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

Discovery of novel DPP4 inhibitory peptides from egg yolk by machine learning and molecular docking: In vitro and in vivo validation

DPP4 inhibitors could treat T2DM. Low-cost and accessible egg yolk protein (EYP) has the potential to produce highly bioactive peptides. Therefore, this study was to explore the novel DPP4 inhibitory peptide in EYP. The optimal protease (alcalase and pepsin) was screened using virtual enzymatic digestion. 61 potential peptides were filtered by ultrafiltration, LC-MS/MS, activity prediction and physicochemical property calculations. Then peptides RYHFPEGL, EYF, KFL, YKF and AAQEKIRYW were obtained by machine learning, BIOPEP database and molecular docking. AAQEKIRYW had outstanding hypoglycemia efficacy by in vitro cellular assay and mice plasma assay, with IC50 36.65 μM. Molecular docking and MD revealed that AAQEKIRYW-DPP4 complex was stably bound to S1 and S2' pockets of protein through hydrophilic (hydrogen bonding and electrostatic interactions) and hydrophobic interactions. It will provide a new insight for high-value utilization of EYP and a reference for the efficient screening and mechanism resolution of highly active peptides.

Discovery of two novel ACE inhibitory peptides from soybeans: Stability, molecular interactions, and in vivo antihypertensive effects

Functional peptides that are derived from natural protein-rich foods possess a wide range of physiological and pharmacological properties and have become ideal alternatives to chemical drugs. In this study, two novel ACE inhibitory peptides, GKGLW (IC50 = 34.96 μM) and GDGLKW (IC50 = 33.98 μM), were screened and identified from soybeans through sequential stepwise double enzymolysis, and their molecular mechanisms were explored by combining computational simulation. Initially, the optimal combination of alkaline protease and chymotrypsin was determined through the analysis of the enzymatic preferences of five different proteases and the ACE inhibitory activity of their hydrolyzed products. Following purification by ultrafiltration and Sephadex G-25 gel chromatography, the amino acid sequences of the peptides were identified by LC-MS/MS and selectively synthesized based on binding energy. Molecular docking and dynamics simulation/generalized born surface area calculation indicated that the peptides mainly interacted with key residues Ala354, Tyr523, and His353 in the ACE active pocket through hydrogen bonds, and hydrophobic and aromatic amino acids were beneficial to the ACE inhibitory activity of the peptides. Additionally, the two peptides showed good stability in simulating the gastrointestinal digestion process. The antihypertensive effects of these two peptides were further verified in a spontaneously hypertensive rats (SHRs) model. In conclusion, this study successfully identified two ACE inhibitory peptides, GKGLW and GDGLKW, from soybeans by combining proteases with different characteristics for stepwise degradation of soy protein, revealing their potential application value as antihypertensive functional foods.

Pyridine Derivatives and Furan Derivatives Identified From the Medicinal Mushroom Irpex lacteus SY1002

Three new pyridine derivatives, irpelactedines A-C (1-3), and a new furan derivative, irpelactedine D (5), along with two structurally related known compounds, irpexidine A (4) and 5-carboxy-2-furanpropanoic acid (6), were isolated from the medicinal fungus Irpex lacteus SY1002. Their structures were elucidated through nuclear magnetic resonance and mass spectral analyses, combined with density functional theory calculations of electronic circular dichroism data. Evaluation of angiotensin-converting enzyme (ACE) inhibitory activity revealed that compounds 1 and 3 displayed moderate inhibition, with IC50 values of 31.49 ± 3.41 and 80.96 ± 6.93 µg/mL, respectively. Molecular docking suggested that compound 1 is bound to the active site of ACE, leading to a reduction in its activity. Furthermore, cytotoxicity and antimicrobial activity tests revealed the low toxicity of these compounds. This is the first report on the ACE inhibitory activity of this class of pyridine derivatives, providing valuable insights into exploring the medicinal potential of I. lacteus and offering a structural template for developing new ACE inhibitors. Future efforts will focus on optimizing their structure and conducting in vivo testing to assess their therapeutic potential.

Integrated network pharmacology and experimental validation to explore the mechanisms of Coregonus peled-derived myosin ACE-inhibiting peptides for the treatment of hypertension

Coregonus peled is rich in protein and is a plentiful resource of bioactive peptides. This study was aimed at extracting novel Angiotensin I-converting enzyme (ACE) inhibitory peptides from Coregonus peled and revealing their potential hypotensive mechanisms. This paper screened six ACE inhibitory peptides with high bioactivity, good water solubility, and ADMET properties by computerized enzyme digestion of myosin-heavy chain from Coregonus peled, and LCYPR had the greatest ACE inhibition activity (IC50 = 47.8782 μM). There were 47 potentially critical targets of LCYPR for hypertension treatment, involving 135 biological processes (BP), 30 cellular components (CC), and 30 molecular functions (MF). The results of KEGG pathway analyse showed that the LCYPR participated in 50 pathways including the renin-angiotensin system, renin secretion, lipid and atherosclerosis, relaxin signaling pathway, IL-17 signaling pathway, atherosclerosis, fluid shear stress, and others, through the key targets such as AGT, AKT1, ACE, REN, CTSB, STAT3, PLG, SRC, MMP2, and F2 to regulate the blood pressure of organisms. In conclusion, the study obtained a novel ACE inhibitory peptide from the myosin-heavy chain of Coregonus peled and revealed the potential target and pathway of LCYPR to improve hypertension. The study provides new ideas and methods for developing novel antihypertensive peptides. The results provide a theoretical basis for developing functional foods of the Xinjiang specialty cold-water fish.

A peptide from Boletus griseus-Hypomyces chrysospermus protects against hypertension and associated cardiac and renal damage through modulating RAAS and intestinal microbiota

Hypertension is a major risk factor for many cardiovascular diseases, which can lead to kidney and heart disease, stroke, and premature death. Inhibiting angiotensin-converting enzyme (ACE) activity is an effective method to relieve hypertension. Previously, we screened an active peptide KYPHVF (KF6) from Boletus griseus-Hypomyces chrysospermus with excellent ACE inhibitory activity. This study further evaluated the antihypertensive activity of the KF6 in vivo. KF6 at 10 mg/kg and Captopril (CAP, a positive control) at 10 mg/kg were administrated to spontaneous hypertensive rats (SHRs) for 5 weeks. The results demonstrated that KF6 effectively lowered both diastolic blood pressure (DBP) and systolic blood pressure (SBP), and decreased ACE, AGT, ALD, and ANG II levels in the serum of SHRs. Furthermore, both cardiac and renal injury of SHRs were ameliorated by KF6 through inhibiting fibrosis, inflammation, and oxidative stress. Moreover, KF6 inhibited ACE-ANG II-AT1 axis while activating the ACE2-Ang (1-7)-MAS1L pathway, two mutually antagonistic axes of RAAS, in the kidney and heart of SHRs. Additionally, KF6 improved intestinal microbiota composition, mainly by increasing the abundance of Prevotella and Phascolarctobacterium while decreasing the abundance of Alistipes, Clostridium_IV, Nosocomiicoccus, and Allobaculum. Overall, KF6 is a promising ACE inhibitory peptide for lowering blood pressure and mitigating hypertension-related cardiac and renal damage. The protective effect of KF6 against hypertension is attributed to its ability to modulate RAAS and intestinal microbiota.

Exploring the efficacy of some biologically active compounds as anti-hypertensive drugs: an insightful evaluation through DFT, molecular docking and molecular dynamics simulations

Among different anti-hypertensive drugs, calcium channel blockers and human angiotensin-converting enzyme (ACE) inhibitors are the two main types. Herein, we took 25 biologically active ligands with potent anti-hypertensive activities and performed molecular docking studies with the human ACE receptor (PDB ID 1O8A) and human leukocyte antigens (HLA) complex, human voltage-dependent calcium channel alpha1 subunit (PDB ID 3LV3). Beforehand, we had performed density functional theory (DFT) studies to find out their structure-property relationships. In-silico ADMET studies were conducted, and we found that all 25 ligands follow Lipinski's Rule of 5, which confirms their oral bioavailability and high gastrointestinal absorption as a drug. Finally, molecular dynamics (MD) simulation studies were performed for the two top-scored drugs for 100 ns which reveal that a strong influence of the ligand (flunarizine) is there over the respective proteins.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-024-00291-4.

Immunomodulatory effects of inulin-type fructans from Arctium lappa L. by targeting gut microbiota and their metabolites

This study aimed to examine the in vitro digestion properties and immunomodulatory effects of inulin-type fructans (ALP-1) from Arctium lappa L. on immunosuppressive mice and to explore the underlying mechanisms. The simulated gastrointestinal digestion showed that ALP-1 underwent slight degradation during gastric and intestinal fluid digestion, with most of it reaching the gut as long-chain structures. The administration of ALP-1 effectively improved overall health and regulated immune function according to the spleen index, thymus index, splenic T-lymphocyte subsets, and other immune-related cytokines. Besides, 16S rDNA sequencing, ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry, and matrix-assisted laser desorption/ionization mass spectrometry imaging technique revealed fructan-induced changes in gut microbiota composition, metabolic processes, and spatial information of key metabolites. These changes likely contributed to the immunomodulatory effects of ALP-1 in immunosuppressive mice. Therefore, ALP-1 shows promise as an immunomodulator for use in functional foods and nutraceuticals.

A novel ACE inhibitory peptide from Douchi hydrolysate: Stability, inhibition mechanism, and antihypertensive potential in spontaneously hypertensive rats

Angiotensin I-converting enzyme (ACE) regulates blood pressure through the renin-angiotensin system. Douchi, a traditional fermented soybean condiment, may have antihypertensive effects, but research on ACE inhibitory peptides from Douchi hydrolysates is limited. We hypothesized that enzymatic treatment could enhance ACE inhibitory peptide diversity and efficacy. We tested ten single enzymes and four combinations, finding pepsin-trypsin-chymotrypsin most effective. Hydrolysates were purified using Sephadex G-15 and reversed-phase HPLC, and peptides were identified via LC-MS/MS. Five peptides (LF, VVF, VGAW, GLFG, NGK) were identified, with VGAW as the most potent ACE inhibitor (IC50 46.6 ± 5.2 μM) showing excellent thermal and pH stability. Lineweaver-Burk plots confirmed competitive inhibition, and molecular docking revealed eight hydrogen bonds between VGAW and ACE. In hypertensive rats, VGAW significantly reduced blood pressure at 12.5, 25, and 50 mg/kg. These findings highlight Douchi as a source of ACE inhibitory peptides and suggest VGAW as a promising functional food ingredient.

Research on the Synergistic Inhibition of Angiotensin-Converting Enzyme (ACE) by the Gastrointestinal Digestion Products of the ACE Inhibitory Peptide FPPDVA

To gain a deeper understanding of the ACE inhibition effect, the inhibitory effect of ACE-inhibiting peptide (ACEIP) FPPDVA's digestive products on ACE was further investigated. Two novel peptides, PD (IC50 = 161.1 ± 1.10 μM) and DV (IC50 = 66.51 ± 0.99 μM) were identified in the digestive products of FPPDVA using LC-MS/MS. The Peptide Mix (FPPDVA, PD, and DV) exhibited a remarkable synergistic effect on ACE inhibition by significantly enhancing it by up to 508% compared to the individual peptides alone. Furthermore, theoretical simulations suggest that the Peptide Mix synergistically inhibits ACE activity by forming more stable complexes with the active site of ACE, facilitated by an increased number of hydrogen bonds. Additionally, Lineweaver-Burk plot analysis and spectroscopic studies further verified the presence of these stable complexes. ITC results show that the combination of Peptides Mix and ACE is a spontaneous exothermic process driven by entropy. The study showed that FPPDVA has a stronger inhibitory effect on ACE after digestion, making it suitable as an antihypertensive peptide in functional foods.

Predicting variable-length ACE inhibitory peptides based on graph convolutional network

Traditional molecular descriptors have contributed to the prediction of angiotensin I-converting enzyme (ACE) inhibitory peptides, but they often fall short in capturing the complex structure of the molecule. To address these limitations, this study introduces molecular graphs as an advanced method for peptide characterization. Peptides containing 2-10 amino acids were represented using molecular graphs, and a graph convolutional network (GCN) model was constructed to predict variable-length peptides. This model was compared with machine learning (ML) models based on molecular descriptors, including Random Forest (RF), Support Vector Machine (SVM), and k-Nearest Neighbor (kNN), under the same benchmark. Notably, the GCN model outperformed the other models with an accuracy of 0.78, effectively identifying ACE inhibitory potential. Furthermore, the GCN model also demonstrated superior performance, exceeding existing methods with an accuracy rate of over 98 % on an independent test set. To validate our predictions, we synthesized peptides VAPE and AQQKEP with high predicted probabilities, and their IC50 values of 2.25 ± 0.11 and 3.75 ± 0.17 μM, respectively, indicating potent ACE inhibitory activity. The developed GCN model presents a powerful tool for the rapid screening and identification of ACE inhibitory peptides, offering promising opportunities for developing antihypertensive components in functional foods.

Characterization, mechanisms, structure-activity relationships, and antihypertensive effects of ACE inhibitory peptides: rapid screening from sufu hydrolysate

This study investigates the characterization, mechanisms of action, structure-activity relationships, and in vivo antihypertensive effects of ACE inhibitory peptides derived from sufu hydrolysate following simulated gastrointestinal digestion. Sufu was enzymatically digested using pepsin, trypsin, and chymotrypsin to mimic gastrointestinal conditions, followed by ultrafiltration to fractionate the peptides based on molecular weight. The fraction under 1 kDa exhibited the highest ACE inhibitory activity. LC-MS/MS analysis identified 119 peptide fragments, with bioinformatics screening highlighting 41 peptides with potential ACE inhibitory properties. Among these, two peptides, AWR and LLR, were selected and synthesized for in vitro validation, displaying IC50 values of 98.04 ± 2.56 μM and 94.01 ± 5.07 μM, respectively. Stability tests showed that both peptides maintained their ACE inhibitory activity across various temperatures and pH levels. Molecular docking and Highest Occupied Molecular Orbital analysis indicated strong binding interactions between these peptides and ACE, with the second-position tryptophan in AWR and the N-terminal leucine in LLR identified as key bioactive sites. These findings were further supported by molecular dynamics simulations, which confirmed the stability of the peptide-ACE complexes. In vivo studies using spontaneously hypertensive rats demonstrated significant reductions in both systolic and diastolic blood pressure, indicating that AWR and LLR have strong antihypertensive potential. This study illustrates that ultrafiltration, combined with LC-MS/MS and bioinformatics analysis, is an effective approach for the rapid screening of ACE inhibitory peptides. These results not only enhance our understanding of sufu-derived peptides but also offer promising implications for hypertension management.

Emerging production techniques and potential health promoting properties of plant and animal protein-derived bioactive peptides

Bioactive peptides (BPs) are short amino acid sequences that that are known to exhibit physiological characteristics such as antioxidant, antimicrobial, antihypertensive and antidiabetic properties, suggesting that they could be exploited as functional foods in the nutraceutical industry. These BPs can be derived from a variety of food sources, including milk, meat, marine, and plant proteins. In the past decade, various methods including in silico, in vitro, and in vivo techniques have been explored to unravel underlying mechanisms of BPs. To forecast interactions between peptides and their targets, in silico methods such as BIOPEP, molecular docking and Quantitative Structure-Activity Relationship modeling have been employed. Additionally, in vitro research has examined how BPs affect enzyme activities, protein expressions, and cell cultures. In vivo studies on the contrary have appraised the impact of BPs on animal models and human subjects. Hence, in the light of recent literature, this review examines the multifaceted aspects of BPs production from milk, meat, marine, and plant proteins and their potential bioactivities. We envisage that the various concepts discussed will contribute to a better understanding of the food derived BP production, which could pave a way for their potential applications in the nutraceutical industry.

Garlic and Hypertension: Efficacy, Mechanism of Action, and Clinical Implications

Hypertension is a major risk factor for heart disease and stroke. Garlic has a long history of use in traditional medicine for various conditions, including hypertension. This narrative review examined the scientific evidence on the efficacy of garlic in lowering blood pressure. It explores the historical uses of garlic in different cultures for medicinal purposes and delves into the phytochemical composition of garlic, highlighting key components, like allicin and ajoene, that are believed to contribute to its potential health benefits. Clinical studies that investigated the effects of garlic and garlic-based supplements on blood pressure are presented, with the findings suggesting that garlic consumption may modestly reduce blood pressure, particularly in individuals with mild hypertension. Potential mechanisms of action include increased nitric oxide production, improved endothelial function, and antioxidant properties. While garlic may offer some benefits for blood pressure management, it should not be considered a substitute for conventional antihypertensive medications. Further large-scale, long-term clinical trials are warranted to establish the efficacy of garlic in managing hypertension, including the optimal dosage and formulation.

Identification, screening and molecular mechanisms of natural stable angiotensin-converting enzyme (ACE) inhibitory peptides from foxtail millet protein hydrolysates: a combined in silico and in vitro study

The stability of bioactive peptides under various food processing conditions is the basis for their use in industrial manufacturing. This study aimed to identify natural ACE inhibitors with excellent stability and investigate their physicochemical properties and putative molecular mechanisms. Five novel ACE inhibitory peptides (QDPLFPL, FPGVSPF, SPAQLLPF, LVPYRP, and WYWPQ) were isolated and identified using RP-HPLC and Nano LC-MS/MS with foxtail millet protein hydrolysates as the raw material. These peptides are non-toxic and exhibit strong ACE inhibitory activity in vitro (IC50 values between 0.13 mg mL-1 and 0.56 mg mL-1). In addition to QDPLFPL, FPGVSPF, SPAQLLPF, LVPYRP, and WYWPQ have excellent human intestinal absorption. Compared to FPGVSPF and SPAQLLPF, the stable helical structure of LVPYRP and WYWPQ allows them to maintain high stability under conditions that mimic gastrointestinal digestion and various food processing (temperatures, pH, sucrose, NaCl, citric acid, sodium benzoate, Cu2+, Zn2+, K+, Mg2+, Ca2+). The results of molecular docking and molecular dynamics simulation suggest that LVPYRP has greater stability and binding capacity to ACE than WYWPQ. LVPYRP might attach to the active pockets (S1, S2, and S1') of ACE via hydrogen bonds and hydrophobic interactions, then compete with Zn2+ in ACE to demonstrate its ACE inhibitory activity. The binding of LVPYRP to ACE enhances the rearrangement of ACE's active structural domains, with electrostatic and polar solvation energy contributing the most energy to the binding. Our findings suggested that LVPYRP derived from foxtail millet protein hydrolysates has the potential to be incorporated into functional foods to provide antihypertensive benefits.

Food-Derived Up-Regulators and Activators of Angiotensin Converting Enzyme 2: A Review

Angiotensin-converting enzyme 2 (ACE2) is a key enzyme in the renin-angiotensin system (RAS), also serving as an amino acid transporter and a receptor for certain coronaviruses. Its primary role is to protect the cardiovascular system via the ACE2/Ang (1-7)/MasR cascade. Given the critical roles of ACE2 in regulating numerous physiological functions, molecules that can upregulate or activate ACE2 show vast therapeutic value. There are only a few ACE2 activators that have been reported, a wide range of molecules, including food-derived compounds, have been reported as ACE2 up-regulators. Effective doses of bioactive peptides range from 10 to 50 mg/kg body weight (BW)/day when orally administered for 1 to 7 weeks. Protein hydrolysates require higher doses at 1000 mg/kg BW/day for 20 days. Phytochemicals and vitamins are effective at doses typically ranging from 10 to 200 mg/kg BW/day for 3 days to 6 months, while Traditional Chinese Medicine requires doses of 1.25 to 12.96 g/kg BW/day for 4 to 8 weeks. ACE2 activation is linked to its hinge-bending region, while upregulation involves various signaling pathways, transcription factors, and epigenetic modulators. Future studies are expected to explore novel roles of ACE2 activators or up-regulators in disease treatments and translate the discovery to bedside applications.

Bioavailability and Metabolism of Bioactive Peptide IRW with Angiotensin-Converting Enzyme 2 (ACE2) Upregulatory Activity in Spontaneously Hypertensive Rats

Peptide IRW is the first food-derived angiotensin-converting enzyme 2 (ACE2) upregulator. This study aimed to investigate the pharmacokinetic characteristics of IRW and identify the metabolites contributing to its antihypertensive activity in spontaneously hypertensive rats (SHRs). Rats were administered 100 mg of IRW/kg of the body weight via an intragastric or intravenous route. The bioavailability (F %) was determined to be 11.7%, and the half-lives were 7.9 ± 0.5 and 28.5 ± 6.8 min for gavage and injection, respectively. Interestingly, significant blood pressure reduction was not observed until 1.5 h post oral administration, or 2 h post injection, indicating that the peptide's metabolites are likely responsible for the blood pressure-lowering activity. Time-course metabolomics revealed a significant increase in the level of kynurenine, a tryptophan metabolite, in blood after IRW administration. Kynurenine increased the level of ACE2 in cells. Oral administration of tryptophan (W), but not dipeptide IR, lowered the blood pressure and upregulated aortic ACE2 in SHRs. Our study supports the key role of tryptophan and its metabolite, kynurenine, in IRW's blood pressure-lowering effects.