Time filter

Source Type

Diaz-De-Cerio E.,University of Granada | Diaz-De-Cerio E.,Functional Food Research and Development Center | Verardo V.,University of Almeria | Verardo V.,Research Center for Agricultural and Food Biotechnology | And 6 more authors.
Journal of Chemistry | Year: 2015

Literature lacks publications about polar compounds content in infusion or guava leaves tea. Because of that, a comparison between different times of infusion and a conventional ultrasound aqueous extract was carried out. Several polar compounds have been identified by HPLC-ESI-MS and their antioxidant activity was evaluated by FRAP and ABTS assays. Four different classes of phenolic compounds (gallic and ellagic acid derivatives, flavonols, flavanones, and flavan-3-ols) and some benzophenones were determined. The quantification results reported that the order, in terms of concentration of the classes of polar compounds in all samples, was flavonols > flavan-3-ols > gallic and ellagic acid derivatives > benzophenones > flavanones. As expected, the aqueous extract obtained by sonication showed the highest content in the compounds studied. Significative differences were noticed about the different times of infusion and five minutes was the optimal time to obtain the highest content in polar compounds using this culinary method. All the identified compounds, except HHDP isomers and naringenin, were positively correlated with antioxidant activity. © 2015 Elixabet Díaz-de-Cerio et al.

Arrabal-Campos F.M.,University of Almeria | Ona-Burgos P.,University of Almeria | Fernandez I.,University of Almeria | Fernandez I.,Research Center for Agricultural and Food Biotechnology
Polymer Chemistry | Year: 2016

To progress on the practical issues of molecular weight prediction via diffusion NMR, the first log(Dη) vs. log(Mw) calibration curve is provided, allowing the easy and fast determination of weight-average molecular weights with no matter of the solvent used. © 2016 The Royal Society of Chemistry.

Ruiz-Muelle A.B.,University of Almeria | Ona-Burgos P.,University of Almeria | Ortuno M.A.,Autonomous University of Barcelona | Ortuno M.A.,University of Minnesota | And 4 more authors.
Chemistry - A European Journal | Year: 2016

The synthesis and structural characterization of allenyl titanocene(IV) [TiClCp2(CH=C=CH2)] 3 and propargyl titanocene(IV) [TiClCp2(CH2-C≡C-(CH2)4CH3)] 9 have been described for the first time. Advanced NMR methods including diffusion NMR methods (diffusion pulsed field gradient stimulated spin echo (PFG-STE) and DOSY) have been applied and established that these organometallics are monomers in THF solution with hydrodynamic radii (from the Stokes-Einstein equation) of 3.5 and 4.1 Å for 3 and 9, respectively. Full 1H, 13C, Δ1H, and Δ13C NMR data are given, and through the analysis of the Ramsey equation, the first electronic insights into these derivatives are provided. In solution, they are involved in their respective metallotropic allenyl-propargyl equilibria that, after quenching experiments with aromatic and aliphatic aldehydes, ketones, and protonating agents, always give the propargyl products P (when carbonyls are employed), or allenyl products A (when a proton source is added) as the major isomers. In all the cases assayed, the ratio of products suggests that the metallotropic equilibrium should be faster than the reactions of 3 and 9 with electrophiles. Indeed, DFT calculations predict lower Gibbs energy barriers for the metallotropic equilibrium, thus confirming dynamic kinetic resolution. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Alvarez J.M.,National University of Colombia | Alvarez J.M.,University of Magdalena | Cuca L.E.,National University of Colombia | Carrasco-Pancorbo A.,University of Granada | And 4 more authors.
Biochemical Systematics and Ecology | Year: 2016

The chemical investigation of the ethanolic extract from the leaves of Persea caerulea led to the isolation of flavonoids, coumarins and three steroidal type compounds. Based on ESI-MS, UV, IR, GC-MS and 1H and 13C NMR data analysis, the structures of ten isolated compounds were identified as: quercetin (1), kaempferide-3-O-α-l-rhamnopyranoside (2), kaempferol-3-O-α-l-arabinofuranoside (3), quercetin-3-O-α-l-rhamnopyranoside (4), quercetin-3-O-β-glucoside (5), scopoletin (6), isofraxidin (7) campesterol (8), stigmasterol (9) and β-sitosterol (10). In the current research, the isolated compounds 1-9 are reported for the first time in the species Persea caerulea. © 2016 Elsevier Ltd.

Thielemann D.T.,Karlsruhe Institute of Technology | Wagner A.T.,Karlsruhe Institute of Technology | Lan Y.,Karlsruhe Institute of Technology | Ona-Burgos P.,University of Almeria | And 8 more authors.
Chemistry - A European Journal | Year: 2015

A new family of pentadecanuclear coordination cluster compounds (from now on simply referred to as clusters) [{Ln15(OH)20(PepCO2)10(DBM)10Cl}Cl4] (PepCO2 = 2-[{3-(((tert-butoxycarbonyl)amino)methyl)benzyl}amino]acetate, DBM = dibenzoylmethanide) with Ln = Y and Dy was obtained by using the cell-penetrating peptoid (CPPo) monomer PepCO2H and dibenzoylmethane (DBMH) as supporting ligands. The combination of an inorganic cluster core with an organic cell-penetrating peptoid in the coordination sphere resulted in a core component {Ln15(μ3-OH)20Cl}24+ (Ln = Y, Dy), which consists of five vertex-sharing heterocubane {Ln4(μ3-OH)4}8+ units that assemble to give a pentagonal cyclic structure with one Cl atom located in the middle of the pentagon. The solid-state structures of both clusters were established by single-crystal X-ray crystallography. MS (ESI) experiments suggest that the cluster core is robust and maintained in solution. Pulsed gradient spin echo (PGSE) NMR diffusion measurements were carried out on the diamagnetic yttrium compound and confirmed the stability of the cluster in its dicationic form [{Y15(μ3-OH)20-(PepCO2)10(DBM)10Cl}Cl2]2+. The investigation of both static (dc) and dynamic (ac) magnetic properties in the dysprosium cluster revealed a slow relaxation of magnetization, indicative of single-molecule magnet (SMM) behavior below 8 K. Furthermore, the χT product as a function of temperature for the dysprosium cluster gave evidence that this is a ferromagnetically coupled compound below 11 K. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

Discover hidden collaborations