Correlations in the EPR State Observables.

The identification and physical interpretation of arbitrary quantum correlations are not always effortless. Two features that can significantly influence the dispersion of the joint observable outcomes in a quantum bipartite system composed of systems I and II are: (a) All possible pairs of observables describing the composite are equally probable upon measurement, and (b) The absence of concurrence (positive reinforcement) between any of the observables within a particular system; implying that their associated operators do not commute. The so-called EPR states are known to observe (a). Here, we demonstrate in very general (but straightforward) terms that they also satisfy condition (b), a relevant technical fact often overlooked. As an illustration, we work out in detail the three-level systems, i.e., qutrits. Furthermore, given the special characteristics of EPR states (such as maximal entanglement, among others), one might intuitively expect the CHSH correlation, computed exclusively for the observables of qubit EPR states, to yield values greater than two, thereby violating Bell's inequality. We show such a prediction does not hold true. In fact, the combined properties of (a) and (b) lead to a more limited range of values for the CHSH measure, not surpassing the nonlocality threshold of two. The present constitutes an instructive example of the subtleties of quantum correlations.

Biological activity of mixed chelate copper(II) complexes, with substituted diimine and tridentate Schiff bases (NNO) and their hydrogenated derivatives as secondary ligands: Casiopeína's fourth generation.

We synthesize and characterize nine copper(II) compounds. Four with general formula [Cu(NNO)(NO3)] and five mixed chelates [Cu(NNO)(N-N)]+, where NNO corresponds to asymmetric salen ligands (E)-2-((2-(methylamino)ethylimino)methyl)phenolate (L1) and (E)-3-((2-(methylamino)ethylimino)methyl)naphthalenolate (LN1); and their hydrogenated derivatives 2-((2-(methylamino)ethylamino)methyl)phenolate (LH1) and 3-((2-(methylamino)ethylamino)methyl)naphthalenolate (LNH1); and N-N correspond to 4,4'-dimethyl-2,2'-bipiridyne(dmbpy) or 1,10-phenanthroline (phen). Using EPR, the geometries of the compounds in solution in DMSO were assigned, [Cu(LN1)(NO3)] and [Cu(LNH1)(NO3)] a square-planar, [Cu(L1)(NO3)], [Cu(LH1)(NO3)], [Cu(L1)(dmby)]+ and [Cu(LH1)(dmby)]+ a square-based pyramid; and [Cu(LN1)(dmby)]+, [Cu(LNH1)(dmby)]+ and [Cu(L1)(phen)]+ and elongated octahedral. By X-ray it was observed that [Cu(L1)(dmby)]+ and. [Cu(LN1)(dmby)]+ presented a square-based pyramidal, and [Cu(LN1)(NO3)]+ a square-planar geometry. The electrochemical study showed that copper reduction process is a quasi-reversible system, where the complexes with hydrogenated ligands were less oxidizing. The cytotoxicity of the complexes was tested by MTT assay, all the compounds showed biological activity in HeLa cell line, the mixed compounds were the more active ones. Naphthalene moiety, imine hydrogenation and aromatic diimine coordination, increased biological activity. A structure-activity relationships were found: Log(IC50) =  - 1.01(Epc) - 0.35(Conjugated Rings) + 0.87, for Schiff base complexes and Log(IC50) = 0.078(Epc) - 0.32(Conjugated Rings) + 1.94, for hydrogenated complexes; the less oxidizing species with a great number of conjugated rings presented the best biological activity. Complexes-DNA binding constants were obtained by uv-vis studies using CT-DNA, the results suggested that the complexes can interact through the grooves, except the phenanthroline mixed complex that intercalate with DNA. Gel electrophoresis study with pBR 322 showed that compounds can produce changes in the form of DNA and some complexes can cleave DNA in the presence of H2O2.

Molecular and kinetic properties of copper nitrite reductase from Sinorhizobium meliloti 2011 upon substituting the interfacial histidine ligand coordinated to the type 2 copper active site for glycine.

A copper-containing nitrite reductase catalyzes the reduction of nitrite to nitric oxide in the denitrifier Sinorhizobium meliloti 2011 (SmNirK), a microorganism used as bioinoculant in alfalfa seeds. Wild type SmNirK is a homotrimer that contains two copper centers per monomer, one of type 1 (T1) and other of type 2 (T2). T2 is at the interface of two monomers in a distorted square pyramidal coordination bonded to a water molecule and three histidine side chains, H171 and H136 from one monomer and H342 from the other. We report the molecular, catalytic, and spectroscopic properties of the SmNirK variant H342G, in which the interfacial H342 T2 ligand is substituted for glycine. The molecular properties of H342G are similar to those of wild type SmNirK. Fluorescence-based thermal shift assays and FTIR studies showed that the structural effect of the mutation is only marginal. However, the kinetic reaction with the physiological electron donor was significantly affected, which showed a âˆ¼ 100-fold lower turnover number compared to the wild type enzyme. UV-Vis, EPR and FTIR studies complemented with computational calculations indicated that the drop in enzyme activity are mainly due to the void generated in the protein substrate channel by the point mutation. The main structural changes involve the filling of the void with water molecules, the direct coordination to T2 copper ion of the second sphere aspartic acid ligand, a key residue in catalysis and nitrite sensing in NirK, and to the loss of the 3 N-O coordination of T2.

Scavenging of reactive species probed by EPR and ex-vivo nanomolar reduction of lipid peroxidation of manganese complexes.

Antioxidant activity toward H2O2, anion radical superoxide, hydroxyl and DPPH (2,2-diphenyl-1-picrylhydrazyl) of two manganese complexes [Mn(III)(bpa)2]Cl.H2O (1) and [(Cl)Mn(µ-hbpclnol)(µ-bpclnol)Mn](ClO4).3H2O (2) (hbpa = (2-hydroxybenzyl-2-pyridylmethyl)amine and h2bpclnol = (N-(2-hydroxybenzyl)-N-(2-pyridylmethyl)[(3-chloro)(2-hydroxy)]propylamine) are presented. X-ray diffraction studies were performed for complex (1). Both complexes presented similar or better activities than reference complex [Mn(salen)Cl], when the interaction between them and ROS (H2O2, O2•- and •OH), was monitored, by EPR (Electron Paramagnetic Resonance), in PBS, DMSO and water. The antioxidant activity rank of complexes toward •OH, generated by Fenton reaction and monitored by EPR, is (2) > (1) > [Mn(salen)Cl], in water (0.1% of DMSO for each complex), with the values of the IC50 of 7.2 (±1.6), 15.5 (±1.8) and 29.1 (±2.01) µM respectively. EPR data presented herein suggest that complex (2) presents the better scavenging activity toward hydroxyl, being in good agreement with TBARS assay results, in which complex (2) presented the best inhibitory activity toward lipid peroxidation, employing Swiss mice liver homogenate tissue model. IC50 values obtained from the interaction between these complexes and hydroxyl, using TBARS method, were: 0.88 (± 0.029); 0.73 (± 0.01) and 42.7 (± 3.5) nM, respectively for (1), (2) and [Mn(salen)Cl]. Complexes (1) and (2) are regulating the lipid homeostasis, protecting the tissue from the lipid peroxidation, in nanomolar scale, motivating in vivo studies. Redox properties and radical scavenging activity of complexes toward DPPH are non-linear and solvent dependent. Furthermore, the monitoring of antioxidant activity probed by EPR could be a fair and appropriate study to guide more advanced investigations.

ROS scavenging of SOD/CAT mimics probed by EPR and reduction of lipid peroxidation in S. cerevisiae and mouse liver, under severe hydroxyl radical stress condition.

The interaction between CuII, FeIII and MnII complexes, derived from the ligands 1-[bis(pyridine-2-ylmethyl)amino]-3-chloropropan-2-ol (hpclnol) and bis(pyridine-2-ylmethyl)amine (bpma), and the free radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH) and reactive oxygen species (ROS), was investigated by colorimetric and EPR (Electron Paramagnetic Resonance) techniques. A comparison between these results and those reported to [Mn(salen)Cl] or EUK-8 was also addressed. EPR studies allowed us the identification of intermediates species such as superoxide­copper(I) and superoxide­copper(II), a mixed-valence FeIIIFeII species and a 16-line feature attributed to MnIII-oxo-MnIV species. The biomarker malondialdehyde (MDA) was determined by TBARS assay in S. cerevisiae cells, and the determination of the IC50 indicate that the antioxidant activity shown dependence on the metal center (CuII ≈ FeIII > MnII ≈ [Mn(salen)Cl]. The lipid peroxidation attenuation was also investigated in liver homogenates obtained from Swiss mice and the IC50 values were in the nanomolar concentrations. We demonstrated here that all the complexes interact with the free radical DPPH and with ROS (H2O2, O2•- and hydroxyl radical), enhancing the cellular protection against oxidative stress generated by hydroxyl radical, employing two experimental model systems, S. cerevisiae (in vivo) and mouse liver (ex vivo).

Carotenoids from Haloarchaea: Extraction, Fractionation, and Characterization.

Carotenoids are bioactive molecules known to promote human health. Many extreme halophilic archaea synthesize carotenoids, mainly represented by C50 bacterioruberin (BR) and its derivatives. BR has a potent antioxidant capacity, even higher than that of ß-carotene, thus, there is an increasing interest to advance the study of its biological properties as well as to extend its current applications. Here, we describe a procedure to extract and characterize carotenoids (enriched in BR) from haloarchaea using a "hyperpigmented" genetically modified strain of Haloferax volcanii.

Detection of radicals produced during electro-oxidation of atrazine using commercial DSA®-Cl2 in methanol media: Keys to understand the process.

This work reports the radicals detected and identified during the degradation of atrazine in methanol medium in the presence and absence of different proportions of water (0%, 5%, and 10%). The determination of these radicals is an important step to understand the electrolysis processes in methanol medium and contribute to clarify the degradation mechanism. Furthermore, the parameters for the successful removal of the contaminant were optimized and the results showed that the application of the technique led to the removal of nearly 99.8% of atrazine after 1 h of electrolysis. The oxidation kinetics was found to be very fast and most of the atrazine molecule in the medium was degraded in the first hour of electrolysis. The results obtained from a thorough analysis conducted with a view to evaluating the effects of different current densities and initial pH values on atrazine degradation showed that the application of higher current densities resulted in lower energy consumption, as this led to faster removal of atrazine. Additionally, the initial pH of the solution was found to favor the formation of different species of active chlorine. The radicals formed during the electro-oxidation process were detected by electron paramagnetic resonance spectroscopy and include hydroxyl, methoxy and hydroxymethyl. The use of methanol for the degradation of pollutants is a highly promising technique and this work shows that the identification of the different radicals formed in the process can be the key to understanding the degradation mechanism.

Solid-State Characterization of Acetylpyridine Copper Complexes for the Activation of H2 O2 in Advanced Oxidation Processes.

This work describes the synthesis of 4-(4-AcPy) and 3-acetylpyridine (3-AcPy) copper soluble complexes for the activation of hydrogen peroxide and the concomitant generation of reactive oxygen species (ROS). Given the paramagnetic effects of copper ions in the Nuclear Magnetic Resonance (NMR) lines, we aimed at demonstrating that the combination of high-resolution 2D solid-state NMR experiments, Electron Paramagnetic Resonance (EPR), single-crystal X-ray crystallography and Density Functional Theory (DFT) calculations allows a detailed study of the chemical structure of the ligands and the surrounding metal ions. The copper complexes synthesized with CuCl2 were useful for the activation of H2 O2 during which the only ROS was the hydroxyl one, as demonstrated by EPR experiments. A removal of methyl orange (MO) azo-dye higher than 85 % was achieved in 200 minutes, combining 1.7 mM of copper complexes with 60 mM of H2 O2 and 40 µM of MO.

Polyphenolic Composition and Antioxidant Activity (ORAC, EPR and Cellular) of Different Extracts of Argylia radiata Vitroplants and Natural Roots.

Plant biochemistry studies have increased in recent years due to their potential to improve human health. Argylia radiata is an extremophile plant with an interesting polyphenolic profile. However, its biomass is scarce and occasionally available. Argylia in vitro biomass was obtained from tissue culture and compared with in vivo roots regarding its polyphenolic and flavonoid content. Different solvents were used to prepare extracts from the in vitro tissue of callus and aerial plant organs and in vivo roots. UPLC-MS/MS was used to assess the chemical composition of each extract. ORAC-FL and scavenging of free radicals (DPPH and OH) methods were used to determine the antioxidant capacity of extracts. Furthermore, the biological activity of the extracts was established using the cellular antioxidant activity method. The vitroplants were a good source of polyphenols (25-68 mg GAE/100 g tissue FW), and methanol was the most efficient solvent. Eight polyphenolic compounds were identified, and their antioxidant properties were investigated by different chemical methods with EPR demonstrating its specific scavenging activity against free radicals. All extracts showed cellular dose-dependent antioxidant activity. The methanolic extract of vitroplants showed the highest cellular antioxidant activity (44.6% and 51%) at 1 and 10 µg/mL of extract, respectively. Vitroplants of A. radiata are proposed as a biotechnological product as a source of antioxidant compounds with multiple applications.

Nocellara Del Belice (Olea europaea L. Cultivar): Leaf Extract Concentrated in Phenolic Compounds and Its Anti-Inflammatory and Radical Scavenging Activity.

Olea europaea L. is a plant belonging to the Oleaceae family, widely grown around the Mediterranean Basin and its leaves are a source of phenolic compounds with antioxidant and anti-inflammatory capacity. Among these, oleuropein and luteolin-7-O-glucoside represent two major polyphenolic compounds in olive-leaf extract. Herein, a polystyrene resin was used to recover the polyphenolic fraction from the acetone-water leaf extract from Nocellara del Belice cultivar, which showed the higher level of analysed bioactive compounds, compared to Carolea cultivar. The antioxidant activity of the extract concentrated in phenolic compounds (OLECp) was evaluated through a classical assay and electron paramagnetic resonance (EPR) for DPPH and hydroxyl radicals scavenging. Thus, the anti-inflammatory activity and the potential beneficial effects in reducing lipid accumulation in an in vitro model of NAFLD using McA-RH7777 cells exposed to oleic acid (OA) were evaluated. Nile Red and Oil Red O have been used to stain the lipid accumulation, while the inflammatory status was assessed by Cytokines Bioplex Assay. OLECp (TPC: 92.93 ± 9.35 mg GAE/g, TFC: 728.12 ± 16.04 mg RE/g; 1 g of extract contains 315.250 mg of oleuropein and 17.44 mg of luteolin-7-O-glucoside) exerted a good radical scavenging capability (IC50: 2.30 ± 0.18 mg/mL) with a neutralizing power against DPPH and hydroxyl radicals, as confirmed by the decreased signal area of the EPR spectra. Moreover, OLECp at concentration of 25, 50 and 100 µg/mL counteracted the intracellular inflammatory status, as result of decreased intracellular lipid content. Our results highlighted the multiple properties and applications of an O. europaea extract concentrated in polyphenols, and the possibility to formulate novel nutraceuticals with antioxidant properties, destined to ameliorate human health.

Proposal to Test a Transient Deviation from Quantum Mechanics' Predictions for Bell's Experiment.

Quantum mechanics predicts correlations between measurements performed in distant regions of a spatially spread entangled state to be higher than allowed by intuitive concepts of Locality and Realism. These high correlations forbid the use of nonlinear operators of evolution (which would be desirable for several reasons), for they may allow faster-than-light signaling. As a way out of this situation, it has been hypothesized that the high quantum correlations develop only after a time longer than L/c has elapsed (where L is the spread of the entangled state and c is the velocity of light). In shorter times, correlations compatible with Locality and Realism would be observed instead. A simple hidden variables model following this hypothesis is described. It is based on a modified Wheeler-Feynman theory of radiation. This hypothesis has not been disproved by any of the experiments performed to date. A test achievable with accessible means is proposed and described. It involves a pulsed source of entangled states and stroboscopic record of particle detection during the pulses. Data recorded in similar but incomplete optical experiments are analyzed, and found consistent with the proposed model. However, it is not claimed, in any sense, that the hypothesis has been validated. On the contrary, it is stressed that a complete, specific test is absolutely needed.

Reactive Oxygen Species in Emulated Martian Conditions and Their Effect on the Viability of the Unicellular Alga Scenedesmus dimorphus.

Formation of oxygen-based free radicals from photochemical decomposition of hydrogen peroxide (H2O2) on Mars may be a key factor in the potential survival of terrestrial-like organisms on the red planet. Martian conditions that generate reactive oxygen species involve the decomposition of H2O2 at temperatures of around 278 K under relatively high doses of C-band ultraviolet radiation (UVC). This process is further amplified by the presence of iron oxides and perchlorates. Photosynthetic organisms exhibit a number of evolutionary traits that allow them to withstand both oxidative stress and UVC radiation. Here, we examine the effect of free radicals produced by the decomposition of H2O2 under emulated martian conditions on the viability of Scenedesmus dimorphus, a unicellular alga that is resistant to UVC radiation and varying levels of perchlorate and H2O2, both of which are present on Mars. Identification and quantification of free radicals formed under these conditions were performed with Electron Paramagnetic Resonance spectroscopy. These results were correlated with the viability of S. dimorphus, and the formation of oxygen-based free radicals and survival of the alga were found to be strongly dependent on the amount of H2O2 available. For H2O2 amounts close to those present in the rarefied martian environment, the products of these catalytic reactions did not have a significant effect on the algal population growth curve.

A bioinspired nitrone precursor to a stabilized nitroxide radical.

Nitrones derived from natural antioxidants are emerging as highly specific therapeutics against various human diseases, including stroke, neurodegenerative pathologies, and cancer. However, the development of useful pseudo-natural nitrones requires the judicious choice of a secondary metabolite as the precursor. Betalains are nitrogen-containing natural pigments that exhibit marked antioxidant capacity and pharmacological properties and, hence, are ideal candidates for designing multifunctional nitrones. In this work, we describe the semisynthesis and properties of a biocompatible and antioxidant betalain-nitrone called OxiBeet. This bio-based compound is a better radical scavenger than ascorbic acid, gallic acid, and most non-phenolic antioxidants and undergoes concerted proton-coupled electron transfer. The autoxidation of OxiBeet produces a persistent nitroxide radical, which, herein, is studied via electron paramagnetic resonance spectroscopy. In addition, femtosecond transient absorption spectroscopy reveals that excited state formation is not required for the oxidation of OxiBeet. The results are compared with those obtained using betanin, a natural betalain, and pBeet, the imine analog of OxiBeet. The findings of this study will enable the development of antioxidant and spin-trap nitrones based on the novel N-oxide 1,7-diazaheptamethinium scaffold and betalain dyes with enhanced hydrolytic stability in aqueous alkaline media.

Small interfering RNA for cancer treatment: overcoming hurdles in delivery.

In many ways, cancer cells are different from healthy cells. A lot of tactical nano-based drug delivery systems are based on the difference between cancer and healthy cells. Currently, nanotechnology-based delivery systems are the most promising tool to deliver DNA-based products to cancer cells. This review aims to highlight the latest development in the lipids and polymeric nanocarrier for siRNA delivery to the cancer cells. It also provides the necessary information about siRNA development and its mechanism of action. Overall, this review gives us a clear picture of lipid and polymer-based drug delivery systems, which in the future could form the base to translate the basic siRNA biology into siRNA-based cancer therapies.

Dating and determination of firing temperature of ancient potteries from Yumina archaeological site, Arequipa, Peru.

Pottery fragments from the Yumina archaeological site, Arequipa, Peru, were dated by means of thermoluminescence (TL) and optically stimulated luminescence (OSL). Electron paramagnetic resonance (EPR) technique was used to study the firing temperature using the iron signal (Fe3+) as a firing temperature reference. The ages of the samples were found to be between 1190 ±â€¯30 and 1240 ±â€¯80 years (777 ±â€¯80 and 827 ±â€¯30 A.D.) determined by both techniques. The firing temperature of ceramics was found to be around 550  ± 50 °C. Our study, based on the combination of TL and OSL techniques to study Yumina archaeological site pottery, will be helpful for archaeologists in Peru. With the results of this investigation, we can understand the chronology and determine the areas of dispersion and density of the archaeological occupation in the Arequipa Valley. In addition, the calculated ages are consistent with the occupation period of the Yumina archaeological site estimated by stratigraphic analysis of the potteries.

Dating of carbonate covering cave paintings at peruaçu, Brazil by TL and EPR methods.

In the present work, carbonate samples covering wall painting of four points in the same site found at Peruaçu National Park in the extreme northwest of the state of Minas Gerais, Brazil, has been investigated and dated by thermoluminescence (TL) and electron paramagnetic resonance (EPR) techniques. The EPR spectrum of the carbonate samples presented the typical six signals due to Mn2+ ion and signals around g~2.0 due to SO2- and CO2-. The thermal stability and dose response of the EPR signals were found to be suitable for an age determination using the center due to CO2-. The carbonate sample exhibits TL peaks at approximately 350 °C. TL and EPR dating of the carbonate samples that covered the cave paintings gave an age of 33.13 to 48.40 ka. This series of dating data indicate that in the region about 220-250 km from the coast and extending from the State of Piaui, Bahia to Minas Gerais people lived around 50000 years ago.

Quantification of carbonate radical formation by the bicarbonate-dependent peroxidase activity of superoxide dismutase 1 using pyrogallol red bleaching.

Carbonate radicals (CO3-) are generated by the bicarbonate-dependent peroxidase activity of cytosolic superoxide dismutase (Cu,Zn-SOD, SOD-1). The present work explored the use of bleaching of pyrogallol red (PGR) dye to quantify the rate of CO3- formation from bovine and human SOD-1 (bSOD-1 and hSOD-1, respectively). This approach was compared to previously reported methods using electron paramagnetic resonance spin trapping with DMPO, and the oxidation of ABTS (2,2-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid). The kinetics of PGR consumption elicited by CO3- was followed by visible spectrophotometry. Solutions containing PGR (5-200 µM), SOD-1 (0.3-3 µM), H2O2 (2 mM) in bicarbonate buffer (200 mM, pH 7.4) showed a rapid loss of the PGR absorption band centered at 540 nm. The initial consumption rate (Ri) gave values independent of the initial PGR concentration allowing an estimate to be made of the rate of CO3- release of 24.6 ±â€¯4.3 µM min-1 for 3 µM bSOD-1. Both bSOD-1 and hSOD-1 showed a similar peroxidase activity, with enzymatic inactivation occurring over a period of 20 min. The single Trp residue (Trp32) present in hSOD-1 was rapidly consumed (initial consumption rate 1.2 ±â€¯0.1 µM min-1) with this occurring more rapidly than hSOD-1 inactivation, suggesting that these processes are not directly related. Added free Trp was rapidly oxidized in competition with PGR. These data indicate that PGR reacts rapidly and efficiently with CO3- resulting from the peroxidase activity of SOD-1, and that PGR-bleaching is a simple, fast and cheap method to quantify CO3- release from bSOD-1 and hSOD-1 peroxidase activity.

Systematic study of hydroxyl radical production in white wines as a function of chemical composition.

The chemical oxidation of white wines through the Fenton reaction has been widely studied, wherein the primary species is the hydroxyl radical (OH). This radical possesses high oxidising power and may oxidise the primary components in wines. The Fenton reaction in wines is complex and includes the participation of phenolic compounds, organic acids, and metals. However, there has been no systematic study to date that relates wine composition to OH production in real white wines. In this paper, a multivariate model was generated using the partial least squares (PLS) algorithm, and linear correlations were established between wine composition and OH production. Based on the results, the variables were classified as either pro-oxidants (malic acid, p-coumaric acid, and caffeic acid, % prodelphinidins, procyanidins B1, Mn, Cu, and Zn) or antioxidants (cis-piceid, ellagic acid, gallic acid, proanthocyanins, glucose, and proton concentration). Finally, the pathways by which wine compounds participate in OH production are discussed.

Production of hydroxyl radicals and their relationship with phenolic compounds in white wines.

Exposure of white wine to oxygen can cause detrimental effects, such as loss of sensorial characteristics. New antecedents, to the oxidation of wine, establish the importance of the formation of metallic complexes with compounds with adjacent hydroxyls. These complexes could reduce iron, promoting the formation of radicals through the Fenton reaction. The formation of hydroxyl radical (OH) induced by air was found in all 18 white wines analysed by electronic paramagnetic resonance (EPR) spectroscopy. The variation in the OH production was related to the phenolic composition of the wines. The amount of these radicals was linearly related to 5 phenolic compounds (caffeic acid, protocatechuic acid, p-coumaric acid, gentisic acid and syringic acid). Therefore, in this study, the relationship between certain phenolic compounds and the induction and amplification of the OH production was established and was postulated to be a chemical oxidation pathway to the Fenton reaction.