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Roberto Santana Da Silva - One of the best experts on this subject based on the ideXlab platform.

  • Cytotoxicity, cellular uptake, and subcellular localization of a nitrogen oxide and aminopropyl-β-lactose derivative Ruthenium Complex used as nitric oxide delivery agent.
    Nitric oxide : biology and chemistry, 2019
    Co-Authors: J.s. Santos, Loyanne C.b. Ramos, Lucimara P. Ferreira, Vanessa Leira Campo, Lucas Cunha Dias De Rezende, Flavio Da Silva Emery, Roberto Santana Da Silva
    Abstract:

    Abstract This work investigates how the luminescent Ruthenium-nitrite Complexes cis-[Ru(py-bodipy)(dcbpy)2(NO2)](PF6) (I) and cis-[Ru(py-bodipy)(dcbpy-aminopropyl-β-lactose)2(NO2)](PF6) (II) behave toward the melanoma cancer cell line B16F10. The chemical structure and purity of the synthesized Complexes were analyzed by UV-Visible and FTIR spectroscopy, MALDI, HPLC, and 1H NMR. Spectrofluorescence helped to determine the fluorescence quantum yields and lifetimes of each of these Complexes. In vitro MTT cell viability assay on B16F10 cancer cells revealed that the Complexes possibly have a tumoricidal role. The metal-nitrite Complexes evidenced the dichotomous NO nature: at high concentration, NO exerted a tumoricidal effect, whereas cancer cells grew at low NO concentration. Flow cytometry or fluorescence microscopy aided cellular uptake calculation. Cell staining followed by fluorescence microscopy associated with organelle markers such as DAPI and Rhodamine 123 detected preferential intracellular localization of the Ruthenium-nitrite py-bodipy and aminopropyl lactose derivative Ruthenium Complex in mitochondria. Thus, the cytotoxicity of compounds (I) and (II) against B16F10 cancer cell line show concentration-dependent results. The present studies suggest that nitric oxide Ruthenium derivative compounds could be new potential chemotherapeutic agents against cytotoxic cells.

  • targeting the mitochondrial vdac in hepatocellular carcinoma using a polyclonal antibody conjugated to a nitrosyl Ruthenium Complex
    Journal of Biological Inorganic Chemistry, 2018
    Co-Authors: Loyanne Carla Barbosa Ramos, Roberto Santana Da Silva, Fernando P Rodrigues, Juliana C Biazzotto, Sergio Machado, Leonardo D Slep, Michael R Hamblin
    Abstract:

    The rational design of anti-cancer agents includes a new approach based on Ruthenium Complexes that can act as nitric oxide (NO) donor agents against specific cellular targets. One of the most studied classes of those compounds is based on bis(bipyridine) Ruthenium fragment and its derivative species. In this work, we present the chemical and cytotoxicity properties against the liver hepatocellular carcinoma cell line HepG2 of cis-[RuII(NO+)Cl(dcbpy)2]2- conjugated to a polyclonal antibody IgG (anti-VDAC) recognizing a cell surface marker. UV-visible bands of the Ruthenium Complex were assigned with the aid of density functional theory, which also allowed estimation of the structures that explain the biological effects of the Ruthenium Complex-IgG conjugate. The interaction of cis-[RuII(NO+)Cl(dcbpy)2]3- with mitochondria was evaluated due to the potential of these organelles as anti-cancer targets, and considering they interact with the anti-VDAC antibody. The cytotoxicity of cis-[RuII(NO+)Cl(dcbpy)2]3--anti-VDAC antibody was up to 80% greater in comparison to the free cis-[RuII(NO+)Cl(dcbpy)2]3- Complex. We suggest that this effect is due to site-specific interaction of the Complex followed by NO release.

  • a new nitrosyl Ruthenium Complex nitric oxide donor presents higher efficacy than sodium nitroprusside on relaxation of airway smooth muscle
    European Journal of Pharmaceutical Sciences, 2011
    Co-Authors: Patricia Ferreira Da Silva Castro, Roberto Santana Da Silva, Lusiane Maria Bendhack, Amanda C Pereira, Gerson J Rogrigues, Aline Carvalho Batista, Matheus Lavorenti Rocha
    Abstract:

    Abstract Nitric oxide (NO) has been demonstrated to be the primary agent in relaxing airways in humans and animals. We investigated the mechanisms involved in the relaxation induced by NO-donors, Ruthenium Complex [Ru(terpy)(bdq)NO + ] 3+ (TERPY) and sodium nitroprusside (SNP) in isolated trachea of rats contracted with carbachol in an isolated organs chamber. For instance, we verified the contribution of K + channels, the importance of sGC/cGMP pathway, the influence of the extra and intracellular Ca 2+ sources and the contribution of the epithelium on the relaxing response. Additionally, we have used confocal microscopy in order to analyze the action of the NO-donors on cytosolic Ca 2+ concentration. The results demonstrated that both compounds led to the relaxation of trachea in a dependent-concentration way. However, the maximum effect ( E max ) of TERPY is higher than the SNP. The relaxation induced by SNP (but not TERPY) was significantly reduced by pretreatment with ODQ (sGC inhibitor). Only TERPY-induced relaxation was reduced by tetraethylammonium (K + channels blocker) and by pre-contraction with 75 mM KCl (membrane depolarization). The response to both NO-donors was not altered by the presence of thapsigargin (sarcoplasmic reticulum Ca 2+ -ATPase inhibitor). The epithelium removal has reduced the relaxation only to SNP, and it has no effect on TERPY. The both NO-donors reduced the contraction evoked by Ca 2+ influx, while TERPY have shown a higher inhibitory effect on contraction. Moreover, the TERPY was more effective than SNP in reducing the cytosolic Ca 2+ concentration measured by confocal microscopy. In conclusion, these results show that TERPY induces airway smooth muscle relaxation by cGMP-independent mechanisms, it involves the fluxes of Ca 2+ and K + across the membrane, it is more effective in reducing cytosolic Ca 2+ concentration and inducing relaxation in the rat trachea than the standard drug, SNP.

  • development of nitrosyl Ruthenium Complex loaded lipid carriers for topical administration improvement in skin stability and in nitric oxide release by visible light irradiation
    Journal of Pharmaceutical and Biomedical Analysis, 2010
    Co-Authors: Franciane Marqueleoliveira, Roberto Santana Da Silva, Danielle Cristine De Almeida Santana, Stephânia Fleury Taveira, Deise Mirella Vermeulen, Anderson Rodrigo Moraes De Oliveira, Renata F V Lopez
    Abstract:

    Abstract The prominent nitric oxide (NO) donor [Ru(terpy)(bdqi)NO](PF6)3 has been synthesized and evaluated with respect to noteworthy biological effects due to its NO photorelease, including vascular relaxation and melanoma cell culture toxicity. The potential for delivering NO in therapeutic quantities is tenable since the nitrosyl Ruthenium Complex (NRC) must first reach the “target tissue” and then release the NO upon stimulus. In this context, NRC-loaded lipid carriers were developed and characterized to further explore its topical administration for applications such as skin cancer treatment. NRC-loaded solid lipid nanoparticles (SLN) and nanostructured lipid carriers were prepared via the microemulsification method, with average diameters of 275 ± 15 nm and 211 ± 31 nm and zeta potentials of −40.7 ± 10.4 mV and −50.0 ± 7.5 mV, respectively. In vitro kinetic studies of NRC release from nanoparticles showed sustained release of NRC from the lipid carriers and illustrated the influence of the release medium and the lyophilization process. Stability studies showed that NO is released from NRC as a function of temperature and time and due to skin contact. The encapsulation of NRC in SLN followed by its lyophilization, significantly improved the Complex stability. Furthermore, of particular interest was the fact that in the NO photorelease study, the NO release from the NRC-loaded SLN was approximately twice that of just NRC in solution. NRC-loaded SLN performs well enough at releasing and protecting NO degradation in vitro that it is a promising carrier for topical delivery of NO.

  • comparison of the mechanisms underlying the relaxation induced by two nitric oxide donors sodium nitroprusside and a new Ruthenium Complex
    Vascular Pharmacology, 2007
    Co-Authors: Daniella Bonaventura, Roberto Santana Da Silva, Renata De Lima, Juliana Aparecida Vercesi, Lusiane Maria Bendhack
    Abstract:

    Abstract We studied the mechanisms involved in the relaxation induced by nitric oxide (NO) donors, Ruthenium Complex ([Ru(terpy)(bdq)NO+]3+-TERPY) and sodium nitroprusside (SNP) in denuded rat aorta. Both NO donors induced vascular relaxation independent of the agonist used in the pre-contraction. [Ru(terpy)(bdq)NO+]3+ and SNP activated guanylyl cyclase (GC) and K+ channels. The production of cGMP induced by [Ru(terpy)(bdq)NO+]3+ — was higher than that obtained with SNP. The combination of GC inhibitor with K+channels blocker almost abolished the relaxation induced by the NO donors. The extracellular NO scavenger oxyhemoglobin reduced the potency without changing the maximum effect (Emax) of both NO donors. By using specific NO species scavengers, hydroxocobalamin and l -cysteine, we have identified the contribution of free radical NO (NO ) and nytroxil anion (NO−), respectively, to the rat aorta relaxation induced by both NO donors. The selective scavengers for NO and NO− reduced the potency but not the Emax of [Ru(terpy)(bdq)NO+]3+. However, the NO− scavenger had no effect on the relaxation induced by SNP and NO scavenger reduced only the potency to SNP. The inhibition of sarcoplasmic reticulum Ca2+-ATPase reduced only the potency of SNP without effect on the relaxation induced by [Ru(terpy)(bdq)NO+]3+. Our results demonstrate that both NO donors induce relaxation by activating the GC and K+ channels. The NO is the unique NO specie involved in the SNP-relaxation. On the other hand, the relaxant effect of [Ru(terpy)(bdq)NO+]3+ involves both NO and NO−, that produce higher concentration of cGMP. The inhibition of sarcoplasmic reticulum Ca2+-ATPase reduces the relaxation induced by SNP but it did not alter the relaxation induced by [Ru(terpy)(bdq)NO+]3+.

Khurram Saleem Joya - One of the best experts on this subject based on the ideXlab platform.

  • electrochemical in situ surface enhanced raman spectroscopic characterization of a trinuclear Ruthenium Complex ru red
    Journal of Raman Spectroscopy, 2013
    Co-Authors: Khurram Saleem Joya, Huub J M De Groot
    Abstract:

    To study the fate of a molecular di-μ-oxo-bridged trinuclear Ruthenium Complex, [(NH3)5Ru–O–Ru(NH3)4–O–Ru(NH3)5]6+, also known as Ru-red, during the electro-driven water oxidation reaction, electrochemical in situ surface enhanced Raman spectroscopy (SERS) investigations have been conducted on an electrochemically roughened gold surface in acidic condition. It was previously described that on a basal plane pyrolitic graphite electrode in 0.1 M H2SO4 aqueous solution, Ru-red undergoes one electron oxidative conversion into a stable higher oxidation state Ruthenium Complex, Ru-brown, at <1.0 V (vs normal hydrogen electrode (NHE)), and this leads to water oxidation and dioxygen release, but the fate of Ru-red during electrochemistry was not studied in much detail. In this investigation, Ru-red dispersed in acid electrolyte and immobilized on a roughened gold electrode without Ru-red in solution has been subjected to anodic controlled potential experiments, and in situ SERS was carried out at various potentials in succession. The electrochemical SERS data obtained for Ru-red are also compared with in situ SERS results of an electrodeposited Ruthenium oxide thin film on the Au disk. Our study suggests that on a gold electrode in sulfuric acid solution containing Ru-red, one electron oxidative conversion of Ru-red to a higher oxidation state Ruthenium compound, Ru-brown, occurs at ca. 0.74 V (vs NHE), as supported by the electrochemical in situ SERS experiments. Moreover, at higher potentials and on Au disk, the Ru-red / Ru-brown are not stable and slowly decompose or electro-oxidize leading to deactivation of the tri-Ruthenium catalytic system in acidic medium. Copyright © 2013 John Wiley & Sons, Ltd.

Enzo Alessio - One of the best experts on this subject based on the ideXlab platform.

  • two point self coordination of a dizinc ii bispyridylporphyrin Ruthenium Complex leading selectively to a discrete molecular assembly solution and solid state characterization
    Chemistry: A European Journal, 2002
    Co-Authors: Elisabetta Iengo, Ennio Zangrando, Bruno Kieffer, Silvano Geremia, Roland Graff, Enzo Alessio
    Abstract:

    The dizinc(II) bispyridylporphyrin Ruthenium Complex trans,cis,cis[RuCl2(CO)2(Zn.4'-cisDPyP)2] (1Zn, 4'-cisDPyP = 5,10-bis(4'-pyridyl)-15,20-diphenylporphyrin) features two donor (the uncoordinated 4'-N(py) atoms) and two acceptor (the Zn atoms) sites and is thus a building block suited for two-point coordination. 1H NMR spectroscopy indicates that 1Zn self-assembles in solution through Zn-4'-N(py) interactions to yield selectively a highly symmetrical discrete species, in which all donor and all acceptor sites of 1Zn are mutually saturated. Single-crystal X-ray analysis established that this adduct is a dimeric species, (1Zn)2, with a global S4 symmetry, in which the four porphyrins have a propeller-like arrangement. The dimeric species (1Zn)2 is a meso form derived from the combination of two 1Zn units with opposite helical chirality. The geometry of this highly symmetrical tetraporphyrin assembly in solution, as determined by NMR spectroscopy, is essentially the same as that found in the solid state. Thus 1Zn is an unprecedented example of metal-containing self-complementary building block that selectively recognizes itself through four Zn-N(py) interactions, and thus yields a very stable and symmetrical dimeric species, (1Zn)2, that features four porphyrins and six metal atoms (two Ru and four Zn).

  • Two‐Point Self‐Coordination of a Dizinc(II) Bispyridylporphyrin Ruthenium Complex Leading Selectively to a Discrete Molecular Assembly: Solution and Solid‐State Characterization
    Chemistry: A European Journal, 2002
    Co-Authors: Elisabetta Iengo, Ennio Zangrando, Bruno Kieffer, Silvano Geremia, Roland Graff, Enzo Alessio
    Abstract:

    The dizinc(II) bispyridylporphyrin Ruthenium Complex trans,cis,cis[RuCl2(CO)2(Zn.4'-cisDPyP)2] (1Zn, 4'-cisDPyP = 5,10-bis(4'-pyridyl)-15,20-diphenylporphyrin) features two donor (the uncoordinated 4'-N(py) atoms) and two acceptor (the Zn atoms) sites and is thus a building block suited for two-point coordination. 1H NMR spectroscopy indicates that 1Zn self-assembles in solution through Zn-4'-N(py) interactions to yield selectively a highly symmetrical discrete species, in which all donor and all acceptor sites of 1Zn are mutually saturated. Single-crystal X-ray analysis established that this adduct is a dimeric species, (1Zn)2, with a global S4 symmetry, in which the four porphyrins have a propeller-like arrangement. The dimeric species (1Zn)2 is a meso form derived from the combination of two 1Zn units with opposite helical chirality. The geometry of this highly symmetrical tetraporphyrin assembly in solution, as determined by NMR spectroscopy, is essentially the same as that found in the solid state. Thus 1Zn is an unprecedented example of metal-containing self-complementary building block that selectively recognizes itself through four Zn-N(py) interactions, and thus yields a very stable and symmetrical dimeric species, (1Zn)2, that features four porphyrins and six metal atoms (two Ru and four Zn).

Licheng Sun - One of the best experts on this subject based on the ideXlab platform.

  • visible light driven water oxidation catalyzed by a highly efficient dinuclear Ruthenium Complex
    Chemical Communications, 2010
    Co-Authors: Lele Duan, Lianpeng Tong, Bjorn Akermark, Licheng Sun
    Abstract:

    Visible light-driven water oxidation has been achieved by the dinuclear Ruthenium Complex 1 with a high turnover number of 1270 in a homogeneous system in the presence of a Ru polypyridine Complex photosensitizer.

  • a new dinuclear Ruthenium Complex as an efficient water oxidation catalyst
    Inorganic Chemistry, 2009
    Co-Authors: Torbjorn Akermark, Lele Duan, Bjorn Akermark, Viktor Gyollai, Dapeng Zou, Lars Eriksson, Rong Zhang, Licheng Sun
    Abstract:

    A dinuclear Ruthenium Complex, which acts as a molecular catalyst for water oxidation, has been synthesized and characterized. The electronic and electrochemical properties were studied by UV−vis spectroscopy and cyclic voltammetry. The oxidation potentials of the Complex are significantly lowered by introducing a negatively charged carboxylate ligand, in comparison with those of the reported Complexes that have neutral ligands. The catalytic activity of the Complex toward water oxidation using Ce(NH4)2(NO3)6 as a chemical oxidant was investigated by means of an oxygen electrode and mass spectrometry. The turnover number of this catalyst with CeIV as the chemical oxidant was found to be ca. 1700. The mass spectroscopic analysis of the isotopomer distribution in oxygen evolved from 18O-labeled water indicates that O atoms in the evolved oxygen originate from water.

Masao Kaneko - One of the best experts on this subject based on the ideXlab platform.

  • redox reaction and charge transport of trinuclear Ruthenium Complex ru red as studied by potential step chronoamperospectrometry
    Electrochimica Acta, 1998
    Co-Authors: M Yagi, Kosato Kinoshita, K Nagoshi, Masao Kaneko
    Abstract:

    Abstract Redox reaction and charge transport of trinuclear Ruthenium Complex, Ru-red ([(NH3)5Ru(μ-O)Ru(NH3)4(μ-O)Ru(NH3)5]6+) were investigated in a Nafion (Nf) membrane as well as in a homogeneous aqueous solution using a potential-step chronoamperospectrometry (PSCAS) in addition to a cyclic voltammetry (CV). It has been shown in CV that Ru-red is oxidized to Ru-brown and then oxidatively transforms to stable redox species in the membrane during repetitive cyclic scans. In a potential-step from 0 to 0.5 V (vs SCE) in PSCAS, a reversible oxidation of Ru-red to Ru-brown was observed in both the membrane and solution. The charge transport based on Ru-red/Ru-brown took place in the membrane by both physical displacement of the Complex and charge hopping between them, while in the aqueous solution charge was transported only by physical displacement of the Complex. In a potential-step from 0.5 to 1.5 V (vs SCE), an irreversible oxidative transformation of Ru-brown takes place to produce the species which has almost no absorption in the visible region. The transformed species were stable and redox active in the membrane.

  • highly active electrocatalytic water oxidation system composed of trinuclear Ruthenium Complex supported on platinum black
    Chemistry Letters, 1995
    Co-Authors: Masayuki Yagi, Isamu Ogino, Atsushi Miura, Yoshimi Kurimura, Masao Kaneko
    Abstract:

    Trinuclear Ruthenium Complex, Ru-red ([(NH3)5Ru-O-Ru(NH3)4-O-Ru(NH3)5]6+) is adsorbed well onto the electrodeposited Pt-black, and the adsorbed Ru-red works as a highly active catalyst for electrochemical water oxidation