Identification and evaluation of antioxidant peptides from highland barley distiller's grains protein hydrolysate assisted by molecular docking

Identification, characterization, and molecular docking of immunomodulatory peptides in Astragalus (Astragalus membranaceus (Fisch.)Bge) seed protein hydrolysates

Developing bioactive peptides from natural plant sources into functional foods and immunomodulators is becoming an attractive approach. In this study, the protein hydrolysates (APH) of Astragalus membranaceus (Fisch.)Bge seed was prepared by alkaline protease digestion method, and components with less than 3KDa were obtained by ultrafiltration (UAPH). The peptide sequence of UAPH was identified by UPLC-MS/MS. silico analysis screened 46 peptides with biological activity. Cell experiments and molecular docking results showed that UAPH can regulate the immune activity of RAW264.7 cells by enhancing cell phagocytic activity and ROS generation, upregulating the expression of TNF -α, IL-6, IL-1β, and TLR4. Peptides DWVSLPG, WVSLPGVP, and FTSIVGNVF are expected to contribute to the immune regulatory activity of UAPH. This study first discovered that the hydrolyzed protein of A. membranaceus seed is a source of immunomodulatory agents, revealing the potential of A. membranaceus seed peptides in developing novel and effective immunomodulatory functional foods.

Identification and characterization of novel antioxidant peptides from Yunnan dry-cured beef: A combined in silico and in vitro study

Dry-cured meats are a good natural source of bioactive peptides. However, there is limited information on the composition and antioxidant activity of peptides in Yunnan dry-cured beef (YDB). This study aimed to identify novel antioxidant peptides from YDB using peptidomics, in silico analysis, and in vitro experimental validation while predicting their antioxidant mechanism through molecular docking. A total of 541 peptides were identified in YDB, with the predominant sources being creatine kinase (13.5 %), myosin (10.4 %), and actin (7.4 %). The novel antioxidant peptides VGSYEDPYH (VH9) and FGEAAPYLRK (FK10) demonstrated a high safety profile, with a hemolysis rate of less than 5 %. Notably, VH9 exhibited excellent ABTS radical scavenging activity (IC50 = 19.698 μM), DPPH radical scavenging activity (IC50 = 1500.825 μM), and protection against oxidative stress injury in HepG2 cells. Molecular docking studies revealed that hydrogen bonding and hydrophobic interactions were the primary forces driving the binding of VH9 to the active sites of ABTS, DPPH, Keap1, and myeloperoxidase (MPO). VH9 may protect cells from oxidative damage through radical scavenging, inhibition of reactive oxygen species (ROS) generation, and modulation of the Keap1-Nrf2 antioxidant pathway. Peptides derived from YDB exhibited strong antioxidant activity and showed potential for application as natural antioxidants.

Advances in innovative extraction techniques for polysaccharides, peptides, and polyphenols from distillery by-products: Common extraction techniques, emerging technologies, and AI-driven optimization

Distillery by-products, such as distillers' grains, stillage, and vinasse, are rich in organic compounds and offer immense potential for the recovery of bioactive substances, including polysaccharides, peptides, and polyphenols. The effective utilization of these by-products is critical for achieving long-term sustainability in the distillery sector. This review highlights advancements in extraction techniques, focusing on enzymatic, ultrasound-assisted, and microwave-assisted methods while also exploring emerging approaches such as supercritical fluid extraction, pressurized liquid extraction, pulse electric field, and synthetic biology. These innovative techniques address the limitations of traditional methods by improving extraction yields, reducing processing times, and enhancing sustainability. Additionally, the integration of machine learning and artificial intelligence is discussed as a promising avenue for optimizing extraction parameters and scaling up processes. By evaluating recent achievements and identifying new opportunities, this study aims to promote sustainable practices in the distillery industry, emphasizing economic feasibility, environmental impacts, and resource optimization for value-added product development.

A new technique for antioxidant walnut peptide preparation directly from walnut cake: Enzymatic preparation process optimization coupled with enzyme membrane reactor and kinetic analysis

The lack of scalable production methods limits the commercial production viability of walnut peptides. To overcome this obstacle, enzyme membrane reactors (EMRs) were used to continuously produce bioactive peptides (called CEMR) directly from walnut cake. The optimum operating conditions were pH 10.7, an [E/S] ratio of 11 %, and a temperature of 44 °C, which resulted in a peptide yield of 256.0 ± 4.66 mg/g cake and a protein conversion degree reaching 63.49 ± 0.82 %. Kinetic analysis showed that affinity between alkaline protease and walnut cake can be enhanced by EMR (km decreased, kA increased). The antioxidant results showed that the strongest antioxidant activity was detected in CEMR. The composition of amino acids and molecular weight distribution results showed that the highest content of Glu (20.20 ± 0.48 %), Asp (20.70 ± 0.95 %), and peptides with molecular weight < 1KD (51.92 %) were detected in CEMR. The results of CEMR provide a new option for simplifying the production process of walnut peptide.

Sake lees extract obtained using a novel continuous phase-transition extraction method: evaluation of its bioactive composition, anti-aging efficacy and mechanism

For the high-value utilization of sake lees (SL), it is essential to explore its potential as a resource for anti-aging bioactives. However, the efficient extraction of SL, the compositional benefits provided, and the resulting anti-aging efficacy in vivo remain to be explored. Thus, a novel continuous phase-transition extraction (CPE) method, an amino acid analyzer, LC-MS, and GC-MS, as well as a classic anti-aging model of Caenorhabditis elegans (C. elegans) were adopted. The results showed that compared to ultrasound-assisted extraction, the total amino acid content of SL extract (SLE) obtained using 80% ethanol in CPE increased by 39.64%, with a notable enhancement in the in vitro scavenging ability of free radicals (p < 0.05). In SLE, the hydrophobic, acidic, and basic amino acids with antioxidant activity accounted for 77.11% of total amino acids. New potential anti-aging compounds were identified, including Lys-Gln, Leu-Arg-Lys, and sphinganine. In particular, 4 mg mL-1 SLE not only promoted a 19.32% increase in the lifespan of C. elegans by enhancing oxidative stress and neuroprotective effects but also ameliorated age-related phenotypes like motoricity and age pigment. Further exploration revealed that the efficacy of SLE is mediated by SKN-1/Nrf2 and HSF-1 pathways, which can be confirmed by the upregulation of key genes, such as skn-1 and hsf-1, especially by inducing a 72.73% increase in nuclear transfer of the transcription factor SKN-1/Nrf2. Taken together, SLE obtained by CPE was abundant in bioactives and contains novel components, thus exerting prominent anti-aging effects in vivo. This study provides a new way to obtain anti-aging active substances efficiently, which is beneficial for application in the fields of health foods and cosmetics.

Successive extraction of key protein and polysaccharide from distillers' grains: Optimization, characterization, and economic analysis

Distillers' grains (DGS) are rich in various functional components and have received widespread attention from researchers for their extraction. However, current extraction methods typically isolate only a single component, which leads to low extraction efficiency and high processing costs. This study developed an integrated extraction strategy combining flash extraction with sequential enzymatic hydrolysis to obtain key proteins and polysaccharide components from DGS. Under optimized conditions, the method achieved recoveries of 92.70 %, 78.70 %, and 84.83 % for prolamin, polysaccharide, and gluten, with corresponding purities of 77.53 %, 95.96 %, and 84.81 %. Notably, the flash extraction significantly improved the recovery and purity of prolamin by 57.83 % and 49.54 %, respectively. FTIR spectroscopy comparisons revealed that prolamin exhibited lower solubility (17.19 %) and weaker emulsifying properties (EAI: 43.42 m2/g; ESI: 37.41 min), which were attributed to its high β-sheet content. Conversely, gluten demonstrated higher solubility (52.37 %) and superior emulsifying performance (EAI: 61.23 m2/g; ESI: 47.17 min) due to increased β-turn content. Moreover, the preliminary economic assessment of flash extraction and enzymatic hydrolysis for processing DGS showed a material cost of $952.29 per ton, yielding products with a total market value of $2793.94, indicating a profit margin approximately 2.93 times the material costs, highlighting the potential for industrial-scale implementation in sustainable biorefinery processes. This study successfully achieved the co-extraction of multiple components in DGS and provided a novel approach for the value-added utilization of DGS.

Ultrasound-laccase pre-treatment enhances agarwood essential oil extraction and bioactivity

Agarwood essential oil is prized for its elegant aroma and pharmacological properties; however, the traditional hydrodistillation method suffers from inefficiencies, constraining the industrial potential of agarwood. We proposed an ultrasonic-assisted laccase synergistic pretreatment technique that enhanced extraction throughput by 70.90 % compared to the traditional method by facilitating pore formation in agarwood and expediting the release of essential oil. The essential oil extracted using this method retained a similar aromatic profile to the traditional method but achieved a higher sesquiterpene oxide concentration (95.3 % vs. 89.6 %). Additionally, it exhibited notable improvements in antioxidant activity, acetylcholinesterase inhibition, and α-glucosidase inhibition, attributed to the increased affinity of sesquiterpene oxides for enzymes through hydrogen bonding, covalent interactions, and hydrophobic effects with amino acid residues. This approach not only maximises the efficiency of agarwood essential oil extraction and amplifies its bioactive properties, but also offers a sustainable and eco-friendly alternative, promoting the long-term vitality of the agarwood industry.

Novel anti-oxidative peptides from equine hemoplasma protein hydrolysates: Purification, identification and protective effects on Caco-2 cells

In this study, we purified and identified antioxidant peptides from equine plasma protein hydrolysates and assessed their protective effects against H2O2-induced oxidative stress in Caco-2 cells. Four antioxidant peptides were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in equine plasma protein hydrolysate, namely: GTMVGC (567.69 Da), FGMTST (662.88 Da), VGYHSHF (847.01 Da) and ALSPFFKE (939.18 Da). Among them, ALSPFFKE showed the strongest antidigestive properties after modelled digestion studies. Moreover, ALSPFFKE enhanced intracellular superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities while significantly reducing reactive oxygen species accumulation and malondialdehyde formation in Caco-2 cells. The molecular docking analysis suggested that ALSPFFKE achieves regulation of the Keap1-Nrf2 pathway mainly by forming multiple hydrogen bonds and hydrophobic interactions with key amino acids (Arg380, Ser555, Gln530, Tyr334) in Keap1. These findings suggested that equine plasma peptides hold significant promise for the development of novel, potent, and stable antioxidant functional foods.

Preparation of Acetylcholinesterase Inhibitory Peptides from Yellowfin Tuna Pancreas Using Moderate Ultrasound-Assisted Enzymatic Hydrolysis

Bioactive peptides represent a promising therapeutic approach for Alzheimer's disease (AD) by maintaining cholinergic system homeostasis through the inhibition of acetylcholinesterase (AChE) activity. This study focused on extracting AChE inhibitory peptides from yellowfin tuna pancreas using moderate ultrasound-assisted enzymatic hydrolysis (MUE). Firstly, papain and MUE stood out from five enzymes and four enzymatic hydrolysis methods, respectively, by comparing the degree of hydrolysis and AChE inhibitory activity of different pancreatic protein hydrolysates. Subsequently, the optimal MUE conditions were obtained by single-factor, Plackett-Burman, and response surface methodologies. The pancreatic protein hydrolysate prepared under optimal MUE conditions was then purified by ultrafiltration followed by RP-HPLC, from which a novel AChE inhibitory peptide (LLDF) was identified by LC-MS/MS and virtual screening. LLDF effectively inhibited AChE activity by a competitive inhibition mechanism, with an IC50 of 18.44 ± 0.24 μM. Molecular docking and molecular dynamic simulation revealed that LLDF bound robustly to the active site of AChE via hydrogen bonds. These findings provided a theoretical basis for the valuable use of yellowfin tuna pancreas and introduced a new viewpoint on the potential therapeutic advantages of AChE inhibitory peptides for future AD treatment.

Unraveling novel antioxidant peptides from Asian swamp eel: Identification, in silico selection, and mechanistic insights through quantum chemical calculation and molecular docking

Fifteen novel antioxidant peptides were identified from Asian swamp eel (ASE) hydrolysate through in silico screening, demonstrating ABTS and ORAC activities ranging from 1.17 to 3.28 and 1.94 to 5.67 times higher than Trolox, respectively. Concurrently, four new sequences (AVLW, VWPS, VPWP, and HWDGSLPR) were discovered. The critical role of the hydrogen atom on the tryptophan indole nitrogen in ABTS radical scavenging was elucidated by quantum chemical calculations and subsequent active site methylation experiments, while the significance of hydrogen atoms on both the tryptophan indole nitrogen and tyrosine phenolic hydroxyl groups for ORAC values was emphasized. Moreover, molecular docking analysis demonstrated that ASE antioxidant peptides primarily interacted with myeloperoxidase (MPO) via hydrogen bonds with Arg405, Arg499, Arg590, Gln257, Glu268, His261, and Thr266, and electrostatic interactions with Arg405, Arg590, Glu268, His261, and His502, resulting in a tight binding to MPO.

Exploring novel antioxidant cyclic peptides in corn protein hydrolysate: Preparation, identification and molecular docking analysis

Antioxidant cyclic peptides were successfully identified from a corn protein hydrolysate. Hydrolysate by Alcalase + Flavourzyme showed the highest cyclic peptide purity (48.36 ± 1.81 %) and higher antioxidant activities compared with other hydrolysate. The success of peptide cyclization in hydrolysate was demonstrated by thermogravimetric analysis and thin-layer chromatography (TLC) analysis. Thermogravimetric analysis showed that the thermal stability of hydrolysate after cyclization was significantly increased, which was related to the formation of cyclic peptides. Peptides with molecular weight less than 1000 Da accounted for more than 80 % in hydrolysate after cyclization. After separation using gel silica chromatography and semi-preparative reverse phase high performance liquid chromatography (RP-HPLC), 22 novel antioxidant cyclic peptides were identified by ultra performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF-MS) and orbitrap-tandem mass spectrometry (Orbitrap-MS/MS). Synthetic cyclic peptides with the same sequence were synthesized and characterized for their antioxidant activity. Molecular docking suggested that the free radical molecules could bind with the cyclic backbone and side chain of cyclic peptides through hydrogen bonding, hydrophobic interaction as well as electrostatic interaction. This study has important implications for the high-value utilization of corn protein and new cyclic peptides drugs or functional food development.

Identification of volatile and flavor metabolites in three varieties of broccoli sprouts

Broccoli sprouts are promising functional food sources and their taste and flavor play a pivotal role in the acceptance of consumers. In this study, the flavor profiles of three varieties of broccoli sprouts, namely Bi Lv, You Xiu, and Lv Hua, were comprehensively characterized using HS-SPME-GC/MS analysis. A total of 364 volatile and flavor components across 15 chemical classes were successfully identified. The results revealed a majority of volatile metabolites exhibiting upregulation during the germination process, leading to an enhancement in taste intensity after germination, particularly for umami and sweet tastes, which was associated with an increase in associated amino acids and sugar content. Although the total glucosinolate content in broccoli sprouts has decreased compared to seeds, it remains the primary contributor to the bitterness of broccoli sprouts. The present study elaborated on the flavor contribution of broccoli sprouts, supporting the cultivation and consumption of them as a nutritious food.

Effects of Pretreatment Methods on Gamma-Aminobutyric Acid Enrichment and Quality Improvement in Highland Barley Beverages

Gamma-aminobutyric acid (GABA) is an important neurotransmitter that promotes sleep and reduces anxiety, but its natural synthesis in the body is insufficient, necessitating dietary intake. This study utilized a combination of germination, the addition of active barley powder, and fermentation to enhance GABA content in an enzymatically hydrolyzed highland barley beverage. The samples were divided into five groups: highland barley (HB), germinated highland barley (GB), highland barley supplemented with another high-glutamic-acid decarboxylase-active highland barley powder TB13 (BT), germinated barley supplemented with TB13 (GBT), and germinated barley supplemented with TB13 followed by fermentation (GBTF). The results indicated that all the pretreatments significantly elevated GABA levels, with the GBT sample showing the highest GABA content, which was 2.4 times that of the HB sample. Germination had minimal impact on the taste and aroma of the beverage, while the addition of TB13 active barley powder caused only slight changes to the aroma. The GABA content in the GBTF sample was 2.2 times higher than in the HB sample, and the GBTF sample also exhibited the highest total phenolic content, demonstrating the strongest antioxidant and free-radical scavenging abilities. Furthermore, the GBTF treatment increased acidity, reduced bitterness, and significantly altered the flavor profile of the barley beverage, enhancing its overall quality and consumer appeal as a GABA-rich functional drink.

Molecular investigation of soybean protein for improving the stability of quinoa (Chenopodium quinoa willd.) milk substitute

Soybean could greatly improve stability of quinoa milk substitute. However, the key compound and underlying mechanisms remained unclear. Here we showed that soybean protein was the key component for improving quinoa milk substitute stability but not oil or okara. Supplementary level of soybean protein at 0%, 2%, 4%, and 8% of quinoa (w/w) was optimized. Median level at 4% could effectively enhance physical stability, reduce particle size, narrow down particle size distribution, and decrease apparent viscosity of quinoa milk substitute. Microscopic observation further confirmed that soybean protein could prevent phase separation. Besides, soybean protein showed increased surface hydrophobicity. Molecular docking simulated that soybean protein but not quinoa protein, could provide over 10 anchoring points for the most abundant quinoa vanillic acid, through hydrogen bond and Van-der-Waals. These results contribute to improve stability of quinoa based milk substitute, and provide theoretical basis for the interaction of quinoa phenolics and soybean protein.

Virtual-screening of xanthine oxidase inhibitory peptides: Inhibition mechanisms and prediction of activity using machine-learning

Xanthine oxidase (XO) inhibitory peptides can prevent XO-mediated hyperuricemia. Currently, QSAR about XO inhibitory peptides with different lengths remains to be enriched. Here, XO inhibitory peptides were obtained from porcine visceral proteins through virtual-screening. A prediction model was established by machine-learning. Virtual-screening retained four lengths of peptides, including 3-6. Molecular-docking recognized their binding sites with XO and showed residues W, F, and G were the key amino acids. Datasets of XO inhibitory peptides therewith were established. The optimal model was used to generalize the peptides reported. Results showed that the R2 of the tripeptide, tetrapeptide, pentapeptide and hexapeptide in the generalisation test were R2 = 0.81, R2 = 0.82, R2 = 0.83 and R2 = 0.83, respectively. Overall, this work can serve as a reference for explaining the activity mechanism of XO inhibitory peptides and predicting the activity of XO inhibitory peptides.

Exploration of Bioactive Umami Peptides from Wheat Gluten: Umami Mechanism, Antioxidant Activity, and Potential Disease Target Sites

Umami peptides have the ability to enhance food flavours and have potential health benefits. The objective of this study was to conduct a comprehensive investigation into the umami intensity, taste mechanism, and antioxidant activity of six umami peptides derived from wheat gluten hydrolysates (WGHs) and fermented WGHs. The e-tongue analysis demonstrated that the peptides exhibited a direct proportionality in terms of umami value and concentration, and were capable of enhancing the umami of commercially available condiments. The molecular dynamics simulations demonstrated that the peptides interacted with T1R1/T1R3 receptors via hydrogen bonds, hydrophobic interactions, ionic interactions, and water bridges, thereby producing umami. Furthermore, the DPPH, ABTS, hydroxyl radical-scavenging, and FRAP assays demonstrated that the six peptides exhibited antioxidant activity in vitro. Ultimately, the network pharmacology and molecular docking results indicated that AKT1, JUN, and CASP3 may serve as the core targets for the peptides in the treatment of oxidative diseases. In conclusion, this work offers novel insights into the use of bioactive umami peptides, emphasising their prospective applications in the food and health supplement industries.

Lactobacillus plantarum 69-2 combined with α-lactalbumin hydrolysate alleviates DSS-induced ulcerative colitis through the TLR4/NF-κB inflammatory pathway and the gut microbiota in mice

Ulcerative colitis (UC), an inflammatory bowel disease, seriously affects people's quality of life. Diet-derived active peptides and Lactobacillus plantarum have shown promise for mitigating symptoms of UC. This investigation explored the combined effects of α-lactalbumin (α-LA) hydrolysate, which boasts a high antioxidant capacity, and L. plantarum 69-2 (L69-2) on a colitis mouse model. The results showed that α-LA hydrolysate with a molecular weight <3 kDa obtained with neutral protease had excellent antioxidant activity and potential to enhance probiotic proliferation. Furthermore, the synergistic application of α-LA hydrolysate and L69-2 could alleviate the adverse impact of colon inflammation by reducing oxidative stress and regulating immune disorders. It maintains the intestinal epithelial barrier, thereby reducing immune system over-activation, promoting the colonization of beneficial bacteria, and regulating intestinal immune responses. Simultaneously, it remodels the structure of the disrupted intestinal flora. The increase in the richness and diversity of the flora leads to the production of beneficial metabolites, which in turn inhibits the activation of the TLR4/NF-κB inflammatory pathway. This study provides a novel perspective on milk-derived peptide synergism with probiotics in alleviating UC.

Identification and molecular docking of novel antioxidant peptides from Candida utilis

The current trend is the promotion of antioxidants that are beneficial for both health and the environment. Candida utilis have garnered considerable attention due to their commendable attributes such as non-toxicity and the ability to thrive in waste. Therefore, Candida utilis was used as raw material to isolate and identify new antioxidant peptides by employing methods such as ultrafiltration, DEAE Sepharose Fast Flow, and liquid chromatography-tandem mass spectrometry. The antioxidant mechanism of peptides was investigated by molecular docking. The properties of antioxidant peptides were evaluated using a variety of computational tools. This study resulted in the identification of two novel antioxidant peptides. According to the molecular docking results, the antioxidant mechanism of Candida utilis peptides operates by obstructing the entry to the myeloperoxidase activity cavity. The (-) CDOCKER energy of antioxidant peptides was 6.2 and 6.1 kcal/mol, respectively. Additionally, computer predictions indicated that antioxidant peptides exhibited non-toxicity and poor solubility.

Molecular docking and molecular dynamics simulation of wheat gluten-derived antioxidant peptides acting through the Keap1-Nrf2 pathway

BACKGROUND

In our previous study, we successfully identified five peptides from wheat gluten: Ala-Pro-Ser-Tyr (APSY), Leu-Tyr (LY), Pro-Tyr (PY), Arg-Gly-Gly-Tyr (RGGY) and Tyr-Gln (YQ). Molecular docking and molecular dynamics simulation methods were employed to investigate the interaction between these antioxidant peptides and the Kelch-like ECH-associated protein 1 (Keap1 protein), revealing the molecular mechanism of their non-competitive binding. In addition, the total antioxidant capacity of the five peptides was determined using the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) method.

RESULTS

The affinities of APSY, LY, PY, RGGY and YQ were -8.9, -8.3, -8.5, -9.1 and - 7.9 kcal mol-1, respectively. The five peptides effectively bound to Keap1 protein through hydrogen, π-σ, π-alkyl and alkyl interactions. Significant roles were observed for the P1 pocket residue ARG-415 and the P3 pocket residue ALA-556 in the interactions of the Keap1-peptide complexes. Molecular dynamics simulations further elucidated the dynamic process of peptide binding to the Keap1 protein. All five peptides formed stable complexes with Keap1 protein, with van der Waals forces playing crucial roles in these complex systems, indicative of the peptides' strong binding ability to Keap1 protein. The van der Waals forces were -178.74, -123.11, -134.36, -132.59, and -121.44 kJ mol-1 for the Keap1-APSY, Keap1-LY, Keap1-PY, Keap1-RGGY and Keap1-YQ complexes, respectively. These peptides exhibited excellent antioxidant effects. Among them, the YQ peptide exhibited the highest total antioxidant capacity, with an activity value of 1.18 ± 0.06 mmol Trolox equivalent (TE) L-1 at a concentration of 0.10 mg mL-1. The RGGY, PY, LY and APSY peptides followed in descending order, with activity values of 0.91 ± 0.05, 0.72 ± 0.06, 0.62 ± 0.04 and 0.60 ± 0.05 mmol TE L-1, respectively.

CONCLUSION

These results unveiled the molecular mechanism by which the five antioxidant peptides act on active pockets through the Keap1-Nrf2 signaling pathway, providing a theoretical basis for the development of antioxidants. © 2024 Society of Chemical Industry.

Effect of tremella polysaccharides on the quality of collagen jelly: insight into the improvement of the gel properties and the antioxidant activity of yak skin gelatin

BACKGROUND

The present study aimed to investigate the effects of tremella polysaccharides on the gel properties and antioxidant activity of yak skin gelatin with a view to improving the quality of collagen jellies. The preparation of composite gels were performed by yak skin gelatin (66.7 mg mL-1) and tremella polysaccharides with different concentrations (0, 2, 4, 6, 8 mg mL-1), and finally the collagen jelly was prepared by composite gel (yak skin gelatin: 66.7 mg mL-1; tremella polysaccharides:6 mg mL-1) with the best performance.

RESULTS

Tremella polysaccharides not only improved the hardness, springiness, gel strength, water holding capacity and melting temperature of yak skin gelatin, but also enhanced the composite gel's scavenging activity against ABTS radicals, DPPH radicals, O2 and OH radicals. The filling of tremella polysaccharides into the gelatin network increased the number of crosslinking sites inside the gel, which resulted in the gel network structure becoming dense and orderly. The gel particles became finer and more uniform, and the thermal stability was improved. Furthermore, the sensory score of commercially available gelatin jelly decreased more rapidly during storage compared to the composite gel jelly.

CONCLUSION

The gel properties and antioxidant activity of yak skin gelatin were improved by adding tremella polysaccharides, and then the quality and storage properties of the jelly were improved, which also provided technical reference for the development of functional gel food. © 2024 Society of Chemical Industry.

StackedEnC-AOP: prediction of antioxidant proteins using transform evolutionary and sequential features based multi-scale vector with stacked ensemble learning

BACKGROUND

Antioxidant proteins are involved in several biological processes and can protect DNA and cells from the damage of free radicals. These proteins regulate the body's oxidative stress and perform a significant role in many antioxidant-based drugs. The current invitro-based medications are costly, time-consuming, and unable to efficiently screen and identify the targeted motif of antioxidant proteins.

METHODS

In this model, we proposed an accurate prediction method to discriminate antioxidant proteins namely StackedEnC-AOP. The training sequences are formulation encoded via incorporating a discrete wavelet transform (DWT) into the evolutionary matrix to decompose the PSSM-based images via two levels of DWT to form a Pseudo position-specific scoring matrix (PsePSSM-DWT) based embedded vector. Additionally, the Evolutionary difference formula and composite physiochemical properties methods are also employed to collect the structural and sequential descriptors. Then the combined vector of sequential features, evolutionary descriptors, and physiochemical properties is produced to cover the flaws of individual encoding schemes. To reduce the computational cost of the combined features vector, the optimal features are chosen using Minimum redundancy and maximum relevance (mRMR). The optimal feature vector is trained using a stacking-based ensemble meta-model.

RESULTS

Our developed StackedEnC-AOP method reported a prediction accuracy of 98.40% and an AUC of 0.99 via training sequences. To evaluate model validation, the StackedEnC-AOP training model using an independent set achieved an accuracy of 96.92% and an AUC of 0.98.

CONCLUSION

Our proposed StackedEnC-AOP strategy performed significantly better than current computational models with a ~ 5% and ~ 3% improved accuracy via training and independent sets, respectively. The efficacy and consistency of our proposed StackedEnC-AOP make it a valuable tool for data scientists and can execute a key role in research academia and drug design.

Isolation and Characterization of Antioxidant Peptides from Dairy Cow (Bos taurus) Placenta and Their Antioxidant Activities

Our preliminary study identified dairy cow placenta extract (CPE) as a mixture of peptides with potent antioxidant activity both in vivo and in vitro. However, the specific antioxidant peptides (AOPs) responsible for this activity were not yet identified. In the current study, we employed virtual screening and chromatography techniques to isolate two peptides, ANNGKQWAEVF (CP1) and QPGLPGPAG (CP2), from CPE. These peptides were found to be less stable under extreme conditions such as high temperature, strong acid, strong alkali, and simulated digestive conditions. Nevertheless, under normal physiological conditions, both CP1 and CP2 exhibited significant antioxidant properties, including free-radical scavenging, metal chelating, and the inhibition of lipid peroxidation. They also up-regulated the activities of intracellular antioxidant enzymes in response to hydrogen-peroxide-induced oxidative stress, resulting in reduced MDA levels, a decreased expression of the Keap1 gene and protein, and increased levels of the Nrf2 and HO-1 genes and proteins. Furthermore, CP1 demonstrated superior antioxidant activity compared to CP2. These findings suggest that CP1 and CP2 hold potential for mitigating oxidative stress in vitro and highlight the efficacy of virtual screening as a method for isolating AOPs within CPE.

Structural Characterization and Antioxidant Activity of β-Glucans from Highland Barley Obtained with Ultrasonic-Microwave-Assisted Extraction

In order to efficiently extract β-glucan from highland barley (HBG) and study its structural characterization and antioxidant activity, ultrasonic-microwave-assisted extraction (UME) was optimized by the response surface method (RSM). Under the optimal extraction conditions of 25.05 mL/g liquid-solid ratio, 20 min ultrasonic time, and 480 W microwave intensity, the DPPH radical scavenging activity of HBG reached 25.67%. Two polysaccharide fractions were purified from HBG, namely HBG-1 and HBG-2. Structural characterization indicated that HBG-1 and HBG-2 had similar functional groups, glycosidic linkages, and linear and complex chain conformation. HBG-1 was mainly composed of glucose (98.97%), while HBG-2 primarily consisted of arabinose (38.23%), galactose (22.01%), and xylose (31.60%). The molecular weight of HBG-1 was much smaller than that of HBG-2. Both HBG-1 and HBG-2 exhibited concentration-dependent antioxidant activity, and HBG-1 was more active. This study provided insights into the efficient extraction of HBG and further investigated the structure and antioxidant activities of purified components HBG-1 and HBG-2. Meanwhile, the results of this study imply that HBG has the potential to be an antioxidant in foods and cosmetics.

Ensiled diet improved the growth performance of Tibetan sheep by regulating the rumen microbial community and rumen epithelial morphology

The aim of this study was to investigate the effects of ensiled agricultural byproducts from Qinghai-Tibet plateau on growth performance, rumen microbiota, ruminal epithelium morphology, and nutrient transport-related gene expression in Tibetan sheep. Fourteen male Tibetan sheep were randomly assigned to one of two diets: an untreated diet (without silage inoculum, CON, n = 7) or an ensiled diet (with silage inoculum, ESD, n = 7). The total experimental period lasted for 84 d, including early 14 d as adaption period and remaining 70 d for data collection. The ESD increased average daily gain (P = 0.046), dry matter intake (P < 0.001), ammonia nitrogen (P = 0.045), microbial crude protein (P = 0.034), and total volatile fatty acids concentration (P < 0.001), and decreased ruminal pH value (P = 0.014). The proportion of propionate (P = 0.006) and the copy numbers of bacteria (P = 0.01) and protozoa (P = 0.002) were higher, while the proportion of acetate (P = 0.028) was lower in the sheep fed ESD compared to CON. Pyrosequencing of the 16S ribosomal RNA gene revealed that ESD increased the relative abundance of Firmicutes, Ruminococcus, Lachnospiraceae_AC2044_group, Lachnospiraceae_XPB1014_group, and Christensenellaceae_R-7_group in the rumen (P < 0.05), while decreased the relative abundance of Bacteroidota, Prevotellaceae_UCG-003, and Veillonellaceae_UCG-001 (P < 0.05). Analyses with PICRUSt2 and STAMP indicated that the propionate metabolism pathway was enriched in the sheep fed ESD (P = 0.026). The ESD increased the rumen papillae height (P = 0.012), density (P = 0.036), and surface area (P = 0.001), and improved the thickness of the total epithelia (P = 0.018), stratum corneum (P = 0.040), stratum granulosum (P = 0.042), and stratum spinosum and basale (P = 0.004). The relative mRNA expression of cyclin-dependent Kinase 2, CyclinA2, CyclinD2, zonula occludens-1, Occludin, monocarboxylate transporter isoform 1 (MCT1), MCT4, sodium/potassium pump, and sodium/hydrogen antiporter 3 were higher in the rumen epithelial of sheep fed ESD than CON (P < 0.05). Conversely, the relative mRNA expressions of Caspase 3 and B-cell lymphoma-2 were lower in the sheep fed ESD than CON (P < 0.05). In conclusion, compared with an untreated diet, feeding an ensiled diet altered the rumen microbial community, enhanced nutrient transport through rumen epithelium, and improved the growth performance of Tibetan sheep.