Hypotensive peptides derived from plant proteins

Study on Fermentation Preparation, Stability, and Angiotensin-Converting Enzyme Inhibitory Activity of Tomato Pomace Peptide

The substantial quantity of discarded tomato pomace (TP) results in the waste of valuable resources. This study utilizes these tomato by-products by mixing them with water in a specific proportion and fermenting the mixture in two stages: first with yeast, and then with lactic acid bacteria. The most suitable microbial strains for TP fermentation were identified by evaluating parameters such as peptide content, degree of hydrolysis, and gel electrophoresis analysis. Subsequently, tomato pomace peptides (TPPs) were separated into peptides of different molecular weights using ultrafiltration. The IC50 values, ACE inhibitory activities, and in vitro stability of these peptides were compared, and their secondary structures and microstructures were characterized. The results indicated that the soluble protein concentration increased from 26.25 mg/g to 39.03 mg/g after 32 h of fermentation with strain RV171. After an additional 32 h of fermentation with Bifidobacterium thermophilum, the peptide content reached 49.18 ± 0.43%. SDS-PAGE gel electrophoresis showed that the TPP molecular weights were predominantly below 10 kDa. The IC50 results demonstrated that fractions with smaller molecular weights exhibited greater ACE inhibitory activities. Structural analysis confirmed that the TP hydrolysate was indeed a peptide.

Oat-Protein-Based Diet Lowers Blood Pressure and Prevents Cardiac Remodeling and Dysfunction in Spontaneously Hypertensive Rats

Background/Objectives: Hypertension and its associated complications, such as cardiac remodeling and dysfunction, continue to impose a significant burden on global healthcare. Nutritional interventions have been recognized as playing a crucial role in addressing this devastating condition termed a 'silent killer'. Plant-based proteins could potentially be utilized as a non-pharmacological strategy to combat hypertension and its related risk factors. In this study, we investigated the efficacy of an oat protein diet in managing hypertension and cardiac abnormalities. Methods: Four-week-old male spontaneously hypertensive rats (SHRs) and Wistar-Kyoto (WKY) rats were fed a regular diet with casein as a protein source or an oat-protein-based diet for 16 weeks. Twenty-week-old male SHRs showed high blood pressure (BP), cardiac remodeling, cardiac dysfunction, higher levels of markers of oxidative stress [malondialdehyde (MDA)] and inflammation [tumor necrosis factor-α (TNF-α)], as well as lower levels of a marker of vascular function (nitric oxide). Results: The oat protein diet was able to significantly lower high BP, prevent cardiac remodeling and dysfunction, improve the levels of nitric oxide, and reduce the levels of TNF-α. Oat protein, after in vitro gastrointestinal digestion, also exhibited angiotensin-converting enzyme inhibition and significantly higher antioxidant activity than casein when assessed with the 2,2-diphenyl-1-picrylhydrazyl and the iron-chelating assays in vitro.Conclusions: oat protein lowers BP and prevents cardiac remodeling and dysfunction partly via improving the levels of nitric oxide and TNF-αin SHRs. Its high antioxidant potential could contribute to the observed cardiovascular effects.

Rice proteins: A review of their extraction, modification techniques and applications

Rice protein is highly nutritious and easy to digest and absorb. Its hydrolyzed peptides have significant effects on lowering blood pressure and cholesterol. First, a detailed and comprehensive explanation of rice protein extraction methods was given, and it was found that the combination of enzymatic and physical methods could improve the extraction rate of rice protein, but it was only suitable for laboratory studies. Second, the methods for improving the functional properties of rice protein were introduced, including physical modification, chemical modification, and enzymatic modification. Enzymatic modification of the solubility of rice protein to improve its functional properties has certain limitations due to the low degree of hydrolysis, the long time required, the low utilization of the enzyme, and the possible undesirable taste of the product. Finally, the development and utilization of rice protein was summarized and the future research direction was suggested. This paper lists the advantages and disadvantages of various extraction techniques, points out the shortcomings of existing extraction techniques, aims to fill the gap in the field of rice protein extraction, and then provides a possible improvement method for the extraction and development of rice protein in the future.

A Review of Bioactive Compound Effects from Primary Legume Protein Sources in Human and Animal Health

The global demand for sustainable and nutritious food sources has catalyzed interest in legumes, known for their rich repertoire of health-promoting compounds. This review delves into the diverse array of bioactive peptides, protein subunits, isoflavones, antinutritional factors, and saponins found in the primary legume protein sources-soybeans, peas, chickpeas, and mung beans. The current state of research on these compounds is critically evaluated, with an emphasis on the potential health benefits, ranging from antioxidant and anticancer properties to the management of chronic diseases such as diabetes and hypertension. The extensively studied soybean is highlighted and the relatively unexplored potential of other legumes is also included, pointing to a significant, underutilized resource for developing health-enhancing foods. The review advocates for future interdisciplinary research to further unravel the mechanisms of action of these bioactive compounds and to explore their synergistic effects. The ultimate goal is to leverage the full spectrum of benefits offered by legumes, not only to advance human health but also to contribute to the sustainability of food systems. By providing a comprehensive overview of the nutraceutical potential of legumes, this manuscript sets a foundation for future investigations aimed at optimizing the use of legumes in the global pursuit of health and nutritional security.

In silico and in vivo experiment of soymilk peptide (tetrapeptide - FFYY) for the treatment of hypertension

Enzyme-Treated Soymilk (ETS) was produced from Commercial Soymilk (CSM) with the treatment of proteinase PROTIN SD-NY10 (Bacillus amyloliquefaciens). Previously, we have isolated novel peptides from ETS but data related to isolated-peptides are scant. In this study, bio-informatics and in vivo analysis of isolated-peptides showed strong binding affinity to the active site of the Angiotensin Converting Enzyme (ACE). Among four peptides, tetrapeptide Phe-Phe-Tyr-Tyr (FFYY) showed strong binding affinity and inhibitory activity to the ACE-enzyme (binding affinity -9.5 Kcal/mol and inhibitory concentration of 1.9 µM respectively) as well as showed less toxicity compared to other peptides. The animal experiment revealed that single oral dose of FFYY (80 µg/kg body weight/day) effectively ameliorates the systolic, diastolic and mean blood pressure in the spontaneously hypertensive rat (SHR) model. Chronic oral administration of FFYY (80 µg/kg body weight/day for 3 weeks) reduced the systolic blood pressure elevation and ACE activity without any adverse side effects on the physiological and biological parameters of SHR. In conclusion, both in silico and in vivo experiments of soymilk-isolated FFYY peptide showed a promising option as a potential alternative for hypertension treatment without adverse side effects on SHR.

A sensitive and specific LC-MS/MS method for determination of a novel antihypertensive peptide FR-6 in rat plasma and pharmacokinetic study

The investigation of peptide drugs has become essential in the development of innovative medications for hypertension. In this study, a sensitive high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method was developed to determine the plasma concentration and stability of the antihypertensive peptide FR-6 in rats. An isotopically labeled peptide (with an unchanged sequence) was utilized as an internal standard (IS) for validation purposes. Subsequently, this assay was employed to examine the pharmacokinetics of different administration methods (tail vein and gavage) in Sprague Dawley (SD) rats. Extracted plasma samples underwent sample preparation through methanol protein precipitation, followed by elution of FR-6 on Wondasil C18 Superb column (4.6 × 150 mm, 5 μm), using a mobile phase consisting of formic acid (0.1%) in water (A) and formic acid (0.125%)-ammonium formate (2 mM) in methanol (B). Ion pairs corresponding to FR-6 and IS were monitored via multiple reaction monitoring (MRM) under positive ion mode: m/z 400.7 → 285.1 for FR-6 and m/z 406.1 → 295.1 for IS detection respectively. The method exhibited excellent linearity with respect to FR-6 concentrations. In addition, the inter-day and intra-day precision were 0.61-6.85% and 1.76-11.75%; the inter-day and intra-day accuracy were -7.28-0.13% and -7.20-2.28%, respectively. In conclusion, the matrix effect, extraction recovery, and stability data were validated according to FDA recommended acceptance criteria for bioanalytical methods. This validated method serves as a reliable tool for determining the concentration of antihypertensive peptide FR-6, and has been successfully applied in pharmacokinetic studies involving rats.

Food-derived peptides as novel therapeutic strategies for NLRP3 inflammasome-related diseases: a systematic review

NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3), a member of the nucleotide-binding domain (NOD) and leucine-rich repeat sequence (LRR) protein (NLR) family, plays an essential role in the inflammation initiation and inflammatory mediator secretion, and thus is also associated with many disease progressions. Food-derived bioactive peptides (FDBP) exhibit excellent anti-inflammatory activity in both in vivo and in vitro models. They are encrypted in plant, meat, and milk proteins and can be released under enzymatic hydrolysis or fermentation conditions, thereby hindering the progression of hyperuricemia, inflammatory bowel disease, chronic liver disease, neurological disorders, lung injury and periodontitis by inactivating the NLRP3. However, there is a lack of systematic review around FDBP, NLRP3, and NLRP3-related diseases. Therefore, this review summarized FDBP that exert inhibiting effects on NLRP3 inflammasome from different protein sources and detailed their preparation and purification methods. Additionally, this paper also compiled the possible inhibitory mechanisms of FDBP on NLRP3 inflammasomes and its regulatory role in NLRP3 inflammasome-related diseases. Finally, the progress of cutting-edge technologies, including nanoparticle, computer-aided screening strategy and recombinant DNA technology, in the acquisition or encapsulation of NLRP3 inhibitory FDBP was discussed. This review provides a scientific basis for understanding the anti-inflammatory mechanism of FDBP through the regulation of the NLRP3 inflammasome and also provides guidance for the development of therapeutic adjuvants or functional foods enriched with these FDBP.

The Research Progress of Bioactive Peptides Derived from Traditional Natural Products in China

Traditional natural products in China have a long history and a vast pharmacological repertoire that has garnered significant attention due to their safety and efficacy in disease prevention and treatment. Among the bioactive components of traditional natural products in China, bioactive peptides (BPs) are specific protein fragments that have beneficial effects on human health. Despite many of the traditional natural products in China ingredients being rich in protein, BPs have not received sufficient attention as a critical factor influencing overall therapeutic efficacy. Therefore, the purpose of this review is to provide a comprehensive summary of the current methodologies for the preparation, isolation, and identification of BPs from traditional natural products in China and to classify the functions of discovered BPs. Insights from this review are expected to facilitate the development of targeted drugs and functional foods derived from traditional natural products in China in the future.

Screening potential hypertensive peptides using two consecutive bioassay-guided SPE fractionations and identification of an ACE inhibitory peptide, DHSTAVW (DW7), derived from pearl garlic protein hydrolysate

The pearl garlic (Allium sativum L.) protein (PGP) was digested using pepsin, trypsin, α-chymotrypsin, thermolysin, and simulated gastrointestinal digestion. The α-chymotrypsin hydrolysate showed the highest angiotensin-I-converting enzyme inhibitory (ACEI) activity, with an IC₅₀ value of 190.9 ± 11µg/mL. A reversed-phase C₁₈ solid-phase extraction (RP-SPE) cartridge was used for the first fractionation, and the S4 fraction from RP-SPE showed the most potent ACEI activity (IC₅₀ = 124.1 ± 11 3µg/mL). The S4 fraction was further fractionated using a hydrophilic interaction liquid chromatography SPE (HILIC-SPE). The H4 fraction from HILIC-SPE showed the highest ACEI activity (IC₅₀ = 57.7 ± 3µg/mL). Four ACEI peptides (DHSTAVW, KLAKVF, KLSTAASF, and KETPEAHVF) were identified from the H4 fraction using liquid chromatography-tandem mass spectrometry (LC-MS/MS), and their biological activities were appraised in silico. Among the identified α-chymotryptic peptides, DHSTAVW (DW7), derived from I lectin partial protein, exhibited the most potent ACEI activity (IC₅₀ value of 2.8 ± 0.1µM). DW7 was resistant to simulated gastrointestinal digestion, and it was classified as a prodrug-type inhibitor according to the preincubation experiment. The inhibition kinetics indicated that DW7 was a competitive inhibitor, which was rationalized by the molecular docking simulation. The quantities of DW7 in 1mg of hydrolysate, S4 fraction, and H4 fraction were quantified using LC-MS/MS to give 3.1 ± 0.1, 4.2 ± 0.1, and 13.2 ± 0.1µg, respectively. The amount of DW7 was significantly increased by 4.2-fold compared with the hydrolysate, which suggested that this method is efficient for active peptide screening.

Rice-memolin, a novel peptide derived from rice bran, improves cognitive function after oral administration in mice

Many people eat polished rice, while rice bran, a by-product known to be rich in protein and expected to have potential functions for health benefits, has not been effectively utilized. In this study, we determined that orally administered Val-Tyr-Thr-Pro-Gly (VYTPG) derived from rice bran protein improved cognitive decline in mice fed a high-fat diet (HFD). It was demonstrated that VYTPG was released from model peptides corresponding to fragment sequences of original rice proteins (Os01g0941500, Os01g0872700, and allergenic protein) after treatment with thermolysin, a microorganism-derived enzyme often used in industrial scale processes. The thermolysin digest also improved cognitive decline after oral administration in mice. Because VYTPG (1.0 mg/kg) potently improved cognitive decline and is enzymatically produced from the rice bran, we named it rice-memolin. Next, we investigated the mechanisms underlying the cognitive decline improvement associated with rice-memolin. Methyllycaconitine, an antagonist for α7 nicotinic acetylcholine receptor, suppressed the rice-memolin-induced effect, suggesting that rice-memolin improved cognitive decline coupled to the acetylcholine system. Rice-memolin increased the number of 5-bromo-2'-deoxyuridine (BrdU)-positive cells and promoted the mRNA expression of EGF and FGF-2 in the hippocampus, implying that these neurotropic factors play a role in hippocampal neurogenesis after rice-memolin administration. Epidemiologic studies demonstrated that diabetes is a risk factor for dementia; therefore, we also examined the effect of rice-memolin on glucose metabolism. Rice-memolin improved glucose intolerance. In conclusion, we identified a novel rice-derived peptide that can improve cognitive decline. The mechanisms are associated with acetylcholine and hippocampal neurogenesis. Rice-memolin is the first rice-brain-derived peptide able to improve cognitive decline.

Preparation, Characterization and In Vitro Stability of a Novel ACE-Inhibitory Peptide from Soybean Protein

A soy protein isolate was hydrolyzed with Alcalase®, Flavourzyme® and their combination, and the resulting hydrolysates (A, F and A + F) were ultrafiltered and analyzed through SDS-PAGE. Fractions with MW < 1 kDa were investigated for their ACE-inhibitory activity, and the most active one (A < 1 kDa) was purified by semi-preparative RP-HPLC, affording three further subfractions. NMR analysis and Edman degradation of the most active subfraction (A1) enabled the identification of four putative sequences (ALKPDNR, VVPD, NDRP and NDTP), which were prepared by solid-phase synthesis. The comparison of their ACE-inhibitory activities suggested that the novel peptide NDRP might be the main agent responsible for A1 fraction ACE inhibition (ACE inhibition = 87.75 ± 0.61%; IC50 = 148.28 ± 9.83 μg mL−1). NDRP acts as a non-competitive inhibitor and is stable towards gastrointestinal simulated digestion. The Multiple Reaction Monitoring (MRM) analysis confirmed the presence of NDRP in A < 1 kDa.

Role of Chrononutrition in the Antihypertensive Effects of Natural Bioactive Compounds

Hypertension (HTN) is one of the main cardiovascular risk factors and is considered a major public health problem. Numerous approaches have been developed to lower blood pressure (BP) in hypertensive patients, most of them involving pharmacological treatments. Within this context, natural bioactive compounds have emerged as a promising alternative to drugs in HTN prevention. This work reviews not only the mechanisms of BP regulation by these antihypertensive compounds, but also their efficacy depending on consumption time. Although a plethora of studies has investigated food-derived compounds, such as phenolic compounds or peptides and their impact on BP, only a few addressed the relevance of time consumption. However, it is known that BP and its main regulatory mechanisms show a 24-h oscillation. Moreover, evidence shows that phenolic compounds can interact with clock genes, which regulate the biological rhythm followed by many physiological processes. Therefore, further research might be carried out to completely elucidate the interactions along the time–nutrition–hypertension axis within the framework of chrononutrition.

An updated review of functional properties, debittering methods, and applications of soybean functional peptides

Soybean functional peptides (SFPs) are obtained via the hydrolysis of soybean protein into polypeptides, oligopeptides, and a small amount of amino acids. They have nutritional value and a variety of functional properties, including regulating blood lipids, lowering blood pressure, anti-diabetes, anti-oxidant, preventing COVID-19, etc. SFPs have potential application prospects in food processing, functional food development, clinical medicine, infant milk powder, special medical formulations, among others. However, bitter peptides containing relatively more hydrophobic amino acids can be formed during the production of SFPs, seriously restricting the application of SFPs. High-quality confirmatory human trials are needed to determine effective doses, potential risks, and mechanisms of action, especially as dietary supplements and special medical formulations. Therefore, the physiological activities and potential risks of soybean polypeptides are summarized, and the existing debitterness technologies and their applicability are reviewed. The technical challenges and research areas to be addressed in optimizing debittering process parameters and improving the applicability of SFPs are discussed, including integrating various technologies to obtain higher quality functional peptides, which will facilitate further exploration of physiological mechanism, metabolic pathway, tolerance, bioavailability, and potential hazards of SFPs. This review can help promote the value of SFPs and the development of the soybean industry.

Albumin from Erythrina edulis (Pajuro) as a Promising Source of Multifunctional Peptides

Multifunctional peptides, capable of acting on different body systems through multiple mechanisms of action, offer many advantages over monofunctional peptides, including lower adverse side effects and costs. Erythrina edulis (pajuro) is a legume with a large number of high-quality proteins, of which their potential as a source of antioxidant peptides has been recently reported. In this study, the behavior of these proteins under a sequential enzymatic hydrolysis with digestive and microbial enzymes was investigated by evaluating the multi-functionality of the hydrolyzates. The albumin hydrolyzates obtained after the action of pepsin, pancreatin, and Alcalase showed antioxidant, angiotensin-converting enzyme (ACE), α-amylase, α-glucosidase, and dipeptidyl peptidase (DPP)-IV inhibitory activities. The radical scavenging properties of the hydrolyzate could be responsible for the potent protective effects observed in FeSO4-induced neuroblastoma cells. The findings support the role of pajuro protein as an ingredient of functional foods or nutraceuticals for health promotion and the prevention of oxidative stress, hypertension, and metabolic alteration-associated chronic diseases.