Development of a dispersive liquid-liquid microextraction coupled with magnetic dispersive microsolid phase extraction for determination of triazines in wastewater samples

Producción CientíficaThe combination of two microextraction techniques (dispersive liquid-liquid microextraction [DLLME] and magnetic dispersivemicrosolid phase extraction [MDMSPE]) was developed and reported for atrazine and simazine preconcentration from wastewatersamples. The proposal methodology involved the use of magnetite supports functionalized with different alkyl or phenyl groups. Themagnetic adsorbents were synthesized by the solvothermal methodassisted by microwave, characterized, and used in the samplepreconcentration of atrazine and simazine. The method validation included parameters such as the wastewater matrix effect, repeat-ability, and recovery. The analyte separation and quantification were performed by high-performance liquid chromatography withultraviolet detection (HPLC-DAD). Parameters, such as the polarity and mass of magnetic solids and pH, were evaluated to providebetter extraction performance. The highest recoveries (> 95%) were obtained with 50 mg of the phenyl group support (CS2) at pH 5,using 5 mL of the sample and carbon tetrachloride and methanol, as extraction and dispersive solvents, respectively. The lowest limitsof detection (LOD) achieved were 13.16 and 13.86 ng L−1, and the limits of quantification (LOQ) were 43.89 and 46.19 ng L−1forsimazine and atrazine, respectively, with repeatability (expressed as %RSD) below 5% in all cases. The developed method is simple,easy, and low cost for the analysis of two herbicides potentially dangerous for environmental and human health

An In Silico Approach to Enzymatic Synthesis of Fucooligosaccharides Using α-L-Fucosidase from Thermotoga maritima

Abstract: Fucooligosaccharides comprise the primary group of human milk oligosaccharides. Due to their beneficial properties, a series of synthetic methods have been proposed to obtain them. Enzy- matic methods show great promise, and α-L-fucosidase from Thermotoga maritima has emerged as a powerful catalyst for their production. Nonetheless, the enzyme’s limited substrate scope has de- layed its wider application. The present work aims to compare the relative reactivity of fucose, pNP-fucose, and ethyl-fucose, while also exploring the molecular interactions of these fucosyl-donors with the enzyme through a combination DFT and docking analysis. The HOMO-LUMO band gaps range from −7.14571 to −4.24429 eV, with α/β-pNP-fucose and α-fucose being the three most reactive compounds. Moderate association energies between −6.4 to −5.5 kcal·mol−1 were found in the dock- ing analysis, with α-pNP-fucose and both anomers of ethyl-fucose demonstrating the poorest affinity. In the case of α/β-lactose affinity to the β-fucose/enzyme complex, no significant differ- ences were shown. We conclude that the best fucosyl-donors for transfucosylation are those that maintain an enzyme affinity and reactivity similar to pNP-fucose

Desarrollo de una metodología voltamperométrica para la determinación de Aflatoxina B1 usando un electrodo de carbón vítreo modificado con una película de bismuto y nanopartículas de oro

La Aflatoxina B1 es una micotoxina altamente cancerígena que se encuentra en una gran variedad de alimentos y piensos, por lo tanto, su cuantificación es importante para la industria de los alimentos. En este trabajo de investigación se describe el desarrollo de una metodología electroanalítica utilizando un electrodo de carbón vítreo modificado superficialmente con una película de bismuto y nanopartículas de oro para la cuantificación de Aflatoxina B1, por las ventajas que presenta frente a otras metodologías que ya se han estudiado y validado para la cuantificación de esta sustancia. Los límites de detección y de cuantificación que se obtuvieron después de la de la optimización de la Voltamperometría de Onda Cuadrada mediante un diseño Box-Behnken fueron 11.19 y 37.31 ng L-¹, respectivamente. Estos parámetros nos indican que es posible cuantificar la aflatoxina B1 en un intervalo de concentraciones a nivel traza, tal como se encuentra en alimentos.feeds, therefore, its quantification is important for the food industry. This research paper describes the development of an electroanalytical methodology using a glassy carbon electrode modified with a bismuth film and gold nanoparticles for quantification of Aflatoxin B1, due to the advantages it presents over other methodologies that have already been studied and validated for the quantification of this substance. The detection and quantification limits obtained after optimization of Square Wave Voltammetry using a Box-Behnken design were 11.19 and 37.31 ng L-¹, respectively. These parameters indicated that it is possible to quantify the Aflatoxin B1 in a wide concentration range at trace levels, as expected in food

Caracterización química de aguas subterráneas en pozos y un distribuidor de agua de Zimapán, Estado de Hidalgo, México

The characterization of the ground waters that supply the general distributor of water of Zimapán city, State of Hidalgo, Mexico and the distributor itself, is carried out in this work. Eleven sampling points have been selected in which 28 physical-chemical parameters of the collected water have been determined during 10 samplings distributed along one year (March of 1999-March of 2000). In general these waters present normal physicalchemical properties and are classified as bicarbonated-calcic and bicarbonated-mixed waters, with low levels  of sulfates, chlorides, sodium and potassium; with very high concentrations of As up to 550 ? g· l-1, exceeding in more than 10 times the norm NOM-127-SSA1-1994 for drinking water (Secretaria de Salud, 1996). The study of temporal variation showed significant seasonal variations with an increase in the concentrations of the total elements during the months of February and March (season of scarce rains) and a decrease in the months of April to July (season of rains), this is probably due to dilution effects caused by pluvial precipitation, which is infiltrated to the phreatic mantle. In addition, the supply wells and the points of sampling of the general distributor were correlated by means of a multi-varied analysis of physical-chemical properties.En este trabajo se llevó a cabo la caracterización de las aguas subterráneas que abastecen al distribuidor general de agua de la ciudad de Zimapán Hidalgo, México y del propio distribuidor. Para ello se seleccionaron 11 puntos de muestreo en los que se determinaron 28 parámetros fisico-químicos de las aguas colectadas durante 10 muestreos distribuidos a lo largo de un año (marzo de 1999-marzo de 2000). De forma general, estas aguas presentaron propiedades fisicoquímicas normales clasificadas como aguas bicarbonatadas-cálcicas y bicarbonatadas-mixtas con bajos niveles de sulfatos, cloruros, sodio y potasio; pero presentaron concentraciones de As muy elevadas de hasta 550 ? g· l-1, superando en más de 10 veces la norma NOM-127-SSA1-1994 para aguas potables (Secretaria de Salud, 1996). En el estudio de variación temporal se observaron cambios significativos de carácter estacional con incremento en las concentraciones de los elementos totales durante los meses de febrero y marzo (temporada de escasas lluvias) y una disminución de los mismos durante el período abril a julio (temporadas de lluvias), ésto último probablemente debido a efectos de la dilución causada por la precipitación pluvial que se infiltra al manto freático, además, se han correlacionado los pozos de suministro y los puntos de muestreo del distribuidor general mediante un análisis multivariado de las propiedades fisicoquímicas

Peptide separation of commercial fermented milk during refrigerated storage

Milk is an important source of bioactive compounds. Many of these compounds are released during fermentation and refrigerated storage. The aim of this study was to determine the release of peptides by lactic acid bacteria in commercial fermented milk during refrigerated storage. The size and profile of peptides were analyzed by polyacrylamide gel electrophoresis and sizeexclusion HPLC. During electrophoresis, it was observed that the peptides were released from caseins, whereas β-lactoglobulin was the whey protein with the highest degradation. HPLC analysis confirmed the pattern of peptide formation observed in electrophoresis. Two fractions lower than 2 kDa with aromatic amino acids in their structure were separated. These results were consistent with those reported for structures of peptides with antihypertensive activity. Therefore, the presence of aromatic amino acids in the peptide fractions obtained increases the likelihood of finding peptides with such activity in refrigerated commercial fermented milk. In conclusion, during cold storage, peptides with different molecular weights are released and accumulated. This could be due to the action of proteinases and peptidases of the proteolytic system in lactic acid bacteria

Cereals as a Source of Bioactive Compounds with Anti-Hypertensive Activity and Their Intake in Times of COVID-19

Cereals have phytochemical compounds that can diminish the incidence of chronic diseases such as hypertension. The angiotensin-converting enzyme 2 (ACE2) participates in the modulation of blood pressure and is the principal receptor of the virus SARS-CoV-2. The inhibitors of the angiotensin-converting enzyme (ACE) and the block receptors of angiotensin II regulate the expression of ACE2; thus, they could be useful in the treatment of patients infected with SARS-CoV-2. The inferior peptides from 1 to 3 kDa and the hydrophobic amino acids are the best candidates to inhibit ACE, and these compounds are present in rice, corn, wheat, oats, sorghum, and barley. In addition, the vitamins C and E, phenolic acids, and flavonoids present in cereals show a reduction in the oxidative stress involved in the pathogenesis of hypertension. The influence of ACE on hypertension and COVID-19 has turned into a primary point of control and treatment from the nutritional perspective. The objective of this work was to describe the inhibitory effect of the angiotensin-converting enzyme that the bioactive compounds present in cereals possess in order to lower blood pressure and how their consumption could be associated with reducing the virulence of COVID-19

Bioactive compounds in aqueous extracts of lemon balm (Melissa officinalis) cultivated in Mexico

Lemon balm (Melissa officinalis) is a plant in the family of Lamiaceae. In Mexican traditional medicine it is used to alleviate gastrointestinal and hepatic problems. Studies carried out mainly in ethanolic and methanolic extracts, have revealed the presence of diverse compounds to which those medicinal properties are attributed. The objective of this research work was to extract in aqueous solution the antioxidants present in lemon balm and identify them through HPLC-MS. A Box-Behnken design was applied to determine the physical conditions of antioxidant extraction, where the analyzed variables were time, temperature and sample quantity. The antioxidant activity was determined through methodologies of DPPH*, FRAP and total phenolics. The aqueous solution with the highest antioxidant activity was analyzed through HPLC-MS. The results showed that the interaction temperature-time has a positive influence on the liberation of antioxidants. The best condition for a conventional extraction of antioxidants was 90°C, 15 min and 2 g of sample. Higher correlations were observed at r2>0.6 between determined antioxidant activity by DPPH* (or FRAP) vs Total phenolics; this would indicate that such activity could be attributed to phenolic compounds whose presence was confirmed through an analysis by HPLC-MS.El toronjil (Melissa officinalis) es una planta de la familia Lamiaceae. En la medicina tradicional mexicana es utilizado para aliviar problemas gastrointestinales y hepáticos. Algunos estudios realizados con extractos etanólicos y metanólicos de dicha planta, han revelado la presencia de diversos compuestos a los que se les atribuye sus propiedades medicinales. El objetivo de esta investigación fue extraer en solución acuosa los antioxidantes presentes en el toronjil e identificarlos a través de HPLC-MS. Para ello, se aplicó un diseño de experimentos Box-Behnken a fin de determinar las condiciones físicas de extracción de antioxidantes; las variables analizadas fueron tiempo, temperatura y cantidad de muestra. La actividad antioxidante fue determinada a través de las metodologías de DPPH*, FRAP y fenoles totales. El extracto acuoso con la mayor actividad antioxidante fue analizado mediante HPLCMS. Los resultados mostraron que la interacción tiempotemperatura tuvo una influencia positiva en la liberación de antioxidantes. La mejor condición para la extracción de antioxidantes presentes en el toronjil fue 90°C, 15 min y 2 g de muestra. Correlaciones superiores a r2>0.6 fueron determinadas entre la actividad antioxidante medida por DPPH* (o FRAP) vs Fenoles totales; esto podría indicar que la actividad antioxidante encontrada podría atribuirse a compuestos de tipo fenólico cuya presencia fue confirmada por el análisis en HPLC-MS

Antithrombotic Activity of Milk Protein Hydrolysates by Lactic Acid Bacteria Isolated from Commercial Fermented Milks

ABSTRACT In the last decade, thrombosis has been one of the pathologies with high incidence creating great concern in Health Institutes all around the world. Considering this, the aim of this research was to determine the antithrombotic activity of peptides released during lactic fermentation. Reconstituted skim milk powder was fermented by Lactobacillus casei Shirota and Lactobacillus johnsonii LA1 isolated from commercial fermented milks. The hydrolysis degree and proteolytic profile were analyzed by trinitrobenzenesulfonic acid spectrophotometry method and by peptide polyacrylamide electrophoresis gel separation. The milk fermented by Lactobacillus casei Shirota exhibited a higher concentration of free amino groups than that fermented by Lactobacillus johnsonii LA1. Additionally, in both fermentation systems peptides with molecular weights lower than 1.4 kDa were observed. The highest inhibition of thrombin (31.67±2.35%) was observed in milk fermented by Lactobacillus johnsonii LA1 at 10 hours of fermentation. Finally, no relationship was found between the antithrombotic capacity and the proteolytic profile

Kinetic parameters of lipid oxidation in third generation (3G) snacks and its influence on shelf-life

Abstract In food systems, lipid oxidation is one of the most important factors affecting food quality, nutrition, safety, color and consumer acceptance. The objective of this study was to determine the kinetic parameters of lipid oxidation and its influence in the shelf life of third generation (3G) snacks stored in three types of packaging (polyethylene, polypropylene + Kraft paper, and polyethylene + polypropylene) at 25 °C and 40 °C. The peroxide value was the quality parameter selected and monitored for a 60 day period using a spectrophotometric technique. Based on the Arrhenius equation and activated complex theory, reaction rate constants (k), activation energies (Ea), Q10 factors, activation enthalpies (∆H‡), and activation entropies (∆S‡ ) for oxidative stability in 3G snacks were calculated. Results showed that oxidation phenomena can occur in the 3G snacks and affect its shelf-life. Packaging C (polyethylene + polypropylene) was the most appropriate for the storage of this kind of product. Finally, the shelf life of the analyzed pellets was longer than one year at 25 °C and it may be extended with the appropriate mix of packaging materials