Housefly Pupae-Derived Antioxidant Peptides Exerting Neuroprotective Effects on Hydrogen Peroxide-Induced Oxidative Damage in PC12 Cells

Curcumin nanoparticles in heat stroke management

OBJECTIVE

The exacerbation of extreme high-temperature events due to global climate change poses a significant challenge to public health, particularly impacting the central nervous system through heat stroke. This study aims to develop Poly(amidoamine) (PAMAM) nanoparticles loaded with curcumin (PAMAM@Cur) to enhance its therapeutic efficacy in hypothalamic neural damage in a heat stroke model and explore its potential mechanisms.

METHODS

Curcumin (Cur) was encapsulated into PAMAM nanoparticles through a hydrophobic interaction method, and various techniques were employed to characterize their physicochemical properties. A heat stroke mouse model was established to monitor body temperature and serum biochemical parameters, conduct behavioral assessments, histological examinations, and biochemical analyses. Transcriptomic and proteomic analyses were performed to investigate the therapeutic mechanisms of PAMAM@Cur, validated in an N2a cell model.

RESULTS

PAMAM@Cur demonstrated good stability, photostability, cell compatibility, significant blood-brain barrier (BBB) penetration capability, and effective accumulation in the brain. PAMAM@Cur markedly improved behavioral performance and neural cell structural integrity in heat stroke mice, alleviated inflammatory responses, with superior therapeutic effects compared to Cur or PAMAM alone. Multi-omics analysis revealed that PAMAM@Cur regulated antioxidant defense genes and iron death-related genes, particularly upregulating the PCBP2 protein, stabilizing SLC7A11 and GPX4 mRNA, and reducing iron-dependent cell death.

CONCLUSION

By enhancing the drug delivery properties of Cur and modulating molecular pathways relevant to disease treatment, PAMAM@Cur significantly enhances the therapeutic effects against hypothalamic neural damage induced by heat stroke, showcasing the potential of nanotechnology in improving traditional drug efficacy and providing new strategies for future clinical applications.

SIGNIFICANCE

This study highlights the outlook of nanotechnology in treating neurological disorders caused by heat stroke, offering a novel therapeutic approach with potential clinical applications.

Insect-derived extracts and peptides in neuroprotection

Throughout history, various cultures have recognized the significance of insects and have integrated them into traditional medicinal practices. In addition to medicines, insects are garnering attention as a sustainable and nutritious dietary alternative. Although edible insects have long been recognized as food sources in many Asian cultures, recent scientific studies have highlighted their potential therapeutic benefits, particularly in the field of neuroprotection. This review explores insect-derived extracts and peptides, elucidating their neuroprotective potential. This review highlights the potential use of insects as a source of neuroprotective agents. Advancements in neuroprotection may find a key ally in insects as our understanding of the symbiotic relationship between insects and human health becomes more profound.

Characterization and molecular docking of tetrapeptides with cellular antioxidant and ACE inhibitory properties from cricket (Acheta domesticus) protein hydrolysate

Wide-ranging bioactivities of enzymatically digested insect protein to produce peptides have been targeted for functional food development. In this study, fractionated peptides obtained from cricket (Acheta domesticus) protein hydrolysate by alcalase digestion were identified and evaluated for their bioactivities. Peptide fractions F44, F45, and F46, isolated through size exclusion chromatography, demonstrated strong cytoprotective effects on SH-SY5Y and HepG2 cells exposed to H2O2. This was evidenced by a 2-fold decrease in reactive oxygen species (ROS) accumulation in the cells and a 3-fold upregulation of genes encoding antioxidant enzymes. The F45 peptide fractions also showed chemical antioxidant activities ranging from approximately 290 to 393 mg trolox/g peptide, measured by DPPH, ABTS, and FRAP assays. Furthermore, F45 demonstrated the highest angiotensin-converting enzyme I (ACE) inhibitory activity, 57.93 %. F45 induced higher levels of Nrf2, SOD1, SOD2, CAT, GSR, and GPx4 gene expression in SH-SY5Y and HepG2 cells compared to cells treated with H2O2 and no peptides (p < 0.05). Cells treated with H2O2 and F45 exhibited significantly increased antioxidant enzyme activity, including SOD, CAT, GSR, and GPx (p < 0.05). The F45B fraction from F45 was sequenced to obtain FVEG and FYDQ tetrapeptides. Molecular docking analysis revealed their high binding affinity to cellular antioxidant enzymes (SOD, CAT, GSR, GPx1, and GPx4), an antioxidant-related protein (Keap1), and ACE. These results suggest that the novel tetrapeptides from Acheta domesticus demonstrate important biological activities, establishing them as significant cellular antioxidant activities and a potential source of antihypertensive peptides.

Alterations in the sequence and bioactivity of food-derived oligopeptides during simulated gastrointestinal digestion and absorption: a review

Food-derived oligopeptides (FOPs) exhibit various bioactivities. However, little was known about their sequence changes in the gastrointestinal tract and the effect of changes on bioactivities. FOPs' sequence features, changes and effects on bioactivities have been summarised. The sequence length of FOPs decreases with increased exposure of hydrophobic and basic amino acids at the terminal during simulated gastrointestinal digestion. A decrease in bioactivities after simulated intestinal absorption has correlated with a decrease of Leu, Ile, Arg, Tyr, Gln and Pro. The sequence of FOPs that pass readily through the intestinal epithelium corresponds to transport modes, and FOPs whose sequences remain unchanged after transport are the most bioactive. These include mainly dipeptides to tetrapeptides, consisting of numerous hydrophobic and basic amino acids, found mostly at the end of the peptide chain, especially at the C-terminal. This review aims to provide a foundation for applications of FOPs in nutritional supplements and functional foods.

Edible Insects as a Novel Source of Bioactive Peptides: A Systematic Review

The production of food and feed to meet the needs of the growing world's population will soon become a serious challenge. In search for sustainable solutions, entomophagy is being proposed as an alternative source of proteins, with economic and environmental advantages when compared to meat. Edible insects are not only a valuable source of important nutrients, but their gastrointestinal digestion also originates small peptides with important bioactive properties. The present work intends to provide an exhaustive systematic review on research articles reporting bioactive peptides identified from edible insects, as demonstrated by in silico, in vitro, and/or in vivo assays. A total of 36 studies were identified following the PRISMA methodology, gathering 211 potentially bioactive peptides with antioxidant, antihypertensive, antidiabetic, antiobesity, anti-inflammatory, hypocholesterolemia, antimicrobial, anti-severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), antithrombotic, and immunomodulatory properties, originated from the hydrolysates of 12 different insect species. From these candidates, the bioactive properties of 62 peptides were characterized in vitro and 3 peptides were validated in vivo. Data establishing the scientific basis of the health benefits associated with the consumption of edible insects can be a valuable contribution to overcoming the cultural issues that hinder the introduction of insects in the Western diet.

Novel N1 or N9 modified α-carboline analogues as potential ligands in Alzheimer's disease therapy: Synthesis and neurobiological activity evaluation

A series of new α-carboline analogues modified at N¹ or N⁹ positions by alkyl, benzyl and phenyl were synthesized and characterized as potential ligands for AD therapy. These compounds exhibited multifunctional neurobiological activities including anti-neuroinflammatory, neuroprotective and cholinesterase inhibition. Among them, compound 5d with good drug-like properties and no cytotoxicity, showed potent inhibitory activity against NO production (IC₅₀ = 1.45 μM), which could suppress the expression levels of iNOS and COX-2 in a dose-dependent manner. Further mechanism exploration indicated that compound 5d could regulate the NF-κB signaling pathway by decreasing the phosphorylation of IκB-α and p65. Notably, compound 5d could effectively decrease the LPS-induced aberrations in zebrafish. Compounds 3b, 4f, 5c, 5g, 5m and 6i exhibited potential neuroprotective activity (cell viability > 70 %) in the H₂O₂-induced PC-12 neuronal death model and rescued the SOD activity. In particular, compounds 3b, 4f, and 5g activated the Nrf2 signaling pathway, and improved the expressions of antioxidant proteins NQO-1 and HO-1, which alleviated the head cell apoptosis in zebrafish. Additionally, compound 6i exhibited potential inhibitory activity against BuChE with IC₅₀ of 0.77 μM. Overall, this work provided some lead compounds based on α-carboline used for AD therapy.

Structure-activity relationship of a housefly neuroprotective dodecapeptide that activates the nuclear factor erythroid 2-related factor 2 pathway

Neuroprotective antioxidants, especially peptide-based antioxidants, are effective against oxidative stress in neurodegenerative disorders. In this study, we measured the neuroprotective effects of the antioxidant peptide DFTPVCTTELGR (DR12) from housefly Musca domestica L. pupae. Treatment of PC12 and HT22 cells with DR12 significantly reduced glutamate-induced cytotoxicity. Peptide DR12 appeared to exert its neuroprotective effects by attenuating production of reactive oxygen species and malonaldehyde, upregulating the endogenous antioxidants superoxide dismutase and glutathione, and reversing the loss of mitochondrial membrane potential. In addition, DR12 treatment activated the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 signaling pathway. Structure-activity analysis indicated that the superior neuroprotective function of DR12 was related to its cysteine residue. In summary, DR12 may be an attractive therapeutic peptide or precursor to treat neurodegenerative diseases.

Piperine Derived from Piper nigrum L. Inhibits LPS-Induced Inflammatory through the MAPK and NF-κB Signalling Pathways in RAW264.7 Cells

Piperine, an important natural product, has a good anti-inflammatory effect. However, few researchers have studied its mechanism in these pathways. The objective of this research was to evaluate the molecular mechanism underlying the anti-inflammatory responses of piperine in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The purification and characterization of piperine from Piper nigrum L. were determined by HPLC, UPLC-Q-TOF-MS and ¹H NMR. Then, the anti-inflammatory activity was evaluated by a reagent test kit, ELISA kits, RT-PCR and Western blot experiments. The results suggested that piperine (90.65 ± 0.46% purity) at a concentration of 10–20 mg/L attenuated the production of NO and ROS, downregulated the protein and mRNA expression levels of TNF-α, IL-1β and IL-6, and upregulated the protein and mRNA transcription levels of IL-10. Meanwhile, the Western blot results indicated that piperine could inhibit the phosphorylation levels of the ERK, JNK, p38 and p65 proteins. Our findings suggest that piperine is a potential anti-inflammatory substance, whose molecular mechanism may be to regulate the key factors of the NF-κB and MAPK signalling pathways.

Nanozymes Regulate Redox Homeostasis in ROS-Related Inflammation

Reactive oxygen species (ROS), in moderate amounts, play an essential role in regulating different physiological functions in organisms. However, increased amounts of ROS may cause oxidative stress and damage to biomolecules, leading to a variety of diseases including inflammation and even cancer. Therefore, ROS scavenging reagents are needed to maintain healthy levels of ROS. With considerable advances in nanotechnology, nanozymes possess SOD or CAT-like activities with outstanding free radical scavenging activity, facile synthesis conditions, and excellent biocompatibility. Based on these extraordinary properties, nanozymes has been used to modulate the redox homeostasis and relieve the ROS-related injury. This has led to the emergence of nanozyme-based therapies. In the current review, we presented recently developed applications of nanozymes to treat ROS-dependent disorders with an emphasis on inflammatory and brain diseases.

Antioxidant activity of SSeCAHK in HepG2 cells: a selenopeptide identified from selenium-enriched soybean protein hydrolysates

This paper is aimed at purifying and identifying selenium (Se)-containing antioxidative peptides from Se-enriched soybean peptides (SSP). In this work, the SSP was separated into five fractions (F1 to F5). Fraction F4, displaying the highest antioxidative activity, was further separated, and sub-fractions F4-1 to F4-5 were selected for antioxidative activity evaluation using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis-(3-ethylbenzo-thiazoline-6-sulphonic acid)diammonium salt (ABTS), and OH- radical scavenging assays. The Se-containing antioxidative peptides with sequence Ser-SeC-Ala-His-Lys (SSeCAHK) were identified in sub-fraction F4-1 and chemically synthesized. This Se-containing pentapeptide showed a preventive effect against hydrogen peroxide (H2O2)-induced oxidative stress in HepG2 cells. Pretreating the cells for 2 h with SSeCAHK (0.13-0.50 mg mL-1) induced strong intracellular, reactive oxygen species (ROS) scavenging activity while preventing a decrease in reduced glutathione (GSH) and an increase in malondialdehyde (MDA). Therefore, SSeCAHK treatment improved H2O2-induced oxidative stress in HepG2 cells, demonstrating the significant potential of SSeCAHK as a natural antioxidative functional material for dietary supplementation.

Hydrolase-Treated Royal Jelly Attenuates H2O2- and Glutamate-Induced SH-SY5Y Cell Damage and Promotes Cognitive Enhancement in a Rat Model of Vascular Dementia

Vascular dementia (VaD) is the second most common type of dementia following Alzheimer's disease, but the therapeutic efficacy is still not effective. This makes the searching for novel neuroprotective agents important. Therefore, we hypothesized that royal jelly, a well-known traditional medicine, could attenuate memory impairment and brain damage in vascular dementia. This study determined the effects of royal jelly hydrolysate (RJH) and possible mechanism of cell damage and cognitive-enhancing effect in animal study. An in vitro study assessed the effects of RJH on acetylcholinesterase inhibitor, cell viability, and cell damage in SH-SY5Y neuroblastoma cells. Then, an in vivo study examined vascular dementia by the occlusion of the right middle cerebral artery (Rt.MCAO); adult male Wistar rats had been orally given RJH at doses ranging from 10, 50, to 100 mg/kg for 14 days before and 14 days after the occlusion of Rt.MCAO to mimic the VaD condition. Rats' spatial memory was evaluated using Morris water maze and radial arm maze every 7 days after Rt.MCAO throughout a 14-day experimental period, and then, they were sacrificed and the acetylcholinesterase (AChE) activity in the hippocampus was determined. The results showed that RJH has no cytotoxic effect with the final concentration up to 500 μg protein/ml and reduces cell death from the H₂O₂- and glutamate-induced cell damage in in vitro neuroblastoma cells. Importantly, RJH significantly improved memory performance in Morris water maze test and radial arm maze and decreased the level of acetyl cholinesterase activity. In conclusion, RJH is the potential neuroprotective agent and cognitive enhancer for VaD.

Novel neuroprotective peptides in the venom of the solitary scoliid wasp Scolia decorata ventralis

Background

Solitary wasp venoms may be a rich source of neuroactive substances, since their venoms are used for paralyzing preys. We have been exploring bioactive constituents of solitary wasp venoms and, in this study, the component profile of the venom from a solitary scoliid wasp, Scolia decorata ventralis, was investigated through a comprehensive analysis using LC-MS. Two peptides were synthesized, and their neuroprotective properties were evaluated.

Methods

A reverse-phase HPLC connected to ESI-MS was used for LC-MS analyses. Online mass fingerprinting was performed from TIC, and data-dependent tandem mass spectrometry gave the MS/MS spectra. The sequences of two major peptide components were determined by MALDI-TOF/TOF MS analysis, confirmed by solid phase synthesis. Using the synthetic peptides, biological activities were assessed. Cell integrity tests and neuroprotection analyzes using H₂O₂ as an oxidative stress inducer were performed for both peptides.

Results

Online mass fingerprinting revealed that the venom contains 123 components, and the MS/MS analysis resulted in 33 full sequences of peptide components. The two main peptides, α-scoliidine (DYVTVKGFSPLR) and β-scoliidine (DYVTVKGFSPLRKA), present homology with the bradykinin C-terminal. Despite this, both peptides did not behave as substrates or inhibitors of ACE, indicating that they do not interact with this metallopeptidase. In further studies, β-scoliidine, but not α -scoliidine, showed protective effects against oxidative stress-induced neurotoxicity in PC12 cells through integrity and metabolism cell assays. Interestingly, β-scoliidine has the extension of the KA dipeptide at the C-terminal in comparison with α-scoliidine.

Conclusion

Comprehensive LC-MS and MS/MS analyses from the Scolia decorata ventralis venom displayed the component profile of this venom. β-scoliidine showed an effective cytoprotective effect, probably due to the observed increase in the number of cells. This is the first report of solitary wasp venom peptides showing neuroprotective activity.

Use of Alcalase in the production of bioactive peptides: A review

This review aims to cover the uses of the commercially available protease Alcalase in the production of biologically active peptides since 2010. Immobilization of Alcalase has also been reviewed, as immobilization of the enzyme may improve the final reaction design enabling the use of more drastic conditions and the reuse of the biocatalyst. That way, this review presents the production, via Alcalase hydrolysis of different proteins, of peptides with antioxidant, angiotensin I-converting enzyme inhibitory, metal binding, antidiabetic, anti-inflammatory and antimicrobial activities (among other bioactivities) and peptides that improve the functional, sensory and nutritional properties of foods. Alcalase has proved to be among the most efficient proteases for this goal, using different protein sources, being especially interesting the use of the protein residues from food industry as feedstock, as this also solves nature pollution problems. Very interestingly, the bioactivities of the protein hydrolysates further improved when Alcalase is used in a combined way with other proteases both in a sequential way or in a simultaneous hydrolysis (something that could be related to the concept of combi-enzymes), as the combination of proteases with different selectivities and specificities enable the production of a larger amount of peptides and of a smaller size.