Inhibición de la polifenol oxidasa de manzana “red delicious” por compuestos naturales, como una estrategia para reducir el pardeamiento de productos mínimamente procesados de manzana

En los últimos años, ha existido una tendencia creciente a consumir frutos y vegetales frescos cortados. Uno de los principales problemas para la comercialización de este tipo de productos, es el pardeamiento enzimático ocasionado por la actividad de la enzima polifenol oxidasa (PPO, EC 1.14.18.1). Este problema es particularmente importante en la manzana, por su tendencia a oxidarse una vez que es cortada. Debido a que la FDA ha prohibido el uso de sulfitos para reducir el pardeamiento de productos frescos cortados, se han desarrollado diversos estudios para reducir este efecto indeseable. Recientemente Villegas-Ochoa y col. En el 2005 demostraron que el uso de extractos de mieles típicas del estado de Sonora, México, reducían el oscurecimiento de jugos de manzana. En el presente trabajo se estudió el mecanismo de inhibición de la enzima PPO de manzana “Red Delicious” por diversos compuestos de origen natural: extracto de miel de palo fierro (Olneya tesota), ester fenílico del ácido caféico (CAPE) y L-cisteina. Se utilizó ácido clorogénico como sustrato, y la actividad se determinó espectrofotométricamente, midiendo el incremento de absorbancia a 400 y 420 nm. El CAPE, uno de los principales polifenoles presentes en mieles, presentó una inhibición de la PPO, por un mecanismo que puede ser considerado como una coprecipitación de la enzima o del sustrato. Palo Fierro y L-cisteina presentaron una inhibición del tipo mixto. Estos resultados pueden ser explicados, en el caso del Palo Fierro, considerando que el extracto es una mezcla de diferentes compuestos que pueden interactuar con la PPO de diferente manera. Estos resultados concuerdan con los resultados de inhibición del pardeamiento de jugo de manzana por los extractos naturales descritos previamente

The evolution of the ventilatory ratio is a prognostic factor in mechanically ventilated COVID-19 ARDS patients

Background: Mortality due to COVID-19 is high, especially in patients requiring mechanical ventilation. The purpose of the study is to investigate associations between mortality and variables measured during the first three days of mechanical ventilation in patients with COVID-19 intubated at ICU admission. Methods: Multicenter, observational, cohort study includes consecutive patients with COVID-19 admitted to 44 Spanish ICUs between February 25 and July 31, 2020, who required intubation at ICU admission and mechanical ventilation for more than three days. We collected demographic and clinical data prior to admission; information about clinical evolution at days 1 and 3 of mechanical ventilation; and outcomes. Results: Of the 2,095 patients with COVID-19 admitted to the ICU, 1,118 (53.3%) were intubated at day 1 and remained under mechanical ventilation at day three. From days 1 to 3, PaO2/FiO2 increased from 115.6 [80.0-171.2] to 180.0 [135.4-227.9] mmHg and the ventilatory ratio from 1.73 [1.33-2.25] to 1.96 [1.61-2.40]. In-hospital mortality was 38.7%. A higher increase between ICU admission and day 3 in the ventilatory ratio (OR 1.04 [CI 1.01-1.07], p = 0.030) and creatinine levels (OR 1.05 [CI 1.01-1.09], p = 0.005) and a lower increase in platelet counts (OR 0.96 [CI 0.93-1.00], p = 0.037) were independently associated with a higher risk of death. No association between mortality and the PaO2/FiO2 variation was observed (OR 0.99 [CI 0.95 to 1.02], p = 0.47). Conclusions: Higher ventilatory ratio and its increase at day 3 is associated with mortality in patients with COVID-19 receiving mechanical ventilation at ICU admission. No association was found in the PaO2/FiO2 variation

Clustering COVID-19 ARDS patients through the first days of ICU admission. An analysis of the CIBERESUCICOVID Cohort

Background Acute respiratory distress syndrome (ARDS) can be classified into sub-phenotypes according to different inflammatory/clinical status. Prognostic enrichment was achieved by grouping patients into hypoinflammatory or hyperinflammatory sub-phenotypes, even though the time of analysis may change the classification according to treatment response or disease evolution. We aimed to evaluate when patients can be clustered in more than 1 group, and how they may change the clustering of patients using data of baseline or day 3, and the prognosis of patients according to their evolution by changing or not the cluster.Methods Multicenter, observational prospective, and retrospective study of patients admitted due to ARDS related to COVID-19 infection in Spain. Patients were grouped according to a clustering mixed-type data algorithm (k-prototypes) using continuous and categorical readily available variables at baseline and day 3.Results Of 6205 patients, 3743 (60%) were included in the study. According to silhouette analysis, patients were grouped in two clusters. At baseline, 1402 (37%) patients were included in cluster 1 and 2341(63%) in cluster 2. On day 3, 1557(42%) patients were included in cluster 1 and 2086 (57%) in cluster 2. The patients included in cluster 2 were older and more frequently hypertensive and had a higher prevalence of shock, organ dysfunction, inflammatory biomarkers, and worst respiratory indexes at both time points. The 90-day mortality was higher in cluster 2 at both clustering processes (43.8% [n = 1025] versus 27.3% [n = 383] at baseline, and 49% [n = 1023] versus 20.6% [n = 321] on day 3). Four hundred and fifty-eight (33%) patients clustered in the first group were clustered in the second group on day 3. In contrast, 638 (27%) patients clustered in the second group were clustered in the first group on day 3.Conclusions During the first days, patients can be clustered into two groups and the process of clustering patients may change as they continue to evolve. This means that despite a vast majority of patients remaining in the same cluster, a minority reaching 33% of patients analyzed may be re-categorized into different clusters based on their progress. Such changes can significantly impact their prognosis

Identificación de compuestos fenólicos en extractos de almendra (Prunus dulcis) y nuez pecana (Carya illinoinensis) mediante cromatografía líquida acoplada a espectrometría de masas en tándem (HPLC-MS/MS)

Almonds and pecans are considered functional foods because their regular intake provides protection against several chronic-degenerative diseases. Phenolic compounds are some of the most bioactive components of these tree nuts; yet, their identification and characterization is regularly viewed as an analytical challenge. The aim of the present work was to characterize the phenolic compound profile of acetone and methanol extracts of almond and pecan nut, by using HPLC coupled to tandem mass spectrometry (MS/MS). First, high resolution MS (Q-TOF) was used to identify phenolic compounds in the extracts: 29 compounds were detected in almond (22 in acetone extract, 24 in ethanol extract) and 43 in pecan (39 in acetone extract, 37 in ethanol extract). Identity of 6 almond compounds and 20 pecan compounds was confirmed through analysis of their MS/MS fragmentation patterns. Phenolic profiles were different between pecan and almond but similar between extraction solvents for a same tree nut species. Flavonols and flavanones were the major types of phenolic compounds in almond, while pecan phenolics were mostly hydrolysable (ellagitannins acid ellagic acid derivatives) and condensed tannins (upto tetramers). Three ellagitannins are described for the first time in pecan.La almendra y nuez pecana son alimentos funcionales, cuyo consumo habitual puede prevenir el desarrollo de numerosas enfermedades crónico-degenerativas. Los compuestos fenólicos (CF) son algunos de los que poseen mayor actividad biológica en estos frutos secos, pero su identificación y caracterización siempre representa un reto analítico. El objetivo del presente trabajo fue caracterizar el perfil de los CF, mediante HPLC acoplado a espectrometría de masas en tándem (MS/MS) de dos tipos de extractos de nuez pecana y almendra, un extracto etanólico y uno acetónico. Se identificaron, mediante HPLC acoplado a espectrometría de masas de alta resolución (Q-TOF), 29 compuestos en almendra (22 estuvieron en el extracto acetónico y 24 en el etanólico) y 43 en nuez pecana (39 en el acetónico y 37 en el etanólico). La identidad de 6 compuestos de la almendra y 20 de nuez pecana se confirmó mediante el análisis de sus patrones de fragmentación en el modo MS/MS del equipo. El perfil de los CF fue claramente diferente entre almendra y nuez, pero muy parecido entre ambos tipos de solventes empleados (acetona y etanol), para un mismo fruto seco. En la almendra predominó la presencia de flavonoles y flavanonas, mientras que en nuez pecana predominaron taninos hidrolizables (sobre todo elagitaninos y derivados simples del ácido elágico) y condensados (hasta tetrámeros). En este estudio se describe por primera vez la identificación de tres elagitaninos en nuez pecana

Fosfatasa alcalina (E.C.3.1.3.1): bioquímica y aplicaciones en las ciencias biomédicas, ecológicas y alimentarias

Las fosfatasas alcalinas (FAl; E.C.3.1.3.1) son una superfamilia de metaloenzimas homodiméricas que hidrolizan mono esteres orto fosfóricos unidos a nucleótidos, proteínas y muchos otros sustratos, a pH entre 8-11 y en presencia de iones Zn+2 y Mg+2. Se inhiben con Be++, Fe++, Cu++ y varios poli aniones. Varios estudios han confirmado su carácter pleiotrópico, pero nuevos estudios estructurales, cinéticos y genéticos revelan nuevos roles metabólicos y funcionales. La concentración de FAl total y/ o isoenzimas, ha sido explotada como marcador de varios fenómenos biológicos en ciencias biomédicas (e.g. funcionalidad renal, hepática y ósea), ambientales (e.g. fosfatos en suelo marino y su remoción de aguas residuales), zoología (e.g. ciclos de fertilidad en aves) y alimentos (e.g. pasteurización de la leche). Como herramienta analítica, seguirán dando pie al desarrollo de varias técnicas inmuno enzimáticas, para beneficio de las ciencias biológicas. Abstract The alkaline phosphatases (AP) are a superfamily of homodimeric metalloenzymes (E.C.3.1.3.1) that hydrolyze orthophosphoric monoesters linked to nucleotides, proteins and many other substrates, at pH 8-11 and in the presence of Zn+2 and Mg+2 ions. They are inhibited by Be++, Fe++, Cu++ and several anions. Several studies have confirmed their pleiotropic nature, but new structural, kinetic and genetic studies reveal novel metabolic and functional characteristics. Total AP concentration and/or isoenzyme quantification, has been exploited as a marker of several biological phenomenon in biomedical sciences (e.g. renal, hepatic and bone functionality), environmental (e.g. phosphate in the seafloor and its removal from wastewater), zoology (e.g. fertility cycles in birds) and food sciences (e.g. milk pasteurization). As an analytic tool, will give rise to the development in various immune enzymatic techniques for the benefit of the life sciences. Keywords: alkaline phosphatase, enzyme kinetics, biomedicine, environmental sciences, food sciences

Taninos hidrolizables y condensados: naturaleza química, ventajas y desventajas de su consumo

Los taninos hidrolizables y condensados han sido tema de debate en múltiples revisiones nutricionales. Mientras que algunos autores defienden su impacto benéfico en la salud, otros señalan sus acciones anti fisiológicas en el organismo que los consume. Los taninos son compuestos ampliamente distribuidos y consumidos en alimentos de origen vegetal, cuya cantidad, estructura química y actividad biológica están determinadas por múltiples factores, algunos de los cuales se discuten en esta revisión. Por todo esto, los taninos pueden ser percibidos como compuestos polifenólicos cuyo consumo puede traer numerosos impactos benéficos pero cuyos efectos negativos, observados en otros estudios, no deben ser pasados por alto al momento de hacer recomendaciones para su consumo como parte de una dieta habitual. Abstract Hydrolysable and condensed tannins have been subject of debate in multiple nutritional reviews. While some authors advocate their beneficial impact on health, others point out their anti-physiological impact in the organism that consumes them. Tannins are compounds widely distributed and consumed in plant foods; the amount, chemical structure and biological activity are determined by multiple factors, some of which will be discussed in this review. For all these, tannins can be perceived as polyphenolic compounds whose consumption can bring several beneficial impacts; but whose negative effects, observed in others studies, should not be overlooked when making recommendations for consumption as part of a regular diet. Keywords: polyphenols, food, health, proanthocyanidins, gallotannins, ellagitannins

Aspectos estructurales y funcionales de la N-Succinil-L, L-diaminopimelato desuccinilasa, una enzima clave para el crecimiento bacteriano y un blanco para el control antimicrobiano

N-Succinyl-L, L-diaminopimelate desuccinylase (DapE) is a strictly dimeric zinc-dependent amidohydrolase, which catalyzes the decomposition of N-succinyl-L, L-2,6-diaminopimelate (NSDAP), into succinate and diaminopimelate (DAP). This reaction constitutes the only source of meso-diaminopimelate (mDAP) and L-Lys in most bacteria. DapE is essential for bacterial growth and a pharmacological antimicrobial target. The development of anti-DapE inhibitors must take into account the dynamic properties of the enzyme. There is a special interest in compounds that block the formation of the oxyanion hole, where is assembled with groups of both subunits of the dimer and accommodated in its catalytic position by the conformational change of the enzyme from an open to a closed state, upon productive substrate binding. The hole stabilizes reaction intermediaries, thus contributing to the decrease in the activation energy. Based on the crystallographic analysis and the coupling of the substrate into DapE presented in this work, the role of the conformational flexibility of the enzyme in substrate hydrolysis is discussed. It is observed that the susceptible carbonyl group of the substrate and a water molecule located in the active site are near to the trajectory of attack, the Bürgi-Dunitz angle.La N-Succinil-L, L-diaminopimelato desuccinilasa (DapE) es una amidohidrolasa dependiente de iones de zinc, homodimérica estricta, que cataliza la descomposición del N-succinil-L, L-2,6-diaminopimelato (NSDAP), en succinato y diaminopimelato (DAP). Reacción que constituye la única fuente de meso-diaminopimelato (mDAP) y L-Lys en la mayoría de las bacterias. DapE es esencial para el crecimiento bacteriano y un blanco farmacológico antimicrobiano. El desarrollo de los inhibidores anti-DapE debe tener en cuenta las propiedades dinámicas de la enzima. Se buscan compuestos que interfieran con la formación del agujero del oxianión, en donde participan grupos de ambas subunidades del dímero, que se acomoda en posición catalítica mediante el cambio conformacional de la enzima de un estado abierto a uno cerrado, después de la unión del sustrato; estabilizando a los intermediarios de reacción y produciendo un descenso en la energía de activación. Con base en el análisis cristalográfico y el acoplamiento del sustrato en DapE que se presenta en este trabajo, se discute el papel de la flexibilidad conformacional de la enzima en la hidrólisis del sustrato. Se observa que tanto el grupo carbonilo del sustrato es susceptible al ataque como una molécula de agua ubicada en el sitio activo y se encuentran cercanos a la trayectoria de ataque, en el ángulo de Bürgi-Dunitz

Microencapsulation of cinnamon leaf (Cinnamomum zeylanicum) and garlic (Allium sativum) oils in beta-cyclodextrin

Cinnamon leaf (CLO) and garlic oils (GO) are good antimicrobials, however, their volatility complicates their application as food preservatives. Hence, microencapsulation of CLO and GO with beta-cyclodextrin (beta-CD) was studied at 4:96, 8:92, 12:88, and 16:84 (oil:beta-CD) percent weight ratios. Microcapsule characterization included gas chromatography analysis, moisture sorption-desorption isotherms, infrared spectroscopy (IR), and antifungal activity against Alternaria alternata. Major oil constituents were eugenol for CLO and allyl disulfide for GO. The 16:84 ratio (CLO:beta-CD) showed the highest eugenol content; the allyl disulfide content was higher, but not significantly different (P > 0.05) for the 12:88 and 16:84 ratios. Microcapsules showed lower moisture sorption than beta-CD, although during water desorption there were no difference between them. Hydrogen bonds were detected between oil constituents and beta-CD by IR spectroscopy. CLO:beta-CD and GO:beta-CD microcapsules displayed good antifungal activity against Alternaria alternata. Therefore, CLO and GO microcapsules can have important applications in the food industry as stable natural antimicrobial compound system