N-[6-(4-butanoyl-5-methyl-1H-pyrazol-1-yl)pyridazin-3-yl]-5-chloro-1-[2-(4-methylpiperazin-1-yl)-2-oxoethyl]-1H-indole-3-carboxamide (SAR216471), a novel intravenous and oral, reversible, and directly acting P2Y12 antagonist

Development of new pyrazoles as class I HDAC inhibitors: Synthesis, molecular modeling, and biological characterization in leukemia cells

Class I histone deacetylases (HDACs) are considered promising targets in current cancer research. To obtain subtype-selective and potent HDAC inhibitors, we used the aminobenzamide scaffold as the zinc-binding group and prepared new derivatives with a pyrazole ring as the linking group. The synthesized compounds were analyzed in vitro using an enzymatic assay against HDAC1, -2, and -3. Compounds 12b, 15b, and 15i were found to be potent HDAC1 inhibitors, also in comparison to the reference compounds entinostat and tacedinaline, with IC50 values of 0.93, 0.22, and 0.68 μM, respectively. The best compounds were measured for their cellular effect and target engagement in acute myeloid leukemia (AML) cells. In addition, we studied the interaction of the compounds with HDAC subtypes using docking and molecular dynamic simulations. In summary, we have developed a new chemotype of HDAC1 inhibitors that can be used for further structure-based optimization.

Rapid sp3-Enriched Scaffold Generation via a Selective Aziridine Amide Ring-Opening Reaction

Sp3-enriched small molecules play a critical role in developing drug candidates. While designing analogues with greater sp3 character, a methodology utilizing a less explored cyclic-aziridine amide ring-opening reaction to generate sp3-enriched scaffolds has been developed and reported. This methodology enables rapid access to substructures with higher fsp3 values, attracting greater attention within the past few decades. The reaction exhibits a wide reaction scope, featuring a highly sterically hindered phenolic ether, thiophenolic ethers, protected aniline formations, and aliphatic/heteroaromatic ring-containing aziridine amides as substrates. Additionally, this reaction provides access to congested tertiary ether formations through regioselective transformation, applicable to an extensive range of drug discovery targets, construction of complex small molecules, and natural product syntheses. The scaffolds developed show improved physicochemical properties.

Synthesis, structure-activity relationships and biological evaluation of benzimidazole derived sulfonylurea analogues as a new class of antagonists of P2Y1 receptor

The P2Y receptors are responsible for the regulation of various physiological processes including neurotransmission and inflammatory responses. These receptors are also considered as novel potential therapeutic targets for prevention and treatment of thrombosis, neurological disorders, pain, cardiac diseases and cancer. Previously, number of P2Y receptor antagonists has been investigated but they are less potent and non-selective with poor solubility profile. Herein, we present the synthesis of new class of benzimidazole derived sulfonylureas (1a-y) as potent antagonists of P2Y receptors, with the specific aim to explore selective antagonists of P2Y1 receptors. The efficacy and selectivity of the synthesized derivatives 1) against four P2Y receptors i.e., t-P2Y1, h-P2Y2, h-P2Y4, and r-P2Y6Rs was carried out by calcium mobilization assay. The results revealed that except 1b, 1d, 1l, 1m, 1o, 1u, 1v, 1w, and 1y, rest of the synthesized derivatives exhibited moderate to excellent inhibitory potential against P2Y1 receptors. Among the potent antagonists, derivative 1h depicted the maximum inhibition of P2Y1 receptor in calcium signalling assay, with an IC₅₀ value of 0.19 ± 0.04 µM. The potential of inhibition was validated by computational investigations where bonding and non-bonding interactions between ligand and targeted receptor further strengthen the study. The best identified derivative 1h revealed the same binding mechanism as that of already reported selective antagonist of P2Y1 receptor i.e (1-(2- (2-tert-butyl-phenoxy) pyridin-3-yl)-3-4-(trifluoromethoxy) phenylurea but the newly synthesized derivative exhibited better solubility profile. Hence, this derivative can be used as lead candidate for the synthesis of more potential antagonist with much better solubility profile and medicinal importance.

The pyridazine heterocycle in molecular recognition and drug discovery

The pyridazine ring is endowed with unique physicochemical properties, characterized by weak basicity, a high dipole moment that subtends π-π stacking interactions and robust, dual hydrogen-bonding capacity that can be of importance in drug-target interactions. These properties contribute to unique applications in molecular recognition while the inherent polarity, low cytochrome P450 inhibitory effects and potential to reduce interaction of a molecule with the cardiac hERG potassium channel add additional value in drug discovery and development. The recent approvals of the gonadotropin-releasing hormone receptor antagonist relugolix (24) and the allosteric tyrosine kinase 2 inhibitor deucravacitinib (25) represent the first examples of FDA-approved drugs that incorporate a pyridazine ring. In this review, the properties of the pyridazine ring are summarized in comparison to the other azines and its potential in drug discovery is illustrated through vignettes that explore applications that take advantage of the inherent physicochemical properties as an approach to solving challenges associated with candidate optimization.

Graphical Abstract

QSAR, structure-based pharmacophore modelling and biological evaluation of novel platelet ADP receptor (P2Y12) antagonist

P2Y12 has a key role in platelet aggregation and thrombus formation via an ADP-induced platelet activation mechanism. Recently, P2Y12 antagonists have become of great interest in the clinical management of antithrombotic therapy. In light of this, we explored the pharmacophoric space of P2Y12 using structure-based pharmacophore modelling. Subsequently, genetic algorithm and multiple linear regression analyses were conducted to select the best combination of physicochemical descriptors and pharmacophoric models to create useful predictive quantitative structure-activity relationship (QSAR) equation (r 2 = 0.9135, r (adj) 2 = 0.9147, r (PRESS) 2 = 0.9129, LOF = 0.3553). One pharmacophoric model emerged in the QSAR equation and was validated by analysing receiver operating characteristic (ROC) curves. The model was then used to screen 200 000 compounds from the National Cancer Institute (NCI) database. The top-ranked hits were in vitro tested, where their IC50's range between 4.20 to 35.00 μM when measured via the electrode aggregometry assay. Whilst, the VASP phosphorylation assay showed 29.70% platelet reactivity index for NSC618159, which is superior to that of ticagrelor.

Novel Antithrombotic Agents in Ischemic Cardiovascular Disease: Progress in the Search for the Optimal Treatment

Ischemic cardiovascular diseases have a high incidence and high mortality worldwide. Therapeutic advances in the last decades have reduced cardiovascular mortality, with antithrombotic therapy being the cornerstone of medical treatment. Yet, currently used antithrombotic agents carry an inherent risk of bleeding associated with adverse cardiovascular outcomes and mortality. Advances in understanding the pathophysiology of thrombus formation have led to the discovery of new targets and the development of new anticoagulants and antiplatelet agents aimed at preventing thrombus stabilization and growth while preserving hemostasis. In the following review, we will comment on the key limitation of the currently used antithrombotic regimes in ischemic heart disease and ischemic stroke and provide an in-depth and state-of-the-art overview of the emerging anticoagulant and antiplatelet agents in the pipeline with the potential to improve clinical outcomes.

Strategies for targeting the P2Y12 receptor in the central nervous system

The purinergic 2Y type 12 receptor (P2Y₁₂R) is a well-known biological target for anti-thrombotic drugs due to its role in platelet aggregation and blood clotting. While the importance of the P2Y₁₂R in the periphery has been known for decades, much less is known about its expression and roles in the central nervous system (CNS), where it is expressed exclusively on microglia - the first responders to brain insults and neurodegeneration. Several seminal studies have shown that P2Y₁₂ is a robust, translatable biomarker for anti-inflammatory and neuroprotective microglial phenotypes in models of degenerative diseases such as multiple sclerosis and Alzheimer's disease. An enduring problem for studying this receptor in vivo, however, is the lack of selective, high-affinity small molecule ligands that can bypass the blood-brain barrier and accumulate in the CNS. In this Digest, we discuss previous attempts by researchers to target the P2Y₁₂R in the CNS and opine on strategies that may be employed to design and assess the suitability of novel P2Y₁₂ ligands for this purpose going forward.

P2Y12 antagonists: Approved drugs, potential naturally isolated and synthesised compounds, and related in-silico studies

P2Y₁₂ is a platelet surface protein which is responsible for the amplification of P2Y₁ response. It plays a crucial role in platelet aggregation and thrombus formation through an ADP-induced platelet activation mechanism. Despite that P2Y₁₂ platelets' receptor is an excellent target for developing antiplatelet agents, only five approved medications are currently in clinical use which are classified into thienopyridines and nucleoside-nucleotide derivatives. In the past years, many attempts for developing new candidates as P2Y₁₂ inhibitors have been made. This review highlights the importance and the role of P2Y₁₂ receptor as part of the coagulation cascade, its reported congenital defects, and the type of assays which are used to verify and measure its activity. Furthermore, an overview is given of the clinically approved medications, the potential naturally isolated inhibitors, and the synthesised candidates which were tested either in-vitro, in-vivo and/or clinically. Finally, we outline the in-silico attempts which were carried out using virtual screening, molecular docking and dynamics simulations in efforts of designing novel P2Y₁₂ antagonists. Various phytochemical classes might be considered as a corner stone for the discovery of novel P2Y₁₂ inhibitors, whereas a wide range of ring systems can be deliberated as leading scaffolds in that area synthetically and theoretically.

Palladium-catalyzed carbonylative synthesis of indole-3-carboxamides from 2-ethynylanilines and nitroarenes

A facile and straightforward approach for the expedite construction of indole-3-carboxamide skeletons via a palladium-catalyzed carbonylative cyclization of 2-ethynylanilines with nitroarenes has been developed.

Synthesis, characterization and biological evaluation of indomethacin derived thioureas as purinergic (P2Y1, P2Y2, P2Y4, and P2Y6) receptor antagonists

G-protein-coupled receptors for extracellular nucleotides are known as P2Y receptors and are made up of eight members that are encoded by distinct genes and can be classified into two classes based on their affinity for specific G-proteins. P2Y receptor modulators have been studied extensively, but only a few small-molecule P2Y receptor antagonists have been discovered so far and approved by drug agencies. Derivatives of indole carboxamide have been identified as P2Y₁₂ and P2X₇ antagonist, as a result, we developed and tested a series of indole derivatives4a-lhaving thiourea moiety as P2Y receptor antagonist by using a fluorescence-based assay to measure the inhibition of intracellular calcium release in 1321N1 astrocytoma cells that had been stably transfected with the P2Y₁, P2Y₂, P2Y₄ and P2Y₆ receptors. Most of the compounds exhibited moderate to excellent inhibition activity against P2Y₁ receptor subtype. The series most potent compound, 4h exhibited an IC₅₀ value of 0.36 ± 0.01 µM selectivity against other subtypes of P2Y receptor. To investigate the ligand-receptor interactions, the molecular docking studies were carried out. Compound 4h is the most potent P2Y₁ receptor antagonist due to interaction with an important amino acid residue Pro105, in addition to Ile108, Phe119, and Leu102.

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

[Current antiplatelet agents, new inhibitors and therapeutic targets]

Cardiovascular diseases are the leading cause of deaths in the world. Platelets play a major role in the occurrence of these diseases and the development of antiplatelet drugs is a priority in the fight against cardiovascular diseases-associated mortality. Aspirin and thienopyridine-based P2Y12 inhibitors are the main drugs currently used. These molecules target the initiation of platelets activation and are responsible for a moderate inhibitory action. Other antiplatelet agents, as glycoprotein (GP) IIb/IIIa antagonists, inhibit platelet aggregation independently of initial activation-associated pathways, but are responsible for increased hemorrhagic events. Regarding each antiplatelet agent's specific characteristics, the prescription of these drugs must take into account the type of cardiovascular event, the age of the patient, the past medical history, and the potential hemorrhagic adverse events. Thus, there is a need for the development of new molecules with a more targeted effect, maintaining optimal efficiency but with a reduction of the hemorrhagic risk, which is the principal limitation of these treatments.

Progress in the development of antiplatelet agents: Focus on the targeted molecular pathway from bench to clinic

Antiplatelet drugs serve as a first-line antithrombotic therapy for the management of acute ischemic events and the prevention of secondary complications in vascular diseases. Numerous antiplatelet therapies have been developed; however, currently available agents are still associated with inadequate efficacy, risk of bleeding, and variability in individual response. Understanding the mechanisms of platelet involvement in thrombosis and the clinical development process of antiplatelet agents is critical for the discovery of novel agents. The functions of platelets in thrombosis are regulated by two major mechanisms: the interaction between surface receptors and their ligands, and the downstream intracellular signaling pathways. Recently, most of the progress made in antiplatelet drug development has been achieved with P2Y receptor antagonists. Additionally, the usage of GP IIb/IIIa receptor antagonists has decreased, because it is associated with a higher risk of bleeding and thrombocytopenia. Agents targeting other platelet surface receptors such as PARs, TP receptor, EP3 receptor, GPIb-IX-V receptor, P-selectin, as well as intracellular signaling factors, such as PI3Kβ, have been evaluated in an attempt to develop the next generation of antiplatelet drugs, reduce or eliminate interpatient variability of drug efficacy and significantly lower the risk of drug-induced bleeding. The aim of this review is to describe the pathways of platelet activation in thrombosis, and summarize the development process of antiplatelet agents, as well as the preclinical and clinical evaluations performed on these agents.

Developments in inhibiting platelet aggregation based on different design strategies

Platelet aggregation is the central event in hemostasis and thrombosis. Up to now, many agents inhibiting platelet aggregation have been approved for the treatment of thrombotic disorders. In this review, we mainly summarized the progress in the research of platelet aggregation inhibitors based on different design strategies. The advantage and challenge of corresponding targets are also discussed in this article. We hope more platelet aggregation inhibitors with efficacy and safety will be discovered in the future.

Recent Advances of Small Molecular Regulators Targeting G Protein- Coupled Receptors Family for Oncology Immunotherapy

The great clinical success of chimeric antigen receptor T cell (CAR-T) and PD-1/PDL-1 inhibitor therapies suggests the drawing of a cancer immunotherapy age. However, a considerable proportion of cancer patients currently receive little benefit from these treatment modalities, indicating that multiple immunosuppressive mechanisms exist in the tumor microenvironment. In this review, we mainly discuss recent advances in small molecular regulators targeting G Protein-Coupled Receptors (GPCRs) that are associated with oncology immunomodulation, including chemokine receptors, purinergic receptors, prostaglandin E receptor EP4 and opioid receptors. Moreover, we outline how they affect tumor immunity and neoplasia by regulating immune cell recruitment and modulating tumor stromal cell biology. We also summarize the data from recent clinical advances in small molecular regulators targeting these GPCRs, in combination with immune checkpoints blockers, such as PD-1/PDL-1 and CTLA4 inhibitors, for cancer treatments.

Antithrombotic P2Y12 receptor antagonists: recent developments in drug discovery

The P2Y₁₂ receptor is one of eight known P2Y receptor subtypes, and belongs to the G-protein-coupled receptor (GPCR) family. The P2Y₁₂ receptor is highly expressed on blood platelets and in the brain. Potent, selective, peripherally acting antagonists for the P2Y₁₂ receptor are used clinically as antithrombotic drugs. Several different scaffolds have been identified as P2Y₁₂ receptor antagonists, including irreversibly acting thienotetrahydropyridines (prodrugs), and reversible competitive antagonists, including adenine nucleotide analogs, piperazinyl-glutamate-quinolines, -pyridines, and -pyrimidines, and anthraquinone derivatives. Here, we provide an overview of the different scaffolds that have been developed as P2Y₁₂ receptor antagonists, some of which have become important therapeutics.

The progress in the research of antiplatelet agents (1995-2017)

Antiplatelet therapy displays a critical role in the treatment and prevention of antithrombotic disorders. Many new antiplatelet agents have been developed following the emergence of various clinical limitations of classical antiplatelet drugs. This review covers mainly the recent advances in the development of P2Y₁₂ antagonists and GPIIb/IIIa antagonists. Meanwhile, it summarizes promising approaches to new platelet surface receptors such as prostanoid EP3 receptor, thromboxane A₂ prostanoid receptor, protease-activated receptors, GPIb-IX-V receptor and P-selectin. In addition, PI3K_β, a critical protein at the inside signaling pathway of platelet activation is also mentioned as an important antiplatelet target. Moreover, the development of respective drug candidates is discussed in detail.

The Necessary Nitrogen Atom: A Versatile High-Impact Design Element for Multiparameter Optimization

There is a continued desire in biomedical research to reduce the number and duration of design cycles required to optimize lead compounds into high-quality chemical probes or safe and efficacious drug candidates. The insightful application of impactful molecular design elements is one approach toward achieving this goal. The replacement of a CH group with a N atom in aromatic and heteroaromatic ring systems can have many important effects on molecular and physicochemical properties and intra- and intermolecular interactions that can translate to improved pharmacological profiles. In this Perspective, the "necessary nitrogen atom" is shown to be a versatile high-impact design element for multiparameter optimization, wherein ≥10-, 100-, or 1000-fold improvement in a variety of key pharmacological parameters can be realized.

One-pot synthesis of thiazino[2,3,4-hi]indole derivatives through a tandem oxidative coupling/heteroannulation process

A novel and expedient one-pot synthesis of thiazino[2,3,4-hi]indole derivatives was developed through a tandem oxidative coupling/heteroannulation process.

Drug-like Antagonists of P2Y Receptors-From Lead Identification to Drug Development

P2Y receptors are expressed in virtually all cells and tissue types and mediate an astonishing array of biological functions, including platelet aggregation, smooth muscle cell proliferation, and immune regulation. The P2Y receptors belong to the G protein-coupled receptor superfamily and are composed of eight members encoded by distinct genes that can be subdivided into two groups on the basis of their coupling to specific G-proteins. Extensive research has been undertaken to find modulators of P2Y receptors, although to date only a limited number of small-molecule P2Y receptor antagonists have been approved by drug/medicines agencies. This Perspective reviews the known P2Y receptor antagonists, highlighting oral drug-like receptor antagonists, and considers future opportunities for the development of small molecules for clinical evaluation.

Intramolecular functional group differentiation as a strategy for the synthesis of bridged bicyclic β-amino acids

Differentiation of identical electrophilic functional groups (carboxylates) by a strategically placed internal nucleophile (an amino group) in cyclic precursors was used as a key general approach to functionalized azabicyclic scaffolds.

Modeling ligand recognition at the P2Y12 receptor in light of X-ray structural information

The G protein-coupled P2Y12 receptor (P2Y12R) is an important antithrombotic target and of great interest for pharmaceutical discovery. Its recently solved, highly divergent crystallographic structures in complex either with nucleotides (full or partial agonist) or with a nonnucleotide antagonist raise the question of which structure is more useful to understand ligand recognition. Therefore, we performed extensive molecular modeling studies based on these structures and mutagenesis, to predict the binding modes of major classes of P2Y12R ligands previously reported. Various nucleotide derivatives docked readily to the agonist-bound P2Y12R, but uncharged nucleotide-like antagonist ticagrelor required a hybrid receptor resembling the agonist-bound P2Y12R except for the top portion of TM6. Supervised molecular dynamics (SuMD) of ticagrelor binding indicated interactions with the extracellular regions of P2Y12R, defining possible meta-binding sites. Ureas, sulfonylureas, sulfonamides, anthraquinones and glutamic acid piperazines docked readily to the antagonist-bound P2Y12R. Docking dinucleotides at both agonist- and antagonist-bound structures suggested interactions with two P2Y12R pockets. Thus, our structure-based approach consistently rationalized the main structure-activity relationships within each ligand class, giving useful information for designing improved ligands.

Metal-free synthesis of 3,5-disubstituted 1H- and 1-aryl-1H-pyrazoles from 1,3-diyne-indole derivatives employing two successive hydroaminations

The uncatalyzed synthesis of 3,5-disubstituted 1H- and 1-aryl-1H-pyrazoles derived from 1,3-diyne indoles was successfully carried out in PEG 400. The scope and limitations of the reaction were studied.