22 research outputs found
Revisión de las variables que afectan el rendimiento de la reacción de transesterificación para la producción de etil ésteres de ácidos grasos
Los ácidos grasos presentes en los aceites vegetales se encuentran en forma de triglicéridos. Laestructura de esta molécula se ve modificada cuando se somete a una reacción detransesterificación (TE).Se han utilizado diferentes aceites vegetales para la reacción de transesterificación en la cual seevaluaron diferentes variables, principalmente tipo de catalizador, relación másicacatalizador/aceite y tiempo de reacción. Se pretende determinar el perfil de ácidos grasos quecomponen dichos aceites, siendo de mayor interés los poliinsaturados de cadenas de 18 átomosde carbono (C18): omega 9, 6 y 3. El perfil de ácidos grasos fue determinado mediante la técnicaGC/FID, y la observación cualitativa del avance de la reacción a través de cromatografía de capafina (TLC).La transesterificación es crucial para el desarrollo tecnológico de un proceso que consiste en laobtención de etil ésteres de ácidos grasos (EEAG) a partir de aceites vegetales comestibles noconvencionales, en el marco de un convenio establecido entre la Facultad Regional Villa María dela UTN y la empresa Porta Hermanos S.A. de la ciudad de Córdoba.En términos generales se indica que se ha estudiado la influencia de las distintas variables yconcluido que la concentración de catalizador tiene relación directa en el avance de la reacción.Fil: Vottero, Tomás J. Universidad Tecnológica Nacional. Facultad Regional Villa María. GISIQ; Argentina.Fil: Stroppiano, María F. Universidad Tecnológica Nacional. Facultad Regional Villa María. GISIQ; Argentina.Fil: Magnani, Ezequiel. Universidad Tecnológica Nacional. Facultad Regional Villa María. GISIQ; Argentina.Fil: Toselli, Luis A. Universidad Tecnológica Nacional. Facultad Regional Villa María. GISIQ; Argentina.Fil: Beltrán, Romina. Universidad Tecnológica Nacional. Facultad Regional Villa María. GISIQ; Argentina.Peer Reviewe
Influence of the Ligand Alkyl Chain Length on the Solubility, Aqueous Speciation, and Kinetics of Substitution Reactions of Water- Soluble M3S4 (M = Mo, W) Clusters Bearing Hydroxyalkyl Diphosphines
Water-soluble [M3S4X3(dhbupe)3]+ diphosphino complexes (dhbupe = 1,2-bis(bis(hydroxybutyl)phosphino)ethane), 1+ (M = Mo, X = Cl) and 2+ (M = W; X = Br), have been synthesized by extending the procedure used for the preparation of their hydroxypropyl analogues by reaction of the M3S4(PPh3)3X4(solvent)x molecular clusters with the corresponding 1,2-bis- (bishydroxyalkyl)diphosphine. The solid state structure of the [M3S4X3(dhbupe)3]+ cation possesses a C3 symmetry with a cuboidal M3S4 unit, and the outer positions are occupied by one halogen and two phosphorus atoms of the diphosphine ligand. At a basic pH, the halide ligands are substituted by hydroxo groups to afford the corresponding [Mo3S4(OH)3(dhbupe)3]+ (1OH +) and [W3S4(OH)3(dhbupe)3]+ (2OH +) complexes. This behavior is similar to that found in 1,2-bis(bis(hydroxymethyl)phosphino)ethane (dhmpe) complexes and differs from that observed for 1,2-bis(bis(hydroxypropyl)phosphino)ethane (dhprpe) derivatives. In the latter case, an alkylhydroxo group of the functionalized diphosphine replaces the chlorine ligands to afford Mo3S4 complexes in which the deprotonated dhprpe acts in a tridentate fashion. Detailed studies based on stopped-flow, 31P{1H} NMR, and electrospray ionization mass spectrometry techniques have been carried out in order to understand the solution behavior and kinetics of interconversion between the different species formed in solution: 1 and 1OH + or 2 and 2OH
+. On the basis of the kinetic results, a mechanism with two parallel reaction pathways involving water and OH− attacks is proposed for the formal substitution of halides by hydroxo ligands. On the other hand, reaction of the hydroxo clusters with HX acids occurs with protonation of the OH− ligands followed by substitution of coordinated water by X−
Synthesis and Structure of Trinuclear W3S4 Clusters Bearing Aminophosphine Ligands and Their Reactivity toward Halides and Pseudohalides
The aminophosphine ligand (2-aminoethyl)- diphenylphosphine (edpp) has been coordinated to the W3(μ-
S)(μ-S)3 cluster unit to afford trimetallic complex [W3S4Br3(edpp)3]+ (1+) in a one-step synthesis process with high yields. Related [W3S4X3(edpp)3]+ clusters (X = F−, Cl−, NCS−; 2+−4+) have been isolated by treating 1+ with the
corresponding halide or pseudohalide salt. The structure of complexes 1+ to 4+ contains an incomplete W3S4 cubane-type cluster unit, and only one of the possible isomers is formed: the one with the phosphorus atoms trans to the capping sulfur and the amino groups trans to the bridging sulphurs. The remaining coordination position on each metal is occupied by X. Detailed studies using stopped-flow, 31P{1H} NMR, and ESI-MS have been carried out in order to understand the solution behavior and the kinetics of interconversion among species 1+, 2+, 3+, and 4+ in solution. Density functional theory (DFT) calculations have been also carried out on the reactions of cluster 1+ with the different anions. The whole set of experimental and theoretical data indicate that the actual mechanism of substitutions in these clusters is strongly dependent on the nature of the leaving and entering anions. The interaction between an entering F− and the amino group coordinated to the adjacent metal have also been found to be especially relevant to the kinetics of these reactions
Inhibition of Gastric Lipase as a Mechanism for Body Weight and Plasma Lipids Reduction in Zucker Rats Fed a Rosemary Extract Rich in Carnosic Acid
BACKGROUND: Rosemary (Rosmarinus officinalis L.) extracts (REs) exhibit hepatoprotective, anti-obesity and anti-inflammatory properties and are widely used in the food industry. REs are rich in carnosic acid (CA) and carnosol which may be responsible for some of the biological activities of REs. The aim of this study was to investigate whether inhibition of lipase activity in the gut may be a mechanism by which a RE enriched in CA (40%) modulates body weight and lipids levels in a rat model of metabolic disorders and obesity. METHODS AND PRINCIPAL FINDINGS: RE was administered for 64 days to lean (fa/+) and obese (fa/fa) female Zucker rats and body weight, food intake, feces weight and blood biochemical parameters were monitored throughout the study. Lipase activity (hydrolysis of p-nitrophenylbutyrate) was measured in the gastrointestinal tract at the end of the study and the contents of CA, carnosol and methyl carnosate were also determined. Sub-chronic administration of RE moderately reduced body weight gain in both lean and obese animals but did not affect food intake. Serum triglycerides, cholesterol and insulin levels were also markedly decreased in the lean animals supplemented with RE. Importantly, lipase activity was significantly inhibited in the stomach of the RE-supplemented animals where the highest content of intact CA and carnosol was detected. CONCLUSIONS: Our results confirm that long-term administration of RE enriched in CA moderates weight gain and improves the plasma lipids profile, primarily in the lean animals. Our data also suggest that these effects may be caused, at least in part, by a significant inhibition of gastric lipase and subsequent reduction in fat absorption
Water-Soluble Mo3S4 Clusters Bearing Hydroxypropyl Diphosphine Ligands: Synthesis, Crystal Structure, Aqueous Speciation, and Kinetics of Substitution Reactions
The [Mo3S4Cl3(dhprpe)3]+ (1+) cluster cation has been prepared by reaction between Mo3S4Cl4(PPh3)3 (solvent)2 and the watersoluble 1,2-bis(bis(hydroxypropyl)phosphino)ethane (dhprpe, L) ligand. The crystal structure of [1]2[Mo6Cl14] has been determined by X-ray diffraction methods and shows the typical incomplete cuboidal structure
with a capping and three bridging sulfides. The octahedral coordination around each metal center is completed with a chlorine and two phosphorus atoms of the diphosphine ligand. Depending on the pH, the hydroxo group of the functionalized diphosphine can substitute the chloride ligands and coordinate to the cluster core to give new clusters with tridentate deprotonated dhprpe ligands of formula [Mo3S4(dhprpe-H)3]+ (2+). A detailed study based on stopped-flow, 31P{1H} NMR, and electrospray ionization mass spectrometry techniques has been carried out to understand the behavior of acid−base equilibria and the kinetics of interconversion between the 1+ and the 2+ forms. Both conversion of 1+ to 2+ and its reverse process occur in a single kinetic step, so that reactions proceed at the three metal centers with statistically controlled kinetics. The values of the rate constants under different conditions are used to discuss on the mechanisms of opening and closing of the chelate rings with coordination or dissociation of chloride
Metabolic engineering to simultaneously activate anthocyanin and proanthocyanidin biosynthetic pathways in Nicotiana spp
[EN] Proanthocyanidins (PAs), or condensed tannins, are powerful antioxidants that remove harmful free oxygen radicals from cells. To engineer the anthocyanin and proanthocyanidin biosynthetic pathways to de novo produce PAs in two Nicotiana species, we incorporated four transgenes to the plant chassis. We opted to perform a simultaneous transformation of the genes linked in a multigenic construct rather than classical breeding or retransformation approaches. We generated a GoldenBraid 2.0 multigenic construct containing two Antirrhinum majus transcription factors (AmRosea1 and AmDelila) to upregulate the anthocyanin pathway in combination with two Medicago truncatula genes (MtLAR and MtANR) to produce the enzymes that will derivate the biosynthetic pathway to PAs production. Transient and stable transformation of Nicotiana benthamiana and Nicotiana tabacum with the multigenic construct were respectively performed. Transient expression experiments in N. benthamiana showed the activation of the anthocyanin pathway producing a purple color in the agroinfiltrated leaves and also the effective production of 208.5 nmol (-) catechin/g FW and 228.5 nmol (-) epicatechin/g FW measured by the p-dimethylaminocinnamaldehyde (DMACA) method. The integration capacity of the four transgenes, their respective expression levels and their heritability in the second generation were analyzed in stably transformed N. tabacum plants. DMACA and phoroglucinolysis/HPLC-MS analyses corroborated the activation of both pathways and the effective production of PAs in T0 and T1 transgenic tobacco plants up to a maximum of 3.48 mg/g DW. The possible biotechnological applications of the GB2.0 multigenic approach in forage legumes to produce "bloatsafe" plants and to improve the efficiency of conversion of plant protein into animal protein (ruminal protein bypass) are discussed.This work was supported by grants BIO2012-39849-C02-01 and BIO2016-75485-R from the Spanish Ministry of Economy and Competitiveness (MINECO) (http://www.idi.mineco.gob.es/portal/site/MICINN) to LAC and a fellowship of the JAE-CSIC program to SF. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Fresquet-Corrales, S.; Roque Mesa, EM.; Sarrión-Perdigones, A.; Rochina, M.; López-Gresa, MP.; Díaz-Mula, HM.; Belles Albert, JM.... (2017). Metabolic engineering to simultaneously activate anthocyanin and proanthocyanidin biosynthetic pathways in Nicotiana spp. PLoS ONE. 12(9). https://doi.org/10.1371/journal.pone.0184839Se018483912
Complete genome sequence of the new urolithin-producing bacterium Gordonibacter urolithinfaciens DSM 27213T.
Peer reviewe