The influence of NO-containing ruthenium complexes on mouse hippocampal evoked potentials in vitro

doi:10.1016/S0024-3205(01)00951-1

Life Sciences

Volume 68, Issue 13, 16 February 2001, Pages 1535-1544

https://doi.org/10.1016/S0024-3205(01)00951-1 Get rights and content

Abstract

The influence of different, nitric oxide-containing ruthenium complexes on the evoked potentials recorded from the CA1 region of the mouse hippocampus in vitro has been investigated. Of the compounds tested, only trans-[(NO)(P(OEt)₃)(NH₃)₄Ru](PF₆)₃ (1–2.5 mM) exerted a strong facilitatory action on the population spike, the EPSP, and the spontaneous activity. Its activity probably depends upon its ability to release NO following reduction. The phosphito ligand is important both in terms of adjusting the reduction potential of the complex to be biologically accessible and in labilizing the coordinated NO. The effects of this compound could not be reversed by perfusion. Scavenging NO in slices preincubated with oxyhemoglobin prior to the addition of this compound eliminated its neurophysiological effects. The control molecules trans-[(P(OEt)₃)₂(NH₃)₄Ru](PF₆)₂, trans-[(H₂O)(P(OEt)₃) (NH₃)₄Ru](PF₆)₃, and [(NO)(NH₃)₅Ru]Cl₃, which are structurally similar, but unable to generate NO, were ineffective. NaNO₂ suppressed neuronal firing. Attempts to induce Long-Term Potentiation (LTP) at the time of maximal effect of trans-[(NO)(P(OEt)₃)(NH₃)₄Ru](PF₆)₃ were unsuccessful, suggesting that the mechanism of amplification induced by trans-[(NO)(P(OEt)₃)(NH₃)₄Ru](PF₆)₃ and LTP may share common pathways.

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Cited by (39)

Synthesis, characterization, X-ray crystallography and stability in aqueous medium of trans-[Ru(CO)(NH<inf>3</inf>)<inf>4</inf>P(OH)<inf>3</inf>]2+
2017, Polyhedron
Here, we report the synthesis, characterization, crystal data and DFT calculation of a new water-soluble ruthenium(II) carbonyl complex. The trans-[Ru(CO)(NH₃)₄P(O)(OH)₂]Cl is a robust complex in aqueous media. The pK_a of 3.3 for the phosphorous acid ligand in this complex was measured by infrared spectroscopy. The trans-[Ru(CO)(NH₃)₄P(O)(OH)₂]⁺ exhibits just two slow reactions at pH 7.5: CO–Ru–P(O)(OH)₂ to CO–Ru–(O)P(OH)₂ isomerization (k = 1.1 × 10⁻⁵ s⁻¹ at 25 °C) and subsequent P(O)(OH)₂ dissociation (k = 1.7 × 10⁻⁷ s⁻¹ at 25 °C). The formation of O-bonded trans-[Ru(CO)(NH₃)₄(O)P(OH)₂]⁺ was supported by IR, UV–Vis and ³¹P NMR spectroscopies and DFT calculations.
Trans-[Ru(NO)(NH<inf>3</inf>)P(O-)(OEt)<inf>2</inf>] 2+: A new and robust NO/HNO-donor in aqueous media
2014, Inorganica Chimica Acta
This study describes the synthesis and reactivity in aqueous media of a new potential NO/HNO-donor: trans-[Ru(NO)(NH₃)₄P(O⁻)(OEt)₂](PF₆)₂. This compound exhibits a remarkable robustness over a wide range of pH relative to other similar ruthenium phosphorus nitrosyl complexes. At pH 3.0 and 25 °C, trans-[Ru(NO)(NH₃)₄P(O⁻)(OEt)₂](PF₆)₂ decays, yielding free diethyl phosphite with a half-life of 9 days (k = 8.9 × 10⁻⁷ s⁻¹). At pH 7.5 and 25 °C, this complex is competitively consumed by diethyl phosphite dissociation (k = 5.15 × 10⁻⁵ s⁻¹) and nucleophilic attack at the nitrosyl group (k = 7.25 × 10⁻⁵ s⁻¹). Nevertheless, the trans-[Ru(NO)(NH₃)₄P(O⁻)(OEt)₂](PF₆)₂ exhibits a half-life of 1.5 h (pH 7.5 and 25 °C) for delivering NO/HNO by electrochemical activation at potentials of −0.50 and −0.80 V versus SCE. The NO liberation from trans-[Ru(NO)(NH₃)₄P(O⁻)(OEt)₂]⁺ ion occurs with k_–_NO = 0.24 ± 0.01 s⁻¹, and electrochemical data indicate that k_–HNO ≫ k_–NO.
Electrochemical and Monte Carlo studies of self-assembled trans-[Fe(cyclam)(NCS)<inf>2</inf>]+ complex ion on gold surface as electrochemical sensor for nitric oxide
2013, Electrochimica Acta
Citation Excerpt :
Due to these motifs, it is currently crescent the interest to study metal macrocyclic complexes as modifier of the electrode surface in order to obtain an electrochemical sensor for NO and metallophthalocyanine and metalloporphyrin are the most commonly used for this intention [8–15]. Our group has reported that Ru-based [16–21] and Fe-based [22–26] complexes can act as donors or as scavengers of nitric oxide because they are know to present reversible binding with NO. In addition, Mori et al. [27] have shown that gold electrodes modified with molybdenum oxide and trans-[Ru(NH3)4(SO4)4pic]+ can be applied to monitor real-time changes in NO concentrations at low levels. Recently, we reported that the modification of the gold electrode by the trans-Ru[(NH3)4(Ist)SO4]+ ion complex, where (Ist) is the thioisonicotinamide ligand, has potential to be applied as a sensor for NO [28].
Modification of gold electrode by self-assembled trans-[Fe(cyclam)(NCS)₂]⁺ complex ion to produce an electrochemical sensor for nitric oxide detection was investigated. Dopamine, serotonin and nitrite were examined as interferents. The synthesized complex was characterized by X-ray diffraction and by infrared spectroscopy. The modified electrode was characterized by cyclic voltammetry and by surface enhanced Raman spectroscopy, analytical curves were obtained by square wave voltammetry and Monte Carlo calculations were made to model the interaction of NO molecules with the unmodified and modified surfaces. The complex has distorted octahedron geometry with the thiocyanate groups bonded to the iron ion by the nitrogen atom and in the trans orientation. SERS spectrum and Monte Carlo calculations supported that the complex ion is adsorbed on Au surface from the Au-S bond. The electrochemical current for NO oxidation on the modified electrode was higher than that presented by the bare Au electrode and a good correlation was presented by the experimental analytical curve and the calculated Monte Carlo interaction energy versus amount NO molecules plot. The Monte Carlo calculations indicated that the higher current response for NO oxidation on the Au/trans-[Fe(cyclam)(NCS)₂]⁺ surface was due to the stronger interaction of the NO molecules with complex adsorbed on the Au surface than the interaction of NO with the bare Au surface. The theoretical analyses also revealed that NO molecules cluster on Au surface. Dopamine, serotonin and nitrite were interferents for the detection of NO with dopamine and serotonin was less significant interferents than the nitrite. The proposed modified electrode presented good electrochemical stability, detection limit and quantification limit of 5.15 × 10⁻⁸ mol L⁻¹ and 1.72 × 10⁻⁷, respectively, which were about one order of magnitude lesser than the corresponding values obtained for the bare Au electrode. The results indicated that the proposed electrode has potential to be applied as a sensor for NO detection.
Biological activity of ruthenium nitrosyl complexes
2012, Nitric Oxide - Biology and Chemistry
Citation Excerpt :
Central nervous neurons can be excited by different factors, for instance, electrical stimulus, which can be used at high or low frequencies, resulting in long-term potentiation (LTP) [122] or long-term depression (LTD) [123] of the synaptic response. In the hippocampus, nNOS and eNOS are abundant [124], and NO produced in this area can act as a mediator in LTP [120]. Therefore, the trans-[RuII(NO+)(NH3)4P(OEt)3](PF6)3 compound was investigated as an NO-donor in mice hippocampus slices in vitro, facilitating the population spike [120].
Nitric oxide plays an important role in various biological processes, such as neurotransmission, blood pressure control, immunological responses, and antioxidant action. The control of its local concentration, which is crucial for obtaining the desired effect, can be achieved with exogenous NO-carriers. Coordination compounds, in particular ruthenium(III) and (II) amines, are good NO-captors and -deliverers. The chemical and photochemical properties of several ruthenium amine complexes as NO-carriers in vitro and in vivo have been reviewed. These nitrosyl complexes can stimulate mice hippocampus slices, promote the lowering of blood pressure in several in vitro and in vivo models, and control Trypanosoma cruzi and Leishmania major infections, and they are also effective against tumor cells in different models of cancer. These complexes can be activated chemically or photochemically, and the observed biological effects can be attributed to the presence of NO in the compound. Their efficiencies are explained on the basis of the [Ru^IINO⁺]³⁺/[Ru^IINO⁰]²⁺ reduction potential, the specific rate constant for NO liberation from the [RuNO]²⁺ moiety, and the quantum yield of NO release.
Study of a gold electrode modified by trans-[Ru(NH<inf>3</inf>) <inf>4</inf>(Ist)SO<inf>4</inf>]+ to produce an electrochemical sensor for nitric oxide
2011, Electrochimica Acta
Citation Excerpt :
RuCl3·xH2O (Aldrich), thioisonicotinamide (Ist) (Aldrich), Na2SO4 (J.T. Baker) and sulphuric acid (Suprapur – Merck) were used as received. The trans-Ru[(NH3)4(Ist)SO4]Cl complex was prepared according to procedures in the literature for similar compounds [36–41]. All other chemicals were of analytical grade and Millipore-Q purified water was used to prepare all solutions, which were deaerated with high-purity N2 (White Martins SS) prior to the experiments.
The modification of a gold electrode surface by electropolymerization of trans-[Ru(NH₃)₄(Ist)SO₄]⁺ to produce an electrochemical sensor for nitric oxide was investigated. The influence of dopamine, serotonin and nitrite as interferents for NO detection was also examined using square-wave voltammetry (SWV). The characterization of the modified electrode was carried out by cyclic voltammetry, electrochemical quartz crystal microbalance (EQCM) and SERS techniques. The gold electrode was successfully modified by the trans-[Ru(NH₃)₄(Ist)SO₄]⁺ complex ion using cyclic voltammetry. The experiments show that a monolayer of the film is achieved after ten voltammetric cycles, that NO in solution can coordinate to the metal present in the layer, that dopamine, serotonin and nitrite are interferents for the detection of NO, and that the response for the nitrite is much less significant than the responses for dopamine and serotonin. The proposed modified electrode has the potential to be applied as a sensor for NO.
Antileishmanial activity of ruthenium(II)tetraammine nitrosyl complexes
2010, European Journal of Medicinal Chemistry
The complexes trans-[Ru(NO)(NH₃)₄L](X)₃ (X = BF₄⁻, PF₆⁻ or Cl⁻ and L = N-heterocyclic ligands, P(OEt)₃, SO₃⁻²), and [Ru(NO)Hedta)] were shown to exhibit IC_50pro in the range of 36 (L = imN) to 5000 μM (L = imC). The inhibitory effects of trans-[Ru(NO)(NH₃)₄imN](BF₄)₃ and of the Angeli’s salt on the growth of the intramacrophage amastigote form studied were found to be similar while the trans-[Ru(NH₃)₄imN(H₂O)]²⁺ complex was found not to exhibit any substantial antiamastigote effect. The trans-[Ru(NO)(NH₃)₄imN](BF₄)₃ compound, administered (500 nmol kg⁻¹ day⁻¹) in BALB/c mice infected with Leishmania major, was found to exhibit a 98% inhibition on the parasite growth. Furthermore, this complex proved to be at least 66 times more efficient than glucantime in in vivo experiments.

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Cited by (39)

Synthesis, characterization, X-ray crystallography and stability in aqueous medium of trans-[Ru(CO)(NH<inf>3</inf>)<inf>4</inf>P(OH)<inf>3</inf>]<sup>2+</sup>

Trans-[Ru(NO)(NH<inf>3</inf>)P(O<sup>-</sup>)(OEt)<inf>2</inf>] <sup>2+</sup>: A new and robust NO/HNO-donor in aqueous media

Electrochemical and Monte Carlo studies of self-assembled trans-[Fe(cyclam)(NCS)<inf>2</inf>]<sup>+</sup> complex ion on gold surface as electrochemical sensor for nitric oxide

Biological activity of ruthenium nitrosyl complexes

Study of a gold electrode modified by trans-[Ru(NH<inf>3</inf>) <inf>4</inf>(Ist)SO<inf>4</inf>]<sup>+</sup> to produce an electrochemical sensor for nitric oxide

Antileishmanial activity of ruthenium(II)tetraammine nitrosyl complexes

Original articlesThe influence of NO-containing ruthenium complexes on mouse hippocampal evoked potentials in vitro

Abstract

Original articles
The influence of NO-containing ruthenium complexes on mouse hippocampal evoked potentials in vitro