Antihypertensive effect of novel angiotensin I converting enzyme inhibitory peptide from chum salmon (Oncorhynchus keta) skin in spontaneously hypertensive rats

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.

Comparison of Structural and Physicochemical Characteristics of Skin Collagen from Chum Salmon (Cold-Water Fish) and Nile Tilapia (Warm-Water Fish)

This study compared collagens from cold-water and warm-water fish for their structural, rheological, and functional properties, and explored their potential applications, aiming to realize the high-value utilization of marine biological resources. To this end, chum salmon skin collagen (CSSC) and Nile tilapia skin collagen (NTSC) were both successfully extracted. Collagens from the two species had different primary and secondary structures, with NTSC having a higher molecular weight, imino acid content, and α-helices and β-turns content. The denaturation temperatures were 12.01 °C for CSSC and 31.31 °C for NTSC. CSSC was dominated by viscous behavior and its structure varied with temperature, while NTSC was dominated by elastic behavior and its structure remained stable with temperature. Both collagens had good oil holding capacity, foaming capacity, and emulsifying activity, but NTSC had better water holding capacity and foaming and emulsifying stability. Their different properties make CSSC more suitable for the preservation of frozen and chilled foods and the production of sparkling beverages, and give NTSC greater potential in biofunctional materials and solid food processing.

Angiotensin I-Converting Enzyme (ACE) Inhibition and Molecular Docking Study of Meroterpenoids Isolated from Brown Alga, Sargassum macrocarpum

Angiotensin I-converting enzyme (ACE) is an important blood pressure regulator. In this study, we aimed to investigate the ACE-inhibitory effects of meroterpenoids isolated from the brown alga, Sargassum macrocarpum, and the molecular mechanisms underlying ACE inhibition. Four fractions of S. macrocarpum were prepared using hexane, chloroform, ethyl acetate, and water as solvents and analyzed for their potential ACE-inhibitory effects. The chloroform fraction showed the strongest ACE-inhibitory effect, with an IC50 value of 0.18 mg/mL. Three meroterpenoids, sargachromenol, 7-methyl sargachromenol, and sargaquinoic acid, were isolated from the chloroform fraction. Meroterpenoids isolated from S. macrocarpum had IC50 values of 0.44, 0.37, and 0.14 mM. The molecular docking study revealed that the ACE-inhibitory effect of the isolated meroterpenoids was mainly attributed to Zn-ion, hydrogen bonds, pi-anion, and pi-alkyl interactions between the meroterpenoids and ACE. These results suggest that S. macrocarpum could be a potential raw material for manufacturing antihypertensive nutraceutical ingredients.

Improving the Sustainability of Processing By-Products: Extraction and Recent Biological Activities of Collagen Peptides

Society and consumers are increasingly concerned about food safety and the sustainability of food production systems. A significant amount of by-products and discards are generated during the processing of aquatic animals, which still needs to be fully utilized by the food industry. The management and sustainable use of these resources are essential to avoiding environmental pollution and resource waste. These by-products are rich in biologically active proteins, which can be converted into peptides by enzymatic hydrolysis or fermentation treatment. Therefore, exploring the extraction of collagen peptides from these by-products using an enzymatic hydrolysis technology has attracted a wide range of attention from numerous researchers. Collagen peptides have been found to possess multiple biological activities, including antioxidant, anticancer, antitumor, hypotensive, hypoglycemic, and anti-inflammatory properties. These properties can enhance the physiological functions of organisms and make collagen peptides useful as ingredients in food, pharmaceuticals, or cosmetics. This paper reviews the general methods for extracting collagen peptides from various processing by-products of aquatic animals, including fish skin, scales, bones, and offal. It also summarizes the functional activities of collagen peptides as well as their applications.

Structure Characterization and Antihypertensive Effect of an Antioxidant Peptide Purified from Alcalase Hydrolysate of Velvet Antler

Recently, interest in food-derived bioactive peptides as promising ingredients for the prevention and improvement of hypertension is increasing. The purpose of this study was to determine the structure and antihypertensive effect of an antioxidant peptide purified from velvet antler in a previous study and evaluate its potential as a various bioactive peptide. Molecular weight (MW) and amino acid sequences of the purified peptide were determined by quadrupole time-of-flight electrospray ionization mass spectroscopy. The angiotensin I-converting enzyme (ACE) inhibition activity of the purified peptide was assessed by enzyme reaction methods and in silico molecular docking analysis to determine the interaction between the purified peptide and ACE. Also, antihypertensive effect of the purified peptide in spontaneously hypertensive rats (SHRs) was investigated. The purified antioxidant peptide was identified to be a pentapeptide Asp-Asn-Arg-Tyr-Tyr with a MW of 730.31 Da. This pentapeptide showed potent inhibition activity against ACE (IC₅₀ value, 3.72 μM). Molecular docking studies revealed a good and stable binding affinity between purified peptide and ACE and indicated that the purified peptide could interact with HOH2570, ARG522, ARG124, GLU143, HIS387, TRP357, and GLU403 residues of ACE. Furthermore, oral administration of the pentapeptide significantly reduced blood pressure in SHRs. The pentapeptide derived from enzymatic hydrolysate of velvet antler is an excellent ACE inhibitor. It might be effectively applied as an animal-based functional food ingredient.

Novel Peptide Sequences with ACE-Inhibitory and Antioxidant Activities Derived from the Heads and Bones of Hybrid Groupers (Epinephelus lanceolatus × Epinephelus fuscoguttatus)

The heads and bones of hybrid groupers are potential precursors for angiotensin-converting enzyme (ACE)-inhibitory and antioxidant peptides. The aim of this study was to isolate the dual-action peptides from the Alcalase-treated head and bone hydrolysate of hybrid groupers followed by identification of the novel peptides. The stability of these peptides against stimulated in vitro gastrointestinal digestion (SGID) was also determined. Fraction HB-IV (less than 1 kDa) obtained from ultrafiltration showed the strongest ACE-inhibition ability (IC50: 0.28 mg/mL), which was comparable to the potency of the commercial supplement, PeptACE (IC50: 0.22 mg/mL). This fraction also demonstrated the highest hydroxyl radical scavenging and metal-chelating activities. However, further fractionation of HB-IV by a series of chromatography resulted in peptide fractions of reduced ACE-inhibitory and antioxidant activities. The hydroxyl radical scavenging and reduction potential of HB-IV were enhanced, whereas ACE-inhibitory and metal-chelating activities were reduced following SGID. A total of 145 peptide sequences were identified from HB-IV, of which 137 peptides were novel to the BIOPEP database. The results suggested that the bioactive peptides isolated from the heads and bones of hybrid groupers could be used as functional foods/ingredients with potential ACE-inhibitory and antioxidant effects.

A peptide fraction from hardened common beans (Phaseolus vulgaris) induces endothelium-dependent antihypertensive and renal effects in rats

Beans reached the research spotlight as a source of bioactive compounds capable of modulating different functions. Recently, we reported antioxidant and oxidonitrergic effect of a low molecular weight peptide fraction (<3 kDa) from hardened bean (Phaseolus vulgaris) in vitro and ex vivo, which necessitate further in vivo assessments. This work aimed to evaluate the hypotensive effect and the involved physiological mechanisms of the hardened common bean peptide (Phaseolus vulgaris) in normotensive (Wistar) and hypertensive (SHR) animals. Bean flour was combined with a solution containing acetonitrile, water and formic acid (25: 24: 1). Protein extract (PV3) was fractioned (3 kDa membrane). We assessed PV3 effects on renal function and hemodynamics of wistar (WT-normotensive) and spontaneously hypertensive rats (SHR) and measured systemic arterial pressure and flow in aortic and renal beds. The potential endothelial and oxidonitrergic involvements were tested in isolated renal artery rings. As results, we found that PV3: I) decreased food consumption in SHR, increased water intake and urinary volume in WT, increased glomerular filtration rate in WT and SHR, caused natriuresis in SHR; II) caused NO- and endothelium-dependent vasorelaxation in renal artery rings; III) reduced arterial pressure and resistance in aortic and renal vascular beds; IV) caused antihypertensive effects in a dose-dependent manner. Current findings support PV3 as a source of bioactive peptides and raise the potential of composing nutraceutical formulations to treat renal and cardiovascular diseases.

Bovine Bone Gelatin-Derived Peptides: Food Processing Characteristics and Evaluation of Antihypertensive and Antihyperlipidemic Activities

This study aimed to evaluate the food processing properties of bovine bone gelatin-derived peptides (BGPs) and their effects and mechanisms on hypertension and hypertension complications in spontaneously hypertensive rats (SHRs). BGPs had good acid, high temperature, and NaCl resistance abilities in vitro. Additionally, Maillard reaction of BGPs with low-dose reducing sugar (≤15%) exhibited a free radical scavenging effect. BGPs significantly reduced the blood pressure, triglyceride levels, and the low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio in SHRs through downregulated angiotensin converting enzyme (ACE), angiotensin II (Ang II), and Ang II type 1 receptor (AT1R) levels and the upregulated Ang II type 2 receptor (AT2R) level. In brief, BGP could alleviate hypertension and dyslipidemia in SHRs by inhibiting ACE/Ang II/AT1R and activating the Ang II/AT2R signaling pathway. Our study suggests that BGP has good food processing properties and could be a potential nutraceutical for antihypertensive and antihyperlipidemic issues.

Improvement on blood pressure and skin using roselle drink: A clinical trial

Roselle (Hibiscus sabdariffa L.) is an increasingly attractive plant for its health and pharmaceutical, beverage, and cosmetic applications. The purpose of this study was to investigate the clinical effects of roselle drink on antioxidant activity, blood pressure, and skin condition. Roselle drink used in this study contained rich phenolics (1.96 g of gallic acid equivalent/100 ml) and anthocyanins (1.65 g of cyanidin-3-glucoside equivalent/100 ml). In a randomized, cross-over, double-blind, placebo-controlled clinical study, 39 healthy adults received drank 200 ml of roselle drink or placebo-control drink for 6 months. A significant reduction in the blood pressure was observed in the roselle drink treated group when compared with preintervention values. After 6 months of treatment with roselle drink, serum phenolics contents, the levels of Trolox equivalent antioxidant capacity (TEAC), glutathione, superoxide dismutase (SOD), glucose-6-phosphate dehydrogenase (G-6-PDH), glutathione peroxidase (GSH-Px), and glutathione reductase (GSH-Rd) were significantly increased in healthy subjects. However, a significant increment in skin redness and skin moisture was observed in the facial skin of roselle drink-treated participants. Oral administration of roselle drink for 6 months significantly lowered the blood pressure, improved antioxidation level, and positively regulated skin redness as well as moisture. Phenolics and anthocyanins in roselle could be the major potential contributors to such health effects. PRACTICAL APPLICATIONS: Roselle is a typical plant. Continuous administration of roselle drink clearly improved antioxidation levels, reduced blood pressure and positively regulated skin redness and moisture. Phenloics and anthocyanins in roselle could be the major potentila contributors of such health benefits.

Shrimp peptide hydrolysate modulates the immune response in cyclophosphamide immunosuppressed mice model

Bioactive peptides are naturally found in various foods and were shown to have various distinct physiological as well as medicinal benefits. In this study shrimp peptide hydrolysate (SPH) was prepared to investigate its immunomodulatory effect against cyclophosphamide (CTX) induced immunosuppressed mice. The SPH effect was also analyzed on murine macrophage (RAW264.7 cells). The findings show that SPH stimulates macrophages to form multiple pseudopodia, has no cytotoxic effect, and increases phagocytic activity in RAW264.7 cells. Furthermore, the immunosuppressed in-vivo model illustrates the improvement in various aspects, that is body weight, escalation in immune organ index, and ameliorates histopathological transformation of thymus along with the spleen. SPH enhances cell-mediated immunity by facilitating splenocyte proliferation and inhibit excessive apoptosis. Moreover, the significant outcome had been observed with the upregulation of cytokines interferon-gamma (IFN-ϒ), interleukin-2 (IL-2) level and simultaneously downregulate certain genes include interleukin-4 (IL-4) and interleukin-10 (IL-10). Additionally, SPH expedites cellular immunity by enhancing the regulation of immunoglobulin A (IgA) and immunoglobulin M (IgM). However, these findings support the hypothesis that SPH is an effective immunomodulatory agent capable of preventing immune system hypofunction. It is necessary to investigate the detailed mechanism to rule out any unforeseen effects of SPH in future research. PRACTICAL APPLICATIONS: Chemotherapy medications, despite their dominating detrimental effects of damaging immunological organs such as the spleen and thymus, extend the treatment process as well as the destruction of the self-immune system. This study found that SPH is an effective immunomodulatory agent capable of avoiding immune organ hypofunction and improving cell mediate immunity by enhancing macrophage activation, phagocytosis, spleenocyte proliferation, suppressing apoptosis, and elevating cytokines and antibodies. As a result, SPH can be utilized as a nutritional and functional dietary supplement to boost immunological modulation in combination with chemotherapy medications in order to lessen their adverse effects.

Utility of a Hydrolysate from Overproduced Paralichthys olivaceus for Hypertension Treatment: Correlation between Physical Properties and Potent Anti-Hypertensive Activities

Aquacultured fish are the richest natural source of protein. However, their overproduced biomass is often discarded due to production imbalance, causing considerable losses to the fishery industry. Therefore, it is necessary to utilize surplus fish and add value to overproduced fish. We performed complex enzyme-assisted hydrolysis to determine the correlation between its physical characteristics and anti-hypertensive activity in vitro and in vivo using an SHR model. Protamex-Pepsin assisted hydrolysate from Paralichthys olivaceus (PO_ppH) produced by complex enzyme-assisted hydrolysis contained low-molecular-weight peptides and amino acids with anti-hypertensive activity. PO_ppH regulated blood pressure and serum angiotensin II and angiotensin-I-converting enzyme levels, and histological and ultrasound image analysis revealed substantially reduced thickness and diameter of the carotid aorta in the PO_ppH-administered SHR group. Therefore, we propose to reduce food loss due to overproduction by utilizing the anti-hypertensive activity and physical properties of PO_ppH; the results demonstrate its application as a therapeutic agent.

Seafood Discards: A Potent Source of Enzymes and Biomacromolecules With Nutritional and Nutraceutical Significance

In recent times, the seafood industry is found to produce large volumes of waste products comprising shrimp shells, fish bones, fins, skins, intestines, and carcasses, along with the voluminous quantity of wastewater effluents. These seafood industry effluents contain large quantities of lipids, amino acids, proteins, polyunsaturated fatty acids, minerals, and carotenoids mixed with the garbage. This debris not only causes a huge wastage of various nutrients but also roots in severe environmental contamination. Hence, the problem of such seafood industry run-offs needs to be immediately managed with a commercial outlook. Microbiological treatment may lead to the valorization of seafood wastes, the trove of several useful compounds into value-added materials like enzymes, such as lipase, protease, chitinase, hyaluronidase, phosphatase, etc., and organic compounds like bioactive peptides, collagen, gelatin, chitosan, and mineral-based nutraceuticals. Such bioconversion in combination with a bio-refinery strategy possesses the potential for environment-friendly and inexpensive management of discards generated from seafood, which can sustainably maintain the production of seafood. The compounds that are being produced may act as nutritional sources or as nutraceuticals, foods with medicinal value. Determining utilization of seafood discard not only reduces the obnoxious deposition of waste but adds economy in the production of food with nutritional and medicinal importance, and, thereby meets up the long-lasting global demand of making nutrients and nutraceuticals available at a nominal cost.

Effects of Shrimp Peptide Hydrolysate on Intestinal Microbiota Restoration and Immune Modulation in Cyclophosphamide-Treated Mice

The gut microbiota is important in regulating host metabolism, maintaining physiology, and protecting immune homeostasis. Gut microbiota dysbiosis affects the development of the gut microenvironment, as well as the onset of various external systemic diseases and metabolic syndromes. Cyclophosphamide (CTX) is a commonly used chemotherapeutic drug that suppresses the host immune system, intestinal mucosa inflammation, and dysbiosis of the intestinal flora. Immunomodulators are necessary to enhance the immune system and prevent homeostasis disbalance and cytotoxicity caused by CTX. In this study, shrimp peptide hydrolysate (SPH) was evaluated for immunomodulation, intestinal integration, and microbiota in CTX-induced immunosuppressed mice. It was observed that SPH would significantly restore goblet cells and intestinal mucosa integrity, modulate the immune system, and increase relative expression of mRNA and tight-junction associated proteins (Occludin, Zo-1, Claudin-1, and Mucin-2). It also improved gut flora and restored the intestinal microbiota ecological balance by removing harmful microbes of various taxonomic groups. This would also increase the immune organs index, serum levels of cytokines (IFN-ϒ, IL1β, TNF-α, IL-6), and immunoglobin levels (IgA, IgM). The Firmicutes/Bacteroidetes proportion was decreased in CTX-induced mice. Finally, SPH would be recommended as a functional food source with a modulatory effect not only on intestinal microbiota, but also as a potential health-promoting immune function regulator.

A critical review on the health benefits of fish consumption and its bioactive constituents

As one of food sources, fish provides sufficient nutrition to human. Diverse nutrients in fish make fish an important nutrient source available easily across the globe. Fish is proven to possess several health benefits, such as anti-oxidation, anti-inflammation, wound healing, neuroprotection, cardioprotection, and hepatoprotection properties. Fish proteins, such as immunoglobins, act as defense agents against viral and bacterial infections and prevent protein-calorie malnutrition. Besides, fish oil constituents, such as polyunsaturated fatty acids (PUFAs), regulate various signaling pathways, such as nuclear factor kappa B pathway, Toll-like receptor pathway, transforming growth factor-β (TGF-β) pathway, and peroxisome proliferators activated receptor (PPAR) pathways. In this review, the literature about health benefits of fish consumption are accumulated from PubMed, Google Scholar, Scopus, and the mechanistic action of health benefits are summarized. Fish consumption at least twice per week as part of a healthy diet is beneficial for a healthy heart. More advances in this field could pose fish as a major nutrients source of foods.

Antihypertensive activity of orally consumed ACE-I inhibitory peptides

Food proteins are sources for ACE-I inhibitory peptides that can be extracted by enzymatic hydrolysis exhibiting anti-hypertensive activity. However, these peptides are prone to further degradation by gastrointestinal enzymes during oral consumption. Bio-activity of these peptides is dependent on the resultant peptide post gastrointestinal digestion. To exhibit the bio-activity, they need to be absorbed in intact form. Although studies suggest di and tri-peptides show better ACE-I inhibitory activity, few peptides show altered IC₅₀ values under simulated gastrointestinal digestion. Moreover, ACE-I inhibitory peptides with low IC₅₀ values have not shown effective anti-hypertensive activity in spontaneously hypertensive rats when administered orally. Few ACE-I inhibitory peptides have reported effective reduction in systolic blood-pressure when administered through intravenously. During oral consumption of such peptides, the actual peptide sequence responsible for reducing blood-pressure is a result of breakdown in gastrointestinal tract. The fate of targeted peptides during digestion depends on amino acid sequence of the protein containing the specific site for cleavage where the action of digestive enzymes takes place. Therefore, this review attempts to explain the factors that affect the anti-hypertensive activity of ACE-I inhibitory peptides during oral consumption. It also highlights subsequent absorption of ACE-I inhibitory peptides after gastrointestinal digestion.

Novel Angiotensin-Converting Enzyme Inhibitory Peptides Identified from Walnut Glutelin-1 Hydrolysates: Molecular Interaction, Stability, and Antihypertensive Effects

In recent years, angiotensin-converting enzyme (ACE) inhibitory peptide has become a research hotspot because of its essential role in maintaining human blood pressure balance. In this study, two novel ACE inhibitory peptides of Val-Glu-Arg-Gly-Arg-Arg-lle-Thr-Ser-Val (Valine-Glutamate-Arginine-Glycine-Arginine-Arginine-Isoleucine-Threonine-Serine-Valine, VERGRRITSV) and Phe-Val-Ile-Glu-Pro-Asn-Ile-Thr-Pro-Ala (Phenylalanine-Valine-Isoleucine-Glutamate-Proline-Asparagine-Isoleucine-Threonine-Proline-Alanine, FVIEPNITPA) were isolated and purified from defatted walnut meal hydrolysates through a series of preparation processes including ultrafiltration, Sephadex G-15 gel chromatography, and reverse high performance liquid chromatography (RP-HPLC). Both peptides showed high ACE inhibitory activities. The molecular docking study revealed that VERGRRITSV and FVIEPNITPA were primarily attributed to the formation of strong hydrogen bonds with the active pockets of ACE. The binding free energies of VERGRRITSV and FVIEPNITPA with ACE were -14.99 and -14.69 kcal/mol, respectively. Moreover, these ACE inhibitory peptides showed good stability against gastrointestinal enzymes digestion and common food processing conditions (e.g., temperature and pH, sugar, and salt treatments). Furthermore, animal experiment results indicated that the administration of VERGRRITSV or FVIEPNITPA exhibited antihypertensive effects in spontaneously hypertensive rats. Our results demonstrated that walnut could be a potential source of bioactive peptides with ACE inhibitory activity.

Purification, characterization and molecular docking study of angiotensin-I converting enzyme (ACE) inhibitory peptide from shortfin scad (Decapterus macrosoma) protein hydrolysate

Hypertension is a threatening chronic disease, which become a global killer among the adult population. The mortality rate increasing day by day even several Angiotensin I-converting enzyme (ACE) inhibitor drugs were introduced. Bioactive peptides derived from aquatic resources exhibits potential ACE inhibitory activity. The objective of this work is to report the purification and molecular docking studies of angiotensin-I converting enzyme (ACE) inhibitory peptide isolated from shortfin scad (Decapterus macrosoma) waste protein hydrolysate (SWH), enzymatically prepared by using alcalase. The purification process included ultrafiltration, gel filtration and reverse phase high performance liquid chromatography (RP-HPLC). Results showed that ultra-filtered peptide fraction (< 3 kDa) possessed the highest ACE inhibitory activity, followed by the fraction 14 by gel filtration. Fraction P obtained by RP-HPLC, with the amino acid sequence of RGVGPVPAA (IC₅₀ = 0.20 mg/ml) was identified. In terms of ACE inhibition, the Lineweaver-Burk plot showed that the SWH peptide obtained acted as a competitive ACE inhibitor. The molecular docking studies showed that the SWH peptide exhibit hydrogen bonds and Pi-interactions with ACE by Z-dock scores. These results showed that the purified peptide isolated from shortfin scad waste hydrolysate has potential antihypertensive properties which could potentially be used as functional food ingredients.

Exploiting of Secondary Raw Materials from Fish Processing Industry as a Source of Bioactive Peptide-Rich Protein Hydrolysates

Developing peptide-based drugs are very promising to address many of the lifestyle mediated diseases which are prevalent in a major portion of the global population. As an alternative to synthetic peptide-based drugs, derived peptides from natural sources have gained a greater attention in the last two decades. Aquatic organisms including plants, fish and shellfish are known as a rich reservoir of parent protein molecules which can offer novel sequences of amino acids in peptides, having unique bio-functional properties upon hydrolyzing with proteases from different sources. However, rather than exploiting fish and shellfish stocks which are already under pressure due to overexploitation, the processing discards, regarded as secondary raw material, could be a potential choice for peptide based therapeutic development strategies. In this connection, we have attempted to review the scientific reports in this area of research that deal with some of the well-established bioactive properties, such as antihypertensive, anti-oxidative, anti-coagulative, antibacterial and anticarcinogenic properties, with reference to the type of enzymes, substrate used, degree of particular bio-functionality, mechanism, and wherever possible, the active amino acid sequences in peptides. Many of the studies have been conducted on hydrolysate (crude mixture of peptides) enriched with low molecular bioactive peptides. In vitro and in vivo experiments on the potency of bioactive peptides to modulate the human physiological functions beneficially have demonstrated that these peptides can be used in the prevention and treatment of non-communicable lifestyle mediated diseases. The information synthesized under this review could serve as a point of reference to drive further research on and development of functionally active therapeutic natural peptides. Availability of such scientific information is expected to open up new zones of investigation for adding value to underutilized secondary raw materials, which in turn paves the way for sustainability in fish processing. However, there are significant challenges ahead in exploring the fish waste as a source of bioactive peptides, as it demands more studies on mechanisms and structure–function relationship understanding as well as clearance from regulatory and statutory bodies before reaching the end user in the form of supplement or therapeutics.

Properties of peptides released from salmon and carp via simulated human-like gastrointestinal digestion described applying quantitative parameters

Apart from the classical (experimental) methods, biologically active peptides can be studied via bioinformatics approach, also known as in silico analysis. This study aimed to verify the following research hypothesis: ACE inhibitors and antioxidant peptides can be released from salmon and carp proteins during simulated in silico human-like gastrointestinal digestion. The potential to release biopeptides was evaluated using the BIOPEP-UWM quantitative criteria including the profile of biological activity, frequency of the occurrence (A)/release (AE) of fragments with an ACE inhibitory or antioxidant activity by selected enzymes, and relative frequency of release of bioactive fragments with a given activity by selected enzymes (W). Salmon collagen and myofibrillar proteins of carp turned out to be the best potential source of the searched peptides-ACE inhibitors and antioxidant peptides. Nonetheless, after digestion, the highest numbers of ACE inhibitors and antioxidant peptides were potentially released from the myofibrillar proteins of salmon and carp. Peptide Ranker Score, Pepsite2, and ADMETlab platform were applied to evaluate peptides' bioactivity potential, their safety and drug-like properties. Among the 63 sequences obtained after the simulated digestion of salmon and carp proteins, 30 were considered potential biopeptides. The amino acid sequences of ACE-inhibiting and antioxidant peptides were predominated by P, G, F, W, R, and L. The predicted high probability of absorption of most analyzed peptides and their low toxicity should be considered as their advantage.

Bioactive Compounds of Nutraceutical Value from Fishery and Aquaculture Discards

Seafood by-products, produced by a range of different organisms, such as fishes, shellfishes, squids, and bivalves, are usually discarded as wastes, despite their possible use for innovative formulations of functional foods. Considering that “wastes” of industrial processing represent up to 75% of the whole organisms, the loss of profit may be coupled with the loss of ecological sustainability, due to the scarce recycling of natural resources. Fish head, viscera, skin, bones, scales, as well as exoskeletons, pens, ink, and clam shells can be considered as useful wastes, in various weight percentages, according to the considered species and taxa. Besides several protein sources, still underexploited, the most interesting applications of fisheries and aquaculture by-products are foreseen in the biotechnological field. In fact, by-products obtained from marine sources may supply bioactive molecules, such as collagen, peptides, polyunsaturated fatty acids, antioxidant compounds, and chitin, as well as catalysts in biodiesel synthesis. In addition, those sources can be processed via chemical procedures, enzymatic and fermentation technologies, and chemical modifications, to obtain compounds with antioxidant, anti-microbial, anti-cancer, anti-hypertensive, anti-diabetic, and anti-coagulant effects. Here, we review the main discards from fishery and aquaculture practices and analyse several bioactive compounds isolated from seafood by-products. In particular, we focus on the possible valorisation of seafood and their by-products, which represent a source of biomolecules, useful for the sustainable production of high-value nutraceutical compounds in our circular economy era.

Roles of Dietary Bioactive Peptides in Redox Balance and Metabolic Disorders

Bioactive peptides (BPs) are fragments of 2-15 amino acid residues with biological properties. Dietary BPs derived from milk, egg, fish, soybean, corn, rice, quinoa, wheat, oat, potato, common bean, spirulina, and mussel are reported to possess beneficial effects on redox balance and metabolic disorders (obesity, diabetes, hypertension, and inflammatory bowel diseases (IBD)). Peptide length, sequence, and composition significantly affected the bioactive properties of dietary BPs. Numerous studies have demonstrated that various dietary protein-derived BPs exhibited biological activities through the modulation of various molecular mechanisms and signaling pathways, including Kelch-like ECH-associated protein 1/nuclear factor erythroid 2-related factor 2/antioxidant response element in oxidative stress; peroxisome proliferator-activated-γ, CCAAT/enhancer-binding protein-α, and sterol regulatory element binding protein 1 in obesity; insulin receptor substrate-1/phosphatidylinositol 3-kinase/protein kinase B and AMP-activated protein kinase in diabetes; angiotensin-converting enzyme inhibition in hypertension; and mitogen-activated protein kinase and nuclear factor-kappa B in IBD. This review focuses on the action of molecular mechanisms of dietary BPs and provides novel insights in the maintenance of redox balance and metabolic diseases of human.

Animal by-products collagen and derived peptide, as important components of innovative sustainable food systems-a comprehensive review

In 2020, the world's food crisis and health industry ushered into a real outbreak. On one side, there were natural disasters such as the novel coronavirus (2019-nCoV), desert locusts, floods, and droughts exacerbating the world food crisis, while on the other side, the social development and changes in lifestyles prompted the health industry to gradually shift from a traditional medical model to a new pattern of prevention, treatment, and nourishment. Therefore, this article reviews animal by-products collagen and derived peptide, as important components of innovative sustainable food systems. The review also considered the preparation, identification, and characterization of animal by-product collagen and collagen peptides as well as their impacts on the food system (including food processing, packaging, preservation, and functional foods). Finally, the application and research progress of animal by-product collagen and peptide in the food system along with the future development trend were discussed. This knowledge would be of great significance for a comprehensive understanding of animal by-product collagen and collagen peptides and would encourage the use of collagen in food processing, preservation, and functional foods.

Novel Umami Peptide IPIPATKT with Dual Dipeptidyl Peptidase-IV and Angiotensin I-Converting Enzyme Inhibitory Activities

A novel umami peptide, IPIPATKT, showed excellent dual dipeptidyl peptidase-IV (DPP-IV) and angiotensin I-converting enzyme (ACE) inhibitory activities, the IC₅₀ values were 64 and 265 μM, respectively. Molecular docking displayed that IPIPATKT was docked into the S1 and S2 pockets of ACE, and it was close to the active site pocket of DPP-IV. The insulin-resistant-HepG2 (IR-HepG2) cell model and human umbilical vein endothelial cell (HUVEC) model showed that the peptide significantly increased the content of glucose, the activities of hexokinase, pyruvate kinase, and the concentration of nitric oxide (p < 0.01), while it reduced the content of endothelin-1 (ET-1). IPIPATKT exhibited a hypotensive effect (-23.5 ± 2.2 mmHg) and attenuated the increase in glucose levels in vivo, as demonstrated using spontaneous hypertensive rats (SHRs) and C57BL/6N mice. We reported the in vivo activities of the umami peptide with dual hypertensive and hypoglycemic effects for the first time.

Fish Waste: From Problem to Valuable Resource

Following the growth of the global population and the subsequent rapid increase in urbanization and industrialization, the fisheries and aquaculture production has seen a massive increase driven mainly by the development of fishing technologies. Accordingly, a remarkable increase in the amount of fish waste has been produced around the world; it has been estimated that about two-thirds of the total amount of fish is discarded as waste, creating huge economic and environmental concerns. For this reason, the disposal and recycling of these wastes has become a key issue to be resolved. With the growing attention of the circular economy, the exploitation of underused or discarded marine material can represent a sustainable strategy for the realization of a circular bioeconomy, with the production of materials with high added value. In this study, we underline the enormous role that fish waste can have in the socio-economic sector. This review presents the different compounds with high commercial value obtained by fish byproducts, including collagen, enzymes, and bioactive peptides, and lists their possible applications in different fields.

Tilapia viscera hydrolysate extract alleviates oxidative stress and renal damage in deoxycorticosterone acetate-salt-induced hypertension rats

Background and Aim:

Hypertension is closely related to oxidative stress conditions, which increases malondialdehyde (MDA) expression and renal damage. Tilapia viscera hydrolysate extract (TVHE) contains compounds and peptides that act as antioxidants. This study aimed to investigate TVHE therapy effect on MDA levels and renal histological conditions in deoxycorticosterone acetate (DOCA)-salt-induced hypertension rats.

Materials and Methods:

Tilapia viscera were defatted and hydrolyzed using Alcalase enzyme to obtain TVHE. TVHE antioxidant activity was measured using the 1,1-diphenyl-2-picrylhydrazyl method. Fifteen Wistar male rats were divided into five groups: Normal control (without induced DOCA-salt), DOCA-salt, DOCA-salt+Captopril 5 mg/kg body weight (BW), DOCA-salt+TVHE 150 mg/kg BW, and DOCA-salt+TVHE 300 mg/kg BW. MDA level and renal histology were observed in each group.

Results:

TVHE half maximal inhibitory concentration values ranged from 3.87±0.35 μg/mL to 42.03±3.55 μg/mL, which were identified as in the very strong Blois category. TVHE and captopril therapy reduced MDA expression significantly (p<0.05) compared to DOCA-salt only. TVHE and captopril therapy also improved glomerular damage in DOCA-salt-induced hypertension rats.

Conclusion:

TVHE has antioxidant ability, decreased MDA level, and decreased glomerular damage in DOCA-salt-induced hypertension rats.

Cardiovascular Active Peptides of Marine Origin with ACE Inhibitory Activities: Potential Role as Anti-Hypertensive Drugs and in Prevention of SARS-CoV-2 Infection

Growing interest in hypertension-one of the main factors characterizing the cardiometabolic syndrome (CMS)-and anti-hypertensive drugs raised from the emergence of a new coronavirus, SARS-CoV-2, responsible for the COVID19 pandemic. The virus SARS-CoV-2 employs the Angiotensin-converting enzyme 2 (ACE2), a component of the RAAS (Renin-Angiotensin-Aldosterone System) system, as a receptor for entry into the cells. Several classes of synthetic drugs are available for hypertension, rarely associated with severe or mild adverse effects. New natural compounds, such as peptides, might be useful to treat some hypertensive patients. The main feature of ACE inhibitory peptides is the location of the hydrophobic residue, usually Proline, at the C-terminus. Some already known bioactive peptides derived from marine resources have potential ACE inhibitory activity and can be considered therapeutic agents to treat hypertension. Peptides isolated from marine vertebrates, invertebrates, seaweeds, or sea microorganisms displayed important biological activities to treat hypertensive patients. Here, we reviewed the anti-hypertensive activities of bioactive molecules isolated/extracted from marine organisms and discussed the associated molecular mechanisms involved. We also examined ACE2 modulation in sight of SARS2-Cov infection prevention.

Structural Evidence for Antihypertensive Effect of an Antioxidant Peptide Purified from the Edible Marine Animal Styela clava

This study investigated the antihypertensive effects of an antioxidant peptide, Leu-Trp-His-Thr-His (LWHTH), purified from Styela clava peptic hydrolysate, to assess the bioactivity of the peptide and verify the value of S. clava as a health-promoting food. Also, the study presented structural evidence for the effects of LWHTH. The inhibitory effect of LWHTH on angiotensin I-converting enzyme (ACE) was assessed using enzyme reaction methods and the simulation methods in computational space. LWHTH inhibited ACE with an IC₅₀ value of 16.42 ± 0.45 μM. The LWHTH structure was stable, and its ACE inhibitory effect was retained under simulated gastrointestinal conditions. In silico simulations revealed that LWHTH binds the active site of ACE, with residues LW making the ACE-LWHTH complex stable and residues HTH making the complex strong. Furthermore, LWHTH significantly reduced blood pressure in spontaneously hypertensive rats. These results demonstrate that LWHTH has the potential to be a healthy functional food with antihypertensive effects. Therefore, S. clava consumption may be beneficial for human health.

Bioactive peptides attenuate cardiac apoptosis in spontaneously hypertensive rat hearts through activation of autophagy and mitochondrial biogenesis pathway

Alcalase potato protein hydrolysate (APPH) might have a very important role in therapeutic effects. This study aims to examine the beneficial effects of bioactive peptides (DIKTNKPVIF [DI] and IF) from APPH supplement in the regulation of cardiac apoptosis, autophagy, and mitochondrial biogenesis pathway in spontaneously hypertensive rats (SHR). We have investigated ejection fraction, fractional shortening, Tunel assay, apoptosis, autophagy, and mitochondrial biogenesis pathway marker expression to show the efficacy of bioactive peptides in an SHR model. Bioactive peptides significantly upregulate ejection fraction and fractional shortening in SHR rats. SHR rats exhibited higher protein expression of apoptotic markers such as BAD, cytochrome c, and caspase 3. Finally, the bioactive peptides upregulate survival proteins (p-AKT/p-PI3K), autophagy (Beclin1/LC3B), and mitochondrial biogenesis (p-AMPKα/SIRT1/PGC1α/p-Foxo3a/Nrf2/CREB) marker expressions compared with the SHR groups. In summary, the bioactive peptides protect the heart tissues through the activation of autophagy and mitochondrial biogenesis pathway and thereby attenuate cardiac apoptosis in a spontaneously hypertensive rat model.

Comparison of an angiotensin-I-converting enzyme inhibitory peptide from tilapia (Oreochromis niloticus) with captopril: inhibition kinetics, in vivo effect, simulated gastrointestinal digestion and a molecular docking study

BACKGROUND

In order to utilize tilapia skin gelatin hydrolysate protein, which is normally discarded as industrial waste in the process of fish manufacture, we study the in vivo and in vitro angiotensin-I-converting enzyme (ACE) inhibitory activity of the peptide Leu-Ser-Gly-Tyr-Gly-Pro (LSGYGP). The aim was to provide a pharmacological basis of the development of minimal side effects of ACE inhibitors by comparative analysis with captopril in molecular docking.

RESULTS

This peptide from protein-rich wastes showed excellent ACE inhibitory activity (IC₅₀  = 2.577 μmol L^-1 ) and exhibited a mixed noncompetitive inhibitory pattern with Lineweaver-Burk plots. Furthermore, LSGYGP and captopril groups both showed significant decreases in blood pressure after 6 h and maintained good digestive stability over 4 h. Molecular bond interactions differentiate competitive captopril upon hydrogen bond interactions and Zn(II) interaction. The C-terminal Pro generates three interactions (hydrogen bonds, hydrophilic interactions and Van der Waals interactions) in the peptide and effectively interacts with the S1 and S2 pockets of ACE.

CONCLUSION

LSGYGP, with an IC₅₀ value of 2.577 μmol L^-1 , has an antihypertensive effect in spontaneously hypertensive rats. Through comparison with captopril, this study revealed that LSGYGP may be a potential food-derived ACE inhibitory peptide and could act as a functional food ingredient to prevent hypertension. © 2019 Society of Chemical Industry.

Preparation and Identification of Novel Antihypertensive Peptides from the In Vitro Gastrointestinal Digestion of Marine Cobia Skin Hydrolysates

This research focuses on cobia skin hydrolysates and their antihypertensive effects via the inhibitory activities of angiotensin I-converting enzyme (ACE). Marine fish Cobia (Rachycentron canadum) skin was hydrolysed for 5 h using Protamex and Protease N to obtain the cobia skin protein hydrolysates PX-5 and PN-5, respectively. The soluble protein and peptide contents of the PX-5 were 612 and 270 mg/g, respectively, and for the PN-5, 531 and 400 mg/g, respectively. The IC₅₀ of PX-5 and PN-5 on ACE was 0.221 and 0.291 mg/mL, respectively. Increasing the IC₅₀ from 0.221 to 0.044 mg/mL by simulated gastrointestinal digestion (PX-5G) reduced the ACE-inhibitory capacity of PX-5. Using gel filtration chromatography, the PX-5G was fractioned into eight fractions. The molecular weight of the fifth fraction from PX-5G was between 630 and 450 Da, and the highest inhibitory efficiency ratio on ACE was 1552.4%/mg/mL. We identified four peptide sequences: Trp-Ala-Ala, Ala-Trp-Trp, Ile-Trp-Trp, and Trp-Leu, with IC₅₀ values for ACE of 118.50, 9.40, 0.51, and 26.80 μM, respectively. At a dose of 600 mg PX-5 powder/kg body weight, in spontaneously hypertensive rats PX-5's antihypertensive effect significantly reduced systolic and diastolic blood pressure by 21.9 and 15.5 mm Hg, respectively, after 4 h of oral gavage.

Antidiabetic Effects of a Short Peptide of Potato Protein Hydrolysate in STZ-Induced Diabetic Mice

Alcalase- generated potato protein hydrolysate (APPH) is a potential bioactive peptide against diabetes mellitus (DM) and DM-associated secondary effects in animal models. The aim of the present study was to find the efficiency of a deca-peptide DIKTNKPVIF (DF) from APPH against DM. Six-week-old male ICR mice were divided into the following groups: Control, Control+DF (received 50 mg/kg DF), streptozotocin (STZ)-induced DM group, DM+Acarbose group (20 mg/kg of acarbose), DM+DF-L (25 mg/kg of DF), DM+DF-H (50 mg/kg of DF), and DM+APPH (50 mg/kg of APPH). Comparable to APPH, treatment with DF effectively regulated blood glucose level and also controlled plasma total glycerol (TG), total cholesterol (TC), insulin, and HbA1c levels in DM animals. DF treatment also showed evidence of ameliorating DM-associated damages in the pancreatic islets and in the liver, heart, and kidney tissues. Therefore, the results demonstrate that the short synthetic peptide-DF may effectively provide protection against DM-associated damages.

Preparation and Identification of ACE Inhibitory Peptides from the Marine Macroalga Ulva intestinalis

Angiotensin I-converting enzyme (ACE) inhibitory peptides derived from seaweed represent a potential source of new antihypertensive. The aim of this study was to isolate and purify ACE inhibitory peptides (ACEIPs) from the protein hydrolysate of the marine macroalga Ulva intestinalis. U. intestinalis protein was hydrolyzed by five different proteases (trypsin, pepsin, papain, α-chymotrypsin, alcalase) to prepare peptides; compared with other hydrolysates, the trypsin hydrolysates exhibited the highest ACE inhibitory activity. The hydrolysis conditions were further optimized by response surface methodology (RSM), and the optimum conditions were as follows: pH 8.4, temperature 28.5 °C, enzyme/protein ratio (E/S) 4.0%, substrate concentration 15 mg/mL, and enzymolysis time 5.0 h. After fractionation and purification by ultrafiltration, gel exclusion chromatography and reverse-phase high-performance liquid chromatography, two novel purified ACE inhibitors with IC₅₀ values of 219.35 μM (0.183 mg/mL) and 236.85 μM (0.179 mg/mL) were obtained. The molecular mass and amino acid sequence of the ACE inhibitory peptides were identified as Phe-Gly-Met-Pro-Leu-Asp-Arg (FGMPLDR; MW 834.41 Da) and Met-Glu-Leu-Val-Leu-Arg (MELVLR; MW 759.43 Da) by ultra-performance liquid chromatography-tandem mass spectrometry. A molecular docking study revealed that the ACE inhibitory activities of the peptides were mainly attributable to the hydrogen bond and Zn(II) interactions between the peptides and ACE. The results of this study provide a theoretical basis for the high-valued application of U. intestinalis and the development of food-derived ACE inhibitory peptides.

dentification and molecular docking of novel ACE inhibitory peptides from protein hydrolysates of shrimp waste

The effect of enzymatic hydrolysis by Savinase on the interfacial properties and antihypertensive activity of shrimp waste proteins was evaluated. The physicochemical characterization, interfacial tension, and surface characteristics of shrimp waste protein hydrolysates (SWPH) using different enzyme/substrate (E/S) (SWPH₅ (SWPH using E/S = 5), SWPH₁₅ (SWPH using E/S = 15), and SWPH₄₀ (SWPH using E/S = 40)) were also studied. SWPH₅, SWPH₁₅, and SWPH₄₀ had an isoelectric pH around 2.07, 2.17, and 2.54 respectively. SWPH₅ exhibited the lowest interfacial tension (68.96 mN/m) followed by SWPH₁₅ (69.36 mN/m) and SWPH₄₀ (70.29 mN/m). The in vitro ACE inhibitory activity of shrimp waste protein hydrolysates showed that the most active hydrolysate was obtained using an enzyme/substrate of 15 U/mg (SWPH₁₅). SWPH₁₅ had a lower IC₅₀ value (2.17 mg/mL) than that of SWPH₅ and SWPH₄₀ (3.65 and 5.7 mg/mL, respectively). This hydrolysate was then purified and characterized. Fraction F1 separated by Sephadex G25 column which presents the best ACE inhibition activity was then separated by reversed-phase high performance liquid chromatography. Four ACE inhibitory peptides were identified and their molecular masses and amino acid sequences were determined using ESI-MS and ESI-MS/MS, respectively. The structures of the most potent peptides were SSSKAKKMP, HGEGGRSTHE, WLGHGGRPDHE, and WRMDIDGDIMISEQEAHQR. The structural modeling of anti-ACE peptides from shrimp waste through docking simulations results showed that these peptides bound to ACE with high affinity.

Antihypertensive activity of fish protein hydrolysates and its peptides

The rising interest to utilize nutritionally exorbitant fish proteins has instigated research activities in fish waste utilization. The development of newer technologies to utilize fish waste has fostered use of bioactive value-added products for specific health benefits. Enzymatically obtained Fish Protein Hydrolysate (FPH) is a rich source of biologically active peptides possessing anti-oxidant, anticancer, antimicrobial and anti-hypertensive activity. Isolating natural remedies to combat alarming negative consequences of synthetic drugs has been the new trend in current research promoting identification of antihypertensive peptides from FPH. In this review, we aim to culminate data available to produce antihypertensive peptides from FPH, its composition and potential to be used as a therapeutic agent. These purified peptides are known to be rich in arginine, valine and leucine. Reports reveal peptides with low molecular weight (<1 kDa) and shorter chain length (<20 amino acids) exhibited higher antihypertensive activity. As these peptides have proven Angiotensin Converting Enzyme - I inhibitory activity in vitro and in vivo, their potential to be used as antihypertensive drugs is outrageous. However, current focus on research in the field of molecular docking is necessary to have improved understanding of interaction of the peptides with the enzyme.

Exploration of the molecular interactions between angiotensin-I-converting enzyme (ACE) and the inhibitory peptides derived from hazelnut (Corylus heterophylla Fisch.)

The mechanism of action of food-derived angiotensin-I-converting enzyme (ACE) inhibitory peptides has not been completely elucidated. In the present study, ion-exchange chromatography, gel filtration chromatography, reverse phase-high performance liquid chromatography, and liquid chromatography-electrospray ionization-tandem mass (LC-ESI-MS/MS) were employed for purifying and identifying the ACE inhibitory peptides from hazelnut. To understand the mode of action of these peptides, ACE inhibition kinetics, in vitro and in vivo bioavailability assays, active site analysis, and interaction between the inhibitory peptides and ACE were investigated. The results identified novel ACE inhibitory peptides Ala-Val-Lys-Val-Leu (AVKVL), Tyr-Leu-Val-Arg (YLVR), and Thr-Leu-Val-Gly-Arg (TLVGR) with IC₅₀ values of 73.06, 15.42, and 249.3 μM, respectively. All peptides inhibited the ACE activity via a non-competitive mode. The binding free energies of AVKVL, YLVR, and TLVGR for ACE were -3.46, -6.48, and -7.37 kcal/mol, respectively. The strong inhibition of ACE by YLVR may be attributed to the formation of cation-pi interactions.

Antihypertensive effect of an enzymatic hydrolysate from Styela clava flesh tissue in type 2 diabetic patients with hypertension

BACKGROUND/OBJECTIVES

In this randomized, placebo-controlled, double-blind study, we evaluated the antihypertensive effects of enzymatic hydrolysate from Styela clava flesh tissue in patients with type 2 diabetes mellitus (T2DM) and hypertension.

SUBJECTS/METHODS

S. clava flesh tissue hydrolysate (SFTH) (n = 34) and placebo (n = 22) were randomly allocated to the study subjects. Each subject ingested two test capsules (500 mg) containing powdered SFTH (SFTH group) or placebo capsules (placebo group) during four weeks.

RESULTS

In the SFTH group, systolic and diastolic blood pressure decreased significantly 4 weeks after ingestion by 9.9 mmHg (P < 0.01) and 7.8 mmHg (P < 0.01), respectively. In addition, the SFTH group exhibited a significant decrease in hemoglobin A_1c with a tendency toward improvement in homeostasis model assessment of insulin resistance, triglyceride, apolipoprotein B and plasma insulin levels after 4 weeks. No adverse effects were observed in other indexes, including biochemical and hematological parameters in both groups.

CONCLUSION

The results of our study suggested that SFTH exerts a regulatory, antihypertensive effect in patients with T2DM and hypertension.