Strong ACE-inhibitory Activity Research Articles

Olive Pomace Extract Contains Low Molecular Weight Peptides and Possesses ACE Inhibitory Activity.

The aim of the present study was to determine the ACE inhibitory activity of aqueous extracts of olive pomace and to understand whether they represent a good source of bioactive LMW peptides for nutritional and pharmacological applications. We produced a water extract from olive pomace (var. Picual) and obtained its low molecular weight (LMW) fraction (<3 kDa). The calculated yield of extraction was 100.2 ± 7.9 mg of LMW peptides per 100 g of olive pomace. The olive pomace LMW fraction possessed strong ACE inhibitory activity (IC50 = 3.57 ± 0.22 µg prot/mL). The LMW fraction (<3 kDa) was analysed by nanoscale liquid chromatography-Orbitrap coupled with tandem mass spectrometry and de novo sequencing. Thirty new peptides, containing between 7-17 amino acids and molecular masses ranging 778-1354 Da, were identified by the Peaks database algorithm using the available Olea europaea (cv. Farga) genome database. Ten new peptides were also identified by Peaks de novo sequencing. The protein sources of twelve peptides detected in the database by Peaks DB were identified by BLAST search. The ACE inhibitory activity of the identified peptides was predicted by BIOPEP software. We conclude that olive pomace possesses ACE inhibitory activity and contains low molecular weight peptides with (predicted) biological activity. Olive pomace may represent a good source of peptides for nutritional and pharmaceutical applications. In our study, it has been shown that olive pomace possesses ACE inhibitory activity and contains low molecular weight peptides with (predicted) biological activity. Olive pomace may represent a good source of peptides for nutritional and pharmaceutical applications. More research is needed in order to identify the in vivo effects of olive pomace bioactive peptides.

Characterisation of Bioactive Peptides from Red Alga Gracilariopsis chorda.

In this study, we studied the bioactive peptides produced by thermolysin hydrolysis of a water-soluble protein (WSP) from the red alga Gracilariopsis chorda, whose major components are phycobiliproteins and Ribulose-1,5-bisphosphate carboxylase-oxygenase (RuBisCo). The results showed that WSP hydrolysate exhibited significantly higher ACE inhibitory activity (92% inhibition) compared to DPP-IV inhibitory activity and DPPH scavenging activity. The phycobiliproteins and RuBisCo of G. chorda contain a high proportion of hydrophobic (31.0-46.5%) and aromatic (5.1-46.5%) amino acid residues, which was considered suitable for the formation of peptides with strong ACE inhibitory activity. Therefore, we searched for peptides with strong ACE inhibitory activity and identified two novel peptides (IDHY and LVVER). Then, their interaction with human ACE was evaluated by molecular docking, and IDHY was found to be a promising inhibitor. In silico analysis was then performed on the structural factors affecting ACE inhibitory peptide release, using the predicted 3D structures of phycobiliproteins and RuBisCo. The results showed that most of the ACE inhibitory peptides are located in the highly solvent accessible α-helix. Therefore, it was suggested that G. chorda is a good source of bioactive peptides, especially ACE-inhibitory peptides.

Antihypertensive effect and underlying mechanism of tripeptide NCW on spontaneously hypertensive rats using metabolomics analysis.

Tripeptide NCW identified in our previous study displayed a strong ACE inhibitory activity, but whether it has any antihypertensive effect in vivo remains unknown. Thus, in this study, we aimed to investigate the protective effects of tripeptide NCW in spontaneously hypertensive rats (SHRs) and to further figure out the serum metabolic profiling variations due to its oral administration via UPLC-Q-TOF-MS/MS-based metabolomics analysis to clarify the underlying hypotensive mechanism. After three weeks of oral administration, the tripeptide NCW-treated group (NCW/SHR group, 80 mg per kg BW per d) showed significantly reduced systolic and diastolic blood pressure by 48.08 ± 3.84 mmHg and 48.92 ± 5.77 mmHg, respectively. Additionally, a total of 25 blood pressure-related metabolites were identified as being significantly changed in SHRs given tripeptide NCW after three weeks. These 25 metabolites might be biomarkers that indicated that the tripeptide NCW exhibits antihypertensive activity via regulating bile acid metabolism, lipid metabolism, amino acid metabolism, purinergic signaling, pantothenate and CoA biosynthesis, and the citrate cycle. Collectively, tripeptide NCW has a protective effect on SHRs associated with serum metabolite abnormalities.

Production of yeast hydrolysates by Bacillus subtilis derived enzymes and antihypertensive activity in spontaneously hypertensive rats

ABSTRACT Numerous studies have been carried out on antihypertensive peptides. However, the separation and purification were too costly, limiting their industrial application. The aim of this study was to produce antihypertensive yeast hydrolyzates (YH) with a simple and cost-saving procedure, coupling fermentation and enzymatic hydrolysis. Crude enzyme, exhibiting protease and β-glucanase activities, was generated from Bacillus subtilis Hu 528 and subsequently used to release and hydrolyze the intracellular proteins from dry yeast. YH exhibited strong ACE inhibitory activity, with IC50 value of 26.13 μg/mL, while antihypertensive properties were found on spontaneously hypertensive rats (SHRs) in short- and long-term administrations. YH could increase blood nitric oxide (NO) of SHRs. Moreover, 778 peptides were identified from YH by Nano LC-MS/MS and most of these peptides had ACE inhibitory potentials based on database search and alignment. This study indicated promising potential of YH as a source of ACE inhibitory peptides and potentially could be used in functional foods.

Characterization of Angiotensin-Converting Enzyme Inhibitory Activity of X-Hyp-Gly-Type Tripeptides: Importance of Collagen-Specific Prolyl Hydroxylation.

Hydroxyproline (Hyp) is a collagen-specific amino acid formed by post-translational hydroxylation of Pro residues. Various Hyp-containing oligopeptides are transported into the blood at high concentrations after oral ingestion of collagen hydrolysate. Here we investigated the angiotensin-converting enzyme (ACE) inhibitory activity of X-Hyp-Gly-type tripeptides. In an in vitro assay, ginger-degraded collagen hydrolysate enriched with X-Hyp-Gly-type tripeptides dose-dependently inhibited ACE and various synthetic X-Hyp-Gly-type tripeptides showed ACE-inhibitory activity. In particular, strong inhibition was observed for Leu-Hyp-Gly, Ile-Hyp-Gly, and Val-Hyp-Gly with IC50 values of 5.5, 9.4, and 12.8 μM, respectively. Surprisingly, substitution of Hyp with Pro dramatically decreased inhibitory activity of X-Hyp-Gly, indicating that Hyp is important for ACE inhibition. This finding was supported by molecular docking experiments using Leu-Hyp-Gly/Leu-Pro-Gly. We further demonstrated that prolyl hydroxylation significantly enhanced resistance to enzymatic degradation by incubation with mouse plasma. The strong ACE-inhibitory activity and high stability of X-Hyp-Gly-type tripeptides highlight their potential for hypertension control.

A Novel Antihypertensive Peptide Identified in Thermolysin-Digested Rice Bran.

Hypertension is a risk factor for arteriosclerosis. In this study, we investigate the antihypertensive effect of protease-digested rice bran in a spontaneously hypertension rat (SHR) model. We also purify a novel antihypertensive peptide from the digest. Thermolysin-digested rice bran (TRB) is administered to SHRs for 4 weeks, and systolic blood pressure (SBP) was measured weekly using the tail-cuff method. TRB shows an antihypertensive effect in a dose-dependent manner. TRB also reduces angiotensin I-converting enzyme (ACE) activity in lung tissue and serum troponin I levels. TRB is fractionated by HPLC and ACE-inhibitory activity in the HPLC fractions is measured. Peptides LRA and YY are identified from the two fractions with the strongest ACE-inhibitory activity. Amino acid sequence of these peptides are found in a vicilin-like seed storage protein, and identified in rice bran protein using the peptide mass fingerprint method. We confirm that LRA and YY are cleaved by thermolysin digestion of a model synthetic peptide. Orally administered LRA (0.25mgkg-1 ) or YY (0.5mgkg-1 ) lowers the SBP of SHRs at 4h after administration. We identify a novel, orally active antihypertensive peptide, LRA from the digest of rice bran protein.

Phytochemical composition, antioxidant capacity and ACE-inhibitory activity of China-grown radish seeds

The seeds of nine China-grown radish cultivars were analyzed for their phytochemical composition, antioxidant properties and ACE-inhibitory activity. Radish seeds contained 36.87–43.06% (w/w) oils, whereas 64.55–69.26% of the fatty acids were monounsaturated and 20.33–25.11% were polyunsaturated. The levels of δ- tocopherol (552.24–670.31 μg/g seed oils) and lutein (4.82–8.95 μg/g seed oils) differed in cultivars. The nine cultivars were varied in total phenolics, flavonoids, and free phenolic acids, but not in proanthocyanidins. Seed extracts of Hybrid #63, Tou Xin Hong, and Hybrid #72 showed stronger DPPH radical scavenging capacity, ORAC, and FRAP than others (p<0.05). The Yanzhi #2 extracts exhibited a strong ACE-inhibitory activity, which was positively correlated with vanillic acid contents (r = 0.890, p = 0.001). It provides evidence on developing value-added utilization of radish seeds or seed fractions such as oil and flour as nutraceuticals or functional food ingredients.

ACE- inhibitory and radical scavenging activities of bioactive peptides obtained from camel milk casein hydrolysis with proteinase K

The aim of this study was to evaluate the effects of enzymatic hydrolysis of camel whole casein on their antioxidant and angiotensin-converting enzyme (ACE)-inhibitory properties. Whole camel casein was hydrolyzed by proteinase K (PK), and the hydrolysates were fractionized by ultrafiltration membranes into three fractions. Semi-preparative reversed-phase high-performance liquid chromatography (RP-HPLC) was used to differentiate the mixture of peptides in the 3 kDa permeate fractions. A fraction (F4) with potentials of ACE-inhibitory activity (IC50 = 73 μg.mL−1) and radical scavenging activity (IC50 = 6.8 μg.mL−1) was selected for further purification and fractionation. The fraction F4C obtained from a second step purification of F4 showed strong ACE-inhibitory activity (IC50 = 36 μg.mL−1) as well as radical scavenging activity (IC50 = 3.3 μg.mL−1). The results of this study suggest that whole camel casein can be considered as a promising source for the production of peptides with potential of ACE-inhibitory and antioxidant activities.

In vitro and in vivo antihypertensive activity of palm kernel cake protein hydrolysates: Sequencing and characterization of potent bioactive peptides

This study was aimed to generate a valuable protein hydrolysate and bioactive peptides with strong ACE-inhibitory activity in vitro and in vivo from palm kernel cake (PKC) protein. PKC protein was independently hydrolyzed by seven different proteases to produce PKC protein hydrolysates. Among those investigated, papain-produced hydrolysate revealed the highest ACE-inhibitory activity (70.9%). When normotensive rats induced with hypertension were fed the hydrolysate at a dose of 75mg/kg body weight, their blood pressures stabilized considerably. Fractionation of the protein hydrolysate using RP-HPLC revealed a direct relationship between hydrophobicity and ACE-inhibitory activity. The fractions with relatively higher ACE-inhibitory activity were further fractionated by isoelectric focusing, out of which fractions having neutral and basic charges showing higher ACE-inhibitory activities (77% and 75%, respectively). Nine peptide sequences were identified by Q-TOF mass spectrometry, and their respective ACE-inhibitory activities evaluated. The peptide sequences YLLLK, YGIKVGYAIP, and LPWRPATNVF showed ACE-inhibitory activities of 100%; however, the best IC50 values were observed for YGIKVGYAIP, GIFE and LPWRPATNVF at 1μM, 3μM and 20μM, respectively.

Antioxidant, ACE-Inhibitory, and Antimicrobial Activities of Peptide Fractions Obtained From Dried Giant Squid Tunics

ABSTRACTSquid tunics were divided in two batches: freeze-dried and air-dried. Dried squid tunics were directly hydrolyzed with pepsin, Alcalase, and Esperase. Freeze-dried tunics showed better aptitude for hydrolysis than air-dried tunics. Pepsin showed the lowest efficiency in protein breakdown and gave hydrolysates with low antioxidant activity, whereas Alcalase and Esperase peptide fractions showed strong radical scavenging ability, ACE-inhibitory activity, and noticeable antimicrobial properties. B. cereus, B. coagulans, and D. hansenii were found to be the most sensitive bacteria. Dried squid tunics proved to be an alternative to a previously extracted gelatin for obtaining bioactive peptides.

Selected adjunct cultures remarkably increase the content of bioactive peptides in Bulgarian white brined cheese

Some lactic acid bacteria strains in milk media are capable of releasing bioactive peptides. In this study, we evaluated the angiotensin-converting enzyme (ACE)inhibitory activity of 180 lactic acid bacteria and selected several Lactobacillus helveticus, L. delbrueckii subsp. bulgaricus and L. casei strains that demonstrated strong ACE-inhibitory activity. The aim was to carry out a molecular study on the bioactive peptides released by the strains with the best ACE-inhibitory properties and by the strains demonstrating a calcium-binding effect. To the best of our knowledge, this is the first study of bioactive peptides in Bulgarian white cheese. Peptides with the strongest ACE-inhibitory activity were purified and sequenced. The strains were assessed for production of peptides with calcium-binding properties. These peptides were isolated, purified and sequenced. Two strains releasing bioactive peptides with the strongest ACE-inhibitory and calcium-binding activities were selected for development of cheese starters. The strain with the best ACE-inhibitory activity was L. helveticus A1, which releases the peptide Ala-Leu-Pro-Met as a main contributor to the ACE inhibition. The strain with the best calcium-binding activity was L. casei C3 releasing the peptide SpLSpSpSpE (fraction 15–20 of ß-casein) as a main contributor to calcium binding. After pilot production of cheeses with the developed starters, the ACE-inhibitory and calcium-binding effects were confirmed during the cheese ripening. The addition of the two selected adjunct cultures led to increased production of bioactive peptides in the cheese. In this way, it is possible to increase the functional properties of Bulgarian white brined cheese.

Novel angiotensin I-converting enzyme inhibitory peptide derived from bovine casein

Bovine lactic casein was hydrolysed using a combination of three enzymes, namely, subtilisin, bacillolysin, and trypsin, and the resulting preparation was coined CH-3. CH-3 showed angiotensin I-converting enzyme (ACE)-inhibitory activity (IC50: 74μg/mL). A single oral administration of CH-3 led to a transient but significant decrease in the systolic blood pressure (SBP) of spontaneously hypertensive rats (SHRs), while daily oral administration of CH-3 for 28 consecutive days led to a lower rate of SBP increase. The CH-3 preparation was then fractionated and the αS2-casein-derived tripeptide Met-Lys-Pro (or MKP) was identified as a novel peptide with strong ACE-inhibitory activity (IC50=0.12μg/mL, 0.3μM). The MKP peptide constituted only 0.053% of CH-3 but its activity was accounted for 33% of the total ACE-inhibitory activity of CH-3. In addition, a single oral administration of MKP also led to a transient but significant decrease in the SBP of SHRs.

Physicochemical properties of silkworm larvae protein isolate and gastrointestinal hydrolysate bioactivities

The objectives of this study were to investigate the amino acid composition and thermal properties of silkworm larvae protein isolate (SLPI) and to evaluate the in vitro angiotensin-converting enzyme (ACE) inhibitory and antioxidant activities of its hydrolysate prepared with gastrointestinal enzymes. The results showed that, SLPI was a high quality protein source with a well-balanced composition of essential amino acids, which was especially rich in glutamic acid (13.79 g/100 g protein), aspartic acid (10.44 g/100 g protein), leucine (8.68 g/100 g protein), lysine (8.01 g/100 g protein) and arginine (6.59 g/100 g protein). In additon, three endothermic denaturation transitions were observed in DSC thermograms of SLPI. The maximum transition peak occurred in the third thermal transition, which denaturation temperature (T d ), peak temperature of denaturation (T p ) and enthalpy change (ΔH) were 76.95°C, 80.42°C and 783.75 J/g, respectively. SLPI hydrolysate exhibited strong ACE-inhibitory activity (IC 50 =8.3 μg/ml) and relatively higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (IC 50 =57.91 μg/ml) and ferrous ions chelating capacity (IC 50 =2.03 mg/ml). Moreover, the hydrolysate showed notable reducing power. It was concluded that, SLPI might be considered as a multifunctional ingredients for functional foods with protein supplements, ACE-inhibitory and antioxidant activity. Key words : Silkworm larvae protein isolates (SLPI), amino acid composition, thermal properties, gastrointestinal enzymes, hydrolysis, ACE inhibition, antioxidant.

Production of angiotensin-I-converting enzyme (ACE) inhibitory activity in milk fermented with probiotic strains: Effects of calcium, pH and peptides on the ACE-inhibitory activity

Recently, probiotic fermented milk products have raised interest regarding their potential anti-hypertensive activity mainly due to the production of angiotensin-I-converting enzyme (ACE) inhibitory peptides. Ionic calcium released upon milk acidification during fermentation is also known to exert hypotensive activity. Thus, the main aim of this study was to screen probiotic strains for their ability to induce ACE-inhibitory activity upon fermentation of milk. The relationship of ACE-inhibitory activity percentage (ACEi%) with cell growth, pH, degree of hydrolysis and the concentration of ionic calcium released during the fermentation was also investigated. Compared with other lactic acid bacteria, Lactobacillus casei YIT 9029 and Bifidobacterium bifidum MF 20/5 were able to induce strong ACE-inhibitory activity. Furthermore, it was found that the ionic calcium released during milk fermentation could contribute to the ACE-inhibitory activity. These findings will contribute to the development of new probiotic dairy products with anti-hypertensive activity.

Angiotensin-I Converting Enzyme Inhibitory Activity of Hydrolysates from Oat (Avena sativa) Proteins byIn SilicoandIn VitroAnalyses

The potential for producing antihypertensive peptides from oat proteins through enzymatic hydrolysis was assessed in silico and confirmed in vitro. Thermolysin (EC 3.4.24.27) was predicted using BIOPEP database as the enzyme that would theoretically produce the most angiotensin I converting enzyme (ACE) inhibitory peptides from oat. Experimental evidence confirmed that strong ACE-inhibitory activity was produced under various hydrolysis conditions. Hydrolysates produced under high enzyme-to-substrate ratio (3%) short time (20 min) (HEST) and low enzyme-to-substrate ratio (0.1%) long time (120 min) (LELT) conditions had IC(50) values of 30 and 50 microg/mL, respectively. After simulated gastrointestinal digestion, the IC(50) of the HEST hydrolysate was 35 microg/mL whereas the IC(50) of the LELT hydrolysate was higher at 85 microg/mL. Ultrafiltration revealed that potent ACE-inhibitory peptides had molecular weights below 3 kDa. This study demonstrates the usefulness of in silico analysis to select enzymes for hydrolysis of proteins not previously examined as sources of bioactive peptides.

食品タンパク質由来機能性ペプチドによる血圧降下作用 イワシペプチド（Ｖａｌ‐Ｔｙｒ）による降圧食品の開発を中心として

The procedures for preparing a food material with antihypertensive efficacy from sardine muscle have been reviewed. Hydrolysis of sardine muscle by pepsin yielded angiotensin I-converting enzyme (ACE)-inhibitory peptides. Further studies aimed at preparing a hydrolyzate with potent ACE-inhibitory activity as well as having good flavor were carried out using Bacillus licheniformis alkaline protease. After 17h of hydrolysis of 0.3wt% sardine protein, the 10wt% ethanol fraction obtained with ODS resin showed some excellent properties, including strong ACE-inhibitory activity (IC50=0.015mg protein/mL), high digestive resistance, no bitterness, and no antigenicity. In addition, this fraction was confirmed to have a significant in vivo depressor effect in mildly hypertensive volunteers (n=29), who showed a 9.3mmHg reduction in systolic blood pressure and 5.2mmHg reduction in diastolic blood pressure after 4 weeks of oral administration of this peptide drink (4g of the ODS fraction/200mL/day).