Potential anti-inflammatory activity of walnut protein derived peptide leucine-proline-phenylalanine in lipopolysaccharides-irritated RAW264.7 cells

Promising protective treatment potential of endophytic bacterium Rhizobium aegyptiacum for ulcerative colitis in rats

Ulcerative colitis (UC) is an inflammatory condition of the intestine, resulting from an increase in oxidative stress and pro-inflammatory mediators. In this study, the extract of endophytic bacterium Rhizobium aegyptiacum was prepared for the first time using liquid chromatography-mass spectrometry (LC-MS). In addition, also for the first time, the protective potential of R. aegyptiacum was revealed using an in vivo rat model of UC. The animals were grouped into four categories: normal control (group I), R. aegyptiacum (group II), acetic acid (AA)‍-induced UC (group III), and R. aegyptiacum-treated AA-induced UC (group IV). In group IV, R. aegyptiacum was administered at 0.2 mg/kg daily for one week before and two weeks after the induction of UC. After sacrificing the rats on the last day of the experiment, colon tissues were collected and subjected to histological, immunohistochemical, and biochemical investigations. There was a remarkable improvement in the histological findings of the colon tissues in group IV, as revealed by hematoxylin and eosin (H&E) staining, Masson's trichrome staining, and periodic acid-Schiff (PAS) staining. Normal mucosal surfaces covered with a straight, intact, and thin brush border were revealed. Goblet cells appeared magenta in color, and there was a significant decrease in the distribution of collagen fibers in the mucosa and submucosal connective tissues. All these findings were comparable to the respective characteristics of the control group. Regarding cyclooxygenase-2 (COX-2) immunostaining, a weak immune reaction was shown in most cells. Moreover, the colon tissues were examined using a scanning electron microscope, which confirmed the results of histological assessment. A regular polygonal unit pattern was seen with crypt orifices of different sizes and numerous goblet cells. Furthermore, the levels of catalase (CAT), myeloperoxidase (MPO), nitric oxide (NO), interleukin-6 (IL-6), and interlukin-1β (IL-1β) were determined in the colonic tissues of the different groups using colorimetric assay and enzyme-linked immunosorbent assay (ELISA). In comparison with group III, group IV exhibited a significant rise (P<0.05) in the CAT level but a substantial decline (P<0.05) in the NO, MPO, and inflammatory cytokine (IL-6 and IL-1β) levels. Based on reverse transcription-quantitative polymerase chain reaction (RT-qPCR), the tumor necrosis factor-‍α (TNF-‍α) gene expression was upregulated in group III, which was significantly downregulated (P<0.05) by treatment with R. aegyptiacum in group IV. On the contrary, the heme oxygenase-1 (HO-1) gene was substantially upregulated in group IV. Our findings imply that the oral consumption of R. aegyptiacum ameliorates AA-induced UC in rats by restoring and reestablishing the mucosal integrity, in addition to its anti-oxidant and anti-inflammatory effects. Accordingly, R. aegyptiacum is potentially effective and beneficial in human UC therapy, which needs to be further investigated in future work.

Regulation of Intestinal Inflammation by Walnut-Derived Bioactive Compounds

Walnuts (Juglans regia L.) have shown promising effects in terms of ameliorating inflammatory bowel disease (IBD), attributed to their abundant bioactive compounds. This review comprehensively illustrates the key mechanisms underlying the therapeutic potential of walnuts in IBD management, including the modulation of intestinal mucosa permeability, the regulation of inflammatory pathways (such as NF-kB, COX/COX2, MAPCK/MAPK, and iNOS/NOS), relieving oxidative stress, and the modulation of gut microbiota. Furthermore, we highlight walnut-derived anti-inflammatory compounds, such as polyunsaturated fatty acids (PUFA; e.g., ω-3 PUFA), tocopherols, phytosterols, sphingolipids, phospholipids, phenolic compounds, flavonoids, and tannins. We also discuss unique anti-inflammatory compounds such as peptides and polysaccharides, including their extraction and preparation methods. Our review provides a theoretical foundation for dietary walnut supplementation in IBD management and provides guidance for academia and industry. In future, research should focus on the targeted isolation and purification of walnut-derived anti-inflammatory compounds or optimizing extraction methods to enhance their yields, thereby helping the food industry to develop dietary supplements or walnut-derived functional foods tailored for IBD patients.

Anti-inflammatory peptide therapeutics and the role of sulphur containing amino acids (cysteine and methionine) in inflammation suppression: A review

BACKGROUND

Inflammation serves as our body's immune response to combat infections, pathogens, viruses, and external stimuli. Inflammation can be classified into two types: acute inflammation and chronic inflammation. Non-steroidal anti-inflammatory medications (NSAIDs) are used to treat both acute and chronic inflammatory disorders. However, these treatments have various side effects such as reduced healing efficiency, peptic ulcers, gastrointestinal toxicities, etc. METHOD: This review assesses the potential of anti-inflammatory peptides (AIPs) derived from various natural sources, such as algae, fungi, plants, animals, and marine organisms. Focusing on peptides rich in cysteines and methionine, sulphur-containing amino acids known for their role in suppression of inflammation.

RESULT

Due to their varied biological activity, ability to penetrate cells, and low cytotoxicity, bioactive peptides have garnered interest as possible therapeutic agents. The utilisation of AIPs has shown great potential in the treatment of disorders associated with inflammation. AIPs can be obtained from diverse natural sources such as algae, fungi, plants, and animals. Cysteine and methionine are sulphur-containing amino acids that aid in the elimination of free radicals, hence assisting in the treatment of inflammatory diseases.

CONCLUSION

This review specifically examines several sources of AIPs including peptides that contain numerous cysteines and methionine. In addition, the biological characteristics of these amino acids and advancements in peptide delivery are also discussed.

Walnut Protein Peptides Ameliorate DSS-Induced Ulcerative Colitis Damage in Mice: An in Silico Analysis and in Vivo Investigation

Walnut (Juglans regia L.) is a food with food-medicine homology, whose derived protein peptides have been shown to have anti-inflammatory activity in vitro. However, the effects and mechanisms of walnut protein peptides on ulcerative colitis (UC) in vivo have not been systematically and thoroughly investigated. In this study, we applied virtual screening and network pharmacology screening of bioactive peptides to obtain three novel WPPs (SHTLP, HYNLN, and LGTYP) that may alleviate UC through TLR4-MAPK signaling. In vivo studies have shown that WPPs improve intestinal mucosal barrier dysfunction and reduce inflammation by inhibiting activation of the TLR4-MAPK pathway. In addition, WPPs restore intestinal microbial homeostasis by reducing harmful bacteria (Helicobacter and Bacteroides) and increasing the relative abundance of beneficial bacteria (Candidatus_Saccharimonas). Our study showed that the WPPs obtained by virtual screening were effective in ameliorating colitis, which has important implications for future screening of bioactive peptides from medicinal food homologues as drugs or dietary supplements.

Isolation, Identification, Activity Evaluation, and Mechanism of Action of Neuroprotective Peptides from Walnuts: A Review

As human life expectancy increases, the incidence of neurodegenerative diseases in older adults has increased in parallel. Walnuts contain bioactive peptides with demonstrated neuroprotective effects, making them a valuable addition to the diet. We here present a comprehensive review of the various methods used to prepare, isolate, purify, and identify the neuroprotective peptides found in walnuts. We further summarise the different approaches currently used to evaluate the activity of these peptides in experimental settings, highlighting their potential to reduce oxidative stress, neuroinflammation, and promote autophagy, as well as to regulate the gut microflora and balance the cholinergic system. Finally, we offer suggestions for future research concerning bioavailability and improving or masking the bitter taste and sensory properties of final products containing the identified walnut neuroprotective peptides to ensure successful adoption of these peptides as functional food ingredients for neurohealth promotion.

Walnut Protein: A Rising Source of High-Quality Protein and Its Updated Comprehensive Review

Recently, plant protein as a necessary nutrient source for human beings, a common ingredient of traditional processed food, and an important element of new functional food has gained prominence due to the increasing demand for healthy food. Walnut protein (WP) is obtained from walnut kernels and walnut oil-pressing waste and has better nutritional, functional, and essential amino acids in comparison with other vegetable and grain proteins. WP can be conveniently obtained by various extraction techniques, including alkali-soluble acid precipitation, salting-out, and ultrasonic-assisted extraction, among others. The functional properties of WP can be modified for desired purposes by using some novel methods, including free radical oxidation, enzymatic modification, high hydrostatic pressure, etc. Moreover, walnut peptides play an important biological role both in vitro and in vivo. The main activities of the walnut peptides are antihypertensive, antioxidant, learning improvement, and anticancer, among others. Furthermore, WP could be applied in the development of functional foods or dietary supplements, such as delivery systems and food additives, among others. This review summarizes recent knowledge on the nutritional, functional, and bioactive peptide aspects of WP and possible future products, providing a theoretical reference for the utilization and development of oil crop waste.

Prevention and potential repair of colitis: Beneficial effects and regulatory mechanisms of food-derived anti-inflammatory peptides

Intestinal inflammatory diseases are increasingly prevalent worldwide, and their pathogenesis is still not fully understood. As of late, studies have discovered that food-derived peptides have specific anti-inflammatory activity and can play a positive role in intestinal health. At the same time, it has broad application prospects in the prevention and treatment of colitis because of its wide source, fast absorption, and high safety. This article reviews the structure-activity and quantity-effect relationships of food-derived peptides for their anti-inflammatory effects. It then discusses their mechanism of action in inhibiting colitis from four aspects. Food-derived anti-inflammatory peptides can delay the progression of the disease by stimulating innate immunity, inhibiting inflammation, and promoting wound healing. Further experiments showed that food-derived anti-inflammatory peptides could prevent and treat colitis through four mechanisms: (a) regulation of inflammatory cytokines; (b) regulation of inflammatory pathways; (c) regulation of intestinal epithelial barrier; (d) regulation of intestinal flora balance. However, due to the treatment of colitis having limitations, there is an urgent to develop food-derived anti-inflammatory peptides as a treatment or adjunctive treatment for colitis. This review highlights the positive effects of food-derived peptides on colitis and anticipates the appearance of mitigating peptides for the therapy of colitis.

Recent Studies on Protective Effects of Walnuts against Neuroinflammation

Neuroinflammation plays a significant role in the aging process and the pathophysiology of neurodegenerative diseases, such as Alzheimer’s disease. Accordingly, possible therapeutic strategies aimed at anti-inflammatory effects may be beneficial to brain health. Walnut kernels contain large quantities of unsaturated fatty acids, peptides, and phenolic compounds that have anti-inflammatory effects. The long-term intake of walnuts has been found to improve cognitive function and memory in rats and humans. However, the modulatory effect of walnuts on neuroinflammation has received much less attention. This review focuses on the potential influence and main regulating mechanisms of walnuts and their active ingredients on neuroinflammation, including the regulation of microglia activation induced by amyloid β or lipopolysaccharides, inhibition of peripheral inflammation mediated by macrophages, reduction in oxidative stress by decreasing free radical levels and boosting antioxidant defenses, and control of gut microbes to maintain homeostasis. However, the majority of evidence of the beneficial effects of walnuts or their components on neuroinflammation and neurodegeneration comes from experimental work, whereas evidence from clinical studies on the beneficial effects is scarcer and less conclusive. This review aims to provide new insights into the neuroinflammation-regulating mechanisms and natural active ingredients of walnuts and the development of walnut-based functional foods for the alleviation of neurodegenerative diseases.

Anti-Inflammatory Function of Plant-Derived Bioactive Peptides: A Review

Inflammation is considered to be a crucial factor in the development of chronic diseases, eight of which were listed among the top ten causes of death worldwide in the World Health Organization’s World Health Statistics 2019. Moreover, traditional drugs for inflammation are often linked to undesirable side effects. As gentler alternatives to traditional anti-inflammatory drugs, plant-derived bioactive peptides have been shown to be effective interventions against various chronic diseases, including Alzheimer’s disease, cardiovascular disease and cancer. However, an adequate and systematic review of the structures and anti-inflammatory activities of plant-derived bioactive peptides has been lacking. This paper reviews the latest research on plant-derived anti-inflammatory peptides (PAPs), mainly including the specific regulatory mechanisms of PAPs; the structure–activity relationships of PAPs; and their enzymatic processing based on the structure–activity relationships. Moreover, current research problems for PAPs are discussed, such as the shallow exploration of mechanisms, enzymatic solution determination difficulty, low yield and unknown in vivo absorption and metabolism and proposed future research directions. This work aims to provide a reference for functional activity research, nutritional food development and the clinical applications of PAPs.