Inhibition Of Renin Activity Research Articles

Angiotensin-Converting Enzyme and Renin-Inhibitory Activities of Protein Hydrolysates Produced by Alcalase Hydrolysis of Peanut Protein.

Hypertension is a major controllable risk factor associated with cardiovascular disease (CVD) and overall mortality worldwide. Most people with hypertension must take medications that are effective in blood pressure management but cause many side effects. Thus, it is important to explore safer antihypertensive alternatives to regulate blood pressure. In this study, peanut protein concentrate (PPC) was hydrolyzed with 3-5% Alcalase for 3-10 h. The in vitro angiotensin-converting enzyme (ACE) and renin-inhibitory activities of the resulting peanut protein hydrolysate (PPH) samples and their fractions of different molecular weight ranges were determined as two measures of their antihypertensive potentials. The results show that the crude PPH produced at 4% Alcalase for 6 h of hydrolysis had the highest ACE-inhibitory activity with IC50 being 5.45 mg/mL. The PPH samples produced with 3-5% Alcalase hydrolysis for 6-8 h also displayed substantial renin-inhibitory activities, which is a great advantage over the animal protein-derived bioactive peptides or hydrolysate. Remarkably higher ACE- and renin-inhibitory activities were observed in fractions smaller than 5 kDa with IC50 being 0.85 and 1.78 mg/mL. Hence, the PPH and its small molecular fraction produced under proper Alcalase hydrolysis conditions have great potential to serve as a cost-effective anti-hypertensive ingredient for blood pressure management.

Angiotensin-I-converting enzyme and renin inhibitions by antioxidant shrimp shell protein hydrolysate and ultrafiltration peptide fractions

Protein hydrolysates with 20% and 30% degrees of hydrolysis (DH) were produced from alcalase hydrolysis of Pacific white shrimp shells. The study aimed to investigate the antioxidant and antihypertensive activities of these protein hydrolysates, focusing on peptide fractions of various molecular weights (MW) obtained through ultrafiltration. The 30% DH protein hydrolysate (SSPH) showed the highest antioxidant activities and was subjected to ultrafiltration to produce peptides of various molecular weights (MW) (F1:10–50, F2:5–10, F3:3–5, F4:1-3, and F5:<1 kDa). SSPH showed higher hydrophilic and non-essential amino acid content, among which alanine and aspartic acid were at higher levels. The obtained peptide fractions were analyzed for various antioxidant activities and inhibitory activities against angiotensin-converting enzyme and renin. F4 and F2 samples showed the highest DPPH (2.00 mM TE/g sample) and ABTS (60.68 mM TE/g sample) radical scavenging activities, respectively. Superoxide and hydrogen peroxide radical scavenging activity augmented with decreasing MW, aside from for F1, which showed higher activity than F2–F4 (p < 0.05). The highest ACE-inhibitory activity was found for the F2 fraction (44%–55%), and renin inhibitory activity increased with decreasing MW, in which F5 (12%–22%) was the most effective (p < 0.05). F5 showed 6 major peptides, among which KLVRGSKS and LPKKCLSARPG were the dominant sequences. Thus, this study suggests that shrimp shell protein isolate could be an alternative protein source for peptides with various antioxidant and antihypertensive activities, with potential applications in functional foods and nutraceuticals aimed at mitigating oxidative stress and hypertension.

Antioxidant and Renin Inhibitory Activities of Peptides from Food Proteins on Hypertension: A Review.

Hypertension is a condition induced by oxidative stress causing an alteration in the endothelium, which increases the risk of suffering from other degenerative diseases. This review compiles the findings on peptides from food proteins with antioxidant and antihypertensive activities. Antihypertensive peptides are mainly focused on renin inhibition. Peptides containing hydrophobic amino acids have antioxidant and renin inhibitory activities, as reported by studies on the biological activity of peptides from various food sources evaluated separately and simultaneously. Peptides from food sources can present multiple biological activities. Moreover, antioxidant peptides have the potential to be evaluated against renin, offering an alternative for hypertension therapy without causing adverse side effects.

In vitro anti-hypertensive activity of Jasminum grandiflorum subsp. floribundum (Oleaceae) in relation to its metabolite profile as revealed via UPLC-HRMS analysis

Jasminum is an important genus in the olive family (Oleaceae), comprising about 200 species distributed all over the world. In the current study, the methanolic extract of Jasminum grandiflorum subsp. floribundum aerial parts and its respective fractions; dichloromethane and n-butanol fractions were analyzed using ultra-performance liquid chromatography coupled to high resolution mass (UPLC-HRMS) for profiling and characterization of the plant metabolites. More than seventy metabolites were identified belonging to different classes including phenolic acids, flavonoids, secoiridoids, iridoids, lignans, fatty acids, and triterpenes. The samples were also assessed for their angiotensin-I-converting enzyme (ACE) and renin inhibitory activity along with their antioxidant potential using five complementary assays: TAC (total antioxidant capacity), DPPH (1,1-diphenyl-2-picrylhydrazyl), ABTS (2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid), FRAP (ferric reducing antioxidant power) and iron reducing power. The results revealed that the n-butanol fraction showed a potent ACE and renin inhibition as compared to Lisinopril and Aliskiren standard drugs (24.66 ± 2.41 ng/mL vs. 18.37 ± 1.21 ng/mL and 141.14 ± 5.28 ng/mL vs. 447.87 ± 3.2 ng/mL, respectively) and also a strong antioxidant activity. Interestingly, the secoiridoids, dominated metabolites detected in the n-butanol fraction, revealed the potential of them for management of the hypertension diseases. The total extract and fractions were also standardized using HPLC analysis of the major secoiridoid glycoside; oleuropein. Finally, J. grandiflorum standardized extract could be considered as a target for further studies to discover a new therapeutic anti-hypertensive drug.

Inhibitory Activities of Polyphenolic Extracts of Bangladeshi Vegetables against α-Amylase, α-Glucosidase, Pancreatic Lipase, Renin, and Angiotensin-Converting Enzyme.

The aim of the study was to determine the in vitro enzyme inhibition activities of aqueous polyphenolic extracts of nine popular Bangladeshi vegetables, namely ash gourd, bitter gourd, brinjal, Indian spinach, kangkong, okra, ridge gourd, snake gourd, and stem amaranth. Polyphenolic glycosides were the major compounds present in the extracts. Inhibition of α-amylase (up to 100% at 1 mg/mL) was stronger than α-glucosidase inhibition (up to 70.78% at 10 mg/mL). The Indian spinach extract was the strongest inhibitor of pancreatic lipase activity (IC50 = 276.77 µg/mL), which was significantly better than that of orlistat (381.16 µg/mL), a drug. Ash gourd (76.51%), brinjal (72.48%), and snake gourd (66.82%) extracts were the most effective inhibitors of angiotensin-converting enzyme (ACE), an enzyme whose excessive activities have been associated with hypertension. Brinjal also had a significantly higher renin-inhibitory activity than the other vegetable extracts. We conclude that the vegetable extracts may have the ability to reduce enzyme activities that have been associated with hyperglycemia, hyperlipidemia, and hypertension.

Physicochemical characterisation, molecular docking, and drug-likeness evaluation of hypotensive peptides encrypted in flaxseed proteome

In this study, hypotensive peptides derived from mature flaxseed protein sequences were predicted in silico using BIOPEP-UWM with nine proteases, three each from digestive, plant and microbial sources. The physicochemical properties of 2256 ACE-inhibitory peptides and 267 renin-inhibitory peptides (including seven (7) peptides with dual inhibitory activities against both ACE and renin enzymes) were assessed in silico using the ‘Peptides’ package of R. The hypotensive peptides showed relatively low molecular weight (mol. wt.) range (132 = mol. wt. ≤ 442 Da); broad range of isoelectric point (3.61 = pI ≤ 12.50); both high (>2) and low (≤2) Boman indices, and a variety of hydrophobicity indices (hydrophilic, hydrophobic and amphipathic properties). Following this, the seven peptides with dual ACE and renin inhibitory activities were selected for molecular docking with the respective enzyme receptors. The binding energies of the seven hypotensive peptides with ACE and renin respectively ranged from −36.82 to −25.94 kJ/mol, and −33.05 to −27.61 kJ/mol; and compared well with values recorded for inhibitor drugs, captopril (−26.78 kJ/mol) and aliskiren (−34.73 kJ/mol). The seven peptides inhibited ACE through hydrogen bonds, electrostatic and hydrophobic interactions; and renin, mainly through hydrogen bonds and hydrophobic interactions. In silico prediction of adsorption, digestion, metabolism, excretion and toxicity (ADME/Tox) profile based on physicochemical properties and Lipinski's rule-of-five showed that the peptides were non-toxic and had desirable drug-like properties (flexibility, lipophilicity, molecular weight, gastrointestinal absorption, and bioavailability). This study provides insight into the molecular interactions of hypotensive peptides with their physiological targets, and the potential to develop the bioactive peptides from flaxseed proteins.

Antiangiogenic potentials of ahpatinins obtained from a Streptomyces species

While exploring new angiogenesis inhibitors from microbial metabolites, we recently isolated ahpatininsC, E, and G from a soil‑derived Streptomycessp. 15JA150. AhpatininsC, EandG are known to have pepsin and renin inhibitory activities; however, their antiangiogenic activities and underlying molecular mechanisms have not been fully elucidated. In the present study, the antiangiogenic properties of ahpatininsC, EandG were investigated. The results revealed that the natural compounds significantly inhibited the vascular endothelial growth factor (VEGF)‑induced proliferation, invasion, adhesion, and tube formation of human umbilical vein endothelial cells (HUVECs) without exhibiting any cytotoxicity. It was also revealed that ahpatininE effectively suppressed the neovascularization of the chorioallantoic membranes in growing chick embryos. Notably, ahpatininsC, E, and G led to the downregulation of VEGF‑induced activation of VEGF receptor2 (VEGFR2) and its downstream signaling mediators, including AKT, ERK1/2, JNK, p38, and NF‑κB, in HUVECs. Moreover, they reduced the expression of matrix metalloproteinase (MMP)‑2 and MMP‑9 in the HUVECs following stimulation with VEGF. Furthermore, ahpatininsC, E, and G reduced the tumor cell‑induced invasion and tube forming abilities of HUVECs, as well as the expression of VEGF, by suppressing hypoxia‑inducible factor‑1α (HIF‑1α) activity in U87MG glioblastoma cells. Collectively, the present findings indicated that ahpatininsC, E, and G may be used in anticancer therapy by targeting tumor angiogenesis through the inhibition of both VEGFR2 and HIF‑1α pathways.

Antihypertensive and antioxidant activities of enzymatic wheat bran protein hydrolysates.

Bioactive peptides from plant protein sources have been continuously identified as nutrient supplements for low toxicity but multiple physiological activities such as antihypertensive, antioxidant, and anti-inflammatory. In this study, wheat bran protein isolate was digested with alcalase to produce wheat bran protein hydrolysate (WPH) that was then separated into different peptide fractions (<1, 1-3, 3-5, and 5-10kDa) by membrane ultrafiltration. WPH and the peptide fractions were evaluated for in vitro activities such as antioxidant, renin inhibition, and angiotensin-converting enzyme (ACE) inhibition. In addition, the blood pressure-lowering effects of WPH and the<1kDa peptides were determined by oral administration to spontaneously hypertensive rats (SHRs). Results showed that the ACE and renin inhibitions were significantly (p<.05) higher for the<1kDa fraction (84.25%±2.45%, 75.19%±1.75%, respectively) when compared to the WPH and>1kDa fractions. The<1kDa fraction also showed significantly (p<.05) higher oxygen radical antioxidant activity with 2044.73±37.45 (μM TE/g protein) when compared to lower values obtained for the>1kDa membrane fractions and WPH. Oral administration (100mg/kg body weight) of the<1kDa membrane fraction to SHRs resulted in a better decrease (-35mmHg) in the systolic blood pressure when compared to the WPH (-20mmHg) after 6hr. And seven peptides (NL, QL, FL, HAL, AAVL, AKTVF, and TPLTR) were identified and amino acid sequence was determined by tandem mass spectrometry. We conclude that the WPH could be considered as a suitable natural antihypertensive and antioxidant resource. PRACTICAL APPLICATIONS: The results of the present study indicate that WPH and its ultrafiltration fractions possess potential as a source of antihypertensive and strong antioxidant peptides. It has been proved that wheat bran has a good blood pressure lowering and antioxidation and other biological activities, and the<1kDa fraction showing high oxygen radical absorbance capacity level also has better in vitro ACE inhibition and renin-inhibitory activity. The higher antihypertensive efficiency of the<1kDa fraction may be because the peptides can be better absorbed from the gastrointestinal tract or an increased ability to interact with the enzyme (ACE or renin) protein structure to change the active conformation and lead to decreased catalysis. The results of this study indicate that WPH, especially<1kDa peptide, can be used as a component in formulating antihypertensive functional foods and nutraceuticals, thus improving the industrial production efficiency and bioavailability of wheat bran.

Nicousamide attenuates renal dysfunction and glomerular injury in remnant kidneys by inhibiting TGF-β1 internalisation and renin activity

Nicousamide has been shown to exert renal protective effects against diabetic nephropathy and has moved to a phase II clinical trial in China for diabetic nephropathy indication. To expand its clinical indications, 5/6-nephrectomised rats were used to mimic glomerular and vascular sclerosis and tubulointerstitial scarring, with subsequent progression towards end-stage renal disease. Adult Wistar rats underwent 5/6 nephrectomy to induce the development of chronic kidney disease, with a sham operation performed as a control. The nephrectomised animals were treated orally with either saline, nicousamide (7.5,15, or 45 mg/kg), benazepril (4 mg/kg), or losartan (10 mg/kg) daily for 20 weeks. At 8, 16, and 20 weeks of treatment, blood pressure was measured in each animal, and blood and urine samples were collected for biochemical analysis, while kidney remnants were collected for histological examination. Levels of fibronectin and transforming growth factor beta 1 (TGF-β1) were measured in kidneys by immunohistochemistry. Renin activity in the plasma was measured by an enzyme-linked immunosorbent assay. The results showed that nicousamide treatment significantly reduced systemic hypertension, proteinuria, and blood urea nitrogen (P < 0.05), effectively alleviated glomerular sclerosis scores and tubulointerstitial injuries in a dose-dependent manner (P < 0.01), and markedly decreased fibronectin and TGF-β1 levels in kidney tissues of the 5/6-nephrectomised animals. In vitro studies suggested that nicousamide could moderately inhibit the renin activity and strongly block the TGF-β1 internalisation into fibroblast cells. In summary, nicousamide may protect from renal failure through dual targeting, which involves a TGF-β1-dependent mechanism and inhibition of renin activity.

Food protein-derived renin-inhibitory peptides: in vitro and in vivo properties.

Renin catalyzes the rate-determining step in the renin-angiotensin-aldosterone system that regulates mammalian blood pressure by converting angiotensinogen to angiotensin I (Ang I). Excessive plasma levels of Ang I is a causative factor in hypertension development. Therefore, inhibition of renin activity can lower blood pressure and provide relief from clinical symptoms associated with hypertension. Synthetic compounds are currently the most used group of renin inhibitors; however, only aliskiren is approved as a drug for hypertension treatment. But some negative side effects are associated with aliskiren therapy, which have necessitated the search for alternative natural compounds such as food protein-derived renin-inhibitory peptides with blood pressure-reducing effects. This paper is a concise review of the currently known sources and methods of production of renin-inhibitory peptides including their potential in vitro and in vivo extent of renin inhibition. PRACTICAL APPLICATIONS: Hypertension is a major human chronic disease that leads to severe cardiovascular impairment and ultimately death if not managed properly. Current therapeutic approach to hypertension management involves the use of drugs that inhibit excessive activities of renin and angiotensin converting enzyme (ACE), the two main enzymes that control mammalian blood pressure. Since renin catalyzes a single reaction that is the rate-determining step in the renin-angiotensin system, inhibition of this enzyme activity could be a highly effective strategy for controlling blood pressure without severe negative side effects. However, therapeutic control of renin activity remains difficult with only one approved drug. Some food protein-derived peptides have been found to inhibit renin activity inhibition, which could offer a drug-free treatment for hypertension. Therefore, this review provides a summary of recent developments in the advances and efficacy testing of renin-inhibitory peptides.

Discovery of benzimidazole derivatives as orally active renin inhibitors: Optimization of 3,5-disubstituted piperidine to improve pharmacokinetic profile

We previously identified 2-tert-butyl-4-[(3-methoxypropyl)amino]-N-(2-methylpropyl)-N-[(3S,5R)-5-(morpholin-4-ylcarbonyl)piperidin-3-yl]pyrimidine-5-carboxamide 3 as a potent renin inhibitor. Since 3 showed unacceptably low bioavailability (BA) in rats, structural modification, using SBDD and focused on physicochemical properties was conducted to improve its PK profile while maintaining renin inhibitory activity. Conversion of the amino group attached at the 4-position of pyrimidine to methylene group improved PK profile and decreased renin inhibitory activity. New central cores with carbon side chains were explored to improve potency. We had designed a series of 5-membered azoles and fused heterocycles that interacted with the lipophilic S3 pocket. In the course of modification, renin inhibitory activity was enhanced by the formation of an additional hydrogen bonding with the hydroxyl group of Thr77. Consequently, a series of novel benzimidazole derivatives were discovered as potent and orally bioavailable renin inhibitors. Among those, compound 13 exhibited more than five-fold of plasma renin inhibition than aliskiren in cynomolgus monkeys at dose ratio.

In vitro renin-angiotensin system inhibition and in vivo antihypertensive activity of peptide fractions from lima bean (Phaseolus lunatus L.).

The renin-angiotensin system is key in the physiopathology of arterial hypertension because it converts angiotensin I, via angiotensin I-converting enzyme (ACE), into angiotensin II. In vitro analyses were done of the ACE-inhibitory and renin-inhibitory activities of peptide fractions isolated by enzymatic hydrolysis of lima bean (Phaseolus lunatus) protein. Antihypertensive activity was confirmed in vivo using a rat model. Lima bean protein was hydrolyzed with one of two sequential enzymatic systems (pepsin-pancreatin or Alcalase®-Flavourzyme®). Ultrafiltration of the hydrolysates produced fractions of different molecular weights. The >3 kDa fraction of the pepsin-pancreatin hydrolysate had the highest ACE-inhibitory activity (60.15%, IC50: 172.62 µg mL-1 ), while the >3 KDa fraction of the Alcalase®-Flavourzyme® hydrolysate had the highest in vitro renin-inhibitory activity. A weak correlation (r = 0.44) was found between ACE-inhibitory and renin-inhibitory activities. When tested in vivo, the latter fraction lowered systolic blood pressure by 64% and diastolic blood pressure by 51%. Peptide fractions from lima bean Phaseolus lunatus protein hydrolysates exhibit both in vitro and in vivo antihypertensive activity. Bioactive peptides from lima bean have potential applications as ingredients in functional foods. © 2017 Society of Chemical Industry.

Transport of angiotensin converting enzyme and renin dual inhibitory peptides LY, RALP and TF across Caco-2 cell monolayers

In order for peptides to exert physiological effects, intact transportation or absorption of their degradation fragments with bioactive potency is required. In this study, Caco-2 cell model was employed to investigate the stability of ACE- and renin-inhibitory peptides LY, RALP and TF during cellular absorption. Apparent permeability coefficient was 3.49, 0.32, and 0.94×10−6cm/s for LY, RALP and TF, respectively. LY had the highest infiltration yield of 6.59%, compared to RALP (0.51%) and TF (2.44%) at 180min. Peptides collected from the basolateral sides after 180min had ACE-inhibitory levels of 33.03%, 14.22% and 14.33% with different initial concentrations for LY (2mM), RALP (1mM) and TF (3mM), respectively. In contrast, renin-inhibitory activities were lower at 9.52% (LY) and 7.37% (RALP) while TF had no inhibition. Thus, dipeptides could be more easily absorbed for controlling hypertension and the fragments of RALP had potential antihypertensive properties.

High‐pressure microfluidisation pretreatment disaggregate peanut protein isolates to prepare antihypertensive peptide fractions

SummaryHigh‐pressure microfluidisation (HPM) pretreatment was applied to increase in vitro antihypertensive activity of peanut peptide fractions (PPF). The morphology of protein in aqueous dispersion revealed that peanut protein isolate (PPI) disaggregated at relatively low pressure (≤120 MPa) and re‐aggregated at relatively high pressures (150–210 MPa). The treated pressure of 120 MPa could lead to the most disaggregation of PPI. Small peptides contents, trichloroacetic acid‐nitrogen soluble index (TCA‐NSI) and degree of hydrolysis (DH) of peanut protein hydrolysates (PPH) all reached the highest at 120 MPa. Consequently, it possessed the highest angiotensin converting enzyme (ACE) and renin inhibitory activity. The highest surface hydrophobicity occurred at 120 MPa pretreatment samples. Thirty‐nine oligopeptides at 120 MPa pretreatment were identified by ultra‐performance liquid chromatography‐quadrupole time‐of‐flight (UPLC‐Q‐TOF) mass spectrometer combined with Progenesis QI for Proteomics software compared with 29 and 35 at control and 210 MPa, respectively. This meant that disaggregation of PPI at 120 MPa resulted in the release of new hydrophobic peptide.

Identification of novel human renin inhibitors through a combined approach of pharmacophore modelling, molecular DFT analysis and in silico screening

Renin is an aspartyl protease of the renin–angiotensin system (RAS) and the first enzyme of the biochemical pathway for the generation of angiotensin II – a potent vasoconstrictor involved in the maintenance of cardiovascular homeostasis and the regulation of blood pressure. High enzymatic specificity of renin and its involvement in the catalysis of the rate-limiting step of the RAS hormone system qualify it as a good target for inhibition of hypertension and other associated diseases. Ligand-based pharmacophore model (Hypo1) was generated from a training set of 24 compounds with renin inhibitory activity. The best hypothesis consisted of one Hydrogen Bond Acceptor (HBA), three Hydrophobic Aliphatic (HY-Al) and one Ring Aromatic (AR) features. This well-validated pharmacophore hypothesis (correlation coefficient 0.95) was further utilized as a 3D query to screen database compounds, which included structures from two natural product repositories. These screened compounds were further analyzed for drug-likeness and ADMET studies. The compounds which satisfied the qualifying criteria were then subjected to molecular docking and Density Functional Theory (DFT) analysis in order to discern their atomic level interactions at the active site of the 3D structure of rennin. The pharmacophore-based modelling that has been used to generate the novel findings of the present study would be an avant-garde approach towards the development of potent inhibitors of renin.

Surface plasmon resonance applicability study using immobilized recombinant human renin to screen for renin inhibitory activity

Surface plasmon resonance applicability study using immobilized recombinant human renin to screen for renin inhibitory activity

Plasma Renin Response to Treadmill Exercise in Secondary Hypertension Kidney Disease Patients

Inhibition of renin activity has long been considered to be the logical step to interrupt the renin angiotensin aldosterone system which becomes the cornerstone to retard the progression of Chronic Kidney Disease. Currently, little is known about the impact of aerobic exercise on the plasma renin in chronic kidney disease patients. Aim of this study was to investigate the influence of aerobic exercise on plasma renin in the chronic kidney disease patients with secondary hypertension. Forty chronic kidney disease patients aged 40-55 years were randomly assigned to study group and control group. Study group performed moderate intensity aerobic exercise on an electronic treadmill for 30 minutes, 3 times per week, for 8 weeks. Control group received their medication only and no changes in their life style during the same trail period. The mean values for patients in groups A and B after the study were as following: For Plasma renin level (0.82 ± 0.214) and (2.09 ± 0.468) respectively, for systolic blood pressure (152.1 ± 4.86) and (155.8 ± 5.16) mmHg respectively, for diastolic blood pressure (95 ± 3.81) and (102.6 ± 6.93) mmHg respectively and for 6-minute walk test speed (1.83 ± 0.07) and (1.68 ± 0.06) m/s respectively. There were significant differences between two groups in their Plasma renin level and blood pressure (systolic and diastolic) and 6-minute walk test speed after the study. It was concluded that moderate aerobic exercise resulted in improved kidney functions with chronic kidney disease in pre-dialysis patients as reducing plasma renin and improving the blood pressure with non-significant negative weak correlation between Plasma renin level and blood pressure and a significant moderate negative correlation between exercise improvement and plasma renin.

Bioactive peptides in beef: Endogenous generation through postmortem aging

The present research was performed to investigate endogenous release of bioactive peptides in beef during postmortem aging times (1, 10 and 20days). Gradually decreased Warner-Bratzler shear force (WBSF) values of longissimus thoracis (LT) and semitendinosus (ST) muscles were observed and the degradation of structural proteins and collagen led to release of low-molecular weight (<3kDa) peptides. These peptides exhibited 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, ACE- and renin-inhibitory activities. The peptide sequences were identified by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS). In silico analysis (PeptideRanker and BIOPEP) of their bioactivity potentials demonstrated peptides with the predicted bioactivity scores (>0.8) as well as collagen peptides with bioactivity scores (0.6–0.8). The present findings provide insights on development of healthy beef through postmortem aging at 4°C.

Structure-based design of a new series of N-(piperidin-3-yl)pyrimidine-5-carboxamides as renin inhibitors

The action of the aspartyl protease renin is the rate-limiting initial step of the renin-angiotensin-aldosterone system. Therefore, renin is a particularly promising target for blood pressure as well as onset and progression of cardiovascular and renal diseases. New pyrimidine derivatives 5–14 were designed in an attempt to enhance the renin inhibitory activity of compound 3 identified by our previous fragment-based drug design approach. Introduction of a basic amine essential for interaction with the two aspartic acids in the catalytic site and optimization of the S1/S3 binding elements including an induced-fit structural change of Leu114 (‘Leu-in’ to ‘Leu-out’) by a rational structure-based drug design approach led to the discovery of N-(piperidin-3-yl)pyrimidine-5-carboxamide 14, a 65,000-fold more potent renin inhibitor than compound 3. Surprisingly, this remarkable enhancement in the inhibitory activity of compound 14 has been achieved by the overall addition of only seven heavy atoms to compound 3. Compound 14 demonstrated excellent selectivity over other aspartyl proteases and moderate oral bioavailability in rats.

Development and Validation of a Robust QSAR Model For Piperazine and Keto Piperazine Derivatives as Renin Inhibitors

Background: The renin is a key performer in the reninangiotensin system, and it offers a resource for the beneficial action of hypertension and heart malfunction. The keto piperazine based renin inhibitors have shown greater potential and good biavaibility. Objective: To develop a highly efficient QSAR model for 80 piperazines and keto piperazines to predict renin enzyme inhibitory activity. Methods: The renin inhibitory activity (IC 50) was considered as biological activity. Dragon software, version 5.5 was used for calculation of physicochemical parameters. Sequential MLR (multiple linear regression) is carried out to create quantitative structureactivity relationship models, which were again evaluated in support of statistical significance and analytical capacity by inner and exterior validation. Results: