Serum Uric Acid and Iron Status: Exploring a Complex Interaction in Metabolic Syndrome Patients of Eastern India.

Background: Metabolic syndrome, a cluster of illnesses including insulin resistance, hyperlipidemia, hypertension, and central obesity, is affecting roughly a quarter of the world population. Dysregulation of iron homeostasis may be associated with insulin resistance, leading to metabolic syndrome. Uric acid is an antioxidant currently studied in relation to several metabolic disorders.

Redox reactions of a pyrazine-bridged Ru(edta) binuclear complex: spectrochemical, spectroelectrochemical and theoretical studies.

The redox reactions of a pyrazine-bridged binuclear [(edta)RupzRu(edta)] (edta = ethylenediaminetetraacetate; pz = pyrazine) have been investigated spectrochemically and spectroelectrochemically for the first time. The kinetics of the reduction of [(edta)RupzRu(edta)] (Ru-Ru) with the ascorbic acid anion (HA) was studied as a function of ascorbic concentration and temperature at a fixed pH 6.0.

Single-Atom Ru Catalyst-Decorated CNF(ZnO) Nanocages for Efficient H Evolution and CHOH Production.

The presence of transition-metal single-atom catalysts effectively enhances the interaction between the substrate and reactant molecules, thus exhibiting extraordinary catalytic performance. In this work, we for the first time report a facile synthetic procedure for placing highly dispersed Ru single atoms on stable CNF(ZnO) nanocages. We unravel the atomistic nature of the Ru single atoms in CNF(ZnO)/Ru systems using advanced HAADF-STEM, HRTEM, and XANES analytical methods.

A Personal Account on Inorganic Reaction Mechanisms.

The presented Review is focused on the latest research in the field of inorganic chemistry performed by the van Eldik group and his collaborators. The first part of the manuscript concentrates on the interaction of nitric oxide and its derivatives with biologically important compounds. We summarized mechanistic information on the interaction between model porphyrin systems (microperoxidase) and NO as well as the recent studies on the formation of nitrosylcobalamin (CblNO).

Ru(edta) complexes as molecular redox catalysts in chemical and electrochemical reduction of dioxygen and hydrogen peroxide: inner-sphere outer-sphere mechanism.

The reduction of molecular oxygen (O) and hydrogen peroxide (HO) by [Ru(edta)(pz)] (edta = ethylenediaminetetraacetate; pz = pyrazine) has been studied spectrophotometrically and kinetically in aqueous solution. Exposure of the aqua-analogue [Ru(edta)(HO)] to O and HO resulted in the formation of [Ru(edta)(HO)] species, with subsequent formation of the corresponding Ru[double bond, length as m-dash]O complex. A working mechanism for the O and HO reduction reactions mediated by the Ru(edta) complexes is proposed.

Reaction mechanisms relevant to the formation and utilization of [Ru(edta)(NO)] complexes in aqueous media.

The advancement of Ru(edta) complexes (edta = ethylenediamineteraacetate) mediated reactions, including NO generation and its utilization, has not been systematically reviewed to date. This review aims to report the research progress that has been made in exploring the application of Ru(edta) complexes in trapping and generation of NO. Furthermore, utilization of the potential of Ru(edta) complexes to mimic NO synthase and nitrite reductase activity, including thermodynamics and kinetics of NO binding to Ru(edta) complexes, their NO scavenging (in vitro), and antitumor activity will be discussed.

Inorganic reaction mechanisms. A personal journey.

This review covers highlights of the work performed in the van Eldik group on inorganic reaction mechanisms over the past two decades in the form of a personal journey. Topics that are covered include, from NO to HNO chemistry, peroxide activation in model porphyrin and enzymatic systems, the wonder-world of Ru(edta) chemistry, redox chemistry of Ru(iii) complexes, Ru(ii) polypyridyl complexes and their application, relevant physicochemical properties and reaction mechanisms in ionic liquids, and mechanistic insight from computational chemistry. In each of these sections, typical examples of mechanistic studies are presented in reference to related work reported in the literature.

Formation of [Ru(III)(edta)(SNO)](2-) in Ru(III)(edta)-Mediated S-Nitrosylation of Bisulfide Ion.

The reaction of hydrogen sulfide (H2S) and nitric oxide (NO) is of great physiological significance in human organisms. Our present studies show that Ru(III)(edta) (edta(4-) = ethylenediaminetetraacetate) mediates the S-nitrosylation of bisulfide ion (HS(-)) using NO to form [Ru(III)(edta)(SNO)](2-), the first-ever example of a ruthenium complex containing thionitrite (SNO(-)) in aqueous solution. The reaction product [Ru(III)(edta)(SNO)](2-) was characterized by IR, electron paramagnetic resonance, and electrospray ionization mass spectroscopy.

Ru(EDTA) mediated partial reduction of O2 by H2S.

An effective procedure for selective reduction of O2 to H2O2 exploring the use of hydrogen sulfide, an obnoxious industrial pollutant as reductant is reported herein. The reduction of [Ru(III)(EDTA)pz](-) (EDTA(4-) = ethylenediaminetetraacetate; pz = pyrazine) by hydrogen sulfide resulting in the formation of a red [Ru(II)(EDTA)pz](2-) complex (λmax = 462 nm) has been studied spectrophotometrically and kinetically using both rapid scan and stopped-flow techniques. The time course of the reaction was followed as a function of [HS(-)]i, pH (5.

Ru(III)(EDTA) mediated S-nitrosylation of cysteine by nitrite.

Reported here is the first example of a ruthenium(iii) complex [Ru(III)(EDTA)(H2O)](-) (EDTA(4-) = ethylenediaminetetraacetate) that mediates S-nitrosylation of cysteine in the presence of nitrite at pH 4.5 (acetate buffer) and results in the formation of [Ru(III)(EDTA)(SNOCy)](-). The kinetics of the reaction was studied by stopped-flow and rapid-scan spectrophotometry as a function of [Cysteine], [NO2(-)] and pH (3.

Direct evidence for catalase activity of [Ru(V)(edta)(O)](-).

Reported is the first example of a ruthenium(III) complex, Ru(III)(edta) (edta(4-) = ethylenediaminetetraacetate), that catalyzes the disproportion of H2O2 to O2 and water in resemblance to catalase activity, and shedding light on the possible mechanism of action of the [Ru(V)(edta)(O)](-) formed in the reacting system.

Nitrite reduction mediated by the complex RuIII(EDTA).

Reported is the first example of a ruthenium(III)-complex, Ru(III)(EDTA) (EDTA(4-) = ethylenediaminetetraacetate), that mediates O-atom transfer from nitrite to the biological thiols cysteine and glutathione, leading to the formation of [Ru(III)(EDTA)(NO(+))](0). However, at pH below 5.0, the coordinated nitrite ion in the [Ru(III)(EDTA)(NO2)](2-) complex undergoes proton-assisted decomposition, resulting in the formation of a [Ru(III)(EDTA)(NO(+))](0) species.

Ru(III)(edta) mediated oxidation of azide in the presence of hydrogen peroxide. Azide versus peroxide activation.

The [Ru(III)(edta)(H2O)](-) (edta(4-) = ethylenediaminetetraacetate) complex catalyzes the oxidation of azide (N3(-)) with H2O2, mimicking the action of metallo-enzymes such as catalase and peroxidase in biochemistry. The kinetics of the catalytic oxidation process was studied by using stopped-flow and rapid-scan spectrophotometry as a function of [Ru(III)(edta)], [H2O2], [N3(-)] and pH. The catalytic activity of the different oxidizing species produced in the reaction of [Ru(III)(edta)(H2O)](-) with H2O2 for the oxidation of azide was compared to the oxidation of coordinated azide in [Ru(III)(edta)N3](2-) by H2O2.

Oxidation of thiocyanate with H2O2 catalyzed by [Ru(III)(edta)(H2O)]-.

The [Ru(III)(edta)(H2O)](-) (edta(4-) = ethylenediaminetetraacetate) complex is shown to catalyze the oxidation of thiocyanate (SCN(-)) with H2O2 mimicking the action of peroxidases. The kinetics of the catalytic oxidation process was studied by using stopped-flow and rapid scan spectrophotometry as a function of [Ru(III)(edta)], [H2O2], [SCN(-)], pH (3.2-9.

Selective oxidation of thiourea with H(2)O(2) catalyzed by [Ru(III)(edta)(H(2)O)](-): kinetic and mechanistic studies.

Reported here is the first example of a ruthenium complex, [Ru(III)(edta)(H(2)O)](-) (edta(4-) = ethylenediaminetetraacetate), that catalyzes the oxidation of thiourea (TU) in the presence of H(2)O(2). The kinetics and mechanism of this reaction were investigated in detail by using rapid-scan spectrophotometry as a function of both the hydrogen peroxide and thiourea concentrations at pH 4.9 and 25 °C.

Peroxydisulfate activation by [RuII(tpy)(pic)(H2O)]+. Kinetic, mechanistic and anti-microbial activity studies.

The oxidation of [Ru(II)(tpy)(pic)H(2)O](+) (tpy = 2,2',6',2''-terpyridine; pic(-) = picolinate) by peroxidisulfate (S(2)O(8)(2-)) as precursor oxidant has been investigated kinetically by UV-VIS, IR and EPR spectroscopy. The overall oxidation of Ru(II)- to Ru(IV)-species takes place in a consecutive manner involving oxidation of [Ru(II)(tpy)(pic)H(2)O](+) to [Ru(III)(tpy)(pic)(OH)](+), and its further oxidation of to the ultimate product [Ru(IV)(tpy)(pic)(O)](+) complex. The time course of the reaction was followed as a function of [S(2)O(8)(2-)], ionic strength (I) and temperature.

Kinetics and mechanism of the [Ru(III)(edta)(H2O)](-)-mediated oxidation of cysteine by H2O2.

The kinetics and mechanism of the [Ru(III)(edta)(H(2)O)](-)-mediated oxidation of cysteine (RSH) by hydrogen peroxide (edta(4-) = ethylenediaminetetraacetate), were studied in detail as a function of both the hydrogen peroxide and cysteine concentrations at pH 5.1 and room temperature. The kinetic traces reveal clear evidence for a catalytic process in which hydrogen peroxide reacts directly with cysteine coordinated to the Ru(III)(edta) complex in the form of [Ru(III)(edta)SR](2-).

Remarkably high catalytic activity of the Ru(III)(edta)/H2O2 system towards degradation of the azo-dye Orange II.

The Ru(III)(edta)/H(2)O(2) system (edta(4-) = ethylenediaminetretaacetate) was found to degrade the azo-dye Orange II at remarkably high efficiency under ambient conditions. Catalytic degradation of the dye was studied by using rapid-scan spectrophotometry as a function of [H(2)O(2)], [Orange II] and pH. Spectral analyses and kinetic data point towards a catalytic pathway involving the rapid formation of [Ru(III)(edta)(OOH)](2-) followed by the immediate subsequent degradation of Orange II prior to the conversion of [Ru(III)(edta)(OOH)](2-) to [Ru(IV)(edta)(OH)](-) and [Ru(V)(edta)(O)](-)via homolysis and heterolysis of the O-O bond, respectively.

Redox reactions of a Ru(III)-edta complex with thioamino acids. Kinetic and mechanistic studies.

The kinetics of reduction of [Ru(III)(edta)pz]⁻ (edta⁴⁻ = ethylenediaminetetraacetate; pz = pyrazine) by thioamino acids (RSH = cysteine, glutathione) resulting in the formation of a red [Ru(II)(edta)pz]²⁻ species (λ(max) = 462 nm) has been studied spectrophotometrically using both conventional mixing and stopped-flow techniques. The time course of the reaction was followed as a function of [RSH], pH, temperature and pressure. Alkali metal ions were found to have a positive influence (K(+) > Na(+) > Li(+)) on the reaction rate.

Kinetics and mechanism of NO production in the Ru(III)-(edta) mediated oxidation of L-arginine with H(2)O(2).

The kinetics of the Ru(III)-(edta) (edta(4-) = ethylenediaminetetraacetate) catalyzed oxidation of l-arginine by H(2)O(2) mimicking the action of nitric oxide synthases (NOSs) has been studied spectrophotometrically. The time course of the reaction of [Ru(V)(edta)O](-) with l-arginine was followed at 390 nm under catalytic turn-over conditions. Formation of NO in the reacting system has been confirmed with an isolated nitric oxide free radical analyzer.

[Ru(III)(edta)(H(2)O)](-) mediated oxidation of hydroxyurea with H(2)O(2). Kinetic and mechanistic investigation.

Reported in this paper is the first example of a ruthenium complex, [Ru(III)(edta)(H(2)O)](-) (edta = ethylenediaminetetra-acetate), that catalyzes the oxidation of hydroxyurea in the presence of H(2)O(2), mimicking the action of peroxidase or catalase and shedding light on their possible mechanism of action.

Kinetics and mechanism of O-O bond cleavage in the reaction of [RuIII(edta)(H2O)]- with hydroperoxides in aqueous solution.

The reactions of [Ru(III)(edta)(H(2)O)](-) (1) (edta = ethylenediaminetetraacetate) with tert-butylhydroperoxide ((t)BuOOH) and potassium hydrogenpersulfate (KHSO(5)) were studied kinetically as a function of oxidant concentration and temperature (10-30 degrees C) at a fixed pH of 6.1 using stopped-flow techniques. Kinetic results were analyzed by using global kinetic analysis techniques.

A potential role for protein tyrosine phosphatase inhibition by a RuIII-edta complex (edta = ethylenediaminetetraacetate) in its biological activity.

[RuIII(edta)(OH2/OH)]1-/2- (edta = ethylenediaminetetraacetate) inhibits protein tyrosine phosphatase (PTP) at physiological pH values in a mechanism that involves binding of the Cys residue of the catalytic domain of the enzyme and similar interactions may be important in the anti-cancer properties of the active forms of many Ru pro-drugs.

Kinetics of the decoloration of reactive dyes over visible light-irradiated TiO(2) semiconductor photocatalyst.

Photocatalytic decoloration kinetics of triazine (Reactive Red 11, Reactive Red 2, and Reactive Orange 84) and vinylsulfone type (Reactive Orange 16 and Reactive Black 5) of reactive dyes have been studied spectrophotometrically by following the decrease in dye concentration with time. At ambient conditions, over 90-95% decoloration of above dyes have been observed upon prolonged illumination (15 h) of the reacting system with a 150 W xenon lamp. It was found that the decoloration reaction followed first-order kinetics.

Reaction of [RuIII(edta)(H2O)]- with H2O2 in aqueous solution. Kinetic and mechanistic investigation.

The reaction of [Ru(III)(edta)(H(2)O)](-) (1) (edta = ethylenediaminetetraacetate) with hydrogen peroxide was studied kinetically as a function of [H(2)O(2)], temperature (5-35 degrees C) and pressure (1-1300 atm) at a fixed pH of 5.1 using stopped-flow techniques. The reaction was found to consist of two steps involving the rapid formation of a [Ru(III)(edta)(OOH)](2-) intermediate which subsequently undergoes parallel heterolytic and homolytic cleavage to produce [(edta)Ru(V)=O](-) (45%) and [(edta)Ru(IV)(OH)](-) (55%), respectively.