ACE-inhibitory Peptides Research Articles

Discovery of a novel nanomolar angiotensin-I converting enzyme inhibitory peptide with unusual binding mechanisms derived from Chlorella pyrenoidosa

Chlorella pyrenoidosa (C. pyrenoidosa) has been cultivated in large quantities, and was proven to be antihypertensive when consumed orally. However, the antihypertensive peptides derived from C. pyrenoidosa remains scarce. In this study, trypsin was chosen to prepare the hydrolysate of C. pyrenoidosa, which was then fractionated by column chromatography. And ninety-nine peptides were identified by LC-MS/MS, after which 10 peptides were chosen by docking-based virtual screening and demonstrated the ability to inhibit ACE. Among them, LVAKA (LV-5) had the lowest IC50 (26.66 μM). LV-5, LKKAP, and PGLRP were identified as non-competitive ACE inhibitory peptides that exhibited significant stability in the face of extreme pH and high temperatures. Insilico and in-vitro simulated gastrointestinal digestion revealed that these three peptides could release ACE inhibitory peptide fragments after digestion. The sequence optimization of LV-5 led to the identification of LRAKA (LR-5), which was recognized as a novel nanomolar ACE peptide with an IC50 of 350 nM in-vitro and a potent antihypertensive effect in-vivo. Moreover, molecular dynamic simulation indicated that LR-5 interacted with an unconventional binding site in ACE. These findings underscore the potential of Chlorella as a source of antihypertensive peptides and suggest a promising future for the use of Chlorella-derived peptides in the management of hypertension.

Goat Milk Protein-Derived ACE Inhibitory Peptide SLPQ Exerts Hypertension Alleviation Effects Partially by Regulating the Inflammatory Stress of Endothelial Cells

Hypertension has always posed a severe threat to people’s health. Food-derived angiotensin-converting enzyme (ACE)-inhibitory peptides have the potential to both prevent and treat hypertension. In the current investigation, two ACE-inhibitory peptides (SLPQ and PYVRYL) from goat milk were studied for their endothelial effects using EA.hy926 cells. PYVRYL outperformed SLPQ, yet neither impacted cell survival below 200 μg/mL. Investigation of SLPQ’s impact on EA.hy926 cell expression revealed 114 differentially expressed genes, with 65 downregulated and 49 upregulated. The genes were enriched in cytokine interactions, coagulation cascades, Hippo signaling, and ECM–receptor interaction. Decreased c-x-c motif chemokine ligand 2 (CXCL2), integrin subunit beta 2 (ITGB2), and fbj murine osteosarcoma viral oncogene homologue (FOS) expression and increased secreted phosphoprotein 1 (SPP1) expression may protect endothelial cells from inflammation. Our findings suggest that beyond ACE inhibition, SLPQ aids blood pressure control by influencing endothelial function, paving the way for its use as an antihypertensive 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.

Novel Bioactive Peptides from Red Bigeye (Priacanthus macracanthus) Flesh Protein

Red bigeye (Priacanthus macracanthus) is a common fish species in Malaysia. This study reported an in silico assessment of the main proteins in red bigeye flesh as precursors for bioactive peptides. Six major proteins were chosen as precursors from the proteomic profiles of red bigeye proteins. Analyses using the BIOPEP-UWM database found that Protein number 4 gave the highest total number of bioactive peptides (5052 peptides), with dominant bioactivity in angiotensin-I-converting enzyme (ACE) inhibition (1571 peptides) and dipeptidyl peptidase-IV (DPP-IV) inhibition (2238 peptides). The ACE inhibitors had a frequency of bioactive fragment occurrences (A) of 0.4098, while the DPP-IV inhibitors gave a frequency of 0.5805. In silico proteolysis using BIOPEP-UWM found that pepsin (pH > 2) was the most promising proteinase in releasing a high number of DPP-IV and ACE inhibitory peptides. A novel peptide with significant potential was identified as QYKF. This study shows that red bigeye is a potential source of antihypertensive and antidiabetic peptides.

From Sea to Lab: Angiotensin I-Converting Enzyme Inhibition by Marine Peptides-Mechanisms and Applications.

To reveal potent ACE inhibitors, researchers screen various bioactive peptides from several sources, and more attention has been given to aquatic sources. This review summarizes the recent research achievements on marine peptides with ACE-inhibitory action and application. Marine peptides are considered excellent bioactives due to their large structural diversity and unusual bioactivities. The mechanisms by which these marine peptides inhibit ACE include competitive binding to ACEs' active site, interfering with ACE conformational changes, and avoiding the identification of substrates. The unique 3D attributes of marine peptides confer inhibition advantages toward ACE activity. Because IC50 values of marine peptides' interaction with ACE are low, structure-based research assumes that the interaction between ACE and peptides increased the therapeutic application. Numerous studies on marine peptides focused on the sustainable extraction of ACE-inhibitory peptides produced from several fish, mollusks, algae, and sponges. Meanwhile, their potential applications and medical benefits are worth investigating and considering. Due to these peptides exhibiting antioxidant, antihypertensive, and even antimicrobial properties simultaneously, their therapeutic potential for cardiovascular disease and other illnesses only increases. In addition, as marine peptides show better pharmacological benefits, they have increased absorption rates and low toxicity and could perhaps be modified for better stability and bioefficacy. Biotechnological advances in peptide synthesis and formulation have greatly facilitated the generation of peptide-based ACE inhibitors from marine sources, which subsequently offer new treatment models. This article gives a complete assessment of the present state of knowledge about marine organism peptides as ACE inhibitors. In addition, it emphasizes the relevance of additional investigation into their mechanisms of action, the optimization of manufacturing processes, and assessment in in vivo, preclinical, and clinical settings, underlining the urgency and value of this study. Using marine peptides for ACE inhibition not only broadens the repertory of bioactive compounds but also shows promise for tackling the global health burden caused by cardiovascular diseases.

Identification and Molecular Docking of ACE Inhibitory Peptides Derived from Sodium Substituted Cheddar Cheese

Identification and Molecular Docking of ACE Inhibitory Peptides Derived from Sodium Substituted Cheddar Cheese

Identification of New Angiotensin-Converting Enzyme Inhibitory Peptides Isolated from the Hydrolysate of the Venom of Nemopilema nomurai Jellyfish.

Recently, jellyfish venom has gained attention as a promising reservoir of pharmacologically active compounds, with potential applications in new drug development. In this investigation, novel peptides, isolated from the hydrolysates of Nemopilema nomurai jellyfish venom (NnV), demonstrate potent inhibitory activities against angiotensin-converting enzyme (ACE). Proteolytic enzymes-specifically, papain and protamex-were utilized for the hydrolysis under optimized enzymatic conditions, determined by assessing the degree of hydrolysis through the ninhydrin test. Comparative analyses revealed that papain treatment exhibited a notably higher degree of NnV hydrolysis compared to protamex treatment. ACE inhibitory activity was quantified using ACE kit-WST, indicating a substantial inhibitory effect of 76.31% for the papain-digested NnV crude hydrolysate, which was validated by captopril as a positive control. The separation of the NnV-hydrolysate using DEAE sepharose weak-anion-exchange chromatography revealed nine peaks under a 0-1 M NaCl stepwise gradient, with peak no. 3 displaying the highest ACE inhibition of 96%. The further purification of peak no. 3 through ODS-C18 column reverse-phase high-performance liquid chromatography resulted in five sub-peaks (3.1, 3.2, 3.3, 3.4, and 3.5), among which 3.2 exhibited the most significant inhibitory activity of 95.74%. The subsequent analysis of the active peak (3.2) using MALDI-TOF/MS identified two peptides with distinct molecular weights of 896.48 and 1227.651. The peptide sequence determined by MS/MS analysis revealed them as IVGRPLANG and IGDEPRHQYL. The docking studies of the two ACE-inhibitory peptides for ACE molecule demonstrated a binding affinity of -51.4 ± 2.5 and -62.3 ± 3.3 using the HADDOCK scoring function.

Preparation and stability of angiotensin-I-converting enzyme (ACE) inhibitory peptides from protein hydrolysate of Wuyi rock tea residues

ABSTRACT Wuyi rock tea residues, generated after brewing or aroma extraction, are rich in nutrients. This study aimed to prepare ACE inhibitory peptides from the protein hydrolysate of Wuyi rock tea residues and investigate their stability. The optimal proteolysis conditions for neutral protease were optimized as: a substrate concentration of 2% (w/v), pH 7.0, hydrolysis temperature of 45°C, enzymatic digestion time of 3 h, and enzyme dosage of 6800 U/g. Under these conditions, the ACE inhibition rate of protein hydrolysate of Wuyi rock tea residues reached 70.47 ± 0.29% at a concentration of 0.5 mg/mL. Additionally, the prepared ACE inhibitory peptides demonstrated excellent stability against acid, base, heat, and certain metal ions. These findings suggest that the proteins extracted from Wuyi rock tea residues can serve as a promising source to produce highly active ACE inhibitory peptides. These peptides could be utilized in the development of nutraceuticals, functional foods, and pharmaceuticals.

Angiotensin converting enzyme (ACE) inhibitory peptide from the tuna (Thunnus thynnus) muscle: Screening, interaction mechanism and stability

In this study, the purpose was to screen novel angiotensin converting enzyme inhibitory peptides (ACEIPs) from tuna muscle taking two-steps enzymatic hydrolysis (Neutrase and Alkaline). Following isolation and purification by ultrafiltration, the Sephadex G-15 gel chromatography and reversed-phase high-performance liquid chromatography based on active-guide, the amino acid sequence was identified using Q-Orbitrap-MS/MS. Five peptides were chose synthesized based on the in silico screening methods. Among these, the two novel ACEIPs LTGCP and YPKP showed better inhibitory ability, and their corresponding IC50 values were 64.3 μM and 139.6 μM. Subsequently, the interaction mechanism of the best active peptide (LTGCP) against ACE was investigated by inhibitory pattern, molecular docking and molecular dynamic simulation. The result displayed that LTGCP was a mix-type inhibitor against ACE from the Lineweaver-Burk plots. LTGCP formed seven hydrogen bonds based on the molecular docking and the binding energy was −7.29 kcal/mol. LTGCP formed a stability complex with ACE based on the molecular dynamic simulation. Besides, LTGCP exhibited good stability in various temperature, pH and gastrointestinal digestion. Finally, the 0.125 mM ∼ 1.0 mM LTGCP exhibited no-toxic for Caco-2 cell. In summary, these findings showed that tuna was a good material to prepare ACEIPs and LTGCP may be the good potential antihypertensive drug or nutraceuticals.

Preparation and Vasodilation Mechanism of Angiotensin-I-Converting Enzyme Inhibitory Peptide from Ulva prolifera Protein.

Ulva prolifera, a type of green algae that can be consumed, was utilized in the production of an angiotensin-I converting enzyme (ACE) inhibitory peptide. The protein from the algae was isolated and subsequently hydrolyzed using a neutral protease. The resulting hydrolysate underwent several processes including Sephadex-G100 filtration chromatography, ultrafiltration, HPLC-Q-TOF-MS analysis, ADMET screening, UV spectrum detection test, molecular docking, and molecular dynamic simulation. Then, the ACE inhibitory peptide named KAF (IC50, 0.63 ± 0.26 µM) was identified. The effectiveness of this peptide in inhibiting ACE can be primarily attributed to two conventional hydrogen bonds. Additionally, it could activate endothelial nitric oxide synthase (eNOS) activity to promote the generation of nitric oxide (NO). Additionally, KAF primarily increased the intracellular calcium (Ca2+) level by acting on L-type Ca2+ channel (LTCC) and the ryanodine receptor (RyR) in the endoplasmic reticulum, and completed the activation of eNOS under the mediation of protein kinase B (Akt) signaling pathway. Our study has confirmed that KAF has the potential to be processed into pharmaceutical candidate functions on vasoconstriction.

Investigation of the regulatory effect of α-chymotrypsin-assisted hydrolysate from Sebastes schlegelii on blood pressure through in vitro, in silico ACE inhibitory activity, and in vivo spontaneously hypertensive rat hypertensive model

This study aimed to screen peptides with antihypertensive effects from the α-chymotrypsin hydrolysate of Sebastes schlegelii (SSA). SSA demonstrated ACE inhibitory activity with an IC50 value of 0.062 ± 0.001 mg/mL. The SSA significantly reduced body weight and systolic blood pressure in the SHR spontaneously hypertensive rat (SHR) model and improved hypertension-induced vasopathy and interstitial fibrosis in heart and vascular tissues, indicating the presence of ACE inhibitory peptides contributing to cardiovascular health. Peptide composition analysis identified fractions of SSA with potent ACE inhibitory activity, particularly those with molecular weights of 5 kDa or less. Further evaluation of ACE activity using Sephadex G-10 separated SSA fractions led to the amino acid sequence analysis of the most effective fraction (SSA-F1). Molecular docking simulations predicted that peptides from SSA-F1 inhibit ACE activity by binding to its active sites. This research suggests the potential of peptides from S. schlegelii for clinical hypertension treatment.

A novel angiotensin I-converting enzyme inhibitory peptide APPLRP from Grifola frondosa ameliorated the Ang II-induced vascular modeling in zebrafish model by mediating smooth muscle cells

Grifola frondosa has garnered significant popularity as an edible mushroom attributable to its exceptional taste and nutritional benefits. This study isolated APPLRP, a potent ACE-inhibitory peptide, from the alcohol-soluble fraction of Grifola frondosa. The underlying mechanisms of APPLRP in antihypertension were explored through computational chemistry, cell experiments, and zebrafish model. Results demonstrated that APPLRP was an active competitive ACE inhibitor (IC50 = 29.93 μM) that could bind to the active pocket S2 and S1′ of ACE. APPLRP exhibited resistance to pepsin and pancreatin digestion. In vitro experiments revealed that APPLRP significantly attenuated Ang II-induced VSMCs proliferation and migration by down-regulating AT1R expression and inhibiting ERK1/2 and STAT3 phosphorylation. APPLRP intervention significantly ameliorated myocardial fibrosis, as evidenced by reductions in cardiac output, blood flow velocity, and cardiac collagen deposition levels in Ang II-induced hypertensive zebrafish model. Furthermore, APPLRP improved vascular remodeling in hypertensive zebrafish, indicated by increased vessel diameter and decreased vessel wall thickness. Notably, APPLRP treatment resulted in down-regulation of ACE and up-regulation of ACE2 expression in the vessels of hypertensive zebrafish. These findings indicated that APPLRP was a representative component of Grifola frondosa peptides, and its antihypertensive effects were associated with ACE inhibition and the improvement of VSMCs-mediated vascular remodeling.

Antihypertensive and Antidiabetic Drug Candidates from Milkfish (Chanos chanos)-Identification and Characterization through an Integrated Bioinformatic Approach.

Integrated bioinformatics tools have created more efficient and robust methods to overcome in vitro challenges and have been widely utilized for the investigation of food proteins and the generation of peptide sequences. This study aimed to analyze the physicochemical properties and bioactivities of novel peptides derived from hydrolyzed milkfish (Chanos chanos) protein sequences and to discover their potential angiotensin-converting enzyme (ACE)- and dipeptidyl peptidase-4 (DPPIV)-inhibitory activities using machine learning-based tools, including BIOPEP-UWM, PeptideRanker, and the molecular docking software HADDOCK 2.4. Nine and three peptides were predicted to have ACE- and DPPIV-inhibitory activities, respectively. The DPPIV-inhibitory peptides were predicted to inhibit the compound with no known specific mode. Meanwhile, two tetrapeptides (MVWH and PPPS) were predicted to possess a competitive mode of ACE inhibition by directly binding to the tetra-coordinated Zn ion. Among all nine discovered ACE-inhibitory peptides, only the PPPS peptide satisfied the drug-likeness analysis requirements with no violations of the Lipinski rule of five and should be further investigated in vitro.

Presence of Modified Peptides with High Bioavailability and Angiotensin-Converting Enzyme Inhibitory Activity in Japanese Fermented Soybean Paste (Miso).

Not only free amino acids and normal short-chain peptides but also modified amino acids, such as N-acetyl- and N-formyl amino acids, monoamines, polyamines, and modified peptides, such as isomerized aspartyl peptides, pyroglutamyl peptides, and diketopiperazines, were identified in Japanese fermented soy paste (miso) prepared using different fungal starters, rice, barley, and soybean-koji. One hour after oral administration of water extract of soybean-koji miso to rats, the modified peptides increased significantly in the lumen upon the ingestion, while the normal peptides did not. In the blood from the portal vein and abdominal vena cava, 17 and 15 diketopiperazines, 16 and 12 isomerized aspartyl peptides, and 2 and 1 pyroglutamyl peptides significantly increased to approximately 10-400 nM, respectively. The modified peptides, which increased in rat blood, showed angiotensin-converting enzyme (ACE) inhibitory activity in a dose-dependent manner, indicating multiple ACE inhibitory peptides with high bioavailability in miso. Among them, l-β-Asp-Pro showed the highest ACE inhibitory activity (IC50 4.8 μM).

Evaluation of In Vitro Antihypertensive and Anti-Inflammatory Properties of Dairy By-Products

Sweet whey (SW) and yogurt acid whey (YAW) are dairy by-products of the cheese-making process and Greek-style yogurt production, respectively. Both of them are considered pollutants with huge volumes of SW and YAW produced due to the growing demand for dairy products worldwide. Moreover, whey-derived peptides, resulting from fermentation as well as from further hydrolysis during digestion, have been associated with various biological activities. In the present study, the angiotensin-converting enzyme (ACE)-inhibitory activity of 48 SW samples and 33 YAW samples from bovine, ovine, caprine, and ovine/caprine milk obtained were evaluated. Additionally, the SW and YAW digestates and two of their fractions (smaller than 10 kDa, SW-D-P10 and YAW-D-P10, and smaller than 3 kDa, SW-D-P3 and YAW-D-P3), which were obtained after in vitro digestion and subsequent ultrafiltration, were also subjected to evaluation. Our data indicated that the D-P10 and D-P3 fractions exhibited higher ACE-inhibitory activity compared to the corresponding values before digestion. The ACE-inhibitory capacity after in vitro digestion was higher for the ovine SW samples compared to their bovine and caprine counterparts. The effect of the D-P3 fraction on the inhibition of nitric oxide (NO) production and the expression of a selected panel of immune-response-related genes in LPS-stimulated RAW 264.7 macrophages was also evaluated. Fractions from both dairy by-products inhibited NO production in LPS-stimulated RAW 264.7 cells. Especially, ovine SW-D-P3 showed a strong NO inhibitory activity and suppressed inducible nitric oxide synthase (Nos2) mRNA levels. However, YAW-D-P3 could not trigger neither the gene expression of inflammatory macrophage mediators Nos2 and cyclooxygenase-2 (Ptgs2) nor tumor necrosis factor-α (Tnf) and interleukin 6 (Il6) in LPS-stimulated murine macrophages regardless of animal origin. These findings suggest that in vitro digestion could enhance the production of ACE-inhibitory peptides in both dairy by-products, while SW from ovine origin displays higher potential as an anti-inflammatory agent, effectively preventing excessive NO production.

Chemical characterization and angiotensin-I converting enzyme inhibitory activity of Indonesian stinky beans

The chemical composition of four Indonesian stinky beans has been explored. Those bean are Petai (Parkia speciosa), Lamtoro Gung (Leucaena leucochepala ssp. Glabrata (Rose) S. Zarate), Jengkol (Pithecellobium jiringa) and Kabau (Archidendron bubalinum). This exploration belongs to the local food utilization research theme of functional food sources. Those beans have a unique flavour and usually lead to foul stools, sweat, urine or mouth odour. Their intense flavour may be due to the content of amino acids. High hydrophobic and negative charge hydrophilic amino acids are crucial in preventing hypertension through inhibition of angiotensin I-converting enzyme (ACE) activity. This study evaluated the chemical properties of beans and its angiotensin I-converting enzyme inhibitory (ACE-I) peptides. The amino acid profile was determined as preliminary data to ensure the content of hydrophobic and negative charge hydrophilic amino acids. Their ability to inhibit ACE was studied to represent an antihypertensive effect. In vitro gastrointestinal digestion was applied to obtain more small molecular peptides and evaluate their ACE-I activity after digestion. Petai has the highest glutamic acid (20.90 g/100 g protein d.b.), lysine (13.31 g/100 g protein d.b.), arginine (11.76 g/100 g protein d.b.), leucine (10.98 g/100 g protein d.b.), and aspartic acid (10.72 g/100 g protein d.b.). Fresh Jengkol has the highest ACE-I activity (67.59%). Subsequential digestion by pepsin and pancreatin improves the ACE-I activity, and Kabau had the highest (79.87%). Based on the results, Indonesian stinky beans can prevent hypertension by inhibiting ACE activity and being used as a protein source alternative

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.

Novel ACE-inhibiting peptides from soybean protein hydrolysates by peptidomics combined with in silico analysis and their inhibitory effects on proliferation and migration of Ang II-induced VSMCs

Novel ACE-inhibiting peptides from soybean protein hydrolysates by peptidomics combined with <i>in silico</i> analysis and their inhibitory effects on proliferation and migration of Ang II-induced VSMCs

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.

Angiotensin converting enzyme inhibitory hydrolysate and peptide fractions from chicken skin collagen, as modulators of lipid accumulation in adipocytes 3 T3-L1, after in vitro gastrointestinal digestion

Inhibitory activity against angiotensin-converting enzyme (IAACE) by chicken skin collagen hydrolysate (CSCH) and their peptide fractions before and after in-vitro gastrointestinal digestion, were evaluated; as well as their ability to modulate lipid accumulation in 3 T3-L1 adipocytes. Before digestion, peptide fraction <1 kDa (F4) showed the highest IAACE (p < 0.05) followed by CSCH. After these samples were digested, F4 presented an IAACE with IC50 similar to its digest (DF4) (188.84 and 220.03 μg/mL, respectively), which was 2-fold lower (p < 0.05) than IC50 of fraction <1 kDa from post-digested hydrolysate (FDH) (388.57 μg/mL). Nine peptides were identified as the potential ACE inhibitors in F4 and DF4. Addition of DF4 (800 μg/mL) reduced(p < 0.05) lipid accumulation by 83% within preadipocytes. A 45–60% reduction of lipid accumulation within differentiated adipocytes was obtained by adding FDH and DF4 (regardless the concentration). These results, digested CSCH and F4 with IAACE may be considered as potential adjuvants for obesity treatment.