Effect of multi-mode sweep frequency ultrasound pretreatment on properties of the zeins and ACE inhibitory peptides activity of the hydrolysates

Purification, identification, and in silico screening of a multifunctional octapeptide from semen armeniacae glutelin-2 hydrolysates: restraining mechanisms to Keap1 and ACE, stability, and ferrous-transport efficiency

Introduction

Semen armeniacae is a traditional homologous material of medicine and food, but data on its multifunctional peptides are little.

Methods

In this study, semen armeniacae glutelin-2 was hydrolyzed by alcalase and trypsin assisted with ultrasound. Antihypertensive and antioxidant peptides with ferrous-binding activity were isolated, identified, and in silico screened from the hydrolysates, and the action mechanisms against Keap1 and angiotensin-I-converting enzyme (ACE), gastrointestinal stability, and ferrous-binding capacity were studied.

Results and discussion

After Sephadex G-15 isolation, electrospray ionization mass spectrometry, and AHTpin and Peptide Ranker database screening, a safe multifunctional octapeptide: Pro-Val-Asp-Phe-Ala-Gly-Phe-Tyr (PVDFAGFY), was obtained. The capacities of PVDFAGFY to restrain ACE, chelate ferrous ions, and quench hydroxyl radical were IC50:105.61 μmol/L, 11.67 mg/g, and 97.67%, respectively. PVDFAGFY restrained ACE via competitively linking to its catalytic (His383) and/or crucial binding sites (Gln281, Lys511, Tyr523, Tyr520, or Ala354), and it can inhibit the Keap1-Nrf2 interaction by binding to 6 residues of Keap1. Ferrous ions were primarily chelated by γ-hydroxyl, carboxyl, and/or amino groups of PVDFAGFY via ionic forces. Gastrointestinal hydrolysis did not decrease the capacity of PVDFAGFY to antioxidant and restrain ACE (p > 0.05). The ACE inhibition model and activity of PVDFAGFY were not altered by iron chelation; however, PVDFAGFY-ferrous chelate showed lower hydroxyl and ABTS radical quenching capacity and ferric reducing ability than PVDFAGFY (p < 0.05). The gastrointestinal stability and transmembrane absorption of ferrous ions were increased by PVDFAGFY (p < 0.05). Thus, PVDFAGFY may be exploited as ingredients of hypotensive, antioxidant, and/or iron supplementary agents, but in vivo antioxidant and hypotensive efficiencies need further study.

Gliadin hydrolysates nanoparticles improve the bioavailability and antioxidant activity of berberine

Berberine (BBR) is an alkaloid with multiple physiological activities, but its low bioavailability limits its effectiveness in vivo. This study developed soluble nano delivery carriers using gliadin hydrolysates (GLH) to enhance BBR's bioavailability. The research evaluated the encapsulation efficiency, stability, release characteristics, and antioxidant capacities of GLH-BBR nanoparticles (GLH-BBR NPs) both in vitro and in vivo. Results showed that at a 5:1 GLH-to-BBR mass ratio, the encapsulation efficiency reached 74.95 %. GLH-BBR NPs increased DPPH radical scavenging from 19.19 % to 40.28 % and ABTS radical scavenging from 4.26 % to 60.96 %, compared to BBR alone. In vitro tests showed that GLH-BBR NPs inhibited BBR release during gastric digestion and promoted sustained release in the intestine. In addition, GLH-BBR NPs enhanced BBR's bioavailability and in vivo antioxidant activity. These findings support the development of sustainable peptide byproducts for high-quality delivery platforms.

Study on the antioxidant and antiosteoporotic activities of the oyster peptides prepared by ultrasound-assisted enzymatic hydrolysis

In this study, the effects of ultrasound-assisted enzymatic hydrolysis on the production of antioxidant and antiosteoporotic peptides derived from oysters were investigated. Results showed that ultrasound-assisted enzymatic hydrolysis significantly enhanced the peptide content, free radical scavenging ability, and ferric reducing antioxidant power of total oyster protein hydrolysate (TOPH), with optimal results achieved at 200 W (TOPH-200). Correspondingly, ultrasound treatment at 200 W increased the exposure of hydrophobic regions, reduced α-helix content, and facilitated the generation of small molecular weight peptides in TOPH. In an H2O2-induced oxidative damage model of osteoblastic MC3T3-E1 cells, TOPH-200 significantly attenuated intracellular reactive oxygen species and improved mitochondrial membrane potential. Importantly, TOPH-200 effectively enhanced osteogenic cell proliferation, differentiation, and mineralization in H2O2-treated MC3T3-E1 cells. Additionally, two novel peptides, DSQLAPFRF and HFNPRL, were screened from the TOPH-200 using PeptideRanker and molecular docking. Further cell experiments indicated that both peptides exhibited potent antioxidant and antiosteoporotic activities in oxidatively damaged MC3T3-E1 cells. In summary, mild ultrasound-assisted enzymatic hydrolysis proved effective in producing bioactive peptides from oysters, and these newly identified peptides exhibit potential for osteoporosis prevention.

Marine peptides as potential anti-aging agents: Preparation, characterization, mechanisms of action, and future perspectives

Aging is a universal biological process characterized by a decline in physiological functions, leading to increased susceptibility to diseases. With global aging trends, understanding and mitigating the aging process is paramount. Recent studies highlight marine peptides as promising bioactive substances with potential anti-aging properties. This review critically examines the potential of marine peptides as novel food ingredients in anti-aging, exploring their sources, preparation methods, physicochemical properties, and the underlying mechanisms through which they impact the aging process. Marine peptides exhibit significant potential in targeting aging, extending lifespan, and enhancing healthspan. They act through mechanisms such as reducing oxidative stress and inflammation, modulating mitochondrial dysfunction, inducing autophagy, maintaining extracellular matrix homeostasis, and regulating longevity-related pathways. Despite challenges in stability, bioavailability, and scalability, marine peptides offer significant potential in health, nutraceuticals, and pharmaceuticals, warranting further research and development in anti-aging.

Identification of novel antifreeze peptides from yak skin gelatin ultrasound-assisted enzymatic hydrolysate

In this paper, a new type of antifreeze peptide was identified from the ultrasonic-assisted enzymolysis product of yak skin. First, the antifreeze peptides were obtained by ultrasonic-assisted enzymolysis of yak skin gelatin. The obtained peptides with 150 W ultrasound treatment could increase the survival rate of Lactobacillus plantarum from 16 % to 60 % after four freeze-thaw cycles. Then, the component with the highest antifreeze activity in the peptides' ultrafiltration product was analyzed by LC-MS/MS to obtain 961 peptides. After screening of antifreeze activity and physical properties, three antifreeze peptide sequences were obtained (S1: GERGGPGGPGPQ, S2: PGGAEGPGRDAQQP, S3: VAPPGAPKKEH). DSC analysis, Lactobacillus plantarum cryoprotection experiments and molecular docking showed that the S1 sequence had the best antifreeze activity. This study provides a new idea for the high-value utilization of yak by-products and a potential candidate for food antifreeze agents.

Fabrication and characterization of potato short amylose, zein, and pectin ternary composite particles stabilized pickering emulsions and their application on nuciferine delivery

Nuciferine exhibits properties such as reducing blood sugar and fat, however, it is hindered by its poor water solubility and low bioavailability. Pickering emulsions can efficiently encapsulate, protect and deliver active ingredients. In recent years, the use of biologically derived natural materials as emulsifiers to construct Pickering emulsions has become a research hotspot. This research utilized an enzymatic hydrolysis technique to produce short amylose. Subsequently, a ternary composite of short amylose (DBS), zein, and pectin (PEC) was formulated to stabilize Pickering emulsion, with the incorporation of nuciferine aiming to enhance the performance of lotus leaves in terms of both stability and bioavailability. The study revealed that varying amounts of DBS addition had a significant impact on the micromorphological structure and functional properties of DBS-Zein-PEC ternary composite particles. Specifically, the addition of 0.4 g of DBS led to a notable reduction in particle size to 735.2 nm and Zeta potential to -29.6 mV, creating a three-dimensional network with a closely packed lamellar structure. Optimal process conditions for preparing Pickering emulsion included a 3-minute homogenization time, rotation speed of 15000 rpm, and 5 % ternary composite particle addition. Under these conditions, O/W Pickering emulsion was successfully prepared, achieving a 90.5 % encapsulation rate for nuciferine. The resulting emulsion exhibited a minimum particle size of 4.09 μm, displayed good storage stability, resistance to salt ions and pH variations, viscous fluid characteristics, tolerance to oral and gastric environments, and slow release of nuciferine in the small intestine, thereby enhancing its bioavailability. These findings offer insights into the loading and delivery of nuciferine and serve as a technical guide for developing highly stable emulsion gel systems.

On the modification of plant proteins: Traditional methods and the Hofmeister effect

With increasing consumer health awareness and demand from some vegans, plant proteins have received a lot of attention. Plant proteins have many advantages over animal proteins. However, the application of plant proteins is limited by a number of factors and there is a need to improve their functional properties to enable a wider range of applications. This paper describes the advantages and disadvantages of traditional methods of modifying plant proteins and the appropriate timing for their use, and collates and describes a method with fewer applications in the food industry: the Hofmeister effect. It is extremely simple but efficient in some respects compared to traditional methods. The paper provides theoretical guidance for the further development of plant protein-based food products and a reference value basis for improving the functional properties of proteins to enhance their applications in the food industry, pharmaceuticals and other fields.

Preparation of housefly (Musca domestica) larvae protein hydrolysates: Influence of dual-sweeping-frequency ultrasound-assisted enzymatic hydrolysis on yield, antioxidative activity, functional and structural attributes

Dual-sweeping-frequency ultrasound (DSFU) was utilized in the preparation of polypeptides from housefly (Musca domestica) larvae protein (HLP). Results indicated that ultrasonication (20 ± 2/28 ± 2 kHz, 42 W/L, 25 min) significantly increased peptide yield and DPPH scavenging capacity by 8.25 % and 14.83 %, respectively. Solubility, foaming and emulsification properties of polypeptides were improved by 19.89 %, 33.33 % and 38.74 % over the control; along with notable reduction in particle size and increase in zeta potential. Tertiary structural changes of the sonicated hydrolysates were illustrated by UV and fluorescence spectra. FTIR showed that ultrasonication increased α-helix, β-turn, and random coil by 38.23 %, 46.35 % and 16.36 %, respectively, but decreased β-sheet by 48.03 %, indicating partial unfolding in HLP hydrolysate conformation and reduction in intermolecular interactions. The research results demonstrated that dual-sweeping-frequency ultrasonication has a great prospect in industry application for the purpose of improving enzymolysis efficiency and product quality for housefly larvae protein hydrolysates production.

Effects of fermentation with Lactiplantibacillus plantarum NCU116 on the antihypertensive activity and protein structure of black sesame seed

Effects of fermentation by Lactobacillus Plantarum NCU116 on the antihypertensive potential of black sesame seed (BSS) and structure characteristics of fermented black sesame seed protein (FBSSP) were investigated. Angiotensin-I-converting enzyme (ACE) inhibition and zinc chelating ability of fermented black sesame seed hydrolysate (FBSSH) reached the highest of 60.78 ± 3.67 % and 2.93 ± 0.04 mg/mL at 48 h and 60 h of fermentation, respectively. Additionally, the antioxidant activities of FBSSH and surface hydrophobicity of FBSSP were increased noticeably by fermentation. The α-helix and β-rotation of FBSSP tended to decrease and increase, respectively, during fermentation. Correlation analysis indicated strong positive relationships between β-turn and ACE inhibition activity as well as zinc chelating ability with correlation coefficients r of 0.8976 and 0.8932. Importantly, novel ACE inhibitory peptides LLLPYY (IC50 = 12.20 μM) and ALIPSF (IC50 = 558.99 μM) were screened from FBSSH at 48 h using in silico method. Both peptides showed high antioxidant activities in vitro. Molecular docking analysis demonstrated that the hydrogen bond connected with zinc ions of ACE mainly attributed to the potent ACE inhibitory activity of LLLPYY. The findings indicated that fermentation by Lactobacillus Plantarum NCU116 is an effective method to enhance the antihypertensive potential of BSS.

Effects of sound energy on proteins and their complexes

Mechanical energy in the form of ultrasound and protein complexes intuitively have been considered as two distinct unrelated topics. However, in the past few years, increasingly more attention has been paid to the ability of ultrasound to induce chemical modifications on protein molecules that further change protein-protein interaction and protein self-assembling behavior. Despite efforts to decipher the exact structure and the behavior-modifying effects of ultrasound on proteins, our current understanding of these aspects remains limited. The limitation arises from the complexity of both phenomena. Ultrasound produces multiple chemical, mechanical, and thermal effects in aqueous media. Proteins are dynamic molecules with diverse complexation mechanisms. This review provides an exhaustive analysis of the progress made in better understanding the role of ultrasound in protein complexation. It describes in detail how ultrasound affects an aqueous environment and the impact of each effect separately and when combined with the protein structure and fold, the protein-protein interaction, and finally the protein self-assembly. It specifically focuses on modifying role of ultrasound in amyloid self-assembly, where the latter is associated with multiple neurodegenerative disorders.

Effect of High-Hydrostatic-Pressure Treatment on the Physicochemical Properties of Kafirin

The kafirin derived from Jin Nuo 3 sorghum underwent a high-hydrostatic-pressure (HHP) treatment of 100, 300, and 600 MPa for 10 min to investigate alterations in its physicochemical attributes. The findings exhibited a reduction in protein solubility, declining from 83% to 62%, consequent to the application of the HHP treatment. However, this treatment did not lead to subunit-specific aggregation. The absorption intensity of UV light diminished, and the peak fluorescence absorption wavelength exhibited a shift from 342 nm to 344 nm, indicating an increased polarity within the amino acid microenvironment. In an aqueous solution, the specific surface area expanded from 294.2 m2/kg to 304.5 m2/kg, while the average particle-size value in a 70% ethanol solution rose to 26.3 nm. Conversely, the zeta-potential value decreased from 3.4 mV to 1.3 mV, suggesting a propensity for aggregation in ethanol solutions. A notable rise in the intermolecular β-sheet content to 21.06% was observed, along with a shift in the peak denaturation temperature from 76.33 °C to 86.33 °C. Additionally, the content of disulfide bonds increased to 14.5 μmol/g. Collectively, the application of the HHP treatment not only enhanced the thermal stability but also induced a more ordered secondary structure within the kafirin.

Ultrasound-Assisted Enzymatic Protein Hydrolysis in Food Processing: Mechanism and Parameters

Ultrasound has been widely used as a green and efficient non-thermal processing technique to assist with enzymatic hydrolysis. Compared with traditional enzymatic hydrolysis, ultrasonic-pretreatment-assisted enzymatic hydrolysis can significantly improve the efficiency of enzymatic hydrolysis and enhance the biological activity of substrates. At present, this technology is mainly used for the extraction of bioactive substances and the degradation of biological macromolecules. This review is focused on the mechanism of enzymatic hydrolysis assisted by ultrasonic pretreatment, including the effects of ultrasonic pretreatment on the enzyme structure, substrate structure, enzymatic hydrolysis kinetics, and thermodynamics and the effects of the ultrasonic conditions on the enzymatic hydrolysis results. The development status of ultrasonic devices and the application of ultrasonic-assisted enzymatic hydrolysis in the food industry are briefly described in this study. In the future, more attention should be paid to research on ultrasound-assisted enzymatic hydrolysis devices to promote the expansion of production and improve production efficiency.

Exploring the binding effect and mechanism of glycyrrhizin to ovomucin by combining spectroscopic analysis and molecular docking

Ovomucin (OVM) is an ideal natural macromolecular glycoprotein extracted from eggs with good adhesion. Based on the defect that glycyrrhizin (GL) has good antiviral activity but fast metabolism, this study aimed to explore the binding effect and mechanism of GL to OVM, using multi-spectroscopic techniques, isothermal titration calorimetry (ITC), and molecular docking. The adhesion ability of OVM to the hydrophilic interface and GL was first demonstrated by dual polarization interferometry (DPI) analysis and binding capacity assay, and the OVM-GL complex exhibited a similar affinity for the spike protein of COVID-19. The spectroscopic results show that GL can quench the inherent fluorescence and change the glycosidic bond and secondary structure of OVM. The ITC measurements suggested that the binding was exothermic, the hydrogen bond was the dominant binding force for forming OVM-GL. Finally, molecular docking results indicated that GL has hydrogen bond interaction with several amino acid residues located in α-OVM and β-OVM while embedding into the hydrophobic pocket of OVM via hydrophobic interactions. In conclusion, OVM can adhere to the hydrophilic interface and bind to GL through hydrogen bonding and hydrophobic interactions to form a stable complex, that is expected to be helpful in virus prophylaxis.

Effects of enzyme treatment on the antihypertensive activity and protein structure of black sesame seed (Sesamum indicum L.) after fermentation pretreatment

Effects of enzyme treatment on the hypertensive potential and protein structure of black sesame seed (BSS) were investigated. Compared with BSS, Angiotensin-converting enzyme (ACE) inhibition of fermented black sesame seed (FBSS) has significantly improved after acid protease processing and reached 75.39% at 2 U/g in 3 h. Meanwhile, the zinc chelating ability and antioxidant activity of FBSS hydrolysate as well as surface hydrophobicity, free sulfhydryl content, and peptide content of FBSS protein, were significantly increased. The results illustrated that this strategy promoted the protein unfolding and exposure of hydrophobic residues, thus contributing toward enzymatic hydrolysis. Secondary structure results indicated that the α-helix of FBSS protein and β-sheet of BSS protein decreased after hydrolyzing. The differences in ACE inhibition may also result from the difference in peptide sequence except for peptide content. In conclusion, the combination of fermentation pretreatment and enzyme treatment is an effective method to enhance the antihypertensive potential of BSS.