Isolation, Identification, and Immunomodulatory Mechanism of Peptides from Lepidium meyenii (Maca) Protein Hydrolysate

Immunomodulatory peptides from sturgeon cartilage: Isolation, identification, molecular docking and effects on RAW264.7 cells

Sturgeons (Acipenseridae), ancient fish known for their caviar, produce underutilized by-products like protein-rich cartilage, which is a source of high-quality bioactive peptides. This study investigates immunomodulatory peptides from sturgeon cartilage hydrolysates mechanisms. The study found that sturgeon cartilage hydrolysate F2-7 and its key peptides(DHVPLPLP and HVPLPLP)significantly promoted RAW267.4 cell proliferation, NO release, and phagocytosis (P < 0.001).Additionally, western blotting confirmed that F2-7 enhances immune response by increasing the expression of P-IKKα/β, IΚΚ, p65, and P-p65 proteins in the NF-κB signalling pathway (P < 0.01). Molecular docking further demonstrated that DHVPLPLP and HVPLPLP bind to NF-κB pathway proteins via hydrogen bonding, with low estimated binding energies (-2.75 and -1.64; -6.04 and -4.75 kcal/mol), thus establishing their role as key immune peptides in F2-7. Therefore, DHVPLPLP and HVPLPLP have the potential to be developed as dietary supplements for immune enhancement. Their ability to enhance immune function provides a theoretical basis for novel immune supplements.

Maca (Lepidium meyenii Walp.) inhibits HIV-1 infection through the activity of thiadiazole alkaloids in viral integration

ETHNOPHARMACOLOGY RELEVANCE

Lepidium meyenii Walp. (maca) has been traditionally used for centuries in the Central Andes region both as food and as medicine. In the last decades, its fertility enhancer properties have gained importance, with the majority of the scientific literature related to this topic. However, other traditional uses are less known as metabolic or infectious diseases.

AIM OF THE STUDY

The main purpose of this study is to investigate the anti-infectious activity of L. meyenii, specifically in HIV-1 infection. There are previous reports of the transcriptional related activity of L. meyenii extracts in human T lymphocytes via transcription factors as NF-κB. Since T lymphocytes are the main target of HIV-1 infection and NF-κB is strongly involved in HIV-1 transcription, L. meyenii could display antiviral activity.

MATERIAL AND METHODS

Chromatography and spectroscopy techniques were used to isolate and identify the compounds in the active extracts. An antiviral assay system based on recombinant viruses was used to evaluate the anti-HIV activity. Cell toxicity was tested for all the extracts and compounds. Viral entry was studied using VSV-HIV chimera viruses and reverse transcription and viral integration were studied by qPCR of viral DNA in infected cells. Finally, viral transcription was studied in primary lymphocytes transfected with HIV-1 or NF-κB luciferase reporter plasmids.

RESULTS

n-Hexane extracts of purple maca displayed anti-HIV activity in an in vitro assay. A bioassay-guided fractionation led to the identification of three thiadiazole alkaloids with antiviral activity. All the compounds were able to inhibit HIV infection of MT-2 cell lines and primary lymphocytes (PBMCs) with IC50 values in the low micromolar range. The mechanism of action differs between the three compounds: one of them showed activity on viral entry, and all the three compounds inhibited viral integration at low concentrations. Remarkably, none of the compounds inhibited reverse transcription or viral transcription.

CONCLUSIONS

n-Hexane extracts of the purple ecotype of L. meyenii inhibit HIV-1 infection in vitro and three active thiadiazole alkaloids were isolated acting mainly on viral integration and viral entry.

Extraction, purification, and mechanism of immunomodulatory peptides obtained from silkworm pupa protein hydrolysate

Silkworm pupa, a by-product of silk reeling, is rich in protein; however, it has traditionally been used as animal feed. This study isolated and purified peptides from the enzymatic hydrolysates of silkworm pupa protein, thus effectively enhancing its utilization. The immune activity of these peptides was evaluated in macrophages, and 609 peptides were identified using LC-MS/MS. These active peptides were screened based on their toxicity, allergenic, and biological activity, and their interactions with TLR2 and TLR4/MD-2 were predicted via molecular docking. Results indicated that APFAPAPL, YLPPFNSF, and FIPNEAFAGRPF could strongly bind to TLR2 and TLR4/MD-2 through hydrogen bonding and hydrophobic interactions. These peptides were synthesized using solid-phase synthesis, and their immune activity was verified by proliferation, NO, ROS and TNF-α secretion assays. All three peptides promoted the proliferation, phagocytosis, and secretion of ROS and TNF-α by macrophages. Western blot analysis showed that the peptides activated RAW 264.7 cells via the NF-κB and MAPK signaling pathways, mediated by TLR2 and TLR4/MD-2 receptors. Therefore, this study provides a new understanding of the immunomodulatory activity of silkworm pupa proteins, implying their potential use as functional food ingredients.

Immunomodulatory activity and molecular mechanisms of action of peptides derived from casein hydrolysate by alcalase and flavourzyme based on virtual screening

This study aimed to screen novel immunomodulatory peptides from casein hydrolysates (CH) using alcalase and flavorzyme by virtual screening, and their molecular mechanism were further studied. Based on the primary structural characteristics of immunomodulatory peptides, along with their hydrophobicity and isoelectric point, 3 novel immunomodulatory peptides (ALPMHIR, AMKPWIQPK, NPWDQVKR) were quickly found using virtual screening. These peptides exhibited strong interactions with TLR2/TLR4 through hydrogen bonding and hydrophobic interactions. Molecular docking verified that the key binding sites, such as Ile733, Ala732, and Phe774 in TLR2/TLR4 contributed to docking. Interestingly, the peptide AMKPWIQPK exhibited the strongest immunomodulatory activity and anti-inflammatory activity as 2-way immunomodulatory peptides. Based on Western blot analysis and validation using specific inhibitors against MAPK/NF-κB signaling pathways, the results demonstrated that AMKPWIQPK could recognize the TLR2 and TLR4 receptor of the macrophages to upregulate the p-IκBα, p-p38, and p-p65, and further activated the MAPKs/NF-κB signaling pathways to enhance the immunomodulatory activity. These results confirmed that screening and optimizing immunomodulatory peptides by virtual screening and molecular docking were a novel and rapidly feasible method. The peptide AMKPWIQPK was expected to be used as natural-derived immunomodulatory active ingredients in nutritional health care and functional foods.

Novel casein-derived immunomodulatory peptide PFPEVFG: Activity assessment, molecular docking, activity site, and mechanism of action

Presently, there is a gap in the knowledge of the structure-activity relationship of immunomodulatory peptides. In this study, PFPEVFG was selected as a peptide with immunomodulatory activity from casein hydrolysate by virtual screening, and its immunomodulatory activity was verified by the phagocytosis, proliferation, and expression of cytokines (IL-6, IL-1β, TNF-α) and chemokines (CXCL1, CXCL2) in RAW 264.7 macrophages. Next, molecular docking and double-stranded small interfering RNA mutually verified that the immunomodulatory activity of PFPEVFG was mediated by TLR2 and TLR4. Furthermore, the highest occupied molecular orbital (HOMO) analysis showed that the C19=O20 site with a HOMO contribution of 32.22988% was its active site, and the phenylalanine, where the C19=O20 site was located, was its active amino acid. Finally, the combination of pathway inhibitors and western blot revealed that PFPEVFG activated macrophages through the nuclear factor-κB signaling pathway. In summary, this study provided a new perspective on deeply understanding the structure-activity relationship of casein-derived immunomodulatory peptides, as well as a further theoretical and technological basis for the application of immunomodulatory peptides.

New Insights into the Structure-Activity Relationship of a Novel Immunomodulatory Peptide (HPHPHLSF) from Casein Hydrolyzed by Kluyveromyces marxianus JY-1: Molecular Docking, Interaction Evaluation, and HOMO Analysis

Casein is rich in immunomodulatory peptides. In this study, the release of casein-derived immunomodulatory peptides by Kluyveromyces marxianus JY-1 was investigated for the first time, and an immunosuppressive mouse model was used to evaluate the immunomodulatory activity in the casein hydrolysate. The results showed that the cellular and humoral immunity of immunosuppressed mice could be significantly enhanced by casein hydrolysate. Peptide HPHPHLSF with high immunomodulatory activity from casein hydrolysate was screened using the virtual screening technique. HPHPHLSF possessed strong immunomodulatory activity and significantly upregulated the expression of IL-6, IL-1β, and TNF-α. Next, the interaction of HPHPHLSF with TLR2/4 on the cell surface of RAW264.7 cells was further elucidated by molecular docking and combined analysis of double-stranded small interfering RNA and receptor inhibitors. Further, the results of the highest occupied molecular orbital energy distribution elucidated that the histidine active site C48═O49 played an important role in the immunomodulatory activity of HPHPHLSF. This study confirmed that casein hydrolyzed by K. marxianus JY-1 was a natural immunomodulator, while the structure-activity relationship analysis provided new theoretical and technical support for the targeted preparation and screening of casein-derived immunomodulatory peptides.

Plant-Derived as Alternatives to Animal-Derived Bioactive Peptides: A Review of the Preparation, Bioactivities, Structure-Activity Relationships, and Applications in Chronic Diseases

Background/Objectives: At present, a large number of bioactive peptides have been found from plant sources with potential applications for the prevention of chronic diseases. By promoting plant-derived bioactive peptides (PDBPs), we can reduce dependence on animals, reduce greenhouse gas emissions, and protect the ecological environment. Methods: In this review, we summarize recent advances in sustainably sourced PDBPs in terms of preparation methods, biological activity, structure-activity relationships, and their use in chronic diseases. Results: Firstly, the current preparation methods of PDBPs were summarized, and the advantages and disadvantages of enzymatic method and microbial fermentation method were introduced. Secondly, the biological activities of PDBPs that have been explored are summarized, including antioxidant, antibacterial, anticancer and antihypertensive activities. Finally, based on the biological activity, the structure-activity relationship of PDBPs and its application in chronic diseases were discussed. All these provide the foundation for the development of PDBPs. However, the study of PDBPs still has some limitations. Conclusions: Overall, PDBPs is a good candidate for the prevention and treatment of chronic diseases in humans. This work provides important information for exploring the source of PDBPs, optimizing its biological activity, and accurately designing functional foods or drugs.

Emerging production techniques and potential health promoting properties of plant and animal protein-derived bioactive peptides

Bioactive peptides (BPs) are short amino acid sequences that that are known to exhibit physiological characteristics such as antioxidant, antimicrobial, antihypertensive and antidiabetic properties, suggesting that they could be exploited as functional foods in the nutraceutical industry. These BPs can be derived from a variety of food sources, including milk, meat, marine, and plant proteins. In the past decade, various methods including in silico, in vitro, and in vivo techniques have been explored to unravel underlying mechanisms of BPs. To forecast interactions between peptides and their targets, in silico methods such as BIOPEP, molecular docking and Quantitative Structure-Activity Relationship modeling have been employed. Additionally, in vitro research has examined how BPs affect enzyme activities, protein expressions, and cell cultures. In vivo studies on the contrary have appraised the impact of BPs on animal models and human subjects. Hence, in the light of recent literature, this review examines the multifaceted aspects of BPs production from milk, meat, marine, and plant proteins and their potential bioactivities. We envisage that the various concepts discussed will contribute to a better understanding of the food derived BP production, which could pave a way for their potential applications in the nutraceutical industry.

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-1β (IL-1β). 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.

Isolation, identification of antioxidant peptides from earthworm proteins and analysis of the structure-activity relationship of the peptides based on quantum chemical calculations

Earthworms are emerging sources of edible animal proteins. Earthworm extracts exhibit good in vivo antioxidant activity after oral administration. To better understand the antioxidant activity of earthworms, antioxidant peptides derived from earthworm proteins after gastrointestinal digestion were isolated and identified, and their structure-activity relationships were analysed in this research. Results showed that earthworm protein gastrointestinal digestion products exhibited good antioxidant activity, and 6030 peptide sequences were identified after separation using ion-exchange and gel-chromatography columns. Eleven peptides were screened using computer simulation activity scores, among which AFWYGLPCKL, WPWQMSLY, and GCFRYACGAFY showed the best antioxidant activities. Highest Occupied Molecular Orbital (HOMO) analysis indicated that N29-H10, O122-H38, and the peptide bond binding sites of serine and leucine were active sites of peptides AFWYGLPCKL, GCFRYACGAFY, and WPWQMSLY, respectively. This study provides a new understanding of substance basis of antioxidant activity in earthworms and contributes to application of earthworm proteins as antioxidants in health-foods.

Effects of Black Maca supplement on isokinetics muscular performance of elite women's handball players: placebo-controlled, crossover study

Background

The aim of this study was to investigate the changes in isokinetic muscular performance among female adolescent elite handball athletes with the supplementation of Black Maca (BM).

Methods

Eight elite handball athletes were recruited for the present study. The intake capsules contained 2,500 mg of 100% concentrated BM extract and a placebo each, for 4 weeks. Isokinetic muscular performance and physical fitness were measured three times at 4-week intervals after the intake of BM and placebo, including baseline.

Results

The one-way Analysis of Variance (ANOVA) analysis showed a significant improvement in 20 m-shuttle run (P < 0.001), 30°/s flexor (P < 0.01), and 120°/s flexor (P < 0.01) in isokinetic muscle function of the trunk, and 180°/s right extensor (P < 0.05), 180°/s left extensor (P < 0.05), and 180°/s left flexor (P < 0.01) in isokinetic muscle function of the knee, after BM supplementation. Post-hoc analysis indicated that the BM group had significantly higher results compared to the baseline and placebo groups in terms of 20 m-shuttle run, 30°/s flexor and 120°/s flexor of the trunk, 180°/s right extensor, 180°/s left extensor, and 180°/s left flexor of the knee.

Conclusion

BM supplementation can have a positive effect on improving the performance of elite handball players who engage in high-intensity movements by enhancing their isokinetic muscle function and endurance.

The maca protein ameliorates DSS-induced colitis in mice by modulating the gut microbiota and production of SCFAs

Maca is a functional food with anti-inflammatory activity, and it is rich in protein. Currently, inflammatory bowel disease (IBD) is a common gastrointestinal disease. However, there is little research focusing on the effect of maca protein (MCP) on IBD. In this study, we extracted MCP from maca root and explored its effect and mechanism on improving dextran sodium sulfate (DSS)-induced IBD in mice. The results indicated that MCP intervention alleviated the clinical symptoms and colon tissue damage of mice with DSS-induced colitis and inhibited the expression of inflammatory factors. Moreover, it can modulate the gut microbiota composition in mice with DSS-induced colitis. The regulation is achieved by reducing the relative abundance of the IBD-exacerbating key bacterial genera: Lachnospiraceae_NK4A136_group, Bacteroides, Desulfovibrio, Prevotella, Helicobacter and Sutterella, while increasing the relative abundance of the IBD-alleviating key bacterial genera: norank_f_Muribaculaceae, Lactobacillus, Oscillospira, Akkermansia and Bifidobacterium. MCP can also promote the production of short-chain fatty acids (SCFAs). The further western blotting results indicated that MCP can regulate the Treg/Th17 immune balance in mice with colitis via the SCFAs-GPR41/43/HDAC1 signaling pathway. Overall, MCP can alleviate colitis by comprehensively regulating the gut microbiota and inflammatory response. It may be a promising functional component that reduces the risk of colitis by maintaining intestinal health.

Structure Characterization and Immunomodulatory Activity of Misgurnus anguillicaudatus Carbohydrates

Misgurnus anguillicaudatus, also known as oriental weather loach, is widely consumed and favored in East Asia due to its superior nutritional values and excellent flavor. In this study, a crude Misgurnus anguillicaudatus carbohydrates (MAC) was isolated from Misgurnus anguillicaudatus. Subsequently, two parts, which were named MAO and MAP, respectively, were separated from MAC, and their primary structures and immunomodulatory activity were investigated. The results showed that MAO had a molecular weight of 2854 Da, and principally consisted of arabinose (77.11%) and rhamnose (21.97%), together with minor levels of fucose (0.92%); MAP, with a molecular weight of 3873 Da, was mainly composed of fucose (87.55%) and a small amount of rhamnose (8.86%) and galactose (3.59%). The in vitro assay showed that MAC could significantly enhance the proliferation of macrophages without cytotoxicity and increase the production of immune substances (TNF-α, IL-6). Together with Western blot results, we speculated that MAC could stimulate RAW264.7 murine macrophage cells to secrete TNF-α and IL-6 through up-regulating TLR4-MAPK-p38 signaling pathways. The results indicated that MAC could be a potential immune agent and might provide meaningful information for further chain conformation and immune mechanism research.

Immune Enhancement of Clam Peptides on Immunosuppressed Mice Induced by Hydrocortisone

Clam peptides, marine-derived biological peptides, have been broadly investigated and applied as health foods, among which immunomodulation is one of their biological activities that cannot be ignored in vivo. In this study, we concentrated on exploring the effects of Ruditapes philippinarum peptides (RPPs) on immunomodulation and the balance of intestinal microbiota in hydrocortisone (HC)-induced immunosuppressed mice. The results revealed that RPPs could increase the thymus and spleen indices and number of white blood cells, promote the secretion level of cytokines (IL-2, IL-6, TNF-α, and INF-γ), repair the morphology of the spleen and thymus, and enhance the proliferation of T-lymphocyte subsets in immunosuppressed mice. Moreover, RPPs improved the abundance of beneficial bacteria and preserved the ecological equilibrium of the gut microbiota. In conclusion, RPPs have significant immunomodulatory effects on immunosuppressed mice and may be developed as immunomodulators or immune adjuvants in functional foods and drugs; they are also beneficial to the utilization of the high value of marine shellfish.

Transcriptome Analysis Reveals the Immunoregulatory Activity of Rice Seed-Derived Peptide PEP1 on Dendritic Cells

Some food-derived bioactive peptides exhibit prominent immunoregulatory activity. We previously demonstrated that the rice-derived PEP1 peptide, GIAASPFLQSAAFQLR, has strong immunological activity. However, the mechanism of this action is still unclear. In the present study, full-length transcripts of mouse dendritic cells (DC2.4) treated with PEP1 were sequenced using the PacBio sequencing platform, and the transcriptomes were compared via RNA sequencing (RNA-Seq). The characteristic markers of mature DCs, the cluster of differentiation CD86, and the major histocompatibility complex (MHC-II), were significantly upregulated after the PEP1 treatment. The molecular docking suggested that hydrogen bonding and electrostatic interactions played important roles in the binding between PEP1, MHC-II, and the T-cell receptor (TCR). In addition, the PEP1 peptide increased the release of anti-inflammatory factors (interleukin-4 and interleukin-10) and decreased the release of pro-inflammatory factors (interleukin-6 and tumor necrosis factor-α). Furthermore, the RNA-seq results showed the expression of genes involved in several signaling pathways, such as the NF-κB, MAPK, JAK-STAT, and TGF-β pathways, were regulated by the PEP1 treatment, and the changes confirmed the immunomodulatory effect of PEP1 on DC2.4 cells. This findings revealed that the PEP1 peptide, derived from the byproduct of rice processing, is a potential natural immunoregulatory alternative for the treatment of inflammation.

Effects of Low Molecular Weight Peptides from Red Shrimp (Solenocera crassicornis) Head on Immune Response in Immunosuppressed Mice

This study aimed to investigate the immunoenhancement effects of low molecular weight peptides (SCHPs-F1) from red shrimp (Solenocera crassicornis) head against cyclophosphamide (CTX)-induced immunosuppressed mice. ICR mice were intraperitoneally injected with 80 mg/kg CTX for 5 consecutive days to establish the immunosuppressive model and then intragastrically administered with SCHPs-F1 (100 mg/kg, 200 mg/kg, and 400 mg/kg) to investigate its improving effect on immunosuppressed mice and explore its potential mechanism using Western blot. SCHPs-F1 could effectively improve the spleen and thymus index, promoting serum cytokines and immunoglobulins production and upregulating the proliferative activity of splenic lymphocytes and peritoneal macrophages of the CTX-treated mice. Moreover, SCHPs-F1 could significantly promote the expression levels of related proteins in the NF-κB and MAPK pathways in the spleen tissues. Overall, the results suggested that SCHPs-F1 could effectively ameliorate the immune deficiency caused by CTX and had the potential to explore as an immunomodulator in functional foods or dietary supplements.

Anti-Inflammation and Anti-Melanogenic Effects of Maca Root Extracts Fermented Using Lactobacillus Strains

Maca is a well-known biennial herb with various physiological properties, such as antioxidant activity and immune response regulation. In this study, the antioxidant, anti-inflammatory, and anti-melanogenic effects of fermented maca root extracts were investigated. The fermentation was carried out using Lactobacillus strains, such as Lactiplantibacillus plantarum subsp. plantarum, Lacticaseibacillus rhamnosus, Lacticaseibacillus casei, and Lactobacillus gasseri. In RAW 264.7 cells, the non-fermented maca root extracts increased the secretion of nitric oxide (NO), an inflammatory mediator, in a dose-dependent manner. In contrast, the fermented extracts showed considerably lower NO secretion than the non-fermented extracts at concentrations of 5% and 10%. This indicates the effective anti-inflammatory effects of fermented maca. The fermented maca root extracts also inhibited tyrosinase activity, melanin synthesis, and melanogenesis by suppressing MITF-related mechanisms. These results show that fermented maca root extracts exhibit higher anti-inflammatory and anti-melanogenesis effects than non-fermented maca root extracts. Thus, maca root extracts fermented using Lactobacillus strains have the potential to be used as an effective cosmeceutical raw material.

Phenolic Acid-Amino Acid Adducts Exert Distinct Immunomodulatory Effects in Macrophages Compared to Parent Phenolic Acids

Caffeic acid (CA) and chlorogenic acid (CGA) are commonly found phenolic acids in plant-derived foods and beverages. Their corresponding adducts with cysteine (Cys) have been detected in coffee-containing beverages. However, despite the well-documented antioxidant and anti-inflammatory activity of CA and CGA, the immunomodulatory activities of the Cys adducts (CA-Cys and CGA-Cys) are unknown. The adducts were therefore synthesized, and their immunomodulatory effects were studied in lipopolysaccharide (LPS)-treated RAW 264.7 cells and compared to the activity of the parent phenolic acids. CA and CGA generally down-regulated the inflammatory responses. However, RNA-sequencing showed that the LPS-induced pathways related to Toll-like receptor signaling, chemokine signaling, and NOD-like receptor signaling, and JAK-STAT/MAPK signaling pathways were upregulated in adduct-treated cells relative to parent phenolic acids, while neurodegenerative disorder-related pathways and metabolic pathways were downregulated. Production of prostaglandin E₂ (PGE₂), interleukin-6, tumor necrosis factor-α (TNF-α), and reactive oxygen species (ROS) was all inhibited by CA and CGA (P < 0.05). PGE₂ and TNF-α were further suppressed in adduct-stimulated cells (P < 0.05), but ROS production was increased. For example, TNF-α produced by 100 μM CGA-stimulated cells and 100 μM CGA-Cys adduct-stimulated cells were 4.46 ± 0.23 and 1.61 ± 0.18 ng/mL, respectively. Thus, the addition of the Cys moiety drastically alters the anti-inflammatory activity of phenolic compounds.

Purification, Identification and Molecular Docking of Immunomodulatory Peptides from the Heads of Litopenaeus vannamei

In order to realize the high-value utilization of Litopenaeus vannamei (L. vannamei) heads, immunomodulatory peptides were prepared from the enzymatic hydrolysate of L. vannamei heads, and the action mechanism of immunomodulatory peptides was determined by molecular docking. The results showed that six proteases were used to hydrolyze L. vannamei head proteins, with the animal protease hydrolysate exhibiting the highest macrophage relative proliferation rate (MRPR). The enzymatic products were then sequentially purified by ultrafiltration, Sephadex G-15 gel chromatography, identified by liquid chromatography-mass spectrometry (LC-MS/MS), and finally selected for six immunomodulatory peptides (PSPFPYFT, SAGFPEGF, GPQGPPGH, QGF, PGMR, and WQR). These peptides maintained good immune activity under heat treatment, pH treatment, and in vitro gastrointestinal digestion. Molecular docking analysis indicated that these peptides showed great binding to both toll-like receptor 2 and 4 (TLR2 and TLR4/MD-2), leading to immunomodulation. The discarded L. vannamei heads in this article are considered to be promising food-borne immunomodulators that contribute to enhancing the immune function of the body.

Immunoenhancing Effects of Cyclina sinensis Pentadecapeptide through Modulation of Signaling Pathways in Mice with Cyclophosphamide-Induced Immunosuppression

Our study aimed to investigate the immune-enhancing mechanism of the pentadecapeptide (RVAPEEHPVEGRYLV) from Cyclina sinensis (SCSP) in a cyclophosphamide (CTX)-induced murine model of immunosuppression. Our results showed that SCSP treatment significantly increased mouse body weight, immune organ indices, and the production of serum IL-6, IL-1β, and tumor necrosis factor (TNF)-α in CTX-treated mice. In addition, SCSP treatment enhanced the proliferation of splenic lymphocytes and peritoneal macrophages, as well as phagocytosis of the latter in a dose-dependent manner. Moreover, SCSP elevated the phosphorylation levels of p38, ERK, JNK, PI3K and Akt, and up-regulated IKKα, IKKβ, p50 NF-κB and p65 NF-κB protein levels, while down-regulating IκBα protein levels. Our results indicate that SCSP has immune-enhancing activities, and that it can activate the MAPK/NF-κB and PI3K/Akt pathways to enhance immunity in CTX-induced immunosuppressed mice.