RESUMEN
Tyrosinase inhibitors are capable of preventing unfavorable enzymatic browning of fruits and vegetables. In this study, the capacity of Acacia confusa stem bark proanthocyanidins (ASBPs) to inhibit tyrosinase activity was evaluated. ASBPs were shown to be a high-potential inhibitor of tyrosinase with IC50 values of 92.49 ± 4.70 and 61.74 ± 8.93 µg/mL when using L-tyrosine and L-DOPA as the substrate, respectively. The structural elucidation performed with UV-vis, FT-IR spectroscopy, ESI-MS and thiolysis coupled to HPLC-ESI-MS suggested that ASBPs had structural heterogeneity in monomer units and interflavan linkages and consisted mainly of procyanidins dominant with B-type linkages. To gain insights into the inhibitory mechanisms of ASBPs against tyrosinase, different spectroscopic and molecular docking methods were further conducted. Results validated that ASBPs possessed the ability to chelate copper ions and could prevent the oxidation process of substrates by tyrosinase. The hydrogen bond formed with Lys-376 residue played a key role in the binding force of ASBPs with tyrosinase that induced a certain alteration in the microenvironment and secondary structure of tyrosinase, resulting in the enzymatic activity being ultimately restricted. It was also observed that ASBPs treatment effectively inhibited the activities of PPO and POD to retard the surface browning of fresh-cut asparagus lettuce and thus extended their shelf-life. The results provided preliminary evidence supporting the exploitation of ASBPs into potential antibrowning agents for the fresh-cut food industry.
Asunto(s)
Acacia , Proantocianidinas , Monofenol Monooxigenasa , Lactuca/metabolismo , Proantocianidinas/química , Acacia/metabolismo , Verduras/metabolismo , Simulación del Acoplamiento Molecular , Corteza de la Planta/metabolismo , Espectroscopía Infrarroja por Transformada de Fourier , Inhibidores Enzimáticos/químicaRESUMEN
The influence of pH on the biosynthesis of orange Monascus pigments (OMPs) in Monascus ruber M7 was investigated. Under acidic fermentation conditions, pigment mixtures predominantly rich in OMPs were obtained. HPLC analysis revealed the presence of four orange components (O1-O4) and four yellow components (Y1-Y4) in the mixtures, and the dominant ones were O1 and O3, which accounted for 56.0% to 75.9% of the total pigments in the pH range 3-6. Subsequently, O1 and O3 were identified by LC-DAD-ESI/MS as Rubropunctatin and Monascorubrin, respectively. The yield of OMPs was observed to be inversely dependent on pH. At pH 3, large amounts of OMPs with high purity (79.1%) were accumulated. A real-time quantitative PCR analysis revealed that the expression of genes related to the biosynthesis of OMPs in M. ruber M7 was upregulated at acidic pH as compared to neutral pH, and the variation in the level of expression of these genes with pH was consistent with the production of OMPs. These results indicated that the large accumulation of OMPs under acidic condition involved the acidic pH-induced transcription of genes related to the biosynthesis of OMPs. These results would contribute towards the development of an efficient technology for large-scale production of OMPs.
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Medios de Cultivo/química , Monascus/crecimiento & desarrollo , Monascus/metabolismo , Pigmentos Biológicos/metabolismo , Cromatografía Liquida , Fermentación , Concentración de Iones de Hidrógeno , Pigmentos Biológicos/química , Pigmentos Biológicos/clasificación , Espectrometría de Masa por Ionización de ElectrosprayRESUMEN
In the past few years, melamine has been illegally added into dairy products to increase the apparent crude protein levels. If humans or animals drink the milk adulteration of melamine, it can form insoluble melamineâ»cyanurate crystals in their kidneys which causes kidney damage or even death. In the present work, we constructed a simple and label-free fluorescent method for melamine detection based on melamine-thymine recognition. SYBR Green I was utilized as a reporter for this method as it did not require any modification or expensive equipment. In the absence of melamine, polythymine DNA was digested by Exo I, which caused a decrease in the fluorescence signal. In the presence of melamine, the polythymine DNA was able to fold into a double chain structure, however this was done with the help of T-melamine-T mismatches to prevent degradation. Then, the SYBR Green I combined with the double-stranded DNA to result in an intense fluorescence signal. The limit of detection in this method was 1.58 µM, which satisfied the FDA standards. This method also had a good linear relationship within the range of 10â»200 µM. In addition, this new method has a good selectivity to distinguish melamine from the component of milk. As a result, we developed a simple and highly selectivity method for melamine detection.
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Contaminación de Alimentos/análisis , Timina/química , Triazinas/análisis , Triazinas/química , Animales , ADN/química , ADN/metabolismo , Exodesoxirribonucleasas/metabolismo , Fluorescencia , Colorantes Fluorescentes/análisis , Colorantes Fluorescentes/química , Límite de Detección , Leche/químicaRESUMEN
Pickering emulsions were co-stabilized by nanoliposome (NL) and thermally denatured ovalbumin (DOVA) based on the induction of OVA with strong particle characteristics through thermal denaturation. DOVA-NL particles were spherical and their sizes were mainly distributed between 50 and 100 nm. The surface tension and interfacial tension of DOVA-NL were significantly reduced, and the surface hydrophobicity, amphiphilicity and free -SH content of DOVA were enhanced after complexation with NL. The content of α-helix and ß-sheet in DOVA decreased, whereas the content of ß-turn and random coil increased after complexation with NL. Hydrophobic interactions, hydrogen bonding and electrostatic forces played a vital role in the interactions between NL and DOVA, leading to conformational changes in DOVA. The number of binding sites between NL and DOVA was more than one, and the interaction between NL and DOVA was exothermic and spontaneous. The emulsification index showed that DOVA-NL-stabilized Pickering emulsions (DNPE) were significantly more stable than DOVA-stabilized emulsions. DOVA-NL particles adsorbed at the oil-water interface and the droplet size of DNPE was smaller than that of DOVA-stabilized emulsions. This study suggests that it may be an effective strategy to improve the stability of Pickering emulsions through co-stabilization with NL and DOVA.
RESUMEN
The stability enhancement of proanthocyanidin-loaded liposomes (PC-Lip) via surface decoration with oxidized konjac glucomannan (OKGM) was investigated. The encapsulation efficiency and drug loading capacity of OKGM-coated PC-Lip (OKGM-PC-Lip) rose significantly. The average size and PDI of OKGM-PC-Lip increased, while the zeta potential decreased compared to those of PC-Lip. PC-Lip membrane fluidity reduced after coating with OKGM. The morphology of OKGM-PC-Lip showed that OKGM "halo layer" was formed on the liposome surface. Hydrogen bonding played an indispensable role in the combination between OKGM and PC-Lip, and the phase transition temperature of PC-Lip slightly increased after coating with OKGM. The retention rate of OKGM-PC-Lip was higher than that of PC-Lip at extreme pH. In vitro release, no significant difference in cumulative release was detected between OKGM-PC-Lip and PC-Lip at gastric stage, while the cumulative release rate of OKGM-PC-Lip was remarkably lower than that of PC-Lip at intestinal stage. The antioxidant activity of OKGM-PC-Lip was notably higher than that of PC-Lip. These results suggested that the resistance of PC-Lip to external influences was fruitfully enhanced after coating with OKGM. Compared with other polysaccharides, OKGM-coated liposomes may be more promising and advantageous in functional foods due to the polysaccharide's benefits to human health.
Asunto(s)
Antioxidantes , Liposomas , Mananos , Oxidación-Reducción , Proantocianidinas , Liposomas/química , Proantocianidinas/química , Mananos/química , Antioxidantes/química , Propiedades de Superficie , Tamaño de la Partícula , Liberación de Fármacos , Estabilidad de Medicamentos , Concentración de Iones de HidrógenoRESUMEN
Surface browning of plant-derived fresh-cut products is mainly caused by conversion of the phenolic compounds into o-quinones under tyrosinase catalysis. In this study, the rarely reported complex tannins from Euryale ferox seed shell (ECTs) constituted by the units of 35.60% condensed tannins and 64.40% hydrolysable tannins were shown to suppress the activity of tyrosinase efficiently, supporting the exploitation of ECTs into novel anti-browning agents. However, the utilization of ECTs in food preservation is often restricted because of their chemical instability to external environment. Further fabrication of nanoliposomes loaded with ECTs (ECTs-NLs) herein was carried out to improve the stability of ECTs. DLS, TEM, FTIR, DSC and XRD confirmed that ECTs were encapsulated into nanoliposomes successfully, and ECTs-NLs appeared as vesicle-like spherical morphology with favorable encapsulation efficiency, uniform particle size distribution and negative zeta-potential. The resulting ECTs-NLs were relatively stable in the dark at 4 °C. Nanoliposomal encapsulation significantly enhanced ECTs stability, thus protecting inhibitory effect of ECTs against tyrosinase. Furthermore, anti-browning evaluation proved that ECTs-NLs had distinct advantages over free ECTs in alleviating surface browning of fresh-cut asparagus lettuces. These results suggested that nanoliposomes were effective in stabilizing ECTs and ECTs-NLs could be potentially applied to the fresh-cut food industry.
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Asparagus , Liposomas , Monofenol Monooxigenasa , Semillas , Taninos , Liposomas/química , Semillas/química , Asparagus/química , Taninos/química , Monofenol Monooxigenasa/antagonistas & inhibidores , Nanopartículas/química , Tamaño de la Partícula , Nymphaeaceae/químicaRESUMEN
The duration of storage significantly influences the quality and market value of Qingzhuan tea (QZT). Herein, a high-resolution multiple reaction monitoring (MRMHR) quantitative method for markers of QZT storage year was developed. Quantitative data alongside multivariate analysis were employed to discriminate and predict the storage year of QZT. Furthermore, the content of the main biochemical ingredients, catechins and alkaloids, and free amino acids (FAA) were assessed for this purpose. The results show that targeted marker-based models exhibited superior discrimination and prediction performance among four datasets. The R2Xcum, R2Ycum and Q2cum of orthogonal projection to latent structure-discriminant analysis discrimination model were close to 1. The correlation coefficient (R2) and the root mean square error of prediction of the QZT storage year prediction model were 0.9906 and 0.63, respectively. This study provides valuable insights into tea storage quality and highlights the potential application of targeted markers in food quality evaluation.
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Camellia sinensis , Almacenamiento de Alimentos , Metabolómica , Té , Té/química , Análisis Multivariante , Camellia sinensis/química , Análisis Discriminante , Catequina/análisis , Catequina/química , Aminoácidos/análisis , Aminoácidos/química , Alcaloides/análisis , Alcaloides/química , Cromatografía Líquida de Alta Presión , Extractos Vegetales/química , Extractos Vegetales/análisisRESUMEN
The interaction mechanism between nanoliposomes (NL) and a soybean protein isolate (SPI) was investigated via the complexation between NL and two major components of SPI, i.e., ß-conglycinin (7S) and glycinin (11S). The endogenous fluorescence emissions of 7S and 11S were statically quenched after complexation with NL, and the polarity of the SPI fluorophore increased. The interaction between NL and SPI was exothermic and spontaneous, 7S/11S secondary structures were altered, and more hydrophobic groups were exposed on protein surfaces. Moreover, the NL-SPI complex had a large zeta potential to attain system stability. Hydrophobic forces and hydrogen bonds played vital roles in the interaction between NL and 7S/11S, and a salt bridge was also involved in the NL-11S interaction. The binding characteristics between NL and 7S/11S were chiefly governed by the protein characteristics, such as amino acid composition, surface hydrophobicity, and advanced structure. These findings could deepen the understanding of the interaction mechanism between NL and SPI.
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Globulinas , Proteínas de Soja , Proteínas de Soja/química , Globulinas/química , Antígenos de Plantas/química , Proteínas de Almacenamiento de Semillas/química , Glycine max/químicaRESUMEN
It's generally believed that the longer the storage, the better the quality of dark tea, but the chemical differences of Qingzhuan tea (QZT) with different storage years is still unclear. Herein, in this work, an untargeted metabolomic approach based on SWATH-MS was established to investigate the differential compounds of QZT with 0-9 years' storage time. These QZT samples were roughly divided into two categories by principal component analysis (PCA). After orthogonal projections to latent structures discriminant analysis (OPLS-DA), 18 differential compounds were putatively identified as chemical markers for the storage year variation of QZT. Heatmap visualization showed that the contents of catechins, fatty acids, and some phenolic acids significantly reduced, flavonoid glycosides, triterpenoids, and 8-C N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (EPSFs) increased with the increase of storage time. Furthermore, these chemical markers were verified by the peak areas corresponding to MS2 ions from SWATH-MS. Based on the extraction chromatographic peak areas of MS and MS2 ions, a duration time prediction model was built for QZT with correlation coefficient R2 of 0.9080 and 0.9701, and RMSEP value of 0.85 and 1.24, respectively. This study reveals the chemical differences of QZT with different storage years and provides a theoretical basis for the quality evaluation of stored dark tea.
Asunto(s)
Catequina , Té , Té/química , Flavonoides/análisis , Metabolómica/métodos , Catequina/análisis , IonesRESUMEN
The surface characteristics and emulsifying properties of whey proteins (WP) after complexation with nanoliposomes (NL) were investigated. WP surface hydrophobicity enhanced after complexation with NL, and it indicated the exposure increase of WP hydrophobic groups. WPNL interfacial tension significantly decreased compared with that of WP. The interfacial protein content of WPNL-stabilized emulsions was slightly different from that of WP-stabilized emulsions. WP emulsifying properties were significantly improved after complexation with NL. The mean sizes and polydispersity indexes of WPNL-stabilized emulsion droplets were smaller than those of WP-stabilized emulsion droplets. The absolute zeta-potential values of WPNL-stabilized emulsions were greater than those of WP-stabilized emulsions. Electrostatic repulsion played a vital role in WPNL-stabilized emulsion stability. Moreover, surface and emulsifying properties of WPNL were changed by exterior factor-induced alteration of protein advanced structures. The emulsifying properties of WP after complexation with NL were improved due to the modification of WP surface characteristics.
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Emulsionantes , Emulsionantes/química , Emulsiones/química , Interacciones Hidrofóbicas e Hidrofílicas , Proteína de Suero de Leche/químicaRESUMEN
Condensed tannins the polyphenolic compounds that are widespread in plants have been proved to have antitumor potential. Here, we purified the bioactive condensed tannins from leaves of Ulmus pumila L. and explored their structural characteristics, antitumor effect on TFK-1 cholangiocarcinoma cells as well as the related potential mechanism. The UV-Vis, FT-IR spectroscopy, ESI-Full-MS, and thiolysis-HPLC-ESI-MS demonstrated that U. pumila condensed tannins (UCTs) consisted essentially of procyanidins with epicatechin as the main flavan-3-ol extension unit. The UCTs could significantly reduce the survival rate of human cholangiocarcinoma TFK-1, SK-CHA-1, and MZ-CHA-1 cells with the better inhibitory effect on TFK-1 cell proliferation. Flow cytometric assay showed that UCTs affected TFK-1 survival by G2/M phase arrest and inducing apoptosis in a dose-dependent manner. In addition, a total of 6592 differentially expressed genes (DEGs), consisting of 94 upregulated and 6498 downregulated DEGs, were identified between untreated and UCTs-treated TFK-1 cells using RNA-seq technology. Enrichment analysis based on the KEGG database revealed that these DEGs were closely associated with cell cycle and p53 apoptotic signaling pathways. Furthermore, qRT-PCR confirmed that treatment of UCTs to TFK-1 cells caused significant changes in the expression of cyclin E, cdc25 A, cytochrome c, caspase-3, and caspase-8. These results indicated that UCTs exhibited the growth inhibition effect on TFK-1 cells possibly via G2/M cell cycle arrest and activation of caspase-cascade to induce apoptosis, and had potential as an anti-cholangiocarcinoma drug for further development. PRACTICAL APPLICATIONS: Ulmus pumila L. as a valuable tree species has been widely used in fields of medicine and food. Condensed tannins, the polyphenolic compounds widespread in plants, have been proved to have antitumor potential and be safe to normal cells. In this study, the condensed tannins from leaves of U. pumila (UCTs) remarkably suppressed cholangiocarcinoma (CCA) cell viability possibly via G2/M cell cycle arrest and activation of caspase-cascade to induce apoptosis. The results provided evidence for the application of UCTs as a potential therapeutic drug for CCA tumor.
Asunto(s)
Neoplasias de los Conductos Biliares , Catequina , Colangiocarcinoma , Proantocianidinas , Ulmus , Apoptosis , Neoplasias de los Conductos Biliares/tratamiento farmacológico , Neoplasias de los Conductos Biliares/metabolismo , Neoplasias de los Conductos Biliares/patología , Conductos Biliares Intrahepáticos/metabolismo , Conductos Biliares Intrahepáticos/patología , Caspasa 3/metabolismo , Caspasa 8/genética , Caspasa 8/metabolismo , Caspasa 8/farmacología , Caspasas/metabolismo , Caspasas/farmacología , Caspasas/uso terapéutico , Catequina/farmacología , Puntos de Control del Ciclo Celular , División Celular , Colangiocarcinoma/tratamiento farmacológico , Colangiocarcinoma/metabolismo , Colangiocarcinoma/patología , Ciclina E/metabolismo , Ciclina E/farmacología , Citocromos c/metabolismo , Citocromos c/farmacología , Citocromos c/uso terapéutico , Humanos , Proantocianidinas/farmacología , Espectroscopía Infrarroja por Transformada de Fourier , Proteína p53 Supresora de Tumor , Ulmus/metabolismoRESUMEN
Tyrosinase is a critical enzyme related to various pigmentation disorders and browning of fruits and vegetables. In this study, a novel inhibitor pentagalloylglucose (PGG) against tyrosinase was prepared from tannic acid with the chemical structure elucidated using HPLC, ESI-MS, 1H- and 13C NMR. Its inhibitory effect and the underlying mechanism on tyrosinase were explored by enzyme kinetics, UV-scanning, copper-ion chelation, fluorescence, circular dichroism, fourier transform infrared spectroscopy and molecular docking simulation. Results revealed that the yield of PGG reached 18.0% and the purity was up to 99.09%. PGG was a high-potential inhibitor of tyrosinase with IC50 values of (15.54 ± 0.56) × 10-6 and (50.89 ± 3.34) × 10-6 mol/L for monophenolase and diphenolase, respectively. PGG could disturb the formation of dopachrome and had strong capacity to chelate copper ions. The fluorescence of tyrosinase was efficiently quenched by PGG through a static mechanism. The binding of PGG to tyrosinase was a spontaneous exothermic process that induced unfolding of the tyrosinase structure to expose more buried hydrophobic residues. Docking results implied that PGG interacted with tyrosinase by forming hydrogen bonds with amino acid residues Glu-173, Glu-208, Lys-158, Lys-180, Gln-44 and Gln-159. This study would enhance our understanding of the inhibitory mechanism of PGG on tyrosinase at the molecular level and provide scientific guidance for the application of PGG in food and pharmaceutical industries.
Asunto(s)
Cobre , Monofenol Monooxigenasa , Inhibidores Enzimáticos/química , Taninos Hidrolizables , Cinética , Simulación del Acoplamiento MolecularRESUMEN
In this work, nitrogen doped carbon dots (NCDs) were synthesized through one step hydrothermal reaction using citric acid and ethylenediamine as precursors. The prepared NCDs exhibit high quantum yield of 67.4%, good stability, excellent selectivity and sensitivity. It was found that the NCDs have potential as a fluorescence sensor for the detection of Hg2+. Under optimal conditions, good linearity between the change in NCDs fluorescence intensity and Hg2+ concentration was obtained in the range of 0.3 to 2.0 µM with a detection limit at 0.24 µM. The possible detection mechanism was static quenching of NCDs by Hg2+. The established method was successfully applied to the determination of Hg2+ in beverage samples. The results indicated that the NCDs-based sensor has potential for detection of Hg2+ in real beverage sample.
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Mercurio , Puntos Cuánticos , Bebidas , Carbono , Colorantes Fluorescentes , Límite de Detección , Mercurio/análisis , Nitrógeno , Espectrometría de FluorescenciaRESUMEN
The interaction mechanism between liposomes (Lips) and whey protein isolates (WPI) with different mass ratios was explored in this paper. After binding with different concentration of Lips, the changes in hydrophilic and hydrophobic regions of WPI were investigated with fluorescein isothiocyanate (FITC) and pyrene fluorescence probes. The spatial structure changes of WPI were further characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy, and circular dichroism. The results indicated that the structure of WPI was changed due to binding with Lips in hydrophilic and hydrophobic groups. The binding process might result in the migration, recombination, and alignment of WPI and Lip groups. Moreover, the oil-water interfacial tension with WPI decreased from 9.20 mN/m to 3.29 mN/m upon increasing the Lip-to-WPI ratio. This work suggests that the physiochemical properties of Lip-WPI complexes could be manipulated by adjusting the Lip-to-WPI ratio. This study shed some light on the mechanism explanation of the WPI structural changes due to the interaction with Lips during food processing.
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Interacciones Hidrofóbicas e Hidrofílicas , Liposomas/metabolismo , Proteína de Suero de Leche/metabolismo , Rastreo Diferencial de Calorimetría , Liposomas/química , Espectroscopía Infrarroja por Transformada de Fourier , Tensión Superficial , Proteína de Suero de Leche/químicaRESUMEN
Laoshan green teas plucked in summer and autumn were measured by high performance liquid chromatography-diode array detector (HPLC-DAD). After baseline correction, the fingerprints data were resolved by multivariate curve resolution-alternating least squares (MCR-ALS) and a total of 57 components were acquired. Relative concentrations of these components were afterwards applied to distinguish plucking seasons using principal component analysis (PCA), support vector machines (SVM) and partial least squares-discriminant analysis (PLS-DA). For both SVM and PLS-DA models, the total recognition rates of training set, cross-validation and testing set were 100%, 91.3% and 100%, respectively. Besides, three variable selection methods were employed to determine characteristic components for the authentication of summer and autumn teas. Results showed that PLS-DA model based on three characteristic components selected by VIP possesses identical predictive ability as the original model. This study demonstrated that our proposed strategy is competent for the authentication of plucking seasons of Laoshan green tea.
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Cromatografía Líquida de Alta Presión , Análisis de los Alimentos/métodos , Informática , Té/química , Análisis Discriminante , Fraude/prevención & control , Análisis de los Mínimos Cuadrados , Análisis de Componente Principal , Estaciones del AñoRESUMEN
Ovalbumin (OVA) is an important protein emulsifier. However, it is unstable near the isoelectric point pH, which limits its applications in the food industry. Polysaccharides may be explored to tackle this challenge by improving its pH-dependent instability. In this work, carboxymethyl cellulose (CMC) was used as a model polysaccharide to mix with OVA near its isoelectric point (pH 4.7) with subsequent mild heating at 60 °C for 30 min. The molecular interactions between OVA and CMC were comprehensively studied via a series of characterizations, including turbidity, zeta potential, intrinsic fluorescence, surface hydrophobicity, circular dichroism (CD) spectra and Fourier transform infrared spectroscopy (FTIR). The droplet sizes of the emulsions prepared by OVA-CMC were measured to analyze emulsifying property and stability. The results indicated that free OVA was easily aggregated due to loss of surface charges, while complexing with CMC significantly inhibited OVA aggregation before and after heating owing to the strong electrostatic repulsion. In addition, OVA exposed more hydrophobic clusters after heating, which resulted in the growth of surface hydrophobicity. Altogether, the heated OVA-CMC complexes presented the best emulsifying property and stability. Our study demonstrated that complexing OVA with CMC not only greatly improved its physicochemical properties but also significantly enhanced its functionality as a food-grade emulsifying agent, expanding its applications in the food industry, as development of emulsion-based acidic food products.
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Carboximetilcelulosa de Sodio/química , Ovalbúmina/química , Dicroismo Circular , Emulsionantes/química , Concentración de Iones de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas , Punto Isoeléctrico , Concentración Osmolar , Espectroscopía Infrarroja por Transformada de Fourier , Electricidad Estática , TemperaturaRESUMEN
In this study, the adsorption/desorption characteristics of rapeseed meal polysaccharides extract on four resins (HP-20, D3520, XAD-16, and AB-8) were evaluated. The results indicated that HP-20 resin had the best purification effect. Based on static adsorption test, the kinetics and isotherms of the four resins for protein and polysaccharide were investigated. The adsorption test showed that the pseudo-second-order kinetics model and the Freundlich isotherm model were more suitable for explanation of the adsorption process for protein and polysaccharide. Static desorption test showed that the highest protein desorption ratios of HP-20, D3520, and AB-8 resins could be obtained with 60% ethanol solution as eluate, and the highest protein desorption ratios of XAD-16 resin could be obtained with 40% ethanol solution as eluate. Dynamic adsorption/desorption tests of HP-20 resin showed that the deproteinization ratio was 91% and the polysaccharide recovery ratio was 62% when the treatment amount was 1.5 BV. Compared with three traditional methods, HP-20 resin adsorption method that the deproteinization ratio was 82% was more potent than the three traditional methods for purifying polysaccharides from rapeseed meal. In addition, UV/vis spectroscopy showed that most of the protein was absorbed by resins, and FT-IR spectroscopy indicated that the purity of the polysaccharide after purification was improved. Rapeseed meal polysaccharides could be effectively deproteinized using HP-20 resin, and it was suitable for purifying polysaccharides from rapeseed meal.
RESUMEN
In this study, the encapsulation of goose blood hydrolysate (GBH) was performed within nanoliposomes. We investigated the physicochemical properties, stability, antioxidant indices, the morphology of nanoparticles, the digestion stability in simulated gastrointestinal fluid, differential scanning calorimetry (DSC) analysis, and Fourier transform infrared (FTIR) spectroscopy. GBH was successfully encapsulated into nanoliposomes using reverse-phase evaporation method. The entrapment efficiency of GBH-loaded nanoliposomes was about 70.99 ± 2.85%, the average particle size was 93.3 ± 2.45 nm, the zeta-potential of GBH-loaded nanoliposomes was -30 mV, and the morphology of GBH-loaded nanoliposomes was characterized by transmission electron microscope. Moreover, the results of DSC and FTIR showed that the GBH nanoliposome was more stable than the empty liposomes due to hydrogen bond complexation between liposome and GBH. The release of GBH from nanoliposomes could be significantly controlled, and the release ratios were 48.9 ± 2.96% in simulated gastric fluid and 59.9 ± 5.30% in simulated intestinal fluid, respectively, proving that degradation rate of antioxidant activities of GBH encapsulated in nanoliposomes was decreased. In conclusion, nanoliposomes embedding is a promising and effective way to increase the stability of hydrolysates from GBH and produce various types of functional food.
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Antioxidantes/química , Proteínas Sanguíneas/química , Gansos/sangre , Liposomas/química , Nanopartículas/química , Animales , Rastreo Diferencial de Calorimetría , Tamaño de la Partícula , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
In this paper, we describe a simple and highly sensitive fluorescence strategy of mercury ions based on exonuclease III (Exo III)-aided target recycling amplification to ensure sensitivity. With an ultra high sensitivity (1 pM), our strategy has been simple and cost-effective, which does not need any artificial modification fluorescence groups, and can be carried out in a pot. It also shows excellent selectivity. Therefore, our new method provides an effective platform for mercury-ion detection.
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Técnicas Biosensibles/métodos , Exodesoxirribonucleasas/metabolismo , Límite de Detección , Mercurio/análisis , Sondas de ADN/química , Sondas de ADN/metabolismo , Espectrometría de FluorescenciaRESUMEN
In the present work, a simple design of "turn-on" fluorescence method for mercury ion was developed and explored based on specific T-Hg-T mismatches as a recognizer and N-methyl mesoporphyrin IX (NMM)/G-quadruplex DNA system as a reporter. The titration experiment showed that the mercury-ion concentration and the fluorescence intensity signal change exhibited a consistent linear correlation within the 50 to 500 nM range with a detection limit down to 12.9 nM. In a selectivity experiment, our method showed obvious selectivity against other metal ions, being consistent with other reported detection methods of mercury ion based on the specific reactivity of T-Hg-T mismatches. Our method was then successfully employed to detect mercury ion in pond water with excellent reliability.