Antioxidant Peptides Research Articles

Antioxidant peptides obtained from abalone muscle hot water extract during in‐vitro simulated digestion and Caco‐2 cell absorption

SummaryAfter abalone muscle hot water extract (AHE) was digested in‐vitro, three components (F1, F2, and F3) were separated using the Sephadex G‐15 column, and the antioxidant activity and absorption across Caco‐2 cells were analysed. The result showed that the half‐maximal inhibitory concentrations of F2 for scavenging hydroxyl and ABTS radicals were 0.763 and 0.028 mg mL−1, respectively, which were lower than those of F1 and F3. Moreover, the Trolox equivalent antioxidant capacity was increased after the F2 was transported through the Caco‐2 cell‐monolayered Transwell chamber. The mass spectrometry analysis revealed that the transported samples contained oligopeptides (Leu‐Tyr, Gly‐Ala‐Ala, and His‐Gly‐Ser‐Ala), and the Leu‐Tyr displayed the highest antioxidant activity and transport rate. Overall, these results suggest that oligopeptides with high antioxidant capacities can be produced from AHE through a combination of in‐vitro digestion and absorption across Caco‐2 cells.

Ultrasound-assisted fermentation for antioxidant peptides preparation from okara: Optimization, stability, and functional analyses

This study investigated the effects of ultrasound-assisted fermentation (UAF) on the preparation of antioxidant peptides (UAFP) from okara and examined their content, chemical structures, and antioxidant activity. After the optimal ultrasonic processing (time, 20 min; frequency, 45 KHz; power, 120 W/L), the peptide content yield reached the maximum of 12.36 ± 0.02 mg/mL, and their DPPH free radical scavenging rate was 65.15 ± 0.32 %. UAF increased the number of globular aggregates with deeper gullies, a looser structure, and higher porosity. The experiments conducted using the oxidative stress injury model of HepG2 cells showed that okara UAFP promoted cell growth and exerted a protective effect. Moreover, ultrasonic treatment remarkably improved the environmental stability (NaCl, glucose, sodium benzoate, temperature, pH, metal ions) and antioxidant activity of UAFP. Concisely, optimal ultrasonic processing can aid the fermentation of agroindustrial by-products to prepare antioxidant peptides, such as natural food antioxidant peptides from soybean waste.

Application of antioxidant peptides derived from goat milk in ginger coffee formulation

Peptides can be obtained from the degradation of goat milk protein by enzymatic hydrolysis method using food-grade papain enzyme. These peptides have antioxidant activity that can be applied to beverage formulations. This study aimed to characterize antioxidative peptides from whey and goat milk and to develop a ginger coffee drink formulation with antioxidant peptides. Protein hydrolysis was performed for 0, 15, and 30 mins and the highest degree of hydrolysis was obtained from protein samples which were hydrolyzed for 15 mins. The whey hydrolysate 15 mins had a protein concentration of 0.54±0.07 mg/mL and one protein band of 17 kDa. Goat milk peptides had a protein concentration of 1.71±0.00 mg/mL and one protein band of 15 kDa. This sample also has the highest antioxidant activity, where Whey peptides had an antioxidant activity of 79.98±0.86% while goat's milk peptides 94.97±0.44%. These two peptides were applied to ginger coffee drink formulation. The formulations with the highest antioxidant activity were ginger coffee with goat milk and whey peptides in a ratio of 4:1 (90.15±1.02%) and ginger coffee with goat milk (85.23±1.15%). Based on results from the organoleptic test, these two formulations were also acceptable to panellists in terms of taste, overall properties, and interest.

Simulated in vitro gastrointestinal digestion of β-lactoglobulin treated by ultrasound: Detection of peptides profile and the antioxidant activity

The influence of ultrasonic pretreatment on the release and antioxidant activity of potential antioxidant peptides after in-vitro simulated gastrointestinal digestion of β-lactoglobulin (BLG) were measured by HPLC-MS/MS, chemical and cellular-based assays. The gastrointestinal digest was fractionated into four fractions by Sephadex G-25 gel filtration column, and fractions showed a considerable ABTS·+ scavenging ability. The fraction with the strongest antioxidant activity was produced by ultrasonicated BLG after gastrointestinal digestion, which relies on ultrasonic-promoted proteolysis to produce many small-molecule antioxidant peptides. The best active fraction has better cellular antioxidant activity and protection of H2O2-induced oxidative HepG2 cell model, which significantly increases the activities of antioxidant enzyme, and is concentration-dependent. HPLC-MS/MS analysis showed that there were more potential antioxidant peptides in the best active fraction. This research will provide a basis for the further application of ultrasonic in dairy products, which can promote the release of more potential antioxidant peptides-derived from gastrointestinal digestion.

Deficiency of connexin43 increases arrhythmias due to increases in Ca2+ and ROS within the mitochondria

Abstract Introduction Connexin43 (Cx43) is a major connexin that forms gap junctions in the hearts and plays important roles in the occurrence of reentrant arrhythmias. Cx43 also exits as hemichannels in the inner mitochondrial membrane (mCx43), but it has not yet been established whether mCx43 are involved in the occurrence of arrhythmias. Purpose To examine what roles mCx43 plays in the occurrence of arrhythmias and whether mitochondrial Ca2+ and ROS are involved in their occurrence. Methods To generate cardiac-specific Cx43-deficient (Cx43-/-) mice, Cx43flox/flox mice were crossed with α-myosin heavy chain cre+/- mice. The resulting offspring, Cx43-/- mice and their littermates (Cx43+/+ mice) were used. Trabeculae were dissected from right ventricles of mouse hearts. Force was measured with a strain gauge, mitochondrial Ca2+ with rhod-2, and mitochondrial ROS with MitoSox Red. The spatial distribution of rhod-2 and MitoSox Red was imaged using confocal microscopy, and it was similar to that of MitoTracker Green within trabeculae, meaning that rhod-2 and MitoSox Red are mainly loaded within the mitochondria. To determine the amount of ROS production, MitoSox Red fluorescence was measured before (Fl) and after the addition of 10 mM H2O2 (FlH2O2), and the ratio of Fl to FlH2O2 was calculated. To estimate arrhythmia susceptibility, the minimal extracellular Ca2+ concentration (Cao), at which arrhythmias were induced by electrical stimulation, was determined (Caomin). Arrhythmias were induced by electrical stimulation with 0.3-s stimulus intervals for 30 s. Results Most of Cx43-/- mice died within 8 weeks (p<0.01). Body and heart weights and tibial length of Cx43-/- mice were similar to those of Cx43+/+ mice. Cx43 was present in the inner mitochondrial membrane in Cx43+/+ mice but not in Cx43-/- mice. Developed force of Cx43-/- mice was similar to that of Cx43+/+ mice at Cao ranging from 0.2 to 6 mM. Rhod-2 fluorescence in Cx43-/- mice was higher than that of Cx43+/+ mice, especially at higher Cao such as 4 and 6 mM (n=7, p<0.01), and the Caomin in Cx43-/- mice was lower than that in Cx43+/+ mice (n=5, p<0.01), suggesting that Cx43-/- mice shows higher arrhythmia susceptibility with higher mitochondrial Ca2+. In Cx43-/- mice, Ru360 (5 μM), a mitochondrial calcium uniporter inhibitor, increased the Caomin, that is, decreased arrhythmia susceptibility with decreases in rhod-2 and MitoSox Red fluorescence (n=6, p<0.05). Additionally, antioxidant peptide SS-31 (50 µM) and N-acetyl-L-cysteine (1 mM) increased the Caomin in Cx43-/- mice (n=5, p<0.05), and the ratio of Fl to FlH2O2 in Cx43-/- mice was larger that that in Cx43+/+ mice, suggesting that an increase in ROS production plays important roles in the occurrence of arrhythmias in Cx43-/- mice. Conclusions Deficiency of Cx43 increases arrhythmia susceptibility with increases in mitochondrial Ca2+ and ROS, providing an attractive therapeutic target for improving arrhythmias in diseased hearts.

Engineering of targeting antioxidant polypeptide nanopolyplexes for the treatment of acute lung injury

The pathogenesis of acute lung injury (ALI) involves various mechanisms, such as oxidative stress, inflammation, and epithelial cell apoptosis. However, current drug therapies face limitations due to issues like systemic distribution, drug degradation in vivo, and hydrophobicity. To address these challenges, we developed a pH-responsive nano-drug delivery system for delivering antioxidant peptides to treat ALI. In this study, we utilized low molecular weight chitosan (LMWC) and hyaluronic acid (HA) as carrier materials. LMWC carries a positive charge, while HA carries a negative charge. By stirring the two together, the electrostatic adsorption between LMWC and HA yielded aggregated drug carriers. To specifically target the antioxidant drug WNWAD to lung lesions and enhance therapeutic outcomes for ALI, we created a targeted drug delivery system known as HA/LMWC@WNWAD (NPs) through a 12-h stirring process. In our research, we characterized the particle size and drug release of NPs. Additionally, we assessed the targeting ability of NPs. Lastly, we evaluated the improvement of lung injury at the cellular and animal levels to investigate the therapeutic mechanism of this drug targeting delivery system.

Abstract 15068: Connexin43 Concerns Arrhythmias Through Changes in Mitochondrial Ca 2+ and ROS

Introduction: Connexin43 (Cx43) is a connexin that forms gap junctions in hearts and exists as hemichannels in the inner mitochondrial membrane (mCx43). It is still unknown whether mCx43 is involved in the occurrence of arrhythmias. Thus, we examined whether deficiency of Cx43 increases arrhythmias and what roles mitochondrial Ca 2+ and ROS play in the occurrence of arrhythmias. Methods: Cardiac-specific Cx43-deficient ( Cx43 -/- ) mice were generated by crossing Cx43 flox/flox mice with α-myosin heavy chain cre +/- mice. The resulting offspring, Cx43 -/- mice and their littermates ( Cx43 +/+ mice), were used. Trabeculae were dissected from mouse hearts. Force was measured with a strain gauge, mitochondrial Ca 2+ with rhod-2, and mitochondrial ROS with MitoSox Red. The spatial distribution of rhod-2 and MitoSox Red imaged with confocal microscopy was similar to that of MitoTracker Green within trabeculae, meaning that rhod-2 and MitoSox Red are loaded within mitochondria. MitoSox Red fluorescence was measured before (Fl) and after the addition of 10 mM H 2 O 2 (FlH 2 O 2 ), and the ratio of Fl to FlH 2 O 2 was calculated. To estimate arrhythmogenesis, the minimal extracellular Ca 2+ concentration (Cao), at which arrhythmias were induced by electrical stimulation (0.3-s stimulus intervals for 30 s), was determined (Cao min ). Results: Cx43 -/- mice died within 8 weeks (p<0.01). Cx43 was present in the inner mitochondrial membrane in Cx43 +/+ mice but not in Cx43 -/- mice. In Cx43 -/- mice, rhod-2 fluorescence was higher than that of Cx43 +/+ mice (n=7, p<0.01), while developed force of Cx43 -/- mice was similar to that of Cx43 +/+ mice. The Cao min in Cx43 -/- mice was lower than that in Cx43 +/+ mice (n=5, p<0.01), suggesting that Cx43 -/- mice shows increased arrhythmogenesis. In Cx43 -/- mice, Ru360 (5 μM), a mitochondrial calcium uniporter inhibitor, increased the Cao min , that is, decreased arrhythmogenesis, with decreases in rhod-2 and MitoSox Red fluorescence (n=6, p<0.05). Antioxidant peptide SS-31 (50 μM) and N-acetyl-L-cysteine (1 mM) increased the Cao min in Cx43 -/- mice (n=5, p<0.05), and the ratio of Fl to FlH 2 O 2 in Cx43 -/- mice was larger than that in Cx43 +/+ mice. Conclusions: Deficiency of Cx43 increases arrhythmogenesis with increases in mitochondrial Ca 2+ and ROS.

Increased Expression Levels of Thermophilic Serine Protease TTHA0724 through Signal Peptide Screening in Bacillus subtilis and Applications of the Enzyme.

The thermostable protease TTHA0724 derived from Thermus thermophilus HB8 is an ideal industrial washing enzyme due to its thermophilic characteristics; although it can be expressed in Escherichia coli via pET-22b, high yields are difficult to achieve, leading to frequent autolysis of the host. This paper details the development of a signal peptide library in the expression system of B. subtilis and the optimization of signal peptides for enhanced extracellular expression of TTHA0724. When B. subtilis was used as the host and the optimized signal peptide was used, the expression level of TTHA0724 was 16.7 times higher compared with E. coli. B. subtilis as an expression host does not change the characteristics of TTHA0724. The potential application fields of TTHA0724 are studied. TTHA0724 can be used as a detergent additive at 60 °C, which can sterilize and eliminate mites while thoroughly cleaning protein stains. Soybean meal enzymatic hydrolysis with TTHA0724 at a high temperature produced a higher content of antioxidant peptides. These results indicate that TTHA0724 has great potential for industrial applications.

Evaluation of the antioxidant activity of Tetraselmis chuii after in vitro gastrointestinal digestion and investigation of its antioxidant peptides

Tetraselmis chuii, belonging to the class Prasinophyceae, are non-toxic microalgae with a fast growth rate and high nutritional value. Currently, the simulated gastrointestinal digestibility of T. chuii and the antioxidant activities of the peptides formed during digestion are unreported. In this study, we aimed to evaluate the antioxidant activity of T. chuii during simulated gastrointestinal digestion using INFOGEST 2.0 method. We also investigated the antioxidant bioactive peptides. In vitro digestion of T. chuii involved treatment with α-amylase, pepsin, and pancreatin during the oral, gastric, and intestinal phases, respectively. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and degree of hydrolysis showed that the proteins of T. chuii were hydrolyzed into small peptides by digestive enzymes. The antioxidant activity of T. chuii increased during digestion, and the intestinal digesta had significantly higher values of 2.2-Diphenyl-1-picrylhydrazyl (DPPH) (increased 2.96-fold and 1.99-fold compared to the oral and gastric digesta, respectively), 2,2′-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) (increased 7.21-fold and 3.38-fold, respectively), ferric reducing antioxidant power (FRAP) (increased to 1.73-fold and 2.17-fold, respectively), and total polyphenol content (TPC) (increased to 4.61-fold and 3.26-fold, respectively). Intestinal digesta were fractionated into <5 kDa (F1), 5–10 (F2), 10–30 (F3), and >30 kDa (F4) fractions by ultrafiltration and evaluated for antioxidant activity. In the fractions, F2 indicated significantly higher antioxidant activity in the DPPH (1.24 ± 0.05 mg trolox equivalent (TE)/g sample) and FRAP (3.66 ± 0.12 mg TE/g sample) assays, while F1 did in the ABTS (47.85 ± 2.54 mg TE/g sample) and TPC (9.85 ± 0.23 mg gallic acid equivalent/g sample) assays. These results suggest that T. chuii and its digestive enzyme products can be successfully used in functional foods as potential antioxidant agents.

Novel antioxidant peptides in fermented pork sausage: Purification, characterization, and cytoprotective functions on Caco-2 cells.

In this study, crude peptides from fermented sausages inoculated with Lactobacillus plantarum CD101 and Staphylococcus simulans NJ201 were initially separated by ultrafiltration and molecular-sieve chromatography. The obtained fractions with high 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and ferric-reducing antioxidant power values (MWCO-1 and fraction A) were used in Caco-2 cells to evaluate their cytoprotective effect on oxidative damage triggered by H2O2. MWCO-1 and A showed slight cytotoxicity. Increased glutathione peroxidase, catalase, and superoxide dismutase activities and decreased malondialdehyde content were observed in the peptide-treated groups. Fraction A was further purified using reversed high-performance liquid chromatography. Eighty potential antioxidant peptides were identified by liquid chromatography with tandem mass spectrometry, and fourteen antioxidant peptides were synthesized. SDEEVEH and FAGDDAPR showed strong DPPH radical scavenging activity, whereas ALELDSNLYR and QEYDESGPSIVHR presented strong ABTS+· scavenging activity. These peptides might have great potential for food and pharmacological applications.

Structure-activity relationship of walnut peptide in gastrointestinal digestion, absorption and antioxidant activity

The structure-activity relationship between digestion of walnut peptide (<3 kDa) and antioxidant activity were explored, and the inhibitory effect of DPP-IV on antioxidant peptide KGHLFPN (Lys-Gly-His-Leu-Phe-Pro-Asn) was selected. After simulated gastrointestinal digestion, the peptides’ antioxidant capacities were enhanced, tertiary structures were weaker, and secondary structures were random coiled. After the digestion, the peptide and C–H phylyl bonds were broken and macromolecular proteins were hydrolyzed. Antioxidant walnut peptide KGHLFPN was a good DPP-IV inhibitor. And 4–8 h may be the optimal time for oral absorption of KGHLFPN in vivo. Therefore, walnut protein hydrolysate (<3 kDa) can be used as an antioxidant precursor, and walnut peptides can be potential food-derived antioxidants.

Antioxidant peptides from alternative sources reduce lipid oxidation in 5% fish oil-in-water emulsions (pH 4) and fish oil-enriched mayonnaise.

Bioinformatics tools were used to predict radical scavenging and metal chelating activities of peptides derived from abundant potato, seaweed, microbial, and spinach proteins. The antioxidant activity was evaluated in 5% oil-in-water emulsions (pH4) and best-performing peptides were tested in mayonnaise and compared with EDTA. Emulsion physical stability was intact. The peptide DDDNLVLPEVYDQD showed the highest protection against oxidation in both emulsions by retarding the formation of oxidation products and depletion of tocopherols during storage, but it was less efficient than EDTA when evaluated in mayonnaise. In low-fat emulsions, formation of hydroperoxides was reduced 4-folds after 5days compared to control. The concentration effect of the peptide was confirmed in mayonnaise at the EDTA equimolar concentration. The second-best performing peptides were NNKWVPCLEFETEHGFVYREHH in emulsion and AGDWLIGDR in mayonnaise. In general, the peptide efficacy was higher in low-fat emulsions. Results demonstrated that peptide negative net charge was important for chelating activity.

Functional modification of thermostable alkaline protease from Bacillus halodurans SE5 for efficient production of antioxidative and ACE-inhibitory peptides from sericin

In this work, the hydrolysis efficiency of recombinant protease_SE5 (r_SE5) on sericin was improved by protein engineering. The S166D variant, obtained from the first round of site-directed mutagenesis, exhibited a 1.4-fold increase in protease activity (602 U/mg) and sericin hydrolysis efficiency (123 μg peptide/mL). Further substitution of Ser166, located on a low-affinity calcium-binding loop, by Glu consequently improved sericin hydrolysis capability. The S166E variant showed remarkable protease activity (671 U/mg) and sericin hydrolysis efficiency (140 μg peptide/mL) with no changes in thermostability compared to r_SE5. Interestingly, the purified S166E efficiently hydrolyzed sericin, with a maximal peptide yield of 540 μg/mL within 60 min. The S166E-derived sericin peptide also exhibited higher ABTS radical scavenging activity (6470 μmol TEAC/L) and angiotensin-I-converting enzyme (ACE) inhibition activity (40%). Additionally, the identification of peptides by LC-MS/MS revealed that two smaller peptides (HHSGVNR and GWWWNSD) with a higher proportion of key amino acid residues were produced by S166E. These peptides were the potential bioactive peptides predicted by the BIOPEP database. Therefore, this study demonstrates the structure–function relevance between the low-affinity calcium-binding loop and hydrolysis of sericin by protease_SE5. S166E is a more powerful protease for producing value-added sericin hydrolysate, which can be used as an active ingredient for food and pharmaceutical applications.

Potential Antioxidant Activity of Novel Antioxidant Peptides from Protein Hydrolysate of Peony Seed Dreg in Chemical and H2O2-Induced RAW264.7 Cells

Peony seed dreg protein (PSDP) was hydrolyzed by proteases secreted by Pseudoalteromonas sp. CSN423. This hydrolysate exhibited excellent antioxidant capability after passing through a 3 kDa ultrafiltration membrane. The antioxidant peptides further purified by size-exclusion chromatography scavenged 2, 2-diphenyl-1-picrylhydrazyl (DPPH∙) (73.0 ± 1.46%) and hydroxyl radicals (∙OH) (81.17 ± 3.69%), protected DNA from oxidative injury, and displayed an oxygen radical absorbance capacity (ORAC) of 4.04 ± 1.11 μmol TE/mg. Furthermore, the antioxidant peptide inhibited apoptosis by inhibiting the production of reactive oxygen species (ROS) and the decrease of mitochondrial membrane potential in H2O2-induced RAW264.7 cells. We identified four major peptides such as YFPF, ECCASLAPL, YVSLK, and YFEM by using mass spectrometry. YFPF showed a potent ∙OH scavenging capability of 75.30 ± 1.08%. ECCASLAPL exhibited higher DPPH∙ scavenging capability (87.20 ± 1.03%) than glutathione (GSH) (49.50 ± 1.50%). Moreover, the peptide YVSLK exhibited the highest ORAC of 2.52 ± 1.20 μmol TE/mg of the identified peptides. This work highlights that the peptides from PSDP might have potential uses in cosmetics, functional foods, and drug development.

Identification of antioxidant peptides targeting Keap1−Nrf2−ARE pathway from in vitro digestion of pork sausage with partial substitution of NaCl by KCl

The Kelch-like ECH-associated protein 1 (Keap1)–nuclear factor erythroid 2–related factor 2 (Nrf2)–antioxidant response elements (ARE) pathway is one of the most important cellular defense mechanisms against oxidative stress. This study focuses on finding antioxidant peptides from in vitro digestion products of pork sausage with partial substitution of NaCl by KCl by virtual screening. Six antioxidant peptides, LIVGFPAYGH, DWWGSTVR, WNSLLIR, IVGFPAYGH, FDNLWDQGL, and LRSPSWDPF, could activate the Keap1–Nrf2–ARE pathway and protect cells from oxidative stress. DWWGSTVR exhibits the most robust activity among them. Further studies indicated that DWWGSTVR could increase the expression of many antioxidant enzymes by enabling the transfer of Nrf2 from the cytoplasm to the nucleus. In summary, these six peptides are proven to be Nrf2 activators and could be used as functional foods to prevent and treat various oxidative stress-induced diseases.

Valorization of sturgeon notochord to obtain antioxidant non-collagenous peptides from the purification process of chondroitin sulfate

Notochord is a cartilage-related by-product of sturgeon processing. To increase the utilization of notochord, we have developed an efficient and eco-friendly extraction process that could recycle non-collagenous peptides during chondroitin sulfate (CS) extraction. Alkaline treatment and ultrafiltration were the two critical steps in the overall extraction process. The results of SDS-PAGE and amino acid composition analysis demonstrated that peptides in low molecular fraction were mainly derived from non-collagenous protein. The non-collagenous peptides exhibited high antioxidant activity. The structural analysis (UV, FTIR, 1H NMR and SAX-HPLC) of CS in high molecular fraction proved high purity CS was obtained using new extraction process. The yield of non-collagenous peptides and CS were 16.8% and 14.5%, respectively. Including undenatured type II collagen, the total utilization rate of notochord was increased to 75.6%. It truly realized the maximum utilization of sturgeon notochord. This extraction process can be used as a reference for other cartilage-related by-products.

Identification of novel antioxidant collagen peptides for preventing and treating H2 O2 -induced oxidative stress in HepG2 cells through in vitro and in silico approaches.

Nowadays, the prevalence of oxidative stress-related chronic diseases is increasing. The identification of novel antioxidant collagen peptides to counteract oxidative stress for individuals' health has gained significant attention. In this study, collagen peptides with antioxidant activities were separated and identified by ion chromatography, reversed-phase high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry. The identified antioxidant collagen peptides were further screened by molecular docking for Keap1-targeted peptide inhibitors and their theoretical interaction mechanisms were investigated. Four novel antioxidant collagen peptides, GPAGPIGPVG, GPAGPpGPIG, ISGPpGPpGPA and IDGRPGPIGPA, with high binding affinity to Keap1 were selected. Molecular docking results demonstrated that the putative antioxidant mechanism of the four antioxidant collagen peptides contributed to their blockage of Keap1-Nrf2 interactions. The results of antioxidant activity of the four antioxidant collagen peptides proved that IDGRPGPIGPA exerted a high scavenging capacity for DPPH and ABTS free radicals, while GPAGPpGPIG improved the resistance of cells to hydrogen peroxide-induced oxidative damage by promoting the activation of intracellular antioxidant enzymes and the production of reduced glutathione in human hepatoma (HepG2) cells. The antioxidant collagen peptides (GPAGPIGPVG, GPAGPpGPIG, ISGPpGPpGPA and IDGRPGPIGPA) will be developed as novel functional food for human health in the near future. © 2023 Society of Chemical Industry.

Effect of Yeast-Derived Peptides on Skeletal Muscle Function and Exercise-Induced Fatigue in C2C12 Myotube Cells and ICR Mice.

In our previous study, the antioxidant peptides (XHY69AP, AP-D, YPLP, and AGPL) were obtained from potential probiotic yeast (Yamadazyma triangularis XHY69), which was selected by our lab from dry-cured ham. This work aimed to explore the effects of yeast-derived peptides on skeletal muscle function and muscle fatigue. Results showed that yeast-derived peptides up-regulated slow-twitch fiber expression and down-regulated fast-twitch fiber expression in C2C12 cells (p < 0.05). The peptides improved mitochondrial membrane potential, adenosine triphosphate generation, and expression of cytochrome-relative genes, thus promoting mitochondrial function. Among these peptides, YPLP up-regulated the relative gene expression of the AMP-activated protein kinase (AMPK) pathway and activated AMPK by phosphorylation. Moreover, YPLP could prolong treadmill time, increase muscle and liver glycogen contents, reduce lactic acid and urea nitrogen contents, and alleviate muscle tissue injury in ICR exercise mice. These results demonstrate that yeast-derived peptides could change the muscle fiber composition, improve muscle function, and relieve muscle fatigue.

Investigative on the molecular mechanism of novel antioxidation peptides by 3D-QSAR, in vitro assay and MD simulations

Three novel antioxidant peptides MHW, YHW and FHW were designed by the analysis of 3D-QSAR. Two accurate CoMFA (Q2 = 0.886 and R2 = 0.988) and CoMSIA (Q2 = 0.737 and R2 = 0.955) models were established. The FTC assay showed that activities of the new peptides on lipid peroxidation is significantly better than that of the template molecule LHW. The results of erythrocyte hemolysis assay demonstrated that MHW, YHW and FHW significantly inhibited AAPH-induced erythrocyte hemolysis by scavenging free radicals at the cellular level. It caused the restoration of intracellular antioxidant enzyme (GSH, CAT and SOD) activities at an acceptable pace and the silencing of intracellular MDA formation. Furthermore, MTT toxicity assay showed that the novel antioxidant peptides had good biocompatibility and no cytotoxicity. Molecular docking and molecular dynamics simulations were used to investigate the molecular mechanism. The results showed that Ser363, Arg380, Asn414 and Arg415 residues played key roles in the antioxidant activity of MHW, YHW and FHW. And they mainly binded to the important residues of Keap1 protein stably by electrostatic force, van der Waals force, H-bonds and hydrophobic interactions, which can better fit the Kelch pocket structural domain of Keap1. Therefore, MHW, YHW and FHW had strong potential to interfere with Keap1-Nrf2 interaction and promoted the enzymatic expression of Nrf2-ARE downstream target pathway.

Inhibitory effects and action mechanism of five antioxidant peptides derived from wheat gluten on cells oxidative stress injury

Our previous study identified five peptides Leu-Tyr (LY), Pro-Tyr (PY), Tyr-Gln (YQ), Ala-Pro-Ser-Tyr (APSY), and Arg-Gly-Gly-Tyr (RGGY) from wheat gluten. However, the mechanism of antioxidant action and structure-function relationship of these five peptides were still unclear. In this study, we found that five peptides induced by AAPH in human embryonic kidney cells (HEK-293) suppressed the intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) production. Moreover, they also upregulated the antioxidant activity-related enzymes (SOD, CAT and GSH-Px) and GSH activities. Additionally, five peptides treatment decreased Keap1 protein level and increased Nrf2 and HO-1proteins levels. It was concluded that five peptides showed promise in activating the Keap1-Nrf2-HO-1 signaling pathway and enhancing the antioxidant defense system. Quantum chemical calculation and molecular docking technologies were used to explore the action mechanism of five wheat peptides. Five antioxidant peptides were able to effectively bind Keap1, and the peptides predominantly formed hydrogen and π bonds during their binding with the active pocket region of Keap1.