Effect of the extra-nuclear cation on the cytotoxicity and mechanism of action of pyridine-2,6-dicarboxylate Ga(III) complexes.

Two Ga(III) complexes (C1) and (C2) were prepared by the one-pot reaction of pyridine-2,6-dicarboxylic acid and aminopyridine derivatives with gallium(III) nitrate octahydrate. The compounds were characterized by single-crystal X-ray diffraction. The distorted octahedral geometry was confirmed by crystallographic data for both complexes. The study of the in vitro cytotoxicity of the compounds showed that the presence of different extra-nuclear cations can affect the cytotoxicity of the same anionic complexes. The most significant antiproliferative activity was observed for C1 (IC50 = 0.69 µM, MAE = 73.96%) and C2 (IC50 = 3.78 µM, MAE = 60.35%) (where MAE represents the maximal antiproliferative effect) against A431 cell line. The mechanistic study evidenced the same pathway for the death of A431 cells treated with the complexes, although the results for C2 were obtained at approximately five times the concentration of C1. According to the study, both complexes induced cell cycle arrest in G2/M phase in A431 cells by upregulating the levels of p21, p27, p-cdc25C, and p-cdc2 and downregulating the levels of cdc25C, cdc2, and cyclin B1. In addition, apoptosis via a caspase-dependent mitochondrial pathway was confirmed by a decrease in Bcl-2 family proteins and an increase in the expression of procaspase-9 and 3. Also, the complexes induced autophagic cell death by activating the RAGE /PI3KC3/Beclin 1 pathway in A431 cells. DATA AVAILABILITY: CCDC 874052 and 874055 contain the supplementary crystallographic data for C1 and C2, respectively. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/services/structures?pid=ccdc:874052,874055&sid=CCDCManual, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.

Template-Free Synthesis of Two New Luminescent One-Dimensional High-Nuclearity Silver Polyclusters.

The metallophilic properties, spherical configuration, and flexible coordination of silver ions make them prone to create various coordination modes and structural features. Therefore, with the increase of the complexities of self-assembly, the effect of various synthetic conditions in the final structure of silver compounds becomes diverse and attractive. In this study, two new silver polyclusters, 16- and 21-nuclearity, protected by multiple ligands including alkynyl, trifluoroacetate, and diphenylphosphinate, were synthesized and characterized by single-crystal X-ray diffraction, powder X-ray diffraction, and Fourier transform infrared (FTIR) spectroscopy. The optical properties and thermal stability of the polyclusters were studied by solid-state ultraviolet-visible (UV-vis) absorption and solid UV-vis diffuse reflectance spectra and gravimetric analysis, respectively. The formation of the two polyclusters can be fine-controlled by simply adjusting the stoichiometric ratio of diphenylphosphinate ligands to silver precursors under the same synthetic condition, leading to the different coordination modes between ligands and Ag centers. This work shows a facile and template-free method to synthesize and control the silver polycluster assembly, encouraging further development of new polyclusters with the potential for various applications.

Cytotoxicity and mechanism of action of metal complexes: An overview.

After the discovery of cisplatin, many metal compounds were investigated for the therapy of diseases, especially cancer. The high therapeutic potential of metal-based compounds is related to the special properties of these compounds, such as their redox activity and ability to target vital biological sites. The overproduction of ROS and the consequent destruction of the membrane potential of mitochondria and/or the DNA helix is one of the known pathways leading to the induction of apoptosis by metal complexes. The apoptosis process can occur via the death receptor pathway and/or the mitochondrial pathway. The expression of Bcl2 proteins and the caspase family play critical roles in these pathways. In addition to apoptosis, autophagy is another process that regulates the suppression or promotion of various cancers through a dual action. On the other hand, the ability to interact with DNA is an important property found in several metal complexes with potent antiproliferative effects against cancer cells. These interactions were classified into two important categories: covalent/coordinated or subtle, and non-coordinated interactions. The anticancer activity of metal complexes is sometimes achieved by the simultaneous combination of several mechanisms. In this review, the anticancer effect of metal complexes is mechanistically discussed by different pathways, and some effective agents on their antiproliferative properties are explained.

Evaluation of central-metal effect on anticancer activity and mechanism of action of isostructural Cu(II) and Ni(II) complexes containing pyridine-2,6-dicarboxylate.

Two Cu(II) (C1) and Ni(II) (C2) complexes were designed through the one-pot reaction of pyridine-2,6-dicarboxylic acid and 2-aminobenzimidazole respectively with copper(II) nitrate hexahydrate and nickel(II) nitrate hexahydrate. Both complexes were characterized by single-crystal X-ray diffraction and the distorted octahedral geometry was recognized for them. The MTT assay indicated that the complexes have a significant antiproliferative effect on BEL-7404 cells. IC50 values confirmed that C1 (IC50 = 0.56 µM) is several times more potent than C2 (IC50 = 5.13 µM). The similar cellular uptake of the complexes in mentioned cells led to this proposal that the production of ROS with different values can be the main reason for different cytotoxicity of the complexes. In this study, C1 and C2 caused BEL-7404 cells arrest at the G2/M and S phases, respectively. The expression of p53, Bax up-regulation, and Bcl-2 down-regulation and also activation of procaspase-9, and 3 indicated that apoptosis through a caspase-dependent mitochondrion pathway is a remarkable pathway in BEL-7404 cells treated by C1 while mechanistic studies proved that C2 induce death of BEL-7404 cells through the activation of RAGE/PI3KC3/Beclin 1 autophagic cell signaling pathway, more specifically. The cytostatic effect of the complexes in the BEL-7404 3D spheroid model was depicted.