ROS-mediated cell death induced by mixed ligand copper(II) complexes of l-proline and diimine: effect of co-ligand

Mixed-ligand copper(ii)-diimine complexes of 3-formylchromone-N 4-phenyl thiosemicarbazone: 5,6-dmp co-ligand confers enhanced cytotoxicity

The promising biological applications of thiosemicarbazone derivatives have inspired the design, synthesis, and study of their Cu(ii) complexes for anticancer therapeutic applications. Herein, we have evaluated the DNA/protein binding, DNA cleaving, and cytotoxic properties of four mixed-ligand Cu(ii) complexes of the type [Cu(L)(diimine)](NO3) 1-4, where HL is 4-oxo-4H-chromene-3-carbaldehyde-4(N)-phenylthiosemicarbazone and diimine is 2,2'-bipyridine (bpy, 1) 1,10-phenanthroline (phen, 2), 5,6-dimethyl-1,10-phenanthroline (5,6-dmp, 3), or dipyrido-[3,2-f:2',3'-h]-quinoxaline (dpq, 4). Interestingly, complex 3 with higher lipophilicity shows stronger DNA binding and oxidative DNA cleavage, higher ROS production, and more reversible redox behaviour, resulting in its remarkable cytotoxicity (IC50, 1.26 μM) against HeLa cervical cancer cells, and rendering it 5 times more potent than the widely used drug cisplatin. The same complex induces enhanced apoptotic cell death on HeLa cells but lower toxicity towards the non-cancerous PBMC cells. Molecular docking studies suggest that all the complexes bind in the minor groove of DNA and subdomain II of HSA, which is in close agreement with the experimental results. Also, 3 shows cytotoxicity higher than the analogous mixed ligand Cu(ii) complexes, reported already, emphasizing the importance of co-ligand in tuning the anticancer activity.

Crystal structure of [2-({[2-(dimethylamino-κN)ethyl]imino-κN}methyl)phenolato-κO](1,10-phen-anthroline-κ2 N,N')copper(II) perchlorate

The title compound, [Cu(C11H15N2O)(C12H8N2)]ClO4 or [Cu(L)(phen)](ClO4) {where L refers to the deprotonated form of 2-[(2-di-methyl-amino-ethyl-imino)-meth-yl]phenol} and phen is 1,10-phenanthroline) is a mononuclear mixed ligand copper(II) complex. The CuII atom is coordinated by two N and one O atoms of the tridentate Schiff base ligand (HL) and two N atoms of the 1,10-phenanthroline ligand, resulting in a five-coordinate complex. The asymmetric unit of the title complex contains two crystallographically independent complex cations (a and b) with a slightly different geometry around the CuII ion. The value of the trigonality index τ, indicates that in both cations a and b, the CuII atoms display a square-pyramidal distorted trigonal-bipyramidal (SPDTBP) geometry, although the distortion is greater for cation a.

Novel Ru(II)-bipyridine/phenanthroline-lapachol complexes as potential anti-cancer agents

For the first time, we herein report on the syntheses of two new Ru(II)/bipyridine/phenanthroline complexes containing lapachol as ligand: complex (1), [Ru (bipy)₂(Lap)]PF₆ and complex (2), [Ru(Lap)(phen)₂]PF₆, where bipy = 2,2'-bipyridine and ph en = 1,10-phenanthroline; Lap = lapachol (2-hydroxy-3-(3-methylbut-2-en-1- yl)naphthalene-1,4-dione). The complexes were synthesized and characterized by elemental analyses, molar conductivity, mass spectrometry, ultraviolet-visible and infrared spectroscopies, nuclear magnetic resonance (¹H, ¹³C), and single crystal X-ray diffraction, for complex (2). In addition, in vitro cytotoxicity was tested against six cancer cells: A549 (lung carcinoma); DU-145 (human prostate carcinoma); HepG2 (human hepatocellular carcinoma), PC-3 (human prostate adenocarcinoma); MDA-MB-231 (human breast adenocarcinoma); Caco-2 (human colorectal adenocarcinoma), and against two non-cancer cells, FGH (human gingival normal fibroblasts) and PNT-2 (prostate epithelial cells). Complex (1) was slightly more toxic and selective than complex (2) for all cell lines, except against the A549 cells, where (2) was more potent than complex (1). The complexes induced an increase in the reactive oxygen species, and the co-treatment with N-acetyl-L-cysteine remarkably suppressed the ROS generation and prevented the reduction of cell viability, suggesting that the cytotoxicity of the complexes is related to the ROS-mediated pathway. Further studies indicated that the complexes may bind to DNA via minor groove interaction. Our studies also revealed that free Lap induces gene mutations in Salmonella Typhimurium, nevertheless, the complexes demonstrated the absence of genotoxicity by the Ames test. The present study provides a relevant contribution to understanding the anti-cancer potential and genetic toxicological events of new ruthenium complexes containing the lapachol molecule as a ligand.

Copper(II) Phenanthroline-Based Complexes as Potential AntiCancer Drugs: A Walkthrough on the Mechanisms of Action

Copper is an endogenous metal ion that has been studied to prepare a new antitumoral agent with less side-effects. Copper is involved as a cofactor in several enzymes, in ROS production, in the promotion of tumor progression, metastasis, and angiogenesis, and has been found at high levels in serum and tissues of several types of human cancers. Under these circumstances, two strategies are commonly followed in the development of novel anticancer Copper-based drugs: the sequestration of free Copper ions and the synthesis of Copper complexes that trigger cell death. The latter strategy has been followed in the last 40 years and many reviews have covered the anticancer properties of a broad spectrum of Copper complexes, showing that the activity of these compounds is often multi factored. In this work, we would like to focus on the anticancer properties of mixed Cu(II) complexes bearing substituted or unsubstituted 1,10-phenanthroline based ligands and different classes of inorganic and organic auxiliary ligands. For each metal complex, information regarding the tested cell lines and the mechanistic studies will be reported and discussed. The exerted action mechanisms were presented according to the auxiliary ligand/s, the metallic centers, and the increasing complexity of the compound structures.

Synthesis, crystal structures, DNA interactions, and antitumor activity of two new dinuclear copper(ii) complexes with thiazole ligand

Two new dinuclear copper(ii) complexes, [Cu(ambt)2(cnba)4] (1) and [Cu(ambt)2(clba)4] (2) were synthesized with 2-amino-6-methoxybenzothiazole (ambt) as the main ligand. The structures of the two complexes were characterized by single-crystal XRD. The binding between CT-DNA (calf thymus DNA) and the complexes was evaluated by viscometry, electronic absorption, and fluorescence spectroscopy, and the binding constants were calculated using the Stern-Volmer equation. The complexes were intercalatively bound to CT-DNA, and [Cu(ambt)2(clba)4] having a greater binding constant than [Cu(ambt)2(cnba)4]. The two complexes had better antitumor properties against HepG2 (human hepatocellular carcinoma), A549 (human lung carcinoma), and HeLa (human cervical carcinoma) tumor cell lines than their respective ligands and cisplatin. Furthermore, [Cu(ambt)2(clba)4] had a stronger inhibitory ability on the three types of tumor cells than [Cu(ambt)2(cnba)4], which is congruent with the binding power of the complexes with DNA. Flow cytometry revealed that [Cu(ambt)2(cnba)4] and [Cu(ambt)2(clba)4] could trigger apoptosis or necrosis, arrest the HepG2 cell cycles, and cause G0/G1-phase cells to accumulate.