The zinc absorption of the novel peptide-Zn complex in Caco-2 cells: effects of soybean peptides charge and hydrophobicity.

BACKGROUND: The supplemental effect of zinc depends not only on adequate intake, but also on how efficiently it is absorbed in the small intestine. In the present study, weak hydrophobic peptides (WHP), strong hydrophobic peptides (SHP), positively charged peptides (PCP) and negatively charged peptides (NCP) were isolated from soybean peptides (SP). The peptide-Zn complexes (PCP-Zn, NCP-Zn, WHP-Zn, SHP-Zn and SP-Zn) were prepared to compare their promotion zinc absorption capacity in the Caco-2 cells monolayers model. RESULTS: We found that the carboxyl, carbonyl and amino groups in peptide were the primary binding sites of Zn. Compared with zinc sulfate, the peptide-Zn complexes with different charge and hydrophobic peptides could improve zinc solubility at different pH. NCP-Zn had a lower Zn-binding capacity but a higher zinc absorption capacity compared to that of PCP-Zn in Caco-2 cells. In addition, the capacity of PCP-Zn to promote zinc absorption was lower than the control group (SP-Zn). There were no significant differences in transport rates, retention rates and uptake rates of WHP-Zn, SHP-Zn and SP-Zn. NCP-Zn could improve the activity of Zn-related enzymes, and the expression levels of PepT1 and ZnT1 were higher than other peptide-Zn complexes. CONCLUSION: The promotion zinc absorption capacity of peptide-Zn complexes was not completely dependent on the Zn-binding capacity, but also depended on the charge and hydrophobicity of peptides. © 2024 Society of Chemical Industry.

Lychee pulp phenolics fermented by mixed lactic acid bacteria strains promote the metabolism of human gut microbiota fermentation in vitro.

Lychee pulp phenolics possess excellent biological activities, however, changes in phenolic substances after microbial treatments are unknown. Herein, lychee pulp was fermented by Lactobacillus plantarum, Lactobacillus rhamnosus, and a mixed strain of the two, followed by an investigation of the products' colonic fermentation. In comparison to single-strain fermentation, mixed-strain fermentation significantly increased catechin and quercetin. In addition, lychee phenolics fermented by mixed strains were more conducive to the growth of gut microbiota. The results of HPLC-DAD showed that colonic fermentation further promoted the release of lychee phenolics. There was a notable increase in the content of gallic acid and quercetin, while multiple phenolics were degraded. Quercetin-3-O-rutinose-7-O-α-L-rhamnoside (QRR) and rutin were catabolized into quercetin by gut microbiota, and 4-hydroxybenzoic acid was produced from the metabolism of QRR and procyanidin B2. Lychee phenolics fermented by mixed lactic acid bacteria were easily metabolized and transformed by gut microbiota. These findings indicate that lychee pulp fermented by mixed lactic acid bacteria possesses probiotic potential, which is of great significance for the development of functional probiotic products.

Divergent metabolism of two lychee (Litchi chinensis Sonn.) pulp flavonols and their modulatory effects on gut microbiota: Discovery of hydroxyethylation in vitro colonic fermentation.

Quercetin 3-O-rutinose-7-O-α-l-rhamnoside (QRR), a characteristic lychee pulp flavonoid, has been linked to diverse bioactivities involving microbial metabolism. By integrating colonic fermentation and mass spectrometry, the catabolites including 7-O-hydroxyethyl-isorhamnetin and 3'-amino-4'-O-methyl-7-O-hydroxyethyl-isorhamnetin were unprecedently identified and unique to QRR metabolism, relative to the structural analog quercetin 3-O-rutinoside (QR) metabolism. These above-described metabolites highlighted a special biotransformation hydroxyethylation in QRR catabolism. QRR was partially deglycosylated into quercetin 3-O-glucoside-7-O-α-l-rhamnoside potentially catalyzed by Bacteroides. QR was more directly degradable to aglycone during colonic fermentation than are QRR. Unlike with QR fermentation, equivalent QRR effectively upregulated concentrations of propionic and butyric acids that were highly relevant with Faecalibacterium and Coprococcus. After fermentation, the relative abundances of Bacteroides uniformis (0.03%) and Akkermansia muciniphila (0.13%) were only upregulated by QRR among all fermentation groups, leading to the enrichments of the corresponding genera. These results further reveal the relationship between flavonoid structures and metabolic characteristics.

Development, characterization and in vivo zinc absorption capacity of a novel soy meal hydrolysate-zinc complexes.

Background: Zinc is an essential trace element for the human body. Recently, a novel Zn-binding peptide, Lys-Tyr-Lys-Arg-Gln-Arg-Trp (PP), was purified and identified from soy protein hydrolysates with high Zn-binding capacity (83.21 ± 2.65%) by our previous study. The preparation of soy meal hydrolysates (SMHs)-Zn complexes is convenient and low-cost, while PP (Lys-Tyr-Lys-Arg-Gln-Arg-Trp)-Zn complexes have a higher coordination rate but a relatively high cost. The aim of this study was to investigate the effect of soy meal hydrolysates (SMHs)-Zn complexes on zinc absorption in mice model, and synthetic soy peptide (PP)-Zn complexes with high Zn-binding capacity were used as control. Firstly, SMHs were prepared by enzymolysis, and the PP (Lys-Tyr-Lys-Arg-Gln-Arg-Trp) were synthesized based on previous studies. The binding mechanism of soy hydrolysates and zinc was analyzed by spectral analysis. Furthermore, the cytotoxicity of the SMHs-Zn complexes was also studied using the CCK-8 method. The effect of zinc absorption was evaluated based on Zn content, total protein and albumin content, relevant enzyme system, and the PeT1 and ZnT1 mRNA expression levels. Result: The result showed that zinc was bound with carboxyl oxygen and amino nitrogen atoms on SMHs, with hydrophobic and electrostatic interactions as auxiliary stabilizing forces. SMHs-Zn were proved to have great solubility and a small particle size at different pH values, and it showed a beneficial effect on Caco-2 cells growth. Moreover, it was proved that SMHs-Zn and PP-Zn could increase the levels of zinc and the activity of Zn-related enzymes in mice. SMHs-Zn possessed higher PepT1 and ZnT1 mRNA expression levels than PP-Zn in the small intestine. Conclusion: SMHs-Zn with a lower Zn-binding capacity had similar effects on zinc absorption in mice as PP-Zn, suggesting that the bioavailability of peptide-zinc complexes in mice was not completely dependent on their Zn-binding capacity, but may also be related to the amino acid composition.

Magnetic nanometer combined with microwave: Novel rapid thawing promotes phenolics release in frozen-storage lychee.

Magnetic nanometer combined with microwave thawing (MN-MT) could become a novel solution to challenges uneven and overheating of microwave thawing (MT), while retaining high thawing efficiency, compared to conventional water immersion thawing (WT). In this study, MN-MT was applied to thaw fruit (lychee as an example) for the first time, and was evaluated by comparison with WT, MT and water immersion combined with microwave thawing (WI-MT). Results showed that MN-MT could significantly shorten the thawing time of frozen lychee by 80.67%, 25.86% and 18.83% compared to WT, MT and WI-MT, respectively. Compared to WT, MN-MT was the only thawing treatment which significantly enhanced the release of quercetin-3-O-rutinose-7-O-α-l-rhamnoside, according to HPLC-DAD. Meanwhile, thermal-sensitive procyanidin B2, phenylpropionic acid and protocatechuic acid were found to be protected from degradations only by MN-MT based on UPLC-ESI-QTOF-MS/MS results. In summary, MN-MT is a potential novel treatment for rapid thawing and quality maintenance of frozen fruits.

Fabrication of food grade zein-dispersed selenium dual-nanoparticles with controllable size, cell friendliness and oral bioavailability.

In this study, novel bioavailable selenium nanoparticles with controllable particle size and low toxicity were developed. With selenium modified zein nanoparticles (zein NPs) in-situ, dispersed nano-selenium particles with different structure were formed simultaneously. The particle size, zeta potential, morphology and binding mechanism of synthesized zein-selenium nanoparticles (zein-Se NPs) were systematically discussed. Selenium was considered to be combined with OH and -CO-NH- groups of zein. The selenium in the complex particles presented an amorphous structure with zero valence. The cytotoxicity of zein-Se NPs was significantly lower than that of sodium selenite, even exhibited a growth-promoting effect on normal liver cells (L-02), and were proven to be orally absorbed by organisms in vivo experiments. The difference in particle structure had certain effects on cytotoxicity and oral targeting. The complex particles obtained by this method were anticipated be further used as food fortifiers or medicines.

A novel zein-selenium complex nanoparticle with controllable size: Quantitative design, physical properties and cytotoxicity in vitro.

In this study, after proposing a method for the preparation of selenium nanoparticles (Se NPs) with stable properties using zein, the physico-chemical properties of zein-Se NPs were tested. The complex structure of zein-Se NPs was deduced by SEM, and the binding mechanism was determined by FT-IR and XPS. The particle size of zein-Se NPs could be regulated from 11.4 ± 0.1 nm to 138.7 ± 0.9 nm under different preparation parameters, the reason for the change in particle size had been speculated. The pH responsiveness and 30-day storage stability of the zein-Se NPs were discussed. The zein-Se NPs still had strong DPPH radical scavenging activity after heat treatment. The zein-Se NPs were cell-friendly and was able to effectively protect cells from H2O2-induced cell-death. This study performed an extensive determination of the underlying physico-chemical properties of zein-Se NPs, we anticipate this approach will open up new possibilities in using natural material to stabilize Se NPs.

Alteration in dough volume and gluten network of lychee pulp pomace bread base on mixture design dominated by particle size.

The reducing flavor of whole grain bread has been constantly affecting the consumption desire of a significant proportion of consumers. The study presents the use of lychee pulp pomace (LPP) powder to replace certain proportion of wheat flour and produce wheat bread with better quality, while having minimal effects on the volume and improving the nutritional quality. Distinct particle sizes (60-400 µm) of LPP powder were obtained by superfine or ordinary grinding. Effect of different additive proportions (7-19%) of LPP powder on bread dough quality were studied by constrained mixture designs. The volume of fermented doughs subsequently decreased after adding LPP powder. However, LPP powders with smaller particle sizes were able to minimize this effect due to its higher water-holding capacity. The analyses of gluten network showed that smaller particle sizes of LPP powder resulted in a decrease in surface hydrophobicity and increase in the elasticity and stability of gluten network. Finally, optimum mixture formula was composed of 16% LPP powder with 60 µm particle size and 15% water. The study illustrated the potential to make high-quality bread with small particle size of LPP powder. PRACTICAL APPLICATION: The addition of dietary fiber to wheat flour can adversely affect the dough volume and reduce the dough quality. By reducing the particle size of lychee pulp pomace powder, this adverse effect could be minimized while increasing the content of dietary fiber and bound phenolics in the dough. This provides data for the production of high-quality lychee dough bread.

Development, characterization and in vitro bile salts binding capacity of selenium nanoparticles stabilized by soybean polypeptides.

The paper presents the positive effect of soybean polypeptides (SP) on the stability and the potential hypolipidemic effect of selenium nanoparticles (SeNPs). After preparing SeNPs, SP with different molecular weight were introduced to stabilize SeNPs. We found that the SP with molecular weight >10 kDa (SP5) had the best stabilizing effect on SeNPs. We inferred that the steric resistance resulting from the long chains of SP5 protected SeNPs from collision-mediated aggregation, and the electrostatic repulsions between SP5 and SeNPs also played a positive role in stabilizing SeNPs. The as-prepared SP5-SeNPs were spherical, amorphous and zero valent. It was proved that SeNPs were bound with SP5 through O- and N- groups in SP5, and the main forces were hydrogen bonds and van der Waals forces. The bile salts binding assay showed that the SP5-SeNPs exhibited a high binding capacity to bile salts, which indicated their potential in hypolipidemic application.

Synthesis, characterization of tuna polypeptide selenium nanoparticle, and its immunomodulatory and antioxidant effects in vivo.

The tuna polypeptide (TP) was used as the reducing agent and the stabilizing agent to synthesize a tuna polypeptide selenium nanoparticle (TP-SeNP) via a green method. An animal experiment was conducted to investigate its immunomodulatory and antioxidant effects in vivo. The results indicated that the TP regulated the accumulation and stabilization of the TP-SeNP. And the conversion of selenium was tested to be 20.44%. The TP-SeNP was about 22 nm in diameter, a mix of spherical and quasi-spherical, and amorphous. The reaction between the TP and Na2SeO3 was entropy-driven spontaneous, and the binding force was mainly hydrophobic. Intake of the TP-SeNP could greatly increase the phagocytic activity of the mononuclear phagocytic system, and the contents of immunological molecules. The antioxidant capacity of the liver was also improved.

Microgel-Stabilized Hydroxypropyl Methylcellulose and Dextran Water-in-Water Emulsion: Influence of pH, Ionic Strength, and Temperature.

A stable water-in-water (W/W) emulsion was formed by mixing dextran and hydroxypropyl methylcellulose (HPMC) with addition of ß-lactoglobulin (Blg) microgels. The microstructure and stability of the W/W emulsion were investigated under different conditions. The microgels accumulating at the liquid-liquid interface led to a stable emulsion at pH 3-5, where the microgels carried positive charges. When the pH was increased above the pI of microgels (∼pH 5), the emulsion was destabilized because the microgels tended to stay in the continuous phase (i.e., dextran) rather than at the interface. The HPMC-in-dextran emulsions were stable under ionic strength levels up to 300 mM. The HPMC-in-dextran emulsion stabilized by Blg microgels was thermally stable, and the heat treatment promoted partial Blg microgel particle-particle fusion on the surface of HPMC droplets at 90 °C. Electrostatic and hydrophobic interactions between dextran and HPMC phase were further investigated to understand the microgels' accumulation at the liquid-liquid interface.

Novel Zn-Binding Peptide Isolated from Soy Protein Hydrolysates: Purification, Structure, and Digestion.

In this study, a novel Zn-binding peptide, Lys-Tyr-Lys-Arg-Gln-Arg-Trp (KYKRQRW), was purified and identified from soy protein isolate hydrolysates (SPIHs). The Zn-binding peptide exhibited improved Zn-binding capacity (83.21 ± 2.65%) than SPIH solutions. CD, NMR, and Fourier transform infrared spectroscopy were used to confirm the complexation between Zn and the peptide. The results showed that the Zn-binding peptide formed a folding structure with part of the ß-sheet (29.3-13.4%) turning into random coils (41.7-57.6%) during complexation. It was further proved that the binding sites were located at the oxygen atoms on the carboxyl group of the Trp side chain and nitrogen atoms on the amino group of the Lys side chain. Moreover, the Zn-peptide complex exhibited increased solubility than ZnSO4 during simulated gastrointestinal digestion. This study highlighted that the novel soy peptide possessed a strong zinc chelate rate and had a positive effect on the gastrointestinal stability of Zn which could be utilized as a functional ingredient in future.

Comparative analysis of the morphological property and chemical composition of soluble and insoluble dietary fiber with bound phenolic compounds from different algae.

The morphological, physicochemical, and biochemical properties of soluble and insoluble dietary fiber from seven types of algae were investigated. The soluble dietary fiber (SDF) contents (6.48 to 60.90% of the total fiber) in most of the investigated algae were significantly lower than the insoluble dietary fiber (IDF) contents (39.10 to 93.52% of the total fiber). It can be inferred from the infrared and UV-Vis spectra that the SDF and IDF of algae may contain cellulose, hemicellulose, various monosaccharides, phenolic compounds, and quinone pigments. The bound phenolic in the seven algae varied widely in contents (3.76 to 14.08 mg GAE/g in IDF and 1.94 to 8.61 mg GAE/g in SDF), whose antioxidant activities in the IDF were stronger than those in SDF because of different phenolic compositions. The HPLC-mass spectrometry (MS)/MS results showed that the IDF may contain methyl-8α-hydroxy-grindelate-7ß-O-7'ß-ether hydrate, hydroxydecanoic acid, and malyngic acid. PRACTICAL APPLICATION: Polysaccharides of high content in algae cannot be digested by humans, hence regarded as dietary fibers. A large amount of bound phenolic compounds in dietary fibers can add to the biological activities of dietary fibers. These topics are important to the development of seaweed-based functional foods.

Antioxidative activity of oyster protein hydrolysates Maillard reaction products.

A two-step process of enzymatic hydrolyzation followed by Maillard reaction was used to produce oyster meat hydrolysate Maillard reaction products (MRPs). The flavor of oyster meat hydrolysate MRPs was significantly improved through an optimized orthogonal experimental design. Comparisons between the antioxidative activities of oyster meat hydrolysates and their MRPs were made using lipid peroxidation inhabitation, hydroxyl radical scavenging radical activity, and radical scavenging activity of 2,2 diphenyl-1-picrylhydrazyl (DPPH). These methods indicated that an improvement of Maillard reaction on the oyster meat hydrolysates antioxidative activity. Gas chromatography-mass spectrometry illustrated that the increase was due to the newly formed antioxidative compounds after Maillard reaction, mainly of acids from 22.45% to 37.77% and phenols from 0% to 9.88%.

Effects of simulated digestion on the phenolic composition and antioxidant activity of different cultivars of lychee pericarp.

BACKGROUND: Lychee pericarp is rich in phenolic and has good antioxidant activity. The effects of simulated gastric (SGF) and intestinal fluid (SIF) digestion on the contents, composition, and antioxidant activities of the phenolic substances in the pericarp of different lychee cultivars (cv Jizui, Lizhiwang, Guiwei, Yuhe, Nuomici and Guihong) were investigated. RESULTS: Compared with distilled water (DW) treatment, the total phenolic content (TPC) and total flavonoid content (TFC) in the pericarp of different lychee cultivars decreased after SGF digestion; especially, the TFC in "Lizhiwang" decreased by 41.5%. The TPC and TFC of lychee pericarp also decreased after SIF digestion. However, the TPC in "Jizui", "Guiwei" and "Yuhe" increased. The SGF and SIF also had different effects on the FRAP and ABTS antioxidant activities of different lychee cultivars. The SGF digestion decreased the ABTS antioxidant capacity of lychee pericarp but enhanced the FRAP value of some lychee cultivars. However, the SIF digestion decreased the FRAP antioxidant activity of different lychee cultivar pericarps but enhanced the ABTS antioxidant capacity of lychee. The HPLC results showed that lychee pericarp had relatively high contents of procyanidin B2 and procyanidin A2. After SIF digestion, caffeic acid and isoquercitrin could not be detected in any of the lychee varieties. However, quercetin-3-rutinose-7-rhamnoside and isoquercitrin were increased after SGF digestion. CONCLUSIONS: Lychee pericarp could be used as an inexpensive functional food ingredient.

Significant fat reduction in deep-fried kamaboko by fish protein hydrolysates derived from common carp (Cyprinus carpio).

BACKGROUND: To evaluate their fat reduction effect, common carp fish protein hydrolysates (FPH) were made using four methods: the conventional enzymatic process, a microwave-intensified enzymatic process, the conventional alkaline hydrolysis process, and a microwave-intensified alkaline hydrolysis process. RESULTS: The efficiency of protein extraction was significantly enhanced by microwave intensification. The oil-holding capacities of FPH produced by these four processes were all lower than that of raw fish protein. The water-holding capacities of FPH produced by these four processes were all higher than that of raw fish protein. The FPH from the four processes and raw fish protein were used in the preparation of deep-fried kamaboko. The fat content of deep-fried kamaboko was drastically reduced from approximately 160 g kg-1 to about 50 g kg-1 by replacing 20 g kg-1 fish mince with FPH, regardless of the process. Texture profile analysis (TPA) of deep-fried kamaboko found no significant difference in hardness and brittleness among all the deep-fried kamaboko samples. The similar interior protein cross-linking micro-structure of all these samples further explained the TPA finding. CONCLUSION: With the involvement of FPH in the formulation, the fat content of deep-fried kamaboko can be significantly reduced from approximately 160 to 50 g kg-1 , without a change in its texture. © 2018 Society of Chemical Industry.

Marine microalgae bioengineered Schizochytrium sp. meal hydrolysates inhibits acute inflammation.

Bioengineered marine microalgae Schizochytrium sp. is currently used to produce docosahexaenoic acid (DHA). However, following DHA extraction, the remaining protein-rich materials are not well utilized. In this study, we report that marine microalgae bioengineered Schizochytrium sp. hydrolysate (MESH), which exhibits a unique peptide profile as identified by Ultra Performance Liquid Chromatography coupled with Q-TOF mass spectrometry(UPLC/Q-TOF-MS), ameliorated bowel inflammation in mice. In a mouse model of experimentalcolitis induced by dextran sulfate sodium, compared with the control mice, the mice treated with MESH were highly resistant to colitis, as demonstrated by marked reductions in body weight loss, clinical colitis scores, colonic histological damage, and colonic inflammation. Mechanistically, MESH attenuated the induction of pro-inflammatory cytokines and increased the induction of anti-inflammatory cytokines. MESH also promoted the proliferation of colonic crypt stem cells and progenitor cells required for crypt repair. Collectively, these results reveal a previously unrecognized role of MESH as a potential anti-inflammatory treatment for colitis.

The formation of zein-chitosan complex coacervated particles: Relationship to encapsulation and controlled release properties.

The complex coacervation between zein and chitosan (CS) as well as the relationship with the controlled release properties of their complex nanoparticles were studied. The factors influencing the nanoparticle formation between zein and CS, including solid to liquid ratio, zein to CS ratio and pH, were systematically investigated. The isothermal titration calorimetry (ITC) showed that zein-CS interaction was spontaneous exothermic process. The pH the higher was, the stronger the interaction between zein and CS. The mean particle sizes of ZCNPs were increased by enhanced turbidity between zein and CS (from 90.89 nm to 1368.77 nm). The morphology study showed that spherical particles and coacervate were obtained with the increased interaction between zein and CS. The release profiles of curcumin in vitro indicated that slight burst effect followed by slow release was observed after interacting CS. The ZCNPs at pH 4.0 exhibited smaller particle size (162.07 nm), more stable ζ-potential (49.7 mV), higher encapsulation efficiency (94.67%) and slower release rate. In conclusion, the stronger the interaction was, the lower the curcumin released from the nanoparticles in vitro, and the ZCNPs at pH 4.0 had better potential in oral delivery application.

Development, physicochemical characterization and cytotoxicity of selenium nanoparticles stabilized by beta-lactoglobulin.

Novel Selenium nanoparticles (SeNPs) were developed using beta-lactoglobulin (Blg) as a stabilizer in redox systems of selenite and ascorbic acid in this study. Particle size, morphology, stability, and in vitro biological activity of synthesized Blg stabilized selenium nanoparticles (Blg-SeNPs) were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), ultraviolet-visible spectrophotometry (UV/Vis), and cell toxicity assays, respectively. Stabilizing mechanisms of Blg-SeNPs were investigated by Fourier-transform infrared spectroscopy (FTIR) and protein fluorescence probe. The results revealed that the Blg-SeNPs were spherical with mean particle size of 36.8±4.1nm. They were stable in acidic or neutral to basic solutions (pH 2.5-3.5 or 6.5-8.5) at 4°C for 30days as a result of electrostatic repulsions. FTIR results showed that functional groups of NH2 and OH on Blg molecules were responsible for binding with SeNPs. Furthermore, decreases in protein surface hydrophobicity indicated that possible binding happened between Se and the hydrophobic domains of Blg. The cell toxicity of Blg-SeNPs was significantly lower than that of sodium selenite on both cancerous and non-cancerous cells. This study provides a facile and green method for chemically synthesizing stable SeNPs which are suitable for further evaluation in medicinal applications.

Structural characterization and dissolution profile of mycophenolic acid cocrystals.

Three novel cocrystals of mycophenolic acid (MPA) with isonicotinamide (MPA-ISO), minoxidil (MPA-MIN) and 2,2'-dipyridylamine (MPA-DPA) as coformers have been prepared successfully by both slow evaporation and liquid-assisted grinding. The structures of these cocrystals show that all the three coformers form hydrogen bonds with the carboxylic acid group of MPA. The cocrystal MPA-ISO possesses remarkably improved solubility and dissolution rate, while two other cocrystals exhibit the opposite characteristics. The solids in the slurry with pH6.8 phosphate buffer and cocrystals remain as the incipient cocrystal after 24h. However, evidence of slight polymerization was shown in the slurry of pH6.8 phosphate buffer with MPA and MPA-ISO cocrystal.