Mechanism of the Allergenicity Reduction of Ovalbumin by Microwave Pretreatment-Assisted Enzymolysis through Biological Mass Spectrometry.

Ovalbumin (OVA) is a major allergen in hen eggs. Enzymolysis has been demonstrated as an efficient method for reducing OVA allergenicity. This study demonstrates that microwave pretreatment (MP) at 400 W for 20 s assisting bromelain enzymolysis further decreases the allergenicity of OVA, which was attributed to the increase in the degree of hydrolysis and promoted the destruction of IgE-binding epitopes. The results showed that MP could promote OVA unfolding, expose hydrophobic domains, and disrupt tightly packed α-helical structures and disulfide bonds, which increased the degree of hydrolysis by 7.28% and the contents of peptides below 1 kDa from 43.55 to 85.06% in hydrolysates compared with that for untreated OVA. Biological mass spectrometry demonstrated that the number of intact IgE-binding epitope peptides in MP-assisted OVA hydrolysates decreased by 533 compared to that in hydrolysis without MP; consequently, their IgG/IgE binding rates decreased more significantly. Therefore, MP-assisted enzymolysis may provide an alternative method for decreasing the OVA allergenicity.

Mitigation of Paeoniae Radix Alba extracts on H2O2-induced oxidative damage in HepG2 cells and hyperglycemia in zebrafish, and identification of phytochemical constituents.

Paeoniae Radix Alba (PRA), as a Traditional Chinese Medicine, is widely used in Chinese cuisine due to high health-benefits and nutrition, but the effect of different polarity of solvents on the extraction of antioxidant and hypoglycemic constituents, as well as the major active compounds remain unclear. In this research, 40, 70, and 95% ethanol were firstly applied to extract the polyphenols from PRA, the extraction yields, total phenolics, and total flavonoids content, free radical scavenging ability, α-glucosidase inhibition ability, and anti-glycation ability of extracts were evaluated spectroscopically. The oxidative damage protection, hypoglycemic activity, and alleviation on peripheral nerve damage were evaluated by H2O2-induced HepG2 cells and hyperglycemic zebrafish models. UPLC-QTOF-MS/MS was used to identify the major chemical constituents. The results showed that 40, 70, and 95% ethanol exhibited insignificant difference on the extraction of phenolics and flavonoids from PRA. All extracts showed promising DPPH⋅ and ABTS⋅+ scavenging ability, α-glucosidase inhibition and anti-glycation ability. In addition, PRA extracts could restore the survival rate of HepG2 cells induced by H2O2, and alleviate the oxidative stress by reducing the content of MDA and increasing the levels of SOD, CAT, and GSH-Px. The 70% ethanol extract could also mitigate the blood glucose level and peripheral motor nerve damage of hyperglycemic zebrafish. Thirty-five compounds were identified from 70% ethanol extract, gallotannins, gallic acid and its derivatives, and paeoniflorin and its derivatives were the dominant bioactive compounds. Above results could provide important information for the value-added application of PRA in functional food and medicinal industry.

Extraction optimization and identification of four advanced glycation-end products inhibitors from lotus leaves and interaction mechanism analysis.

Previous research indicated lotus leaves extract could effectively inhibit advanced glycation end-products (AGEs) formation, but the optimal extraction condition, bio-active compounds and interaction mechanism remain unclear. The current study was designed to optimize the extraction parameters of AGEs inhibitors from lotus leaves by bio-activity-guided approach. The bio-active compounds were enriched and identified, the interaction mechanisms of inhibitors with ovalbumin (OVA) were investigated by fluorescence spectroscopy and molecular docking. The optimum extraction parameters were solid-liquid ratio of 1:30, ethanol concentration of 70 %, ultrasonic time of 40 min, temperature of 50 °C, and power of 400 W. Isoquercitrin, hyperoside, astragalin, and trifolin were identified from the 80 % ethanol fraction of lotus leaves (80HY). Hyperoside and isoquercitrin were dominant AGEs inhibitors and accounted for 55.97 % of 80HY. Isoquercitrin, hyperoside, trifolin interacted with OVA via the same mechanism, hyperoside exhibited the strongest affinity, trifolin caused the most conformational changes.

The influence of in vitro gastrointestinal digestion on the Perilla frutescens leaf extract: Changes in the active compounds and bioactivities.

In this study, the influence of in vitro gastrointestinal digestion on the Perilla frutescens leaf extract (PFLE) were measured. Results revealed that total phenolic content (TPC) and total flavonoid content (TFC) were significantly decreased after simulated digestion (ca. 53% of phenolics and 40% of flavonoids). The IC50 value of DPPH· scavenging activity and ABTS+ scavenging ability increased by 23% and 56%, respectively, while ferric reducing antioxidant power reduced by 53%. For the inhibition ability on α-glucosidase, acetylcholinesterase, and MCF-7 cell proliferation, their IC50 values increased by 360%, 197%, and 25%, respectively. Three phenolic acids and one flavonoid in PFLE were quantified by high-performance liquid chromatography. Overall, although significant losses of the active components and biological activities occurred during in vitro gastrointestinal digestion, it still showed the potential as an oral agent for treatment and prevention of oxidative stress, cancer, diabetes, and Alzheimer's disease. PRACTICAL APPLICATIONS: As an important annual herbaceous plant with rich biochemical compounds and many biological functions, Perilla frutescens leave is widely used in the food and traditional Chinese medicine. However, the dynamic changes of its active compounds and activities during the digestion process are unclear. In this study, the digestion results in significant loss of the active ingredients and biological activities of P. frutescens leaf extract (PFLE), particularly in the gastric digestion. In addition, PFLE remains to show certain antioxidant activity, α-glucosidase inhibitory ability, acetylcholinesterase inhibitory ability, and MCF-7 cell proliferation inhibitory ability after digestion. Therefore, this research might facilitate further research and development of P. frutescens.

Mechanism of Selenium Nanoparticles Inhibiting Advanced Glycation End Products.

Selenium nanoparticles (SeNPs) have been applied in fields of nanobiosensors, environment, nanomedicine, etc. as a result of their excellent characteristics. Early studies had shown that SeNPs have certain inhibition ability against glycation, but the inhibition mechanism, especially for the influence of SeNPs on the reaction activity of glycation sites, remains unclear. The aim of the presented research was to reveal the effects of SeNPs on the ß-lactoglobulin (ß-Lg)/d-ribose glycation system at the molecular level and explore the possible inhibitory mechanism of SeNPs on the formation of advanced glycation end products (AGEs) by analyzing the glycation sites via high-performance liquid chromatography (HPLC)-Orbitrap-tandem mass spectrometry (MS/MS). Changes in contents of AGE formation and free amino acid contents had indicated that SeNPs could significantly slow the glycation process, thus attenuating the formation of AGEs. HPLC-Orbitrap-MS/MS analysis revealed that, at 6, 12, and 24 h, the number of glycation sites of glycated ß-Lg decreased from 7, 7, and 9 to 5, 5, and 6 after the intervention of SeNPs, respectively. The glycation extent of each glycation site was controlled, and the dual-glycation ability of K8, K14, K47, K91, and K101 was changed. All of these results confirmed that SeNPs could indeed slow the process of protein glycation at the molecular level. This may be the reason for SeNPs reducing the formation of AGEs during glycation. Therefore, this study shed light on the insight of how SeNPs reduce the formation of AGEs.

Antioxidant, metabolic enzymes inhibitory ability of Torreya grandis kernels, and phytochemical profiling identified by HPLC-QTOF-MS/MS.

In this study, the antioxidant activities, α-glucosidase and tyrosinase inhibitory ability of Torreya grandis kernels (TGK) were performed. Samples were extracted with various polarity of ethanol, and the major phytochemical profile was characterized. The results showed that 70% of ethanol extract gave the richest phenolics and flavonoids. The strongest DPPH· and ABTS·+ scavenging ability, as well as the best inhibition on tyrosinase and α-glucosidase was also detected on 70% of ethanol extract. Among the fractions of 70% of ethanol extract, the ethyl acetate fraction (EAF) owned the highest phenolics, flavonoids, and the best DPPH· and ABTS·+ scavenging ability, and tyrosinase inhibition. Unexpectedly, the dichloromethane fraction possessed the strongest inhibition on α-glucosidase, which was much greater than that of acarbose. HPLC-QTOF-MS/MS analysis result to the characterization of 19 compounds from EAF. The results implied that TGK can be a potential source of natural antioxidants, α-glucosidase and tyrosinase inhibitors. Practical applications The kernels of T. grandis are one of the precious nuts in the world, and the extracts were advertised to show a variety of biological activities and pharmacological effects. However, researches on the phytochemical constituents and bioactivities are fewer. In this study, TGK was found to show good potency in antioxidant, α-glucosidase and tyrosinase inhibitory activities. The 70% ethanol is the best solvent for extracting above mentioned active components, and ethyl acetate can be the suitable enriching solvent. In addition, the predominant phytochemical compounds in EAF were characterized. Therefore, this research can help to the performance of further research and application of TGK in functional products.

Gelation kinetics and characterization of enzymatically enhanced fish scale gelatin-pectin coacervate.

BACKGROUND: Protein-polysaccharide complex coacervations have been considered extensively for the development of functional foods. The main problem of the complex coacervates is that they are highly unstable under different conditions and that cross-linking is necessary to stabilize them. In this study, the effects of pectin at different concentrations on the gel and structural properties of fish scale gelatin (FSG)-high methoxyl citrus pectin (HMP) coacervate enhanced by microbial transglutaminase (MTGase) were studied. RESULTS: The gelation rates and gel strength of the MTGase-enhanced FSG-HMP coacervate gels decreased with increasing HMP concentration. However, the enhanced coacervate gels exhibited better thermal behavior and mechanical properties compared with the original gels. Also, TG-P8 exhibited the highest melting point (27.15 ± 0.12 °C), gelation point (15.65 ± 0.01 °C) and stress (15.36 ± 0.48 kPa) as HMP was 8 g kg-1 . Particle size distribution, fluorescence emission and UV absorbance spectra indicated that MTGase and HMP could make FSG form large aggregates. Moreover, confocal laser scanning microscopy of treated coacervate gels showed a continuous protein phase at low HMP concentrations. CONCLUSION: FSG and HMP could form soluble coacervate, and MTGase could improve the thermal and mechanical properties of coacervate gels. © 2017 Society of Chemical Industry.

Jackfruit (Artocarpus heterophyllus Lam.) peel: A better source of antioxidants and a-glucosidase inhibitors than pulp, flake and seed, and phytochemical profile by HPLC-QTOF-MS/MS.

Jackfruit (Artocarpus heterophyllus Lam.) peel is an underutilized by-product in both, the production and processing of jackfruit. This research compared the antioxidant and hypoglycemic potential of jackfruit peel with jackfruit pulp, flake and seed for the first time. The phytochemical profile of peel extract was characterized with HPLC-QTOF-MS/MS. Results revealed that peel extract exhibited the highest total phenolic and total flavonoid content, and the phenolics was 4.65, 4.12 and 4.95 times higher than that of pulp, flake and seed extract, respectively. The strongest DPPH and ABTS+ scavenging ability, α-glucosidase inhibition were also found in peel extract, and the α-glucosidase inhibition was about 11.8-fold of that of acarbose. The HPLC-QTOF-MS/MS analysis led to the tentative identification of 53 compounds, prenylflavonoids, hydroxycinnamic acids and glycosides are the predominant bioactive compounds. Above results reveal promising potential of jackfruit peel as a new source of natural antioxidants and hypoglycemic agents.

Pectin and enzyme complex modified fish scales gelatin: Rheological behavior, gel properties and nanostructure.

The rheological behavior, gel properties and nanostructure of complex modified fish scales gelatin (FSG) by pectin and microbial transglutaminase (MTGase) were investigated. The findings suggested that MTGase and pectin have positive effect on the gelation point, melting point, apparent viscosity and gel properties of FSG. The highest values of gel strength and melting temperature could be observed at 0.8% (w/v) pectin. Nevertheless, at highest pectin concentration (1.6% w/v), the gel strength and melting temperature of complex modified gelatin gels decreased. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis revealed that MTGase catalyzed cross-links among soluble fish scales gelatin - pectin complexes, which could be responsible for the observed increase in rheological behavior, gel strength and melting temperature of modified complex gels.

[The Interaction of Oil Microcapsule Wall Materials between Whey Protein and Acacia].

The interaction between whey protein and acacia which were used as wall material was studied on the formation of the oils microcapsules by the FTIR Spectroscopy and Computer Aided Analysis. The results indicated that whey protein changed obviously in amide A and amide I by high pressured homogenization and spray-drying. The amide A moved from 3 406.5 cm(-1) to 3 425.4 cm(-1) which was possibly due to covalent cross-linking between whey protein and acacia. Furthermore the amide I moved from 1 648.6 cm(-1) to 1 654.7 cm(-1) for intramolecular hydrogen bonding of protein had been weaken. After Gaussian fitting on amide I , it was found that the content of secondary structure of α-helix content and ß-folding in whey protein reduced from 19.55% to 17.50% and from 30.59% to 25.63%, respectively. This suggests that protein intramolecular hydrogen bonding force was abated, resulting in abating the rigid structure of the protein molecules and enhancing of the toughness structure. The protein molecules showed some flexibility. The result of SDS-PAGE electrophoresis showed that whey protein--gum Arabic complexes produced covalent products in larger molecular weight. During the spray-drying process, covalent cross-linking produced between whey protein and gum Arabic which improved emulsifying activity of the complex whey protein and gum Arabic produced covalent cross-linking and improved the complex emulsifying activity. Observing the surface structure of the fish oil microcapsule by SEM, the compound of whey protein and acacia as wall material was proved better toughness, less micropore, and more compact structure.

Metabolic profiling of antioxidants constituents in Artemisia selengensis leaves.

This study aimed to evaluate the antioxidant potential of Artemisia selengensis Turcz (AST) leaves, a byproduct when processing AST stalk, and identify the antioxidant constituents by using HPLC-QTOF-MS(2). The total phenolics content (TPC), total flavonoids content (TFC) and antioxidant abilities of fractions resulted from the successively partition of chloroform, ethyl acetate and n-butanol were compared. Ethyl acetate fraction (EAF) exhibited the highest TFC (65.44 mg QuE/g fraction), n-butanol fraction (nBuF) showed the highest TPC (384.78 mg GAE/g fraction) and the best DPPH scavenging ability, ABTS(+) scavenging ability and reducing power. Totally, 57 compounds were identified or tentatively identified in nBuF and EAF, 40 of them were reported in AST for the first time. The major constituents in EAF were flavonoids, and the major constituents in nBuF were phenolic acids and organic acids. Thus, AST leaves might be a potential low-cost resource of natural antioxidants.

New Gallotannin and other Phytochemicals from Sycamore Maple (Acer pseudoplatanus) Leaves.

The maple (Acer) genus is a reported source of bioactive (poly)phenols, including gallotannins, but several of its members, such as the sycamore maple (A. pseudoplatanus), remain uninvestigated. Herein, thirty-nine compounds, including a new gallotannin, 1,2,3-tri-O-galloyl-6-O-(p-hydroxybenzoyl)-ß-D- glucopyranoside (1), and thirty-eight (2-39) known compounds, consisting of four gallotannins, one ellagitannin, thirteen flavonoids, eight hydroxycinnamic acids, ten benzoic acid derivatives, and two sesquiterpenoids, were isolated from sycamore maple leaves. Their structures were determined based on NMR and mass spectral analyses. The isolates were evaluated for α-glucosidase inhibitory and antioxidant activities. Among the isolates, the gallotannins were the most potent α-glucosidase inhibitors with thirteen-fold more potent activity compared with the clinical drug, acarbose (IC50 = 16-31 vs. 218 µM). Similarly, the gallotannins showed the highest antioxidant activities, followed by the other phenolic sub-classes, while the sesquiterpenoids were inactive.

Response surface optimization and physicochemical properties of polysaccharides from Nelumbo nucifera leaves.

Dynamic high pressure microfluidization (DHPM)-assisted extraction (DHPMAE) of lotus (Nelumbo nucifera) leaves polysaccharides (LLPs) was optimized by response surface methodology. The optimal extraction conditions were: liquid/solid ratio of 35:1 (v/m, mL/g), processing pressure of 180 MPa, processed two times, extraction temperature of 76°C, extraction time of 50 min. Under the optimal extraction conditions, DHPMAE produced a higher polysaccharides yield (6.31%) than leaching (2.95%). Scanning electron microscope (SEM) analysis revealed that DHPM could reduce the particles size and make the surface more unconsolidated. The LLPs prepared by both methods showed similar FT-IR spectrum, and were consisted of the same monosaccharides, including rhamnose, fucose, arabinose, xylose, mannose, glucose and galactose. The content of each monosaccharide in extracts, however, was quite different. The average molecular weight of LLPs prepared by DHPMAE is 550 kDa, smaller than 578 kDa obtained by leaching. The LLPs prepared by DHPMAE exhibited stronger DPPH scavenging ability (IC50 value of 0.38 mg/mL), HO scavenging ability (IC50 value of 0.61 mg/mL) and reducing power. Therefore, DHPMAE can be a promising alternative to traditional extraction techniques for polysaccharides from plants, and lotus leaves might be a potential resource of natural antioxidants.

Medium-chain fatty acid nanoliposomes for easy energy supply.

OBJECTIVE: Developing a nanoliposome delivery system for an easy energy supply of medium-chain fatty acids (MCFAs) to improve oral doses and bioavailability. METHODS: Bangham's method and high-pressure microfluidization were used to prepare MCFA liposomes. The easy energy-supply property of MCFA nanoliposomes was estimated by the anti-fatigue experiments of mice including a weight-loaded swimming test and its corresponding parameters (serum urea nitrogen, blood lactic acid, and hepatic glycogen). For comparison, nanoliposomes without MCFAs and MCFAs not entrapped in nanoliposomes were used throughout. RESULTS: Compared with crude MCFA liposomes according to Bangham's method, the MCFA nanoliposomes made by high-pressure microfluidization exhibited great advantages in their characteristics, with a small average diameter (76.2 ± 34.7 nm), narrow size distribution (polydispersity index 0.207), high ζ-potential (-50.51 mV), great entrapment efficiency (70.5%) and drug loading (9.4%), and good stability. The high-dose group and the MCFA group (680 mg/kg) showed a longer weight-loaded swimming time (104 ± 29 min, P = 0.087, and 108 ± 11 min, P = 0.047, respectively) and significantly higher hepatic glycogen (16.40 ± 1.45 mg/g, P < 0.001 and 17.27 ± 2.13 mg/g, P < 0.001, respectively) than the control group (59 ± 11 min and 8.79 ± 2.76 mg/g, respectively). Moreover, serum urea nitrogen (891.5 ± 113.4 mg/L, P = 0.024, and 876.6 ± 70.8 mg/L, P = 0.015, respectively) and blood lactic acid (6.05 ± 1.40 mmol/L, P = 0.001, and 5.95 ± 1.27 mmol/L, P < 0.001, respectively) in the high-dose group and the group with an equivalent MCFA dose were significantly lower than those in the control group (1153.6 ± 102.5 mg/L and 12.53 ± 1.86 mmol/L, respectively). CONCLUSION: Similar to MCFAs, MCFA nanoliposomes prepared by high-pressure microfluidization showed a strong easy energy-supply property, which suggested that MCFA nanoliposomes could be a potential drug candidate for an easy energy supply.