Effect of a Prolonged-Release System of Urea on Nitrogen Losses and Microbial Population Changes in Two Types of Agricultural Soil.

Urea is the nitrogen-containing fertilizer most used in agricultural fields; however, the nutrient given by the urea is lost into the environment. The aim of this research was to determine the effect of two soil textures by applying a prolonged-release system of urea (PRSU) on the N losses. This research shows an important decrease of the nitrate and ammonium losses from 24.91 to 87.94%. Also, the microbiological population increases after the application of the PRSU. It was concluded that both soil textures presented the same loss-reduction pattern, where the N from the nitrates and ammonium was reduced in the leachates, increasing the quality of the soil and the microbial population in both soil textures after the PRSU application.

Cápsulas de polvo de arándano como propuesta nutracéutica para mejorar la bioaccesibilidad de compuestos fenólicos / Blueberry Powder capsules as a nutraceutical proposal to improve bioaccessibility of phenolic compounds. Introduction

El arándano (Vaccinium corymbosum L.) posee un alto contenido de compuestos fenólicos los cuales han sido estudiados principalmente por su actividad antioxidante, antiobesogénica, antiinflamatoria, entre otras. Objetivo. Evaluar el efecto de la digestión gastrointestinal in vitro sobre la bioaccesibilidad de compuestos fenólicos y actividad antioxidante de una formulación nutracéutica de arándano (cápsula), comparado con arándano fresco y polvo. Materiales y métodos. Se obtuvieron extractos metanólicos de muestras de arándano fresco y liofilizado y se determinó su contenido de fenoles, flavonoides y antocianinas totales, así como también actividad antioxidante. Se llevó a cabo un ensayo de simulación de digestión gastrointestinal para evaluar la bioaccesibilidad de los compuestos fenólicos presentes en las muestras. Resultados. Los resultados mostraron que la digestión gástrica de arándano en polvo y en cápsula promovió una mayor bioaccesibilidad de fenoles (42% y 40%), flavonoides (52% y 33%) y antocianinas (45% y 40%) comparado con digestos de arándano fresco. Posterior a la digestión intestinal, la bioaccesibilidad de fenoles (63%) y flavonoides (67%) fue mayor en la cápsula de arándano comparada con su contraparte arándano en polvo. Las condiciones de digestión intestinal afectaron negativamente la bioaccesibilidad de las antocianinas independientemente del tipo de muestra evaluada. Conclusión. Las condiciones de digestión gástrica promueven una mayor estabilidad de los compuestos fenólicos en arándano en polvo y en cápsula lo que pudiera ser relevante para el mantenimiento de un ambiente antioxidante a este nivel. Las condiciones de digestión intestinal afectaron de manera particular a los compuestos fenólicos de arándano fresco y polvo, pero no a la cápsula, lo que puede sugerir que el encapsulamiento protegió de las condiciones alcalinas a los fenoles presentes. Se sugieren estudios posteriores sobre absorción in vitro de los componentes remanentes en intestino y sus posibles efectos sobre biomarcadores de estrés oxidativo en modelos in vivo(AU)

Blueberry (Vaccinium corymbosum L.) has a high content of phenolic compounds which have been studied mainly for their antioxidant, antiobesogenic, anti-inflammatory activity, among others. Objetive. The objective of the present study was to evaluate the effect of in vitro gastrointestinal digestion on the bioaccessibility of phenolic compounds and antioxidant activity of a nutraceutical formulation of blueberry (capsule), compared to fresh and powder blueberry. Materials and methods. Methanolic extracts of fresh and lyophilized blueberry were obtained and determined its total phenols, flavonoids, anthocyanins content, as well as antioxidant activity. A gastrointestinal digestion simulation test also was carried out to assess the bioaccessibility of the phenolic compounds found in samples. Results. The results showed that gastric digestion of powder and capsule blueberry promoted greater bioaccessibility of phenols (42% and 40%), flavonoids (52% and 33%) and anthocyanins (45% and 40%), compared to fresh blueberry digests. After intestinal digestion, the bioaccessibility of phenols (63%) and flavonoids (67%) was higher in the blueberry capsule compared to its powdered blueberry counterpart. The intestinal digestion conditions negatively affected the bioaccessibility of anthocyanins regardless of the type of sample evaluated. Conclusion. Gastric digestion conditions promote greater stability of phenolic compounds in powdered and capsule blueberries, which could be relevant for the maintenance of an antioxidant environment at this level. The intestinal digestion conditions particularly affected the phenolic compounds of fresh and lyophilized blueberry, but not the capsule, which may suggest that encapsulation protected the phenols present from alkaline conditions. Further studies on in vitro absorption of the remaining components in the intestine and their possible effects on oxidative stress biomarkers in in vivo models are suggested(AU)

Identification of arginine kinase as an allergen of brown crab, Callinectes bellicosus, and in silico analysis of IgE-binding epitopes.

In recent years there has been an increase in the prevalence of allergic reactions to contact with/or consumption of crustaceans by immune responses mediated by IgE antibodies. Arginine kinase (AK) is considered one of the main allergens present in marine invertebrates. Currently, the allergenic potential of the brown crab (Callinectes bellicosus), which is a crustacean of great economic importance, has not been studied. Therefore, the aim of this work was to identify C. bellicosus AK as an allergen and to predict IgE-binding epitopes through immunobioinformatic analysis. AK was purified by precipitation with ammonium sulfate and ion- exchange chromatography. AK allergenicity was evaluated by IgE reactivity against sera from crustacean-allergic and non-allergic patients in both native and denaturing conditions. Additionally, a homology model was built based on the deduced amino acid sequence. A single band (~40 kDa) was found in SDS-PAGE, which was identified as an AK by mass spectrometry. AK showed immunoreactivity against crab-allergenic sera in both native and denaturing conditions with 70% and 80% positive reactions, respectively. Additionally, a 1073 bp ORF was obtained which codes for a deduced sequence of 357 amino acids corresponding to AK with > 90% identity with other AKs. Structural homology model of AK showed two main domains with conserved / folding of phospho-guanidine kinases. BediPred and Discotope were used for epitope prediction analysis, which suggests eight possible linear epitopes and seven conformational epitopes, respectively; and shows to be similar to other crustaceans AKs. C. bellicosus AK was identified as an allergenic protein by IgE reactivity and immunobioinformatic analysis indicates that both linear and conformational epitopes could be located in the surface of C. bellicosus AK structure.

Optimization of growing conditions for pigments production from microalga Navicula incerta using response surface methodology and its antioxidant capacity.

Navicula incerta is a marine microalga distributed in Baja California, México, commonly used in aquaculture nutrition, and has been extended to human food, biomedical, and pharmaceutical industries due to its high biological activity. Therefore, the study aimed to optimize culture conditions to produce antioxidant pigments. A central composite experimental design and response surface methodology (RSM) was employed to analyze the best culture conditions. The medium (nitrogen-deficient concentrations), salinity (PSU = Practical Salinity Unity [g/kg]), age of culture (days), and solvent extraction (ethanol, methanol, and acetone) were the factors used for the experiment. Chlorophyll a (Chl a) and total carotenoids (T-Car), determined spectroscopically, were used as the response variables. The antioxidant capacity was evaluated by DPPH• and ABTS•+ radical inhibition, FRAP, and anti-hemolytic activity. According to the overlay plots, the optimum growth conditions for Chl a and T-Car production were the following conditions: medium = 0.44 mol·L-1 of NaNO3, salinity = 40 PSU, age of culture: 3.5 days, and solvent = methanol. The pigment extracts obtained in these optimized conditions had high antioxidant activity in ABTS•+ (86.2-92.1% of inhibition) and anti-hemolytic activity (81.8-96.7% of hemolysis inhibition). Low inhibition (33-35%) was observed in DPPH•. The highest value of FRAP (766.03 ± 16.62 µmol TE/g) was observed in the acetonic extract. The results demonstrated that RSM could obtain an extract with high antioxidant capacity with potential applications in the biomedical and pharmaceutical industry, which encourages the use of natural resources for chemoprevention of chronic-degenerative pathologies.

Jumbo squid (Dosidicus gigas) mantle collagen: extraction, characterization, and potential application in the preparation of chitosan-collagen biofilms.

Collagen-based biomaterials have been widely used due to its binding capabilities. However the properties and potential use of new collagen sources are still under investigation. Fish by-products are an excellent source of collagen. Thus, acid-soluble collagen (ASC) was extracted, and biochemical and physicochemically characterized from one under-utilized specie, jumbo squid (Dosidicus gigas). In addition, commercial chitosan (95-50%)-ASC (5-50%) blend films were successfully prepared by casting, and characterized by infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The molecular masses of the ASC subunits were about 190kDa, 110kDa, and 97kDa, the content of proline and hydroxyproline was 10.9% and 2.8%, respectively. The FT-IR and nuclear magnetic resonance spectra ((1)H NMR) confirmed collagen peptidic crosslinks, and one endothermic peak was found at 119 degrees C. The FT-IR spectrum showed that chitosan and ASC remain linked into the films mainly due to hydrogen bonding. The 85:15 (chitosan:ASC) ratio was selected for its thermal and mechanical analyses. The thermograms of this film indicated the presence of two peaks, one at 87-98 degrees C and the other at 142-182 degrees C. The chitosan:ASC blend produced a transparent and brittle film, with high percentage of elongation at break, and low tensile strength in comparison to chitosan films. D. gigas mantle might be useful as a new source of plasticizer agent in the preparation of biofilms in composites with chitosan.

Effect of a low-density polyethylene film containing butylated hydroxytoluene on lipid oxidation and protein quality of Sierra fish (Scomberomorus sierra) muscle during frozen storage.

Fresh sierra fish (Scomberomorus sierra) fillets were packed in low-density polyethylene films with butylated hydroxytoluene (BHT-LDPE) added. Fillets packed in LDPE with no BHT were used as controls (LDPE). The packed fillets were stored at -25 degrees C for 120 days in which the film released 66.5% of the antioxidant. The influence of the antioxidant on lipid and protein quality, lipid oxidation, muscle structure changes, and shear-force resistance was recorded. As compared to LDPE films, fillets packed in BHT-LDPE films showed lower lipid oxidation, thiobarbituric acid values (4.20 +/- 0.52 vs 11.95 +/- 1.06 mg malonaldehyde/kg), peroxide values (7.20 +/- 1.38 vs 15.15 +/- 1.48 meq/kg), and free fatty acids (7.98 +/- 0.43 vs 11.83 +/- 1.26% of oleic acid). Fillets packed in BHT-LDPE films showed less tissue damage and lost less firmness than fillets packed in LDPE. A significant relationship between lipid oxidation and texture was detected (R2 adjusted, 0.70-0.73). BHT-LDPE films may be used not only to prevent lipid oxidation but also to minimize protein damage to prolong the shelf life of sierra fish.