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The solid solutions (Per)(2)[PtxAu(1-x)(mnt)(2)]; alloying para-and diamagnetic anions in two-chain compounds

Publication . Matos, Manuel; Bonfait, Gregoire; Santos, Isabel C.; Afonso, Monica L.; Henriques, Rui T.; Almeida, Manuel

The alpha-(Per)(2)[M(mnt)(2)] compounds with M = Pt and Au are isostructural two-chain solids that in addition to partially oxidized conducting perylene chains also contain anionic chains that can be either paramagnetic in the case of M = Pt or diamagnetic for M = Au. The electrical transport and magnetic properties of the solid solutions (Per)(2)[Pt-x-Au(1-x)(mnt)(2)] were investigated. The incorporation of paramagnetic [Pt(mnt)(2)] impurities in the diamagnetic chains, and the effect of breaking the paramagnetic chains with diamagnetic centers for the low and high Pt range of concentrations were respectively probed. In the low Pt concentration range, there is a fast decrease of the metal-to-insulator transition from 12.4 K in the pure Au compound to 9.7 K for x = 0.1 comparable to the 8.1 K in the pure Pt compound. In the range x = 0.5-0.95, only beta-phase crystals could be obtained. The spin-Peierls transition of the pure Pt compound, simultaneous with metal-to-insulator (Peierls) transition is still present for 2% of diamagnetic impurities (x = 0.98) with transition temperature barely affected. Single crystal X-ray diffraction data obtained a high-quality structural refinement of the alpha- phase of the Au and Pt compounds. The beta-phase structure was found to be composed of ordered layers with segregated donors and anion stacks, which alternate with disordered layers. The semiconducting properties of the beta-phase are due to the disorder localization effects.

2017-06Journal article

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Methyl-cyclopentadienyl ruthenium compounds with 2,2 '-bipyridine derivatives display strong anticancer activity and multidrug resistance potential

Publication . Côrte-Real, Leonor; Gonçalves Teixeira, Ricardo; Girio, Patrícia; Comsa, Elisabeta; MORENO, Alexis; Nasr, Rachad; Baubichon-Cortay, Helene; Avecilla, Fernando; Marques, Fernanda; Robalo, Maria Paula; Mendes, Paulo; Prates Ramalho, João P.; Garcia; Falson, Pierre; Valente, Andreia

New ruthenium methyl-cyclopentadienyl compounds bearing bipyridine derivatives with the general formula [Ru(eta(5)-MeCp)(PPh3)(4,4'-R-2,2'-bpy)](+) (Ru1, R = H; Ru2, R = CH3; and Ru3, R = CH2OH) have been synthesized and characterized by spectroscopic and analytical techniques. Ru1 crystallized in the monoclinic P2(1)/c, Ru2 in the triclinic P (1) over bar, and Ru3 in the monoclinic P2(1)/n space group. In all molecular structures, the ruthenium center adopts a "piano stool" distribution. Density functional theory calculations were performed for all complexes, and the results support spectroscopic data. Ru1 and Ru3 were poor substrates of the main multidrug resistance human pumps, ABCB1, ABCG2, ABCC1, and ABCC2, while Ru2 displayed inhibitory properties of ABCC1 and ABCC2 pumps. Importantly, all compounds displayed a very high cytotoxic profile for ovarian cancer cells (sensitive and resistant) that was much more pronounced than that observed with cisplatin, making them very promising anticancer agents.

2018-04-16Journal article

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Ruthenium carboranyl complexes with 2,2 '-bipyridine derivatives for potential bimodal therapy application

Publication . Gonçalves Teixeira, Ricardo; Marques, Fernanda; Robalo, M. Paula; Fontrodona, Xavier; Garcia, M. Helena; Geninatti Crich, Simonetta; Vinas, Clara; Valente, Andreia

Ruthenium complexes of carboranyl ligands offer the possibility of dual action (chemo + radiotherapy) that might result in significant clinical benefits. In that frame, we describe herein the development of ruthenium-carboranyl complexes bearing bipyridyl derivatives with the general formula [3-CO-3,3-{kappa(2)-4,4 '-R-2-2,2 '-bipy}-closo-3,1,2-RuC2B9H11] (R = CH3,RuCB1or R = CH2OH,RuCB2). Both compounds crystallized in the monoclinic system, showing the expected three-legged piano stool structure. The ruthenacarboranes are stable in cell culture media and were tested against two cell lines that have shown favorable clinical responses with BNCT, namely melanoma (A375) and glioblastoma (U87).RuCB1shows no cytotoxic activity up to 100 mu M whileRuCB2showed moderate activity for both cell lines. Cell distribution assays showed thatRuCB2presents high boron internalization that is proportional to the concentration used indicating thatRuCB2presents features to be further studied as a potential anticancer bimodal agent (chemo + radiotherapy).

2020-04-28Journal article

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Half-sandwich Ru(p-cymene) compounds with diphosphanes: In Vitro and In Vivo evaluation as potential anticancer metallodrugs

Publication . Lenis Rojas, Oscar; Robalo, M. Paula; Tomaz, Ana Isabel; Fernandes, Alexandra; Roma-Rodrigues, Catarina; Gonçalves Teixeira, Ricardo; Marques, Fernanda; FOLGUEIRA, MONICA; Yáñez, Julián; Alba-González, Anabel; Salamini-Montemurri, Martin; Pech-Puch, Dawrin; Vázquez-García, Digna; López-Torres, Margarita; Fernandez, Alberto; Fernandez, Jesus J.

Ruthenium(II) complexes are currently considered attractive alternatives to the widely used platinum-based drugs. We present herein the synthesis and characterization of half-sandwich ruthenium compounds formulated as [Ru(p-cymene)(L)Cl]-[CF3SO3] (L = 1,1-bis(methylenediphenylphosphano)ethylene, 1; L = 1,1-bis(diphenylphosphano)ethylene, 2), which were characterized by elemental analysis, mass spectrometry, H-1 and P-31{H-1} NMR, UV-vis and IR spectroscopy, conductivity measurements and cyclic voltammetry. The molecular structures for both complexes were determined by single-crystal X-ray diffraction. Their cytotoxic activity was evaluated using the MTT assay against human tumor cells, namely ovarian (A2780) and breast (MCF7 and MDA-MB-231). Both complexes were active against breast adenocarcinoma cells, with complex 1 exhibiting a quite remarkable cytotoxicity in the submicromolar range. Interestingly, at concentrations equivalent to the IC50 values in the MCF7 cancer cells, complexes 1 and 2 presented lower cytotoxicity in normal human primary fibroblasts. The antiproliferative effects of 1 and 2 in MCF7 cells might be associated with the induction of reactive oxygen species (ROS), leading to a combined cell death mechanism via apoptosis and autophagy. Despite the fact that in vitro a partial intercalation between complexes and DNA was observed, no MCF7 cell cycle delay or arrest was observed, indicating that DNA might not be a direct target. Complexes 1 and 2 both exhibited a moderate to strong interaction with human serum albumin, suggesting that protein targets may be involved in their mode of action. Their acute toxicity was evaluated in the zebrafish model. Complex 1 (the most toxic of the two) exhibited a lethal toxicity LC50 value about 1 order of magnitude higher than any IC50 concentrations found for the cancer cell models used, highlighting its therapeutic relevance as a drug candidate in cancer chemotherapy.

2021-02-11Journal article

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Ru-II(p‑cymene) compounds as effective and selective anticancer candidates with no toxicity in vivo

Publication . Lenis-Rojas, Oscar A.; Robalo, Maria Paula; Tomaz, Ana Isabel; Carvalho, Andreia; Fernandes, Alexandra; Marques, Fernanda; FOLGUEIRA, MONICA; Yáñez, Julián; Vázquez-García, Digna; López-Torres, Margarita; Fernandez, Alberto; Fernandez, Jesus J.

Ruthenium(II) complexes are currently considered a viable alternative to the widely used platinum complexes as efficient anticancer agents. We herein present the synthesis and characterization of half-sandwich ruthenium compounds with the general formula [Ru(p-cymene)(L-N,N)Cl][CF3SO3] (L = 3,6-di-2-pyridyl-1,2,4,5-tetrazine (1) 6,7-dimethyl-2,3-bis(pyridin-2-yl)quinoxaline (2)), which have been synthesized by substitution reactions from the precursor dimer [Ru(p-cymene)(Cl)(μ-Cl)]2 and were characterized by elemental analysis, mass spectrometry, 1H NMR, UV–vis, and IR spectroscopy, conductivity measurements, and cyclic voltammetry. The molecular structure for complex 2 was determined by single-crystal X-ray diffraction. The cytotoxic activity of these compounds was evaluated against human tumor cells, namely ovarian carcinoma A2780 and breast MCF7 and MDAMB231 adenocarcinoma cells, and against normal primary fibroblasts. Whereas the cytotoxic activity of 1 is moderate, IC50 values found for 2 are among the lowest previously reported for Ru(p-cymene) complexes. Both compounds present no cytotoxic effect in normal human primary fibroblasts when they are used at the IC50 concentration in A2780 and MCF7 cancer cells. Their antiproliferative capacity is associated with a combined mechanism of apoptosis and autophagy. A strong interaction with DNA was observed for both with a binding constant value of the same magnitude as that of the classical intercalator [Ru(phen)2(dppz)]2+. Both complexes bind to human serum albumin with moderate to strong affinity, with conditional binding constants (log Kb) of 4.88 for complex 2 and 5.18 for complex 1 in 2% DMSO/10 mM Hepes pH7.0 medium. The acute toxicity was evaluated in zebrafish embryo model using the fish embryo acute toxicity test (FET). Remarkably, our results show that compounds 1 and 2 are not toxic/lethal even at extremely high concentrations. The novel compounds reported herein are highly relevant antitumor metallodrug candidates, given their in vitro cytotoxicity toward cancer cells and the lack of in vivo toxicity.

2018-11-05Journal article

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