Explosion-puffing pretreatment effect on the microstructure of Camellia oleifera Abel. seed and the quality of its oil.

To improve the extraction process and quality of Camellia oleifera Abel. oil (COO). This study examined the influence of explosion-puffing (EP) pretreatment on the physicochemical properties, characteristic compounds and sensory quality of the COO. The results revealed that the seeds after EP pretreatment had cavities surface, which facilitated the extraction of the COO and the dissolution of bioactive compounds. Compared to the untreated group, the oil yield of the 6-7%/20 min was increased from 71.41 to 88.94%, as well as higher levels of squalene, phytosterol, α-tocopherol, and phenolic acids, leading to an increase in the antioxidant abilities. Moreover, the fatty acid composition in the COO was not significantly affected (P > 0.05). W1C, W5S, W3C, W5C, and W1W were the main sensors to distinguish the flavor profile of the COO. In summary, EP pretreatment may be a promising method for enhancing oil yield and quality of the COO.

Interaction between the Neuroprotective and Hyperglycemia Mitigation Effects of Walnut-Derived Peptide LVRL via the Wnt3a/ß-Catenin/GSK-3ß Pathway in a Type 2 Diabetes Mellitus Model.

The term type 3 diabetes mellitus (T3DM) has been considered for Alzheimer's disease (AD) due to the common molecular and cellular characteristics found between type 2 diabetes mellitus (T2DM) and cognitive deficits. However, the specific mechanism of T3DM remains elusive, especially the neuroprotective effects of dietary components in hyperglycemic individuals. In this study, a peptide, Leu-Val-Arg-Leu (LVRL), found in walnuts significantly improved memory decline in streptozotocin (STZ)- and high-fat-diet (HFD)-stimulated T2DM mouse models (p < 0.05). The LVRL peptide also mitigated hyperglycemia, enhanced synaptic plasticity, and ameliorated mitochondrial dysfunction, as demonstrated by Morris water maze tests, immunoblotting, immunofluorescence, immunohistochemistry, transmission electron microscopy, and cellular staining. A Wnt3a inhibitor, DKK1, was subsequently used to verify the possible role of the Wnt3a/ß-Catenin/GSK-3ß pathway in glucose-induced insulin resistance in PC12 cells. In vitro LVRL treatment dramatically modulated the protein expression of p-Tau (Ser404), Synapsin-1, and PSD95, elevated the insulin level, increased glucose consumption, and relieved the mitochondrial membrane potential, and MitoSOX (p < 0.05). These data suggested that peptides like LVRL could modulate the relationship between brain insulin and altered cognition status via the Wnt3a/ß-Catenin/GSK-3ß pathway.

Dual-modified starch micelles as nanocarriers for efficient encapsulation and controlled release of walnut-derived active peptides.

Hydrophilic and hydrophobic modified nanomicelles might be more conducive to passage of the gastrointestinal barrier than walnut peptide (WP). In this study, a novel double modified starch polymer, SB-CST-DCA, was synthesized by grafting sulfabetaine (SB) and deoxycholic acid (DCA) onto corn starch (CST) molecules through etherification and esterification. The modification mechanism was discussed to determine its chemical structure, morphological properties, and thermal stability. Peptide-loaded nanomicelles (SB-CST-DCA-WP) were prepared using WP as the core material. The encapsulation efficiency and peptide loading amount reached 76.90 ± 1.52% and 18.27 ± 0.53%, respectively, with good stability and pH-responsive release behavior observed to effectively control WP release and enhance its antioxidant activity. The composite exhibited safety, non-toxicity, and good blood compatibility at concentrations below 125 µg/mL. Duodenum was identified as the main absorption site with an absorption ratio of 41.16 ± 0.36%.

Walnut-Derived Peptides Ameliorate Scopolamine-Induced Memory Impairments in a Mouse Model via Activation of Peroxisome Proliferator-Activated Receptor γ-Mediated Excitotoxicity.

We investigated the protective effect of walnut peptides and YVPFPLP (YP-7) on scopolamine-induced memory impairment in mice and ß-amyloid (Aß)-induced excitotoxic injury in primary hippocampal neurons, respectively. Additionally, the protective mechanism of YP-7 on neuronal excitotoxicity was explored. Mouse behavioral and hippocampal slice morphology experiments indicate that YP-7 improves the learning and memory abilities of cognitively impaired mice and protects synaptic integrity. Immunofluorescence, western blotting, and electrophysiological experiments on primary hippocampal neurons indicate that YP-7 inhibits neuronal damage caused by excessive excitation of neurons induced by Aß. HT-22 cell treatment with peroxisome proliferator-activated receptor γ (PPARγ) activators and inhibitors showed that YP-7 activates PPARγ expression and maintains normal neuronal function by forming stable complexes with PPARγ to inhibit the extracellular regulated protein kinase pathway. Therefore, YP-7 can ameliorate glutamate-induced excitotoxicity and maintain neuronal signaling. This provides a theoretical basis for active peptides to ameliorate excitotoxicity and the development of functional foods.

Isolation, Virtual Screening, and Evaluation of Hazelnut-Derived Immunoactive Peptides for the Inhibition of SARS-CoV-2 Main Protease.

The aim of this study is to validate the activity of hazelnut (Corylus avellana L.)-derived immunoactive peptides inhibiting the main protease (Mpro) of SARS-CoV-2 and further unveil their interaction mechanism using in vitro assays, molecular dynamics (MD) simulations, and binding free energy calculations. In general, the enzymatic hydrolysis components, especially molecular weight < 3 kDa, possess good immune activity as measured by the proliferation ability of mouse splenic lymphocytes and phagocytic activity of mouse peritoneal macrophages. Over 866 unique peptide sequences were isolated, purified, and then identified by nanohigh-performance liquid chromatography/tandem mass spectrometry (NANO-HPLC-MS/MS) from hazelnut protein hydrolysates, but Trp-Trp-Asn-Leu-Asn (WWNLN) and Trp-Ala-Val-Leu-Lys (WAVLK) in particular are found to increase the cell viability and phagocytic capacity of RAW264.7 macrophages as well as promote the secretion of the cytokines nitric oxide (NO), tumor necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß). Fluorescence resonance energy transfer assay elucidated that WWNLN and WAVLK exhibit excellent inhibitory potency against Mpro, with IC50 values of 6.695 and 16.750 µM, respectively. Classical all-atom MD simulations show that hydrogen bonds play a pivotal role in stabilizing the complex conformation and protein-peptide interaction. Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) calculation indicates that WWNLN has a lower binding free energy with Mpro than WAVLK. Furthermore, adsorption, distribution, metabolism, excretion, and toxicity (ADMET) predictions illustrate favorable drug-likeness and pharmacokinetic properties of WWNLN compared to WAVLK. This study provides a new understanding of the immunomodulatory activity of hazelnut hydrolysates and sheds light on peptide inhibitors targeting Mpro.

A combined in vitro and in silico study of the inhibitory mechanism of angiotensin-converting enzyme with peanut peptides.

Food-derived peptides with low molecular weight, high bioavailability, and good absorptivity have been exploited as angiotensin-converting enzyme (ACE) inhibitors. In the present study, in-vitro inhibition kinetics of peanut peptides, in silico screening, validation of ACE inhibitory activity, molecular dynamics (MD) simulations, and HUVEC cells were performed to systematically identify the inhibitory mechanism of ACE interacting with peanut peptides. The results indicate that FPHPP, FPHY, and FPHFD peptides have good thermal, pH, and digestive stability. MD trajectories elucidate the dynamic correlation between peptides and ACE and verify the specific binding interaction. Noteworthily, FPHPP is the best inhibitor with a strongest binding affinity and significantly increases NO, SOD production, and AT2R expression, and decreases ROS, MDA, ET-1 levels, ACE, and AT1R accumulation in Ang II-injury HUVEC cells.

Effect of bi-enzyme hydrolysis on the properties and composition of hydrolysates of Manchurian walnut dreg protein.

Walnut dreg (WD) active peptides are an important source of dietary antioxidants; however, the products of conventional hydrolysis have limited industrial output owing to poor flavour and low bioactivity. To this end, in this study, we aimed to employ bvLAP, an aminopeptidase previously identified in our research, as well as commercially available Alcalase for bi-enzyme digestion. The flavour, antioxidant activity, and structures of products resulting from various digestion methods were compared. The results showed that the bi-enzyme digestion products had enhanced antioxidant activity, increased ß-sheet content, and reduced bitterness intensity from 9.65 to 6.93. Moreover, bi-enzyme hydrolysates showed a more diverse amino acid composition containing 1640 peptides with distinct sequences. These results demonstrate that bi-enzyme hydrolysis could be a potential process for converting WD into functional food ingredients. Additionally, our results provide new concepts that can be applied in waste processing and high-value utilisation of WD.

Novel strategy to the characterization and enhance the glycemic control properties of walnut-derived peptides via zinc chelation.

This study aimed to utilize zinc coordination to promote the hypoglycemic and antioxidant properties of walnut-derived peptides, such as walnut protein hydrolysate (WPH) and Leu-Pro-Leu-Leu-Arg (LPLLR, LP5), of which LP5 was previously identified from WPH. The optimal conditions for the chelation were a peptide-to-zinc ratio of 6:1, pH of 9, duration of 50 min, and temperature of 50 °C. The WPH-Zn and LP5-Zn complexes increased the α-glucosidase inhibition, α-amylase inhibition, and antioxidant activity more than WPH and LP5 (p < 0.05). In particular, the antioxidant activity of WPH-Zn was superior to LP5-Zn. This is attributable to the WPH containing more aromatic amino acids, carboxylate groups and the imidazole groups, which implies its capacity to potentially coordinate with Zn2+ to form the WPH-Zn complex. Moreover, particle size, zeta potential, and scanning electron microscope indicated that the chelation of Zn2+ by peptides led to intramolecular and intermolecular folding and aggregation.

Mechanism of Intestinal Epithelial Absorption and Electrophysiological Regulation of the Shrimp Peptide QMDDQ.

We investigated the absorption mechanism of the shrimp peptide QMDDQ in small intestines, explored its physiological function in inhibiting neuronal hyperactivity, and verified its entry into the brain in vivo to display functional activity. The everted rat sac model and a Caco-2 paracellular absorption monolayer model were used, indicating that QMDDQ has a good absorption capacity with an apparent permeability coefficient (Papp) > 1 × 10-6 cm/s and the absorption of QMDDQ was concentration-dependent. When the concentration of QMDDQ was 1 mM and the transport time was 180 min, the highest absorption concentration of QMDDQ was 41.17 ± 3.48 µM (P < 0.05). The myosin light-chain kinase (MLCK)-specific inhibitor ML-7 and activator MPA, Western blotting, and immunofluorescence results showed that QMDDQ absorption takes place by mediating the MLCK-p-MLCK-MLC signaling pathway, reversibly opening the zonula occludens-1 (ZO-1), occludin in tight junctions (TJs), upregulating claudin-2 expression, and reaching targets through blood to inhibit neuronal overactivity. Results of fluorescence imaging in vivo verified that QMDDQ could enter the brain 4 h after oral administration. The results provide a theoretical foundation for the mechanism of paracellular absorption of active peptides and a starting point for the development of functional foods for Alzheimer's disease intervention.

Food-Derived Peptides: Beneficial CNS Effects and Cross-BBB Transmission Strategies.

Food-derived peptides, as dietary supplements, have significant effects on promoting brain health and relieving central nervous system (CNS) diseases. However, the blood-brain barrier (BBB) greatly limits their in-brain bioavailability. Thus, overcoming the BBB to target the CNS is a major challenge for bioactive peptides in the prevention and treatment of CNS diseases. This review discusses improvement in the neuroprotective function of food-derived active peptides in CNS diseases, as well as the source of BBB penetrating peptides (BBB-shuttles) and the mechanism of transmembrane transport. Notably, this review also discusses various peptide modification methods to overcome the low permeability and stability of the BBB. Lipification, glycosylation, introduction of disulfide bonds, and cyclization are effective strategies for improving the penetration efficiency of peptides through the BBB. This review provides a new prospective for improving their neuroprotective function and developing treatments to delay or even prevent CNS diseases.

Purification, Identification, Chelation Mechanism, and Calcium Absorption Activity of a Novel Calcium-Binding Peptide from Peanut (Arachis hypogaea) Protein Hydrolysate.

A novel calcium-binding peptide was purified from peanut protein hydrolysate using gel filtration chromatography and identified using HPLC-MS/MS. Its amino acid sequence was determined as Phe-Pro-Pro-Asp-Val-Ala (FPPDVA, named as FA6) with the calcium-binding capacity of 15.67 ± 0.39 mg/g. Then, the calcium chelating characteristics of FPPDVA were investigated using ultraviolet-visible absorption spectroscopy, fluorescence spectroscopy, Fourier transform infrared spectroscopy, particle size, and zeta potential. The results showed that FPPDVA interacted with calcium ions, the chelation of calcium ions induced FPPDVA to fold and form a denser structure, the calcium-binding sites may mainly involve oxygen atoms from the carboxyl residues of Asp and Ala, and Phe possessed contact energy and carbonyl residues of Val. Microstructure analysis showed that FPPDVA-calcium chelate exhibited a regularly ordered and tightly aggregated sheets or block structures. Additionally, FPPDVA-calcium chelate had good gastrointestinal digestive stability and thermal stability. The results of everted rat intestinal sac and Caco-2 cell monolayer experiments showed that FPPDVA-calcium chelate could promote calcium absorption and transport through the Cav1.3 and TRPV6 calcium channels. These data suggest that FPPDVA-calcium chelate possesses the potential to be developed and applied as calcium supplement.

Insights into the Hippocampus Proteomics Reveal Epigenetic Properties of Walnut-Derived Peptides in a Low-Grade Neuroinflammation Model.

Epigenetic mechanisms that dysregulate gene expressions may play a significant role in the development of neurological disorders. However, whether peptides can modulate epigenetic mechanisms remains elusive. This work aimed to investigate the impact of pretreatment with walnut-derived peptides─WHP and YVLLPSPK─on DNA methylation in a low-grade neuroinflammation model. The enriched KEGG pathways included oxidative phosphorylation, riboflavin metabolism, ribosome, and pyrimidine metabolism, which are associated with methylation modification by oral administration of YVLLPSPK in mice with scopolamine-induced cognitive deficits. Furthermore, when THP-1 cells (human acute monocytic leukemia cell line) were exposed to lipopolysaccharide (LPS)-induced inflammation responses, both WHP and YVLLPSPK markedly inhibited the level of Il-6 to 2.05 ± 0.76 and 1.29 ± 0.19 (p < 0.05) and also declined the mRNA expression of Mcp-1 to 1.64 ± 0.02 and 3.29 ± 1.21 (p < 0.01), respectively. Meanwhile, YVLLPSPK decreased the activities of DNA methyltransferases (DNMTs) to 1.03 ± 0.02 and 1.20 ± 0.31 (p < 0.05) based on Dnmt3b and Tet2, respectively. The results indicated that YVLLPSPK modulated DNA methylation in embryonic and neural precursor cells in creating new methylation patterns. Further trials are needed to assess the mechanisms underlying DNA methylation changes through peptides in the pathophysiology of neurological disorders.

Walnut-Derived Peptides Promote Autophagy via the Activation of AMPK/mTOR/ULK1 Pathway to Ameliorate Hyperglycemia in Type 2 Diabetic Mice.

Autophagy flux plays a significant protective role in type 2 diabetes mellitus (T2DM). However, the mechanisms by which autophagy mediates insulin resistance (IR) to ameliorate T2DM remain unclear. This study explored the hypoglycemic effects and mechanisms of walnut-derived peptides (fraction 3-10 kDa and LP5) in streptozotocin and high-fat-diet-induced T2DM mice. Findings revealed that walnut-derived peptides reduced the levels of blood glucose and FINS and ameliorated IR and dyslipidemia. They also increased SOD and GSH-PX activities and inhibited the secretion of TNF-α, IL-6, and IL-1ß. Additionally, they increased the levels of ATP, COX, SDH, and MMP of liver mitochondria. Western blotting indicated that walnut-derived peptides up-regulated LC3-II/LC3-I and Beclin-1 expression, while they down-regulated p62 expression, which may be associated with the activation of the AMPK/mTOR/ULK1 pathway. Finally, the AMPK activator (AICAR) and inhibitor (Compound C) were used to verify that LP5 could activate autophagy through the AMPK/mTOR/ULK1 pathway in IR HepG2 cells.

Athelia rolfsii Exopolysaccharide Protection Against Kidney Injury in Lead-Exposed Mice via Nrf2 Signaling Pathway.

This study aimed to explore protective efficacy of Athelia rolfsii exopolysaccharides (AEPS) to mice kidney against lead-exposed injury with a focus on the role of nuclear factor erythroid-2-related factor 2 (Nrf2) signaling pathway. Lead accumulation in the kidney induces oxidative stress which causes low antioxidant activity, abnormal pathological changes, and apoptosis. Here, the changes in lead levels in the kidney and whole blood proved that AEPS inhibited lead accumulation. It might be related to AEPS enhancing glutathione (GSH) levels and glutathione-s-transferase (GST) activities, as well as the protein abundances of multidrug resistance-associated protein 1 (MRP1) and multidrug resistance-associated protein 2 (MRP2). Moreover, AEPS increased antioxidant activity by upregulating superoxide dismutase (SOD), catalase (CAT) activities, downregulating malondialdehyde (MDA) levels. It also restored kidney function by decreasing blood urea nitrogen (BUN) and creatinine (CRE) levels in the serum. Histopathologic analysis showed that AEPS alleviated the kidney injury induced by lead, too. AEPS also showed anti-apoptosis effect by downregulating caspase-3 and bax expression and upregulating bcl-2 expression. Importantly, AEPS activated Nrf2 signaling pathway by promoting nuclear translocation of Nrf2. However, all-trans-retinoic acid (ATRA), an Nrf2 inhibitor, reversed the effects on AEPS to activation of Nrf2, enhancement of antioxidant, alleviation of kidney injury, restoration of kidney function, prevention of apoptotic, and facilitation of lead exclusion. In brief, AEPS showed kidney protective effect and facilitated lead-expulsion in an Nrf2-dependent manner.

Improving ACE inhibitory activity of hazelnut peptide modified by plastein: Physicochemical properties and action mechanism.

The plastein reaction can increase the activity of angiotensin-converting enzyme (ACE) inhibitory peptides, but the underlying mechanism is unknown. Hence, hazelnut protein hydrolysate and hazelnut peptide YLVR were used as substrate to explore the effect of plastein on physicochemical properties and the mechanism of structural change. The increase in turbidity and particle size and the decrease in free amino groups indicated that the reaction occurred via condensation. The modified products of YLVR were identified by NANO-HPLC-MS/MS, indicating that the N-terminal homologous amino acid aggregates in the plastein. Novel ACE inhibitory peptide YYLVR, YLLVR, and YYLLVR were synthesized and their inhibition rates were 66.35, 72.61, and 89.10 %, respectively, which were higher than that of YLVR (52.58 %). MD simulation showed that YYLLVR exhibited the lowest binding energies of -35.98 ± 2.30 kcal/mol to ACE. Taken together, plastein reaction is a promising strategy for inducing structural modifications to improve the activity of peptide.

Polysaccharides-based delivery system for efficient encapsulation and controlled release of food-derived active peptides.

A polysaccharides-based delivery system was designed to encapsulate and control the release of peanut peptide (PP). The PP-loaded polyelectrolyte complex (TMC-PP-SA) was fabricated based on the electrostatic self-assembly between n-trimethy chitosan (TMC) and sodium alginate (SA). The complex exhibited uniform spherical morphology, satisfactory stability and high encapsulation efficiency. In vitro release behavior indicated that TMC-PP-SA polyelectrolyte complex could inhibit the release of PP at simulated gastric medium and enhance the release of PP at simulated intestinal medium. Moreover, the antioxidant activity of PP after encapsulation was significantly improved compared with that of directly digested PP. Ex vivo intestinal permeation study confirmed that about 41.76 ± 1.43% PP in TMC-PP-SA could be absorbed in the intestinal. The cytotoxicity measurement indicated that the fabricated TMC-PP-SA polyelectrolyte complex was biocompatible and nontoxic. Therefore, these results indicated that the polysaccharides-based delivery system had great potential in protecting active peptides from degradation and facilitating their absorption.

Insights into the hippocampus proteome and phosphorylation modification alterations in C57BL/6 revealed the memory improvement mechanisms of a walnut-derived peptide.

This work aimed to explore the underlying mechanisms of memory improvement effects of a walnut derived peptide WNP-10. The morris water maze test, combined with ultrastructural observation, hematoxylin and eosin and Nissl staining showed that WNP-10 significantly improved the learning and memory capability of the scopolamine-injured mice. The four-dimensional label-free quantification proteomics analysis identified 88 differentially expressed proteins in the WNP-10-treated group compared with scopolamine-induced impairment group. Pathway enrichment analysis and western blotting demonstrated that the WNP-10 can regulate the phosphatidylinositol-3-phosphate 5-kinase, cathepsin L, N-acetylgalactosamine 6-sulfate sulfatase and AP-3 complex subunit mu-1 expression to affect inositol phosphate metabolism, thereby maintaining lysosome homeostasis in scopolamine-injured mice. Notably, the results of phosphoproteomics demonstrated that WNP-10 administration resulted in the increased phosphorylation of phosphatidylinositol-3-phosphate 5-kinase. These findings provide novel insights into the underlying mechanism of memory improvement of walnut peptides.

Walnut-Derived Peptide Enhances Mitophagy via JNK-Mediated PINK1 Activation to Reduce Oxidative Stress in HT-22 Cells.

Mitophagy has a neuroprotective effect on reactive oxygen species (ROS)-induced neurodegenerative diseases. The walnut-derived polypeptide (TW-7) has antioxidant activity and protects nerves by promoting autophagy. However, its action mechanism against oxidative stress through mitophagy remains obscure. Therefore, we aimed to assess the effects of TW-7 on HT-22 cells under oxidative stress. Mitochondrial ultrastructure and cristae number were observed by transmission electron microscopy. The results showed that TW-7 (100 µM) restored the fluorescence intensity of the mitochondrial membrane potential to 0.99 ± 0.04 (P < 0.05), decreased H2O2-induced opening of mitochondrial permeability transition pores, and inhibited mitochondrial bioenergetic deficits. Moreover, it significantly increased activities of antioxidant enzymes to 186.88 ± 5.40 U/mgprot, 40.08 ± 0.87 mU/mgprot, and 23.57 ± 0.77 U/mgprot (P < 0.05), based on superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) assay results, respectively. Consistently, it decreased cellular and mitochondrial ROS levels by 51.71 ± 0.81 and 49.75 ± 0.69% (P < 0.05). TW-7 also downregulated C-Jun N-terminal kinase (JNK) phosphorylation and activated PTEN-induced putative kinase 1 (PINK1)-mediated mitophagy in H2O2-induced HT-22 cells treated with JNK activator (anisomycin) and inhibitor (SP600125). Furthermore, TW-7 inhibited the mitochondrial apoptosis pathway by downregulation of the cytoplasmic cytochrome C, caspase-9, and cleaved-caspase-3 expression. Additionally, BDNF and SNAP-25 levels significantly increased to protect the synaptic function. Collectively, TW-7 improved oxidative stress-mediated nerve cell injury via JNK-regulated PINK1-mediated mitophagy.

Walnut peptide WEKPPVSH in alleviating oxidative stress and inflammation in lipopolysaccharide-activated BV-2 microglia via the Nrf2/HO-1 and NF-κB/p38 MAPK pathways.

The peptide WEKPPVSH from walnut protein hydrolyzate was used to evaluate the antioxidant and anti-inflammatory protective effect on lipopolysaccharide (LPS)-activated BV-2 microglia and its possible mechanism. The results indicated that WEKPPVSH significantly decreased nitric oxide (NO) and reactive oxygen species (ROS) generation in a dose-dependent manner, and significantly up-regulated superoxide dismutase and catalase activities (P < 0.01). Results of enzyme-linked immunosorbent assay (ELISA) showed that WEKPPVSH significantly mitigated the secretion of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) (P < 0.01). Immunofluorescence analysis exhibited that WEKPPVSH down-regulated p65 translocation to the cell nucleus. Western blotting showed that WEKPPVSH up-regulated the expression of nuclear factor erythroid 2-related factor (Nrf2) and heme oxygenase-1 (HO-1), and down-regulated the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), p-IκB/IκB, p-p65/p65 and p-p38/p38. In summary, WEKPPVSH might protect against oxidative stress and inflammation in LPS-stimulated BV-2 microglia by enhancing the Nrf2/HO-1 signaling pathway and blocking the nuclear factor-κB/p38 mitogen - activated protein kinase (NF-κB/p38 MAPK) signaling pathway. The results provided an experimental basis for the research and development of walnut peptide products.

Pine nut antioxidant peptides ameliorate the memory impairment in a scopolamine-induced mouse model via SIRT3-induced synaptic plasticity.

This study aimed to investigate the effects of a pine nut albumin hydrolysate (fraction <3 kDa) and of its short peptide derivative, Trp-Tyr-Pro-Gly-Lys (WYPGK), on synaptic plasticity and memory function in scopolamine-induced memory-impaired mice, as well as the potential underlying mechanism in PC12 cells. In the scopolamine-induced mouse model, the results revealed that the fraction <3 kDa and WYPGK enhanced synaptic plasticity and improved learning and memory function. H&E and Nissl staining analysis showed that the damage in hippocampal neurons was decreased. Golgi staining and transmission electron microscopy further revealed that the enhanced synaptic plasticity was associated with increased dendritic spine abundance and synaptic density. In an H2O2-induced PC12 cell model, treatment with mitochondrial sirtuin 3 (SIRT3) inhibitor and inducer molecules confirmed that the <3 kDa fraction and WYPGK activated SIRT3, leading to the decrease in Ace-SOD2 acetylation and increasing the expression of SYP, SYN-1, SNAP25, and PSD95, thus enhancing synaptic plasticity. The <3 kDa fraction and WYPGK also activated the ERK/CREB pathway and upregulated the expression of brain-derived neurotrophic factor. Our results show that fraction <3 kDa and WYPGK improve learning and memory ability through SIRT3-induced synaptic plasticity in vitro and in vivo.