Impact of Leaf Removal on Phenolics and Antioxidant Activity of Trebbiano Berries ( L.).

Leaf removal is a canopy management practice widely applied in viticulture to enhance the phenol composition and concentration of grapes, which then results in improved wine quality. Many studies were carried out on red berried varieties, but information on white ones is scanty. The aim of the study was to assess the effect of basal leaf defoliation in post fruit set on the phenol composition, ascorbate level and antioxidant activity of Trebbiano grapes.

Peptides Derived from Angiogenin Regulate Cellular Copper Uptake.

The angiogenin protein (ANG) is one of the most potent endogenous angiogenic factors. In this work we characterized by means of potentiometric, spectroscopic and voltammetric techniques, the copper complex species formed with peptide fragments derived from the N-terminal domain of the protein, encompassing the sequence 1-17 and having free amino, Ang1-17, or acetylated N-terminus group, AcAng1-17, so to explore the role of amino group in metal binding and cellular copper uptake. The obtained data show that amino group is the main copper anchoring site for Ang1-17.

Controlled Dissociation of Iron and Cyclopentadienyl from a Diiron Complex with a Bridging C Ligand Triggered by One-Electron Reduction.

The one-electron reduction of a diiron cationic complex revealed unique features: cleavage of the diiron structure occurred despite a multidentate bridging C ligand and was accompanied by the clean dissociation of one η-cyclopentadienyl ring and one iron as isolated units. Thus, the iron(II)-iron(II) μ-vinyliminium complex [FeCp(CO)(μ-CO){μ-η:η-C(Et)CHCN(Me)(Xyl)}][SOCF] ([1a]SOCF) reacted with cobaltocene in tetrahydrofuran (THF), affording the iron(II) vinylaminoalkylidene [FeCp(CO){CN(Me)(Xyl)CHC(Et)C(═O)}] (2a) in 77% yield relative to the C ligand. Analogously, [FeCp(CO){CN(Me)(Xyl)CHC(CHOH)C(═O)}] (2b) was obtained in 64% yield from the appropriate diiron precursor and CoCp.

Stable coordination complexes of α-diimines with Nb(v) and Ta(v) halides.

Uncommon examples of coordination compounds of high valent transition metals with α-diimines were obtained and characterized by IR and NMR spectroscopy, X-ray diffraction and/or DFT analysis. The 1 : 1 molar reactions of NbF with a selection of α-diimines afforded the ionic compounds [NbF(DAD)][NbF] (DAD = DAD, 1a; DAD, 1b; DAD, 1c) in 80-90% yields. The addition of DAD to NbOCl gave NbOCl(DAD), 7 (62% yield).

One pot conversion of benzophenone imine into the relevant 2-aza-allenium.

Interaction of common imines with WCl in organic solvents revealed very unusual features in the context of imine chemistry. PhC[double bond, length as m-dash]NH was converted in one pot into the 2-aza-allenium species [PhC[double bond, length as m-dash]N[double bond, length as m-dash]CPh]via N release, with [PhC[double bond, length as m-dash]NH] being a co-product. PhCH[double bond, length as m-dash]NBu underwent C-H bond activation resulting in the formation of [C[triple bond, length as m-dash]N] containing derivatives, together with [PhCH[double bond, length as m-dash]NHBu].

Coordination Compounds of Niobium(IV) Oxide Dihalides Including the Synthesis and the Crystallographic Characterization of NHC Complexes.

The 1:1 molar reactions of NbOX3 with SnBu3H, in toluene at 0 °C in the presence of oxygen/nitrogen donors, resulted in the formation of NbOX2L2 (X = Cl, L2 = dme, 2a; X = Br, L2 = dme, 2b; X = Cl, L = thf, 2c; X = Cl, L = NCMe, 2d; dme = 1,2-dimethoxyethane, thf = tetrahydrofuran), in good yields. The 1:2 reactions of freshly prepared 2d and 2b with the bulky NHC ligands 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, Imes, and 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene, Ixyl, respectively, afforded the complexes NbOCl2(Imes)2, 3, and NbOBr2(Ixyl)2, 4, in 50-60% yields. The reactions of 2b with NaOR, in tetrahydrofuran, gave NbOCl(OR) (R = Ph, 5; R = Me, 6) in about 60% yields.

Copper(II) complexes with peptides based on the second cell binding site of fibronectin: metal coordination and ligand exchange kinetics.

Copper(ii) complexes with short peptides based on the second cell binding site of fibronectin, PHSFN and PHSEN, have been characterized by potentiometric, UV-vis, CD, EPR and NMR spectroscopic methods. The histidine imidazole nitrogen is the anchoring site for the metal ion binding. Thermodynamic and spectroscopic evidence is given that the side chain oxygen donor atom of glutamyl residue in Ac-PHSEN-NH2 is also involved in the binding up to physiological pH.

Phenolic composition and related antioxidant properties in differently colored lettuces: a study by electron paramagnetic resonance (EPR) kinetics.

Differently colored lettuce (Lactuca sativa L.) cultivars (green, green/red, and red) were studied to correlate their phenolic composition with their antioxidant kinetic behavior. Electron paramagnetic resonance (EPR) was employed to monitor decay kinetics of 1,1-diphenyl-2-picrylhydrazyl (DPPH(•)), which allowed the identification of three differently paced antioxidants.

Characterization of an amylose-graft-poly(n-butyl methacrylate) copolymer obtained by click chemistry by EPR and SS-NMR spectroscopies.

We present an investigation of the main chemical and physico-chemical properties of a graft copolymer of amylose and poly(n-butyl methacrylate), Am-g-PBMA, amphiphilic and able to self-assemble in water, prepared by coupling end azide-functionalized PBMA and alkyne-functionalized amylose under convenient click conditions. A deep knowledge of these properties is necessary in the perspective of real applications of the copolymer. To this aim we combined a basic characterization through FT-IR, TGA, ICP-OES and SEM with an extensive EPR and Solid State NMR investigation.

The redox chemistry of [Co6C(CO)15](2-): a synthetic route to new co-carbide carbonyl clusters.

The oxidation and reduction reactions of [Co6C(CO)15](2-) have been studied in detail, leading to the isolation of several new Co-carbide carbonyl clusters. Thus, [Co6C(CO)15](2-) reacts in tetrahydrofuran (THF) with oxidants such as HBF4·Et2O and [Cp2Fe][PF6], resulting first in the formation of the previously reported [Co6C(CO)14](-); then, in CH2Cl2, the new dicarbide [Co11C2(CO)23](2-) is formed. The latter may be further oxidized, yielding the isostructural monoanion [Co11C2(CO)23](-), whereas its reduction with (cyclopentadienyl)2Co affords the unstable trianion [Co11C2(CO)23](3-), which decomposes during workup.

Effects of azole treatments on the physical properties of Candida albicans plasma membrane: a spin probe EPR study.

EPR spectroscopy was applied to investigate the effects of the treatment of Candida albicans cells with fluconazole (FLC) and two newly synthesized azoles (CPA18 and CPA109), in a concentration not altering yeast morphology, on the lipid organization and dynamics of the plasma membrane. Measurements were performed in the temperature range between 0°C and 40°C using 5-doxyl- (5-DSA) and 16-doxyl- (16-DSA) stearic acids as spin probes. 5-DSA spectra were typical of lipids in a highly ordered environment, whereas 16-DSA spectra consisted of two comparable components, one corresponding to a fluid bulk lipid domain in the membrane and the other to highly ordered and motionally restricted lipids interacting with integral membrane proteins.

Interaction of azole compounds with DOPC and DOPC/ergosterol bilayers by spin probe EPR spectroscopy: implications for antifungal activity.

The influence of two antifungal azoles, the newly synthesized compound CPA18 and the commercial drug fluconazole (FLC), on the physical state of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and DOPC/ergosterol bilayers was investigated by spin probe electron paramagnetic resonance (EPR) spectroscopy with the aim of ascertaining if direct interactions with the plasma membrane are implied in the mechanism of action against Candida albicans . 5- and 16-Doxyl-stearic acids (5-DSA and 16-DSA, respectively) were employed to this purpose, and EPR spectra were acquired in the 0 to 40 °C temperature range. Spectral line shapes were analyzed within the theory for slow motion EPR using a microscopically ordered macroscopically disordered model to describe the DOPC multilamellar vesicles and an axially symmetric Brownian model for the spin probe motion.

Long-lived radical cation salts obtained by interaction of monocyclic arenes with niobium and tantalum pentahalides at room temperature: EPR and DFT studies.

The 1:3 reactions of the alkoxy arenes 1,4-(MeO)2 C6 H4 and 1,4-F2 -2,5-(MeO)2 C6 H2 with TaF5 in chloroform at 40-50 °C resulted in formation in about 35 % yield of the long-lived radical cation salts [1,4-(MeO)2 C6 H4 ][Ta2 F11 ] (2 a) and [1,4-F2 -2,5-(MeO)2 C6 H2 ][Ta2 F11 ] (2 b), respectively. The non-alkoxy-substituted [arene][M2 X11 ] [M=Ta, X=F: arene=C6 H5 Me (2 c), 1,4-C6 H4 Me2 (2 d), C6 H5 F (2 e), C6 H5 NO2 (2 f); M=Nb, X=F: arene=C6 H5 Me (4 a), 1,4-C6 H4 Me2 (4 b), C6 H5 F (4 c), C6 H5 NO2 (4 d); M=Ta, X=Cl: arene=1,4-C6 H4 Me2 (5)] were obtained from the 3:1 reactions of MX5 with the appropriate arene in chloroform at temperatures in the range 40-90 °C. Compounds 2-5 were detected by EPR spectroscopy (in CHCl3 ) at room temperature, and their gas-phase structures were optimized by DFT calculations.

Ring opening polymerization of rac-lactide by group 4 tetracarbamato complexes: activation, propagation and role of the metal.

A series of group 4 metal tetracarbamates M(O(2)CNR(2))(4) (M = Ti, R = Et, 1a; M = Zr, R = Et, 1b; (i)Pr, 1c; M = Hf, R = Et, 1d; R = (i)Pr, 1e) were studied as catalytic precursors in the solution polymerization of rac-lactide. The titanium complex but not the zirconium and hafnium ones increase the activity by addition of (i)PrOH. The structure of the carbamato ligand markedly influences the molar mass of polymer; the complexes with isopropyl carbamato ligands produced PLA with molar masses up to 94,000 g mol(-1).

Coordination environment of highly concentrated solutions of Cu(II) in ionic liquids through a multidisciplinary approach.

The coordination environment around Cu(II) in highly concentrated solutions of copper(II) salts (CuCl(2) and Cu(Tf(2)N)(2)) in two pure ionic liquids bearing the same anion, namely, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf(2)N]) and 1-butyl-3-methylimidazolium chloride ([bmim]Cl), is investigated by X-ray photoelectron spectroscopy (XPS), UV/Vis spectroscopy, EPR spectroscopy and DFT calculations. Moreover, the electrochemical behavior of these mixtures is studied. Whereas reversible reduction of Cu(II) to copper metal can be observed in the 1:1 [bmim][Tf(2)N]:Cu(Tf(2)N)(2) solution, 2:1 and 1:1 [bmim]Cl:CuCl(2) mixtures showed one-electron reduction of Cu(II) to Cu(I) with formation of a permanent deposit of CuCl.

Contribution of major lipophilic antioxidants to the antioxidant activity of basil extracts: an EPR study.

Background: The present research analyses the contribution of some lipid antioxidants to the antioxidant activity of lipophilic extracts from basil by an electron paramagnetic resonance (EPR) study using the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). DPPH assay is considered an easy and accurate method with regard to measuring the antioxidant activity of plant extracts and EPR has already been employed to determine antioxidant activities of lipophilic plant extracts.

Results: Lipid extracts were obtained from basil grown hydroponically for 20 or 35 days from sowing and in soil for 35 days from sowing.

Phytic acid prevents oxidative stress in seeds: evidence from a maize (Zea mays L.) low phytic acid mutant.

A maize mutant defective in the synthesis of phytic acid during seed maturation was used as a tool to study the consequences of the lack of this important reserve substance on seed survival. Data on germinability, free iron level, free radical relative abundance, protein carbonylation level, damage to DNA, degree of lipid peroxidation, alpha- and gamma-tocopherol amount and antioxidant capacity were recorded on seeds of maize B73 and of an isogenic low phytic acid mutant (lpa1-241), either unaged or incubated for 7 d in accelerated ageing conditions (46 degrees C and 100% relative humidity). The lpa1-241 mutant, compared to wild type (wt), showed a lower germination capacity, which decreased further after accelerated ageing.

Synthesis of chromium(0) and molybdenum(0) bis (eta(6)-arene) derivatives and their monoelectronic oxidation to [M(eta(6)-arene)(2)](+) cations.

M(eta(6)-arene)(2) species (M = Cr, arene = 1,3,5-Me(3)C(6)H(3); M = Mo, arene = 1,3,5-Me(3)C(6)H(3), 1,3,5-(i)Pr(3)C(6)H(3)), have been prepared by a modified Fischer-Hafner synthesis or by metal vapour techniques. The reaction of Cr(eta(6)-1,3,5-Me(3)C(6)H(3))(2) with the fulvene derivatives pentacarbomethoxycyclopentadiene (pcmcpH), 1-benzoyl-6-hydroxy-6-phenylfulvene (dbcpH), or 1-benzoyl-3-nitro-6-hydroxy-6-phenylfulvene (dbncpH) proceeds with evolution of dihydrogen and formation of the ionic derivatives [Cr(eta(6)-1,3,5-Me(3)C(6)H(3))(2)][E], where E = pcmcp, dbcp, or dbncp. Mo(eta(6)-arene)(2) derivatives (arene = toluene, 1,3,5-Me(3)C(6)H(3), 1,3,5-(i)Pr(3)C(6)H(3)) are oxidized to [Mo(eta(6)-arene)(2)](+) by pcmcpH.

Direct fluorometric determination of fluorescent substances in powders: the case of riboflavin in cereal flours.

Front-face emission spectra of powders can be recorded with a commercial spectrofluorometer. By combining the emissions of a scatterer powder and of a wheat flour sample, the scattering contribution to the front-face emission spectra of flour is removed, and the fluorescence of the flour is isolated. The fluorescence depends on the concentration of the fluorophores.

Effects of gamma-irradiation on the free radical and antioxidant contents in nine aromatic herbs and spices.

Nine spice and aromatic herb samples (i.e., basil, bird pepper, black pepper, cinnamon, nutmeg, oregano, parsley, rosemary, and sage) were gamma-irradiated at a dose of 10 kGy according to commercial practices.

An EPR study on wastewater disinfection by peracetic acid, hydrogen peroxide and UV irradiation.

EPR spectroscopy was applied to obtain qualitative and quantitative information on the radicals produced in disinfection processes of wastewater for agricultural reuse. The DEPMPO spin trap was employed to detect hydroxyl and carbon-centered short living radicals in two different peracetic acid solutions and a hydrogen peroxide solution used for water disinfection either in the absence or in the presence of UV-C irradiation. Moreover, three different kinds of water (wastewater, demineralized water, distilled water) were analysed in order to assess the contribution of Fenton reactions to the radical production.

Antioxidants, free radicals, storage proteins, and proteolytic activities in wheat (Triticum durum) seeds during accelerated aging.

Accelerated aging was performed by incubation of wheat seeds at 40 degrees C and 100% relative humidity for 3, 4, 6, 10, and 14 days. The effects of the treatment on seed germinability and on several biochemical characteristics of flour (carotenoids, free radical and protein contents, and proteolytic activity) and gluten (free radical content and flexibility) were evaluated. A decrease of germinability was found during aging, the germination being completely inhibited after 14 days.