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- Novel ruthenium methylcyclopentadienyl complex bearing a bipyridine perfluorinated ligand shows strong activity towards colorectal cancer cellsPublication . Teixeira, Ricardo G.; Brás, Ana Rita; Côrte-Real, Leonor; Tatikonda, Rajendhraprasad; Sanches, Anabela; Robalo, Maria Paula; Avecilla, Fernando; Moreira, Tiago; Garcia, M. Helena; Haukka, Matti; Preto, Ana; Valente, AndreiaThree new compounds have been synthesized and completely characterized by analytical and spectroscopic techniques. The new bipyridine-perfluorinated ligand L1 and the new organometallic complex [Ru(eta(5)-MeCp)(PPh3)(2)Cl] (Ru1) crystalize in the centrosymmetric triclinic space group P (1) over bar. Analysis of the phenotypic effects induced by both organometallic complexes Ru1 and [Ru(eta(5)-MeCp)(PPh3)(L1)] [CF3SO3] (Ru2), on human colorectal cancer cells (SW480 and RKO) survival, showed that Ru2 has a potent anti-proliferative activity, 4-6 times higher than cisplatin, and induce apoptosis in these cells. Data obtained in a noncancerous cell line derived from normal colon epithelial cells (NCM460) revealed an intrinsic selectivity of Ru2 for malignant cells at low concentrations, showing the high potential of this compound as a selective anticancer agent. (C) 2017 Elsevier Masson SAS. All rights reserved.
- η6-(2-phenoxyethanol) ruthenium(II)-complexes of 2,2′-bipyridine and its derivatives: Solution speciation and kinetic behaviourPublication . Nogueira, Guilherme; Domotor, Orsolya; Pilon, Adhan; Robalo, Maria Paula; Avecilla, Fernando; Garcia, M. Helena; Enyedy, Eva Anna; Valente, AndreiaA novel family of Ru-II-arene compounds with the general formula of [Ru-II(eta(6)-(2-phenoxyethanol))(L) Cl](+) (L: 2,2'-bipyridine (bpy) (3), 4,4'-dimethyl-2,2'-bipyridine (4) and 4,4'-diyldimethanol-2,2'-bipyridine (5)) was synthesized and characterized by standard spectroscopic and analytical methods. Complex 3 was further studied by single-crystal X-ray diffraction analysis, showing a pseudo octahedral geometry and strong pi-pi lateral stacking interactions in the crystal packing. Effect of the substituents on the electrochemical properties and on the aqueous solution stability was monitored by cyclic voltammetry, UV-Vis and H-1 NMR spectroscopy. Complexes 3-5 presented multiple irreversible redox processes according to their cyclic voltammograms recorded in acetonitrile, and their Ru-II/Ru-III oxidation peaks were found at ca. +1.6 V. Hydrolysis of the binuclear [Ru-II(eta(6)-(2-phenoxyethanol))(mu(2)-Cl)Cl](2) precursor (1) resulted in binuclear hydroxido bridged species [(Ru-II(eta(6)-(2-phenoxyethanol)))(2)(mu-OH)(3)](+) and [(Ru-II(eta(6)-(2-phenoxyethanol)))(2)(mu-OH)(2)Z(2)] (Z = H2O/Cl-) in the presence of chloride ions in water. The hydrolytic behaviour of this Ru-II precursor is similar to that of the analogous species [Ru-II(eta(6)-p-cymene)(mu(2)-Cl)Cl](2) regarding the hydrolysis products and their stability constants. Formation of complexes 3 -5 by reaction of the Ru-II precursor with the (N, N) bidentate ligands was found to be relatively slow in aqueous solution. The complexation is complete already at pH 1 due to the formation of [Ru-II(eta(6)-(2-phenoxyethanol))(L)Z] complexes of significantly high stability in all cases, which are predominant species up to pH 6. However, besides the formation of the mixed hydroxido species [Ru-II(eta(6)-(2-phenoxyethanol))(L)(OH)] + at neutral and basic pH values, the slow oxidation of the RuII centre takes place as well leading to the partial loss of the arene moiety. The rate of these processes depends on the pH and its maximum was found at pH 8-9. Additionally the chlorido/aqua co-ligand exchange processes of the [Ru-II(eta(6)-(2-phenoxyethanol))(L)Cl](+) species were also monitored and only similar to 5% of the chlorido ligand was found to be replaced by water in 0.1 M chloride ion containing aqueous solutions at pH 5.
- The key role of coligands in novel ruthenium(II)-cyclopentadienyl bipyridine derivatives: ranging from non-cytotoxic to highly cytotoxic compoundsPublication . Côrte-Real, Leonor; Robalo, Maria Paula; Marques, Fernanda; Nogueira, Guilherme; Avecilla, Fernando; Silva, Tiago J. L.; Santos, Filipa C.; Tomaz, A. Isabel; Garcia, M. Helena; Valente, AndreiaA new family of eight ruthenium(II)-cyclopentadienyl bipyridine derivatives, bearing nitrogen, sulfur, phosphorous and carbonyl sigma bonded coligands, has been synthesized. Compounds bearing nitrogen bonded coligands were found to be unstable in aqueous solution, while the others presented appropriate stabilities for the biologic assays and pursued for determination of IC50 values in ovarian (A2780) and breast (MCF7 and MDAMB231) human cancer cell lines. These studies were also carried out for the [5: HSA] and [6: HSA] adducts (HSA=human serum albumin) and a better performance was found for the first case. Spectroscopic, electrochemical studies by cyclic voltammetry and density functional theory calculations allowed us to get some understanding on the electronic flow directions within the molecules and to find a possible clue concerning the structural features of coligands that can activate bipyridyl ligands toward an increased cytotoxic effect. X-ray structure analysis of compound [Ru(η(5)-C5H5)(bipy)(PPh3)][PF6] (7; bipy=bipyridine) showed crystallization on C2/c space group with two enantiomers of the [Ru(η(5)-C5H5)(bipy)(PPh3)](+) cation complex in the racemic crystal packing.
- Methyl-cyclopentadienyl ruthenium compounds with 2,2 '-bipyridine derivatives display strong anticancer activity and multidrug resistance potentialPublication . 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, AndreiaNew 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.
- The key role of coligands in novel ruthenium(II)-cyclopentadienyl bipyridine derivatives: Ranging from non-cytotoxic to highly cytotoxic compoundsPublication . Côrte-Real, Leonor; Robalo, Maria Paula; Marques, Fernanda; Nogueira, Guilherme; Avecilla, Fernando; Silva, Tiago J.L.; Santos, Filipa C.; Tomaz, A. Isabel; Garcia, M. Helena; Valente, AndreiaA new family of eight ruthenium(II)-cyclopentadienyl bipyridine derivatives, bearing nitrogen, sulfur, phosphorous and carbonyl sigma bonded coligands, has been synthesized. Compounds bearing nitrogen bonded coligands were found to be unstable in aqueous solution, while the others presented appropriate stabilities for the biologic assays and pursued for determination of IC50 values in ovarian (A2780) and breast (MCF7 and MDAMB231) human cancer cell lines. These studies were also carried out for the [5: HSA] and [6: HSA] adducts (HSA = human serum albumin) and a better performance was found for the first case. Spectroscopic, electrochemical studies by cyclic voltammetry and density functional theory calculations allowed us to get some understanding on the electronic flow directions within the molecules and to find a possible clue concerning the structural features of coligands that can activate bipyridyl ligands toward an increased cytotoxic effect. X-ray structure analysis of compound [Ru(eta(5)-C5H5)(bipy)(PPh3)][PF6] (7; bipy = bipyridine) showed crystallization on C2/c space group with two enantiomers of the [Ru(eta(5)-C5H5)(bipy)(PPh3)](+) cation complex in the racemic crystal packing. (C) 2015 Elsevier Inc All rights reserved.
- Synthesis of organometallic Ruthenium(II) complexes with strong activity against several human canceer cell linesPublication . Morais, Tânia S.; Silva, Tiago J. L.; Marques, Fernanda; Robalo, Maria Paula; Avecilla, Fernando; Madeira, Paulo J. Amorim; Mendes, Paulo J. G.; Santos, Isabel; Garcia, M. HelenaA new family of "RuCp" (Cp=eta(5)-C5H5) derivatives with bidentate N,O and N,N'-heteroaromatic ligands revealed outstanding cytotoxic properties against several human cell lines namely, A2780, A2780CisR, HT29, MCF7, MDAMB231, and PD. IC50 values were much lower than those found for cisplatin. Crystal structure of compound 4 was determined by X-ray diffraction studies. Density functional theory (DFT) calculations performed for compound 1 showed electronic flow from the ruthenium center to the coordinated bidentate ligand, in agreement with the electrochemical studies and the existence of a metal-to-ligand charge-transfer (MLCT) band evidenced by spectroscopic data.