Design, synthesis and anti-necroptosis activity of fused heterocyclic MLKL inhibitors.

Necroptosis is an important form of programmed cell death (PCD), which is mediated by a death receptor and independent of the caspase proteolytic enzyme. Mixed lineage kinase domain-like (MLKL) is the final effector of necroptosis, playing an irreplaceable role in the execution of necroptosis. However, the studies on MLKL inhibitors are in their infancy. Necrosulfonamide (NSA) is an early-discovered covalent MLKL inhibitor, possessing medium anti-necroptosis activity and a structure-activity relationship (SAR) not widely disclosed. In this study, with the covalent motif maintained, we aim to improve the activity by introducing the terminal fused heterocycles and meanwhile revealing the SAR on the part. As a result, compounds 9 and 14 showed the best activity (EC50 = 148.4 and 595.9 nM) against necroptosis among the analogues by covalently binding to MLKL. The SAR was also concluded to guide further structural optimization in this field.

Cyclic Peptide Keap1-Nrf2 Protein-Protein Interaction Inhibitors: Design, Synthesis, and In Vivo Treatment of Acute Lung Injury.

Directly blocking the Keap1-Nrf2 pathway is a promising strategy for the mitigation of acute lung injury (ALI). Peptide Keap1-Nrf2 inhibitors have been reported to have a high Keap1 binding affinity. However, these inhibitors showed weak activity in cells and/or animals. In this study, we designed a series of linear peptides from an Nrf2-based 9-mer Ac-LDEETGEFL-NH2. To improve the cellular activity, we further designed cyclic peptides based on the crystal complex of Keap1 with a linear peptide. Among them, cyclic 9-mer ZC9 targeting Keap1 showed a better affinity (KD2 = 51 nM). Specifically, it exhibited an acceptable water solubility (>38 mg/mL), better cell permeability, cell activity, and metabolic stability (serum t1/2 > 24 h). In the in vitro LPS-induced oxidative damages and ALI model, ZC9 showed significant dose-response reversal activity without apparent toxicity. In conclusion, our results suggested ZC9 as a lead cyclic peptide targeting the Keap1-Nrf2 pathway for ALI clinical treatment.

Identification of a marine-derived sesquiterpenoid, Compound-8, that inhibits tumour necrosis factor-induced cell death by blocking complex II assembly.

BACKGROUND AND PURPOSE: Tumour necrosis factor (TNF) is a pleiotropic inflammatory cytokine that not only directly induces inflammatory gene expression but also triggers apoptotic and necroptotic cell death, which leads to tissue damage and indirectly exacerbates inflammation. Thus, identification of inhibitors for TNF-induced cell death has broad therapeutic relevance for TNF-related inflammatory diseases. In the present study, we isolated and identified a marine fungus-derived sesquiterpenoid, 9α,14-dihydroxy-6ß-p-nitrobenzoylcinnamolide (named as Cpd-8), that inhibits TNF receptor superfamily-induced cell death by preventing the formation of cytosolic death complex II. EXPERIMENTAL APPROACH: Marine sponge-associated fungi were cultured and the secondary metabolites were extracted to yield pure compounds. Cell viability was measured by ATP-Glo cell viability assay. The effects of Cpd-8 on TNF signalling pathway were investigated by western blotting, immunoprecipitation, and immunofluorescence assays. A mouse model of acute liver injury (ALI) was employed to explore the protection effect of Cpd-8, in vivo. KEY RESULTS: Cpd-8 selectively inhibits TNF receptor superfamily-induced apoptosis and necroptosis. Cpd-8 prevents the formation of cytosolic death complex II and subsequent RIPK1-RIPK3 necrosome, while it has no effect on TNF receptor I (TNFR1) internalization and the formation of complex I in TNF signalling pathway. In vivo, Cpd-8 protects mice against TNF-α/D-GalN-induced ALI. CONCLUSION AND IMPLICATIONS: A marine fungus-derived sesquiterpenoid, Cpd-8, inhibits TNF receptor superfamily-induced cell death, both in vitro and in vivo. This study not only provides a useful research tool to investigate the regulatory mechanisms of TNF-induced cell death but also identifies a promising lead compound for future drug development.

Discovery of novel biaryl benzoxazepinones as dual-mode receptor-interacting protein kinase-1 (RIPK1) inhibitors.

Systemic inflammatory response syndrome (SIRS), an exaggerated defense response of the organism to a noxious stressor, involves a massive inflammatory cascade that ultimately leads to reversible or irreversible end-organ dysfunction and even death. Suppressing RIPK1, a key protein in necroptosis pathway, has been proven to be an effective therapeutic strategy for inflammation and SIRS. In this study, a series of novel biaryl benzoxazepinone RIPK1 inhibitors were designed and synthesized by introducing different aryl substituents at the C7 position of benzoxazepinone. As a result, p-cyanophenyl substituted analog 19 exhibited the most potent in vitro anti-necroptotic effect in HT-29 cells (EC50 = 1.7 nM) and superior protection against temperature loss and death in mice in the TZ-induced SIRS model compared to GSK'772. What's more, in vivo analysis of the levels of inflammatory factors in mice also revealed that compound 19 had better anti-inflammatory activity than GSK'772.

Pharmacokinetic, Tissue Distribution, Metabolite, and Toxicity Evaluation of the Matrine Derivative, (6aS, 10S, 11aR, 11bR, 11cS)-10-Methylaminododecahydro-3a, 7a-Diaza-benzo (de) Anthracene-8-thione.

MASM, a structurally modified derivative of matrine, exhibits superior efficacy in reducing inflammation and liver injury in rats when compared to matrine. This study aims to investigate the pharmacokinetic profile and acute toxicity of MASM. Pharmacokinetic results revealed that MASM exhibited rapid absorption, with a Tmax ranging from 0.21 ± 0.04 h to 1.31 ± 0.53 h, and was eliminated slowly, with a t1/2 of approximately 10 h regardless of the route of administration (intravenous, intraperitoneal, or intragastric). The absolute intragastric bioavailability of MASM in rats was determined to be 44.50%, which was significantly higher than that of matrine (18.5%). MASM was detected in all rat tissues including the brain, and through the utilization of stable isotope-labeled compounds and standard references, ten metabolites of MASM, namely sophocarpine, oxysophocarpine, and oxymatrine, were tentatively identified. The LD50 of MASM in mice was determined to be 94.25 mg/kg, surpassing that of matrine (83.21 mg/kg) based on acute toxicity results. Histopathological and biochemical analysis indicated no significant alterations in the primary organs of the low- to medium-dosage groups of MASM. These findings provide valuable insights into the efficacy and toxicity profile of MASM.

Diallyl trisulfide inhibits 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung cancer via modulating gut microbiota and the PPARγ/NF-κB pathway.

Smoking is the primary risk factor for developing lung cancer. Chemoprevention could be a promising strategy to reduce the incidence and mortality rates of lung cancer. Recently, we reported that A/J mice exposed to tobacco smoke carcinogens displayed the reshaping of gut microbiota. Additionally, garlic oil was found to effectively inhibit the carcinogenic effects of tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in lung tumorigenesis. Diallyl trisulfide (DATS), which is the predominant compound in garlic oil, exhibits various biological activities. To further explore the chemopreventive action and potential mechanism of DATS on lung tumorigenesis, we established a lung adenocarcinoma model in A/J mice stimulated by NNK. Subsequently, we employed multi-omics combined molecular biology technologies to clarify the mechanism. The results indicated that DATS significantly decreased the number of lung tumors in NNK induced A/J mice. Interestingly, we discovered that DATS could modulate gut microbiota, particularly increasing the abundance of F. rodentium, which has inhibitory effects on tumor growth. Mechanistically, DATS could activate the PPARγ pathway, leading to the negative regulation of the NF-κB signaling pathway and subsequent suppression of NF-κB-mediated inflammatory factors. Collectively, these findings provide support for DATS as a potential novel chemopreventive agent for tobacco carcinogen-induced lung cancer.

Diallyl Disulfide Blocks Cigarette Carcinogen 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone-Induced Lung Tumorigenesis via Activation of the Nrf2 Antioxidant System and Suppression of NF-κB Inflammatory Response.

Chemoprevention is a potential strategy to reduce lung cancer incidence and death. Recently, we reported that garlic oil significantly inhibits 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis. Diallyl disulfide (DADS) is a bioactive ingredient in garlic. Our goal was to examine the chemopreventive effectiveness and mechanism of DADS on NNK-triggered lung cancer in vivo and in vitro in the current investigation. The results indicated that DADS significantly reduced the number of lung nodules in the NNK-induced A/J mice. Consistent with the in vivo results, DADS markedly inhibited NNK-induced decrease of MRC-5 cells' viability. Mechanistically, DADS could promote Nrf2 dissociated from the Keap1-Nrf2 complex and accelerate Nrf2 nuclear translocation, which in turn upregulates its downstream target genes. Besides, DADS further inhibited the NF-κB signaling cascade, thus reducing the accumulation of inflammatory factors. Collectively, these discoveries supported the potential of DADS as a novel candidate for the chemoprevention of tobacco-carcinogen-induced lung cancer.

Insight from Linker Investigations: Discovery of a Novel Phenylbenzothiazole Necroptosis Inhibitor Targeting Receptor-Interacting Protein Kinase 1 (RIPK1) from a Phenoxybenzothiazole Compound with Dual RIPK1/3 Targeting Activity.

Necroptosis, a regulated cell death form, is a critical contributor in various inflammatory diseases. We previously identified a phenoxybenzothiazole SZM-610 as a RIPK1 and RIPK3 necroptosis inhibitor. We conducted extensive studies to investigate different chemical components' effects on antinecroptosis activity and RIPK1/3 activity. This study focused on replacing the linker in phenoxybenzothiazoles to assess its impact. Remarkably, compound 10, bearing a novel 3,2'-phenylbenzothiazole scaffold, exhibited fourfold more potent nanomolar activity than SZM-610. Unlike SZM-610, this compound inhibited RIPK1 (Kd = 17 nM) and eliminated RIPK3 inhibition at 5000 nM. Various linkages confirmed the 3,2'-phenylbenzothiazole superior potency. Moreover, this compound specifically inhibited necroptosis by inhibiting RIPK1, RIPK3, and MLKL phosphorylation. In a TNF-induced inflammatory model, it dose-dependently (1.25-5 mg/kg) protected mice from hypothermia and death, surpassing SZM-610's effectiveness. These findings highlight 3,2'-phenylbenzothiazole as a promising lead structure for developing drugs targeting necroptosis-related diseases.

Discovery of marine phidianidine-based Nrf2 activators and their potential against oxLDL- and HG-induced injury in HUVECs.

One effective strategy for treating atherosclerosis is to inhibit the injury of vascular endothelial cells (VECs) induced by oxidized low-density lipoprotein (oxLDL) and high glucose (HG). This study synthesized and evaluated a series of novel Nrf2 activators derived from the marine natural product phidianidine for their ability to protect human umbilical VECs against oxLDL- and HG-induced injury. The results of in vitro bioassays demonstrated that compound D-36 was the most promising Nrf2 activator, effectively inhibiting the apoptosis of HUVECs induced by oxLDL and HG. Furthermore, Nrf2 knockdown experiments confirmed that compound D-36 protected against oxLDL- and HG-induced apoptosis in HUVECs by activating the Nrf2 pathway. These findings provide important insights into a new chemotype of marine-derived Nrf2 activators that could potentially be optimized to develop effective anti-atherosclerosis agents.

Ferroptosis-Regulated Cell Death as a Therapeutic Strategy for Neurodegenerative Diseases: Current Status and Future Prospects.

Ferroptosis is increasingly being recognized as a key element in the pathogenesis of diverse diseases. Recent studies have highlighted the intricate links between iron metabolism and neurodegenerative disorders. Emerging evidence suggests that iron homeostasis, oxidative stress, and neuroinflammation all contribute to the regulation of both ferroptosis and neuronal health. However, the precise molecular mechanisms underlying the involvement of ferroptosis in the pathological processes of neurodegeneration and its impact on neuronal dysfunction remain incompletely understood. In our Review, we provide a comprehensive analysis and summary of the potential molecular mechanisms underlying ferroptosis in neurodegenerative diseases, aiming to elucidate the disease progression of neurodegeneration. Additionally, we discuss potential therapeutic agents that modulate ferroptosis with the goal of identifying novel drug molecules for the treatment of neurodegenerative disorders.

Fluoroindole chalcone analogues targeting the colchicine binding site of tubulin for colorectal oncotherapy.

Colorectal cancer (CRC) is a common malignancy of the gastrointestinal tract with high morbidity and mortality. Our previous studies have demonstrated that indole-chalcone-based compounds targeting tubulin displayed potential cytotoxicity to CRC cells. Herein, three new series of derivatives were systematically designed and synthesized to explore their structure-activity relationship (SAR) against CRC based on prior research. Among them, a representative fluorine-containing analog (FC116) exerted superior efficacy on HCT116 (IC50 = 4.52 nM) and CT26 (IC50 = 18.69 nM) cell lines, and HCT116-xenograft mice with tumor growth inhibition rate of 65.96% (3 mg/kg). Of note, FC116 could also suppress the growth of organoid models (IC50 = 1.8-2.5 nM) and showed adenoma number inhibition rate of 76.25% at the dose of 3 mg/kg in APCmin/+ mice. In terms of mechanism, FC116 could induce endoplasmic reticulum (ER) stress to produce excess reactive oxygen species (ROS), leading to mitochondrial damage to promote the apoptosis of CRC cells by targeting microtubules. Our results support that indole-chalcone compounds are promising tubulin inhibitors and highlight the potential of FC116 to combat CRC.

A potent phosphodiester Keap1-Nrf2 protein-protein interaction inhibitor as the efficient treatment of Alzheimer's disease.

The Keap1-Nrf2 pathway has been established as a therapeutic target for Alzheimer's disease (AD). Directly inhibiting the protein-protein interaction (PPI) between Keap1 and Nrf2 has been reported as an effective strategy for treating AD. Our group has validated this in an AD mouse model for the first time using the inhibitor 1,4-diaminonaphthalene NXPZ-2 with high concentrations. In the present study, we reported a new phosphodiester containing diaminonaphthalene compound, POZL, designed to target the PPI interface using a structure-based design strategy to combat oxidative stress in AD pathogenesis. Our crystallographic verification confirms that POZL shows potent Keap1-Nrf2 inhibition. Remarkably, POZL showed its high in vivo anti-AD efficacy at a much lower dosage compared to NXPZ-2 in the transgenic APP/PS1 AD mouse model. POZL treatment in the transgenic mice could effectively ameliorate learning and memory dysfunction by promoting the Nrf2 nuclear translocation. As a result, the oxidative stress and AD biomarker expression such as BACE1 and hyperphosphorylation of Tau were significantly reduced, and the synaptic function was recovered. HE and Nissl staining confirmed that POZL improved brain tissue pathological changes by enhancing neuron quantity and function. Furthermore, it was confirmed that POZL could effectively reverse Aß-caused synaptic damage by activating Nrf2 in primary cultured cortical neurons. Collectively, our findings demonstrated that the phosphodiester diaminonaphthalene Keap1-Nrf2 PPI inhibitor could be regarded as a promising preclinical candidate of AD.

Analysis on benzothiazole necroptosis inhibitors with chiral substitutions in the solvent-accessible region of RIP kinase domain.

Receptor-interacting protein kinase 1 (RIPK1) and RIPK3, two imperative targets of the necroptosis pathway, are associated with various inflammatory-related diseases. Regulating kinase activity with inhibitors has been confirmed as a promising strategy for inflammation treatment. However, most of the reported type I and II kinase inhibitors of RIPK1 and RIPK3, including benzothiazole compounds discovered by our group, have selective limitations due to interaction with ATP-binding pockets. Fortunately, a solvent exposure E0 region of the kinase domain, which extends into the linker region, has been reported to be related to the potency and selectivity of inhibitors. Hence, based on our previous study, a series of benzothiazole necroptosis inhibitors with chiral substitutions in the linker region were developed to investigate RIPK1/3 inhibitory potency. The results showed a 2-to 6-fold increase in anti-necroptotic activity for these chiral compounds. The improved selectivity on RIPK1 or RIPK3 was demonstrated on different derivatives. Predicted binding conformations of enantiomers with RIPK1/3 gave an explanation for their activity differences, guiding further rational design of chiral necroptosis inhibitors.

Compound-42 alleviates acute kidney injury by targeting RIPK3-mediated necroptosis.

BACKGROUND AND PURPOSE: Necroptosis plays an essential role in acute kidney injury and is mediated by receptor-interacting protein kinase 1 (RIPK1), receptor-interacting protein kinase 3 (RIPK3), and mixed lineage kinase domain-like pseudokinase (MLKL). A novel RIPK3 inhibitor, compound 42 (Cpd-42) alleviates the systemic inflammatory response. The current study was designed to investigate whether Cpd-42 exhibits protective effects on acute kidney injury and reveal the underlying mechanisms. EXPERIMENTAL APPROACH: The effects of Cpd-42 were determined in vivo through cisplatin- and ischaemia/reperfusion (I/R)-induced acute kidney injury and in vitro through cisplatin- and hypoxia/re-oxygenation (H/R)-induced cell damage. Transmission electron microscopy and periodic acid-Schiff staining were used to identify renal pathology. Cellular thermal shift assay and RIPK3-knockout mouse renal tubule epithelial cells were used to explore the relationship between Cpd-42 and RIPK3. Molecular docking and site-directed mutagenesis were used to determine the binding site of RIPK3 with Cpd-42. KEY RESULTS: Cpd-42 reduced human proximal tubule epithelial cell line (HK-2) cell damage, necroptosis and inflammatory responses in vitro. Furthermore, in vivo, cisplatin- and I/R-induced acute kidney injury was alleviated by Cpd-42 treatment. Cpd-42 inhibited necroptosis by interacting with two key hydrogen bonds of RIPK3 at Thr94 and Ser146, which further blocked the phosphorylation of RIPK3 and mitigated acute kidney injury. CONCLUSION AND IMPLICATIONS: Acting as a novel RIPK3 inhibitor, Cpd-42 reduced kidney damage, inflammatory response and necroptosis in acute kidney injury by binding to sites Thr94 and Ser146 on RIPK3. Cpd-42 could be a promising treatment for acute kidney injury.

Protective Effect of a Novel RIPK1 Inhibitor, Compound 4-155, in Systemic Inflammatory Response Syndrome and Sepsis.

Excessive inflammatory response is a critical pathogenic factor for the tissue damage and organ failure caused by systemic inflammatory response syndrome (SIRS) and sepsis. In recent years, drugs targeting RIPK1 have proved to be an effective anti-inflammatory strategy. In this study, we identified a novel anti-inflammatory lead compound 4-155 that selectively targets RIPK1. Compound 4-155 significantly inhibited necroptosis of cells, and its activity is about 10 times higher than the widely studied Nec-1 s. The anti-necroptosis effect of 4-155 was mainly dependent on the inhibition of phosphorylation of RIPK1, RIPK3, and MLKL. In addition, we demonstrated that 4-155 specifically binds RIPK1 by drug affinity responsive target stability (DARTS), immunoprecipitation, kinase assay, and immunofluorescence microscopy. More importantly, compound 4-155 could inhibit excessive inflammation in vivo by blocking RIPK1-mediated necroptosis and not influence the activation of MAPK and NF-κB, which is more potential for the subsequent drug development. Compound 4-155 effectively protected mice from TNF-induced SIRS and sepsis. Using different doses, we found that 6 mg/kg oral administration of compound 4-155 could increase the survival rate of SIRS mice from 0 to 90%, and the anti-inflammatory effect of 4-155 in vivo was significantly stronger than Nec-1 s at the same dose. Consistently, 4-155 significantly reduced serum levels of pro-inflammatory cytokines (TNF-α and IL-6) and protected the liver and kidney from excessive inflammatory damages. Taken together, our results suggested that compound 4-155 could inhibit excessive inflammation in vivo by blocking RIPK1-mediated necroptosis, providing a new lead compound for the treatment of SIRS and sepsis.

Fragment-Based Discovery of Azocyclic Alkyl Naphthalenesulfonamides as Keap1-Nrf2 Inhibitors for Acute Lung Injury Treatment.

Blocking the Kelch-like epichlorohydrin-related protein 1 (Keap1)-nuclear factor-erythroid 2 related factor 2 (Nrf2) pathway is a promising strategy to alleviate acute lung injury (ALI). A naphthalensulfonamide NXPZ-2, targeting Keap1-Nrf2 interaction to release Nrf2, was confirmed to exhibit significant anti-inflammatory activities, however, accompanying nonideal solubility and PK profiles. To further improve the properties, twenty-nine novel naphthalenesulfonamide derivatives were designed by a fragment-based strategy. Among them, compound 10u with a (R)-azetidine group displayed the highest PPI inhibitory activity (KD2 = 0.22 µM). The hydrochloric acid form of 10u exhibited a 9-fold improvement on water solubility (S = 484 µg/mL, pH = 7.0) compared to NXPZ-2 (S = 55 µg/mL, pH = 7.0). It could significantly reduce LPS-induced lung oxidative damages and inflammations in vitro and in vivo. Furthermore, a satisfactory pharmacokinetic property was revealed. In conclusion, the novel azetidine-containing naphthalenesulfonamide represents a promising drug candidate for Keap1-targeting ALI treatment.

Structure optimization of an F-indole-chalcone (FC116) on 4-methoxyphenyl group and therapeutic potential against colorectal cancers with low cytotoxicity.

Advanced metastatic colorectal cancers (CRCs) are regarded as a challenge in clinical cancer therapy. Our previous studies have demonstrated that a representative fluoro-substituted indole-chalcone (FC116), was obtained to display highly potent activity against CRC using multiple in vitro and in vivo mouse models by targeting microtubules. However, several problems, such as low dose tolerance and highly toxic to the brain and colon, low solubility unsuitable for intravenous (i.v.) administration, are still existed and limit further development. Herein, we developed two series of FC116 derivatives on the 4-methoxyphenyl group by a structure-based design strategy. Among them, FC11619 with an amino terminus maintained the in vitro cytotoxicity against HCT-116 CRC in a low nanomolar range. This compound could induce G2/M phase arrest via regulating cyclin B1 expression, produce excess reactive oxygen species (ROS), and target tubulin in CRC cells. In vivo, FC11619 significantly suppressed tumor growth, achieving 65.3 and 73.4 % at doses of 5 and 10 mg/kg/d (i.v., 21 d), which were much better than 54.1% of Taxol at 7 mg/kg. In addition, this compound showed better in vivo tolerance compared to that of FC116 (only 3 mg/kg tolerance, intraperitoneal, i.p.), and no major organ-related toxicity, especially no apparent degenerated neurons, intestinal obstruction in clinical Taxol standard therapy. Taken together, the 4-amino-substitutedphenyl indole-chalcones represent lead compounds as chemotherapy of CRC for further drug development in this field.

Profiling of small-molecule necroptosis inhibitors based on the subpockets of kinase-ligand interactions.

Necroptosis is a highly regulated cell death (RCD) form in various inflammatory diseases. Receptor-interacting protein kinase 1 (RIPK1) and RIPK3 are involved in the pathway. Targeting the kinase domains of RIPK1 and/or 3 is a drug design strategy for related diseases. It is generally accepted that essential reoccurring features are observed across the human kinase domains, including RIPK1 and RIPK3. They present common N- and C-terminal domains that are built up mostly by α-helices and ß-sheets, respectively. The current RIPK1/3 kinase inhibitors mainly interact with the kinase catalytic cleft. This article aims to present an in-depth profiling for ligand-kinase interactions in the crucial cleft areas by carefully aligning the kinase-ligand cocrystal complexes or molecular docking models. The similarity and differential structural segments of ligands are systematically evaluated. New insights on the adaption of the conserved and selective kinase domains to the diversity of chemical scaffolds are also provided. In a word, our analysis can provide a better structural requirement for RIPK1 and RIPK3 inhibition and a guide for inhibitor discovery and optimization of their potency and selectivity.

Targeting Receptor-Interacting Protein Kinase 1 by Novel Benzothiazole Derivatives: Treatment of Acute Lung Injury through the Necroptosis Pathway.

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) are serious and devastating pulmonary manifestations of acute systemic inflammation with high morbidity and mortality worldwide. Currently, there are no specific effective treatments for ALI/ARDS. RIPK1, which contributes to necroptosis and inflammation, is confirmed to be a promising strategy for the treatment of ALI. Herein, 23 benzothiazole derivatives were designed to specifically target RIPK1, and SZM-1209 showed high anti-necroptotic activity (EC50 = 22.4 nM) and kinase selectivity on RIPK1 over RIPK3 (Kd,RIPK1 = 85 nM, Kd,RIPK3 > 10,000 nM). In a mTNF-α-induced systemic inflammatory response syndrome (SIRS) model, SZM-1209 could completely reverse mouse deaths with significant anti-inflammatory effects. Furthermore, in a NNK short-term intratracheal exposure-induced ALI model, SZM-1209 significantly alleviated ALI by reducing pulmonary edema and pathological damage. Collectively, activities of SZM-1209 against RIPK1, necroptosis, SIRS, and ALI warranted further investigation of optimized benzothiazoles as promising lead structures against ALI-related diseases.

Receptor-interacting protein kinase 1 (RIPK1) inhibitor: a review of the patent literature (2018-present).

INTRODUCTION: RIPK1 is a critical mediator of inflammation and cell death, which is associated with extensive neurodegenerative and inflammatory diseases. Recently, RIPK1 has aroused the interests of pharmaceutical industry and research institutions. AREAS COVERED: This review focuses on patent literature covering small-molecule inhibitors of RIPK1 since 2018. SciFinder and PubMed databases were used for patent and literature searching. EXPERT OPINION: Studies of RIPK1 inhibitors for the necroptosis pathway have increased dramatically in recent years. To date, dozens of RIPK1 inhibitors have been reported, and several have entered clinical studies. However, the development of RIPK1 inhibitors is still at a preliminary stage. An understanding of the dosage and disease indications of RIPK1 inhibitors, rational structural optimization, and the optimal clinical setting for new structures will require feedback from further clinical trials. Recently, compared with type III inhibitors, the patents on type II inhibitors have dramatically increased. Most of them contain hybrid structures of type II/III inhibitors occupying the ATP-binding pocket and the back hydrophobic pocket of RIPK1. Patents of RIPK1 degraders were also disclosed, but the role of RIPK1 kinase- independent and dependent in promoting cell death and diseases must be considered.