Basic and recent advances in marine antihypertensive peptides: Production, structure-activity relationship and bioavailability

A strategy to boost xanthine oxidase and angiotensin converting enzyme inhibitory activities of peptides via molecular docking and module substitution

Molecular docking and activity evaluation screened the dipeptide module GP with low xanthine oxidase (XOD) inhibitory activity and modules KE and KN with high activity, and identified them as low- and high-contribution modules, respectively. We hypothesized the substitution of low-contribution modules in peptides with high contributions would boost their XOD inhibitory activity. In the XOD inhibitory peptide GPAGPR, substitution of GP with both KE and KN led to enhanced affinity between the peptides and XOD. They also increased XOD inhibitory activity (26.4% and 10.3%) and decreased cellular uric acid concentrations (28.0% and 10.4%). RNA sequencing indicated that these improvements were attributable to the inhibition of uric acid biosynthesis. In addition, module substitution increased the angiotensin-converting enzyme inhibitory activity of GILRP and GAAGGAF by 84.8% and 76.5%. This study revealed that module substitution is a feasible strategy to boost peptide activity, and provided information for the optimization of hydrolysate preparation conditions.

Impact of cod skin peptide-ι-carrageenan conjugates prepared via the Maillard reaction on the physical and oxidative stability of Antarctic krill oil emulsions

This research aimed to construct an emulsifier by the Maillard reaction at various times using cod fish skin collagen peptide (CSCP) and ι-carrageenan (ι-car) to stabilize an Antarctic krill oil (AKO) emulsion. This emulsion was then investigated for physicochemical stability, oxidative stability, and gastrointestinal digestibility. The emulsion stability index and emulsifying activity index of Maillard reaction products (MRPs) were increased by 36.32 % and 66.30 %, respectively, at the appropriate graft degree (25.58 %) compared with the mixture of ι-car and CSCP. In vitro digestibility suggested the higher release of free fatty acids (FFAs) of 10d-MRPs-AKO-emulsion, and the highest bioavailability of AST in 10d-MRPs-AKO was found to be 28.48 %. The findings of this study showed the potential of MRPs to improve peptide function, serve as delivery vehicles for bioactive chemicals, and possibly serve as a valuable emulsifier to be used in the food industry.

Characterization of fermented pomegranate juice: ACE inhibitory activity under in vitro digestion, antioxidant capacity, phenolics composition, chemical properties and sensory evaluation

Consuming pomegranate juice (PJ) is beneficial for hypertensive regulation because of the phenolic compounds in PJ and their inhibitory activity on angiotensin-I-converting enzyme (ACE). To better utilize bioactive function of food, microorganism fermentation has been adopted to alter phenolic metabolism. This study confirms that even under in vitro digestion, fermented PJ (FPJ) maintains higher ACE inhibitory activity than that of PJ. The main phenolic compounds in PJ were compared either under fermentation or in vitro digestion. This study finds that fermentation promotes antioxidant capacity of PJ. The chemical properties of FPJ are evaluated and the corresponding relationship with bioactivities is analyzed. A sensory evaluation comparison is conducted between FPJ and PJ, furnishing interesting information for consumers. This study highlights the relationship between ACE inhibitory activity of PJ and phenolic composition under fermentation and in vitro digestion, providing novel insights for diet regulation of phenolic-rich FPJ in ACE inhibition therapy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01388-w.

Two novel angiotensin I-converting enzyme inhibitory peptides from garlic protein: In silico screening, stability, antihypertensive effects in vivo and underlying mechanisms

This study aimed to screen novel angiotensin I-converting enzyme (ACE) inhibitory peptides from garlic proteins and to explore their underlying antihypertensive mechanisms in vivo. After simulated hydrolysis and in silico screening, two novel peptides (MGR and HDCF) were obtained with the highest ACE inhibitory activity (IC50 of 4.50 μM and 26.38 μM) and acted as competitive inhibitors. They interacted with key residues in the ACE receptor mainly through hydrogen bonding and exhibited excellent stability against high temperature, extreme pH, and gastrointestinal digestion. In spontaneously hypertensive rats, MGR and HDCF effectively lowered blood pressure after single or continuous treatments. This was mainly achieved by balancing the renin-angiotensin system, improving renal and cardiac impairment, and regulating endothelial dysfunction. These findings suggested that garlic proteins were potentially suitable materials to prepare ACE inhibitory peptides and provided two promising candidates for ACE inhibition as functional food ingredients.

The targeted development of collagen-active peptides based on composite enzyme hydrolysis: a study on the structure-activity relationship

Fish collagen, derived from sustainable sources, offers a valuable substrate for generating peptides with diverse biofunctionalities. In this study, alkaline, papain, and ginger protease were used to enzymatically hydrolyze fish skin collagen. The peptide molecular weight distribution and sequence were measured using HPLC and ICP-MS-MS, with papain/alkaline protease (AP) and papain/alkaline/ginger protease (APG) hydrolyzed samples compared. As the results showed, the incorporation of ginger protease was useful for increasing the degree of hydrolysis, with the content of <400 Da peptides increasing from 49.82% to 58.56%. The identified peptide sequence in the APG sample had more proline at the C-terminal. The peptides were separated into two components (different in molecular weight) using gel column chromatography. The molecular weight distribution, amino acid composition, ACE inhibitory activity, and fibroblast proliferation activity of the collected components were measured. In comparison, the contents of proline and hydroxyproline in the larger peptides decreased obviously after combined hydrolysis by ginger protease, reflecting the formation of a peptide sequence of smaller molecular weight containing glycine and hydroxyproline. The combined hydrolysis of ginger protease was beneficial for the improvement of the ACE inhibitory activity of the sample. However, the fibroblast proliferation activity of AP was higher than that of APG, indicating that further hydrolysis by ginger protease may destroy the hydroxyproline at the end of the peptide sequence. This study proposed a creative directional hydrolysis method and provided practical guidance for the production of collagen peptides with enhanced functional activity.

Identification of novel angiotensin converting enzyme (ACE) inhibitory peptides from Pacific saury: In vivo antihypertensive effect and transport route

Nature food-derived angiotensin converting enzyme inhibitory peptides (ACEIPs) can be potent and safe therapeutics for many medical illnesses, particularly hypertension. In this study, novel ACEIPs were screened and identified from Pacific saury by bio-activity guided approach through ultrafiltration membrane, Sephadex G-25 and RP-HPLC. The antihypertensive effect of ultrafiltration fraction was confirmed with spontaneous hypertensive rats' (SHRs) model. The peptides sequences of which gave the best activity was identified by Q-Orbitrap-MS/MS and selectively synthesized based on the binding energy of molecular docking. Five peptides VVLASLK, LTLK, LEPWR, ELPPK and LPTEK were synthesized, and the peptide LEPWR (IC50 = 99.5 μM) showed the best ACE inhibitory ability. Furthermore, LEPWR against ACE in a mixed competitive pattern and formed six hydrogen bonds with ACE. Additionally, the apparent permeability coefficient (Papp) of LEPWR was 3.56 ± 0.14 × 10-6 cm/s and paracellular transport across tight junctions was the main pathway across the Caco-2 monolayer. Therefore, the Pacific saury is a good material to prepare ACEIPs, but antihypertensive mechanism of peptide LEPWR on SHRs needs further investigation.

Affinity Purification and Molecular Characterization of Angiotensin-Converting Enzyme (ACE)-Inhibitory Peptides from Takifugu flavidus

An affinity chromatography filler of CNBr-activated Sepharose 4B-immobilized ACE was used to purify ACE-inhibitory peptides from Takifugu flavidus protein hydrolysate (<1 kDa). Twenty-four peptides with an average local confidence score (ALC) ≥ 80% from bounded components (eluted by 1 M NaCl) were identified by LC-MS/MS. Among them, a novel peptide, TLRFALHGME, with ACE-inhibitory activity (IC50 = 93.5 µmol·L-1) was selected. Molecular docking revealed that TLRFALHGME may interact with the active site of ACE through H-bond, hydrophobic, and electrostatic interactions. The total binding energy (ΔGbinding) of TLRFALHGME was estimated to be -82.7382 kJ·mol-1 by MD simulations, indicating the favorable binding of peptides with ACE. Furthermore, the binding affinity of TLRFALHGME to ACE was determined by surface plasmon resonance (SPR) with a Kd of 80.9 µmol, indicating that there was a direct molecular interaction between them. TLRFALHGME has great potential for the treatment of hypertension.

Discovery of ACE Inhibitory Peptides Derived from Green Coffee Using In Silico and In Vitro Methods

Inhibition of angiotensin-I converting enzyme (ACE) is an important means of treating hypertension since it plays an important regulatory function in the renin-angiotensin system. The aim of this study was to investigate the ACE inhibitory effect of bioactive peptides from green coffee beans using in silico and in vitro methods. Alcalase and thermolysin were employed to hydrolyze protein extract from coffee beans. Bioactive peptides were identified by LC-MS/MS analysis coupled with database searching. The potential bioactivities of peptides were predicted by in silico screening, among which five novel peptides may have ACE inhibitory activity. In vitro assay was carried out to determine the ACE inhibitory degree. Two peptides (IIPNEVY, ITPPVMLPP) were obtained with IC50 values of 57.54 and 40.37 μM, respectively. Furthermore, it was found that two inhibitors bound to the receptor protein on similar sites near the S1 active pocket of ACE to form stable enzyme-peptide complexes through molecular docking, and the Lineweaver-Burk plot showed that IIPNEVY was a noncompetitive inhibitor, and ITPPVMLPP was suggested to be a mixed-type inhibitor. Our study demonstrated that two peptides isolated from coffee have potential applications as antihypertensive agents.

Exploring Bioactivities and Peptide Content of Body Mucus from the Lusitanian Toadfish Halobatrachus didactylus

Identifying bioactive molecules from marine organisms is still vastly understudied. Fish remain an untapped source of bioactive molecules, even when considering species whose toxicity to other fish species has been noticed before. We assessed potential applications of crude body mucus of the Lusitanian toadfish (Halobratachus didactylus) and characterized its peptide fraction composition. Mucus samples from three individuals (two wild and one captive) revealed potential antioxidant, antihypertensive, and antimicrobial activities. For antioxidant activity, the best results of 2371 ± 97 µmol Trolox Equivalent/g protein for ORAC and 154 ± 6 µmol Trolox Equivalent/g protein for ABTS were obtained. For antihypertensive activity, the relevant inhibitory activity of ACE resulted in IC50 of 60 ± 7 µg protein/mL. Antimicrobial activity was also identified against the pathogenic bacteria Escherichia coli and Listeria monocytogenes. The peptide profile of the crude body mucus was obtained through size exclusion chromatography, with a conspicuous peak at ca. 800 Da. LC-MS/MS allowed the detection of the most probable peptide sequences of this dominant peptide. This is the first study where the bioactive potential of mucus from the Lusitanian toadfish is demonstrated. Peptides with such properties can be applied in the food and pharmaceutical industries.

Eighteen Novel Bioactive Peptides from Monkfish (Lophius litulon) Swim Bladders: Production, Identification, Antioxidant Activity, and Stability

In the study, papain was chosen from five proteases to hydrolyze proteins of monkfish swim bladders for effectively utilizing monkfish (Lophius litulon) processing byproducts, and the hydrolysis conditions of papain were optimized as hydrolysis temperature of 65 °C, pH 7.5, enzyme dose 2.5% and time 5 h using single-factor and orthogonal experiments. Eighteen peptides were purified from the swim bladder hydrolysate of monkfish by ultrafiltration and gel permeation chromatography methods and identified as YDYD, QDYD, AGPAS, GPGPHGPSGP, GPK, HRE, GRW, ARW, GPTE, DDGGK, IGPAS, AKPAT, YPAGP, DPT, FPGPT, GPGPT, GPT and DPAGP, respectively. Among eighteen peptides, GRW and ARW showed significant DPPH· scavenging activities with EC₅₀ values of 1.053 ± 0.003 and 0.773 ± 0.003 mg/mL, respectively; YDYD, QDYD, GRW, ARW and YPAGP revealed significantly HO· scavenging activities with EC₅₀ values of 0.150 ± 0.060, 0.177 ± 0.035, 0.201 ± 0.013, 0.183 ± 0.0016 and 0.190 ± 0.010 mg/mL, respectively; YDYD, QDYD, ARW, DDGGK and YPAGP have significantly O2-· scavenging capability with EC₅₀ values of 0.126 ± 0.0005, 0.112 ± 0.0028, 0.127 ± 0.0002, 0.128 ± 0.0018 and 0.107 ± 0.0002 mg/mL, respectively; and YDYD, QDYD and YPAGP showed strong ABTS⁺· scavenging ability with EC₅₀ values of 3.197 ± 0.036, 2.337 ± 0.016 and 3.839 ± 0.102 mg/mL, respectively. YDYD, ARW and DDGGK displayed the remarkable ability of lipid peroxidation inhibition and Ferric-reducing antioxidant properties. Moreover, YDYD and ARW can protect Plasmid DNA and HepG2 cells against H₂O₂-induced oxidative stress. Furthermore, eighteen isolated peptides had high stability under temperatures ranging from 25-100 °C; YDYD, QDYD, GRW and ARW were more sensitive to alkali treatment, but DDGGK and YPAGP were more sensitive to acid treatment; and YDYD showed strong stability treated with simulated GI digestion. Therefore, the prepared antioxidant peptides, especially YDYD, QDYD, GRW, ARW, DDGGK and YPAGP from monkfish swim bladders could serve as functional components applied in health-promoting products because of their high-antioxidant functions.

Formation of Oxidative Compounds during Enzymatic Hydrolysis of Byproducts of the Seafood Industry

There is a significant potential to increase the sustainability of the fishing and aquaculture industries through the maximization of the processing of byproducts. Enzymatic hydrolysis provides an opportunity to valorize downstream fish industry byproducts for the production of protein hydrolysates (FPH) as a source of bioactive peptides (BAP) with health benefits. Deteriorative oxidative reactions may occur during the enzymatic hydrolysis of byproducts, influencing the safety or bioactivities of the end product. Lipid oxidation, autolysis mediated by endogenous enzymes in viscera, protein degradation, and formation of low-molecular-weight metabolites are the main reactions that are expected to occur during hydrolysis and need to be controlled. These depend on the freshness, proper handling, and the type of byproducts used. Viscera, frames, trimmings, and heads are the byproducts most available for enzymatic hydrolysis. They differ in their composition, and, thus, require standardization of both the hydrolysis procedures and the testing methods for each source. Hydrolysis conditions (e.g., enzyme type and concentration, temperature, and time) also have a significant role in producing FPH with specific structures, stability, and bioactivity. Protein hydrolysates with good safety and quality should have many applications in foods, nutraceuticals, and pharmaceuticals. This review discusses the oxidative reactions during the enzymatic hydrolysis of byproducts from different fish industry sectors and possible ways to reduce oxidation.

Simultaneous effect of different chromatographic conditions on the chromatographic retention of pentapeptide derivatives (HGRFG and NPNPT)

Introduction: Oligopeptides exhibit great prospects for clinical application and its separation is of great importance in new drug development. Methods: To accurately predict the retention of pentapeptides with analogous structures in chromatography, the retention times of 57 pentapeptide derivatives in seven buffers at three temperatures and four mobile phase compositions were measured via reversed-phase high-performance liquid chromatography. The parameters ( k H A , k A , and p K a ) of the acid-base equilibrium were obtained by fitting the data corresponding to a sigmoidal function. We then studied the dependence of these parameters on the temperature (T), organic modifier composition (φ, methanol volume fraction), and polarity ( P m N parameter). Finally, we proposed two six-parameter models with (1) pH and T and (2) pH and φ or P m N as the independent variables. These models were validated for their prediction capacities by linearly fitting the predicted retention factor k-value and the experimental k-value. Results: The results showed that log k H A and log k A exhibited linear relationships with 1 / T , φ or P m N for all pentapeptides, especially for the acid pentapeptides. In the model of pH and T, the correlation coefficient (R²) of the acid pentapeptides was 0.8603, suggesting a certain prediction capability of chromatographic retention. Moreover, in the model of pH and φ or P m N , the R² values of the acid and neutral pentapeptides were greater than 0.93, and the average root mean squared error was approximately 0.3, indicating that the k-values could be effectively predicted. Discussion: In summary, the two six-parameter models were appropriate to characterize the chromatographic retention of amphoteric compounds, especially the acid or neutral pentapeptides, and could predict the chromatographic retention of pentapeptide compounds.

Anti-inflammatory action of ark shell (Scapharca subcrenata) protein hydrolysate in LPS-stimulated RAW264.7 murine macrophages

Potential anti-inflammatory effects of ark shell (Scapharca subcrenata) protein hydrolysates were investigated. Ark shell protein hydrolysates were prepared using Alcalase® and pepsin and were designated ASAH and ASPH, respectively. The nitric oxide (NO) inhibitory activity of ASAH and ASPH was determined in lipopolysaccharides (LPS)-stimulated RAW264.7 murine macrophages, and the results showed that ASAH inhibited better NO inhibitory activity than ASPH. ASAH suppressed inflammatory mediator, a prostaglandin E2, secretion of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6), and production of reactive oxygen species (ROS) dose dependently. It inhibited the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and simulated heme oxygenase-1 (HO-1) protein expression. However, the pharmacological approach revealed that pretreatment with zinc protoporphyrin ІX (ZnPP), an inhibitor of HO-1, reversed the anti-inflammatory effect of ASAH. Moreover, ASAH upregulated phosphorylation of mitogen-activated protein kinases (MAPKs) including ERK1/2, JNK1/2, and p38 MAPK. To find out the role of MAPKs phosphorylation, MAPKs inhibitors were used, and the results showed that ASAH-mediated HO-1 protein expression and Nrf2 nuclear translocation were abolished. Taken all together, this study revealed that ASAH has a potential anti-inflammatory activity through regulation of the MAPK-dependent HO-1/Nrf2 pathway. PRACTICAL APPLICATIONS: Food-derived marine bioactive peptides, due to their pivotal role in biological activities, are gaining much attention recently. However, the anti-inflammatory activities of ark shell protein hydrolysates still remain to be investigated. This study investigated that ASAH shows potential anti-inflammatory activities through regulation of the MAPK-dependent HO-1/Nrf2 pathway in RAW264.7 murine macrophages. These findings indicated that ASAH may be used as a dietary supplement, functional food, and medicinal drug for the management of inflammation and inflammation-associated diseases.

Bioactive Peptides from Skipjack Tuna Cardiac Arterial Bulbs: Preparation, Identification, Antioxidant Activity, and Stability against Thermal, pH, and Simulated Gastrointestinal Digestion Treatments

Cardiac arterial bulbs of Skipjack tuna (Katsuwonus pelamis) are rich in elastin, and its hydrolysates are high quality raw materials for daily cosmetics. In order to effectively utilizing Skipjack tuna processing byproducts-cardiac arterial bulbs and to prepare peptides with high antioxidant activity, pepsin was selected from six proteases for hydrolyzing proteins, and the best hydrolysis conditions of pepsin were optimized. Using ultrafiltration and chromatographic methods, eleven antioxidant peptides were purified from protein hydrolysate of tuna cardiac arterial bulbs. Four tripeptides (QGD, PKK, GPQ and GLN) were identified as well as seven pentapeptides (GEQSN, GEEGD, YEGGD, GEGER, GEGQR, GPGLM and GDRGD). Three out of them, namely the tripeptide PKK and the pentapeptides YEGGD and GPGLM exhibited the highest radical scavenging activities on 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and superoxide anion assays. They also showed to protect plasmid DNA and HepG2 cells against H₂O₂-induced oxidative stress. Furthermore, they exhibited high stability under temperature ranged from 20-100 °C, pH values ranged from 3-11, and they simulated gastrointestinal digestion for 240 min. These results suggest that the prepared eleven antioxidant peptides from cardiac arterial bulbs, especially the three peptides PKK, YEGGD, and GPGLM, could serve as promising candidates in health-promoting products due to their high antioxidant activity and their stability.

A novel angiotensin-I-converting enzyme inhibitory peptide from oyster: Simulated gastro-intestinal digestion, molecular docking, inhibition kinetics and antihypertensive effects in rats

In this study, a novel peptide, AEYLCEAC with high angiotensin-I-converting enzyme inhibitory (ACEI) activity was screened from oyster (Crassostrea gigas) hydrolysates, which was obtained from simulated gastro-intestinal digestion. Candidate peptides were confirmed to have a higher binding to angiotensin-I-converting enzyme (ACE) than the positive drug phosphoinic tripeptide calculated by Discovery Studio, and AEYLCEAC showed the highest ACE inhibition rate in vitro with a IC50 of 4.287 mM. Lineweaver-Burk plots confirmed that the peptidic inhibitory type of ACE is competitive. The molecular docking showed that ACEI activity of the AEYLCEAC was mainly due to the hydrogen bonding interactions with the active pockets (S1 and S2) of ACE. In vivo, AEYLCEAC effectively reduced diastolic blood pressure (DBP) and Systolic blood pressure (SBP) in hypertensive rats. These results indicate that AEYLCEAC might act as a helpful ingredient in functional foods or pharmaceuticals for the prevention and treatment of hypertension.

Novel angiotensin-converting enzyme inhibitory peptides from tuna byproducts—milts: Preparation, characterization, molecular docking study, and antioxidant function on H2O2-damaged human umbilical vein endothelial cells

To prepare peptides with high angiotensin-converting enzyme (ACE) inhibitory (ACEi) activity, Alcalase was screened from five proteases and employed to prepare protein hydrolysate (TMH) of skipjack tuna (Katsuwonus pelamis) milts. Subsequently, 10 novel ACEi peptides were isolated from the high-ACEi activity TMH and identified as Tyr-Asp-Asp (YDD), Thr-Arg-Glu (TRE), Arg-Asp-Tyr (RDY), Thr-Glu-Arg-Met (TERM), Asp-Arg-Arg-Tyr-Gly (DRRYG), Ile-Cys-Tyr (ICY), Leu-Ser-Phe-Arg (LSFR), Gly-Val-Arg-Phe (GVRF), Lys-Leu-Tyr-Ala-Leu-Phe (KLYALF), and Ile-Tyr-Ser-Pro (IYSP) with molecular weights of 411.35, 404.41, 452.45, 535.60, 665.69, 397.48, 521.61, 477.55, 753.91, and 478.53 Da, respectively. Among them, the IC₅₀ values of ICY, LSFR, and IYSP on ACE were 0.48, 0.59, and 0.76 mg/mL, respectively. The significant ACEi activity of ICY, LSFR, and IYSP with affinities of −7.0, −8.5, and −8.3 kcal/mol mainly attributed to effectively combining with the ACEi active sites through hydrogen bonding, electrostatic force, and hydrophobic interaction. Moreover, ICY, LSFR, and IYSP could positively influence the production of nitric oxide (NO) and endothelin-1 (ET-1) secretion in human umbilical vein endothelial cells (HUVECs) and weaken the adverse impact of norepinephrine (NE) on the production of NO and ET-1. In addition, ICY, LSFR, and IYSP could provide significant protection to HUVECs against H₂O₂ damage by increasing antioxidase levels to decrease the contents of reactive oxide species and malondialdehyde. Therefore, the ACEi peptides of ICY, LSFR, and IYSP are beneficial functional molecules for healthy foods against hypertension and cardiovascular diseases.

Production of Bioactive Peptides from Sea Cucumber and Its Potential Health Benefits: A Comprehensive Review

Bioactive peptides from food have been widely studied due to their potential applications as functional foods and pharmaceuticals. Sea cucumber, a traditional tonic food, is characterized by high protein and low fat, thereby substrates are being studied to release sea cucumber peptides (SCPs). Although recent studies have shown that SCPs have various bioactive functions, there is no literature reviewing the development status of SCPs. In this review, we summarized the production of SCPs, including their purification and identification, then mainly focused on the comprehensive potential health benefits of SCP in vivo and in vitro, and finally discussed the challenge facing the development of SCPs. We found that SCPs have well-documented health benefits due to their antioxidation, anti-diabetes, ACE inhibitory, immunomodulatory, anti-cancer, anti-fatigue, anti-aging, neuroprotection, micromineral-chelating, etc. However, the structure-activity relationships of SCPs and the functional molecular mechanisms underlying their regulation in vivo need further investigation. Research on the safety of SCP and its potential regulation mechanism will contribute to transferring these findings into commercial applications. Hopefully, this review could promote the development and application of SCPs in further investigation and commercialization.

Angiotensin-I-Converting Enzyme Inhibitory Activity of Protein Hydrolysates Generated from the Macroalga Laminaria digitata (Hudson) JV Lamouroux 1813

Seaweeds have a long history of use as both food and medicine, especially in Asian cultures. Moreover, there is growing interest in the use of seaweed ingredients and bioactive compounds in pharmaceutical and nutraceutical products. One ailment that seaweed bioactive compounds may impact is hypertension caused by the enzyme Angiotensin Converting Enzyme 1 (ACE-1; EC 3.4.15.1), found within the Renin-Angiotensin Aldosterone System (RAAS), which causes vasoconstriction of blood vessels, including veins and arteries. The aim of this paper is to generate bioactive peptide containing protein hydrolysates from the brown seaweed Laminaria digitata (Hudson) JV Lamouroux 1813. Proteins were extracted from this seaweed by disrupting the seaweed cell wall using a combination of carbohydrases and proteolytic enzymes. Bioactive peptide containing permeates were generated from L. digitata protein hydrolysates, and both hydrolysates and permeates were screened for their ability to inhibit the enzyme ACE-1. The protein content of the permeate fractions was found to be 23.87% compared to the untreated seaweed, which contained 15.08% protein using LECO analysis. Hydrolysis and filtration resulted in a “white” protein powder, and the protein content of this powder increased by 9% compared to the whole seaweed. The total amino acid (TAA) content of the L. digitata protein permeate was 53.65 g/100 g of the sample, and contains over 32% essential amino acids (EAA). Furthermore, the L. digitata permeate was found to inhibit the ACE-1 enzyme by 75% when compared to the commercial drug Captopril© when assayed at a concentration of 1 mg/mL. The inhibition of ACE-1 (the IC₅₀ value) of 590 µg/mL for the L. digitata permeate compares well with Captopril©, which had 100% inhibition of ACE-1, with an IC₅₀ value of 500 µg/mL. This study indicates that there is potential to develop protein powders with ACE-1 inhibitory bioactivities from the brown seaweed L. digitata using enzymatic hydrolysis as a cell disruption and protein extraction/hydrolysate generation procedure.

Preparation, Characterization, and Cytoprotective Effects on HUVECs of Fourteen Novel Angiotensin-I-Converting Enzyme Inhibitory Peptides From Protein Hydrolysate of Tuna Processing By-Products

To effectively utilize skipjack tuna (Katsuwonus pelamis) processing by-products to prepare peptides with high angiotensin-I-converting enzyme (ACE) inhibitory (ACEi) activity, Neutrase was selected from five kinds of protease for hydrolyzing skipjack tuna dark muscle, and its best hydrolysis conditions were optimized as enzyme dose of 1.6%, pH 6.7, and temperature of 50°C using single factor and response surface experiments. Subsequently, 14 novel ACEi peptides were prepared from the high ACEi protein hydrolysate and identified as TE, AG, MWN, MEKS, VK, MQR, MKKS, VKRT, IPK, YNY, LPRS, FEK, IRR, and WERGE. MWN, MEKS, MKKS, and LPRS displayed significantly ACEi activity with IC₅₀ values of 0.328 ± 0.035, 0.527 ± 0.030, 0.269 ± 0.006, and 0.495 ± 0.024 mg/mL, respectively. Furthermore, LPRS showed the highest increasing ability on nitric oxide (NO) production among four ACEi peptides combining the direct increase and reversing the negative influence of norepinephrine (NE), and MKKS showed the highest ability on directly decreasing and reversing the side effects of NE on the secretion level of endothelin-1 (ET-1) among four ACEi peptides. These findings demonstrate that seafood by-product proteins are potential ACEi peptide sources and prepared ACEi peptides from skipjack tuna dark muscle, which are beneficial components for functional food against hypertension and cardiovascular diseases.

Preparation, Identification, Molecular Docking Study and Protective Function on HUVECs of Novel ACE Inhibitory Peptides from Protein Hydrolysate of Skipjack Tuna Muscle

To prepare bioactive peptides with high angiotensin-I-converting enzyme (ACE)-inhibitory (ACEi) activity, Alcalase was selected from five kinds of protease for hydrolyzing Skipjack tuna (Katsuwonus pelamis) muscle, and its best hydrolysis conditions were optimized using single factor and response surface experiments. Then, the high ACEi protein hydrolysate (TMPH) of skipjack tuna muscle was prepared using Alcalase under the optimum conditions of enzyme dose 2.3%, enzymolysis temperature 56.2 °C, and pH 9.4, and its ACEi activity reached 72.71% at 1.0 mg/mL. Subsequently, six novel ACEi peptides were prepared from TMPH using ultrafiltration and chromatography methods and were identified as Ser-Pro (SP), Val-Asp-Arg-Tyr-Phe (VDRYF), Val-His-Gly-Val-Val (VHGVV), Tyr-Glu (YE), Phe-Glu-Met (FEM), and Phe-Trp-Arg-Val (FWRV), with molecular weights of 202.3, 698.9, 509.7, 310.4, 425.6, and 606.8 Da, respectively. SP and VDRYF displayed noticeable ACEi activity, with IC₅₀ values of 0.06 ± 0.01 and 0.28 ± 0.03 mg/mL, respectively. Molecular docking analysis illustrated that the high ACEi activity of SP and VDRYF was attributed to effective interaction with the active sites/pockets of ACE by hydrogen bonding, electrostatic force, and hydrophobic interaction. Furthermore, SP and VDRYF could significantly up-regulate nitric oxide (NO) production and down-regulate endothelin-1 (ET-1) secretion in HUVECs after 24 h treatment, but also abolish the negative effect of 0.5 μM norepinephrine (NE) on the generation of NO and ET-1. Therefore, ACEi peptides derived from skipjack tuna (K. pelamis) muscle, especially SP and VDRYF, are beneficial components for functional food against hypertension and cardiovascular diseases.

Macroalgal Proteins: A Review

Population growth is the driving change in the search for new, alternative sources of protein. Macroalgae (otherwise known as seaweeds) do not compete with other food sources for space and resources as they can be sustainably cultivated without the need for arable land. Macroalgae are significantly rich in protein and amino acid content compared to other plant-derived proteins. Herein, physical and chemical protein extraction methods as well as novel techniques including enzyme hydrolysis, microwave-assisted extraction and ultrasound sonication are discussed as strategies for protein extraction with this resource. The generation of high-value, economically important ingredients such as bioactive peptides is explored as well as the application of macroalgal proteins in human foods and animal feed. These bioactive peptides that have been shown to inhibit enzymes such as renin, angiotensin-I-converting enzyme (ACE-1), cyclooxygenases (COX), α-amylase and α-glucosidase associated with hypertensive, diabetic, and inflammation-related activities are explored. This paper discusses the significant uses of seaweeds, which range from utilising their anthelmintic and anti-methane properties in feed additives, to food techno-functional ingredients in the formulation of human foods such as ice creams, to utilising their health beneficial ingredients to reduce high blood pressure and prevent inflammation. This information was collated following a review of 206 publications on the use of seaweeds as foods and feeds and processing methods to extract seaweed proteins.

Seventeen novel angiotensin converting enzyme (ACE) inhibitory peptides from protein hydrolysate of Mytilus edulis: Isolation, identification, molecular docking study, and protective function on HUVECs

In the study, seventeen angiotensin converting enzyme (ACE) inhibitory peptides were isolated from protein hydrolysate of blue mussel (Mytilus edulis) and identified as MFR, MFV, FV, KP, QP, QVK, IK,...

Bioactive Properties of Peptides and Polysaccharides Derived from Peanut Worms: A Review

Peanut worms (Sipunculids) are unsegmented marine worms that usually inhabit shallow waters. Peanut worms are good source of bioactive compounds including peptides and polysaccharides. Many recent studies have investigated the bioactive properties of peptides and polysaccharides derived from peanut worms in order to enhance their applications in food and pharmaceutical industries. The peptides and polysaccharides isolated from peanut worms have been reported to possess anti-hypertensive, anti-oxidant, immunomodulatory, anti-inflammatory, anti-cancer, anti-hypoxia and wound healing activities through the modulation of various molecular mechanisms. Most researchers used in vitro, cell culture and animal models for the determination of bioactivities of peanut worm derived compounds. However, studies in humans have not been performed considerably. Therefore, it is important to conduct more human studies for better utilization of marine bioactive compounds (peptides and polysaccharides) derived from peanut worms. This review mainly focuses on the bioactive properties of peptides and polysaccharides of peanut worms and their molecular mechanisms.

A Novel Angiotensin-I-Converting Enzyme (ACE) Inhibitory Peptide from Takifugu flavidus

Alcalase, neutral protease, and pepsin were used to hydrolyze the skin of Takifugu flavidus. The T. flavidus hydrolysates (TFHs) with the maximum degree of hydrolysis (DH) and angiotensin-I-converting enzyme (ACE)-inhibitory activity were selected and then ultra-filtered to obtain fractions with components of different molecular weights (MWs) (<1, 1-3, 3-10, 10-50, and >50 kDa). The components with MWs < 1 kDa showed the strongest ACE-inhibitory activity with a half-maximal inhibitory concentration (IC50) of 0.58 mg/mL. Purification and identification using semi-preparative liquid chromatography, Sephadex G-15 gel chromatography, RP-HPLC, and LC-MS/MS yielded one new potential ACE-inhibitory peptide, PPLLFAAL (non-competitive suppression mode; IC50 of 28 μmmol·L-1). Molecular docking and molecular dynamics simulations indicated that the peptides should bind well to ACE and interact with amino acid residues and the zinc ion at the ACE active site. Furthermore, a short-term assay of antihypertensive activity in spontaneously hypertensive rats (SHRs) revealed that PPLLFAAL could significantly decrease the systolic blood pressure (SBP) and diastolic blood pressure (DBP) of SHRs after intravenous administration. These results suggested that PPLLFAAL may have potential applications in functional foods or pharmaceuticals as an antihypertensive agent.

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.

Food Matrices Affect the Peptides Produced during the Digestion of Arthrospira platensis-Based Functional Aliments

Arthrospira platensis (Spirulina) has been credited with multiple beneficial effects, many of which are attributed to bioactive peptides produced during the gastrointestinal digestion of this micro-alga. Many Spirulina-based nutraceuticals have been produced, and numerous functional foods enriched with Spirulina are available on the market. These are subjected to checks aimed at verifying the amount of algae actually present, but few studies relating to the bioavailability of the bioactive compounds in these products have been carried out. However, such investigations could be very important to elucidate the possible critical effects exerted by food matrices on protein digestion and bioactive peptide production. Here, in order to assess the suitability of Spirulina-enriched foods as a source of potentially bioactive peptides, a simulated digestion protocol was used in combination with mass spectrometry quantitative analysis to analyze functionalized pasta and sorbets. In the case of the pasta enriched with Spirulina, the production of peptides was quite similar to that of the Spirulina powder. On the other hand, the type of fruit present in the food matrix influenced the digestion of Spirulina inside the sorbets. In particular, the high concentration of protease inhibitors in kiwifruit drastically reduced the production of peptides from Spirulina in kiwi sorbet.

Advancement and prospects of production, transport, functional activity and structure-activity relationship of food-derived angiotensin converting enzyme (ACE) inhibitory peptides

Food-derived antihypertensive peptides have attracted increasing attention in functional foods for health promotion, due to their high biological activity, low toxicity and easy metabolism in the human body. Angiotensin converting enzyme (ACE) is a key enzyme that causes the increase in blood pressure in mammals. However, few reviews have summarized the current understanding of ACE inhibitory peptides and their knowledge gaps. This paper focuses on the food origins and production methods of ACE inhibitory peptides. Compared with conventional methods, the advanced technologies and emerging bioinformatics approaches have recently been applied for efficient and targeted release of ACE inhibitory peptides from food proteins. Furthermore, the transport and underlying mechanisms of ACE inhibitory peptides are emphatically described. Molecular modeling and the Michaelis-Menten equation can provide information on how ACE inhibitors function. Finally, we discuss the structure-activity relationships and other bio-functional properties of ACE inhibitory peptides. Molecular weight, hydrophobic amino acid residues, charge, amino acid composition and sequence (especially at the C-terminal and N-terminal) have a significant influence on ACE inhibitory activity. Some studies are required to increase productivity, improve bioavailability of peptides, evaluate their bio-accessibility and efficiency on reducing blood pressure to provide a reference for the development and application of health products and auxiliary treatment drugs.

Seaweed Components as Potential Modulators of the Gut Microbiota

Macroalgae, or seaweeds, are a rich source of components which may exert beneficial effects on the mammalian gut microbiota through the enhancement of bacterial diversity and abundance. An imbalance of gut bacteria has been linked to the development of disorders such as inflammatory bowel disease, immunodeficiency, hypertension, type-2-diabetes, obesity, and cancer. This review outlines current knowledge from in vitro and in vivo studies concerning the potential therapeutic application of seaweed-derived polysaccharides, polyphenols and peptides to modulate the gut microbiota through diet. Polysaccharides such as fucoidan, laminarin, alginate, ulvan and porphyran are unique to seaweeds. Several studies have shown their potential to act as prebiotics and to positively modulate the gut microbiota. Prebiotics enhance bacterial populations and often their production of short chain fatty acids, which are the energy source for gastrointestinal epithelial cells, provide protection against pathogens, influence immunomodulation, and induce apoptosis of colon cancer cells. The oral bioaccessibility and bioavailability of seaweed components is also discussed, including the advantages and limitations of static and dynamic in vitro gastrointestinal models versus ex vivo and in vivo methods. Seaweed bioactives show potential for use in prevention and, in some instances, treatment of human disease. However, it is also necessary to confirm these potential, therapeutic effects in large-scale clinical trials. Where possible, we have cited information concerning these trials.

Cytoprotective Effects of Fish Protein Hydrolysates against H2O2-Induced Oxidative Stress and Mycotoxins in Caco-2/TC7 Cells

Many studies report the potent antioxidant capacity for fish protein hydrolysates, including radical scavenging activity and inhibition ability on lipid peroxidation (LPO). In this study, the in vitro cytotoxicity of protein hydrolysates from different salmon, mackerel, and herring side streams fractions was evaluated in the concentration range from 1 to 1:32 dilution, using cloned human colon adenocarcinoma cells TC7 (Caco-2/TC7) by MTT and PT assays. The protein hydrolysates' antioxidant capacity and oxidative stress effects were evaluated by LPO and reactive oxygen species (ROS) generation, respectively. The antioxidant capacity for pure and bioavailable hydrolysate fraction was also evaluated and compared. Additionally, mycotoxin levels were determined in the fish protein hydrolysates, and their cytoprotective effect against T-2 toxin was evaluated. Both hydrolysates and their bioavailable fraction induced similar cell viability rates. The highest cytoprotective effect was obtained for the salmon viscera protein hydrolysate (HSV), which increased the cell viability by 51.2%. ROS accumulation induced by H₂O₂ and LPO was suppressed by all pure hydrolysates. The cytoprotective effect of hydrolysates was observed against T-2. Moreover, the different fish fraction protein hydrolysates contain variable nutrients and unique bioactive peptide composition showing variable bioactivity, which could be a useful tool in developing dietary supplements with different target functional properties.

Purification and characterization of a novel angiotensin I-converting enzyme-inhibitory peptide derived from Alaska pollack skins

Hydrolysates containing angiotensin I-converting enzyme (ACE)-inhibitory peptide were prepared from protein of Alaska pollack skins using alcalase and trypsin. The protein hydrolysate was separated by ultrafiltration, Sephadex G-25 gel filtration chromatography and reversed phase high-performance liquid chromatography (HPLC), from which a novel purified peptide was obtained. Both random coil structure and β-sheet in the purified peptide were revealed in Fourier transform infrared spectrum. The amino sequence of the purified peptide was identified as GPLGVP, VLYPVK, VFLENVLR, and FEEF by HPLC-Q-TOF-MS (HPLC-quadrupole time-of-flight mass spectrometry). The peptide GPLGVP whose molecular weight was 538.31 Da showed the highest ACE inhibitory activity (IC₅₀  = 105.8 µM). The purified peptide featured a noncompetitive inhibition kinetic mechanism was shown in the Lineweaver-Burk plots and was susceptible to enzymes as indicated in the studies on stability of gastrointestinal proteases. Moreover, the peptide GPLGVP can combine ACE catalytic pocket through hydrogen bonds and other forces with high binding power as disclosed in molecular docking simulation, which provides the inhibitory effect of GPLGVP on ACE.

Recent developments on production, purification and biological activity of marine peptides

Marine peptides are one of the richest sources of structurally diverse bioactive compounds and a considerable attention has been drawn towards their production and bioactivity. However, there is a paucity in consolidation of emerging trends encompassing both production techniques and biological application. Herein, we intend to review the recent advancements on different production, purification and identification technologies used for marine peptides along with presenting their potential health benefits. Bibliometric analysis revealed a growing number of scientific publications on marine peptides (268 documents per year) with both Asia (37.2%) and Europe (33.1%) being the major contributors. Extraction and purification by ultrafiltration and enzymatic hydrolysis, followed by identification by chromatographic techniques coupled with an appropriate detector could yield a high content of peptides with improved bioactivity. Moreover, the multifunctional health benefits exerted by marine peptides including anti-microbial, antioxidant, anti-hypertension, anti-diabetes and anti-cancer along with their structure-activity relationship were presented. The future perspective on marine peptide research should focus on finding improved separation and purification technologies with enhanced selectivity and resolution for obtaining more novel peptides with high yield and low cost. In addition, by employing encapsulation strategies such as nanoemulsion and nanoliposome, oral bioavailability and bioactivity of peptides can be greatly enhanced. Also, the potential health benefits that are demonstrated by in vitro and in vivo models should be validated by conducting human clinical trials for a technology transfer from bench to bedside.

Antihypertensive Potential of Plant Foods: Research Progress and Prospect of Plant-Derived Angiotensin-Converting Enzyme Inhibition Compounds

Global health concerns are clearly evidenced by cardiovascular disease, kidney damage, and heart attacks. Antihypertensive synthetic drugs, including angiotensin-converting enzyme (ACE) inhibitors, effectively control hypertension but with unpleasant side effects. In recent decades, studies on the role of food-derived compounds have provided a positive contribution to ACE regulation. Here, the research progress of plant food-derived phenolic compounds as ACE inhibitors is reviewed. A survey of bioactive compounds of plant food is presented to broaden the source scope of natural ACE inhibitors. A consecutive understanding of plant-derived ACE inhibitors classification, inhibition mechanism, structure-activity relationship, and bioavailability are scientifically organized. The emerging evidence highlights areas that need further research, including those related to molecular structure, bioaccessibility, and interactions with gut microflora. Future research on such topics may encourage basic research and clinic application to exploit these plant food constituents as novel ACE inhibitors.

Extraction optimization and screening of angiotensin-converting enzyme inhibitory peptides from Channa striatus through bioaffinity ultrafiltration coupled with LC-Orbitrap-MS/MS and molecular docking

Channa striatus is high-protein food with many health functions. This study aimed to prepare, screen and identify the angiotensin-converting enzyme inhibition peptides (ACEIPs) from C. striatus hydrolysates by response surface methodology and bioaffinity ultrafiltration coupled with LC-Orbitrap-MS/MS and molecular docking. The optimal conditions for preparing ACEIPs were hydrolysis temperature 55 °C, hydrolysis time 3 h, pH 9, solid-liquid ratio 1:20 g/mL, and enzyme addition 5%, the ACE inhibition and molecular weight distribution of obtained hydrolysate was 54.35% and 8770-160 Da, respectively. Seven novel ACEIPs were screened through the established high-throughput screening approach, among which, EYFR and LPGPGP showed the strongest ACE inhibition with the IC₅₀ value of 179.2 and 186.3 μM, respectively (P > 0.05). Molecular docking revealed that three and ten hydrogen bonds were formed between ACE and LPGPGP and EYFR, respectively, S1 and S2 were the major active pockets, but the major driving forces varied.

Accurate prediction for adsorption rate of peptides with high ACE-inhibitory activity from sericin hydrolysate on thiophene hypercross-linked polymer using CoMSIA in 3D-QSAR model

Efficient screening of angiotensin converting enzyme inhibitory (ACE-I) peptides from agricultural or edible sources attract increasing attention. However, their purification process from the complex natural system is still semi-empirical or even uncontrollable, which has seriously reduced their screening efficiency. Herein, inspired by the prediction of ACE-I activity, 3D-QSAR was proposed to predict the adsorption performance of peptides from sericin hydrolysate (SH) having high ACE-I activity on porous hypercross-linked polymers according to their molecular structures. Thiophene hypercross-linked polymer (T-HCP) possessing better screening capacity for ACE-I peptides was chosen as our research object in this work. The sequence and relative adsorption rate of 101 peptides in SH were analyzed by LC-MS and was used as a database to construct the relationship of peptide's chemical structure and adsorption performance on T-HCP by Comparative molecular similarity indices analysis (CoMSIA) from 3D-QSAR. Optimum CoMSIA revealed that enhanced interaction of hydrophobicity and H-bond between T-HCP and the peptide was conducive to increase the adsorption performance of di- to hexa- peptides. Based on these relationships, the adsorption capability of 24 designed peptides with distinguished hydrophobic and H-bond fields was predicted on T-HCP by using optimum CoMSIA and the results of half of these were verified, which showed high consistency with their predicted adsorption rate. Interestingly, these peptides having higher adsorption capacities on T-HCP also possessed higher ACE-I activity. This can be attributed to the high concentration of aromatic surface with π-π interaction and weak-polar CSC group with H-bond interaction on T-HCP material, which is ideal for the selective adsorption of peptides with higher ACE-I activity from SH. This study provides important theoretical guidance for the industrial screening of bio-functional peptides from complex protein mixtures.

Dual-enzyme hydrolysis for preparation of ACE-inhibitory peptides from sesame seed protein: Optimization, separation, and identification

To prepare and identify ACE-inhibitory peptides originated from sesame seed protein, peptides with strong ACE-inhibitory activities were obtained via the optimization of protease and hydrolysis conditions, and these peptides were purified and identified by membrane separation, gel filtration, and liquid chromatography-mass spectrometry. Results showed that the dual-enzyme comprised alcalase and trypsin with the enzyme activity ratio of 3:7 was suitable to produce ACE-inhibitory peptides. The highest ACE-inhibitory activity of 98.10 ± 0.26% was obtained at the following parameters, pH 8.35, E/S ratio of 6,145 U/g, and hydrolysis time of 4.4 hr. ISGAQPSLR and VVISAPSK ranked the first and second ACE-inhibitory activity among 15 identified ACE-inhibitory peptides. Both peptides influenced ACE via binding with the S1 pocket, S2 pocket, and Zn²⁺ ion. ISGAQPSLR even impacted the S1' pocket. ISGAQPSLR and VVISAPSK acted as a competitive and noncompetitive inhibitor, respectively. ACE-inhibitory peptides derivated from sesame seed protein have potential applications in functional food. PRACTICAL APPLICATIONS: Although sesame seed protein is proven as the precursor of ACE-inhibitory peptide, preparing ACE-inhibitory peptide from sesame seed protein is still suffering from insufficient information on hydrolysis condition and the peptide sequence. Therefore, the performance of the typical protease on preparing ACE-inhibitory peptide from sesame seed protein has been evaluated, the effect of the amino acid composition of sesame seed protein and cleavage specificity of protease on the generation of ACE-inhibitory peptide has been investigated, hydrolysis conditions have been optimized, the peptide sequence has been identified to illuminate the effect of sesame seed protein fraction on the formation of ACE-inhibitory peptide and discuss the structural characteristics. ACE-inhibitory peptides originating from sesame seed protein could apply in functional food. It is promising for dual-enzyme hydrolysis to utilize in preparation of high-value bioactive peptides.

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.