Design and anticancer behaviour of cationic/neutral half-sandwich iridium(III) imidazole-phenanthroline/phenanthrene complexes

Considerable attention has been devoted to the exploration of organometallic iridium(III) (IrIII) complexes for their potential as metallic anticancer drugs. In this study, twelve half-sandwich IrIII imidazole-phenanthroline/phenanthrene complexes were prepared and characterized. Complexes exhibited promising in-vitro anti-proliferative activity, and some are obviously superior to cisplatin towards A549 cells. These complexes possessed suitable fluorescence, and a non-energy-dependent uptake pathway was identified, subsequently leading to their accumulation in the lysosome and the lysosomal damage. Additionally, complexes could inhibit the cell cycle (G1-phase) and catalyze intracellular NADH oxidation, thus substantiating the elevation of intracellular reactive oxygen species (ROS) level, which confirming the oxidative mechanism. Western blotting further confirmed that complexes could induce A549 cell apoptosis through the lysosomal-mitochondrial anticancer pathway, which was inconsistent with cisplatin. In summary, these complexes offer fresh concepts for the development of organometallic non‑platinum anticancer drugs.

Hook, Line, and Sinker! Spectroscopic Studies of Bi-Modular Mono- and Bis-1,8-naphthalimide-Ru(bpy)3-conjugates as DNA "Light Switches"

Bi-chromophoric ruthenium polypyridyl complexes comprising one or two nitro-1,8-naphthalimide groups are shown to be effective DNA binders with off-on light switching properties. The binding to DNA was investigated using a combination of studies such as UV-visible absorption and emission titrations, thermal denaturation, and circular dichroism spectroscopy. The DNA affinity was shown to be sensitive to both the linker length and the number of naphthalimides (one vs two) contained in these systems and binding constants ranging from 10⁶ to 10⁷ M^-1 for salmon testes DNA. The strong DNA binding is attributed to the combination of naphthalimide intercalation and the electrostatic interaction of the ruthenium complex. Large emission enhancements from the metal to ligand charge transfer (MLCT) emission arising from the metal complex were observed upon DNA binding, which was attributed to the interruption of intramolecular electron transfer quenching processes. Moving the nitro substitution from the 4-position to the 3-position is found to result in modification of the DNA binding and the resulting optical properties. The off-on light switch phenomena reported demonstrate the potential of these complexes to act as DNA probes.

A fundamental role of solvent polarity and remote substitution of 2-(4-R-phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline framework in controlling of ground- and excited-state properties of Re(I) chromophores [ReCl(CO)3(R-C6H4-imphen)]

A series of Re(I) carbonyl chromophores with 1H-imidazo[4,5-f][1,10]phenanthroline (imphen) ligand functionalized with electron-donating amine groups attached to the imidazole ring via phenylene linkage was designed to investigate the impact of...

DNA binding, antitubercular, antibacterial and anticancer studies of newly designed piano-stool ruthenium(ii) complexes

The chemotherapeutic potential of ruthenium(ii) complexes as DNA binding, antitubercular, antibacterial, and anticancer agents.

Cytotoxicity evaluation and DNA interaction of RuII-bipy complexes containing coumarin-based ligands

Although there are various treatment options for cancer, this disease still has caused an increasing number of deaths, demanding more efficient, selective and less harmful drugs. Several classes of ruthenium compounds have been investigated as metallodrugs for cancer, mainly after the entry of imidazolH [trans-RuCl4-(DMSO-S)(imidazole)] (NAMI-A) and indazolH [trans-RuCl4-(Indazol)2] (KP1019) in clinical trials. In this sense, RuII complexes with general formula [Ru(L1-3)(bipy)2]PF6 (1-3) (L1 = ethyl 3-(6-methyl-2-oxo-2H-chromen-3-yl)-3-oxopropanoate, L2 = ethyl 3-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)-3-oxopropanoate, L3 = ethyl 3-(8-methoxy-2-oxo-2H-chromen-3-yl)-3-oxopropanoate and bipy = bipyridine) have been synthesized. The crystal structure of 2 revealed that the RuII atom lies on a distorted octahedral geometry with the deprotonated ligand (L2-) coordinated through β-ketoester group oxygen atoms. In vitro cytotoxic activity of the compounds was evaluated against 4T1 (murine mammary carcinoma) and B16-F10 (murine metastatic melanoma) tumor cells, and the non-tumor cell line BHK-21 (baby hamster kidney). Coordination with RuII resulted in expressive enhancement of cytotoxic activity. The precursors were inactive below 100 μM and the final RuII complexes (1-3) showed IC50 ranging from 2.0 to 12.8 μM; 2 being the most potent compound. DNA interaction studies revealed a greater capacity of the complexes to interact with DNA than the ligands, where, 2 exhibited the highest Kb constant of 2.2 × 104 M-1. Fluorescence investigation demonstrated that 1-3 are capable of quenching the fluorescence emission of the EtdBr-DNA complex up to 40%. Molecular docking showed that the interaction of 1-3 between the DNA base pairs from the coumarin portion was with scores of 67.28, 68.62 and 64.88, respectively, and 75.45 for ellipticine, suggesting an intercalative mode of binding. Our findings show that the RuII complexes are eligible for continuing to be investigated as potential antitumor compounds.

DNA groove-binding and acid-base properties of a Ru(II) complex containing anthryl moieties

DNA groove binders have been poorly studied as compared to the intercalators. A novel Ru(II) complex of [Ru(aeip)₂(Haip)](PF₆)₂ {Haip = 2-(9-anthryl)-1H-imidazo[4,5-f][1,10]phenanthroline and aeip = 2-(anthracen-9-yl)-1-ethyl-imidazo[4,5-f][1, 10]phenanthroline} is synthesized and characterized by elemental analysis, ¹H NMR spectroscopy and mass spectrometry. The complex is evidenced to be a calf-thymus DNA groove binder with a large intrinsic binding constant of 10⁶ M^-1 order of magnitude as supported by UV-visible absorption spectral titrations, salt effects, DNA competitive binding with ethidium bromide, DNA melting experiment, DNA viscosity measurements and density functional theory calculations. The acid-base properties of the complex studied by UV-Vis spectrophotometric titrations are reported as well.