Against Angiotensin Converting Enzyme Research Articles

<i>In Silico</i> Computational Analysis of <i>Citrus aurantium</i> of <i>Thurunji manapagu</i> in Inhibiting the Receptor Target of Angiotensin-converting Enzyme Against <i>Uratha Pitha Vatham</i> (Hypertension)

Citrus aurantium (Thurunji) is a tree cultivated in various parts of the world. The fruit pulp is used to make juices, marmalade and pickles. It is commonly used by tribes to treat digestive disorders, constipation, heaviness in the chest, prolapse of the uterus, anorexia, chest pain, cold, and cough. In the Siddha system of medicine, Citrus aurantium fruit pulp is used to prepare a formulation, syrup in consistency named Thurunji manapaagu indicated for diseases due to deranged pitha humor. According to the Siddha system of medicine Hypertension termed Uratha Pitha Vatham is an ailment that occurs due to an elevated pitham. Considering the facts an attempt of in silico docking study was done with the selected phytochemicals such as Linalool, Apigenin, Ichangin, Kaempferol, Luteolin, Limonin, Limonene, Myrcene, Diosmetin and Tangeretin of Citrus aurantium against Angiotensin Converting Enzyme (ACE) and the results are detailed in this article.

Anti-hypertensive effect of Siddha formulation Imbural Vadagam against Human angiotensin converting enzyme using In-Silico model

Background: Siddha Medicine is emerging as the treatment of choice for various diseases. Hypertension is one among the comorbidities which plays a major role leading to stroke, cardiovascular diseases and renal failure. Objective: To perform the In Silico computational studies of phytocomponents of Imbural vadagam and to evaluate its anti-hypertensive potential. Methods: Auto dock program was used for the molecular docking studies against Angiotensin Converting Enzyme(ACE). Results: Asperulosidic acid, 6α-Hydroxygeniposide, Piperic acid, Piperine, Apigenin, Orientin and Vitexin that exist in the siddha drug Imbural vadagam exhibit remarkable binding against the target Angiotensin converting enzyme. Conclusion: It can be that these phytocomponents exhibit remarkable antihypertensive activity.

Phytochemical Composition and Inhibitory Activities of Hibiscus sabdariffa and Cucumis sativus Infusions Against Angiotensin-Converting Enzyme

Hibiscus sabdariffa and Cucumis sativus are often used in ethnomedicinal practice for treating several health conditions, including hypertension. The present study aimed to investigate the in vitro inhibitory activities of H. sabdariffa and C. sativus against angiotensin-converting enzyme (ACE) and their phytochemical properties directly from their infusions. Each infusion was prepared with a concentration of 10, 20, and 30 grams of plant material in 300 ml of hot distilled water. Combinations of both plants were also prepared in 1:1, 2:1, and 1:2 ratios. The inhibitory activities were determined by the colorimetric method. The results showed that the highest inhibition rates of H. sabdariffa and C. sativus infusions were 88.741±0.001% and 92.180±0.001%, respectively. Meanwhile, the highest inhibition rate of the combination infusion was obtained from the ratio of H. sabdariffa: C. sativus (1:2), which was 96.062±0.001%, although this result was still below the inhibitory activity of Captopril (97.393±0.001%). The phytochemical screening results indicated that H. sabdariffa infusions contain saponins and tannins, and C. sativus infusions contain alkaloids, saponins, and terpenoids. This study concluded that the infusion with the ratio of H. sabdariffa: C. sativus (1:2) demonstrated the strongest inhibitory activity against ACE and, therefore, could potentially be utilized as a functional drink for managing hypertension.

Prediction of Anti-Hypertensive Potential of Siddha Formulation – Sagalanoi Chooranam against Angiotensin-Converting Enzyme (ACE): A Computational Approach

Prediction of Anti-Hypertensive Potential of Siddha Formulation – Sagalanoi Chooranam against Angiotensin-Converting Enzyme (ACE): A Computational Approach

Novel angiotensin-converting enzyme and pancreatic lipase oligopeptide inhibitors from fermented rice bran.

This study determined the inhibitory activity of oligopeptides against angiotensin-converting enzyme (ACE) and pancreatic lipase through in vitro tests, molecular docking, and enzyme inhibition. The results showed that the IC50 of GLLGY, HWP, and VYGF for ACE inhibition was 1 mg/mL, and the IC50 of HWP for pancreatic lipase was 3.95 mg/mL. Molecular docking revealed that the binding energies between GLLGY, HWP, and VYGF and ACE were –9.0, –8.4, and –9.2 kcal/mol, respectively. The binding free energy between HWP and pancreatic lipase was –7.3 kcal/mol. GLLGY, HWP, and VYGF inhibited ACE compentitively. HWP inhibited pancreatic lipase through non-competition. in vitro simulated gastrointestinal digestion, the three oligopeptides still had inhibitory activity and low toxicity. The results revealed that the peptides GLLGY, HWP, and VYGF may be suitable candidates for further research on ACE inhibition, and HWP may be a suitable candidate for studying pancreatic lipase inhibition.

Biological activity of peptides isolated from feather keratin waste through microbial and enzymatic hydrolysis

BackgroundA major portion of poultry feather waste is constituted by keratin, which is recalcitrant to degradation by common proteases. Feather waste contributes to a significant volume of biowaste load to the environment. Valorization of these wastes into various products has been attempted by many researchers. The present study aimed to produce peptides (molecular weight < 10 kDa) from feather waste by the action of keratinolytic bacteria or keratinase enzyme and to screen the peptides for pharmaceutical and therapeutic properties. The feathers were subjected to hydrolysis by using locally isolated keratinolytic microorganisms, namely Streptomyces tanashiensis-RCM-SSR-6, Bacillus sp. RCM-SSR-102, and purified keratinase enzyme KER-102. ResultsThe feather keratin hydrolysate obtained by hydrolysis with different bacterial species/enzymes showed different protein profiles in SDS-PAGE. As indicated by Fourier Transform Infrared Spectroscopy (FTIR) analysis, a difference was observed in the composition of α-helix and β-sheet in the peptides produced by different microbial/enzymatic methods. The peptides were screened for antioxidant potential, antityrosinase property, and inhibitory activity against angiotensin-converting enzyme (ACE), lipoxygenase, and xanthine oxidase. The peptides showed promising results in all the assays, except peptide-102 that did not show ACE inhibitory activity. Interestingly, the crude peptide-6 (4.06 µg/mL) and peptide-102 (10.21 µg/mL) showed a lower EC50 value than the standard Kojic acid (27.04 µg/mL) in antityrosinase assay. ConclusionsDegradation of chicken feather waste with microbial or enzymatic method is an eco-friendly approach to yield diverse bioactive peptides. Hence, the present study established that feather keratin could be a potential source of many health-beneficial peptides.How to cite: Kshetri P, Singh PL, Chanu SB, et al. Biological activity of peptides isolated from feather keratin waste through microbial and enzymatic hydrolysis. Electron J Biotechnol 2022;60. https://doi.org/10.1016/j.ejbt.2022.08.001.

Antihypertensive and Cardioprotective Property of Mimosa pudica Using Zebra Fish

Pharmacognosy Research,2022,14,3,333-337.DOI:10.5530/pres.14.3.49Published:July 2022Type:Original ArticleAuthors:Santhosh Kondajji Hanumanthappa, Joy Hoskeri Harris, Nivedita Pujari Sudhakar, Priyanka Ashoka, and Manjunatha Hanumanthappa Author(s) affiliations:Santhosh Kondajji Hanumanthappa1, Joy Hoskeri Harris2, Nivedita Pujari Sudhakar2, Priyanka Ashoka1, Manjunatha Hanumanthappa1,3* 1Department of Biotechnology and Bioinformatics, Jnanasahyadri, Kuvempu University, Shankaraghatta, Shivamogga, Karnataka, INDIA. 2Department of Bioinformatics, Karnataka State Akkamahadevi Women’s University, Torvi, Vijayapura, Karnataka, INDIA. 3Department of Biochemistry, Jnana Bharathi Campus, Bangalore University, Bangalore, Karnataka, INDIA. Abstract:Background: Increase in blood pressure is generally termed as hypertension which is one of the common causes of cardiovascular diseases. Despite the several treatment methods, hypertension stands to be the major concern in developing countries. Angiotensin converting enzyme is one of the key contributors in regulating blood pressure where improper activation of angiotensisn leads to hypertension. Mimosa pudica plant has been reported to exhibit several therapeutic properties and thus the current study was focused on evaluating antihypertensive property of phytochemicals found in the Mimosa pudica extract. Materials and Methods: Methanol extract of Mimosa pudica was examined for presence of potential phytochemicals by GC-MS and molecular docking studies were carried out using Autodock 4.2. Results: 07 phytochemicals were identified in the methanol extract of Mimosa pudica. Further molecular docking studies against angiotensin converting enzyme (ACE) was carried out and among the list of test compounds 9,12-octadecadienoic acid showed least binding energy with -6.6 kJ. Conclusion: Compounds selected as phytochemicals of Mimosa pudica from methanol extract of Mimosa pudica, specially 9,12-octadecadienoic acid considered for further evaluation of antihypertensive and cardioprotective activity. Keywords:Angiotensin converting enzyme, Antihypertensive activity, Antihypertensive and cardioprotective activity, Methanol extract, Mimosa pudicaView:PDF (270.04 KB)

Semi-Industrial Production of a DPP-IV and ACE Inhibitory Peptide Fraction from Whey Protein Concentrate Hydrolysate by Electrodialysis with Ultrafiltration Membrane.

The separation by electrodialysis with ultrafiltration membranes (EDUF), at a semi-industrial scale, of a new whey protein hydrolysate obtained from a whey protein concentrate was assessed. After 6 h of treatment, more than 9 g of peptides were recovered in the peptide recovery fraction, for a recovery yield of 5.46 ± 0.56% and containing 18 major components. Among these components, positively charged peptides, such as ALPMHIR + PHMIR, LIVTQTMK and TKIPAVF, were present, and their relative abundances increased by nearly 1.25 X and up to 7.55 X. The presence of these peptides may be promising, as ALPMHIR has a strong activity against angiotensin-converting enzyme (ACE), and LIVTQTMK has structural properties that could interfere with dipeptidyl peptidase-IV (DPP-IV). Many neutral peptides were also recovered alongside those. Nevertheless, the inhibitory activity against DPP-IV and ACE increased from 2 X and 4 X, respectively, in the peptide recovery fraction compared to the initial hydrolysate, due to the improved content in bioactive peptides. Thus, this new hydrolysate is well-suited for the large-scale production of a peptide fraction with high bioactivities. Furthermore, what was achieved in this work came close to what could be achieved for the industrial production of a bioactive peptide fraction from whey proteins.

Influence of Sonication and Taraxacum Officinale Addition on the Antioxidant and Anti-ACE Activity of Protein Extracts from Sous Vide Beef Marinated with Sour Milk and after In Vitro Digestion

The present study assessed the effect of pretreating beef as a raw material for sous vide steak preparation. The pretreatment involved maceration of a batch of meat in sour milk with the simultaneous use of ultrasound (250 or 500 W) as well as the addition of Taraxacum officinale. The biological activity profile of the peptides was assessed in terms of their antioxidant activity and inhibiting activity against angiotensin-converting enzyme (ACE). Changes in the biological activity of peptides under the influence of hydrolysis by gastrointestinal enzymes, i.e., pepsin and pancreatin, were also considered. There was no significant effect of T. officinale addition and sonication of beef batches on the protein content (except for lot S6, after sonication at 500 W as acoustic power and with the addition of dandelion). It was observed that the interaction of maceration in sour milk with simultaneous ultrasound treatment as the initial production step of sous vide beef steak generates the formation of peptides with antioxidant properties. Moreover, peptide formation can be further enhanced by adding dandelion (based on the results of antiradical and chelating activity tests). In addition, the progression of hydrolysis under the influence of gastrointestinal enzymes promotes the release of peptides with antioxidant and anti-ACE activity.

Lactic Acid Bacteria from Apis dorsata Hive Possessed Probiotic and Angiotensin-Converting Enzyme Inhibitor Activity

One source of bacteria that has not been widely explored is lactic acid bacteria originating from honeycomb (hive). Timor Island has a wealth of giant honey bees (Apis dorsata). Lactic acid bacteria from the Apis dorsata hive in Timor Island need to be investigated to obtain probiotic candidates with specific functional properties. Lactic acid bacteria were isolated from honeycomb by using de Mann, Rogosa, and Sharpe agar supplemented with 1% of CaCO3. Bacterial isolates that formed clear zones and were Gram-positive and catalase-negative were determined as lactic acid bacteria. The probiotic candidates are isolates that are resistant to bile salts and low pH; susceptible to antibiotics; are able to aggregate, autoaggregate, and coaggregate; and have antibacterial activities. Isolate MC7 was selected as a probiotic candidate and had inhibitory activity against angiotensin-converting enzyme (ACE) with IC50 263,098 ppm. Isolate MC7 showed weak inhibition against ɑ-glucosidase activity. Molecular identification based on 16S rRNA gene showed that MC7 isolate was closely related to Lactobacillus rhamnosus with 100% similarity. Therefore, isolate MC7 was recommended as a probiotic candidate with a functional property as an inhibitor of ACE.

Inhibition of angiotensin-converting enzyme by selenoneine

Selenoneine is a selenium-containing compound that exhibits strong radical-scavenging activity. Here we present a novel function of selenium in which selenoneine exhibits inhibitory activity against angiotensin-converting enzyme (ACE). ACE activity was strongly inhibited by selenoneine as compared to a typical peptide that decreases blood pressure in vitro. Kinetics analysis suggested that selenoneine inhibits ACE by competitive inhibition via the binding of selenoneine to zinc in the active center of ACE.

Production of bioactive oligopeptide hydrolyzed by protease derived from aerial microalga Vischeria helvetica

This study focused on a culture system of aerial microalgae with the decomposition of casein protein for obtaining bioactive compounds such as peptides with inhibitory activity against angiotensin-converting enzyme (ACE). The aerial microalga Vischeria helvetica exhibited growth in Bold’s basal medium supplemented with casein protein as nitrogen source. The algal cells secreted protease and amino oxidase into the medium, and ammonium ions as a nitrogen source was produced by the conjugated-enzyme reaction. Furthermore, a bioactive peptide with ACE-inhibitory activity was efficiently produced from casein protein by the proteases secreted under light conditions. The results presented will facilitate the development of production systems for useful materials from photosynthetic microorganisms and casein protein in a culture medium.

VIRTUAL SCREENING OF HETEROCYCLIC COMPOUNDS AGAINST ANGIOTENSIN-CONVERTING ENZYME FOR POTENTIAL ANTIHYPERTENSIVE INHIBITORS

Objective: The objective of this study was to investigate the antihypertensive activity of heterocyclic compounds against angiotensin-converting enzyme (ACE) through molecular docking studies.&#x0D; Methods: The X-ray crystal three-dimensional (3D) structure of human ACE complexed with lisinopril (PDB ID: 1O86) was retrieved from protein databank. The two-dimensional structures of 10 selected heterocyclic compounds were drawn in ACD-Chemsketch and converted into 3D structures. The 3D structures of compounds were virtually screened in the binding pockets of ACE using FlexX docking program. Further, the chemical entities revealing the molecular electronic structures of the best docked compound (Compound-4) were explored through density functional theory studies.&#x0D; Results: The Compound-4 showed the highest docking score of −26.6290 kJ/mol with ACE. The Hbond and non-bonded interactions are favored by phenylalanine, leucine, and arginine. The energy gap of 1.60 eV between highest occupied molecular orbital and lowest unoccupied molecular orbitals explained the presence of strong electron-acceptor group. Furthermore, the molecular electrostatic potential studies clearly envisaged the requirement of electropositive and electronegative groups are crucial for the ACE inhibitor activities.&#x0D; Conclusion: The identification of good ACE inhibitors requires the understanding of the current ACE inhibitors. Thus, the docking interactions of Compound-4 and its molecular electronic structure significantly imply its potential as antihypertensive agent. However, further clinical studies are required to ascertain its potential toxic effects.

Macrocyclic lactones from seafood Amphioctopus neglectus: Newly described natural leads to attenuate angiotensin-II induced cardiac hypertrophy

Amphioctopus neglectus (Family: Octopodidae) is recognised as culinary delicacy in many cultures and a common sea food item on the Mediterranean and Asian coasts. Bioassay-directed fractionation of ethyl acetate/methanol extract of A. neglectus ensued in the characterisation of four previously undescribed macrocyclic lactones (1-4). These compounds exhibited potential radical-scavenging capacities (IC50 0.95–1.73 mM) along with anti-hypertensive activities (IC50 1.12–2.34 mM) against angiotensin converting enzyme (ACE). The optimum binding affinity of compound 2 (−9.84 kcal mol−1) bearing furo[1,4,8]trioxacyclohexadecine-12,19-dione moiety with ACE, along with its permissible hydrophobic-hydrophilic balance, manifested towards its greater anti-hypertensive activity compared to other analogues. The compound 2, with lesser values of the inhibitory constant (Ki = 1.0 mM) towards ACE, was found to bind more effectively to the enzyme in a non-competitive manner, and could describe the greater inhibitory ramifications than those displayed by other compounds (Ki >1.1 mM). The ex-vivo studies revealed that compound 2 imparted protective effects against angiotensin-II induced cardiac hypertrophy at 25 μg mL−1 on H9C2 cell lines, wherein about 34 percent decrease in cell area with increase in viability could be attributed to anti-hypertrophic effects of the compound administrated. These results confirmed that the protective effect of the isolated macrocyclic lactones is mediated by enhancement of anti-oxidant defense systems, which subsequently attenuates the hypertensive related disorders.

Nutritional and functional properties of fishmeal produced from fresh by-products of cod (Gadus morhua L.) and saithe (Pollachius virens).

Fresh by-products of whitefish such as cod and saithe is processed to fishmeal (FM) on-board seagoing Norwegian trawlers. The aim of this study was to document the properties of whitefish FM (WFM) protein with respect to, physicochemical and bioactive properties. Analysis of the proximate composition of representative seasonal WFM batches show that the production is robust without much variance. The mean protein (61.9 ± 1.2), fat (8.9 ± 1.1%), moisture (5 ± 1.2%) and ash content (22.4 ± 0.8%), reflect the use of lean and bony raw-material. The WFM has a low content of free amino acids (0.7%) and biogenic amines (< 1000 mg/kg) that confirm the high quality and freshness of the raw material. Amino-acid analysis identified the presence of all nutritionally essential amino acids. The WFM physicochemical properties was comparable to soy-bean meal (SBM) by analysis of solubility, water-holding capacity (WHC), the emulsion stability (ES). Proteolytic degradation of the WFM was used to demonstrate the presence of bioactive peptides with inhibiting activity against angiotensin-converting enzyme (ACE) activity, in vitro. Taken together, WFM produced from fresh by-products is an excellent protein source with attributes of interest beyond the aquafeed-market.

Synthesis and characterization of novel astragalin galactosides using β-galactosidase from Bacillus circulans.

Astragalin (kaempferol-3-O-β-d-glucopyranoside, Ast) is a kind of flavonoid known to have anti-oxidant, anti-HIV, anti-allergic, and anti-inflammatory effects. It has low solubility in water. In this study, novel astragalin galactosides (Ast-Gals) were synthesized using β-galactosidase from Bacillus circulans and reaction conditions were optimized to increase the conversion yield of astragallin. Purified Ast-Gal1 (11.6% of Ast used, w/w) and Ast-Gal2 (6.7% of Ast used, w/w) were obtained by medium pressure chromatography (MPLC) with silica C18 column and open column packed with Sephadex LH-20. The structures of Ast-Gal1 and Ast-Gal2 were identified by nuclear magnetic resonance (NMR) to be kaempferol-3-O-β-d-glucopyranosyl-(1→6)-β-d-galactopyranoside and kaempferol-3-O-β-d-glucopyranosyl-(1→6)-β-d-galactopyranosyl-(1→4)-β-d-galactopyranoside, respectively. The water solubility of Ast, Ast-Gal1, and Ast-Gal2 were 28.2±1.2mg/L, 38,300±3.5mg/L, and 38,800±2.8mg/L, respectively. The SC50 value (the concentration required to scavenge 50% of the ABTS+) of Ast, Ast-Gal1, and Ast-Gal2 were 5.1±1.6μM, 6.5±0.4μM, and 4.9±1.1μM, respectively. The IC50 values (the half maximal inhibitory concentration) of Ast, Ast-Gal1, and Ast-Gal2 against angiotensin converting enzyme (ACE) were 171.0±1.2μM, 186.0μM, and 139.0±0.2μM, respectively.

Antihypertensive properties of tilapia (Oreochromis spp.) frame and skin enzymatic protein hydrolysates

ABSTRACTProteins from tilapia frame and skin can potentially be precursors of antihypertensive peptides according to the result of BIOPEP analyses. The aim was to generate peptides with inhibitory effects against angiotensin-converting enzyme (ACE) and renin from tilapia frame and skin protein isolates (FPI and SPI). The most active hydrolysate was then tested for blood pressure-lowering ability in spontaneously hypertensive rats (SHRs). Tilapia frame and skin protein hydrolysates (FPHs and SPHs) were respectively produced from FPI and SPI hydrolysis using pepsin, papain, or bromelain. The ACE-inhibitory activities of tilapia protein hydrolysates with varying degree of hydrolysis (DH) were evaluated. In order to enhance the activity, the hydrolysate was fractionated into four fractions (<1 kDa, 1–3 kDa, 3–5 kDa, and 5–10 kDa) and the one with the greatest ability to inhibit in vitro ACE and renin activities was subjected to oral administration (100 mg/kg body weight) to SHRs. Systolic and diastolic blood pressure (SBP and DBP), mean arterial pressure (MAP), and heart rates (HR) were subsequently measured within 24 h. The pepsin-hydrolyzed FPH (FPHPe) with the highest DH (23%) possessed the strongest ACE-inhibitory activity (IC50: 0.57 mg/mL). Its <1 kDa ultrafiltration fraction (FPHPe1) suppressed both ACE (IC50: 0.41 mg/mL) and renin activities more effectively than larger peptides. In addition, FPHPe1 significantly (p < 0.05) reduced SBP (maximum −33 mmHg), DBP (maximum −24 mmHg), MAP (maximum −28 mmHg), and HR (maximum −58 beats) in SHRs. FPHPe1 showed both in vitro and in vivo antihypertensive effects, which suggest tilapia processing coproducts may be valuable protein raw materials for producing antihypertensive peptides.

Inhibitory properties of bambara groundnut protein hydrolysate and peptide fractions against angiotensin-converting enzymes, renin and free radicals.

An increased rate of high blood pressure has led to critical human hypertensive conditions in most nations. In the present study, bambara protein hydrolysates (BPHs) obtained using three different proteases (alcalase, trypsin and pepsin) and their peptide fractions (molecular weight: 10, 5, 3 and 1 kDa) were investigated for antihypertensive and antioxidant activities. Alcalase hydrolysate contained the highest amount of low molecular weight (LMW) peptides compared to pepsin and trypsin hydrolysates. LMW peptides fractions (<1 kDa) exhibited the highest inhibitory activity against angiotensin-converting enzyme (ACE) for all the enzymes hydrolysates. For renin inhibition, alcalase hydrolysate showed the highest inhibition at 59% compared to other hydrolysates and their corresponding membrane fractions. The antioxidant power of bambara protein hydrolysates and peptide fractions was evaluated through the inhibition of linoleic acid peroxidation and ABTS scavenging activity. Among the hydrolysates, alcalase exhibited the highest inhibition of linoleic acid oxidation. Furthermore, all BPHs were able to scavenge ABTS•+ to a three-fold greater extent compared to the isolate. BPH and LMW peptide fractions could potentially serve as useful ingredients in the formulation of functional foods and nutraceuticals against high blood pressure and oxidative stress. © 2016 Society of Chemical Industry.

Top-down Targeted Metabolomics Reveals a Sulfur-Containing Metabolite with Inhibitory Activity against Angiotensin-Converting Enzyme in Asparagus officinalis.

The discovery of bioactive natural compounds containing sulfur, which is crucial for inhibitory activity against angiotensin-converting enzyme (ACE), is a challenging task in metabolomics. Herein, a new S-containing metabolite, asparaptine (1), was discovered in the spears of Asparagus officinalis by targeted metabolomics using mass spectrometry for S-containing metabolites. The contribution ratio (2.2%) to the IC50 value in the crude extract showed that asparaptine (1) is a new ACE inhibitor.

Kinetics of the inhibition of renin and angiotensin I-converting enzyme by cod (Gadus morhua) protein hydrolysates and their antihypertensive effects in spontaneously hypertensive rats

BackgroundCod muscle has a balanced protein profile that contains potentially bioactive amino acid sequences. However, there is limited information on release of these peptides from the parent proteins and their ability to modulate mammalian blood pressure.ObjectiveThe aim of this study was to generate cod antihypertensive peptides with potent in vitro inhibitory effects against angiotensin-converting enzyme (ACE) and renin. The most active peptides were then tested for systolic blood pressure (SBP)-reducing ability in spontaneously hypertensive rats (SHRs).DesignCod protein hydrolysate (CPH) was produced by subjecting the muscle proteins to proteolysis first by pepsin and followed by trypsin+chymotrypsin combination. In order to enhance peptide activity, the CPH was subjected to reverse-phase (RP)-HPLC separation to yield four fractions (CF1, CF2, CF3, and CF4). The CPH and RP-HPLC fractions were each tested at 1 mg/mL for ability to inhibit in vitro ACE and renin activities. CPH and the most active RP-HPLC fraction (CF3) were then used for enzyme inhibition kinetics assays followed by oral administration (200 and 30 mg/kg body weight for CPH and CF3, respectively) to SHRs and SBP measurements within 24 h.ResultsThe CPH, CF3, and CF4 had similar ACE-inhibitory activities of 84, 85, and 87%, which were significantly (p<0.05) higher than the values for CF1 (69%) and CF2 (79%). Conversely, the CF3 had the highest (63%) renin-inhibitory activity (p<0.05) when compared to CPH (43%), CF1 (15%), and CF4 (44%). CPH and CF3 exhibited uncompetitive mode of ACE inhibition, whereas renin inhibition was non-competitive. Even at a 6.7-fold lower dosage, the CF3 significantly (p<0.05) reduced SBP (maximum −40.0 mmHg) better than CPH (maximum −19.1 mmHg).ConclusionsRP-HPLC fractionation led to enhanced antihypertensive effects of cod peptides, which may be due to a stronger renin-inhibitory activity.