Identification of a new class of activators of the Hippo pathway with antitumor activity in vitro and in vivo.

The Hippo pathway is a key regulator of tissue growth, organ size, and tumorigenesis. Activating the Hippo pathway by gene editing or pharmaceutical intervention has been proven to be a new therapeutic strategy for treatment of the Hippo pathway-dependent cancers. To now, a number of compounds that directly target the downstream effector proteins of Hippo pathway, including YAP and TEADs, have been disclosed, but very few Hippo pathway activators are reported. Here, we discovered a new class of Hippo pathway activator, YL-602, which inhibited CTGF expression in cells irrespective of cell density and the presence of serum. Mechanistically, YL-602 activates the Hippo pathway via MST1/2, which is different from known activators of Hippo pathway. In vitro, YL-602 significantly induced tumor cell apoptosis and inhibited colony formation of tumor cells. In vivo, oral administration of YL-602 substantially suppressed the growth of cancer cells by activation of Hippo pathway. Overall, YL-602 could be a promising lead compound, and deserves further investigation for its mechanism of action and therapeutic applications.

Discovery of α-Ketoamide inhibitors of SARS-CoV-2 main protease derived from quaternized P1 groups.

Although the SARS-CoV-2 pandemic has ended, multiple sporadic cases still exist, posing a request for more antivirals. The main protease (Mpro) of SARS-CoV-2, a key enzyme for viral replication, is an attractive target for drug development. Here, we report the discovery of a new potent α-ketoamide-containing Mpro inhibitor, N-((R)-1-cyclohexyl-2-(((R)-3-methoxy-1-oxo-1-((1-(2-oxo-2-((thiazol-2-ylmethyl)amino)acetyl)cyclobutyl)amino)propan-2-yl)amino)-2-oxoethyl)-4,4-difluorocyclohexane-1-carboxamide (20j). This compound presented promising enzymatic inhibitory activity against SARS-CoV-2 Mpro with an IC50 value of 19.0 nM, and an excellent antiviral activity in cell-based assay with an EC50 value of 138.1 nM. This novel covalent inhibitor may be used as a lead compound for subsequent drug discovery against SARS-CoV-2.

Discovery of benzodiazepine derivatives as a new class of covalent inhibitors of SARS-CoV-2 main protease.

The COVID-19 pandemic has caused people immense suffering all over the world. Although the World Health Organization (WHO) has announced the end of the pandemic, the sporadic virus epidemic is still ongoing and may exist permanently. Effective antivirals against SARS-CoV-2 are important to deal with the long-term threat. The main protease (Mpro) is a crucial target for drug development due to its role in the process of virus's replication and transcription. Herein, we report benzodiazepine derivatives as a new class of Mpro inhibitors. Structure-activity relationship (SAR) studies led to the discovery of the most active compound, methyl 10-(2-chloroacetyl)-1-oxo-11-(4-(trifluoromethyl)phenyl)-2,3,4,5,10,11-hexahydro-1H-dibenzo[b,e][1,4]-diazepine-7-carboxylate (11a), which shows an IC50 value of 0.180 ± 0.004 µM. The X-ray crystal structure shows that 11a covalently binds to Mpro. Collectively, we have obtained a new small molecule inhibitor targeting Mpro, which can serve as a lead compound for subsequent drug discovery against SARS-CoV-2.

Discovery and structure-activity relationship studies of novel α-ketoamide derivatives targeting the SARS-CoV-2 main protease.

The SARS-CoV-2 main protease (Mpro, also named 3CLpro) is a promising antiviral target against COVID-19 due to its functional importance in viral replication and transcription. Herein, we report the discovery of a series of α-ketoamide derivatives as a new class of SARS-CoV-2 Mpro inhibitors. Structure-activity relationship (SAR) of these compounds was analyzed, which led to the identification of a potent Mpro inhibitor (27h) with an IC50 value of 10.9 nM. The crystal structure of Mpro in complex with 27h revealed that α-ketoamide warhead covalently bound to Cys145s of the protease. In an in vitro antiviral assay, 27h showed excellent activity with an EC50 value of 43.6 nM, comparable to the positive control, Nirmatrelvir. This compound displayed high target specificity for Mpro against human proteases and low toxicity. It also possesses favorable pharmacokinetic properties. Overall, compound 27h could be a promising lead compound for drug discovery targeting SARS-CoV-2 Mpro and deserves further in-depth studies.

Discovery of [1,2,3]Triazolo[4,5-c]quinoline Derivatives as a New Class of Ataxia-Telangiectasia Mutated Kinase Inhibitors.

Ataxia-telangiectasia mutated (ATM) is an atypical serine/threonine protein kinase which is implicated in the repair of DNA double-strand breaks. Numerous reports have shown that ATM inhibition is an attractive target for radiotherapy and chemotherapy sensitization. Herein we report a new series of ATM kinase inhibitors containing the 1H-[1,2,3]triazolo[4,5-c]quinoline scaffold, which was obtained by virtual screening, structural optimization, and structure-activity relationship studies. Among the inhibitors, A011 was one of the most potent, with an IC50 value of 1.0 nM against ATM. In colorectal cancer cells (SW620 and HCT116), A011 was able to inhibit activation of ATM signaling induced by irinotecan (CPT-11) and ionizing radiation and then increased the sensitivity of colorectal cancer cells to irinotecan and ionizing radiation through increasing G2/M arrest and inducing apoptosis. In the SW620 human colorectal adenocarcinoma tumor xenograft model, A011 sensitized SW620 to CPT-11 by inhibiting ATM activity. Collectively, this work has identified a promising lead in the discovery of potent inhibitors against ATM.

A new generation Mpro inhibitor with potent activity against SARS-CoV-2 Omicron variants.

Emerging SARS-CoV-2 variants, particularly the Omicron variant and its sublineages, continually threaten the global public health. Small molecule antivirals are an effective treatment strategy to fight against the virus. However, the first-generation antivirals either show limited clinical efficacy and/or have some defects in pharmacokinetic (PK) properties. Moreover, with increased use of these drugs across the globe, they face great pressure of drug resistance. We herein present the discovery and characterization of a new generation antiviral drug candidate (SY110), which is a potent and selective inhibitor of SARS-CoV-2 main protease (Mpro). This compound displayed potent in vitro antiviral activity against not only the predominant SARS-CoV-2 Omicron sublineage BA.5, but also other highly pathogenic human coronaviruses including SARS-CoV-1 and MERS-CoV. In the Omicron-infected K18-hACE2 mouse model, oral treatment with SY110 significantly lowered the viral burdens in lung and alleviated the virus-induced pathology. Importantly, SY110 possesses favorable PK properties with high oral drug exposure and oral bioavailability, and also an outstanding safety profile. Furthermore, SY110 exhibited sensitivity to several drug-resistance Mpro mutations. Collectively, this investigation provides a promising new drug candidate against Omicron and other variants of SARS-CoV-2.

Discovery of 3-phenyl-1,2,4-oxadiazole derivatives as a new class of SARS-CoV-2 main protease inhibitors.

The ongoing COVID-19 pandemic has led to massive infections and deaths and caused tremendous grief among the people. Although vaccines have played an important role in fighting COVID-19, the situation that the protective effect of current vaccines significantly decreases against mutated strains reminds us of the pressing need for developing effective antiviral therapeutics. The main protease (Mpro) is a key enzyme for SARS-CoV-2 viral replication and transcription and an attractive target for drug development. In this research, we report a new series of Mpro inhibitors containing 3-phenyl-1,2,4-oxadiazole. Structure-activity relationship (SAR) studies led to the discovery of the most active compound, 16d, which showed an IC50 value of 5.27 ± 0.26 µM. Collectively, we obtained a new small molecular inhibitor targeting SARS-CoV-2 Mpro, which contains a new scaffold. This compound could be taken as a lead compound for subsequent drug discovery against SARS-CoV-2.

An orally available Mpro inhibitor is effective against wild-type SARS-CoV-2 and variants including Omicron.

Emerging SARS-CoV-2 variants continue to cause waves of new infections globally. Developing effective antivirals against SARS-CoV-2 and its variants is an urgent task. The main protease (Mpro) of SARS-CoV-2 is an attractive drug target because of its central role in viral replication and its conservation among variants. We herein report a series of potent α-ketoamide-containing Mpro inhibitors obtained using the Ugi four-component reaction. The prioritized compound, Y180, showed an IC50 of 8.1 nM against SARS-CoV-2 Mpro and had oral bioavailability of 92.9%, 31.9% and 85.7% in mice, rats and dogs, respectively. Y180 protected against wild-type SARS-CoV-2, B.1.1.7 (Alpha), B.1.617.1 (Kappa) and P.3 (Theta), with EC50 of 11.4, 20.3, 34.4 and 23.7 nM, respectively. Oral treatment with Y180 displayed a remarkable antiviral potency and substantially ameliorated the virus-induced tissue damage in both nasal turbinate and lung of B.1.1.7-infected K18-human ACE2 (K18-hACE2) transgenic mice. Therapeutic treatment with Y180 improved the survival of mice from 0 to 44.4% (P = 0.0086) upon B.1.617.1 infection in the lethal infection model. Importantly, Y180 was also highly effective against the B.1.1.529 (Omicron) variant both in vitro and in vivo. Overall, our study provides a promising lead compound for oral drug development against SARS-CoV-2.

Discovery of 6,7-dihydro-5H-pyrrolo[3,4-d] pyrimidine derivatives as a new class of ATR inhibitors.

Ataxia telangiectasia and Rad3-related (ATR) kinase is a key regulating protein within the DNA damage response (DDR), responsible for sensing replication stress (RS), and has been considered as a potential target for cancer therapy. Herein, we report the discovery of a series of 6,7-dihydro-5H-pyrrolo[3,4-d]-pyrimidine derivatives as a new class of ATR inhibitors. Among them, compound 5g exhibits an IC50 value of 0.007 µM against ATR kinase. In vitro, 5g displays good anti-tumor activity and could significantly reduce the phosphorylation level of ATR and its downstream signaling protein. Overall, this study provides a promising lead compound for subsequent drug discovery targeting ATR kinase.

SARS-CoV-2 Mpro inhibitors with antiviral activity in a transgenic mouse model.

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continually poses serious threats to global public health. The main protease (Mpro) of SARS-CoV-2 plays a central role in viral replication. We designed and synthesized 32 new bicycloproline-containing Mpro inhibitors derived from either boceprevir or telaprevir, both of which are approved antivirals. All compounds inhibited SARS-CoV-2 Mpro activity in vitro, with 50% inhibitory concentration values ranging from 7.6 to 748.5 nM. The cocrystal structure of Mpro in complex with MI-23, one of the most potent compounds, revealed its interaction mode. Two compounds (MI-09 and MI-30) showed excellent antiviral activity in cell-based assays. In a transgenic mouse model of SARS-CoV-2 infection, oral or intraperitoneal treatment with MI-09 or MI-30 significantly reduced lung viral loads and lung lesions. Both also displayed good pharmacokinetic properties and safety in rats.

Discovery of Potent Small-Molecule SIRT6 Activators: Structure-Activity Relationship and Anti-Pancreatic Ductal Adenocarcinoma Activity.

SIRT6 activation is thought to be a promising target for the treatment of many diseases, particularly cancer. Herein, we report the discovery of a series of new small-molecule SIRT6 activators. Structure-activity relationship analyses led to the identification of the most potent compound, 2-(1-benzofuran-2-yl)-N-(diphenylmethyl) quinoline-4-carboxamide (12q), which showed an EC1.5 value of 0.58 ± 0.12 µM and an EC50 value of 5.35 ± 0.69 µM against SIRT6-dependent peptide deacetylation in FLUOR DE LYS assay. It exhibited weak or no activity against other HDAC family members as well as 415 kinases, indicating good selectivity for SIRT6. 12q significantly inhibited the proliferation and migration of pancreatic ductal adenocarcinoma (PDAC) cells in vitro. It also markedly suppressed the tumor growth in a PDAC tumor xenograft model. This compound showed attractive pharmacokinetic properties. Overall, 12q could be a good lead compound for the treatment of PDAC, and it is worthy of further study.

Discovery of 1,8-disubstituted-[1,2,3]triazolo[4,5-c]quinoline derivatives as a new class of Hippo signaling pathway inhibitors.

Inhibitors of the Hippo signaling pathway have been demonstrated to have a potential clinical application in cases such as tissue repair and organ regeneration. However, there is a lack of potent Hippo pathway inhibitors at present. Herein we report the discovery of a series of 1,8-disubstituted-[1,2,3]triazolo[4,5-c]quinoline derivatives as a new class of Hippo pathway inhibitors by utilizing a cell line-based screening model (A549-CTGF). Structure-activity relationship (SAR) of these compounds was also discussed. The most potent compound in the A549-CTGF cell assay, 11g, was then evaluated by real-time PCR and immunofluorescence assays. Overall, this study provides a starting point for later drug discovery targeting the Hippo signaling pathway.

Analysis of TTSuV1b antibody in porcine serum and its correlation with four antibodies against common viral infectious diseases.

BACKGROUND: The purpose of the present study was to evaluate the correlation between Torque teno sus virus 1b (TTSuV1b) infection and other viral infections or vaccine immunization in conventional pigs. METHODS: With overexpressed and purified viral protein TTSuV1b as antigen, an indirect enzyme-linked immunosorbent assay (ELISA) method for detecting TTSuV1b antibody was established, which demonstrated great specificity and reproducibility. Porcine serum samples (n = 212) were tested using ELISA. Meanwhile, the antibodies against Classical Swine Fever Virus (CSFV), Pseudorabies Virus (PRV), Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), and Porcine Circovirus 2 (PCV2) were also examined using the commercial kits. RESULTS: Statistical analysis indicated that the level of anti-TTSuV1b antibody was positively correlated with the level of anti-PCV2 antibody in a lesser extent; the level of antibodies against TTSuV1b or PCV2 were significantly lower in porcine serum with low level of TTSuV1b virus, implicating the potential consistency and synchronization in the mechanism of TTSuV1b and PCV2 infection. Whereas, antibodies against PRRSV or CSFV showed no statistical significance on comparison with anti-TTSuV1b antibody, implicating that in conventional pigs, the antibody level for PRRSV and CSFV were not significantly influenced by TTSuV1b infection. CONCLUSION: In conclusion, examination of anti-TTSuV1b antibody in porcine serum with the presently established ELISA method would serve as a supplementary approach for etiological investigation, and the combined statistical analysis of the antibodies against four other viruses might help to further understand the TTSuV1b infection as well as its pathogenicity.