Novel angiotensin-converting enzyme inhibitory peptides derived from Trichiurus lepturus myosin: Molecular docking and surface plasmon resonance study

In vitro inhibitor effect and molecular docking of thiamine (vitamin B1), riboflavin (vitamin B2), and reference inhibitor captopril on angiotensin-converting enzyme purified from sheep plasma

OBJECTIVE

Angiotensin-converting enzyme (ACE, EC 3.4.15.1) is a very important factor in the regulation of blood pressure. Also, the inhibition of ACE with natural compounds has been a very important research area in the treatment of high blood pressure. ACE was purified and characterized from sheep plasma. Molecular docking studies and the inhibition effect of thiamine, riboflavin, and captopril on ACE were investigated.

METHODS

Herein, ACE was purified from sheep plasma by affinity chromatography. The effect of thiamine and riboflavin on ACE was researched. Molecular docking studies were performed to understand the molecular interactions between thiamine, riboflavin, and captopril with ACE.

RESULTS

The purification coefficient was found to be 8636 fold. The binding energy of thiamine, riboflavin, and captopril was found to be -6.7 kcal/mol, -8.1 kcal/mol, and -5.5 kcal/mol, respectively. Thiamine conformed to three conventional hydrogen bonds with ASP:415, HIS:513, and LYS:454. Riboflavin formed four conventional hydrogen bonds with GLN:281, GLU:376, THR:282, and TYR:520. Captopril formed two conventional hydrogen bonds with ARG:124, one conventional hydrogen bond with TYR:62 and ASN:85, and one carbon-hydrogen bond with ASN:66. Molecular docking results showed that thiamine, riboflavin, and captopril interacted with ACE through hydrogen bonding and hydrophobic interactions. Thiamine and riboflavin indicated significant inhibition effects on ACE. The IC50 values of thiamine, riboflavin, and captopril were found as 960.56 µM, 11.02 µM, and 1.60 nM, respectively. Ki values for thiamine, riboflavin, and captopril were determined as 1352.04 µM, 12.30 µM, and 1.06 nM, respectively.

CONCLUSION

In this work, it was concluded that thiamine and riboflavin may have preventive and therapeutical impacts against high blood pressure with their ACE inhibitor effect. Thiamine and riboflavin showed a lower inhibitory effect with a higher IC50 than captopril. However, when the inhibitory effect of thiamine and riboflavin vitamins is compared to captopril, it is concluded that they may be natural inhibitors with fewer side effects.

Valorization of fish processing by-products for protein hydrolysate recovery: Opportunities, challenges and regulatory issues

Protein-rich fish processing by-products, often called rest raw materials (RRM), account for approximately 60% of the total fish biomass. However, a considerable amount of these RRM is utilized for low-value products such as fish meal and silage. A promising and valuable approach for maximizing the utilization of RRM involves the extraction of bioactive fish protein hydrolysate (FPH). This review assesses and compares different hydrolyzation methods to produce FPH. Furthermore, the review highlights the purification strategy, nutritional compositions, and bioactive properties of FPH. Finally, it concludes by outlining the application of FPH in food products together with various safety and regulatory issues related to the commercialization of FPH as a protein ingredient in food. This review paves the way for future applications by highlighting efficient biotechnological methods for valorizing RRM into FPH and addressing safety concerns, enabling the widespread utilization of FPH as a valuable and sustainable source of protein.

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

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

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.

Identification and In Silico Analysis of ACE-Inhibitory Peptides Derived from Milk Fermented by Lacticaseibacillus paracasei

Inhibition of angiotensin I-converting enzyme (ACE) activity is an effective way to treat hypertension. In the present study, the ability to produce ACE-inhibitory peptides during fermentation of skimmed milk by the Lacticaseibacillus paracasei M3 strain was evaluated, and the inhibitory mechanism and stability were studied by bioinformatics analysis. The results showed that the ACE inhibition activity of fermented milk was 71.94 ± 1.39%. After digestion with gastric juice and pancreatic juice, the ACE inhibitory activities of the fermented milk were 78.40 ± 1.93 and 74.96 ± 1.73%, respectively. After the fermented milk was purified using ultrafiltration and gel chromatography, 11 peptides from milk proteins were identified and sequenced by Nano LC-MS/MS. Molecular docking displayed that peptide PWIQPK had a high affinity, with ACE showing a binding energy of -6.10 kcal/mol. Hydrogen bonds were formed between PWIQPK and Glu384 in the S1 active pocket of ACE and Asp358. In addition, van der Waals forces were observed. In silico proteolysis suggested that PWIQPK could resist the digestion of pepsin and trypsin, indicating that it is relatively stable in the digestive tract. All results indicate that milk fermented by L. paracasei M3 has the potential to be used as a functional food having antihypertensive effects.

Angiotensin-Converting Enzyme (ACE) Inhibitory Activity and Mechanism Analysis of N-(1-Deoxy-d-fructos-1-yl)-histidine (Fru-His), a Food-Derived Amadori Compound

N-(1-Deoxy-d-fructos-1-yl)-histidine (Fru-His), one of the Amadori compounds, widely presents in processed foods, and its potential functional activities have attracted extensive attention in recent years. In this work, the angiotensin-converting enzyme (ACE) inhibitory activity and mechanism of Fru-His were investigated. The IC₅₀ value of Fru-His was 0.150 ± 0.019 mM, and there was no obvious degradation of Fru-His after digestion simulation, showing that Fru-His has good ACE inhibition and digestive stability. Fru-His was a competitive inhibitor according to the enzyme inhibition kinetic analysis. The interaction between ACE and Fru-His occurred spontaneously mainly through hydrogen bonding, and the process was accompanied by fluorescence quenching and the alteration of the secondary structure of ACE. The molecular docking data supported the above results. Fru-His was attached to ACE's S1 active pocket through hydrogen bonds and interacted with zinc ions in active sites. The present study demonstrates that food-derived Fru-His has the potential to relieve hypertension.

Identification of α-glucosidase inhibitors from the bran of Chenopodium quinoa Willd. by surface plasmon resonance coupled with ultra-performance liquid chromatography and quadrupole-time-of-flight-mass spectrometry

Extracts from the bran of Chenopodium quinoa Willd. (QBE) were reported to be active in inhibiting α-glycosidase, a promising target for treatment of diabetes mellitus. However, the constituents responsible for the α-glucosidase-inhibiting activity of QBE have not been fully characterized. The present study aimed to set up a method for rapid identification of glycosidase inhibiting compounds from the quinoa bran. With surface plasmon resonance (SPR) coupled with liquid chromatography-mass spectrometry (LC-MS), we identified eight flavonoids and ten triterpenoid saponins that may bind to the α-glycosidase. Analysis of the interaction kinetics by molecular docking supported their α-glucosidase-inhibiting activity and revealed the potential mechanisms for the inhibitory effects. In summary, this study established a SPR and LC-MS-based method for rapid in vitro screening of α-glucosidase inhibitors and suggested the quinoa bran a potential natural source of α-glucosidase inhibitors.

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

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

Peptide late-stage C(sp3)-H arylation by native asparagine assistance without exogenous directing groups

There is a strong demand for novel native peptide motifs for post-synthetic modifications of peptides without pre-installation and subsequent removal of directing groups. Herein, we report an efficient method for peptide late-stage C(sp3)-H arylations assisted by the unmodified side chain of asparagine (Asn) without any exogenous directing group. Thereby, site-selective arylations of C(sp3)-H bonds at the N-terminus of di-, tri-, and tetrapeptides have been achieved. Likewise, we have constructed a key building block for accessing agouti-related protein (AGRP) active loop analogues in a concise manner.

Surface plasmon resonance analysis for detecting non-structural protein 1 of dengue virus in Indonesia

Dengue is an acute febrile disease caused by dengue virus (DENV) that is transmitted by Aedes sp., which causes serious health conditions in many countries. Non-structural protein 1 (NS1) is a co-factor for the RNA replication of this virus, which represents a new strategy for the identification of dengue. Prompt and accurate laboratory diagnosis of this infection is required to assist in patient triage and management, as well as prevent the spread of this infection. In the present study, we tested the potential of surface plasmon resonance (SPR) as a diagnostic tool for dengue infections. NS1 antigen protein was used as an analyte that targets anti-NS1 antibodies, with their interaction resulting in a change in the refractive index. In comparison to currently available gold-standard detection methods [enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR)], SPR showed a similar sensitivity but greater efficiency and simplicity in terms of infection detection. Out of 26 samples collected from patients with dengue in Indonesia, SPR was able to correctly identify all 16 positively infected individuals at a lower concentration and a shorter period of time compared to ELISA and RT-PCR. This study revealed that SPR is a promising tool for DENV detection and potentially other diseases as well.

Anti-Hypertensive Activity of Novel Peptides Identified from Olive Flounder (Paralichthys olivaceus) Surimi

There is a growing interest in the health benefits of functional foods. A benefit that has been long sought is the control of hypertension through dietary approaches. Hypertension has been implicated as a risk factor for cardiovascular disease and is therefore of clinical significance. Here, we aim to demonstrate the antihypertensive activity of novel peptides derived from surimi, a functional food ingredient made from refined fish myofibrillar proteins. Three peptides, Ile-Val-Asp-Arg (IVDR), Trp-Tyr-Lys (WYK), and Val-Ala-Ser-Val-Ile (VASVI), were isolated from surimi made from the olive flounder (Paralichthys olivaceus). Our results show that IVDR, WYK, and VASVI exhibited high Angiotensin I-converting Enzyme (ACE) inhibition activity. These peptides are also shown to increase phosphorylation of protein kinase B (Akt) and endothelial nitric oxide synthase (eNOS), and significantly promote nitric oxide (NO) production in human umbilical vein endothelial cells. Oral administration of the peptides decreased blood pressure in spontaneously hypertensive rats (SHRs), thereby confirming that the peptides derived from surimi perform antihypertensive activity via the Akt/eNOS pathway. These results indicate that surimi made from P. olivaceus contains novel antihypertensive peptides that could be used to enhance the health benefits of food ingredients.

Antihypertensive effects of Trichiurus lepturus myosin hydrolysate in spontaneously hypertensive rats

In this study, the blood pressure-lowering effects of Trichiurus lepturus myosin hydrolysate (TMH) and its possible mechanism were investigated in spontaneously hypertensive rats (SHRs). After gavage administration of TMH for 4 h, systolic blood pressure (SBP) was significantly decreased in SHRs. Furthermore, the SBP of SHRs remained low at 1 month after daily TMH treatment at 400 mg kg-1. Meanwhile, plasma levels of angiotensin II, bradykinin and nitric oxide in SHRs were ameliorated by TMH. Western blotting also suggested that TMH down-regulated the expression of ICAM-1 and VCAM-1, indicating a strong anti-inflammatory effect. Additionally, nitrotyrosine and collagen I were down-regulated, revealing a significant anti-oxidant effect of TMH. No obvious side effects or toxicity were observed in normal Wistar rats given TMH. Various pathogenic factors related to hypertension were improved by TMH, which may explain the underlying mechanism by which TMH synergistically reduces blood pressure.

Novel ACE Inhibitory Peptides Derived from Simulated Gastrointestinal Digestion in Vitro of Sesame (Sesamum indicum L.) Protein and Molecular Docking Study

The aim of this study was to isolate and identify angiotensin I-converting enzyme (ACE) inhibitory peptides from sesame protein through simulated gastrointestinal digestion in vitro, and to explore the underlying mechanisms by molecular docking. The sesame protein was enzymatically hydrolyzed by pepsin, trypsin, and α-chymotrypsin. The degree of hydrolysis (DH) and peptide yield increased with the increase of digest time. Moreover, ACE inhibitory activity was enhanced after digestion. The sesame protein digestive solution (SPDS) was purified by ultrafiltration through different molecular weight cut-off (MWCO) membranes and SPDS-VII (< 3 kDa) had the strongest ACE inhibition. SPDS-VII was further purified by NGC Quest™ 10 Plus Chromatography System and finally 11 peptides were identified by Nano UHPLC-ESI-MS/MS (nano ultra-high performance liquid chromatography-electrospray ionization mass spectrometry/mass spectrometry) from peak 4. The peptide GHIITVAR from 11S globulin displayed the strongest ACE inhibitory activity (IC50 = 3.60 ± 0.10 μM). Furthermore, the docking analysis revealed that the ACE inhibition of GHIITVAR was mainly attributed to forming very strong hydrogen bonds with the active sites of ACE. These results identify sesame protein as a rich source of ACE inhibitory peptides and further indicate that GHIITVAR has the potential for development of new functional foods.

Considerations for Docking of Selective Angiotensin-Converting Enzyme Inhibitors

The angiotensin-converting enzyme (ACE) is a two-domain dipeptidylcarboxypeptidase, which has a direct involvement in the control of blood pressure by performing the hydrolysis of angiotensin I to produce angiotensin II. At the same time, ACE hydrolyzes other substrates such as the vasodilator peptide bradykinin and the anti-inflammatory peptide N-acetyl-SDKP. In this sense, ACE inhibitors are bioactive substances with potential use as medicinal products for treatment or prevention of hypertension, heart failures, myocardial infarction, and other important diseases. This review examined the most recent literature reporting ACE inhibitors with the help of molecular modeling. The examples exposed here demonstrate that molecular modeling methods, including docking, molecular dynamics (MD) simulations, quantitative structure-activity relationship (QSAR), etc, are essential for a complete structural picture of the mode of action of ACE inhibitors, where molecular docking has a key role. Examples show that too many works identified ACE inhibitory activities of natural peptides and peptides obtained from hydrolysates. In addition, other works report non-peptide compounds extracted from natural sources and synthetic compounds. In all these cases, molecular docking was used to provide explanation of the chemical interactions between inhibitors and the ACE binding sites. For docking applications, most of the examples exposed here do not consider that: (i) ACE has two domains (nACE and cACE) with available X-ray structures, which are relevant for the design of selective inhibitors, and (ii) nACE and cACE binding sites have large dimensions, which leads to non-reliable solutions during docking calculations. In support of the solution of these problems, the structural information found in Protein Data Bank (PDB) was used to perform an interaction fingerprints (IFPs) analysis applied on both nACE and cACE domains. This analysis provides plots that identify the chemical interactions between ligands and both ACE binding sites, which can be used to guide docking experiments in the search of selective natural components or novel drugs. In addition, the use of hydrogen bond constraints in the S₂ and S₂′ subsites of nACE and cACE are suggested to guarantee that docking solutions are reliable.