Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

In order to identify chemical and antioxidant properties of interest in the biopolymer industry, the chemical characterization of the juice of four variants of Opuntia megacantha cladodes was carried out; the variants present two degrees of maturity (tender and mature) and two different managements during their development (wild and cultivated). The degree of maturity of the cladodes was statistically significant (p ≤ 0.05), the juice of mature cladodes presented a greater amount of crude fiber and nitrogen-free material, while the juice of tender cladodes contains a greater amount of protein, ethereal extract and ashes. There was no significant statistical difference (p = 0.6917), in the content of phenols in the four studied variants, with concentrations between 165.6 and 176.6 mg GAE/mL; (2.18 and 3.61 mg GAE/g in dry weight). Ripe cladodes juices contain more of the different quantified sugars (p ≤ 0.05). Biopolymer films were prepared using clarified juice of tender wild cladodes, determining their tensile strength of 1.42 MPa, Young’s modulus of 1.77 MPa and elongation at breakage of 124.16%, it is considered that the juices characterized in this work can offer viable alternative to petroleum-derived polymers.

This study focused on recovering alkaline proteases from the viscera of Scomberomorus sierra through hydrophobic interaction chromatography. Three alkaline proteases were partially separated using this chromatographic technique; two of them, with molecular weights of 19 and 31 kDa, were identified as trypsin-like enzymes according to inhibition assays. The 31 kDa alkaline protease, the only isolated enzyme, was purified under following chromatographic conditions: ammonium sulfate 13% (w/v) and ethylene glycol 27% (w/v); this enzyme showed maximum activity at pH 9 – 10 and 50 – 60 °C and was strongly inhibited by soybean trypsin inhibitor (SBTI) and porcine trypsin inhibitor (TPI). A third alkaline protease with molecular weight of 20 kDa was partially separated and inhibited by tosyl phenylalanyl chloromethyl ketone (TPCK), showing optimum activity at pH 9 – 11 and 60 °C. These results show that the viscera of Scomberomorus sierra may be useful as source of proteases.

Continuous exposure to N-(phosphonomethyl) glycine (glyphosate) produces alterations on aquatic ecosystems, depending on the species or organism, concentration and exposure time. The aim of this research was to evaluate the median lethal concentration (LC50(24)) in Artemia franciscana, as well as the median population inhibitory concentration (IC50) and the coefficient of form (CF) in the cyanobacterium Microcystis aeruginosa in aquatic ecosystems. The results for A. franciscana were an LC50(24) 0.31 mg L-1, and on M. aeruginosa of an IC50(72) 53.95 mg L-1. About the study of the coefficient of form, in the control cells of M. aeruginosa it resulted in a CF≈1, while exposed to 72h-NOEC (No Observable Effect Concentration) was 2.95 mg L-1. The IC50(72) was 53.95 mg L-1 indicating that the cells remain spherical, however, there are significant changes in their volume and the cell surface exposed to IC50(72) of 7.69 ± 1.69 µm3 with 33% volume reduction compared to the control cell, which reflects the ecotoxicological dangers of this herbicide. Exposure to glyphosate resulted as category I (highly toxic) in A. franciscana and category II (toxic) in M. aeruginosa, according to the classification of the United States Environmental Protection Agency (U.S. EPA).

Mango pericarp powders (Mangifera indica L.) of Ataulfo, Keitt and Tommy Atkins cultivars were obtained by dehydration and grinding. The content of moisture, ash, fat, dietary fiber, antioxidant capacity and total phenols was evaluated. The cultivar with functional ingredient potential was Ataulfo with antioxidant capacity of 34,811 µmol ET g-1 and 7578 mg EAG 100 g-1 total phenol, and dietary fiber ≈ 20 %. All three cultivars can be considered as ingredients for adding or enriching fiber in food formulations.

Rieske/mononuclear oxygenases are a group of metalloenzymes that catalyzes the oxidation of a diversity of compounds, it is noteworthy their ability to oxidize contaminant xenobiotic compounds, these enzymes also take part in the biosynthesis of some commercial valuable products. They have a broad substrate specificity that makes them a group of enzymes with a high biotechnological potential that has not been exploited to date. The present review analyzes general aspects of the structure and function of this important group of enzymes. 

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.

Honey is a food product with high nutritional and pharmacological value. Most studies of this product have focused on studying the properties of honey produced by Apis mellifera, which has been used in alternative medicine, highlighting the antioxidant, antimicrobial and anti-inflammatory activities, among others. In this work, we identified the floral origin, the concentration of soluble protein and phenolic compounds, and we assessed the antioxidant and chelating activity of the honey produced by Melipona beecheii and Frieseomelitta nigra from the community of San Marcos in Tenosique, Tabasco, México. The results show that the honey produced by M. beecheii was of monofloral origin (Eugenia sp.); while that of F. nigra is of polyfloral origin, derived mainly from the species Piper sp., aff. Brosimum, Asteraceae, Ziziphus sp., Haematoxylum campechianum). Honey produced by F. nigra show higher concentration of phenolic compounds, it is more effective in entrapping the DPPH and superoxide radicals, and exhibits better copper chelating potential. The honey of M. beecheii has a higher capacity for uptake of ABTS radicals and chelation of iron. The uptake capacity of the hydroxyl radical was similar for both honeys. This work highlights the importance of having palynological and biochemical analyzes on the honeys of native stingless bees, because of their therapeutic potential, where for many species there is a lack of information.

Recently, vegetable oils modification to obtain methyl esters of fatty acids (FAME) or biodiesel has emerged as an alternative for substituting petroleum derivatives, due to the environmental and health problems generated with their use. Owing to its chemical structure it is possible to epoxidize these molecules and use them directly to produce plasticizers or lubricants. However, these can also be subject to modifications for improving their properties and, at best, serve as intermediaries in polyurethanes synthesis. Since epoxide conventional production methods are potential source of contamination, the use of enzymatic catalysts has been suggested as a sustainable or "green" alternative for their preparation, since they allow obtaining products with high purity and better yields. This article presents a review of the available literature focusing on the enzymatic epoxidation of the FAMEs, as well as their main applications.

Los alimentos a los que se les añaden probióticos (bacterias benéficas) constituyen uno de los sectores más importantes de los alimentos funcionales. Los productos lácteos son los principales vehículos para estas bacterias que producen un efecto benéfico a la salud, cuando se consumen vivas y en cantidades suficientes para adherirse al colon. Sin embargo, cada día crece el interés por desarrollar alimentos no lácteos como vehículo para probióticos. Los productos de origen vegetal son una buena alternativa para estas innovaciones. Tienen la ventaja de que son muy aceptados y accesibles para la población. Adicionalmente, representan una alternativa de consumo para poblaciones con dietas restringidas. Sin embargo, la incorporación de probióticos a estos productos requiere considerar varios criterios y vencer retos tecnológicos con la finalidad de conservarlos funcionalmente activos.

Two-component signaling circuits (TCS) allow bacteria to detect environmental cues and to produce adaptive responses. These signaling systems are based on autophosphorylation and phosphoryl-group transfers between histidine and aspartate containing sensor kinase and response regulator proteins. Upon reception of a specific stimulus the sensor kinase protein autophosphorylates, by either an inter- or intra-molecular reaction, and transphosphorylates its cognate response regulator, which, typically, acts as a transcriptional regulator, thereby triggering physiological responses. Frequently, in the absence of the stimulus, the sensor kinase proteins are responsible for the dephosphorylation of their cognate response regulators. Furthermore, a group of sensor kinases have additional functional domains that are involved in a forward phosphorelay for signal transmission and in a reverse phosphorelay for signal decay. As is the case of the autophosphorylation reaction, the phosphoryl-group transfers involved in the forward and reverse phosphorelay can occur either intra- or inter-molecularly. In this review, we highlight some important features of bacterial TCS, with special emphasis on the autophosphorylation and phosphoryl-group transfer events.