ACE-inhibitory Peptides Research Articles

Identification and characterization of a novel tetrapeptide from enzymatic hydrolysates of Baijiu byproduct

In order to prepare angiotensin I-converting enzyme (ACE) inhibitory peptides, distilled spent grains of Chinese strong-flavor Baijiu were hydrolyzed by alcalase followed by papain under optimized conditions. A superior ACE inhibitory peptide was separated and purified by ultrafiltration and high-performance liquid chromatography (HPLC), and its amino acid sequence was further identified as Gln-Gly-Val-Pro (QGVP) by electrospray mass spectrometry (ESI-MS). QGVP formed 6 hydrogen bonds with the active site of ACE, which is responsible for reducing α-helix structure content of ACE causing subsequent inactivation. Moreover, it showed no significant cytotoxicity toward human umbilical vein endothelial cells (HUVECs), and significantly induced phosphorylation of endothelial nitric oxide synthase (p-eNOS) and decreased endothelin 1 (END1) expression in angiotensin I (Ang I)-treated HUVECs, demonstrating the potential antihypertensive effect. The peptide QGVP hydrolyzed from distilled spent grain proteins of Chinese strong-flavor Baijiu was expected to be used as a food ingredient to prevent or co-treat hypertension with other chemical drugs.

ACE-inhibitory peptide from rohu fish waste: Optimisation of ultrasound and microwave assisted enzymatic extraction using response surface methodology

Anti-hypertensive [angiotensin-I converting cnzyme (ACE) inhibitory (ACEi) peptides are enzymatically extracted from biological material. The high cost of enzymes, low peptide yield and long hydrolysis time in enzymatic extraction paved the way for alternative ultrasound assisted enzymatic extraction (UAEE) and microwave-assisted enzymatic extraction (MAEE). In this study, rohu (Labeo rohita) fish wastes were homogenised and treated with ultrasound (40 kHz) and microwave (2450 MHz) before enzymatic hydrolysis using optimised concentration of alcalase® for the extraction of ACEi. The UAEE (sonication temperature: 30-70; optimum: 57.88ºC and time: 10-50; optimum: 63.4 min) and MAEE (microwave power: 180-900, optimum: 335.23 W and time 5-25, optimum: 15 min) were studied for their effect on degree of hydrolysis (DH), ACE inhibition (ACEi) and peptide yield (PY). The efficiency obtained by UAEE (5%) was higher than MAEE (4%) in terms of ACEi. In contrast, MAEE showed higher efficiency with respect to DH and PY (7 and 6.5 %, respectively) than UAEE (2.5 and 4%, respectively). The study indicated that UAEE and MAEE are efficient methods for extraction of ACE-inhibitory peptides from rohu fish waste. However, UAEE peptides shows better ACEi than MAEE. Keywords: ACE-inhibitory peptide, Alcalase, Degree of hydrolysis, Enzymatic extraction, Peptide yield, Rohu processingwaste

Insights into in vitro digestion properties and peptide profiling of Chinese rubing PDO cheese prepared using different acidification technology

Rubing cheese is a traditional Chinese Protected Designation of Origin (PDO) cheese consumed for more than six hundred years, but to date, the digestion properties and peptide profiling during simulated gastrointestinal digestion are still uncertain. This study aimed to investigate the effects of traditional direct acidification technology (TRB) and fermentation acidification technology on digestion properties and peptide profiling of rubing cheese (FRB) proteins after simulated gastrointestinal digestion by protein digestomics, coupled with bioinformatic in silico analyses to identify potential bioactive peptides. The results demonstrated that FRB could significantly improve the in vitro digestibility, protein degradation, and polypeptide content than TRB (P ＜ 0.05). Furthermore, a total of 369 and 332 peptides were identified in FRB- and TRB-pancreatic digests, respectively, using LC-MS/MS. FRB could release more low molecular weight peptides of 400–1200 Da from α-casein and β-casein after digestion. These low peptides included 16 reported potential ACEIPs (angiotensin I-converting enzyme inhibitory peptides), 11 dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides, and 6 antioxidant peptides, while TRB contained more than the reported potential antimicrobial peptides (10). In vitro activity determination showed that FRB had significantly higher ACEI, α-glucosidase inhibitory, and antioxidant activities than TRB during the entire digestion time (P ＜ 0.05), which was correlated to the reported potential bioactive peptides released during the digestion of FRB. Our study is the most comprehensive protein digestomic analysis of Chinese rubing cheese to date and provides a new positive outlook on rubing cheese consumption.

Purification and Identification of a Novel Angiotensin Converting Enzyme Inhibitory Peptide from the Enzymatic Hydrolysate of Lepidotrigla microptera.

In this study, Lepidotrigla microptera were hydrolyzed with four different proteolytic enzymes (Papain, neutrase, flavourzyme, and alcalase), and their distribution of molecular weights and ACE-inhibitory activity were tested. The alcalase hydrolysates showed the maximum ACE-inhibitory activity. A novel ACE-inhibitory peptide was isolated and purified from Lepidotrigla microptera protein hydrolysate (LMPH) using ultrafiltration, gel filtration chromatography, and preparative high performance liquid chromatography (prep-HPLC). The amino acid sequence of the purified peptide was identified as Phe-Leu-Thr-Ala-Gly-Leu-Leu-Asp (DLTAGLLE), and the IC50 value was 0.13 mg/mL. The ACE-inhibitory activity of DLTAGLLE was stable across a range of temperatures (<100 °C) and pH values (3.0–11.0) and retained after gastrointestinal digestion. DLTAGLLE was further identified as a noncompetitive inhibitor by Lineweaver–Burk plot. The molecular docking simulation showed that DLTAGLLE showed a high binding affinity with ACE sites by seven short hydrogen bonds. As the first reported antihypertensive peptide extracted from alcalase hydrolysate of Lepidotrigla microptera, DLTAGLLE has the potential to develop functional food or novel ACE-inhibitor drugs.

Interaction mechanism of three egg protein derived ACE inhibitory tri-peptides and DPPC membrane using FS, FTIR, and DSC studies.

Understanding the interaction of food derived angiotensin converting enzyme (ACE) inhibitory peptides and intestinal epithelial cell membrane may help to improve their absorption. This research aimed to study the molecular interaction of ACE inhibitory tri-peptides ADF, FGR, and MIR with DPPC membrane during absorption process. The DPPC liposome was prepared and characterized, then used as a model membrane. The permeability of tri-peptides across the membrane was investigated using Fluorescence spectroscopy. The effect of tri-peptides on the structure and dynamics of DPPC bilayers was determined using Fourier transform infrared spectroscopy. The effect of tri-peptides on the phase transition temperature in the DPPC membrane was also analyzed using Differential scanning calorimetry. The results showed that ACE inhibitory tri-peptides ADF, FGR, and MIR can penetrate into both the membrane-water interface and hydrophobic region of DPPC bilayer, and the tri-peptide FGR have higher permeability across the membrane.

A Review on Factors and Processing Methods Affecting Antihypertensive Properties of Legumes, and Antihypertensive Properties of Selected Legumes

Hypertension is one of the major risk factors which leads to cardiovascular diseases, and the typical treatment for hypertension is drug therapy. However, as there are side effects to drug therapy, there has been an increase in research on legume proteins as biopeptides have shown antihypertensive effects. Many species of legumes have been cultivated for consumption as they are a good source of protein, carbohydrates, minerals, vitamins, and dietary fiber. Bioactive compounds of legumes potentially improve factors that affect antihypertensive properties, such as angiotensin-converting enzyme (ACE) inhibition activity, renin inhibition activity, and γ-aminobutyric acid (GABA) production. The processing method of enzymatic hydrolysis can improve ACE inhibition activity, as can be seen with horse gram, pigeon pea, and lentil hydrolysates containing potent ACE inhibitory peptides of Thr-Val-Gly-Met-Thr-Ala-Lys-Phe, Val-Val-Ser-Leu-Ser-Ile-Pro-Arg, and Asn-Ser-Leu-Thr-Leu-Pro-Ile-Leu-Arg-Tyr-Leu, while pigeon pea and kidney bean hydrolysates have shown good renin inhibition activity. Fermentation can also be used to process legumes as potent ACE inhibitory peptide Val-Val-Ser-Leu-Ser-Ile-Pro-Arg was identified from fermented pigeon pea, while kidney beans and lentils demonstrated good GABA production through natural fermentation and fermentation with microbial cultures. The germination processing method could also help improve ACE inhibition activity as horse gram has shown good inhibition activity. In vivo study of pigeon pea, kidney bean, and lentils showed potential antihypertensive properties as a significant lowering of systolic blood pressure of test subject was observed. Research done on the structure and function of antihypertensive properties of legumes can help in the development of functional food products which will be beneficial to human health.

Development and sensory test of a dairy product with ACE inhibitory and antioxidant peptides produced at a pilot plant scale

A scale-up process was carried out to obtain potent bioactive peptides from whey protein through a simple hydrolysis process. The scale-up was satisfactory, with results similar to those obtained at lab scale: a fraction of peptides < 1 kDa with ACE inhibitory activity of 18.44 ± 2.47 μg/mL, a DPPH value of 69.40 ± 0.44%, and an ORAC value of 3.37 ± 0.03 μmol TE/mg protein. The peptide sequences responsible for the ACE inhibitory activity were also similar to those identified at lab scale: PM, LL, LF, HFKG and PT. The hydrolysate was used as a functional ingredient in a low-fat yoghurt. The consumer sensory taste panel found no significant difference (p > 0.05) between the bitterness of the control and the functional yoghurt, and about 50% of consumers would buy it. The hydrolysate maintained its bioactivities for 4 months at −20 °C (after thawing and pasteurisation), and for 1 week in yoghurt at 4 °C.

Proteins from Tenebrio molitor: An interesting functional ingredient and a source of ACE inhibitory peptides

The angiotensin-converting enzyme (ACE) inhibitory potential of the main protein fractions from Tenebrio molitor larvae (TML) was examined to evaluate their use as a novel antihypertensive functional food. Both fractions contained YAN tripeptide, previously reported as responsible for ACE inhibition. Although YAN has been synthesized and was used as a standard for LC-MS/MS quantification and IC50 against ACE was determined, low yields of YAN from TML did not explain adequately the activity of the whole protein fraction. LC-HRMS/MS investigation led to the identification of other three peptides, which were evaluated in silico, synthesized and tested against ACE. Among them, tetrapeptide NIKY showed the most promising activity (52 µM), highlighting once more the potential of TML and paving the way for exploitation in novel foods.

In vitro gastrointestinal digestion study and identification of novel angiotensin i-converting enzyme inhibitory peptide from broccoli (brassica oleracea)

Due to the side effects of synthetic ACE inhibitors like captopril used for the treatment of hypertension, ACE inhibitory peptides derived from natural sources have attracted increasing attention in recent years. The aim of this work was to screen the vegetable with the highest angiotensin I-converting enzyme (ACE) inhibitory activity from 50 kinds of vegetables by using three different extraction methods, and to purify and identify the novel peptides from broccoli protein hydrolysates and evaluated the ACE inhibitory activity in vitro. Through centrifugation, ultrafltration, gel chromatography and high performance liquid chromatography (HPLC), the fraction BHs-IV-I-IV of the enzyme hydrolysate of broccoli with 100% ACE inhibitory activity was obtained. The novel ACE inhibitory peptide (KSVLLKF, KF-7) was identifed from fraction BHs-IV-I-IV by ultra-performance liquid chromatographytandem mass spectrometry (UPLC-MS/MS). ACE inhibition rate of 0.05 mg of KF-7 reached 42.86%, whereas 12.48 mg of pepsin hydrolysate of broccoli crude extract only exhibited 55.29% of ACE inhibition rate, indicating the low content of KF-7 in the protein hydrolysates of broccoli. These results suggested that KF-7 has a potential application in functional foods/pharmaceutical agents against hypertension and protein from broccoli may constitute a potential antihypertensive peptide source.

Angiotensin‐converting enzyme (ACE) inhibitory peptides from fermented sausages inoculated with Lactobacillus plantarum CD101 and Staphylococcus simulans NJ201

AbstractNatural ACE inhibitory peptides derived from food are considered to be an effective supplement for lowering blood pressure. This study investigated the effects of Lactobacillus plantarum CD101 and Staphylococcus simulans NJ201 on proteolysis and the sequence composition of ACE inhibitory peptides in fermented sausages. The ACE inhibitory activity of the inoculated group reached the maximum values on day 35 during the production of fermented sausages. A more positive effect in the hydrolysis of the sarcoplasmic and myofibrillar protein was observed in the inoculated group through sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS‐PAGE). The free amino acid content of the inoculated group was 865.21 ± 12.55 mg/100 g, which was significantly higher (P &lt; 0.05) than that of the control group. The molecular weight distribution showed a significant increase (P &lt; 0.05) in peptides with a molecular weight less than 1 kDa in the inoculated group. A total of thirty‐four peptides with high hydrophobicity were identified by liquid chromatograph‐mass spectrometer/mass spectrometer (LC–MS/MS). Furthermore, the peptides were isolated and purified using gel filtration chromatography (GFC) and reversed‐phased high‐performance liquid chromatography (RP‐HPLC). Eleven novel peptides were identified by Nano‐LC‐ESI‐MS/MS, in which VALSLSRP with X‐Pro structure exhibited the highest ACE inhibition rate (75.36 ± 2.45%). These results indicated that mixed starters are conducive to protein degradation and the formation of peptides with high ACE inhibitory activity, especially peptides less than 1 kDa, and could be used as a functional material for antihypertensive drugs.

Characterization of ACE inhibitory peptide from Cassia tora L. globulin fraction and its antihypertensive activity in SHR

Characterization of ACE inhibitory peptide from Cassia tora L. globulin fraction and its antihypertensive activity in SHR

Exploration of ACE-Inhibiting Peptides Encrypted in Artemisia annua Using In Silico Approach.

The renin-angiotensin system (RAS) is involved in body fluid regulation, but one of its enzymes, angiotensin-converting enzyme (ACE), indirectly causes hypertension by constricting blood vessels. Autoimmune illness is linked to the increased risk of hypertension and cardiovascular disease. In this study, ACE-inhibiting peptides were studied from Artemisia annua proteins. In silico hydrolysis of proteins was performed by BIOPEP-UWM using proteolytic enzymes from plant, microbial, and digestive sources. The physicochemical properties of 1160 peptides were determined using the peptide package of R studio. Di- and tripeptides were mostly released with a molecular weight of 170 to 350 Da. PeptideRanker was used to select 16 peptides from a pool of 1160 peptides based on their likelihood of being bioactive. Molecular docking was performed by DS 2020 and AutoDock Vina, which revealed that the stability of the ligand-receptor complex is due to hydrogen bonding and electrostatic and hydrophobic interactions. Their binding energies ranged from -31.81 to -20.09 kJ/mol. For drug-likeness evaluation, an online tool SwissADME was used that follows the ADME rule (absorption, distribution, metabolism, and excretion) to check the pharmacokinetics and drug-likeness of the compound. In the future, the released peptides can be used to make functional nutraceutical foods against hypertension.

ACE inhibitory activities of two peptides derived from Volutharpa ampullacea perryi hydrolysate and their protective effects on H2O2 induced HUVECs injury

The purpose of this study is to explore the effects of IVTNWDDMEK and VGPAGPRG, two angiotensin I-converting enzyme (ACE) inhibitory peptides purified from Volutharpa ampullacea perryi, on ACE’s two domains and on nitric oxide (NO), endothelin-1(ET-1) production in human vascular endothelial cells (HUVECs). In addition, we sought to investigate the effects of these two peptides on HUVECs injury induced by H2O2. The results indicated that the inhibition of the ACE C-domain was significantly higher than that of the ACE N-domain by these two peptides. Molecular dynamics (MD) analysis revealed that the hydrogen bonds interactions between ACE and two peptides, the chelation between peptides and Zn2+ both play important role, which might contribute significantly to the ACE inhibitory activity. Two peptides significantly increase NO and ET-1 production in a dose-dependent manner and protects against hydrogen peroxide-induced HUVEC cell injury. The reported results also show that two peptides up-regulated the expression of nuclear factor erythroid 2-related factor (Nrf2) and heme oxygenase-1 (HO-1), and reduce the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA). Our study indicated that IVTNWDDMEK and VGPAGPRG could be potent ACE inhibitors and Volutharpa ampullacea perryi is a good source of bioactive peptides, which provided a theoretical basis for the broad application of two selected peptides as functional food with anti-hypertensive activity.

Exploring the potential of Lactobacillus and Saccharomyces for biofunctionalities and the release of bioactive peptides from whey protein fermentate

Whey protein concentrate-80 (WPC-80) fermented with L. fermentum (KGL4) (37 °C) and S. cerevisiae (WBS2A) (25 °C) was tested for ACE-inhibitory and antioxidant activities over different periods (12, 24, 36 and 48 h). Proteolytic activity (OPA method) was used to optimize the growth conditions (inoculation rate, i.e. at 1.5%, 2.0%, and 2.5% and incubation time, i.e. 12, 24, 36, and 48 h) for peptide production. Results indicated that the highest amount of peptides was obtained at 7.24 mg/mL for KGL4 (37 °C, 48 h) and 8.59 mg/mL for WBS2A (25 °C, 48 h). The whey protein fermentate inhibited the LPS-induced NO production, while enhanced production concentrations of TNF-α, IL-6, and IL-1β. Subsequently, SDS-PAGE, as well as Two-Dimensional (2D) gel electrophoresis methods, were applied for protein purification using water-soluble extracts (WSEs) of WPC-80 fermented by a combination of L. fermentum and S. cerevisiae. On SDS-PAGE, protein bands were observed in the range of 10–55 kDa, whereas on the 2D page, protein spots were in the range of 10–70 kDa. All the 2D spots were analyzed using RPLC/MS. WSEs of 3 kDa and 10 kDa permeates were used in RP-HPLC to identify distinct peptide fractions. The data from LC/MS was also characterized by utilizing ProteinPilot software. Further, different functional groups were also analyzed using FTIR investigation. The research aims to isolate and characterize novel ACE-inhibitory and antioxidative peptides from fermented WPC-80 produced by Lactobacillus fermentum and S. cerevisiae.

Two Novel Antihypertensive Peptides Identified in Millet Bran Glutelin-2 Hydrolysates: Purification, In Silico Characterization, Molecular Docking with ACE and Stability in Various Food Processing Conditions.

The addition of food-derived antihypertensive peptides to the diet is considered a reasonable antihypertension strategy. However, data about the stability of antihypertensive peptides in different food processing conditions are limited. In this study, through Sephadex G-15 gel chromatography and RP-HPLC separation, UPLC–ESI–MS/MS analysis and in silico screening, two novel ACE-inhibitory peptides, Pro-Leu-Leu-Lys (IC50: 549.87 μmol/L) and Pro-Pro-Met-Trp-Pro-Phe-Val (IC50: 364.62 μmol/L), were identified in millet bran glutelin-2 hydrolysates. The inhibition of angiotensin-I converting enzyme and the potential safety of PLLK and PPMWPFV were studied using molecular docking and in silico prediction, respectively. The results demonstrated that PLLK and PPMWPFV could non-competitively bind to one and seven binding sites of ACE through short hydrogen bonds, respectively. Both PLLK and PPMWPFV were resistant to different pH values (2.0–10.0), pasteurization conditions, addition of Na+, Mg2+ or K+ and simulated gastrointestinal digestion. However, PLLK and PPMWPFV were unstable upon heat treatment at 100 °C for more than 20 min or treatment with Fe3+ or Zn2+. In fact, treatment with Fe3+ or Zn2+ induced the formation of PLLK–iron or PLLK–zinc chelates and reduced the ACE-inhibitory activity of PLLK. These results indicate that peptides derived from millet bran could be added to foods as antihypertension agents.

Current Trends and Applications of Food-derived Antihypertensive Peptides for the Management of Cardiovascular Disease.

Food-derived antihypertensive peptides are considered a natural supplement for controlling hypertension. Food protein serves as a macronutrient and acts as a raw material for the biosynthesis of physiologically active peptides. Food sources, like milk and milk products, animal proteins such as meat, chicken, fish, eggs, and plant-derived proteins from food products like soy, rice, wheat, mushroom, and pumpkins contain higher quantities of antihypertensive peptides. The food-derived antihypertensive peptides can suppress the action of renin and the angiotensinconverting enzyme (ACE), which are mainly involved in the regulation of blood pressure by RAS. ACE inhibitory peptides enhance endothelial nitric oxide's biosynthesis, which increases nitric oxide production in vascular walls and encourages vasodilation. The peptides also inhibit the interaction between angiotensin II and its receptor, which helps reduce hypertension. This review explores the novel sources and applications of food-derived peptides for the management of hypertension.

Novel ACE inhibitory peptides derived from whey protein hydrolysates: Identification and molecular docking analysis

Angiotensin I-converting enzyme (ACE) plays a significant role in the regulation of blood pressure via generating angiotensin II (Ang II). Using natural inhibitors to block the activity of ACE is an alternative method to minimize the side effects of commercial drugs, and is a major goal of hypertension management. This study detected the presence of ACE inhibitory peptides in whey protein hydrolysate. The whey protein hydrolysate was separated sequentially by ultrafiltration and RP-HPLC. LC-MS/MS revealed the amino acid sequences of the fractions and four potential ACE inhibitory peptides were selected (PQVSTPTL, MPGP, PMHIR, PPLT) for synthesis. IC50 values of these four peptides were 86 ± 8, 179 ± 4, 90 ± 6, and 168 ± 4 μM, respectively. Then, molecular docking analysis was used to assess how these peptides interact with ACE. PQVSTPTL exhibited the lowest binding energy (−6.64 kcal/mol) with the ACE molecule. These four reported peptides were with no allergenicity nor toxicity. These results indicated that whey protein hydrolysate could be a suitable resource for obtaining novel inhibitory peptides against ACE and provides information for obtaining novel ACE inhibitors for hypertension management.

Exploration of corn distillers solubles from selective milling technology as a novel source of plant-based ACE inhibitory protein hydrolysates

Plant-based protein concentrate (PC) was extracted from under-utilized corn distillers solubles comprising a distinctive heat-treated blend of corn and yeast proteins. Enzymolysis of PC with alcalase generated protein hydrolysate (PH) containing angiotensin converting enzyme (ACE) inhibitory peptides. A novel kinetic model is developed to elucidate enzymolysis kinetics of PC. The PH of greatest DH (∼25%) revealed maximum ACE inhibition (%). Fractionated PH (<3 kDa) had non-toxic and non-allergenic unique peptides encrypted with anti-ACE fragments. Promising bioactive peptides (PeptideRanker > 0.85) docked with ACE had free energies between −8.40 and −10.60 kcal.mol−1 greater than captopril (−6.34 kcal.mol−1). The yeast-derived RLLPF peptide interacted with all active pockets of ACE (S1, S2, S’) via hydrogen-, polar- and hydrophobic-bonds. Docking results suggested that ARG522, VAL518, TRP357, TYR523, GLU384, ALA356, ARG124, HIS387, HIS410, ASN66, and ALA354 of ACE aided in stabilizing complexes with peptides. Thus, PH could be used as antihypertensive ingredient for feed, food, or pharmaceutical industries.

Bioactivities of Mealworm (Alphitobius diaperinus L.) Larvae Hydrolysates Obtained from Artichoke (Cynara scolymus L.) Proteases.

Simple SummaryEdible insects can provide an alternative and sustainable source of dietary protein to meet the future demand of the growing global population. Therefore, this study analysed the impact of mealworm (Alphitobius diaperinus L.) larvae hydrolysis using artichoke (Cynara scolymus L.) flower’s enzyme extract, on the production of peptide hydrolysates with potential bioactivity. The antioxidant capacity against the 1,1,-diphenil-2-picrylhydrazyl (DPPH) radical and the angiotensin-I-converting enzyme inhibitory activity of the hydrolysates were determined. Furthermore, the identification of the peptide sequences was conducted to detect the potential bioactive peptides in the hydrolysates. The results reveal that the water-soluble extract of artichoke flower could be suitable for producing bioactive peptides from mealworm larvae, and could be incorporated as an ingredient in future functional food products.In this study, we aimed to obtain hydrolysates with bioactive peptides from mealworm (Alphitobius diaperinus L.) larvae using an artichoke (Cynara scolymus L.) enzyme extract. Two types of substrates were used: the raw larvae flour (LF) and its protein extract (PE). The hydrolysis yield, considering the peptide concentration of the hydrolysates, was higher in PE hydrolysates than in LF hydrolysates (6.39 ± 0.59 vs. 3.02 ± 0.06 mg/mL, respectively). However, LF showed a higher antioxidant activity against the DPPH radical than PE (59.10 ± 1.42 vs. 18.79 ± 0.81 µM Trolox Eq/mg peptides, respectively). Regarding the inhibitory activity of angiotensin-I-converting enzyme (ACE), an IC50 value of 111.33 ± 21.3 µg peptides/mL was observed in the PE. The identification of the peptide sequence of both hydrolysates was conducted, and LF and its PE presented 404 and 116 peptides, respectively, most with low molecular weight (<3 kDa), high percentage of hydrophobic amino acids, and typical characteristics of well-known antioxidant and ACE-inhibitory peptides. Furthermore, the potential bioactivity of the sequences identified was searched in the BIOPEP database. Considering the antioxidant and ACE-inhibitory activities, LF hydrolysates contained a larger number of sequences with potential bioactivity than PE hydrolysates.

ACE-inhibitory activities of peptide fractions (

In this study, the effects of five adjunct lactobacilli on the formation of angiotensin-converting enzyme inhibitory (ACE-i) peptides in model cheeses were investigated. A total of seven peptide fractions (less than 3 kDa) were obtained by means of a fraction collector coupled with a HPLC system. ACE-i activity and peptide sequence analysis of the seven fractions were determined by RP-HPLC and then MALDI-ToF-MS techniques, respectively. Peptides produced from αs1- and κ-caseins had higher amounts compared to those produced by other caseins. There were considerable differences between the fractions in terms of peptide sequences and ACE-i activities. In general, the peptide fraction containing Lactobacillus delbrueckii ssp. bulgaricus exhibited a higher level of ACE-i activity (79.56%) than the other samples. The next highest ACE-i activity was determined in the cheese containing L. plantarum and significant differences were observed between the ACE-i activities of the fractions. The highest ACE-i activity was identified in fractions including f1 (51.39%) for L. casei, f6 (33.49%) for L. helveticus, f4 (46.62%) for L. helveticus DPC4571 and f1 (47.96%) for cheese containing non-adjunct culture. In conclusion, use of lactobacilli as an adjunct in model cheese increased the peptide types and amounts and also ACE-i activity.