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Resumen El aumento de la resistencia a los antibióticos por parte de bacterias patógenas ha motivado la búsqueda de alternativas para disminuir su utilización. Dentro de las opciones propuestas se encuentra la terapia de antiadherencia, en la cual se utilizan moléculas análogas a los glicoepítopes que son reconocidos por las bacterias para impedir la unión de éstas al tejido celular. En este estudio se llevó a cabo la obtención de glicoconjugados por medio de la reacción de Maillard partiendo de albúmina sérica bovina (BSA) y oligosacáridos de quitosano (oligosacáridos sin ultrafiltrar, ultrafiltrados y ultrafiltrados acetilados), en proporción 1:1 (p/p) a tres temperaturas de incubación (50, 60 y 70 °C) por 30 min. La caracterización de los conjugados sintetizados se realizó utilizando electroforesis (SDS-PAGE), espectroscopía de infrarrojo y espectroscopía de fluorescencia. Se realizaron ensayos de reconocimiento usando aglutinina de germen de trigo (WGA) y bacterias [Escherichia coli (K88ac y K88+)]. La caracterización por medio de electroforesis y espectroscopía de infrarrojo evidenció la unión de los oligosacáridos de quitosano a la estructura de la BSA. Además, los ensayos evidenciaron el reconocimiento de las moléculas sintetizadas tanto por la lectina WGA como por las bacterias. Los glicoconjugados sintetizados sin ultrafiltrar ni acetilar mostraron resultados muy favorables en el reconocimiento por ambas bacterias, lo que constituye una ventaja práctica, ya que su implementación a mayor escala reduciría costos de producción
Abstract The increase in antibiotic resistance by pathogenic bacteria has motivated the search for alternatives to reduce the use of antibiotics. Among these alternatives is anti-adhesion therapy, in which molecules that mimic the glycoepitopes that recognise bacteria are used to prevent their binding to cellular tissue. In this study, glycoconjugates were obtained by means of the Maillard reaction starting from bovine serum albumin (BSA) and chitosan oligosaccharides (unfiltered oligosaccharides, ultrafiltered and acetylated ultrafiltered), in a ratio of 1:1 (w/w) at three incubation temperatures (50, 60 and 70 °C) per 30 min. The characterisation was performed using the techniques of electrophoresis (SDS-PAGE), infrared spectroscopy and fluorescence spectroscopy. Recognition assays were performed using wheat germ agglutinin (WGA) and Escherichia coli bacteria (K88ac and K88+). Characterisation by electrophoresis and infrared spectroscopy demonstrated the binding of chitosan oligosaccharides to the structure of BSA. In addition, the tests showed the recognition of the molecules synthesised by both the WGA lectin and the E. coli bacteria. The glycoconjugates synthesised without ultrafiltration or acetylation showed very favourable results in recognition with both bacteria, which is an advantage, since its implementation on a larger scale would reduce production costs.
Resumo O aumento da resistência aos antibióticos por bactérias patogênicas tem motivado a busca de alternativas para reduzir seu uso. Entre essas alternativas está a terapia anti-adesão, na qual são utilizadas moléculas análogas aos glicoepítopos que são reconhecidas pelas bactérias para impedir sua união ao tecido celular. Neste estudo, os glicoconjugados foram obtidos por meio da reação de Maillard a partir de albumina sérica bovina (BSA) e oligossacarídeos de quitosana (oligossacarídeos não ultrafiltrados, ultrafiltrados e acetilados ultrafiltrados), na proporção de 1:1 (p/p) em três temperaturas de incubação (50, 60 e 70 °C) durante 30 min. A caracterização dos conjugados sintetizados foi realizada utilizando a eletroforese (SDS-PAGE), espectroscopia de infravermelho e espectroscopia de fluorescência. Os ensaios de reconhecimento foram realizados utilizando aglutinina de germe de trigo (WGA) e bactérias [Escherichia coli (K88ac e K88+)]. A caracterização por meio de eletroforese e espectroscopia de infravermelho demonstrou a união dos oligossacarídeos de quitosana à estrutura da BSA. Além disso, os testes evidenciaram o reconhecimento das moléculas sintetizadas tanto pela lectina WGA quanto pelas bactérias. Os glicoconjugados sintetizados sem ultrafiltração ou acetilação apresentaram resultados muito favoráveis no reconhecimento por ambas as bactérias, o que é uma vantagem, visto que sua implementação em maior escala reduziria custos de produção.
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This investigation aimed to determine the effect of high-power ultrasonic pulses on the antioxidant, antibacterial, and antiproliferative activity of sorghum (Sorghum bicolor) lignin. A lignin yield of 7.35% was obtained using the organosolv method. Additionally, the best conditions of the ultrasonic pulses were optimized to obtain a more significant increase in antioxidant capacity, resulting in 10 min for all treatments, with amplitudes of 20% for DPPH and FRAP, 18% for ABTS, and 14% for total phenols. The effect of ultrasonic pulses was mainly observed with FRAP (1694.88 µmol TE/g), indicating that the main antioxidant mechanism of lignin is through electron transport. Sorghum lignin with and without ultrasonic pulses showed high percentages of hemolysis inhibition (>80%) at concentrations of 0.003 to 0.33 mg/mL. The AB blood group and, in general, all Rh- groups are the most susceptible to hemolysis. Lignin showed high anti-inflammatory potential due to heat and hypotonicity (>82%). A higher antimicrobial activity of lignin on Escherichia coli bacteria was observed. The lignins evaluated without sonication and sonication presented higher activity in the cell line PC-3. No effect was observed on the lignin structure with the FT-IR technique between sonication and non-sonication; however, the organosolv method helped extract pure lignin according to HPLC.
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Multi-drug resistant (MDR) bacteria have gained importance as a health problem worldwide, and novel antibacterial agents are needed to combat them. Silver nanoparticles (AgNPs) have been studied as a potent antimicrobial agent, capable of countering MDR bacteria; nevertheless, their conventional synthesis methods can produce cytotoxicity and environmental hazards. Biosynthesis of silver nanoparticles has emerged as an alternative to reduce the cytotoxic and environmental problems derived from their chemical synthesis, using natural products as a reducing and stabilizing agent. Sonoran Desert propolis (SP) is a poplar-type propolis rich in polyphenolic compounds with remarkable biological activities, such as being antioxidant, antiproliferative, and antimicrobial, and is a suitable candidate for synthesis of AgNPs. In this study, we synthesized AgNPs using SP methanolic extract (SP-AgNPs) and evaluated the reduction capacity of their seasonal samples and main chemical constituents. Their cytotoxicity against mammalian cell lines and antibacterial activity against multi-drug resistant bacteria were assessed. Quercetin and galangin showed the best-reduction capacity for synthesizing AgNPs, as well as the seasonal sample from winter (SPw-AgNPs). The SPw-AgNPs had a mean size of around 16.5 ± 5.3 nm, were stable in different culture media, and the presence of propolis constituents was confirmed by FT-IR and HPLC assays. The SPw-AgNPs were non-cytotoxic to ARPE-19 and HeLa cell lines and presented remarkable antibacterial and antibiofilm activity against multi-drug resistant clinical isolates, with E. coli 34 and ATCC 25922 being the most susceptible (MBC = 25 µg/mL), followed by E. coli 2, 29, 37 and PNG (MBC = 50 µg/mL), and finally E. coli 37 and S. aureus ATCC 25923 (MBC = 100 µg/mL). These results demonstrated the efficacy of SP as a reducing and stabilizing agent for synthesis of AgNPs and their capacity as an antibacterial agent.
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Chitosan-based film with and without antagonistic yeast was prepared and its effect against Penicillium italicum was evaluated. The biocompatibility of yeast cells in the developed films was assessed in terms of population dynamics. Furthermore, the impact on physicochemical properties of the prepared films with and without yeast cells incorporated were evaluated in terms of thickness, mechanical properties, color and opacity. Chitosan films with the antagonistic yeast entrapped exhibited strong antifungal activity by inhibiting the mycelial development (55%), germination (45%) and reducing the sporulation process (87%). Chitosan matrix at 0.5% and 1.0% was maintained over 9 days of cell viability. However, at 1.5% of chitosan the population dynamics was strongly affected. The addition of yeast cells only impacted color values such as a*, b*, chroma and hue angle when 1.0% of chitosan concentration was used. Conversely, luminosity was not affected in the presence of yeast cells as well as the opacity. Besides, the addition of antagonistic yeast improved the mechanical resistance of the films. The addition of D. hansenii in chitosan films improve their efficacy for controlling P. italicum, and besides showed desirable characteristics for future use as packaging for citrus products.
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The main chemical composition and pharmacological potential of propolis from arid and semi-arid regions of the Sonoran Desert have been previously reported. Caborca propolis (CP), from an arid zone of the Sonoran Desert, has shown a polyphenolic profile that suggests a mixed plant origin, presenting poplar-type markers, as well as a 6-methoxylated flavonoid, xanthomicrol, characteristic of Asteraceae plants. In addition, CP has shown significant antioxidant properties and antiproliferative activity on cancer cells. In this study, we analyzed the influence of collection time on the chemical constitution, antiproliferative activity and protective capacity of CP against reactive oxygen species (ROS), by using HPLC-UV-diode array detection (DAD) analysis, 3-(4,5-dimethylthiazol-2-yl)-2,5-Dimethyltetrazoliumbromide (MTT) and 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assays, as well as cellular antioxidant activity (CAA) assay on murine B-cell lymphoma M12.C3.F6 cells. HPLC-UV-DAD analyses of seasonally collected CP (one-year period) revealed quantitative differences among the most abundant CP constituents: pinocembrin, galangin, chrysin and pinobanksin-3-O-acetate. Though all seasonal samples of CP induced an antiproliferative effect in M12.C3.F6 cells, CP from autumn showed the highest inhibitory activity (IC50: 5.9 ± 0.6 µg/mL). The DPPH assay pointed out that CP collected in autumn presented the highest antioxidant potential (IC50: 58.8 ± 6.7 µg/mL), followed by winter (65.7 ± 12.2 µg/mL) and spring (67.0 ± 7.5 µg/mL); meanwhile, the summer sample showed a lesser antioxidant capacity (IC50: 98.7 ± 2.5 µg/mL). The CAA assay demonstrated that CP induced a significant protective effect against ROS production elicited by H2O2 in M12.C3.F6 cells. Pretreatment of M12.C3.F6 cells with CP from spring and autumn (25 and 50 µg/mL for 1 h) showed the highest reduction in intracellular ROS induced by H2O2 (1 and 5 mM). These results indicate that the antiproliferative effect and cellular antioxidant activity of CP are modulated by quantitative fluctuations in its polyphenolic profile due to its collection time.
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Sorghum is a cereal with little use in human diet; however, this grain can provide several nutrients and, additionally, has a high content of phenolic compounds concentrated in bran, which could be beneficial to human health due to its high antioxidant capacity. However, these bioactive compounds are bound within the cell wall matrix; it is necessary to release these compounds to take advantage of their antioxidant properties. The extrusion process increases the accessibility of bound phenolic compounds, breaking their bonds from the bran matrix. The aim of this study was to determine the optimal extrusion conditions for maximizing the phenolic compound content and antioxidant capacity of sorghum bran extrudate. The extrusion process factors evaluated were feed moisture (FM) from 25 to 35% and the fourth extrusion zone temperature (T) in the range of 140-180 °C. Analysis of variance and response surface analysis were used in the evaluation. The prediction coefficient, (FM)2, (T)2 and their interaction (FM)(T) significantly affected the free total phenolic compounds. The antioxidant capacity of the free total phenolic compounds was significantly affected by (FM)2 and (T)2. The optimal extrusion conditions were FM = 30% and T = 160 °C, which provided free total phenolic compounds with a value of 7428.95 µg GAE/g (predicted value: 7810.90 µg GAE/g) and antioxidant capacity with a value of 14.12 µmol TE/g (predicted value: 14.85 µmol TE/g). Results confirmed that extrusion process optimization was useful to increase the content of phenolic compounds and improved the antioxidant capacity of sorghum bran.
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Sorghum , Antioxidantes , Dieta , Grão Comestível , Humanos , FenóisRESUMO
Stenocereus thurberi is an endemic species in northwestern Mexico. It produces colorful fruits called pitayas that have an edible pulp. They have phytochemical compounds associated with biological activities. Ultrafiltration is a widely used method for the clarification of fruit juices and the recovery of phytochemicals. However, its effect has not been extensively studied in extracts. Therefore, the objective of this work is to study the effect of the ultrafiltration of pitaya extract (Stenocereus thurberi) on its phytochemical content, antioxidant capacity, and identification of phenolic compounds by UPLC-DAD-MS, providing greater knowledge about the pitaya. In this study, two extracts were analyzed, the unclarified extract (UE) and the clarified extract (CE). The antioxidant capacity was higher in the CE with 15.93 ± 0.42 mM TE/g, DPPH and 18.37 ± 0.016 mM TE/g, ABTS. The UPLC-MS analysis indicated the decrease in phenolic compounds in the CE and the presence of gallic acid and resorcinol, compounds that had not been identified in other species of Stenocereus spp. The correlation analysis indicated that all the phytochemicals present in the pitaya contribute significantly to the antioxidant capacity. The ultrafiltration process could be a viable option to improve the biological activity of the natural extracts.
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Antioxidantes/química , Cactaceae/química , Fenóis/química , Compostos Fitoquímicos/química , Cromatografia Líquida de Alta Pressão , Flavonoides/química , Flavonoides/isolamento & purificação , Frutas , México , Fenóis/isolamento & purificação , Compostos Fitoquímicos/isolamento & purificação , Extratos Vegetais/química , Espectrometria de Massas em Tandem , UltrafiltraçãoRESUMO
Cellulose nanofibers from durum wheat straw ( Triticum durum ) were produced and characterized to study their potential as reinforcement fibers in biocomposites. Cellulose was isolated from wheat straw by chemical treatment. Nanofibers were produced via an electrospinning method using trifluoroacetic acid (TFA) as the solvent. The nanofibers were 270 ± 97 nm in diameter. Analysis of the FT-IR spectra demonstrated that the chemical treatment of the wheat straw removed hemicellulose and lignin. XRD revealed that the crystallinity of the cellulose was reduced after electrospinning, but nanofibers remained highly crystalline. The glass transition temperature (T(g) value) of the fibers was 130 °C, higher than that of cellulose (122 °C), and the degradation temperature of the fibers was 236 °C. Residual TFA was not present in the nanofibers as assessed by the FT-IR technique.
