RESUMO
This investigation employed molten globule state ß-lactoglobulin nanoparticles (MG-BLGNPs) for encapsulating linalool (LN) combined with carboxymethyl chitosan (CMC) coating to enhance the shelf-life of fresh-cut apples. The effect of different MG structures on the encapsulation efficiency of BLGNPs and the properties of coating was studied. Structural characterization and molecular simulation showed structural differences between heat-induced MG state (70-BLGNPs, heated at 70 °C for 1 h) and sodium dodecyl sulfate-co-heat-induced MG state (SDS/70-BLGNPs, treated with 0.192 mg/mL SDS for 10 min, then heated at 70 °C for 1 h), with the latter being more unfolded. LN self-assembles into MG-BLGNPs, among the generated particles, SDS/70-BLG@LN exhibits stronger binding effect and higher LN loading capacity. Integration of MG-BLG@LN into CMC enhanced coating's mechanical properties and adhesion to fresh-cut apples. The SDS/70-BLG@LN/CMC coating showed superior preservation on fresh-cut apples during storage, reducing enzymatic browning, membrane lipid oxidation, and microbial growth while maintaining hardness and overall quality.
RESUMO
Fucoxanthin (Fx) possesses multiple bioactivities such as antitumor, antioxidant and anti-inflammatory activities, but its application is limited due to the poor water solubility, low bioavailability, and instability to some external harsh conditions. In this study, a stable inclusion complex of Fx and 2-hydroxypropyl-ß-cyclodextrin (2-HP-ß-CD) was prepared with the aid of ultrasound, which was characterized by scanning electron microscope, Fourier transform infrared spectroscopy, powder X-ray diffraction, and differential scanning calorimetry techniques. The phase solubility analysis and absorption spectroscopy results showed that Fx formed stoichiometry 1:2 inclusion complex with 2-HP-ß-CD, and this could be well proved by molecular simulation. Structural analyses and molecular docking study indicated that Fx was successfully encapsulated into the cavity of 2-HP-ß-CD, promoting it soluble in water and stable against heat, storage and gastrointestinal environments. In addition, Fx/2-HP-ß-CD inclusion complex exhibited excellent antitumor activity against HCT116 and Caco-2 cell lines with IC50 values of 12.0 µΜ and 14.86 µΜ, respectively. Therefore, it could be a potentially promising way to promote the application of Fx in pharmaceuticals and functional foods by HP-ß-CD encapsulation strategy.
Assuntos
Água , Humanos , 2-Hidroxipropil-beta-Ciclodextrina/química , Solubilidade , Simulação de Acoplamento Molecular , Células CACO-2 , Varredura Diferencial de Calorimetria , Difração de Raios X , Espectroscopia de Infravermelho com Transformada de Fourier/métodosRESUMO
The present study aimed to investigate the inhibition mechanism of polyphenols from Phyllanthus emblica Linn. fruit (PEF, family Euphorbiaceous) on acetylcholinesterase (AChE). Interaction assay, enzyme kinetics, spectroscopic methods, and molecular simulations were performed. Results showed that myricetin, quercetin, fisetin, and gallic acid were the most active components in PEF, because of their low docking scores and strong inhibition ability on AChE with IC50 values of 0.1974 ± 0.0047, 0.2589 ± 0.0131, 1.0905 ± 0.0598 and 1.503 ± 0.0728 mM, respectively. Among them, the results of kinetic study showed that myricetin, quercetin, and fisetin reversibly inhibited AChE in a competitive manner, while gallic acid inhibited it through a noncompetition type. The interaction assay implied that a combination of the four polyphenols at the selected concentrations manifested a synergistic inhibition effect on AChE in a mixed inhibition type. Fluorescence and UV-vis spectrophotometry revealed that the active PEF polyphenols could strongly quench the intrinsic fluorescence of AChE via a static quenching mechanism. Circular dichroism spectroscopy analysis indicated that the active PEF polyphenols gave rise to the secondary structure changes of AChE by increasing the content of α-helix and reducing ß-sheet and random coil conformation. The molecular dynamics simulation results validated that all the four docked polyphenol-AChE complexes were relatively stable according to their root-mean-square distance, root-mean-square fluctuations, solvent accessible surface area, radius of gyration values and hydrogen bonds evaluations during the whole simulation process. Overall, our study provides a creative insight into the further utilization of PEF polyphenols as functional components in exploring natural AChE inhibitors.
Assuntos
Acetilcolinesterase , Phyllanthus emblica , Acetilcolinesterase/metabolismo , Frutas/metabolismo , Ácido Gálico , Cinética , Simulação de Acoplamento Molecular , Phyllanthus emblica/metabolismo , Polifenóis/farmacologia , Estrutura Secundária de Proteína , Quercetina , Análise EspectralRESUMO
In this work, 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized cellulose nanocrystals (TOCNs) were loaded into sodium alginate/chitosan multilayer film as nanofillers to investigate the modulation of the surface charge density of TOCNs on the film properties. First, the surface charge density of TOCNs was controlled by adjusting the carboxyl content and morphological size by varying the oxidant dosage. After oxidation, TOCN with higher surface charge density was observed to display a higher crystallinity, a more open internal structure, a better dispersibility and a slightly weaker thermal stability. In addition, a 15-layer film composed of sodium alginate and chitosan, called (SA/CH)15, was constructed by layer-by-layer assembly. Both in situ deposition monitoring and free-standing multilayer film formation indicated that TOCNs relied on strong electrostatic interactions and hydrogen bonding to achieve a compact and uniform interlayer and a thinner thickness of (SA/CH)15, which was more evident at a high surface charge density. The addition of TOCNs also enhanced the mechanical properties, thermal stability, hydrophobicity, and barrier properties of (SA/CH)15. In particular, the resulting sodium alginate/chitosan multilayer film exhibited an improved packaging performance when nanocomposite was performed using TOCN with a surface charge density of 3.22 ± 0.11 e nm-2.
Assuntos
Alginatos/química , Celulose/química , Quitosana/química , Nanofibras/química , Nanopartículas/química , Celulose Oxidada , Interações Hidrofóbicas e Hidrofílicas , Fenômenos Mecânicos , Microscopia Eletrônica de Transmissão , Nanocompostos/química , Nanocompostos/ultraestrutura , Nanofibras/ultraestrutura , Nanopartículas/ultraestrutura , Oxirredução , Espalhamento a Baixo Ângulo , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Propriedades de Superfície , Difração de Raios XRESUMO
In this study, the nanocomposite film (SA-CS@CuO/ZnO) composed of sodium alginate (SA) and chitosan (CS) functionalized by copper oxide nanoparticles (CuONPs) and zinc oxide nanoparticles (ZnONPs) was fabricated, then its antibacterial mechanisms against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were systematically investigated. When the contents of CuONPs and ZnONPs reached 1.5 % (w/w) and 0.5 % (w/w), respectively, the SA-CS@CuO/ZnO exhibited great mechanical, barrier, and optical properties. Moreover, the incorporation of ZnONPs enhanced the photocatalytic ability of SA-CS@CuO/ZnO, producing a high level of reactive oxygen species under light irradiation. Further, antibacterial results showed that SA-CS@CuO/ZnO treatment inhibited the growth of E. coli and S. aureus higher than 60 % in the dark and exceeded 90 % under light irradiation. This was also manifested in the incompleteness of bacterial cell structure, accompanied by unstable cellular redox balance and DNA disruption. The functions of differentially expressed genes screened by transcriptome analysis were mainly involved in membrane transport, cell wall and membrane synthesis, cellular antioxidant defense system, cell membrane and DNA repair system. The changes in bacterial transcriptional regulation reflected the disturbance in the physiological activities and loss of cell integrity, leading to damage of bacterial cells or death.
Assuntos
Nanocompostos , Nanopartículas , Óxido de Zinco , Antibacterianos/farmacologia , Cobre , Escherichia coli , Staphylococcus aureusRESUMO
This study aimed to reveal the interaction and inhibitory mechanisms of tangeretin (TAN), nobiletin (NBT), and their acidic hydroxylated forms, 5-demethyltangeretin (5-DT) and 5-demethylnobiletin (5-DN) on porcine pancreatic lipase (PPL) using spectroscopic techniques and molecular dynamics (MD) simulation. PPL inhibition assay showed that the inhibitory activity of NBT (IC50 value of 3.60 ± 0.19 µM) was superior to those of three polymethoxylated flavones (PMFs), indicating it may be related to the methoxy groups at the 3'-position in its molecular structure. Inhibition kinetic analyses demonstrated that the inhibition types of the 4 PMFs were consistent with the mixed inhibition model, which agreed well with the results from the ultraviolet-visible (UV-Vis) spectroscopy, Circular dichroism (CD), fluorescence spectroscopy, molecular docking, and MD simulation that PMFs could bind to the PPL catalytic site and non-catalytic site, affecting the normal spatial conformation of PPL and weakening its ability to decompose the substrate. All these findings suggest that PMFs are a kind of natural lipase inhibitors, and NBT has the potential as a lipase inhibition precursor because of its unique flavone skeleton structure.
Assuntos
Citrus/química , Flavonas/farmacologia , Lipase/metabolismo , Extratos Vegetais/farmacologia , Animais , Frutas/química , Cinética , Simulação de Acoplamento Molecular/métodos , Simulação de Dinâmica Molecular , Pâncreas/efeitos dos fármacos , Pâncreas/metabolismo , SuínosRESUMO
The effects of purity of tea polysaccharides (TPS) on its five antioxidant activities and hypoglycemic activities in vitro were studied. The results showed that the higher the purity of TPS, the lower the antioxidant capacity. The purity of FTPSI is the highest (sugar content 80.72%), but its antioxidant activities were lower than those of Fujian tea polysaccharides (FTPS) and FTPSII. The antioxidant activity of tea polysaccharide is related to its protein and polyphenol content (Pearson r > .90). The protective effect of Zhejiang tea polysaccharides and FTPS on human umbilical vein endothelial cells (HUVEC) was better than that of its purified fractions. The inhibition rates of FTPSII (5 and 2 mg/ml) on α-glucosidase (32.76%) and α-amylase (-11.93%) were higher than those of FTPS and FTPSII. Purification does not change the basic structure of TPS. This study has certain reference value for the study of the antioxidant activities of TPS. Meanwhile, TPS can be used as a potential resource with hypoglycemic function. PRACTICAL APPLICATIONS: A large number of studies have shown that TPS have antioxidant activity. However, several studies considered that the antioxidant activity of TPS mainly comes from the residues of tea polyphenols. Therefore, the in vitro and cell antioxidant activities of TPS were studied in this paper. We believe that both glycoprotein and tea polyphenol are antioxidants of tea, and tea polysaccharide perform preferable effect on hypoglycemic. HUVEC cell model and four in vitro antioxidant test methods were used to study the antioxidant activities of TPS, and two enzyme inhibition activities were used to study the hypoglycemic effect of TPS, in order to provide a theoretical basis for the study of biological activity of TPS.
Assuntos
Antioxidantes , Chá , Antioxidantes/farmacologia , Células Endoteliais , Humanos , Hipoglicemiantes/farmacologia , Polissacarídeos/farmacologiaRESUMO
Zein nanoparticles (ZNPs) have limited use as a result of its poor colloidal stability. The goal of this paper is to stabilize ZNPs using a sulfated anionic polysaccharide-dextran sulfate (DS). Zein/DS composite nanoparticles (ZDSNPs) were fabricated by antisolvent precipitation method at pH 4.0 with an optimal zein-to-DS ratio of 1:2 (w/w). ZDSNPs exhibited good stability to pH, heating and storage. Additionally, ZDSNPs showed spherical structures formed primarily by electrostatic attractions, hydrogen bonding and hydrophobic interactions. The incorporation of DS led to the change in secondary structure of zein. The surface hydrophobicity of ZNPs reduced owing to the deposition of DS. And ZDSNPs were basically nontoxic to normal colonic epithelial cell lines-NCM460 cell lines. ZDSNPs were successfully used to encapsulate curcumin. The encapsulation efficiency of curcumin-loaded ZDSNPs (ZDSCNPs) was 85.37%, which was significantly higher than that of curcumin-loaded ZNPs. In addition, ZDSCNPs exhibited improved storage stability and bioaccessibility of curcumin.
Assuntos
Curcumina/administração & dosagem , Sulfato de Dextrana/química , Portadores de Fármacos/química , Nanopartículas/química , Zeína/química , Materiais Revestidos Biocompatíveis/química , Sistemas de Liberação de Medicamentos , Estabilidade de Medicamentos , Temperatura Alta , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Análise EspectralRESUMO
Here, an enzyme mimic inspired by serine proteases was developed for the degradation of PAEs. This enzyme mimic, comprised an active site (SHD), a self-assembling polypeptide (LKLKLKL), a spacer (GGG) and a polymerizable site (DOPA) and showed high activity towards the degradation of DEHP in cells.
Assuntos
Dietilexilftalato/metabolismo , Ésteres/metabolismo , Ácidos Ftálicos/metabolismo , Serina Proteases/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Dietilexilftalato/química , Dietilexilftalato/farmacologia , Ésteres/química , Ésteres/farmacologia , Células HeLa , Humanos , Concentração de Íons de Hidrogênio , Tamanho da Partícula , Ácidos Ftálicos/química , Ácidos Ftálicos/farmacologia , Serina Proteases/química , Propriedades de Superfície , TemperaturaRESUMO
In this study, aggregation of fucoxanthin (FX) and its effects on binding and delivery properties of whey proteins were explored. Initially, the H- and J-aggregates of FX were successfully prepared by adjusting the water/ethanol ratio and water-dripping rate. The transition from J- to H-aggregates was observed over the standing time. Then, the molecular arrangement of FX H-aggregates was analyzed using the point-dipole approximation model and molecular dynamics, showing that their intermolecular distance and angle were about 5.0-6.7 Å and -35° to 35°, respectively. The transformation of J- to H-aggregates was also observed during molecular dynamics, with a shortened intermolecular distance, a reduced solvent accessible surface area, an enhanced interaction force, and a narrowed dihedral angle. Further, the interactions of whey proteins with different forms of FX were investigated, indicating that both ß-lactoglobulin and whey protein isolates could form complexes with the monomers, H-aggregates, and J-aggregates of FX. In terms of affinity, whey proteins bound FX monomers more strongly than aggregates. Furthermore, the complexes comprising whey proteins and monomeric FX had better delivery capabilities than aggregated FX, manifested in encapsulation efficiency, physical stability, and bioaccessibility.
Assuntos
Proteínas do Soro do Leite/química , Xantofilas/química , Concentração de Íons de Hidrogênio , Lactoglobulinas/química , Simulação de Dinâmica Molecular , Agregados Proteicos , Ligação ProteicaRESUMO
In order to rapidly and efficiently excavate antihypertensive ingredients in Todarodes pacificus, its myosin heavy chain was hydrolyzed in silico and the angiotensin-converting enzyme (ACE) inhibitory peptides were predicted using integrated bioinformatics tools. The results showed the degree of hydrolysis (DH) theoretically achieved 56.8% when digested with papain, ficin, and prolyl endopeptidase (PREP), producing 126 ACE inhibitory peptides. By predicting the toxicity, allergenicity, gastrointestinal stability, and intestinal epithelial permeability, 30 peptides were finally screened, of which 21 had been reported and 9 were new. Moreover, the newly discovered peptides were synthesized to evaluate their in vitro ACE inhibition, showing Ile-Ile-Tyr and Asn-Pro-Pro-Lys had strong effects with a pIC50 of 4.58 and 4.41, respectively. Further, their interaction mechanisms and bonding configurations with ACE were explored by molecular simulation. The preferred conformation of Ile-Ile-Tyr and Asn-Pro-Pro-Lys located in ACE were successfully predicted using the appropriate docking parameters. The molecular dynamics (MD) result indicated that they bound tightly to the active site of ACE by means of coordination with Zn(II) and hydrogen bonding and hydrophobic interaction with the residues in the pockets of S1 and S2, resulting in stable complexes. In summary, this work proposed a strategy for screening and identifying antihypertensive peptides from Todarodes pacificus.
Assuntos
Inibidores da Enzima Conversora de Angiotensina/química , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Decapodiformes/química , Peptídeos/química , Peptídeos/farmacologia , Animais , Decapodiformes/metabolismo , Descoberta de Drogas , Avaliação Pré-Clínica de Medicamentos , Ativação Enzimática/efeitos dos fármacos , Hidrólise , Conformação Molecular , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Cadeias Pesadas de Miosina/química , Cadeias Pesadas de Miosina/metabolismo , Relação Quantitativa Estrutura-AtividadeRESUMO
The purpose of this work is to stabilize zein nanoparticles with anionic polysaccharides-chondroitin sulfate (CS) to overcome the poor colloidal stability of zein nanoparticles. The average molecular weight of CS was 20.51â¯kDa and the disaccharide composition of CS was 70.71% monosulfated disaccharide Di2S and 29.29% disulfated disaccharide Di2,6 diS. Zein/CS composite nanoparticles were fabricated by antisolvent precipitation method at pHâ¯4.0. The optimal mass ratio of zein to CS was 1:1 (w/w). Zein/CS composite nanoparticles showed mean size of 148â¯nm and PDIâ¯<â¯0.2, maintaining great stability at pHâ¯3.0 to 8.0. Meanwhile, these prepared nanoparticles were also stable to heat treatment and was stable to a range of ionic strength of 0-15â¯mM at pHâ¯4.0 and 0-10â¯mM at pHâ¯7.0. The composite nanoparticles exhibited regular spherical structures, and CS was deposited on the surface of zein mainly by electrostatic interactions. In the process, the addition of urea and sodium dodecyl sulfate indicated that it also involved both hydrogen bonding and hydrophobic interactions. In addition, cytotoxicity assay on human renal epithelial cells-293 cells indicated that zein/CS composite nanoparticles were essentially nontoxic.
Assuntos
Precipitação Química , Sulfatos de Condroitina/química , Sulfatos de Condroitina/isolamento & purificação , Nanopartículas/química , Nanotecnologia/métodos , Solventes/química , Zeína/química , Temperatura Alta , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Concentração Osmolar , Propriedades de SuperfícieRESUMO
In the present study, a bilayer film composed of chitosan and alginate was produced by layer-by-layer casting and crosslinking by oxidized ferulic acid. The effects of different film components on mechanical, permeable and optical properties of the film were systematically investigated and the optimum concentrations were determined. The results of scanning electron microscopy and thermogravimetric analysis showed that the crosslinked bilayer film had a smoother and more uniform appearance than the uncrosslinked bilayer film, while the thermal stability was not significantly different. In addition, the infrared measurements confirmed the existence of crosslinking. Subsequently, citric acid was added as an active compound to the bilayer film, which endows the film with antioxidant capacity. Its optimum concentration was also determined by measuring the mechanical, permeable and optical properties of the film. Finally, the active bilayer film was applied to preserve the postharvest cherry tomatoes. The result found that it could well regulate the ascorbate-glutathione cycle in cherry tomatoes and alleviate the accumulation of oxidative damage during postharvest.
Assuntos
Alginatos/farmacologia , Ácido Ascórbico/metabolismo , Quitosana/farmacologia , Glutationa/metabolismo , Membranas Artificiais , Solanum lycopersicum/efeitos dos fármacos , Solanum lycopersicum/metabolismo , Alginatos/química , Antioxidantes/química , Quitosana/química , Fenômenos Mecânicos , Análise Espectral , TermogravimetriaRESUMO
In this study, a novel vector for fucoxanthin (FX) was constructed using the ligand-binding property of whey protein isolate and its subsequent heteroprotein complex coacervation with lysozyme. The results showed that FX could quench the intrinsic fluorescence of the whey protein isolate by a static mechanism, indicating that they could spontaneously form a nanocomplex through non-covalent interactions. Moreover, the structural and electrostatic properties of the resulting whey protein were different from those before the binding of FX, and this could be well explained by molecular dynamics simulation. The size and ζ-potential tests showed that when the whey protein isolate was combined with FX and then coacervated with lysozyme, the heteroprotein ratio and pH, which affect the coacervation process, also changed compared to those of the free whey protein isolate. FT-IR spectroscopy results showed that FX was successfully encapsulated into complex coacervates. In addition, the heteroprotein system exhibited a higher loading efficiency and also provided a better protection for FX in heating, storage, and simulated gastrointestinal environments.
Assuntos
Muramidase/química , Proteínas do Soro do Leite/química , Xantofilas/química , Animais , Biocatálise , Galinhas , Concentração de Íons de Hidrogênio , Ligação Proteica , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Chitosan-alginate films were prepared through layer-by-layer assembly combined with ferulic acid crosslinking. Their mechanical properties, opacity, and hydrophobicity were compared to films prepared by direct mixing, crosslinking alone, and LBL assembly alone. Thermogravimetric analysis, X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectroscopy were used to characterize the films and analyze their formation mechanism. The results indicated that the layer-by-layer assembly and ferulic acid crosslinking combination increased the tensile strength and light-blocking ability of the films. In addition, the films had a lower water vapor transmission rate, swelling degree, and water solubility, as well as higher hydrophobicity. Scanning electron microscopy showed a good compatibility between the film components of the film prepared by the combination technique. The structural characterization results revealed some strong interactions among the amino, carboxyl, and hydroxyl groups of the ferulic acid, chitosan, and sodium alginate in the film. The driving force for film formation was the generation of non-covalent bonds among the film components rather than covalent bonds.
Assuntos
Alginatos/química , Quitosana/química , Ácidos Cumáricos/química , Fenômenos Mecânicos , Fenômenos Ópticos , Água/químicaRESUMO
Marine-derived angiotensin-I converting enzyme (ACE) inhibitory peptides have shown potent ACE inhibitory activity with no side effects. In this study, we reported the discovery of a novel ACE-inhibitory peptide derived from trypsin hydrolysates of Cyclina sinensis (CSH). CSH was separated into four different molecular weight (MW) fractions by ultrafiltration. Fraction CSH-I showed the strongest ACE inhibitory activity. A peptide was purified by fast protein liquid chromatography (FPLC) and reversed-phase high-performance liquid chromatography (RP-HPLC) and its sequence was determined to be Trp-Pro-Met-Gly-Phe (WPMGF, 636.75 Da). The Lineweaver-Burk plot showed that WPMGF was a competitive inhibitor of ACE. WPMGF showed a significant degree of stability at varying temperatures, pH, and simulated gastrointestinal environment conditions. We investigated the interaction between this pentapeptide and ACE by means of a flexible molecular docking tool. The results revealed that effective interaction between WPMGF and ACE occurred mainly through hydrogen bonding, hydrophobic interactions, and coordination bonds between WPMGF and Zn(II). In conclusion, our study indicates that a purified extract derived from Cyclina sinensis or the WPMGF peptide could potentially be incorporated in antihypertensive functional foods or dietary supplements.
Assuntos
Inibidores da Enzima Conversora de Angiotensina/farmacologia , Anti-Hipertensivos/farmacologia , Organismos Aquáticos , Bivalves , Oligopeptídeos/farmacologia , Inibidores da Enzima Conversora de Angiotensina/química , Inibidores da Enzima Conversora de Angiotensina/isolamento & purificação , Animais , Anti-Hipertensivos/química , Anti-Hipertensivos/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Suplementos Nutricionais , Alimento Funcional , Simulação de Acoplamento Molecular , Oligopeptídeos/química , Oligopeptídeos/isolamento & purificação , Peptidil Dipeptidase A/química , Hidrolisados de Proteína/química , UltrafiltraçãoRESUMO
Pichia kudriavzevii YB5, mutated from Pichia kudriavzevii A16 with a strong ability to remove cadmium ions, was immobilized by polyurethane foam and alginate gels in this work. The immobilization conditions were optimized as follows: sodium alginate concentration of 2% (w/v), calcium chloride concentration of 2% (w/v), biomass dose of 1 × 109 cell/mL, and cross-linking time for 4 h. Then, the results of batch adsorption experiments showed that the removal capacity of prepared bioadsorbent was significantly affected by the pH of media, contact time, and the initial Cd(II) concentration, and a suitable adsorption conditions of Cd(II) could be achieved with a pH value of 6.0 at 20 °C for 90 min. Kinetic and isothermal results indicated the behavior of Cd(II) adsorption onto immobilized P. kudriavzevii YB5 fitted to the pseudo-second-order kinetic equation and the Langmuir adsorption model. Thermodynamic results showed that the Cd(II) adsorption process was endothermic and spontaneous in nature. Besides, the Cd(II) removing capacity of the prepared bioadsorbent was also tested in the oyster hydrolysates, showing an average removal rate of 54.35%. Thus, the immobilized P. kudriavzevii YB5 adsorbent had great potential for application in aquatic products to ensure the food safety.
Assuntos
Alginatos/química , Cádmio/metabolismo , Pichia/metabolismo , Poliuretanos/química , Poluentes Químicos da Água/metabolismo , Adsorção , Géis , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Íons/metabolismoRESUMO
As the most abundant carotenoid in nature, fucoxanthin is susceptible to oxidation under some conditions, forming cleavage products that possibly exhibit both positive and negative health effects in vitro and in vivo. Thus, to produce relatively high amounts of cleavage products, chemical oxidation of fucoxanthin was performed. Kinetic models for oxidation were probed and reaction products were identified. The results indicated that both potassium permanganate (KMnO4) and hypochlorous acid/hypochlorite (HClO/ClO(-)) treatment fitted a first-order kinetic model, while oxidation promoted by hydroxyl radical (OH) followed second-order kinetics. With the help of liquid chromatography-tandem mass spectrometry, a total of 14 apo-fucoxanthins were detected as predominant cleavage products, with structural and geometric isomers identified among them. Three apo-fucoxanthinones and eleven apo-fucoxanthinals, of which five were cis-apo-fucoxanthinals, were detected upon oxidation by the three oxidizing agents (KMnO4, HClO/ClO(-), and OH).
Assuntos
Espectrometria de Massas em Tandem/métodos , Undaria , Xantinas/análise , Xantinas/química , Xantofilas/análise , Xantofilas/química , Pressão Atmosférica , Carotenoides/análise , Carotenoides/química , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida/métodos , Undaria/químicaRESUMO
An efficient ultrasonic-assisted enzymatic extraction technique was applied to extracting phenolics from broccoli inflorescences without organic solvents. The synergistic model of enzymolysis and ultrasonication simultaneously was selected, and the enzyme combination was optimized by orthogonal test: cellulase 7.5 mg/g FW (fresh weight), pectinase 10 mg/g FW, and papain 1.0 mg/g FW. The operating parameters in ultrasonic-assisted enzymatic extraction were optimized with response surface methodology using Box-Behnken design. The optimal extraction conditions were as follows: ultrasonic power, 440 W; liquid to material ratio, 7.0:1 mL/g; pH value of 6.0 at 54.5 â for 10 min. Under these conditions, the extraction yield of phenolics achieved 1.816 ± 0.0187 mg gallic acid equivalents/gram FW. The free radical scavenging activity of ultrasonic-assisted enzymatic extraction extracts was determined by 1,1-diphenyl-2-picrylhydrazyl·assay with EC50 values of 0.25, and total antioxidant activity was determined by ferric reducing antioxidant power assay with ferric reducing antioxidant power value of 0.998 mmol FeSO4/g compared with the referential ascorbic acid of 1.184 mmol FeSO4/g.
Assuntos
Antioxidantes/análise , Brassica/química , Manipulação de Alimentos/métodos , Inflorescência/química , Fenóis/isolamento & purificação , Ultrassom , Antioxidantes/química , Compostos de Bifenilo/química , Celulase , Compostos Férricos/química , Sequestradores de Radicais Livres , Concentração de Íons de Hidrogênio , Oxirredução , Papaína , Fenóis/química , Picratos/química , Poligalacturonase , TemperaturaRESUMO
An efficient ultrasound-assisted enzymatic extraction (UAEE) of Cucurbita moschata polysaccharides (CMCP) was established and the CMCP antioxidant activities were studied. The UAEE operating parameters (extraction temperature, ultrasonic power, pH, and liquid-to-material ratio) were optimized using the central composite design (CCD) and the mass transfer kinetic study in UAEE procedure was used to select the optimal extraction time. Enzymolysis and ultrasonication that were simultaneously conducted was selected as the UAEE synergistic model and the optimum extraction conditions with a maximum polysaccharide yield of 4.33 ± 0.15% were as follows: extraction temperature, 51.5 °C; ultrasonic power, 440 W; pH, 5.0; liquid-to-material ratio, 5.70:1 mL/g; and extraction time, 20 min. Evaluation of the antioxidant activity in vitro suggested that CMCP has good potential as a natural antioxidant used in the food or medicine industry because of their high reducing power and positive radical scavenging activity for DPPH radical.