1,720,991 research outputs found
Ru(II) complexes with bioactive molecules: from 5-(N-heterocycles) to Ruthenacycles
No full textNovel metal Ru(II) complexes were selectively obtained, upon the reaction of [Ru(H)2(CO)(PPh3)3] with bioactive molecules as pyrrole carboxylate ligand, with the purpose to investigate the potential positive alterations added by metal coordination to promote enhanced bioactivity as prodrugs or a diagnostic metallo-tracers . Pyrrole 2−carboxilic acid (A), 2−pyrrolyl imino-phenol (B), 5−hydroxy−L−triptophan (5−HTP) (C) and Lasparagine (D) have been selected to form stable chelate organometallic systems, based on homoleptic O,O− or heteroleptic N,O−bonding fashion mode. Experiments were run by varying the reaction conditions (stoichiometry, temperature, solvent, time duration, and energy source) to selectively drive the reactions towards a single desired isomer. Stereo−electronic features and rotameric behaviour have been studied by spectroscopic techniques (ESI−MS, IR, heteronuclear NMR and VT NMR) and DFT (Density Functional Theory) calculations. The complexes obtained by double coordination through adding two equivalents of pyrrolyl carboxylate form bismonohapto (k1 -O) species, which have been further investigated in MeCN or EtOH/H2O mixture. Longer reaction times are required to afford the mixed species exhibiting simultaneous monohapto−, dihapto [k1 (O), k2 (O,O)−] coordination. Much drastic conditions are required for obtaining conjugated trans−bis-chelate species, which has been calculated to possess a relative higher energy. The B, C and D molecules, exhibiting a preferential N,Ocoordination mode, are reported in the following scheme, likely resulting in stabilized five−membered metallacycle species
Synthesis, characterization and biological studies of heterobimetallic Ru(II)-Au(I) complexes involving N-heterocyclic bidentate ligands.
No full textHeterobimetallic complexes are designed to exploit the chemistry and the beneficial effects shown by different metal species.Based on the combined anticancer properties of numerous ruthenium and gold compounds, the heterobimetallic ruthenium(II)-gold(I) complexes were obtained with the aim of investigating whether multifunctional heterometallic compounds could be promising candidates for cancer treatment.
The new complexes were synthesized starting from ruthenium(II) precursors bearing bidentate nitrogen donor heterocyclic ligands, specifically [Ru(bpy)2Cl2] (1) and [Ru(phen)2Cl2] (2) (bpy = 2,2’bipyridine or phen = 1,10-phenanthroline). Both ruthenium(II) and gold(I) organometallic fragments were incorporated through linkers trifunctional diphosphane methanide ligands.
The resulting complexes have been studied by analytical and spectroscopic techniques (ESI-ms, IR and heteronuclear bidimensional NMR). The cytotoxic activity of these complexes in cancer cells have been studied and in addition, as they have luminescent properties, biodistribution studies in order to know the possible biological target have been performed
Novel metallacyclic systems of Ru(II) as potential anticancer derivatives: Chemistry and Bioactivity.
No full textMany Ru(II) complexes are considered valid candidates as anticancer drugs since they show reduced cytotoxicity and genotoxicity in non-tumor cells. In addition, these compounds present lower chances of cancer cells developing intrinsic or acquired resistance due to their peculiar paths of action. Many cytotoxic metal complexes of Ru(II) with NSAIDs (as ibuprofen, naproxen or acetylsalicylic acid) have been reported as effective antitumor agents.Furthermore, we are convinced that the incorporation of a gold atom into the Ru(II) metal skeleton may induce cooperative features, potentially enhancing anticancer properties.
Complexation studies of [Ru(H)2(CO)(PPh3)3] (1) with several ligands such as amino acid derivates as 5-hydroxy-L-triptophane or NSAIDs as ibuprofen or thiosalicylic acid (TSA), and its corresponding gold(I) complex [Au(TSA)(PPh3)], have been carried out with the aim to investigate the antitumor properties in addition to the potential increased bioactivity added by gold coordination. The ligands bearing oxygen or nitrogen donor heteroatoms are coordinated to the Ru(II) center through O,O- or N,O- bidentate fashion modes.
The resulting complexes have been studied by analytical and spectroscopic techniques (ESI-MS, IR and heteronuclear bidimensional NMR) and their cytotoxic activities have been evaluated towards cancer cells
Catalytic hydroformylation of (1S,5S)-(???)- and (1R,5R)-(+)-??-pinene: stereoselective synthesis and spectroscopic characterization of (1S,2R,5S)-, (1S,2S,5S)-, (1R,2R,5R)- and (1R,2S,5R)-10-formylpinane
No full textCatalytic hydroformylation of (1S,5S)-(???)- and (1R,5R)-(+)-??-pinene: stereoselective synthesis and spectroscopic characterization of (1S,2R,5S)-, (1S,2S,5S)-, (1R,2R,5R)- and (1R,2S,5R)-10-formylpinan
Ruthenium-Thymine Acetate binding modes
No full textNucleobases coordinated to Ruthenium centres have shown several promising properties for cancer treatments, demonstrating to have efficiency comparable to that of cis-Pt compounds, limiting toxic effects to intact cells and overcoming the drugs resistance after longer treatments. Thymine acetate (THAc) is proposed as a biomimetic model ligand to design potential Ruthenium-based antitumor drugs. Herein we report the reaction between Ru(H)2(CO)(PPh3)3, 1 and THAcH. The X-ray structure of the mono-,dihapto-thymine acetate species [(k1-O)(k2-O,O)Ru(THAc)2(CO)(PPh3)2] 2, unexpectedly exhibits cis-location for acetate ligands, likely ascribed to the prevalence of H-bonds and -stacking interactions. Conversely, DFT-calculations and NMR spectra suggest lower energy for the trans form where there are no contacts between the bulky phosphines. The DFT-calculated energies suggest the nature for NMR-intercepted plausible k1- or k2-intermediates. The carboxy-metal coordination is able to stabilize enol-tautomers through supramolecular H-interactions. The rotations of k1- and k2-acetate side arm of the THAc have also been exploited by correlating NMR signal patterns with the DFT energies.
Figure 1: Torsional barrier of k1-(O) 3 and k2-(O,O)
Suberoylanilide Hydroxamic Acid Analogs with Heteroaryl Amide Group and Different Chain Length: Synthesis and Effect on Histone Deacetylase
No full textThis review covers the last 25 years of the literature on analogs of suberoylanilide hydroxamic acid (SAHA, known also as vorinostat) acting as an HDAC inhibitor. In particular, the topic has been focused on the synthesis and biological activity of compounds where the phenyl group (the surface recognition moiety, CAP) of SAHA has been replaced by an azaheterocycle through a direct bond with amide nitrogen atom, and the methylene chain in the linker region is of variable length. Most of the compounds displayed good to excellent inhibitory activity against HDACs and in many cases showed antiproliferative activity against human cancer cell lines
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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