphoma-2), PI3K (phosphoinositide-3 kinase) and upregulated the expression of Bax. All these findings indicated that the complexes exert anticancer efficacy to induce cell death through immunogenic cell death, apoptosis, and autophagy.

Anticancer effect evaluation of iridium(III) complexes targeting mitochondria and endoplasmic reticulum

Ligand HMSPIP (2-(4-(methylsulfonyl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline) and its iridium(III) complexes [Ir(ppy)₂(HMSPIP)]PF₆ (ppy = 2-phenylpyridine, Ir1) and [Ir(bzq)₂(HMSPIP)]PF₆ (bzq = benzo[h]quinoline, Ir2) were synthesized. The complexes were characterized by ¹H NMR, ¹³C NMR, and UV/Vis spectra. The cytotoxicity of the complexes toward cancer cells were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method, the scratch wound healing and colony-forming were also investigated. MTT assay certificated that the complexes show high toxic effect on the HeLa cells. The cell cycle assay illustrated that the complexes blocked cell growth at G₀/G₁ phase in HeLa cells. A series of subsequent experiments showed that the complexes first enter the endoplasmic reticulum (ER) and then enter the mitochondria, leading to an increase in intracellular Ca²⁺ and reactive oxygen species (ROS) content, depolarizing mitochondrial membrane potential (MMP), and ultimately resulting in apoptosis. In addition, the experimental results revealed that the complexes not only increase the level of ROS but also inhibit the production of GSH and eventually produce large amounts of MDA and further leading to cell death. Taken together, we consider that the complexes can be used as potential candidate drugs for HeLa cancer treatment.

Synthesis, Characterization and Anticancer Efficacy Studies of Iridium (III) Polypyridyl Complexes against Colon Cancer HCT116 Cells

In this paper, two new iridium (III) complexes, [Ir(ppy)2(ipbp)](PF6) (Ir1) (ppy = 2-phenylpyridine, ipbp = 3-(1H-imidazo[4,5-f][1,10]phenanthrolin-2yl)-4H-chromen-4-one) and [Ir(bzq)2(ipbp)](PF6) (Ir2) (bzq = benzo[h]quinolone), were synthesized and characterized. The cytotoxicity of the complexes against human colon cancer HCT116 and normal LO2 cells was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. The complexes Ir1 and Ir2 show high cytotoxic efficacy toward HCT116 cells with a low IC50 value of 1.75 ± 0.10 and 6.12 ± 0.2 µM. Interestingly, Ir1 only kills cancer cells, not normal LO2 cells (IC50 > 200 µM). The inhibition of cell proliferation and migration were investigated by multiple tumor spheroid (3D) and wound healing experiments. The cellular uptake was explored under a fluorescence microscope. The intracellular reactive oxygen species (ROS), change of mitochondrial membrane potential, glutathione (GSH) and adenine nucleoside triphosphate (ATP) were studied. Apoptosis and cell cycle arrest were performed by flow cytometry. The results show that the complexes induce early apoptosis and inhibit the cell proliferation at the G0/G1 phase. Additionally, the apoptotic mechanism was researched by Western blot analysis. The results obtained demonstrate that the complexes cause apoptosis in HCT116 cells through ROS-mediated mitochondrial dysfunction and the inhibition of PI3K/AKT signaling pathways.