Vicinal diaryl pyrazole with tetrazole/urea scaffolds as selective angiotensin converting enzyme-1/cyclooxygenase-2 inhibitors: Design, synthesis, anti-hypertensive, anti-fibrotic, and anti-inflammatory.

As a hybrid weapon, two novel series of pyrazoles, 16a-f and 17a-f, targeting both COX-2 and ACE-1-N-domain, were created and their anti-inflammatory, anti-hypertensive, and anti-fibrotic properties were evaluated. In vitro, 17b and 17f showed COX-2 selectivity (SI = 534.22 and 491.90, respectively) compared to celecoxib (SI = 326.66) and NF-κB (IC50 1.87 and 2.03 µM, respectively). 17b (IC50 0.078 µM) and 17 f (IC50 0.094 µM) inhibited ACE-1 comparable to perindopril (PER) (IC50 0.048 µM). In vivo, 17b decreased systolic blood pressure by 18.6%, 17b and 17f increased serum NO levels by 345.8%, and 183.2%, respectively, increased eNOS expression by 0.97 and 0.52 folds, respectively and reduced NF-κB-p65 and P38-MAPK expression by -0.62, -0.22, -0.53, and -0.24 folds, respectively compared to  l-NAME (-0.34, -0.45 folds decline in NF-κB-p65 and P38-MAPK, respectively). 17b reduced ANG-II expression which significantly reversed the cardiac histological changes induced by L-NAME.

Synthesis of novel calcium channel blockers with ACE2 inhibition and dual antihypertensive/anti-inflammatory effects: A possible therapeutic tool for COVID-19.

Hypertension has been recognized as one of the most frequent comorbidities and risk factors for the seriousness and adverse consequences in COVID-19 patients. 3,4-dihydropyrimidin-2(1H) ones have attracted researchers to be synthesized via Beginilli reaction and evaluate their antihypertensive activities as bioisosteres of nifedipine a well-known calcium channel blocker. In this study, we report synthesis of some bioisosteres of pyrimidines as novel CCBs with potential ACE2 inhibitory effect as antihypertensive agents with protective effect against COVID-19 infection by suppression of ACE2 binding to SARS-CoV-2 Spike RBD. All compounds were evaluated for their antihypertensive and calcium channel blocking activities using nifedipine as a reference standard. Furthermore, they were screened for their ACE2 inhibition potential in addition to their anti-inflammatory effects on LPS-stimulated THP-1 cells. Most of the tested compounds exhibited significant antihypertensive activity, where compounds 7a, 8a and 9a exhibited the highest activity compared to nifedipine. Moreover, compounds 4a,b, 5a,b, 7a,b, 8a,c and 9a showed promising ACE2:SARS-CoV-2 Spike RBD inhibitory effect. Finally, compounds 5a, 7b and 9a exerted a promising anti-inflammatory effect by inhibition of CRP and IL-6 production. Ultimately, compound 9a may be a promising antihypertensive candidate with anti-inflammatory and potential efficacy against COVID-19 via ACE2 receptor inhibition.

Characterization of ACE Inhibitory Peptides Prepared from Pyropia pseudolinearis Protein.

More than 7000 red algae species have been classified. Although most of them are underused, they are a protein-rich marine resource. The hydrolysates of red algal proteins are good candidates for the inhibition of the angiotensin-I-converting enzyme (ACE). The ACE is one of the key factors for cardiovascular disease, and the inhibition of ACE activity is related to the prevention of high blood pressure. To better understand the relationship between the hydrolysates of red algal proteins and the inhibition of ACE activity, we attempted to identify novel ACE inhibitory peptides from Pyropia pseudolinearis. We prepared water soluble proteins (WSP) containing phycoerythrin, phycocyanin, allophycocyanin, and ribulose 1,5-bisphosphate carboxylase/oxygenase. In vitro analysis showed that the thermolysin hydrolysate of the WSP had high ACE inhibitory activity compared to that of WSP. We then identified 42 peptides in the hydrolysate by high-performance liquid chromatography and mass spectrometry. Among 42 peptides, 23 peptides were found in chloroplast proteins. We then synthesized the uncharacterized peptides ARY, YLR, and LRM and measured the ACE inhibitory activity. LRM showed a low IC50 value (0.15 µmol) compared to ARY and YLR (1.3 and 5.8 µmol). In silico analysis revealed that the LRM sequence was conserved in cpcA from Bangiales and Florideophyceae, indicating that the novel ACE inhibitory peptide LRM was highly conserved in red algae.

Novel thiazole-pyrazolone hybrids as potent ACE inhibitors and their cardioprotective effect on isoproterenol-induced myocardial infarction.

A facile synthesis of a group of novel thiazole-pyrazolone hybrids and their investigation for angiotensin-converting enzyme (ACE) inhibition are reported in this study. These compounds were synthesized using a well-known approach, based on the condensation of ethyl acetoacetate with thiazolylhydrazines, and characterized by various spectroscopic and analytical techniques. The entire set of compounds displayed a moderate-to-excellent inhibitory activity against ACE. In particular, compound 4i was found to be the most potent ACE inhibitor and was further studied for cardioprotective effects against isoproterenol (ISO)-induced myocardial infarction (MI) in rats. Compound 4i improved the cardiac function and prevented cardiac injury induced by ISO in Sprague Dawley rats. The levels of oxidative stress and proinflammatory cytokines were also restored to near normal by 4i as compared with the ISO group. In the Western blot analysis, compound 4i prevented mitochondrial apoptosis after MI by downregulating the expression of cleaved caspase-3 and Bax, with the upregulation of Bcl-2, as compared with the ISO group.

Continuous Flow Synthesis of ACE Inhibitors From N-Substituted l-Alanine Derivatives.

A strategy for the continuous flow synthesis of angiotensin converting enzyme (ACE) inhibitors is described. An optimization effort guided by in situ IR analysis resulted in a general amide coupling approach facilitated by N-carboxyanhydride (NCA) activation that was further characterized by reaction kinetics analysis in batch. The three-step continuous process was demonstrated by synthesizing 8 different ACE inhibitors in up to 88 % yield with throughputs in the range of ≈0.5 g h-1 , all while avoiding both isolation of reactive intermediates and process intensive reaction conditions. The process was further developed by preparing enalapril, a World Health Organization (WHO) essential medicine, in an industrially relevant flow platform that scaled throughput to ≈1 g h-1 .

In vitro and in silico studies of novel synthetic ACE-inhibitory peptides derived from Saccharomyces cerevisiae protein hydrolysate.

The structure-function relation of YR-10 (YGKPVAVPAR) was investigated by synthesizing four structural analogs of that including YHR-10 (YGKHVAVHAR), GA-8 (GKPVAVPA), GHA-8 (GKHVAVHA), and PAR-3 (PAR). GA-8 (GKPVAVPA) was synthesized on the basis of simulated enzymatic gastrointestinal digestion performed by bioinformatics tools (expasy-peptide cutter). This study explains the molecular mechanisms for the interaction of synthetic peptides with ACE. The IC50 values of each were 139.554 ±â€¯2.3, 61.91 ±â€¯1.2, 463.230 ±â€¯3.56, 135.135 ±â€¯2.1, 514.024 ±â€¯5.86 µM, respectively. Results indicated that Pro replacement with His in YR-10 and GA-8 increased ACE inhibitory activity respectively, by 55.63% and 70.82%. Removal of Tyr and Arg from respectively N and C terminal positions of YR-10, following in silico simulated gastrointestinal digestion caused the 3.31 fold decrease in ACE inhibitory activity. YHR-10 showed the best docking poses, and GHA-8 exhibited interaction with Zn2+. Lineweaver-Burk plots of most active peptides suggest that they act as noncompetitive inhibitors against ACE.

Potent ACE inhibitors from 5-hydroxy indanone derivatives.

A novel triazole derivatives(±)-2-(hydroxymethyl)-7,8-dihydro-1H-indeno[5,4-b]furan-6(2H)-one (12a-j) were designed and synthesized by the reaction between racemic azide and terminal acetylenes under click chemistry reaction conditions followed by biological evaluation as angiotensin converting enzyme (ACE) inhibitors. ß-Amino alcohol derivatives of 1-indanone (15a-l) were synthesized from 5-hydroxy indanone, it was reacted with epichlorohydrin and followed by oxirane ring opening with various piperazine derivatives. Among the newly synthesized compounds 12b (IC50: 1.388024 µM), 12g (IC50: 1.220696 µM), 12j (IC50: 1.312428 µM) and 15k (IC50: 1.349671 µM) and 15l (IC50: 1.330764 µM) emerged as most active non-carboxylic acid ACE inhibitors with minimal toxicity comparable to clinical drug Lisinopril.

Design, synthesis of novel Triazolones and bis-Triazolones derivatives under ultrasound irradiation and evaluation as potent angiotensin converting enzyme (ACE) inhibitors.

The condensation of several primary amines and diamines with various N1-ethoxycarbonyles N1-tosylhydrazonates (1a-b), triazolones (2) and bis-triazolone (3) resulted in ethanol under ultrasound irradiation. Compared with the conventional methods, the main advantages of the present procedure are milder conditions, shorter reaction time and higher yields. The newly synthesized compounds were evaluated for angiotensin I-converting enzyme (ACE) inhibition. The results were compared to Captopril as a reference drug. Compounds 3b, 2h, 3a, 2d, and 2f showed not only inhibition activity with IC50 values of 0.162, 0.253, 0.253, 0.281 and 0.382 µM, respectively, but also minimal toxicity. The docking of chemical compounds in the ACE active site showed possible inhibitory effect of all compounds on the catalytic activity of the enzyme, which would satisfactorily explain the anti-hypertensive effect of these compounds.

Formulation, Characterization, and Optimization of Captopril Fast-Dissolving Oral Films.

This work aimed to using optimization study to formulate a patient-friendly captopril fast-dissolving oral film with satisfactory disintegration time. Films were made with pullulan and hydroxypropyl methyl cellulose (HPMC) by using the solvent-casting method. Cellulose nanofiber (CNF) was used as a compatibilizer and glycerine was used as a plasticizer. In order to find an optimum formulation, a response surface methodology and a central composite design were employed. The concentration percentages of pullulan and glycerine were considered to be the design factors. Disintegration time, tensile strength, percent elongation at break, and folding endurance were considered to be the responses. The results showed that CNF improved the compatibility and tensile strength of the pullulan and HPMC blend. Also, the rigid nature of CNF reduced the film elongation but the addition of glycerine improved its flexibility. All formulations showed an acceptable uniformity content and dissolution rate. Complete dissolution for all formulations occurred within 2 min. Films with 26% pullulan, 74% HPMC, 1% CNF, and 5% glycerine were reported to be optimum formulations for captopril fast-dissolving oral films, with 95% confidence levels. The in vivo comparison of optimized formulation with a conventional captopril sublingual tablet exhibited significant increase in AUC (~ 62%) and Cmax (~ 52%) and a major decrease in Tmax (~ 33%). The overall results showed that the captopril FDF is a promising candidate for enhanced in vivo orotransmucosal absorption.

Design, Synthesis and Evaluation of Novel 2-Hydroxypyrrolobenzodiazepine-5,11-dione Analogues as Potent Angiotensin Converting Enzyme (ACE) Inhibitors.

Under the guidance of combination of traditional Chinese medicine chemistry (CTCMC), this study describes the preparation of a phenolic acid/dipeptide/borneol hybrid consisting of phenolic acid and a bornyl moiety connected to the dipeptide N-terminal and C-terminal respectively. It also evaluates their angiotensin converting enzyme (ACE) inhibitory and synergistic antihypertensive activities. Briefly, a series of novel 2-hydroxypyrrolobenzodiazepine-5,11-dione analogues were prepared and investigated for their ability to inhibit ACE. The influence of the phenolic acid and bornyl moiety on subsite selectivity is also demonstrated. Among all the new compounds, two compounds-7a and 7g-reveal good inhibition potency in in vitro ACE-inhibitory tests. Interestingly, favorable binding results in molecular docking studies also supported the in vitro results. Additionally, the bioassay showed that oral administration of the two compounds displayed high and long-lasting antihypertensive activity both in acute antihypertensive tests and in therapeutic antihypertensive tests by non-invasive blood pressure measurements in spontaneously hypertensive rats.

New proline-rich oligopeptides from the venom of African adders: Insights into the hypotensive effect of the venoms.

BACKGROUND: The snakes from the Bitis genus are some of the most medically important venomous snakes in sub Saharan Africa, however little is known about the composition and effects of these snake venom peptides. Considering that the victims with Bitis genus snakes have exacerbate hypotension and cardiovascular disorders, we investigated here the presence of angiotensin-converting enzyme modulators on four different species of venoms. METHODS: The peptide fractions from Bitis gabonica gabonica, Bitis nasicornis, Bitis gabonica rhinoceros and Bitis arietans which showed inhibitory activity on angiotensin-converting enzyme were subjected to mass spectrometry analysis. Eight proline-rich peptides were synthetized and their potencies were evaluated in vitro and in vivo. RESULTS: The MS analysis resulted in over 150 sequences, out of which 32 are new proline-rich oligopeptides, and eight were selected for syntheses. For some peptides, inhibition assays showed inhibitory potentials of cleavage of angiotensin I ten times greater when compared to bradykinin. In vivo tests showed that all peptides decreased mean arterial pressure, followed by tachycardia in 6 out of 8 of the tests. CONCLUSION: We describe here some new and already known proline-rich peptides, also known as bradykinin-potentiating peptides. Four synthetic peptides indicated a preferential inhibition of angiotensin-converting enzyme C-domain. In vivo studies show that the proline-rich oligopeptides are hypotensive molecules. GENERAL SIGNIFICANCE: Although proline-rich oligopeptides are known molecules, we present here 32 new sequences that are inhibitors of the angiotensin-converting enzyme and consistent with the symptoms of the victims of Bitis spp, who display severe hypotension.

Paramagnetic bradykinin analogues as substrates for angiotensin I-converting enzyme: Pharmacological and conformation studies.

This study uses EPR, CD, and fluorescence spectroscopy to examine the structure of bradykinin (BK) analogues attaching the paramagnetic amino acid-type Toac (2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid) at positions 0, 3, 7, and 9. The data were correlated with the potencies in muscle contractile experiments and the substrate properties towards the angiotensin I-converting enzyme (ACE). A study of the biological activities in guinea pig ileum and rat uterus indicated that only Toac0-BK partially maintained its native biological potency among the tested peptides. This and its counterpart, Toac3-BK, maintained the ability to act as ACE substrates. These results indicate that peptides bearing Toac probe far from the ACE cleavage sites were more susceptible to hydrolysis by ACE. The results also emphasize the existence of a finer control for BK-receptor interaction than for BK binding at the catalytic site of this metallodipetidase. The kinetic kcat/Km values decreased from 202.7 to 38.9µM-1min-1 for BK and Toac3-BK, respectively. EPR, CD, and fluorescence experiments reveal a direct relationship between the structure and activity of these paramagnetic peptides. In contrast to the turn-folded structures of the Toac-internally labeled peptides, more extended conformations were displayed by N- or C-terminally Toac-labeled analogues. Lastly, this work supports the feasibility of monitoring the progress of the ACE-hydrolytic process of Toac-attached peptides by examining time-dependent EPR spectral variations.

Design, synthesis and evaluation of novel 2-butyl-4-chloroimidazole derived peptidomimetics as Angiotensin Converting Enzyme (ACE) inhibitors.

A series of novel 2-butyl-4-chloro-1-methylimidazole derived peptidomimetics were designed, synthesized and evaluated for their Angiotensin Converting Enzyme (ACE) inhibitor activity. 2-Butyl-4-chloro-1-methylimidazole-5-carboxylic acid 2 obtained after oxidation of respective carboxaldehyde 1, was condensed with various amino acid methyl esters 3a-k to give imidazole-amino acid conjugates 4a-k in very good yields. Ester hydrolysis of 4a-k with aqueous LiOH gave the desired peptidomimetics 5a-k. Screening all the new compounds 4a-k and 5a-k using ACE inhibition assay, resulted five compounds 4i, 4k, 5e, 5h and 5i as potent ACE inhibitors with IC50 of 0.647, 0.531, 1.12, 0.657 and 0.100µM with minimal toxicity. Among them, 5i emerged as most active ACE inhibitor with greater potency than marketed drugs Lisinopril, Ramipril and relatively equipotent to Benazepril, Quinapril and Enalapril.

Synthesis and evaluation of novel triazoles and mannich bases functionalized 1,4-dihydropyridine as angiotensin converting enzyme (ACE) inhibitors.

A series of novel diethyl 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate embedded triazole and mannich bases were synthesized, and evaluated for their angiotensin converting enzyme (ACE) inhibitory activity. Screening of above synthesized compounds for ACE inhibition showed that triazoles functionalized compounds have better ACE inhibitory activity compared to that of mannich bases analogues. Among all triazoles we found 6 h, 6 i and 6 j to have good ACE inhibition activity with IC50 values 0.713 µM, 0.409 µM and 0.653 µM, respectively. Among mannich bases series compounds, only 7c resulted as most active ACE inhibitor with IC50 value of 0.928 µM.

Production of goat milk protein hydrolysate enriched in ACE-inhibitory peptides by ultrafiltration.

A global process for the production of goat milk hydrolysates enriched in angiotensin converting enzyme (ACE) inhibitory peptides was proposed. Firstly, the protein fractions (caseins and whey proteins) were separated by ultrafiltration through a 0·14 µm ceramic membrane. The casein fraction obtained in the retentate stream of the above filtration step was subsequently hydrolysed with a combination of subtilisin and trypsin. After 3 h of reaction, the hydrolysate produced presented an IC50 of 218·50 µg/ml, which represent a relatively high ACE inhibitory activity. Finally, this hydrolysate was filtered through a 50 kDa ceramic membrane until reaching a volume reduction factor of 3. The permeate produced presented an improvement of more than 30% in the ACE inhibitory activity. In contrast, the retentate was concentrated in larger and inactive peptides which led to a decrease of more than 80% in its inhibitory activity. The process suggested in this work was suitable to obtain a potent ACE inhibitory activity product able to be incorporated into food formulas intended to control or lower blood pressure. Moreover, the liquid product could be easily stabilised by spray dried if it would be necessary.

Design, synthesis and evaluation of novel 2-hydroxypyrrolobenzodiazepine-5,11-dione analogues as potent angiotensin converting enzyme (ACE) inhibitors.

A series of novel 10-substituted 2-hydroxypyrrolobenzodiazepine-5,11-diones designed through structure based rational hybridization approach, synthesized by the cyclodehydration of isotonic anhydride with (2S,4R)-4-hydroxypyrrolidine-2-carboxylic acid followed by N-substitution, were evaluated as angiotensin converting enzyme (ACE) inhibitors. Among all the new compounds screened (2R,11aS)-10-((4-bromothiophen-2-yl)methyl)-2-hydroxy-2,3-dihydro-1H-benzo[e]pyrrolo[1,2-a][1,4]diazepine-5,11(10H,11aH)dione, 5v (IC50: 0.272 µM) emerged as most active non-carboxylic acid ACE inhibitor with minimal toxicity comparable to clinical drugs Lisinopril, Benazepril and Ramipril. Favorable binding characteristics in docking studies also supported the experimental results.

Perindopril and ramipril phosphonate analogues as a new class of angiotensin converting enzyme inhibitors.

A series of phosphonate analogues related to perindopril and ramipril were prepared and tested to estimate their ability to inhibit angiotensin converting enzyme. These new synthesized compounds were active ACE inhibitors with a promising activity.

Curcumin and its carbocyclic analogs: structure-activity in relation to antioxidant and selected biological properties.

Curcumin is the major phenolic compound present in turmeric (Curcuma longa L.). Curcumin and 15 novel analogs were investigated for their antioxidant and selected biological activities. Strong relationships between the structure and evaluated activity revealed that the compounds with specific functional groups and carbon skeleton had specific biological profiles. Among the compounds tested, the derivatives (E)-2-(3,4-dimethoxybenzylidene)-5-((E)-3-(3,4-dimethoxyphenyl)acryloyl)cyclopentanone (3e), and (E)-2-(4-hydroxy-3-methoxybenzylidene)-5-((E)-3-(4-hydroxy-3-methoxyphenyl)acryloyl)-cyclopentanone (3d) and the parent compound curcumin exhibited the strongest free radical scavenging and antioxidant capacity. Concerning the other biological activities studied the compound (E)-2-(4-hydroxy-3-methoxybenzylidene)-5-((E)-3-(4-hydroxy-3-methoxy-phenyl)-acryloyl)cyclopentanone (3d) was the most potent angiotensin converting enzyme (ACE) inhibitor, while the derivatives (E)-2-(4-hydroxybenzylidene)-6-((E)-3-(4-hydroxyphenyl)acryloyl)cyclohexanone (2b), (E)-2-(3,4-dimethoxybenzylidene)-6-((E)-3-(3,4-dimethoxyphenyl)acryloyl)cyclohexanone (2e) and (E)-2-(3,4-dimethoxybenzylidene)-5-((E)-3-(3,4-dimethoxyphenyl)acryloyl)cyclopentanone (3e) exhibited strong tyrosinase inhibition. Moreover, (E)-2-(3,4-dimethoxybenzylidene)-6-((E)-3-(3,4-dimethoxyphenyl)-acryloyl)cyclohexanone (2e) was also found to be the strongest human HIV-1 protease inhibitor in vitro among the tested compounds. Cytotoxicity studies using normal human lung cells revealed that the novel curcumin as well as its carbocyclic analogs are not toxic.

New ketomethylene inhibitor analogues: synthesis and assessment of structural determinants for N-domain selective inhibition of angiotensin-converting enzyme.

Angiotensin-converting enzyme (ACE) is a zinc metallopeptidase containing two homologous domains. While the C-domain plays a major role in blood pressure regulation, the N-domain hydrolyzes the antifibrotic agent N-acetyl-Ser-Asp-Lys-Pro. Thus, N-domain selective (N-selective) inhibitors could be useful in the treatment of conditions relating to excessive tissue fibrosis. New keto-ACE analogues were designed that contained functionalities considered important for N-selective inhibitor RXP407 binding, namely, a P(2) Asp, N-acetyl group, and C-terminal amide. Such functionalities were incorporated to assess the structural determinants for N-selective binding in a novel inhibitor template. Inhibitors containing a C-terminal amide and modified P(2)' group were poor inhibitors of the N-domain, with several of these displaying improved inhibition of the C-domain. Molecules with both a C-terminal amide and P(2) Asp were also poor inhibitors and not N-selective. Compounds containing a free C-terminus, a P(2) Asp and protecting group displayed a change of more than 1000-fold N-selectivity compared with the parent molecule. Molecular docking models revealed interaction of these P(2) groups with S(2) residues Tyr369 and Arg381. This study emphasizes the importance of P(2) functionalities in allowing for improved N-selective binding and provides further rationale for the design of N-selective inhibitors, which could be useful in treating tissue fibrosis.

Regioselective Rh(I)-catalyzed sequential hydrosilylation toward the assembly of silicon-based peptidomimetic analogues.

A highly regioselective Rh(I)-catalyzed hydrosilylation of enamides is presented. This mild protocol allows access to a wide variety of different arylsilanes with substitution at the ß-position of the enamide and functionalization on the alkyl chain tethered to the silane. This protocol is extended to include a sequential one-pot hydrosilylation. Using diphenylsilane as the appendage point, hydrosilylation of a protected allyl alcohol followed by hydrosilylation of an enamide generates a complex organosilane in one step. This highly convergent strategy to synthesize these functionalized systems now provides a way for the rapid assembly of a diverse collection of silane-based peptidomimetic analogues.