Study of the mechanism of antihypertensive peptides VPP and IPP in spontaneously hypertensive rats by DNA microarray analysis

Screening of Potential Angiotensin-Converting Enzyme-Inhibitory Peptides in Squid (Todarodes pacificus) Skin Hydrolysates: Preliminary Study of Its Mechanism of Inhibition

BACKGROUND

Hypertension has been identified as a significant risk factor for cardiovascular disease. Given the prevalence of the adverse effects of angiotensin-converting enzyme-inhibitory (ACEI) drugs, natural and effective alternatives to these medications need to be identified.

METHODS

An investigative study was conducted to assess the ACEI capacity and structural characteristics of enzymatic hydrolysates with varying molecular weights derived from squid skin. The amino acid sequences of the enzymatic digests were analyzed via Nano LC-MS/MS and screened for peptides with ACEI activity using an in silico analysis. Furthermore, molecular docking was employed to investigate the interaction between potential ACEI peptides and ACE.

RESULTS

TPSH-V (MW < 1 kDa) exhibited the highest rate of ACEI, a property attributable to its substantial hydrophobic amino acid content. Additionally, TPSH-V exhibited high temperature and pH stability, indicative of regular ordering in its secondary structure. The binding modes of four potential novel ACEI peptides to ACE were predicted via molecular docking with the sequences of FHGLPAK, IIAPPERKY, RGLPAYE, and VPSDVEF, all of which can bind to the ACE active site via hydrogen bonding, with FHGLPAK, RGLPAYE, and VPSDVEF being able to coordinate with Zn2+.

CONCLUSIONS

Squid skin constitutes a viable resource for the production of ACEI peptides.

Metabolic Syndrome and Biotherapeutic Activity of Dairy (Cow and Buffalo) Milk Proteins and Peptides: Fast Food-Induced Obesity Perspective-A Narrative Review

Metabolic syndrome (MS) is defined by the outcome of interconnected metabolic factors that directly increase the prevalence of obesity and other metabolic diseases. Currently, obesity is considered one of the most relevant topics of discussion because an epidemic heave of the incidence of obesity in both developing and underdeveloped countries has been reached. According to the World Obesity Atlas 2023 report, 38% of the world population are presently either obese or overweight. One of the causes of obesity is an imbalance of energy intake and energy expenditure, where nutritional imbalance due to consumption of high-calorie fast foods play a pivotal role. The dynamic interactions among different risk factors of obesity are highly complex; however, the underpinnings of hyperglycemia and dyslipidemia for obesity incidence are recognized. Fast foods, primarily composed of soluble carbohydrates, non-nutritive artificial sweeteners, saturated fats, and complexes of macronutrients (protein-carbohydrate, starch-lipid, starch-lipid-protein) provide high metabolic calories. Several experimental studies have pointed out that dairy proteins and peptides may modulate the activities of risk factors of obesity. To justify the results precisely, peptides from dairy milk proteins were synthesized under in vitro conditions and their contributions to biomarkers of obesity were assessed. Comprehensive information about the impact of proteins and peptides from dairy milks on fast food-induced obesity is presented in this narrative review article.

Selection of goat β-casein derived ACE-inhibitory peptide SQPK and insights into its effect and regulatory mechanism on the function of endothelial cells

The angiotensin I-converting enzyme (ACE)-inhibitory peptide SQPK was selected by in silico digestion and virtual screening from goat β-casein, and its effect and regulatory mechanism on function of endothelial cells was further evaluated. The results showed that SQPK exhibited relatively good ACE inhibition capacity (IC50 = 452.7 μg/mL). Treatment with 25 μg/mL SQPK for 12 h significantly elevated nitric oxide (NO) production, stimulated eNOS expression (p < 0.05) and affected the transcriptomic profiling of EA. Hy926 cells. In particular, SQPK stimulated the expression of genes encoding inflammatory cytokines (CXCL1/2 and IL6) but depressed encoding mesenchymal markers (FN1 and CNN3). Furthermore, SQPK modified the expression of genes involved in endothelial-to-mesenchymal transition (EndMT). Therefore, the selected peptide SQPK may exert potential protective effects on the function of endothelial cells by inhibiting the EndMT.

Causal associations between dietary habits and CVD: a Mendelian randomisation study

Over the years, numerous observational studies have substantiated that various dietary choices have opposing effects on CVD. However, the causal effect has not yet been established. Thus, we conducted a Mendelian randomisation (MR) analysis to reveal the causal impact of dietary habits on CVD. Genetic variants strongly associated with 20 dietary habits were selected from publicly available genome-wide association studies conducted on the UK Biobank cohort (n 449 210). Summary-level data on CVD were obtained from different consortia (n 159 836-977 323). The inverse-variance weighted method (IVW) was the primary outcome, while MR-Egger, weighted median and MR Pleiotropy RESidual Sum and Outlier were used to assess heterogeneity and pleiotropy. We found compelling evidence of a protective causal effect of genetic predisposition towards cheese consumption on myocardial infarction (IVW OR = 0·67; 95 % CI = 0·544, 0·826; P = 1·784 × 10-4) and heart failure (IVW OR = 0·646; 95 % CI = 0·513, 0·814; P = 2·135 × 10-4). Poultry intake was found to be a detrimental factor for hypertension (IVW OR = 4·306; 95 % CI = 2·158, 8·589; P = 3·416 × 10-5), while dried fruit intake was protective against hypertension (IVW OR = 0·473; 95 % CI = 0·348, 0·642; P = 1·683 × 10-6). Importantly, no evidence of pleiotropy was detected. MR estimates provide robust evidence for a causal relationship between genetic predisposition to 20 dietary habits and CVD risk, suggesting that well-planned diets may help prevent and reduce the risk of CVD.

Recognition of the interaction between the bioactive peptide Val-Pro-Pro and the minimal promoter region of genes SOD and CAT using QCM-D and docking studies

Bioactive peptides are biomolecules involved in very diverse mechanisms in vivo. It has been reported that bioactive peptides play a very important role in the regulation of physiological functions such as oxidative stress, hypertension, cancer and inflammation. It's been reported that the milk derived peptide (VPP) prevents the progress of hypertension in different animal models and human beings with mild hypertension. It has also been shown that oral administration of VPP produces an anti-inflammatory effect in adipose tissue of mouse models. Currently there are no reports on the possible interaction of VPP with the enzymes superoxide dismutase (SOD) and catalase (CAT), the main regulators of oxidative stress. This study analyzes the interaction between VPP and specific domains in the minimal promoter region of the genes SOD and CAT in blood samples of obese children using a QCM-D type piezoelectric biosensor. We also used molecular modeling (docking) to determine the interaction between the peptide VPP and the minimal promoter region of both genes. With QCM-D, we detected the interaction of VPP with the nitrogenous base sequences that comprise the minimal promoter regions of both genes CAT and SOD. These experimental interactions were explained at the atomic level by molecular docking simulations showing how the peptides are capable of reaching the DNA structures by means of hydrogen bonds with favored free energy values. It is possible to conclude that the combined use of docking and QCM-D allows for the determination of the interaction of small peptides (VPP) with specific sequences of genes.

Health-Promoting and Therapeutic Attributes of Milk-Derived Bioactive Peptides

Milk-derived bioactive peptides (BAPs) possess several potential attributes in terms of therapeutic capacity and their nutritional value. BAPs from milk proteins can be liberated by bacterial fermentation, in vitro enzymatic hydrolysis, food processing, and gastrointestinal digestion. Previous evidence suggested that milk protein-derived BAPs have numerous health-beneficial characteristics, including anti-cancerous activity, anti-microbial activity, anti-oxidative, anti-hypertensive, lipid-lowering, anti-diabetic, and anti-osteogenic. In this literature overview, we briefly discussed the production of milk protein-derived BAPs and their mechanisms of action. Milk protein-derived BAPs are gaining much interest worldwide due to their immense potential as health-promoting agents. These BAPs are now used to formulate products sold in the market, which reflects their safety as natural compounds. However, enhanced commercialization of milk protein-derived BAPs depends on knowledge of their particular functions/attributes and safety confirmation using human intervention trials. We have summarized the therapeutic potentials of these BAPs based on data from in vivo and in vitro studies.

Dairy Lactic Acid Bacteria and Their Potential Function in Dietetics: The Food-Gut-Health Axis

Fermented dairy products are the good source of different species of live lactic acid bacteria (LAB), which are beneficial microbes well characterized for their health-promoting potential. Traditionally, dietary intake of fermented dairy foods has been related to different health-promoting benefits including antimicrobial activity and modulation of the immune system, among others. In recent years, emerging evidence suggests a contribution of dairy LAB in the prophylaxis and therapy of non-communicable diseases. Live bacterial cells or their metabolites can directly impact physiological responses and/or act as signalling molecules mediating more complex communications. This review provides up-to-date knowledge on the interactions between LAB isolated from dairy products (dairy LAB) and human health by discussing the concept of the food–gut-health axis. In particular, some bioactivities and probiotic potentials of dairy LAB have been provided on their involvement in the gut–brain axis and non-communicable diseases mainly focusing on their potential in the treatment of obesity, cardiovascular diseases, diabetes mellitus, inflammatory bowel diseases, and cancer.

Antihypertensive potential of fermented milk: the contribution of lactic acid bacteria proteolysis system and the resultant angiotensin-converting enzyme inhibitory peptide

Hypertension has become an increasing health concern given that it is a major risk for cardiovascular disease. Synthetic antihypertensive drugs, including angiotensin-converting enzyme (ACE) inhibitors, effectively control high blood pressure but are associated with unpleasant side effects. Milk fermented by certain lactic acid bacteria (LAB) provides energetic contributions to the management of hypertension, especially the regulation of ACE. LAB are important food-grade microbial organisms that release ACE inhibitory peptides through their unique proteolysis system, which consists of cell-envelope proteinases (CEPs), transporter systems, and intracellular peptidases. Thus, the description of LAB proteolysis system genes and their contributions to ACE inhibitory peptide production is a challenging but promising study. This review provides a survey of LABs with potential ACE inhibitory activity and investigates the research progress of LAB proteolytic systems with an emphasis on the correlation of their components and ACE inhibitory activity. Subsequently, a depiction of the ACE inhibitory peptide action mechanism, structure-activity relationship and bioavailability is presented. The improved functional annotation of LAB proteolytic system genes will provide an excellent framework for future experimental validations of predicted ACE inhibitory activity in fermented milk.

Activity and bioavailability of food protein-derived angiotensin-I-converting enzyme-inhibitory peptides

Angiotensin-I-converting enzyme (ACE) inhibitory peptides are able to inhibit the activity of ACE, which is the key enzymatic factor mediating systemic hypertension. ACE-inhibitory peptides can be obtained from edible proteins and have the function of antihypertension. The amino acid sequences and the secondary structures of ACE-inhibitory peptides determine the inhibitory activities and stability. The resistance of ACE-inhibitory peptides to digestive enzymes and peptidase affect their antihypertensive bioactivity in vivo. In this paper, the mechanism of ACE-inhibition, sources of the inhibitory peptides, structure-activity relationships, stability during digestion, absorption and transportation of ACE-inhibitory peptides, and consumption of ACE-inhibitory peptides are reviewed, which provide guidance to the development of new functional foods and production of antihypertensive nutraceuticals and pharmaceuticals.

Whole Milk and Full-Fat Dairy Products and Hypertensive Risks

Lifestyle modifications in the form of diet and exercise are generally a first-line approach to reduce hypertensive risk and overall cardiovascular disease (CVD) risk. Accumulating research evidence has revealed that consumption of non- and low-fat dairy products incorporated into the routine diet is an effective means to reduce elevated blood pressure and improve vascular functions. However, the idea of incorporating whole-fat or full-fat dairy products in the normal routine diet as a strategy to reduce CVD risk has been met with controversy. The aim of this review is to review both sides of the argument surrounding saturated fat intake and CVD risk from the standpoint of dairy intake. Throughout the review, we examined observational studies on relationships between CVD risk and dairy consumption, dietary intervention studies using non-fat and whole-fat dairy, and mechanistic studies investigating physiological mechanisms of saturated fat intake that may help to explain increases in cardiovascular disease risk. Currently available data have demonstrated that whole-fat dairy is unlikely to augment hypertensive risk when added to the normal routine diet but may negatively impact CVD risk. In conclusion, whole-fat dairy may not be a recommended alternative to non- or low-fat dairy products as a means to reduce hypertensive or overall CVD risk.

Production and characterization of chicken blood hydrolysate with antihypertensive properties

Chicken blood has limited utilization despite its high protein content. Production of a blood hydrolysate exhibiting angiotensin I-converting enzyme (ACE)-inhibitory activity would be means of valorizing chicken blood. The optimized conditions used to produce chicken blood corpuscle hydrolysate (BCH) by Alcalase were 51.1°C, 4% enzyme, and pH 9.6 for 6 h, resulting in a 35.8% degree of hydrolysis and 37.7% ACE inhibition at a peptide concentration of 0.2 mg/mL. The permeate of a 1-kDa membrane, BCH-III, showed a 2.5-fold increase in ACE inhibition compared with that of BCH. BCH-III was resistant to in vitro gastrointestinal digestion, whereas the BCH digesta exhibited an increased ACE-inhibitory activity after digestion. Both BCH and BCH-III were rich in hydrophobic amino acids. A single administration of BCH and BCH-III to spontaneously hypertensive rats at concentrations of 600 and 100 mg/kg, respectively, lowered the systolic blood pressure by -57.7 and -70.9 mmHg, respectively, 6 h after oral administration compared with the control group. The blood pressure-lowering effect of the 600 mg/kg BCH dose was comparable with that of the 100 mg/kg BCH-III dose after 4 wk of oral administration. Both BCH and BCH-III could be developed for use as nutraceutical products with antihypertensive effects.

The ACE2/Ang (1-7)/MasR axis as an emerging target for antihypertensive peptides

Food protein-derived bioactive peptides, particularly antihypertensive peptides, are important constituents of functional foods or nutraceuticals. Most antihypertensive are identified as the inhibitors of angiotensin converting enzyme (ACE), a key enzyme responsible for the generation of angiotensin II (Ang II), which is a vasoconstricting peptide. Hence, ACE has long been used as a universal target to identify antihypertensive peptides. Angiotensin converting enzyme 2 (ACE2), is a homolog of ACE but uses Ang II as its key substrate to produce angiotensin (1-7), exerting vasodilatory activity via the mas receptor (MasR). Therefore, ACE2 functions in the opposite way as ACE and is an emerging novel target for cardiovascular therapy. The potential of food protein-derived bioactive peptides in targeting ACE2 has been rarely explored. While, recently we found that IRW, an egg white ovotransferrin-derived antihypertensive peptide, reduced blood pressure in spontaneously hypertensive rats via the ACE2/Ang (1-7)/MasR axis, indicating a new mechanism of food protein-derived bioactive peptides in reducing blood pressure. The objectives of this review are to summarize the functions of the ACE2/Ang (1-7)/MasR axis and to examine its potential roles in the actions of food protein-derived antihypertensive peptides. The interaction between antihypertensive peptides and the ACE2/Ang (1-7)/MasR axis will also be discussed.

Tripeptides Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP) Regulate the Proliferation and Migration of Vascular Smooth Muscle Cells by Interfering Ang II-Induced Human Umbilical Vein Endothelial Cells Derived EVs Delivering RNAs to VSMCs in the Co-culture Model

Angiotensin II (Ang II), a vasoactive factor in the renin-angiotensin-aldosterone system (RAAS), can regulate vasoconstriction and promote multiple vascular diseases. In this study, the effects of potent antihypertensive peptide Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP) on the proliferation and migration of vascular smooth muscle cells (VSMCs) by extracellular vesicles (EVs) from vascular endothelial cells (VECs) were studied using a cell co-culture model. The VEC-derived EVs were isolated, characterized, and investigated. The present study demonstrated that the EVs from Ang II-induced VECs could promote proliferation, migration, and inflammatory factors (IL-6 increased to 40.75 ± 4.33 pg/mL and IL-1β increased to 28.62 ± 5.42 pg/mL) generation of VSMCs, VPP and IPP exerted discrepant inhibitory effects on this pathway. The EVs with RNase treatment lost the effects on VSMCs, indicating that the RNAs packed into vesicles may be a critical component. These results implied that VPP and IPP could alleviate Ang II-induced vascular dysfunction by modulating the EV-mediated transmission of RNAs between VECs and VSMCs.

Dairy Foods and Dairy Fats: New Perspectives on Pathways Implicated in Cardiometabolic Health

Low-fat and nonfat dairy products have been promoted as part of a healthy dietary pattern by both US dietary guidelines and professional organizations for several decades. The basis for this recommendation stems in part from the putative negative cardiometabolic effects associated with saturated fat consumption. However, as nutrition research has shifted from a single nutrient to a whole-food/dietary pattern approach, the role of dairy foods and dairy fat in the diet-disease relationship is being reexamined. Most observational and experimental evidence does not support a detrimental relationship between full-fat dairy intake and cardiometabolic health, including risks of cardiovascular disease and type 2 diabetes. Indeed, an expanded understanding of the dairy food matrix and the bioactive properties of dairy fats and other constituents suggests a neutral or potentially beneficial role in cardiometabolic health. To consider how consuming dairy foods, including full-fat dairy, is associated with cardiometabolic health, this review provides an innovative perspective on mechanisms that link dairy consumption to 3 main biological systems at the core of metabolic health, the gastrointestinal, hepatic, and vascular systems.

Multifunctional Peptides from Spanish Dry-Cured Pork Ham: Endothelial Responses and Molecular Modeling Studies

Food peptides contain a very wide range of diversified structures, which explains their diverse range of functional activities. Proatherogenic endothelium is related to vasoconstriction, inflammation, and oxidative stress. In this line, four synthetic bioactive peptides from dry-cured pork ham, previously identified according to their Angiotensin I Converting Enzyme (ACE) inhibitory capacity and high bioavailability, were tested. Among them, KPVAAP displayed an estimated IC₅₀ of 59.22 µM for human ACE inhibition, and docking simulations demonstrated the consistency of the noncompetitive binding with the protein. The addition of synthetic peptides to human endothelial cells significantly prevents the expression of genes related to endothelial dysfunction and inflammation (eNOS, ICAM-1, VCAM-1, IL-6) and lowers NF-κB activation (all p < 0.05). In silico dockings showed that the four bioactive peptides interact with the regulatory subunit NEMO of the NF-κB transcription factor at the same site as other characterized inhibitors (CC2-LZ region). This is the first study linking experimental and computational approaches that shows NF-κB to be the target of biopeptides of food origin. These multifunctional peptides from dry-cured pork ham make them good candidates for further research into their therapeutic or preventive use to attenuate the inflammatory atherosclerotic process.

Preparation, Bioavailability, and Mechanism of Emerging Activities of Ile-Pro-Pro and Val-Pro-Pro

Ile-Pro-Pro and Val-Pro-Pro are two most well-known food-derived bioactive peptides, initially identified as inhibitors of angiotensin I-converting enzyme (ACE) from a sample of sour milk. These two peptides were identified in fermented and enzymatic hydrolyzed cow and non-cow (that is, goat, sheep, buffalo, yak, camel, mare, and donkey) milk, as well as sourdough prepared from wheat, rye, and malt. Similar to other bioactive peptides, bioavailability of these peptides is low (about 0.1%), reaching picomolar concentration in human plasma; they showed blood pressure lowering activity in animals and in human, via improved endothelial function, activation of ACE2, and anti-inflammatory property. Emerging bioactivities of these two peptides toward against metabolic syndrome and bone-protection received limited attention, but may open up new applications of these peptides as functional food ingredients. Further studies are warranted to determine the best source as well as to identify novel enzymes (particularly from traditional fermented milk products) to improve the efficiency of production, to characterize possible peptide receptors using a combination of omics technology with molecular methods to understand if these two peptides act as signal-like molecules, to improve their bioavailability, and to explore new applications based on emerging bioactivities.

Effects of full-fat dairy products on subclinical vascular function in adults with elevated blood pressure: a randomized clinical trial

BACKGROUND

High consumption of low- and non-fat dairy products improves vascular dysfunction associated with elevated arterial blood pressure (BP). Currently, it is unknown if conventional full-fat dairy products improve vascular functions.

OBJECTIVES

To determine if adding whole milk and full-fat dairy products to the normal routine diet improves vascular function in adults with elevated BP.

DESIGN

Sixty adults (age ± SEM; 58 ± 2 years) with elevated BP (systolic/diastolic; 120-159/ < 99 mmHg) were randomized into a controlled crossover intervention trial consisting of two 4-week dietary periods. The high dairy condition consisted of adding four daily servings of whole milk or full-fat dairy products to the normal diet and eliminated all dairy intake during the control (no dairy) condition. A 2-week washout period separated the dietary conditions.

RESULTS

Carotid-femoral pulse wave velocity (cfPWV) did not differ significantly between high dairy (11.3 ± 0.3 versus 10.9 ± 0.3 m/sec) and no dairy conditions (11.2 ± 0.3 versus 11.0 ± 0.3 m/sec). The results were consistent when ultrasound-derived vascular distension measures (arterial compliance, beta-stiffness index, and elastic modulus) were evaluated. Cardiovagal baroreceptor sensitivity (via Valsalva maneuver) demonstrated no significant difference for either dietary condition. Brachial arterial flow-mediated dilation (FMD) did not differ significantly during the high dairy (5.7 ± 0.5 versus 5.4 ± 0.6%) and no dairy conditions (6.5 ± 0.5 versus 5.6 ± 0.6%).

CONCLUSIONS

The solitary addition of whole milk and full-fat dairy products has no effect on subclinical vascular function in adults with elevated BP.

Milk-Derived Tripeptides IPP (Ile-Pro-Pro) and VPP (Val-Pro-Pro) Enhance Insulin Sensitivity and Prevent Insulin Resistance in 3T3-F442A Preadipocytes

There is great interest in developing naturally derived compounds, especially bioactive peptides with potential insulin sensitizing effects and/or preventing insulin resistance. Previously, we showed adipogenic and insulin mimetic actions of IPP (Ile-Pro-Pro) and VPP (Val-Pro-Pro), the milk-derived tripeptides on cultured preadipocytes, in addition to their previously characterized antihypertensive and anti-inflammatory functions. However, the effect of these peptides on insulin signaling is not known. Therefore, we examined IPP and VPP effects on insulin signaling in preadipocytes, a well-established model for studying insulin signaling. Our results suggested both peptides enhanced insulin signaling and contributed toward the prevention of insulin resistance in the presence of tumor necrosis factor (TNF). Inhibition of inflammatory mediator NF-kB under TNF stimulation was a likely contributor to the prevention of insulin resistance. VPP further enhanced the expression of glucose transporter 4 (GLUT4) in adipocytes and restored glucose uptake in TNF-treated adipocytes. Our data suggested the potential of these peptides in the management of conditions associated with impairments in insulin signaling.

Mechanistic Pathways Underlying the Antihypertensive Effect of Fermented Milk with Lactococcus lactis NRRL B-50571 in Spontaneously Hypertensive Rats

It has been reported that fermented milk (FM) with Lactococcus lactis NRRL B-50571 had an antihypertensive effect in spontaneously hypertensive rats (SHR) and prehypertensive subjects. Therefore, the objective of the present study was to evaluate the possible mechanisms involved (angiotensin converting enzyme inhibition (ACEI), enhancement of nitric oxide production, antioxidant activity and opioid effect), in the antihypertensive effect of FM with SHR. First, twenty one SHR were randomized into three groups to either receive in a single-oral dose of purified water (negative control), FM, or naloxone (opioid receptor antagonist) + FM. In a parallel study, twenty seven SHR were randomized into three groups to either receive ad libitum purified water (negative control), Captopril or FM. After six weeks of treatment ACEI activity, enhancement of nitric oxide production, and antioxidant activity were evaluated in plasma. Results indicated that opioid receptors were not involved in the hypotensive effect of FM. However, ACEI activity (94 U/L), the oxidative stress index (malondialdehyde/catalase + glutathione peroxidase) 0.9, and nitric oxide in plasma (4.4 ± 1.3 U/L), were significantly different from the negative control, and not significantly different from the Captopril group. Thus, these results suggested that these mechanisms are involved in the hypotensive effect of FM.

Structure-informed detection and quantification of peptides in food and biological fluids

Peptides with biological properties, that is, bioactive peptides, are a class of biomolecules whose health-promoting properties are increasingly being exploited in food and health products. However, research on targeted techniques for the detection and quantification of these peptides is still in its infancy. Such information is needed in order to enhance the biological and chemometric characterization of peptides and their subsequent application in the functional food and pharmaceutical industries. In this review, the role of classic techniques such as electrophoretic, chromatographic, and peptide mass spectrometry in the structure-informed detection and quantitation of bioactive peptides are discussed. Prospects for the use of aptamers in the characterization of bioactive peptides are also discussed. PRACTICAL APPLICATIONS: Although bioactive peptides have huge potential applications in the functional foods and health area, there are limited techniques in enhancing throughput detection, quantification, and characterization of these peptides. This review discusses state-of-the-art techniques relevant in complementing bioactive detection and profiling irrespective of the small number of amino acid units. Insights into challenges, possible remedies and prevailing areas requiring thorough research in the extant literature for food chemists and biotechnologists are also presented.

Peptides Derived from Foods as Supportive Diet Components in the Prevention of Metabolic Syndrome

Metabolic syndrome (MSyn) includes physiological, biochemical, clinical, and metabolic abnormalities, leading to an increase in health problems like obesity, dyslipidemia, cardiovascular diseases, and diabetes, which contribute to an increase in mortality rate. One of the main factors having a key impact on our health is the food we consume. Thus, scientists work towards the discovery of novel bioactive compounds with therapeutic potential to address MSyn. According to scientific reports, peptides derived from food proteins exhibit bioactivities important for the prevention of MSyn diseases; that is, they regulate blood pressure and glycemia; reduce cholesterol level and body mass; and scavenge free radicals. The aim of this review is to study the potential role of peptides in the prevention of MSyn. Particularly peptides which exhibit the following activities: antihypertensive [angiotensin-converting enzyme (ACE) inhibition (EC 3.4.15.1)], antidiabetic [dipeptidyl peptidase IV (DPP-IV) (EC 3.4.14.5)/α-glucosidase (EC 3.2.1.20)/α-amylase (EC 3.2.1.1) inhibition)], cholesterol level reduction, antioxidative, and obesity prevention, were studied. If possible, special attention is paid in the review to the bioactivities of peptides that were measured in vivo. Some examples of peptides showing dual or multiple action against MSyn targets are presented. Moreover, using the database of bioactive peptide sequences (BIOPEP) we made a list of peptides serving simultaneous functions in counteracting MSyn dysfunctions. Such an approach may simplify the discovery of MSyn preventive peptides, as well as highlight some of them as potent bioactive ingredients that may be incorporated into foods. Moreover, the research strategy involving the in silico and in vitro/in vivo methodologies may be useful in the production of food protein hydrolysates supporting the treatment of MSyn dysfunctions.

Formulation, Characterization and Stability Assessment of a Food-Derived Tripeptide, Leucine-Lysine-Proline Loaded Chitosan Nanoparticles

The chicken- or fish-derived tripeptide, leucine-lysine-proline (LKP), inhibits the angiotensin converting enzyme and may be used as an alternative treatment for prehypertension. However, it has low permeation across the small intestine. The formulation of LKP into a nanoparticle (NP) has the potential to address this issue. LKP-loaded NPs were produced using an ionotropic gelation technique, using chitosan (CL113). Following optimization of unloaded NPs, a mixture amount design was constructed using variable concentration of CL113 and tripolyphosphate at a fixed LKP concentration. Resultant particle sizes ranged from 120 to 271 nm, zeta potential values from 29 to 37 mV, and polydispersity values from 0.3 to 0.6. A ratio of 6:1 (CL113:TPP) produced the best encapsulation of approximately 65%. Accelerated studies of the loaded NPs indicated stability under normal storage conditions (room temperature). Cytotoxicity assessment showed no significant loss of cell viability and in vitro release studies indicated an initial burst followed by a slower and sustained release.

Antihypertensive peptides from animal products, marine organisms, and plants

Bioactive peptides from food proteins exert beneficial effects on human health, such as angiotensin-converting enzyme (ACE) inhibition and antihypertensive activity. Several studies have reported that ACE-inhibitory peptides can come from animal products, marine organisms, and plants-derived by hydrolyzing enzymes such as pepsin, chymotrypsin, and trypsin-and microbial enzymes such as alcalase, thermolysin, flavourzyme, and proteinase K. Different ACE-inhibitory effects are closely related with different peptide sequences and molecular weights. Sequences of ACE-inhibitory peptides are composed of hydrophobic (proline) and aliphatic amino acids (isoleucine and leucine) at the N-terminus. As result of this review, we assume that low molecular weight peptides have a greater ACE inhibition because lower molecular weight peptides have a higher absorbency in the body. Therefore, the ACE-inhibitory effect is closely related with the degree of enzymatic hydrolysis and the composition of the peptide sequence.

A Novel Antihypertensive Derived from Adlay (Coix larchryma-jobi L. var. ma-yuen Stapf) Glutelin

Our previous studies have shown that Coix glutelin pepsin hydrolysate can effectively inhibit angiotensin converting enzyme (ACE) activity in vitro. The main purpose of this study was to obtain potent anti-hypertensive peptides from Coix glutelin. The Coix glutelin hydrolysates (CGH) were prepared by pepsin catalysis and further separated by an ultrafitration (UF) system, gel filtration chromatography (GFC) and reversed-phase high performance liquid chromatography (RP-HPLC). As a result, the sub-fraction F5-3 had the highest ACE-inhibitory activity. Six ACE inhibitory peptides were identifiedusing nano-liquid chromatography coupled to tandem mass spectrometry. The most potent peptide GAAGGAF (IC50 = 14.19 μmol·L-1) was finally obtained by further molecular simulation screening and a series of division and optimization. Single oral administration of synthesized GAAGGAF at 15 mg/kg body weight (BW) in spontaneously hypertensively rats (SHR) could reduce the systolic blood pressure (SBP) around 27.50 mmHg and blood pressure-lowering effect lasted for at least 8 h. The study demonstrated for the first time that the ACE inhibitory peptide GAAGGAF from Coix glutelin has a significant antihypertensive effect, and it could be a good natural ingredient for pharmaceuticals against hypertension and the related diseases.

Modulatory Effects of Egg White Ovotransferrin-Derived Tripeptide IRW (Ile-Arg-Trp) on Vascular Smooth Muscle Cells against Angiotensin II Stimulation

The renin angiotensin system (RAS) is a key mediator of blood pressure regulation. Angiotensin II (Ang II), the active component of RAS, is a potent vasoconstrictor that also causes abnormal proliferation, oxidative stress, and inflammation in vascular smooth muscle cells (VSMCs) that contribute to atherosclerotic changes. Egg white ovotransferrin-derived tripeptide IRW (Ile-Arg-Trp) was previously shown to exert antihypertensive effect by reducing Ang II synthesis as well as endothelial cell inflammation and endothelial dysfunction. However, the effects of IRW on VSMCs are still unclear. In the present study, we evaluated the antiproliferative, antioxidant, and anti-inflammatory effects of IRW on VSMCs in the presence of Ang II stimulation. It was found that IRW treatment could attenuate Ang II-stimulated proliferation, superoxide production, and inflammation in VSMCs. These beneficial effects appeared to involve modulation of the NF-κB pathway. These findings could further our understanding on the antihypertensive mechanism of IRW beyond vascular endothelium.

Acute dairy milk ingestion does not improve nitric oxide-dependent vasodilation in the cutaneous microcirculation

In epidemiological studies, chronic dairy milk consumption is associated with improved vascular health and reduced age-related increases in blood pressure. Although milk protein supplementation augments conduit artery flow-mediated dilation, whether or not acute dairy milk intake may improve microvascular function remains unclear. We hypothesised that dairy milk would increase direct measurement of endothelial nitric oxide (NO)-dependent cutaneous vasodilation in response to local skin heating. Eleven men and women (61 (sem 2) years) ingested two or four servings (473 and 946 ml) of 1 % dairy milk or a rice beverage on each of 4 separate study days. In a subset of five subjects, an additional protocol was completed after 473 ml of water ingestion. Once a stable blood flow occurred, 15 mm-N G -nitro-l-arginine methyl ester was perfused (intradermal microdialysis) to quantify NO-dependent vasodilation. Red-blood-cell flux (RBF) was measured by laser-Doppler flowmetry, and cutaneous vascular conductance (CVC=RBF/mean arterial pressure) was calculated and normalised to maximum (%CVCmax; 28 mm-sodium nitroprusside). Full expression of cutaneous vasodilation was not different among dairy milk, rice beverage and water, and there was no effect of serving size on the total vasodilatory response. Contrary to our hypothesis, NO-dependent vasodilation was lower for dairy milk than rice beverage (D: 49 (sem 5), R: 55 (sem 5) %CVCmax; P<0·01). Acute dairy milk ingestion does not augment NO-dependent vasodilation in the cutaneous microcirculation compared with a rice beverage control.

Influence of the Lactotripeptides Isoleucine-Proline-Proline and Valine-Proline-Proline on Systolic Blood Pressure in Japanese Subjects: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

The lactotripeptides isoleucine–proline–proline (IPP) and valine–proline–proline (VPP) have been shown to decrease systolic blood pressure (SBP) in several populations, but the size of the effect varies among studies. We performed a meta-analysis including all published studies to evaluate the SBP-lowering effect of IPP/VPP in Japanese subjects more comprehensively.

Methods and Findings

Eligible randomized controlled trials were searched for within four bibliographic databases, including two Japanese ones. Eighteen studies (including a total of 1194 subjects) were included in the meta-analysis. A random effect model using the restricted maximum likelihood (REML) estimator was used for the analysis. The analysis showed that consumption of IPP/VPP induced a significant reduction in SBP as compared with placebo in Japanese subjects, with an estimated effect of -5.63 mm Hg (95% CI, -6.87 to -4.39, P<0.0001) and no evidence of publication bias. A significant heterogeneity between series was evident, which could be explained by a significant influence of the baseline blood pressure status of the subjects, the effect of IPP/VPP on SBP being stronger in hypertensive subjects (-8.35 mm Hg, P<0.0001) than in non-hypertensive subjects (-3.42mm Hg, P<0.0001). Furthermore, the effect of IPP/VPP on SBP remained significant when limiting the analysis to series that tested the usual doses of IPP/VPP consumed daily (below 5 mg/d), with estimated effects of -6.01 mm Hg in the overall population and -3.32 mm Hg in non-hypertensive subjects.

Conclusions

Results from this meta-analysis show that IPP/VPP lactotripeptides can significantly reduce office SBP in Japanese subjects with or without overt hypertension, and for doses that can potentially be consumed as an everyday supplement. This suggests that these peptides could play a role in controlling blood pressure in Japanese subjects. The systematic review protocol was published on the PROSPERO register (CRD42014014322).

Alteration of Gene Expression Profile in Kidney of Spontaneously Hypertensive Rats Treated with Protein Hydrolysate of Blue Mussel (Mytilus edulis) by DNA Microarray Analysis

Marine organisms are rich sources of bioactive components, which are often reported to have antihypertensive effects. However, the underlying mechanisms have yet to be fully identified. The aim of this study was to investigate the antihypertensive effect of enzymatic hydrolysis of blue mussel protein (HBMP) in rats. Peptides with in vitro ACE inhibitory activity were purified from HBMP by ultrafiltration, gel filtration chromatography and reversed-phase high performance liquid chromatography. And the amino acid sequences of isolated peptides were estimated to be Val-Trp, Leu-Gly-Trp, and Met-Val-Trp-Thr. To study its in vivo action, spontaneously hypertensive rats (SHRs) were orally administration with high- or low-dose of HBMP for 28 days. Major components of the renin-angiotensin (RAS) system in serum of SHRs from different groups were analyzed, and gene expression profiling were performed in the kidney of SHRs, using the Whole Rat Genome Oligonucleotide Microarray. Results indicated although genes involved in RAS system were not significantly altered, those related to blood coagulation system, cytokine and growth factor, and fatty acids metabolism were remarkablely changed. Several genes which were seldom reported to be implicated in pathogenesis of hypertension also showed significant expression alterations after oral administration of HBMP. These data provided valuable information for our understanding of the molecular mechanisms that underlie the potential antihypertensive activities of HBMP, and will contribute towards increased value-added utilization of blue mussel protein.

Peptides-Derived from Thai Rice Bran Improves Endothelial Function in 2K-1C Renovascular Hypertensive Rats

In recent years, a number of studies have investigated complementary medical approaches to the treatment of hypertension using dietary supplements. Rice bran protein hydrolysates extracted from rice is a rich source of bioactive peptides. The present study aimed to investigate the vasorelaxation and antihypertensive effects of peptides-derived from rice bran protein hydrolysates (RBP) in a rat model of two kidney-one clip (2K-1C) renovascular hypertension. 2K-1C hypertension was induced in male Sprague-Dawley rats by placing a silver clip around the left renal artery, whereas sham-operated rats were served as controls. 2K-1C and sham-operated rats were intragastrically administered with RBP (50 mg kg(-1) or 100 mg kg(-1)) or distilled water continuously for six weeks. We observed that RBP augmented endothelium-dependent vasorelaxation in all animals. Administration of RBP to 2K-1C rats significantly reduced blood pressure and decreased peripheral vascular resistance compared to the sham operated controls (p < 0.05). Restoration of normal endothelial function and blood pressure was associated with reduced plasma angiotensin converting enzyme (ACE), decreased superoxide formation, reduced plasma malondialdehyde and increased plasma nitrate/nitrite (p < 0.05). Up-regulation of eNOS protein and down-regulation of p47phox protein were found in 2K-1C hypertensive rats-treated with RBP. Our results suggest that RBP possesses antihypertensive properties which are mainly due to the inhibition of ACE, and its vasodilatory and antioxidant activity.

Egg ovotransferrin-derived ACE inhibitory peptide IRW increases ACE2 but decreases proinflammatory genes expression in mesenteric artery of spontaneously hypertensive rats

Scope

Egg ovotransferrin‐derived angiotensin converting enzyme (ACE) inhibitory peptide IRW was previously shown to reduce blood pressure in spontaneously hypertensive rats through reduced vascular inflammation and increased nitric oxide‐mediated vasorelaxation. The main objective of the present study was to investigate the molecular mechanism of this peptide through transcriptome analysis by RNAseq technique.

Methods and results

Total RNA was extracted from kidney and mesenteric arteries; the RNAseq libraries (from untreated and IRW‐treated groups) were constructed and subjected to sequence using HiSeq 2000 system (Illumina) system. A total of 12 764 and 13 352 genes were detected in kidney and mesenteric arteries, respectively. The differentially expressed (DE) genes between untreated and IRW‐treated groups were identified and the functional analysis through ingenuity pathway analysis revealed a greater role of DE genes identified from mesenteric arteries than that of kidney in modulating various cardiovascular functions. Subsequent qPCR analysis further confirmed that IRW significantly increased the expression of ACE‐2, ABCB‐1, IRF‐8, and CDH‐1 while significantly decreased the expression ICAM‐1 and VCAM‐1 in mesenteric arteries.

Conclusion

Our research showed for the first time that ACE inhibitory peptide IRW could contribute to its antihypertensive activity through increased ACE2 and decreased proinflammatory genes expression.

Milk-derived tripeptides IPP (Ile-Pro-Pro) and VPP (Val-Pro-Pro) promote adipocyte differentiation and inhibit inflammation in 3T3-F442A cells

Milk derived tripeptides IPP (Ile-Pro-Pro) and VPP (Val-Pro-Pro) have shown promise as anti-hypertensive agents due to their inhibitory effects on angiotensin converting enzyme (ACE). Due to the key inter-related roles of hypertension, chronic inflammation and insulin resistance in the pathogenesis of metabolic syndrome, there is growing interest in investigating established anti-hypertensive agents for their effects on insulin sensitivity and inflammation. In this study, we examined the effects of IPP and VPP on 3T3-F442A murine pre-adipocytes, a widely used model for studying metabolic diseases. We found that both IPP and VPP induced beneficial adipogenic differentiation as manifested by intracellular lipid accumulation, upregulation of peroxisome proliferator-activated receptor gamma (PPARγ) and secretion of the protective lipid hormone adiponectin by these cells. The observed effects were similar to those induced by insulin, suggesting potential benefits in the presence of insulin resistance. IPP and VPP also inhibited cytokine induced pro-inflammatory changes such as reduction in adipokine levels and activation of the nuclear factor kappa B (NF-κB) pathway. Taken together, our findings suggest that IPP and VPP exert insulin-mimetic adipogenic effects and prevent inflammatory changes in adipocytes, which may offer protection against metabolic disease.

Unraveling the mechanisms of action of lactoferrin-derived antihypertensive peptides: ACE inhibition and beyond

The characterization of lactoferrin-derived antihypertensive peptides shows that they might act on several molecular targets.

Molecular targets of antihypertensive peptides: understanding the mechanisms of action based on the pathophysiology of hypertension

There is growing interest in using functional foods or nutraceuticals for the prevention and treatment of hypertension or high blood pressure. Although numerous preventive and therapeutic pharmacological interventions are available on the market, unfortunately, many patients still suffer from poorly controlled hypertension. Furthermore, most pharmacological drugs, such as inhibitors of angiotensin-I converting enzyme (ACE), are often associated with significant adverse effects. Many bioactive food compounds have been characterized over the past decades that may contribute to the management of hypertension; for example, bioactive peptides derived from various food proteins with antihypertensive properties have gained a great deal of attention. Some of these peptides have exhibited potent in vivo antihypertensive activity in both animal models and human clinical trials. This review provides an overview about the complex pathophysiology of hypertension and demonstrates the potential roles of food derived bioactive peptides as viable interventions targeting specific pathways involved in this disease process. This review offers a comprehensive guide for understanding and utilizing the molecular mechanisms of antihypertensive actions of food protein derived peptides.

Asn-Trp dipeptides improve the oxidative stress and learning dysfunctions ind-galactose-induced BALB/c mice

Asn-Trp (NW) interventions for 4 weeks can attenuate the oxidative stress and learning dysfunctions induced by dailyd-galactose subcutaneous injection for 8 weeks.

Do the lactotripeptides isoleucine-proline-proline and valine-proline-proline reduce systolic blood pressure in European subjects? A meta-analysis of randomized controlled trials

BACKGROUND

The milk-derived peptides isoleucine–proline–proline (IPP) and valine–proline– proline (VPP) have been shown to reduce systolic blood pressure (SBP). This decrease is convincingly shown in subjects of Asian origin, but less consistent results have been obtained in European populations.

METHODS

A meta-analysis was conducted in accord with the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) requirements, to assess the effect of IPP and VPP on SBP in Europeans, and to explore some determinants of this effect.

RESULTS

Ninety-one publications on the effect of IPP and VPP on SBP in Europeans were identified, and 14 trials with 15 sets of data (n = 1,306) met the inclusion criteria for the meta-analysis. A random-effects model (using the restricted maximum likelihood (REML) estimator) was used for the analysis. Although not all individual trials showed a statistically significant effect of IPP or VPP in reducing SBP, the combination of all data for the two peptides yielded a statistically significantly greater effect for IPP/VPP than for placebo. The decrease in SBP with IPP/VPP was 1.28mm Hg (95% CI, –2.09 to –0.48, P = 0.0017) and the decrease in diastolic BP (DBP) was 0.59mm Hg (95% CI, –1.18 to –0.01, P = 0.047). There was no evidence in the meta-analysis of any publication bias or of heterogeneity (P = 0.13). Among other features, a significant effect was seen for age, with each additional year of age reducing the effect on SBP by 0.09mm Hg. This might be related to isolated systolic hypertension, a condition often encountered in the elderly, who may be poorly responsive to first-line treatments for hypertension.

CONCLUSION

The peptides IPP and VPP are effective in moderately reducing SBP in European subjects, as is known for Asian populations. These two peptides could therefore have a role in controlling blood pressure (BP), a prospect that merits their further study.

Review: Production and functionality of active peptides from milk

In recent years, research on the production of active peptides obtained from milk and their potential functionality has grown, to a great extent. Bioactive peptides have been defined as specific protein fragments that have a positive impact on body functions or conditions, and they may ultimately have an influence on health. Individual proteins of casein or milk-derived products such as cheese and yogurt have been used as a protein source to study the isolation and activity of peptides with several applications. Currently, the milk whey waste obtained in the production of cheese also represents a protein source from which active peptides could be isolated with potential industrial applications. The active properties of milk peptides and the results found with regard to their physiological effects have led to the classification of peptides as belonging to the group of ingredients of protein nature, appropriate for use in functional foods or pharmaceutical formulations. In this study, the main peptides obtained from milk protein and the past research studies about its production and biological activities will be explained. Second, an analysis will be made on the methods to determinate the biological activities, the separation of bioactive peptides and its structure identification. All of these form the base required to obtain synthetic peptides. Finally, we explain the experimental animal and human trials done in the past years. Nevertheless, more research is required on the design and implementation of equipment for the industrial production and separation of peptides. In addition, different authors suggest that more emphasis should therefore be given to preclinical studies, proving that results are consistent and that effects are demonstrated repeatedly by several research human groups.

Role of dietary proteins and peptides in cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of death for both men and women in the United States and most other countries. Therefore, a disease of such wide-ranging impact calls for the development of multiple viable strategies for prevention. Diet plays an important role in the development of the major risk factors of CVD such as low-grade systemic inflammation, hypertension, obesity, diabetes and atherosclerosis, the most significant. Thus, diet-based methods of prevention would not only be more feasible, but ultimately more cost-effective than relying on drugs to combat this condition. In recent years, peptides derived from either animal or plant sources have been found to have various bioactive properties. Nevertheless, their potential impact on inflammation and prevention of atherosclerosis has not been fully explored, particularly at the molecular level. In this review, the most current scientific information from in vitro, in vivo and clinical studies on the role of dietary proteins and peptides on CVD has been summarized and discussed.