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Smilax aristolochiifolia root extract and its compounds chlorogenic acidand astilbin inhibit the activity of alpha-amylase and alpha-glucosidase enzymes
No full text"Regulating activities of -amylase and -glucosidase through the use of specific inhibitors is a main strategy for controlling type 2 diabetes. Smilax aristolochiifolia root decoctions are traditionally used in Mexico as hypoglycemic and for weight loss, but the active principles and mechanisms underlying such putative metabolic effects are yet unknown. Here, we isolated the major bioactive compounds from a hydroethanolic extract of S. aristolochiifolia root by fast centrifugal partition chromatography and evaluated their effects against pancreatic -amylase and yeast -glucosidase. A chlorogenic acid-rich fraction (CAF) inhibited -amylase activity with an IC50 value of 59.28 μg/mL in an uncompetitive manner and -glucosidase activity with an IC50value of 9.27 μg/mL in a noncompetitive mode. Also, an astilbin-rich fraction (ABF) inhibited -glucosidase activity with an IC50 value of 12.30 μg/mL, in a noncompetitive manner. CAF inhibition -amylase was as active as acarbose while both CAF and ABF were 50-fold more potent inhibitors of -glucosidase than acarbose. The molecular docking results of chlorogenic acid and astilbin with -amylase and -glucosidase enzymes correlated with the inhibition mechanisms suggested by enzymatic assays. Our results prove that S. aristolochiifolia roots contain chlorogenic acid and astilbin, which inhibit carbohydrates-hydrolyzing enzymes, suggesting a new mechanism for the hypoglycemic effect reported for this plant.
Application of seaweed, natural biopolymers, and carbon-based materials as a wastewater treatment of water-soluble hydrocarbons
Get PDF"Actualmente la liberación de hidrocarburos (HC) al medio acuático (> 6000 toneladas en 2016), es uno de los problemas emergentes de mayor impacto al ambiente. Una de las principales fuentes de emisión son los derrames de HC por actividades de la industria petroquímica. De acuerdo a estudios, los HC más solubles son los más tóxicos para organismos acuáticos. Las principales estrategias de respuesta contemplan el uso de tecnologías de adsorción. En años recientes, las investigaciones se han orientado a la búsqueda de materiales alternativos que permitan la remoción de contaminantes con capacidades de remoción similares a los adsorbentes comerciales. En este trabajo se evaluó la capacidad de biosorción de tres especies de macroalgas (pardas, verdes y rojas), a diferentes fuerzas iónicas. En los estudios de caracterización se detectó la presencia de los principales compuestos químicos presentes en la pared celular de los biomateriales. El incremento de la fuerza iónica a un valor hasta un valor de 0.5 M, no tiene un efecto detectable en la carga superficial de los biosorbentes, sin embargo la concentración de los grupos funcionales ácidos se mantuvo constante. La capacidad de adsorción de HC es mayor en biomasa del alga parda (M. pyrifera), donde el principal mecanismo se debe a la partición en la fase lipídica y compuestos de carbono no hidrolizable. La capacidad de adsorción de benceno por M. pyrifera disminuye a I > 0.45 M por la competencia de moléculas de agua por sitios activos en los biomateriales. Adicionalmente, mediante el uso de diseño de experimentos, se sintetizaron compositos a partir de la biomasa de M. pyrifera, quitosano (CS) y pectina. Los biomateriales fueron analizados en experimentos en lote y en continuo donde se demostró su factibilidad como biosorbentes para la remoción de los contaminantes de estudio. Por último, el óxido de grafeno (OG) es un alótropo de carbono con potencial aplicación en la remoción de contaminantes orgánicos en solución acuosa. Actualmente, su aplicación se ha visto limitada debido a su aglomeración y baja área específica (SBET). Ante esta problemática, la síntesis de sólidos laminares pilareados representa una alternativa al incrementar el área de adsorción y los sitios activos disponibles. El propósito principal de este estudio fue determinar el efecto de la co-precipitación de quitosano entre los espacios interlaminares del óxido de grafeno, y su afinidad por los principales hidrocarburos (HC) solubles en agua (benceno, tolueno y naftaleno). La proporción CS/OG = 0.1 empleando quitosano de bajo peso molecular, registró el mayor incremento del SBET (47 m2/g). Con el fin de elucidar los mecanismos de adsorción involucrados, se evaluó la afinidad por los HC de estudio a diferentes condiciones de pH, temperatura y presencia de materia orgánica"."Nowadays the recovery of low-molecular aromatic hydrocarbons (HC) released into natural bodies of water continues to be a challenging task. These contaminants cause severe consequences to the environment and the human health. The oil spill cleanup strategies are primarily designed to deal with HC heavy fractions accumulated in the water surface. Unfortunately, insufficient information is available regarding the treatment of dissolved fractions. Biosorption on macroalgae (Ma) biomass seems to be a potential alternative to overcome disadvantages associated with expensive costs and complexity of activated carbon production. Three representative samples of brown, green and red macroalgae seaweeds (Macrocystis pyrifera, Ulva expansa and Acanthophora spicifera, respectively) were evaluated to remove benzene and toluene from water, which is the most soluble hydrocarbons. To accomplish this objective, the influence of temperature and ionic strength on biosorption rate were also determined. Raw biomasses were characterized by different physical and chemical techniques to assess their potential as biosorbents and the mechanisms involved. Despite these advantageous properties of seaweed biomass, the physical characteristics (small particle size, low strength, and density) of such biomaterials are not viable for continuous process operation and make biomass challenging to apply. Therefore, the development of innovative low-cost techniques of immobilized biosorbents with particular attention to increasing their effectiveness in the biosorption process is mandatory. The objective of this research was to explore the performance of different biosorbent aggregates through different proportions of brown seaweed-chitosan-pectin on biosorption capacity of the three main soluble hydrocarbons (benzene, toluene, and naphthalene) in water. The biocomposite synthesis was optimized by application of the factorial design and response surface methodology. Moreover, a detailed chemical and physical characterization analysis, by textural properties, potentiometric titrations, elemental content, chemical stability, KBr-FT-IR, and TGA analysis, were performed to explain the adsorption mechanisms. Also, an optimized Ma-Pe-Ch biocomposite was used for BTEX and naphthalene removal in a fixed-bed column under different experimental conditions. Finally, alternative methods to functionalized graphene oxide with a water-dispersible material are needed to create GO composites for adsorption applications. By introducing molecules or other carbon-based components between GO sheets (pillared agents), an increase in the surface area of the material could be observed. The synthesis of different CS-GO composites achieved an optimized surface area of 47 m2/g (ratio CS/GO = 0.1). Various characterization techniques verified the presence of chitosan molecules between the GO sheets, creating grooves and high energetic adsorption sites. The hydrophobic effect and π-π interactions of the GO structures also with the chitosan (-OH) functional groups determined the favorable adsorption capacity in comparison with the un-modified GO".Durante la realización del trabajo el autor recibió una beca académica del Consejo Nacional de Ciencia y Tecnología (424187) y del Instituto Potosino de Investigación Científica y Tecnológica, A. C.
La investigación desarrollada en esta tesis fue financiada a través del programa de Proyectos de Desarrollo Científico para Atender Problemas Nacionales (PDCPN−01−247032)
Estructuración de redes de nanoalambres magnéticos asistida por ablación laser para modificar la anisotropía magnética efectiva
Get PDF"Se sintetizaron redes de nanoalambres magnéticos por deposición
electroquímica sobre membranas porosas de alúmina anodizada para producir
arreglos ordenados con geometrías bien definidas. Con este fin se utilizó un láser
XY controlado por computadora montado sobre una mesa. Se siguieron dos
caminos, el primero consistió en irradiar con láser las redes de alambres para
removerlos y generar arreglos microestructurados. En el segundo método se
depositó una capa orgánica sobre las membranas, con la finalidad de bloquear los
poros de la membrana e impedir el crecimiento de los alambres, posteriormente esta
capa se removió con el láser definiendo áreas específicas por las cuales crecieron
alambres. Se han estudiado las condiciones óptimas para poder realizar estos
procesos de manera controlada y reproducible, además se determinó la morfología
y las propiedades magnéticas de distintos arreglos de alambres por SEM y
magnetometría respectivamente. Los resultados mostraron que los nanoalambres
presentaron tamaños uniformes de aproximadamente 60 µm de largo (grosor de las
membranas) y 0.2 µm de diámetro, además, se encontró que la anisotropía
magnética total varió al introducir la estructuración. Estos cambios fueron
interpretados de acuerdo con un modelo del campo desmagnetizante efectivo en
ensambles de nanoalambres magnéticos, el cual incorpora los efectos combinados
de la geometría de los alambres y del arreglo geométrico que forman.""Magnetic nanowire arrays were synthesized by electrochemical deposition in porous anodic alumina membranes to produce ordered arrays with well-defined geometries. To this end, a computer-controlled XY láser mounted on a table has been used. Two paths were followed, the first consisted in laser irradiation of the nanowires to remove them and generate microstructured arrays. In the second method an organic layer is deposited over the membranes to block the pores and inhibit the growth of wires, afterwards certain areas of this layer were removed assisted by laser ablation, defining paths were the wire growth occurred. The optimal conditions have been studied to perform these processes in a controlled and reproducible way, in addition, the morphologies and magnetic properties of the different assemblies were determined by SEM and magnetometry. The results showed that the nanowires were uniform in size with approximately 200 nm in diameter and 60 µm in length, also, it was found that the total magnetic anisotropy varied when structuration patterns were introduced. These changes were interpreted in accordance to a model of effective demagnetizing field in magnetic nanowire assemblies, which incorporates the combined effects of geometry of the wires and the geometrical arrangement they form.
Caracterización de los elementos en cis que regulan negativamente la transcripción de los genes EPA mediante las proteínas del silenciamiento de Candida glabrata
No full text"La adherencia es un factor importante en la virulencia de distintos patógenos. En
Candida glabrata, los genes EPA (Epithelial Adhesin) son responsables de la mayor
parte de la adherencia a las células huésped y se localizan en regiones
subteloméricas donde se regulan por silenciamiento subtelomérico, el cual depende
de Rap1, las proteínas yKu y el complejo SIR. El gen EPA1, que codifica la adhesina
principal, forma un grupo con EPA2 y EPA3 en el telómero derecho del cromosoma E
(E-R). Entre EPA3 y el telómero, se encuentra un elemento que actúa en cis, el
protosilenciador Sil2126, que requiere el contexto de su telómero para ser funcional.
Sil2126 puede silenciar un gen reportero a 32 kb del telómero (donde normalmente no
hay silenciamiento). Encontramos que hay elementos situados en la región intergénica
entre EPA2 y EPA3 que se requieren para la actividad de Sil2126. Estos elementos
podrían ser los responsables de la especificidad de Sil2126 por su telómero. El
extremo 5’ de Sil2126 contiene sitios de unión putativos para Rap1 y Abf1 y estas
proteínas se unen al Sil2126 en su posición original y también cuando se coloca a -32
kb (Sil@-32kb). Sil@-32kb también puede reclutar Sir3, lo que sugiere la propagación
del silenciamiento hasta esta distancia. Utilizamos el ensayo de 3C (Chromosome
conformation capture) para determinar las frecuencias de interacciones entre Sil@-
32kb y Sil2126 (en su posición original) y varios puntos a lo largo de la región
subtelomérica E-R. Los datos revelaron que Sil@-32kb interactúa fuertemente con la
región intergénica entre EPA1 y EPA2 al formar un loop que resulta en la represión de
la expresión de EPA1. A su vez, Sil2126 puede interactuar con la región intergénica
entre EPA2 y EPA3. Proponemos que el mecanismo de acción del protosilenciador
Sil2126 es a través del reclutamiento de las proteínas de silenciamiento y la formación
de una superestructura que involucra diferentes interacciones entre los elementos que
actúan en cis y diversas proteínas.""Adherence is an important virulence factor in several pathogens. A higher virulence has been correlated with increased adherence and with an expansion of adhesinencoding genes. In Candida glabrata, the adherence to host cells is mainly mediated by EPA (Epithelial Adhesin) genes. Most of EPA genes are located in subtelomeric regions regulated by subtelomeric silencing, which depends on Rap1, yKu proteins and the SIR complex. Epa1 mediates most of the adherence to epithelial cells in vitro. The EPA1 gene forms a cluster with EPA2 and EPA3 in the right telomere of chromosome E (E-R). Between EPA3 and the telomere, there is a cis-acting element, the protosilencer Sil2126, which requires its own telomere context for its activity. Sil2126 can silence a reporter gene 32 kb away from the telomere (a region where normally there is no silencing). Our results showed that there are cis-acting elements located in the EPA2-EPA3 intergenic region that are required for Sil2126 activity, which perhaps are responsible for the Sil2126 telomere-specificity. The 5’ end of Sil2126 contains putative binding sites for Rap1 and Abf1; we found that these proteins bind to Sil2126 in its original position and also when it is placed at -32 kb (Sil@-32kb). Rap1 and Abf1 also bind to other regions in the E-R subtelomeric region. In addition, we detected that Sil@-32kb can recruit Sir3, suggesting the propagation of the silencing up to that distance. We used 3C (Chromosome conformation capture) assays to measure crosslinking frequencies between Sil@-32kb and Sil2126 in its original position across the E-R subtelomeric region. These assays revealed that Sil@-32kb interacts with the EPA1-EPA2 intergenic region forming a loop that results in the repression of EPA1. On the other hand, Sil2126 interacts with the EPA2-EPA3 intergenic region. We propose that the mechanism of action of Sil2126 is through the recruitment of silencing proteins to form a superstructure involving different interactions between cis-acting elements and diverse proteins.
In vitro inhibitory activity of Acca sellowiana fruit extract on end products of advanced glycation
Get PDF"Introduction Hyperglycemia plays an important role in the pathogenesis of diabetic complications, as it increases protein glycation, as well as the progressive accumulation of advanced glycation end products (AGEs), which are complex structures that produce fluorescence. The glycation reaction raises the levels of protein carbonyl, N ?-(carboxymethyl)lysine (CML), and fructosamine and decreases the level of thiol groups. Methods In the present study, the antiglycation activity was determined by fluorescence intensity using the bovine serum albumin (BSA)/glucose, CML method, and the level of fructosamine. The oxidation of proteins was determined by the carbonyl protein content and thiol groups. Results The results show that the hexane extract of Acca sellowiana (FOH) at different concentrations (0.30-5 mg/ml) significantly inhibited the formation of AGEs in the BSA/glucose model during the 4 weeks of the study. FOH reduced the levels of fructosamine and CML. Our results showed a significant effect of FOH in the prevention of oxidative damage of proteins, as well as an effect on the oxidation of thiol groups and carbonyl proteins. Conclusion The present study indicates that FOH is effective in inhibiting the glycation of proteins in vitro, so it can prevent or ameliorate the chronic conditions of diabetes associated with the formation of AGEs.
Wrinkled nitrogen-doped carbon belts
Get PDF"Graphene, carbon nanotubes, and fullerenes are nanomaterials with outstanding properties such as electrical, thermal, mechanical strength, flexibility, and high surface area. These nanomaterials are used as building blocks for the construction of novel and astonishing 3D-dimensional networks. In the present work, nitrogen-doped carbon belt (N-CB) structures containing wrinkled carbon fibres as building blocks were synthesized under unstable conditions in a chemical vapour deposition experiment. N-CB structures with 0.2-3.0 microns of wide and 350?nm thick were assembled from complex individual wrinkled carbon fibres grown on Co/Cu films. These complex structures have a tubular appearance, showing holed and wrinkled graphite layers. Sulphur and copper atoms drastically affect the catalytic role of cobalt, changing the conventional growth of carbon nanotubes. Chemical functional groups, N-doping, and carbons hybridizations involved in the winkled carbon fibres are investigated. These findings provides a novel material that can be used as an excellent oxygen-reduction reaction catalyst or nano-electronics component.
Distribution of arsenic and risk assessment of activities on soccer pitches irrigated with arsenic-contaminated water
Get PDF"The aim of this research was to estimate the risk of human exposure to arsenic due to sporting activities in a private soccer club in Mexico, where arsenic-contaminated water was regularly used for irrigation. For this purpose, the total concentration in the topsoil was considered for risk assessment. This was accomplished through three main objectives: (1) measuring arsenic concentrations in irrigation water and irrigated soils, (2) determining arsenic spatial distribution in shallow soils with Geographical Information Systems (GIS) using geostatistical analysis, and (3) collecting field and survey data to develop a risk assessment calculation for soccer activities in the soccer club. The results showed that the average arsenic concentrations in shallow soils (138.1 mg/kg) were 6.2 times higher than the Mexican threshold for domestic soils (22 mg/kg). Furthermore, dermal contact between exposed users and contaminated soils accounted for a maximum carcinogenic risk value of 1.8 × 10−5, which is one order of magnitude higher than the recommended risk value, while arsenic concentrations in the irrigation water were higher (6 mg/L) than the WHO’s permissible threshold in drinking water, explaining the contamination of soils after irrigation. To the best of our knowledge, this is the first risk study regarding dermal contact with arsenic following regular grass irrigation with contaminated water in soccer pitches.
“Síntesis y caracterización de óxido de grafeno reducido y dopado con N mediante un proceso solvotérmico”
Get PDFTesis (Maestría en Nanociencias y Materiales)"El objetivo principal de este proyecto de tesis es el estudio de la obtención de grafeno derivado químicamente, mediante la reducción química de óxido de grafeno. Esta técnica es una de las más prometedoras empleadas en la actualidad, ya que permite la obtención de material a gran escala y a un bajo costo, donde la calidad del grafeno obtenido es dependiente de las condiciones óptimas de oxidación y reducción, mismas que han sido evaluadas en este trabajo. La sección experimental se divide en dos partes: la síntesis de óxido de grafito mediante el método de Hummers mejorado reportado por Tour y colaboradores; y la reducción química de óxido de grafeno mediante un proceso solvotermico utilizando una mezcla de H2O / DMF (3:1) para aprovechar la excelente solubilidad que presenta el GO sintetizado y las propiedades reductoras que presenta el H2O supercrítica, así como, las propiedades reductoras de la DMF a altas temperaturas. Además de generar un dopaje de N, utilizando a la DMF como fuente de este. La efectividad en los procesos de oxidación y reducción se determinó caracterizando los materiales sintetizados mediante técnicas básicas de espectroscopía y microscopía, así como difracción de rayos x. También, se realizó la medición de la conductividad de los materiales obtenidos para corroborar una reestructuración de la red grafítica en el óxido de grafeno reducido obtenido. De acuerdo con los resultados obtenidos en la caracterización, se encuentra una reducción parcial efectiva y un dopaje de nitrógeno > 5%. Además, el material obtenido se encuentra definido como material mesoporoso en base a lo establecido por la IUPAC. La red grafítica fue reestructurada, pasando de un GO aislante a un material rGO semiconductor. En base a los resultados, este material puede ser ocupado en aplicaciones electrónicas como: almacenamiento de energía y fabricación de electrodos para supercapacitores.""The main objective of this thesis project is the study of the production of chemically derived graphene by the chemical reduction of graphene oxide. This technique is one of the most promising today, since it allows the production of large scale and low cost material, where the quality of the graphene obtained is dependent on the optimum conditions of oxidation and reduction, which have been evaluated in this work. The experimental section is divided into two parts: the graphite oxide synthesis by the improved Hummers method reported by Tour et al. And the chemical reduction of graphene oxide by a solvothermal process using a mixture of H2O/DMF (3:1) to take advantage of the excellent solubility of the synthesized GO and the reducing properties of the supercritical H2O, as well as reducing properties of DMF at high temperatures. In addition to generating a doping of N, using the DMF as a source of this. The effectiveness in the oxidation and reduction processes was determined by characterizing the materials synthesized by basic techniques of spectroscopy and microscopy, as well as x-ray diffraction. Also, the conductivity of the obtained materials was verified to corroborate a restructuring of the graphite network in the reduced graphene oxide obtained. According to the results obtained in the characterization, there is an effective partial reduction and a nitrogen doping> 5%. In addition, the material obtained is defined as mesoporous material based on what is established by IUPAC. The graphite network was restructured, going from an insulating GO to a semiconductor rGO material. Based on the results, this material can be occupied in electronic applications such as: energy storage and manufacture of electrodes for supercapacitors.
H2Ti3O7 nanotubes decorated with silver nanoparticles for photocatalytic degradation of atenolol
Get PDF"The photocatalytic degradation/adsorption process of the β-blocker atenolol (ATL) under UV irradiation is described using two types of silver decorated catalysts: silver/titania and silver/titanates. The silver ions were reduced on the surface of TiO2-P25-Degussa using gallic acid. Silver/titanates were prepared by a microwave-assisted hydrothermal method using the silver/titania as the starting material to obtain the hydrogen titanate (H2Ti3O7) structure with tubular morphology. These materials were characterized by X-ray diffraction, UV-Vis spectroscopy, N2 physisorption, temperature programmed reduction, TEM, and FTIR spectroscopy. During the photocatalytic process, the ATL molecules were completely converted to amino-diol byproducts. It is the first time that these materials have been applied during the photocatalytic process in the degradation of pharmaceuticals products. The success of the silver nanoparticles (2 nm) consists of the homogeneous distribution over the surface of titanate nanotubes inhibiting the hole/electron recombination promoting the oxidation process. The Ag@H2Ti3O7 with a concentration of silver as 1.0% shows the highest adsorption/degradation of ATL than the Ag@TiO2 and the P25-Degussa. The great performance in the reuse test consists in the strong attachment of the silver nanoparticles on the titanium surface that inhibits the silver lixiviation during the photocatalytic tests.
Opuntia spp.: characterization and benefits in chronic diseases
Get PDF"Opuntia species have been used for centuries as food resources and in traditional folk medicine for their nutritional properties and their benefit in chronic diseases, particularly diabetes, obesity, cardiovascular diseases, and cancer. These plants are largely distributed in America, Africa, and the Mediterranean basin. Opuntia spp. have great economic potential because they grow in arid and desert areas, and O. ficus-indica, the domesticated O. species, is used as a nutritional and pharmaceutical agent in various dietary and value-added products. Though differences in the phytochemical composition exist between wild and domesticated (O. ficus-indica) Opuntia spp., all Opuntia vegetatives (pear, roots, cladodes, seeds, and juice) exhibit beneficial properties mainly resulting from their high content in antioxidants (flavonoids, ascorbate), pigments (carotenoids, betalains), and phenolic acids. Other phytochemical components (biopeptides, soluble fibers) have been characterized and contribute to the medicinal properties of Opuntia spp. The biological properties of Opuntia spp. have been investigated on cellular and animal models and in clinical trials in humans, allowing characterization and clarification of the protective effect of Opuntia-enriched diets in chronic diseases. This review is an update on the phytochemical composition and biological properties of Opuntia spp. and their potential interest in medicine.