The antitumor effect and toxicity of a ruthenium(II) complex in vivo

The Antitumor and Toxicity Effects of Ruthenium(II) Complexes on Heterotopic Murine Colon Carcinoma Model

The aim of the present study was to examine the antitumor and toxicity effects of ruthenium(II) complexes, [Ru(Cltpy)(en)Cl][Cl] (Ru-1) and [Ru(Cl-tpy)(dach)Cl][Cl] (Ru-2) on heterotopic murine colon carcinoma model.

For tumor induction, 1×106 CT26 cells suspended in 100 μl of DMEM were injected subcutaneously into flank of male BALB/c mice. Treatment groups were as follows: Ru-1, Ru-2, oxaliplatin and control (saline). The intraperitoneal administration of the tested complexes began on 6th day after CT26 cells inoculation. Each complex was administered at dose of 5 mg/kg, twice weekly, four doses in total. To assess toxicity, serum values of urea, creatinine, AST and ALT were determined and histopathological analysis of organs and tumor were performed. In order to assess the effects of Ru(II) complexes on markers of oxidative stress and antioxidant defense system, we determined the TBARS, GSH, SOD and CAT in the homogenate of tumor, heart, liver, lungs and kidney tissues.

The findings indicate that Ru-1 and Ru-2 exerts equal or better antitumor activity in comparison with oxaliplatin, but with pronounced toxic effects such as reduced survival rate, cardiotoxicity, nephrotoxicity and hepatotoxicity. The increased index of lipid peroxidation in the tissues of the kidneys and heart, but decreased in tumor tissue, after Ru(II) complexes administration, indicates the importance of the induction of oxidative stress as a possible mechanism of nephrotoxicity and cardiotoxicity, but not the mechanism by which they realize antitumor activity.

Additional studies are needed to elucidate the mechanism of antitumor activity and toxicity of the Ru(II) complexes.

Spectrophotometric Determination of Formation Constants of Iron(III) Complexes with Several Ligands

Dye-sensitized solar cells transform solar light into electricity. One commonly used dye is a ruthenium complex. However, the use of ruthenium has been shown to have several disadvantages. In this study, via singular spectrum analysis using HypSpec software, we determined the formation constants and calculated individual electronic spectra of species of iron(III) with several ligands (1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 2,2′-bipyridyl, 5,5-dimethyl-2,2′-bipyridyl, 4,4′-di-tert-butyl-2,2′-bipyridyl, 1,10-phenanthroline, and 3,4,7,8-tetramethyl-1,10-phenanthroline) in methanol solution. We present a spectral comparison of the complexes reported here to the ruthenium complex: tris-(2,2′-bipyridyl)ruthenium(II).

Anti-Proliferative, Anti-Angiogenic and Safety Profiles of Novel HDAC Inhibitors for the Treatment of Metastatic Castration-Resistant Prostate Cancer

Metastatic castration-resistant prostate cancer (CRPC) has a five-year survival rate of 28%. As histone deacetylases (HDACs) are overexpressed in CRPC, the HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) was trialled in CRPC patients but found to be toxic and inefficacious. Previously, we showed that novel HDAC inhibitors (Jazz90 (N1-hydroxy-N⁸-(4-(pyridine-2-carbothioamido)phenyl)octanediamide) and Jazz167 ([chlorido(η⁵-pentamethylcyclopentadieny[1–4](N1-hydroxy-N⁸-(4-(pyridine-2-carbothioamido-κ²N,S)phenyl)octanediamide)rhodium(III)] chloride) had a higher cancer-to-normal-cell selectivity and superior anti-angiogenic effects in CRPC (PC3) cells than SAHA. Thus, this study aimed to further investigate the efficacy and toxicity of these compounds. HUVEC tube formation assays revealed that Jazz90 and Jazz167 significantly reduced meshes and segment lengths in the range of 55–88 and 43–64%, respectively. However, Jazz90 and Jazz167 did not affect the expression of epithelial-to-mesenchymal transitioning markers E-cadherin and vimentin. Jazz90 and Jazz167 significantly inhibited the growth of PC3 and DU145 spheroids and reduced PC3 spheroid branching. Jazz90 and Jazz167 (25, 50 and 75 mg/kg/day orally for 21 days) were non-toxic in male BALB/c mice. The efficacy and safety of these compounds demonstrate their potential for further in vivo studies in CRPC models.

Influence of the electron donor properties of hypericin on its sensitizing ability in DSSCs

Rising demands for renewable energy sources have led to the development of dye sensitized solar cells. It is a challenge to find a good and low cost sensitizer, which has a low environmental impact. In this work, we conducted spectroscopic and electrochemical experiments, as well as quantum-chemical calculations of the natural pigment hypericin, in order to provide insight into its sensitizing efficiency. To this end, three identical cells were made and characterized. Although this pigment exhibited good adsorption onto a semiconductor surface, a high molar absorption coefficient (43 700 L mol^-1 cm^-1) and favorable alignment of energy levels and provided a long lifetime of electrons (17.8 ms) in the TiO₂ photoanode, it was found that the efficiency of hypericin-sensitized solar cells was very low, only 0.0245%. We suggest that this inefficiency originated from a low injection of electrons into the conduction band of TiO_2. This conclusion is supported by the density functional theory calculations which revealed a low electron density in the anchoring groups of electronically excited hypericin. The results of this work could be valuable not only in the photovoltaic aspect, but also for application of hypericin in medicine in photodynamic therapy.

Ruthenium Complexes With Piplartine Cause Apoptosis Through MAPK Signaling by a p53-Dependent Pathway in Human Colon Carcinoma Cells and Inhibit Tumor Development in a Xenograft Model

Ruthenium complexes with piplartine, [Ru(piplartine)(dppf)(bipy)](PF₆)₂ (1) and [Ru(piplartine)(dppb)(bipy)](PF₆)₂ (2) (dppf = 1,1-bis(diphenylphosphino) ferrocene; dppb = 1,4-bis(diphenylphosphino)butane and bipy = 2,2′-bipyridine), were recently synthesized and displayed more potent cytotoxicity than piplartine in different cancer cells, regulated RNA transcripts of several apoptosis-related genes, and induced reactive oxygen species (ROS)-mediated apoptosis in human colon carcinoma HCT116 cells. The present work aimed to explore the underlying mechanisms through which these ruthenium complexes induce cell death in HCT116 cells in vitro, as well as their in vivo action in a xenograft model. Both complexes significantly increased the percentage of apoptotic HCT116 cells, and co-treatment with inhibitors of JNK/SAPK, p38 MAPK, and MEK, which inhibits the activation of ERK1/2, significantly reduced the apoptosis rate induced by these complexes. Moreover, significant increase in phospho-JNK2 (T183/Y185), phospho-p38α (T180/Y182), and phospho-ERK1 (T202/Y204) expressions were observed in cells treated with these complexes, indicating MAPK-mediated apoptosis. In addition, co-treatment with a p53 inhibitor (cyclic pifithrin-α) and the ruthenium complexes significantly reduced the apoptosis rate in HCT116 cells, and increased phospho-p53 (S15) and phospho-histone H2AX (S139) expressions, indicating induction of DNA damage and p53-dependent apoptosis. Both complexes also reduced HCT116 cell growth in a xenograft model. Tumor mass inhibition rates were 35.06, 29.71, and 32.03% for the complex 1 (15 μmol/kg/day), complex 2 (15 μmol/kg/day), and piplartine (60 μmol/kg/day), respectively. These data indicate these ruthenium complexes as new anti-colon cancer drugs candidates.

Acute toxic effects of ruthenium (II)/amino acid/diphosphine complexes on Swiss mice and zebrafish embryos

Anticancer potential of ruthenium complexes has been widely investigated, but safety evaluation studies are still scarce. Despite of ruthenium-based anticancer agents are known to cause fewer side effects compared to other metal-based drugs, these compounds are not fully free of toxicity, causing mainly nephrotoxicity. Based on the promising results from antitumor activity of the complexes [Ru(L-Met)(bipy)(dppb)]PF₆ (RuMet) and [Ru(L-Trp)(bipy)(dppb)]PF₆ (RuTrp), for the first time we investigated the toxicity profile of these complexes in rodent and zebrafish models. The acute oral toxicity was evaluated in Swiss mice. The mutagenic and genotoxic potential was determined by a combination of Micronucleus (MN) and Comet assay protocols, after exposure of Swiss mice to RuMet and RuTrp in therapeutic doses. Zebrafish embryos were exposed to these complexes, and their development observed up to 96 h post-fertilization. RuMet and RuTrp complexes showed low acute oral toxicity. Recorded behavioral changes were not recorded, nor were macroscopic morphological changes or structural modifications in the liver and kidneys. These complexes did not cause genetic toxicity, presenting a lack of micronuclei formation and low DNA damage induction in the cells from Swiss mice. In contradiction, cisplatin treatment exhibited high mutagenicity and genotoxicity. RuMet and RuTrp showed low toxicity in the embryo development of zebrafish. The RuMet and RuTrp complexes demonstrated low toxicity in the two study models, an interesting property in preclinical studies for novel anticancer agents.