2-(3,5-Dibromo-4-hydroxyphenyl)imidazo[4,5-f][1,10]phenanthrolinoruthenium(II) complexes: synthesis, characterization, cytotoxicity, apoptosis, DNA-binding and antioxidant activity

Abstract

A new ligand DBHIP and its two ruthenium(II) complexes [Ru(dmb)(2)(DBHIP)](ClO(4))(2) (1) and [Ru(dmp)(2)(DBHIP)](ClO(4))(2) (2) have been synthesized and characterized. The cytotoxicity of DBHIP and complexes 1 and 2 has been assessed by MTT assay. The apoptosis studies were carried out with acridine orange/ethidium bromide (AO/EB) staining methods. The binding behaviors of these complexes to calf thymus DNA (CT-DNA) were studied by absorption titration, viscosity measurements, thermal denaturation and photoactivated cleavage. The DNA-binding constants of complexes 1 and 2 were determined to be 8.64 +/- 0.16 x 10(4) (s = 1.34) and 2.79 +/- 0.21 x 10(4) (s = 2.17) M(-1). The results suggest that these complexes interact with DNA through intercalative mode. The studies on the mechanism of photocleavage demonstrate that superoxide anion radical (O(2)(*-)) and singlet oxygen ((1)O(2)) may play an important role in the DNA cleavage. The experiments on antioxidant activity show that these compounds also exhibit good antioxidant activity against hydroxyl radical (OH*).

Two new mixed copper(ii)–dipeptide complexes of N,N-donor heterocycle ligands: studies on their non-covalent DNA binding, chemical nuclease, antioxidant and anticancer activities

“…The superoxide anion radical (O 2 À c) is one of the most reactive species of ROS, which can result in cell membrane and DNA damage, aging, chromosomal aberrations, carcinogenesis and further initiate or propagate the development of many diseases. 65,66 Therefore, it's important for further investigation of the O 2 À c scavenging activities of the metal complexes. As shown in Fig.…”

Mechanism and Efficiency of Cell Death of Type II Photosensitizers: Effect of Zinc Chelation†

“…4). Although we can observe some features of each of the known cell‐death processes (36,37), the most important difference is the high level of staining with EB (red cells) in cells treated with P3, both 24 and 48 h after PDT. This is another piece of evidence pointing to the concept that free‐base porphyrins, which accumulate in mitochondria induce a higher level of necrosis compared with zinc‐chelated porphyrins, which do not accumulate in mitochondria.…”

“…Fluorescence microscopy: acridine orange and ethidium bromide double staining. After 24 and 45 h, PDT cells were stained with 1:1 acridine orange and ethidium bromide (AO/EB) 1 μg·mL −1 for 10 min following the protocol previously described (36,37). Images were acquired in a fluorescence microscope Axiovert 200 (Zeiss, Germany), 130× magnification and photographed on a Canon Power Shot G10.…”

“…Images were acquired in a fluorescence microscope Axiovert 200 (Zeiss, Germany), 130× magnification and photographed on a Canon Power Shot G10. Living cells were observed as green, necrotic cells as red, early apoptotic cells as green with nucleus exhibiting strong emission because of the chromatin condensation and autophagic cells were seen as green with orange vacuoles (36,37).…”

Synthesis, cellular uptake, apopotosis, cytotoxicity, cell cycle arrest, interaction with DNA and antioxidant activity of ruthenium(II) complexes

“…When complexes 1 and 2 are treated with CT DNA (0.25 mM) and the concentrations of ruthenium complexes are increased from a ratio of R ¼ 0e0. 16 …”