Design, synthesis, and evaluation of potent RIPK1 inhibitors with in vivo anti-inflammatory activity

New Benzothiazole-Thiadiazole-Based Ketones as Potential Antiviral and Anticancer Agents: Synthesis, DFT, and Molecular Docking Studies

Various substituted benzothiazole-thiadiazole-based ketones 4a-i and 6a-c were synthesized and characterized by the IR, NMR, and MS spectral data. The DFT study of the synthesized ketones 4 and 6 displayed matched configurations of their HOMO and LUMO, with the exception of the nitrophenyl derivatives, whose HOMO extended over the entire molecule. Meanwhile, the antiproliferative effectiveness of the produced ketones was evaluated against diverse cell lines and compared with the reference drug Erlotinib. The ketones exhibited variable inhibitory effects, for example, the ketone 6a has the most potent activity versus Panc-1 (IC50 = 9.34 ± 0.18 μM), whereas 4i showed proper effectiveness against HepG2 (IC50 = 10.91 ± 0.23 μM), and ketone 4a exhibited strong activity against MCF-7 cells (IC50 = 5.66 ± 0.16 μM). Moreover, the H5N1 antiviral efficacy was assessed via a plaque reduction assay, using amantadine as a reference drug. Ketones 2a, 4e, and 4g displayed 100% inhibition, while ketone 4e has the lowest toxic concentration (TC50 61 μg/μL). Furthermore, the molecular docking results revealed that ketone 4e had the highest binding score owing to several interactions with amino acids of 1JU6 residues. Finally, SwissADME analysis of the synthesized ketones provides key insights into their pharmacokinetic properties.

An update on lipophilic efficiency as an important metric in drug design

INTRODUCTION

Lipophilic efficiency (LipE) and lipophilic metabolic efficiency (LipMetE) are valuable tools that can be utilized as part of a multiparameter optimization process to advance a hit to a clinical quality compound.

AREAS COVERED

This review covers recent, effective use cases of LipE and LipMetE that have been published in the literature over the past 5 years. These use cases resulted in the delivery of high-quality molecules that were brought forward to in vivo work and/or to clinical studies. The authors discuss best-practices for using LipE and LipMetE analysis, combined with lipophilicity-focused compound design strategies, to increase the speed and effectiveness of the hit to clinical quality compound optimization process.

EXPERT OPINION

It has become well established that increasing LipE and LipMetE within a series of analogs facilitates the improvement of broad selectivity, clearance, solubility, and permeability and, through this optimization, also facilitates the achievement of desired pharmacokinetic properties, efficacy, and tolerability. Within this article, we discuss lipophilic efficiency-focused optimization as a tool to yield high-quality potential clinical candidates. It is suggested that LipE/LipMetE-focused optimization can facilitate and accelerate the drug-discovery process.

RIPK1 inhibitors: A key to unlocking the potential of necroptosis in drug development

Within the field of medical science, there is a great deal of interest in investigating cell death pathways in the hopes of discovering new drugs. Over the past two decades, pharmacological research has focused on necroptosis, a cell death process that has just been discovered. Receptor-interacting protein kinase 1 (RIPK1), an essential regulator in the cell death receptor signalling pathway, has been shown to be involved in the regulation of important events, including necrosis, inflammation, and apoptosis. Therefore, researching necroptosis inhibitors offers novel ways to treat a variety of disorders that are not well-treated by the therapeutic medications now on the market. The research and medicinal potential of RIPK1 inhibitors, a promising class of drugs, are thoroughly examined in this study. The journey from the discovery of Necrostatin-1 (Nec-1) to the recent advancements in RIPK1 inhibitors is marked by significant progress, highlighting the integration of traditional medicinal chemistry approaches with modern technologies like high-throughput screening and DNA-encoded library technology. This review presents a thorough exploration of the development and therapeutic potential of RIPK1 inhibitors, a promising class of compounds. Simultaneously, this review highlights the complex roles of RIPK1 in various pathological conditions and discusses potential inhibitors discovered through diverse pathways, emphasizing their efficacy against multiple disease models, providing significant guidance for the expansion of knowledge about RIPK1 and its inhibitors to develop more selective, potent, and safe therapeutic agents.

Mechanisms of PANoptosis and relevant small-molecule compounds for fighting diseases

Pyroptosis, apoptosis, and necroptosis are mainly programmed cell death (PCD) pathways for host defense and homeostasis. PANoptosis is a newly distinct inflammatory PCD pathway that is uniquely regulated by multifaceted PANoptosome complexes and highlights significant crosstalk and coordination among pyroptosis (P), apoptosis (A), and/or necroptosis(N). Although some studies have focused on the possible role of PANpoptosis in diseases, the pathogenesis of PANoptosis is complex and underestimated. Furthermore, the progress of PANoptosis and related agonists or inhibitors in disorders has not yet been thoroughly discussed. In this perspective, we provide perspectives on PANoptosome and PANoptosis in the context of diverse pathological conditions and human diseases. The treatment targeting on PANoptosis is also summarized. In conclusion, PANoptosis is involved in plenty of disorders including but not limited to microbial infections, cancers, acute lung injury/acute respiratory distress syndrome (ALI/ARDS), ischemia-reperfusion, and organic failure. PANoptosis seems to be a double-edged sword in diverse conditions, as PANoptosis induces a negative impact on treatment and prognosis in disorders like COVID-19 and ALI/ARDS, while PANoptosis provides host protection from HSV1 or Francisella novicida infection, and kills cancer cells and suppresses tumor growth in colorectal cancer, adrenocortical carcinoma, and other cancers. Compounds and endogenous molecules focused on PANoptosis are promising therapeutic strategies, which can act on PANoptosomes-associated members to regulate PANoptosis. More researches on PANoptosis are needed to better understand the pathology of human conditions and develop better treatment.

Synthesis and evaluation of dihydrofuro[2,3-b]pyridine derivatives as potent IRAK4 inhibitors

Interleukin-1 receptor-associated kinase 4 (IRAK4) is a key regulator to control downstream NF-κB and MAPK signals in the innate immune response and has been proposed as a therapeutic target for the treatment of inflammatory and autoimmune diseases. Herein, a series of IRAK4 inhibitors based on a dihydrofuro[2,3-b]pyridine scaffold was developed. Structural modifications of the screening hit 16 (IC₅₀ = 243 nM) led to IRAK4 inhibitors with improved potency but high clearance (Cl) and poor oral bioavailability, as exemplified by compound 21 (IC₅₀ = 6.2 nM, Cl = 43 ml/min/kg, F = 1.6%, LLE = 5.4). Structure modification aimed at improving LLE and reducing clearance identified compound 38. Compound 38 showed significantly improved clearance while maintained excellent biochemical potency against IRAK4 (IC₅₀ = 7.3 nM, Cl = 12 ml/min/kg, F = 21%, LLE = 6.0). Importantly, compound 38 had favorable in vitro safety and ADME profiles. Furthermore, compound 38 reduced the in vitro production of pro-inflammatory cytokines in both mouse iBMDMs and human PBMCs and was orally efficacious in the inhibition of serum TNF-α secretion in LPS-induced mouse model. These findings suggested that compound 38 has development potential as an IRAK4 inhibitor for the treatment of inflammatory and autoimmune disorders.

Design, synthesis, evaluation and optimization of potent IRAK4 inhibitors alleviating production of inflammatory cytokines in LPS-induced SIRS model

Interleukin-1 receptor associated kinase-4 (IRAK4) has emerged as a therapeutic target for inflammatory and autoimmune diseases. Through reversing the amide of CA-4948 and computer aided structure-activity relationship (SAR) studies, a series of IRAK4 inhibitors with oxazolo[4,5-b]pyridine scaffold were identified. Compound 32 showed improved potency (IC₅₀ = 43 nM) compared to CA-4948 (IC₅₀ = 115 nM), but suffered from hERG inhibition (IC₅₀ = 5.7 μM). Further optimization led to compound 42 with reduced inhibition of hERG (IC₅₀ > 30 μM) and 13-fold higher activity (IC₅₀ = 8.9 nM) than CA-4948. Importantly, compound 42 had favorable in vitro ADME and in vivo pharmacokinetic properties. Furthermore, compound 42 significantly reduced LPS-induced production of serum TNF-α and IL-6 cytokines in the mouse model. The overall profiles of compound 42 support it as a lead for the development of IRAK4 inhibitors for the treatment of inflammatory and autoimmune disorders.

Necroptosis in CNS diseases: Focus on astrocytes

In the last few years, necroptosis, a recently described type of cell death, has been reported to play an important role in the development of various brain pathologies. Necroptosis is a cell death mechanism that has morphological characteristics similar to necrosis but is mediated by fundamentally different molecular pathways. Necroptosis is initiated by signaling through the interaction of RIP1/RIP3/MLKL proteins (receptor-interacting protein kinase 1/receptor-interacting protein kinase 3/mixed lineage kinase domain-like protein). RIPK1 kinase is usually inactive under physiological conditions. It is activated by stimulation of death receptors (TNFR1, TNFR2, TLR3, and 4, Fas-ligand) by external signals. Phosphorylation of RIPK1 results in the formation of its complex with death receptors. Further, complexes with the second member of the RIP3 and MLKL cascade appear, and the necroptosome is formed. There is enough evidence that necroptosis plays an important role in the pathogenesis of brain ischemia and neurodegenerative diseases. In recent years, a point of view that both neurons and glial cells can play a key role in the development of the central nervous system (CNS) pathologies finds more and more confirmation. Astrocytes play complex roles during neurodegeneration and ischemic brain damage initiating both impair and protective processes. However, the cellular and molecular mechanisms that induce pathogenic activity of astrocytes remain veiled. In this review, we consider these processes in terms of the initiation of necroptosis. On the other hand, it is important to remember that like other types of programmed cell death, necroptosis plays an important role for the organism, as it induces a strong immune response and is involved in the control of cancerogenesis. In this review, we provide an overview of the complex role of necroptosis as an important pathogenetic component of neuronal and astrocyte death in neurodegenerative diseases, epileptogenesis, and ischemic brain damage.

Advances in RIPK1 kinase inhibitors

Programmed necrosis is a new modulated cell death mode with necrotizing morphological characteristics. Receptor interacting protein 1 (RIPK1) is a critical mediator of the programmed necrosis pathway that is involved in stroke, myocardial infarction, fatal systemic inflammatory response syndrome, Alzheimer's disease, and malignancy. At present, the reported inhibitors are divided into four categories. The first category is the type I ATP-competitive kinase inhibitors that targets the area occupied by the ATP adenylate ring; The second category is type Ⅱ ATP competitive kinase inhibitors targeting the DLG-out conformation of RIPK1; The third category is type Ⅲ kinase inhibitors that compete for binding to allosteric sites near ATP pockets; The last category is others. This paper reviews the structure, biological function, and recent research progress of receptor interaction protein-1 kinase inhibitors.

Discovery of a New Class of Uracil Derivatives as Potential Mixed Lineage Kinase Domain-like Protein (MLKL) Inhibitors

Necroptosis is a form of programmed cell death. Mixed lineage kinase domain-like protein (MLKL) is the necroptosis executor, and it is involved in various diseases such as tissue damage and neurodegeneration-related diseases. Here, we report the development of novel MLKL inhibitors with a uracil nucleus through scaffold morphing from our previously reported xanthine MLKL inhibitor TC13172. After a rational structure-activity relationship study, we obtained the highly potent compounds 56 and 66. Mechanism studies revealed that these compounds partially inhibited MLKL oligomerization and significantly inhibited MLKL translocation to the membrane. Compared with TC13172, 56 and 66 have a different mode of action and, importantly, their reaction rate with glutathione is more than 150-fold lower. This reduction in potential off-target effects and cell toxicity makes this series an attractive starting point for further drug development for MLKL-related disease treatments.