Recent progress on the discovery of non-peptidic direct renin inhibitors for the clinical management of hypertension

Oxidative carbonylation of N-protected indoles by Rh(III)-zeolites

The oxidative carbonylation of N-protected indoles was investigated to directly synthesize indole-3-carboxylic acids. Using Rh(III)-zeolites as heterogeneous catalysts, the single-site Rh-species reach unprecedented activities (>100 turnovers), while the metal is readily recovered after reaction. X-ray absorption spectroscopy (XAS) provided evidence for site-isolation of Rh(III) species on the zeolite.

Discovery of Novel 2-Carbamoyl Morpholine Derivatives as Highly Potent and Orally Active Direct Renin Inhibitors

The renin-angiotensin-aldosterone system (RAAS) plays a key role in the regulation of blood pressure. Renin, the first and rate-limiting enzyme of the RAAS, is an attractive target for the treatment of hypertension and cardiovascular/renal diseases. Therefore, various direct renin inhibitors (DRIs) have been researched over recent decades; however, most exhibited poor pharmacokinetics and oral bioavailability due to the peptidomimetic or nonpeptidomimetic structures with a molecular weight (MW) of >600, and only aliskiren is approved. This study introduces a novel class of DRIs comprised of a 2-carbamoyl morpholine scaffold. These compounds have a nonpeptidomimetic structure and a MW of <500. The representative compound 26 was highly potent despite not occupying S1'-S2' sites or the opened flap region used by other DRIs and exerted a significant antihypertensive efficacy via oral administration on double transgenic mice carrying both the human angiotensinogen and the human renin genes.

Discovery of SPH3127: A Novel, Highly Potent, and Orally Active Direct Renin Inhibitor

Renin is the rate-limiting enzyme in the renin-angiotensin-aldosterone system (RAAS) which regulates blood pressure and renal function and hence is an attractive target for the treatment of hypertension and cardiovascular/renal diseases. However, the development of direct renin inhibitors (DRIs) with favorable oral bioavailability has been a longstanding challenge for many years. This problem was thought to be because most of the reported DRIs were peptide-like structures or nonpeptide-like structures with a molecular weight (MW) of > 600. Therefore, we tried to find nonpeptidomimetic DRIs with a MW of < 500 and discovered the promising 2-carbamoyl morpholine derivative 4. In our efforts to improve the pharmacokinetic profile of 4 without a significant increase in the MW, we discovered compound 18 (SPH3127), which demonstrated higher bioavailability and a more potent antihypertensive effect in preclinical models than aliskiren and has completed a phase II clinical trial for essential hypertension.

Spectroscopic, electronic structure, molecular docking, and molecular dynamics simulation study of 7-Trifluoromethyl-1H-indole-2-carboxylic acid as an aromatase inhibitor

The present work encompasses a combined experimental and theoretical investigation of the molecular structure, vibrational wavenumbers, electronic structure at the ground and electronic excited states, molecular electrostatic potential surface of 7-(Trifluoromethyl)-1H-indole-2-carboxylic acid (TICA) and possibility of the title molecule as an aromatase inhibitor using molecular docking and molecular dynamic simulations. A stable conformer has been obtained using potential energy scans by varying appropriate dihedral angles. The obtained minimum energy conformer was further optimized at the 6-311++G (d, p) basis set by applying the most accepted B3LYP functional. A good agreement between experimental and calculated normal modes of vibration has been observed. The hydrogen-bonded interaction between two monomeric units of TICA has been investigated using NBO,QTAIM, and NCI (noncovalent interactions) analysis. Molecular docking of TICA with human placental aromatase (PDB ID: 3S79) reveals the formation of polar hydrogen bonds as well as hydrophobic interactions between the ligand and the protein, right in the binding cavity. TICA satisfies all pharmacokinetic filters (Lipinski rule of five, the Veber rule, Ghose rule, Egan rule, as well as the Muegge rule) and has a high bioavailability score of 0.85. Dynamic stability of the ligand within the binding pocket of the target protein has been confirmed by 100 ns molecular dynamics simulation results. The present study provides an excellent starting point for additional in vivo research, and TICA may eventually serve as a significant therapeutic candidate for the treatment of breast cancer.

Peptidomimetics in Silico

Endogenous peptides as part of physiological processes are targets of interest when it comes to finding desirable therapeutics which are able to modulate molecular interactions. The major limits presented by peptides when they are used as drugs have motivated the research of the synthesis of peptidomimetics obtained through chemical modification and the use of in silico approaches. Here recent works on the discovery of peptidomimetics by computational methods are reported. Together with molecular dynamic simulations, the use of pharmacophore research simulations helps to gain insight into and understand the molecular determinants underlying the physiological processes.

Decades-old renin inhibitors are still struggling to find a niche in antihypertensive therapy. A fleeting look at the old and the promising new molecules

Hypertension is a diverse illness interlinked with cerebral, cardiovascular (CVS) and renal abnormalities. Presently, the malady is being treated by focusing on Renin- angiotensin system (RAS), voltage-gated calcium channels, peripheral vasodilators, renal and sympathetic nervous systems. Cardiovascular and renal abnormalities are associated with the overactivation of RAS, which can be constrained by angiotensin- converting enzyme inhibitors (ACEIs), angiotensin II (Ang-II) -AT1 receptor blockers (ARBs) and renin inhibitors. The latter is a new player in the old system. The renin catalyzes the conversion of angiotensinogen to Angiotensin I (Ang-I). This can be overcome by inhibiting renin, a preliminary step, eventually hinders the occurrence of the cascade of events in the RAS. Various peptidomimetics, the first-generation renin inhibitors developed six decades ago have limited drug-like properties as they suffered from poor intestinal absorption, high liver first-pass metabolism and low oral bioavailability. The development of chemically diverse molecules from peptides to nonpeptides expanded the horizon to achieving direct renin inhibition. Aliskiren, a blockbuster drug that emerged as a clinical candidate and got approved by the US FDA in 2007 was developed by molecular modeling studies. Aliskiren indicated superior to average efficacy and with minor adverse effects relative to other RAS inhibitors. However, its therapeutic use is limited by poor oral bioavailability of less than 2% that is similar to first-generation peptidic compounds. In this review, we present the development of direct renin inhibitors (DRIs) from peptidic to nonpeptidics that lead to the birth of aliskiren, its place in the treatment of cardiovascular diseases and its limitations.

Synthetic strategies, SAR studies, and computer modeling of indole 2 and 3-carboxamides as the strong enzyme inhibitors: a review

Abstract

Indole derivatives have been the focus of many researchers in the study of pharmaceutical compounds for many years. Researchers have investigated the effect of carboxamide moiety at positions 2 and 3, giving unique inhibitory properties to these compounds. The presence of carboxamide moiety in indole derivatives causes hydrogen bonds with a variety of enzymes and proteins, which in many cases, inhibits their activity. In this review, synthetic strategies of indole 2 and 3-carboxamide derivatives, the type, and mode of interaction of these derivatives against HLGP, HIV-1, renin enzyme, and structure–activity studies of these compounds were investigated. It is hoped that indole scaffolds will be tested in the future for maximum activity in pharmacological compounds.

Graphic abstract

Design, synthesis and biological evaluation of renin inhibitors guided by simulated annealing of chemical potential simulations

We have applied simulated annealing of chemical potential (SACP) to a diverse set of ∼150 very small molecules to provide insights into new interactions in the binding pocket of human renin, a historically difficult target for which to find low molecular weight (MW) inhibitors with good bioavailability. In one of its many uses in drug discovery, SACP provides an efficient, thermodynamically principled method of ranking chemotype replacements for scaffold hopping and manipulating physicochemical characteristics for drug development. We introduce the use of Constrained Fragment Analysis (CFA) to construct and analyze ligands composed of linking those fragments with predicted high affinity. This technique addresses the issue of effectively linking fragments together and provides a predictive mechanism to rank order prospective inhibitors for synthesis. The application of these techniques to the identification of novel inhibitors of human renin is described. Synthesis of a limited set of designed compounds provided potent, low MW analogs (IC₅₀s<100nM) with good oral bioavailability (F>20-58%).

Discovery of TAK-272: A Novel, Potent, and Orally Active Renin Inhibitor

The aspartic proteinase renin is an attractive target for the treatment of hypertension and cardiovascular/renal disease such as chronic kidney disease and heart failure. We introduced an S1' site binder into the lead compound 1 guided by structure-based drug design (SBDD), and further optimization of physicochemical properties led to the discovery of benzimidazole derivative 10 (1-(4-methoxybutyl)-N-(2-methylpropyl)-N-[(3S,5R)-5-(morpholin-4-yl)carbonylpiperidin-3-yl]-1H-benzimidazole-2-carboxamide hydrochloride, TAK-272) as a highly potent and orally active renin inhibitor. Compound 10 demonstrated good oral bioavailability (BA) and long-lasting efficacy in rats. Compound 10 is currently in clinical trials.

Small molecule and peptide therapies for chronic heart failure: a patent review (2011 - 2014)

INTRODUCTION

Chronic heart failure (CHF) is the long-term inability of the heart to meet circulatory demands under normal conditions. Effects of CHF can include increased blood volume, increased vascular resistance and compromised contractility leading to fluid retention, dyspnea and fatigue. Current standard of care for chronic systolic heart failure is directed towards managing hypoperfusion through the renin-angiotensin-aldosterone and sympathetic nervous systems. Treatment may also involve reversal of maladaptive cardiac remodeling and prevention of life-threatening arrhythmias.

AREAS COVERED

This review highlights small molecule and peptidic agents for the treatment of CHF with patents published between 2011 and 2014. Targets are subdivided into inotropic agents, ventricular remodeling, diuretics and the renin-angiotensin-aldosterone system.

EXPERT OPINION

CHF represents a large, unmet medical need where improved therapies are needed. The renin-angiotensin-aldosterone system pathway continues to be a major source of new therapies for CHF with new inotropic therapies emerging. Promising initial clinical results for a few approaches combined with the expectation of additional clinical results in the near future make this an exciting time in the pursuit of new treatments for CHF.

trans-(3S,4S)-Disubstituted pyrrolidines as inhibitors of the human aspartyl protease renin. Part I: prime site exploration using an amino linker

Recently, we reported on the discovery of (3S,4S)-disubstituted pyrrolidines (e.g., 2) as inhibitors of the human aspartyl protease renin. In our effort to further expand the scope of this novel class of direct renin inhibitors, a new sub-series was designed in which the prime site substituents are linked to the pyrrolidine core by a (3S)-amino functional group. In particular, analogs bearing the corresponding sulfonamide spacer (50, 51 and 54a) demonstrated a pronounced increase in in vitro potency compared to compound 2.

Structure-based design of substituted piperidines as a new class of highly efficacious oral direct Renin inhibitors

A cis-configured 3,5-disubstituted piperidine direct renin inhibitor, (syn,rac)-1, was discovered as a high-throughput screening hit from a target-family tailored library. Optimization of both the prime and the nonprime site residues flanking the central piperidine transition-state surrogate resulted in analogues with improved potency and pharmacokinetic (PK) properties, culminating in the identification of the 4-hydroxy-3,5-substituted piperidine 31. This compound showed high in vitro potency toward human renin with excellent off-target selectivity, 60% oral bioavailability in rat, and dose-dependent blood pressure lowering effects in the double-transgenic rat model.