Proteolysis and ACE-inhibitory peptide profile of Cheddar cheese: Effect of digestion treatment and different probiotics

The novel angiotensin-I-converting enzyme inhibitory peptides from Scomber japonicus muscle protein hydrolysates: QSAR-based screening, molecular docking, kinetic and stability studies

Food-derived angiotensin-converting enzyme-inhibitory (ACE-I) peptides have attracted extensive attention. Herein, the ACE-I peptides from Scomber japonicus muscle hydrolysates were screened, and their mechanisms of action and inhibition stability were explored. The quantitative structure-activity relationship (QSAR) model based on 5z-scale metrics was developed to rapidly screen for ACE-I peptides. Two novel potential ACE-I peptides (LTPFT, PLITT) were predicted through this model coupled with in silico screening, of which PLITT had the highest activity (IC50: 48.73 ± 7.59 μM). PLITT inhibited ACE activity with a mixture of non-competitive and competitive mechanisms, and this inhibition mainly contributed to the hydrogen bonding based on molecular docking study. PLITT is stable under high temperatures, pH, glucose, and NaCl. The zinc ions (Zn2+) and copper ions (Cu2+) enhanced ACE-I activity. The study suggests that the QSAR model is effective in rapidly screening for ACE-I inhibitors, and PLITT can be supplemented in foods to lower blood pressure.

Revealing the ACE receptor binding properties and interaction mechanisms of salty oligopeptides from Stropharia rugosoannulata mushroom by molecular simulation and antihypertensive evaluation

The salty oligopeptides from Stropharia rugosoannulata have been proven to be potential ACE inhibitors. To investigate the ACE receptor binding properties and interaction mechanisms of salty oligopeptides, the molecular interaction, dynamics simulation, and antihypertensive evaluation cross-validation strategy were employed to reveal the oligopeptides' binding reactions and modes with the ACE receptor. Single oligopeptide (ESPERPFL, KSWDDFFTR) had exothermic and specific binding reactions with the ACE receptor, driven by hydrogen bonds and van der Waals forces. The coexistence of the multiple oligopeptide molecules did not produce the apparent ACE receptor competition binding reactions. The molecular dynamics simulation verified that the two oligopeptides disturbed the ACE receptor's different residue regions. Both oligopeptides could form stable complexes with the ACE receptor. Based on the classification of 50 oligopeptides' binding modes, ESPERPFL and KSWDDFFTR belonged to different classes, and their receptor binding modes and sites complemented, resulting in a potential synergistic effect on ACE inhibition. The antihypertensive effect of KSWDDFFTR and its distribution in the body were evaluated using SHR rats orally and ICR mice by tail vein injection, and KSWDDFFTR had antihypertensive effects within 8 h. The study provides a theoretical basis for understanding salty oligopeptides' ACE receptor binding mechanism and their antihypertensive effects.

Two Novel Angiotensin-Converting Enzyme (ACE) Inhibitory and ACE2 Upregulating Peptides from the Hydrolysate of Pumpkin (Cucurbita moschata) Seed Meal

Pumpkin (Cucurbita moschata) seed meal (PSM), the major byproduct of pumpkin seed oil industry, was used to prepare angiotensin-converting enzyme (ACE) inhibitory and angiotensin-converting enzyme 2 (ACE2) upregulating peptides. These peptides were isolated and purified from the PSM hydrolysate prepared using Neutrase 5.0 BG by ultrafiltration, Sephadex G-15 column chromatography, and reversed-phase high-performance liquid chromatography. Two peptides with significant ACE inhibition activity were identified as SNHANQLDFHP and PVQVLASAYR with IC50 values of 172.07 and 90.69 μM, respectively. The C-terminal tripeptides of the two peptides contained Pro, Phe, and Tyr, respectively, and PVQVLASAYR also had Val in its N-terminal tripeptide, which was a favorable structure for ACE inhibition. Molecular docking results declared that the two peptides could interact with ACE through hydrogen bonds and hydrophobic interactions. Furthermore, the two peptides performed protective function on EA.hy926 cells by decreasing the secretion of endothelin-1, increasing the release of nitric oxide, and regulating the ACE2 activity. In vitro simulated gastrointestinal digestion showed the two peptides exhibited good stability against gastrointestinal enzyme digestion. In conclusion, PSM is a promising material for preparing antihypertensive peptides.

Impact of Lactiplantibacillus plantarum and casein fortification on angiotensin converting enzyme inhibitory peptides in yogurt: identification and in silico analysis

In this study, the effects of Lactiplantibacillus plantarum M11 (Lb. plantarum M11) in conjunction with sodium caseinate on the characteristics and angiotensin converting enzyme (ACE) inhibitory activity of yogurt were investigated. ACE inhibitory peptides (ACEIPs) in yogurt were identified by nano-LC-MS/MS and potential ACEIPs were predicted by in silico and molecular docking methods. The results showed that the ACE-inhibitory activity of yogurt was significantly enhanced (p < 0.05), while maintaining the quality characteristics of the yogurt. Thirteen ACEIPs in the improved yogurt (883 + M11-CS group) were identified, which were more abundant than the other yogurt groups (control 883 group, 883 + M11 group and 883-CS group). Two novel peptides with potential ACE inhibitory activity, YPFPGPIH and NILRFF, were screened. The two peptides showed PeptideRanker scores above 0.8, small molecular weight and strong hydrophobicity, and were non-toxic after prediction. Molecular docking results showed that binding energies with ACE were -9.4 kcal mol-1 and -10.7 kcal mol-1, respectively, and could bind to the active site of ACE. These results indicated that yogurt with Lb. plantarum M11 and sodium caseinate has the potential to be utilized as a functional food with antihypertensive properties. The combination of ACEIP-producing strains and casein fortification could be an effective method to promote the release of ACEIPs from yogurt.

Insights into characteristic metabolites and potential bioactive peptides profiles of fresh cheese fermented with three novel probiotics based metabolomics and peptidomics

The metabolite and peptide profiles of fresh cheese fermented by three novel probiotics, Lacticaseibacillus rhamnosus B6, Limosylactobacillus fermentum B44 and Lacticaseibacillus rhamnosus KF7, were investigated using LC-MS/MS-based metabolomics and peptidomics. The multivariate analysis revealed significant differences in metabolite composition between the probiotic fresh cheese and the control sample. The differential metabolites were primarily lipids and lipid-like molecules and organic oxygen compounds, which were associated with fatty acid and carbohydrate-related pathways. Among three probiotics, L. rhamnosus KF7 showed the highest effectiveness in sucrose decomposition. 147 potential bioactive peptides, mainly derived from casein, were identified in probiotic fresh cheese. Furthermore, 112 bioactive peptides were significantly up-regulated in probiotic fresh cheese. Molecular docking analysis indicated that two short peptides (LVYPFPGPIP and YPQRDMPIQ) in the B44 and KF7 groups exhibited low estimated binding energy values (-9.9 and -6.9 kcal/mol) with ACE. These findings provide a theoretical basis for developing novel probiotic-enriched fresh cheese.

Efficient preparation of oyster hydrolysate with aroma and umami coexistence derived from ultrasonic pretreatment assisted enzymatic hydrolysis

In the study, an efficient protease Neutrase®-Flavourzyme® (NF) was screened to prepare the umami-aroma flavor oyster hydrolysate. The effect of protease and ultrasonic pretreatment (UP) assisted by the optimal protease on the flavor substances was investigated. The results demonstrated that the optimal UP-NF (450 W) showed a higher amino acid nitrogen content of 0.34 g/100 mL compared to the NF, and 19 major aroma compounds including octanal, decanal, nonanal, benzaldehyde, 2-undecanone, and 1-octen-3-ol were obtained. Additionally, the free amino acid and fatty acid spectrum indicated that the formation of flavor compounds was primarily due to the oxidation of linoleic and linolenic acids and the degradation of amino acids. Furthermore, taste analysis proved that increased umami and saltiness resulted from the accelerated release of Glu, Asp and 5'-IMP. Overall, UP-NF proved to be an effective method for producing umami-aroma flavor, facilitating further processing of oyster products for the application.

Biodirected Screening and Preparation of Larimichthys crocea Angiotensin-I-Converting Enzyme-Inhibitory Peptides by a Combined In Vitro and In Silico Approach

Food-derived angiotensin-I-converting enzyme (ACE)-inhibitory peptides have gained attention for their potent and safe treatment of hypertensive disorders. However, there are some limitations of conventional methods for preparing ACE-inhibitory peptides. In this study, in silico hydrolysis, the quantitative structure-activity relationship (QSAR) model, LC-MS/MS, inhibition kinetics, and molecular docking were used to investigate the stability, hydrolyzability, in vitro activity, and inhibition mechanism of bioactive peptides during the actual hydrolysis process. Six novel ACE-inhibitory peptides were screened from the Larimichthys crocea protein (LCP) and had low IC50 values (from 0.63 ± 0.09 µM to 10.26 ± 0.21 µM), which were close to the results of the QSAR model. After in vitro gastrointestinal simulated digestion activity of IPYADFK, FYEPFM and NWPWMK were found to remain almost unchanged, whereas LYDHLGK, INEMLDTK, and IHFGTTGK were affected by gastrointestinal digestion. Meanwhile, the inhibition kinetics and molecular docking results were consistent in that ACE-inhibitory peptides of different inhibition forms could effectively bind to the active or non-central active centers of ACE through hydrogen bonding. Our proposed method has better reproducibility, accuracy, and higher directivity than previous methods. This study can provide new approaches for the deep processing, identification, and preparation of Larimichthys crocea.

Screening of Oral Potential Angiotensin-Converting Enzyme Inhibitory Peptides from Zizyphus jujuba Proteins Based on Gastrointestinal Digestion In Vivo

Plant proteins are a good source of active peptides, which can exert physiological effects on the body. Predicting the possible activity of plant proteins and obtaining active peptides with oral potential are challenging. In this study, the potential activity of peptides from Zizyphus jujuba proteins after in silico simulated gastrointestinal digestion was predicted using the BIOPEP-UWM™ database. The ACE-inhibitory activity needs to be further investigated. The actual peptides in mouse intestines after the oral administration of Zizyphus jujuba protein were collected and analyzed, 113 Zizyphus jujuba peptides were identified, and 3D-QSAR models of the ACE-inhibitory activity were created and validated using a training set (34 peptides) and a test set (12 peptides). Three peptides, RLPHV, TVKPGL and KALVAP, were screened using the 3D-QSAR model and were found to bind to the active sites of the ACE enzyme, and their IC50 values were determined. Their values were 6.01, 3.81, and 17.06 μM, respectively. The in vitro digestion stabilities of the RLPHV, TVKPGL, and KALVAP peptides were 82%, 90%, and 78%. This article provides an integrated method for studying bioactive peptides derived from plant proteins.

Proteolysis and therapeutic potential of bioactive peptides derived from Cheddar cheese

Cheddar cheese-derived bioactive peptides are considered a potential component of functional foods. A positive impact of bioactive peptides on diet-related chronic, non-communicable diseases, like obesity, cardiovascular diseases, and diabetes, has been observed. Bioactive peptides possess multifunctional therapeutic potentials, including antimicrobial, immunomodulatory, antioxidant, enzyme inhibitory effects, anti-thrombotic, and phyto-pathological activities against various toxic compounds. Peptides can regulate human immune, gastrointestinal, hormonal, and neurological responses, which play an integral role in the deterrence and treatment of certain diseases like cancer, osteoporosis, hypertension, and other health disorders, as described in the present review. This review summarizes the categories of the Cheddar cheese-derived bioactive peptides, their general characteristics, physiological functions, and possible applications in healthcare.

Investigating structure, biological activity, peptide composition and emulsifying properties of pea protein hydrolysates obtained by cell envelope proteinase from Lactobacillus delbrueckii subsp. bulgaricus

We present the structure, biological activity, peptide composition, and emulsifying properties of pea protein isolate (PPI) after hydrolysis by cell envelope proteinase (CEP) from Lactobacillus delbrueckii subsp. bulgaricus. Hydrolysis resulted in the unfolding of the PPI structure, characterized by an increase in fluorescence and UV absorption, which was related to thermal stability as demonstrated by a significant increase in ΔH and the thermal denaturation temperature (from 77.25 ± 0.05 to 84.45 ± 0.04 °C). The hydrophobic amino acid of PPI significantly increased from 218.26 ± 0.04 to 620.77 ± 0.04 followed by 557.18 ± 0.05 mg/100 g, which was related to their emulsifying properties, with the maximum emulsifying activity index (88.62 ± 0.83 m2/g, after 6 h hydrolysis) and emulsifying stability index (130.77 ± 1.12 min, after 2 h hydrolysis). Further, the results of LC-MS/MS analysis demonstrated that the CEP tended to hydrolyze peptides with an N-terminus dominated by Ser and a C-terminus dominated by Leu, which enhanced the biological activity of pea protein hydrolysates, as supported by their relatively high antioxidant (ABTS+ and DPPH radical scavenging rates were 82.31 ± 0.32% and 88.95 ± 0.31%) and ACE inhibitory (83.56 ± 1.70%) activities after 6 h of hydrolysis. 15 peptide sequences (score > 0.5) possessed both antioxidant and ACE inhibitory activity potential according to the BIOPEP database. This study provides theoretical guidance for the development of CEP-hydrolyzed peptides with antioxidant and ACE inhibitory activity that can be used as emulsifiers in functional foods.

Formation and inhibition mechanism of novel angiotensin I converting enzyme inhibitory peptides from Chouguiyu

Angiotensin I converting enzyme (ACE) inhibitory peptides from fermented foods exhibit great potential to alleviate hypertension. In this study, the peptide extract from Chouguiyu exhibited a good inhibition effect on ACE, and the inhibition rate was significantly enhanced after fermentation for 8 days. The ACE inhibitory peptides were further identified, followed by their inhibition and formation mechanisms using microbiome technology and molecular docking. A total of 356 ACE inhibitory peptides were predicted using in silico, and most ACE inhibitory peptides increased after fermentation. These peptides could be hydrolyzed from 94 kinds of precursor proteins, mainly including muscle-type creatine kinase, nebulin, and troponin I. P1 (VEIINARA), P2 (FAVMVKG), P4 (EITWSDDKK), P7 (DFDDIQK), P8 (IGDDPKF), P9 (INDDPKIL), and P10 (GVDNPGHPFI) were selected as the core ACE inhibitory peptides according to their abundance and docking energy. The salt bridge and conventional hydrogen bond connecting unsaturated oxygen atoms in the peptides contributed most to the ACE inhibition. The cleavage proteases from the microbial genera in Chouguiyu for preparing these 7 core ACE inhibitory peptides were further analyzed by hydrolysis prediction and Pearson's correlation. The correlation network showed that P7, P8, and P9 were mainly produced by the proteases from LAB including Lactococcus, Enterococcus, Vagococcus, Peptostreptococcus, and Streptococcus, while P1, P2, P4, and P10 were mainly Produced by Aeromonas, Bacillus, Escherichia, and Psychrobacter. This study is helpful in isolating the proteases and microbial strains to directionally produce the responding ACE inhibitory peptides.

Discovery and functional mechanism of novel dipeptidyl peptidase Ⅳ inhibitory peptides from Chinese traditional fermented fish (Chouguiyu)

Dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides from fermented foods exhibit great potential to alleviate type 2 diabetes mellitus (T2DM). In this study, the DPP-IV inhibition activity of peptide extract from Chouguiyu was obviously enhanced after 4–8 d fermentation. A total of 125 DPP-IV inhibitory peptides in Chouguiyu were identified by peptidomics and were obtained from 46 precursor proteins, mainly including nebulin, titin, muscle-type creatine kinase, hemoglobin, and actin. After molecular docking with DPP-IV, four novel DPP-IV inhibitory peptides possessing the lowest docking energy were selected, including EPAEAVGDWR (D37), IPHESVDVIK (D22), PDLSKHNNHM (D35), and PFGNTHNNFK (D1). The DPP-IV inhibition activity of D37, D22, D35, and D1 were further verified after synthesis with the IC₅₀ of 0.10 mM, 2.69 mM, 3.88 mM, and 8.51 mM, respectively, in accordance with their docking energies. Energy interaction showed that the structures of EP-, IPH-, -NHM, and PF- in these peptides were easy to connect with DPP-IV enzyme through hydrogen bond, salt bridge, and alkyl. The surface force including the H-bond interaction, hydrophobicity, aromatic interaction, and SAS, played a major role in the interaction between DPP-IV enzyme and peptides. The peptides that possess high hydrophobicity and can form strong hydrogen bond and salt bridge are potential DPP-IV inhibitory peptides using for T2DM remission.

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DPP-Ⅳ inhibition activity of peptide extract in Chouguiyu increased by fermentation.

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The main precursor proteins of DPP-Ⅳ inhibitory peptides were nebulin and titin.

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Inhibition mechanism was explored by energy interaction and surface force.

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Docking energy was an effective index to select DPP-IV inhibitory peptides.

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DPP-IV inhibitory peptides formed hydrogen bond and salt bridge with DPP-IV.

Exploring the DPP-IV Inhibitory, Antioxidant and Antibacterial Potential of Ovine "Scotta" Hydrolysates

The aim of this work was to valorize the by-product derived from the ricotta cheese process (scotta). In this study, ovine scotta was concentrated by ultrafiltration and then subjected to enzymatic hydrolyses using proteases of both vegetable (4% E:S, 4 h, 50 °C) and animal origin (4% E:S, 4 h, 40 °C). The DPP-IV inhibitory, antioxidant, and antibacterial activities of hydrolysates from bromelain (BSPH) and pancreatin (PSPH) were measured in vitro. Both the obtained hydrolysates showed a significantly higher DPP-IV inhibitory activity compared to the control. In particular, BSPH proved to be more effective than PSPH (IC₅₀ 8.5 ± 0.2 vs. 13 ± 1 mg mL⁻¹). Moreover, BSPH showed the best antioxidant power, while PSPH was more able to produce low-MW peptides. BSPH and PSPH hydrolysates showed a variable but slightly inhibitory effect depending on the species or strain of bacteria tested. BSPH and PSPH samples were separated by gel permeation chromatography (GPC). LC-MS/MS analysis of selected GPC fractions allowed identification of differential peptides. Among the peptides 388 were more abundant in BSPH than in the CTRL groups, 667 were more abundant in the PSPH group compared to CTRL, and 97 and 75 of them contained sequences with a reported biological activity, respectively.

Comparative Peptidomics Analysis of Fermented Milk by Lactobacillus delbrueckii ssp. bulgaricus and Lactobacillus delbrueckii ssp. lactis

Few studies have investigated the peptidomics of fermented milk by Lactobacillus delbrueckii. The aim of the present study was to interpret the peptidomic pattern of the fermented milk by five strains of L. delbrueckii ssp. bulgaricus and ssp. lactis prior to and after the simulated gastrointestinal digestion in vitro. The results indicated variations in the peptidomics among the samples, particularly between the samples of different subspecies. The peptides originating from β-casein were abundant in the samples of ssp. bulgaricus, whereas the peptides derived from αs1-casein and αs2-casein were more likely to dominate in those of ssp. lactis. For β-casein, the strains of ssp. bulgaricus displayed extensive hydrolysis in the regions of (73–97), (100–120), and (130–209), whereas ssp. lactis mainly focused on (160–209). The digestion appears to reduce the variations of the peptidomics profile in general. Among the five strains, L. delbrueckii ssp. bulgaricus DQHXNS8L6 was the most efficient in the generation of bioactive peptides prior to and after digestion. This research provided an approach for evaluating the peptide profile of the strains during fermentation and digestion.

Eating Fermented: Health Benefits of LAB-Fermented Foods

Lactic acid bacteria (LAB) are involved in producing a considerable number of fermented products consumed worldwide. Many of those LAB fermented foods are recognized as beneficial for human health due to probiotic LAB or their metabolites produced during food fermentation or after food digestion. In this review, we aim to gather and discuss available information on the health-related effects of LAB-fermented foods. In particular, we focused on the most widely consumed LAB-fermented foods such as yoghurt, kefir, cheese, and plant-based products such as sauerkrauts and kimchi.