143 research outputs found

    The structure of the agrochemical fungicidal 4-Chloro-3-(3,5-dichloropheny)-1H-pyrazole, RPA 406194 and related compounds

    Get PDF
    The difficulties to obtain convenient monocrystals of the important fungicide RPA 406194 have been overcome by a combination of solid state 13C NMR, X-ray powder diffraction and molecular modeling. The compound, a 3-aryl tautomer, crystallizes forming infinite chains of molecules bonded by N–H· · ·N hydrogen bonds, leading to needle-shaped crystals. The tautomerism (equilibrium constant and energy barrier) of this compound in solution has been studied

    Optimization of total anthocyanin content and antioxidant activity of a Hibiscus sabdariffa infusion using response surface methodology

    Get PDF
    Hibiscus sabdariffa L. calyces are underutilized sources of health-promoting anthocyanins. Infusions are the most common way to consume them, but because anthocyanins are thermosensitive, prolonged extraction times at high temperatures may reduce their bioactivities, suggesting the need to identify optimal preparation conditions. Response surface methodology was used to establish calyces-to-water ratio (X1: 1–20 g/100 mL), temperature (X2: 70–100 °C), and time (X3: 1–30 min) that would produce an infusion with optimized total anthocyanin content (TAC) and antioxidant activity. Under optimum conditions (X1=10 g/100 mL, X2=88.7 °C, and X3=15.5 min) TAC was 132.7±7.8 mg cyanidin-3-glucoside equivalents (C3G)/100 mL, and antioxidant activity was 800.6±69.9 (DPPH assay), and 1792.0±153.5 (ABTS assay) μmol Trolox equivalents (TE)/100 mL. Predicted and experimental results were statistically similar. Identifying ideal processing conditions can promote consumption of an H. sabdariffa-based functional beverage with high anthocyanin content and antioxidant activity that exert health-promoting bioactivities on the consumer

    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

    Get PDF
    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

    In vitro Inhibition of Pancreatic Lipase by Polyphenols: A Kinetic, Fluorescence Spectroscopy and Molecular Docking Study

    Get PDF
    Svrha je ovog istraživanja bila ispitati molekulsko uklapanje i inhibicijski učinak četiri fenolna spoja pronađena u ljutim papričicama, i to: kavene kiseline, p-kumarne kiseline, kvercetina i kapsaicina, na aktivnost lipaze izolirane iz svinjske gušterače. Najjači inhibicijski učinak imao je kvercetin (IC50=(6.1±2.4) μM), zatim p-kumarna (170.2±20.6) μM) i kavena kiselina (401.5±32.1) μM), dok su kapsaicin i ekstrakt ljute papričice imali iznimno slab učinak. Svi polifenolni spojevi imali su inhibicijski učinak miješanog tipa. Mjerenjem fluorescencije utvrđeno je da su polifenolni spojevi ugasili prirođenu fluorescenciju lipaze izolirane iz gušterače, i to pomoću statičkog mehanizma. Sekvencija Stern-Volmerove konstante bila je: kvercetin, kavena kiselina, te p-kumarna kiselina. Rezultati ispitivanja molekulskih uklapanja pokazali su da se kavena kiselina, kvercetin i p-kumarna kiselina vežu blizu, za razliku od kapsaicina koji se veže daleko od aktivnog mjesta. Vodikove veze i hidrofobne pi-interakcije glavni su načini međusobnog povezivanja polifenolnih spojeva u lipazi izoliranoj iz gušterače.The inhibitory activity and binding characteristics of caffeic acid, p-coumaric acid, quercetin and capsaicin, four phenolic compounds found in hot pepper, against porcine pancreatic lipase activity were studied and compared to hot pepper extract. Quercetin was the strongest inhibitor (IC50=(6.1±2.4) μM), followed by p-coumaric acid ((170.2±20.6) μM) and caffeic acid ((401.5±32.1) μM), while capsaicin and a hot pepper extract had very low inhibitory activity. All polyphenolic compounds showed a mixed-type inhibition. Fluorescence spectroscopy studies showed that polyphenolic compounds had the ability to quench the intrinsic fluorescence of pancreatic lipase by a static mechanism. The sequence of Stern-Volmer constant was quercetin, followed by caffeic and p-coumaric acids. Molecular docking studies showed that caffeic acid, quercetin and p-coumaric acid bound near the active site, while capsaicin bound far away from the active site. Hydrogen bonds and π-stacking hydrophobic interactions are the main pancreatic lipase-polyphenolic compound interactions observed

    Twitter as a Tool for Teaching and Communicating Microbiology: The #microMOOCSEM Initiative

    Get PDF
    Online social networks are increasingly used by the population on a daily basis. They are considered a powerful tool for science communication and their potential as educational tools is emerging. However, their usefulness in academic practice is still a matter of debate. Here, we present the results of our pioneering experience teaching a full Basic Microbiology course via Twitter (#microMOOCSEM), consisting of 28 lessons of 40-45 minutes duration each, at a tweet per minute rate during 10 weeks. Lessons were prepared by 30 different lecturers, covering most basic areas in Microbiology and some monographic topics of general interest (malaria, HIV, tuberculosis, etc.). Data analysis on the impact and acceptance of the course were largely affirmative, promoting a 330% enhancement in the followers and a >350-fold increase of the number of visits per month to the Twitter account of the host institution, the Spanish Society for Microbiology. Almost one third of the course followers were located overseas. Our study indicates that Massive Online Open Courses (MOOC) via Twitter are highly dynamic, interactive, and accessible to great audiences, providing a valuable tool for social learning and communicating science. This strategy attracts the interest of students towards particular topics in the field, efficiently complementing customary academic activities, especially in multidisciplinary areas like Microbiology.Versión del edito

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

    Get PDF
    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
    corecore