Synthesis of 5-Benzylamino and 5-Alkylamino-Substituted Pyrimido[4,5-c]quinoline Derivatives as CSNK2A Inhibitors with Antiviral Activity

A series of 5-benzylamine-substituted pyrimido[4,5-c]quinoline derivatives of the CSNK2A chemical probe SGC-CK2-2 were synthesized with the goal of improving kinase inhibitor cellular potency and antiviral phenotypic activity while maintaining aqueous solubility. Among the range of analogs, those bearing electron-withdrawing (4c and 4g) or donating (4f) substituents on the benzyl ring as well as introduction of non-aromatic groups such as the cyclohexylmethyl (4t) were shown to maintain CSNK2A activity. The CSNK2A activity was also retained with N-methylation of SGC-CK2-2, but α-methyl substitution of the benzyl substituent led to a 10-fold reduction in potency. CSNK2A inhibition potency was restored with indene-based compound 4af, with activity residing in the S-enantiomer (4ag). Analogs with the highest CSNK2A potency showed good activity for inhibition of Mouse Hepatitis Virus (MHV) replication. Conformational analysis indicated that analogs with the best CSNK2A inhibition (4t, 4ac, and 4af) exhibited smaller differences between their ground state conformation and their predicted binding pose. Analogs with reduced activity (4ad, 4ae, and 4ai) required more substantial conformational changes from their ground state within the CSNK2A protein pocket

Identification and Utilization of a Chemical Probe to Interrogate the Roles of PIKfyve in the Lifecycle of β-Coronaviruses

From a designed library of indolyl pyrimidinamines, we identified a highly potent and cell-active chemical probe (17) that inhibits phosphatidylinositol-3-phosphate 5-kinase (PIKfyve). Comprehensive evaluation of inhibitor selectivity confirmed that this PIKfyve probe demonstrates excellent kinome-wide selectivity. A structurally related indolyl pyrimidinamine (30) was characterized as a negative control that lacks PIKfyve inhibitory activity and exhibits exquisite selectivity when profiled broadly. Chemical probe 17 disrupts multiple phases of the lifecycle of β-coronaviruses: viral replication and viral entry. The diverse antiviral roles of PIKfyve have not been previously probed comprehensively in a single study or using the same compound set. Our scaffold is a distinct chemotype that lacks the canonical morpholine hinge-binder of classical lipid kinase inhibitors and has a non-overlapping kinase off-target profile with known PIKfyve inhibitors. Our chemical probe set can be used by the community to further characterize the role of PIKfyve in virology

Host Kinase CSNK2 is a Target for Inhibition of Pathogenic SARS-like β-Coronaviruses

Inhibition of the protein kinase CSNK2 with any of 30 specific and selective inhibitors representing different chemotypes, blocked replication of pathogenic human, bat, and murine β-coronaviruses. The potency of in-cell CSNK2A target engagement across the set of inhibitors correlated with antiviral activity and genetic knockdown confirmed the essential role of the CSNK2 holoenzyme in β-coronavirus replication. Spike protein endocytosis was blocked by CSNK2A inhibition, indicating that antiviral activity was due in part to a suppression of viral entry. CSNK2A inhibition may be a viable target for the development of anti-SARS-like β-coronavirus drugs

Synthesis of 5-Benzylamino and 5-Alkylamino-Substituted Pyrimido[4,5-c]quinoline Derivatives as CSNK2A Inhibitors with Antiviral Activity

A series of 5-benzylamine-substituted pyrimido[4,5-c]quinoline derivatives of the CSNK2A chemical probe SGC-CK2-2 were synthesized with the goal of improving kinase inhibitor cellular potency and antiviral phenotypic activity while maintaining aqueous solubility. Among the range of analogs, those bearing electron-withdrawing (4c and 4g) or donating (4f) substituents on the benzyl ring as well as introduction of non-aromatic groups such as the cyclohexylmethyl (4t) were shown to maintain CSNK2A activity. The CSNK2A activity was also retained with N-methylation of SGC-CK2-2, but α-methyl substitution of the benzyl substituent led to a 10-fold reduction in potency. CSNK2A inhibition potency was restored with indene-based compound 4af, with activity residing in the S-enantiomer (4ag). Analogs with the highest CSNK2A potency showed good activity for inhibition of Mouse Hepatitis Virus (MHV) replication. Conformational analysis indicated that analogs with the best CSNK2A inhibition (4t, 4ac, and 4af) exhibited smaller differences between their ground state conformation and their predicted binding pose. Analogs with reduced activity (4ad, 4ae, and 4ai) required more substantial conformational changes from their ground state within the CSNK2A protein pocket

Identification and Utilization of a Chemical Probe to Interrogate the Roles of PIKfyve in the Lifecycle of β-Coronaviruses

From a designed library of indolyl pyrimidinamines we identified a highly potent and cell-active chemical probe (analog 17) that inhibits phosphatidylinositol-3-phosphate 5-kinase (PIKfyve). Comprehensive evaluation of inhibitor selectivity confirmed that this PIKfyve probe demonstrates excellent kinome-wide selectivity. A structurally related indolyl pyrimidinamine (analog 30) was characterized as a suitable negative control analog that lacks PIKfyve inhibitory activity and exhibits exquisite selectivity when profiled against the screenable human kinome. Our chemical probe disrupts multiple phases of the life cycle of β-coronaviruses. We observed potent inhibition of viral replication, reduced viral entry, and impacts on a mediator of viral transmission (lysosomes). Our scaffold is a distinct chemotype versus published PIKfyve inhibitors and lacks the canonical morpholine hinge-binder of classical lipid kinase inhibitors. Our chemical probe set can be used by the community to characterize the role of PIKfyve in virology and beyond

Optimization of 3‑Cyano-7-cyclopropylamino-pyrazolo[1,5‑<i>a</i>]pyrimidines toward the Development of an In Vivo Chemical Probe for CSNK2A

3-Cyano-7-cyclopropylamino-pyrazolo[1,5-a]pyrimidines, including the chemical probe SGC-CK2-1, are potent and selective inhibitors of CSNK2A in cells but have limited utility in animal models due to their poor pharmacokinetic properties. While developing analogues with reduced intrinsic clearance and the potential for sustained exposure in mice, we discovered that phase II conjugation by GST enzymes was a major metabolic transformation in hepatocytes. A protocol for codosing with ethacrynic acid, a covalent reversible GST inhibitor, was developed to improve the exposure of analogue 2h in mice. A double codosing protocol, using a combination of ethacrynic acid and irreversible P450 inhibitor 1-aminobenzotriazole, increased the blood level of 2h by 40-fold at a 5 h time point

Identification and Utilization of a Chemical Probe to Interrogate the Roles of PIKfyve in the Lifecycle of β‑Coronaviruses

From a designed library of indolyl pyrimidinamines, we identified a highly potent and cell-active chemical probe (17) that inhibits phosphatidylinositol-3-phosphate 5-kinase (PIKfyve). Comprehensive evaluation of inhibitor selectivity confirmed that this PIKfyve probe demonstrates excellent kinome-wide selectivity. A structurally related indolyl pyrimidinamine (30) was characterized as a negative control that lacks PIKfyve inhibitory activity and exhibits exquisite selectivity when profiled broadly. Chemical probe 17 disrupts multiple phases of the lifecycle of β-coronaviruses: viral replication and viral entry. The diverse antiviral roles of PIKfyve have not been previously probed comprehensively in a single study or using the same compound set. Our scaffold is a distinct chemotype that lacks the canonical morpholine hinge-binder of classical lipid kinase inhibitors and has a non-overlapping kinase off-target profile with known PIKfyve inhibitors. Our chemical probe set can be used by the community to further characterize the role of PIKfyve in virology

Identification and Utilization of a Chemical Probe to Interrogate the Roles of PIKfyve in the Lifecycle of β‑Coronaviruses

From a designed library of indolyl pyrimidinamines, we identified a highly potent and cell-active chemical probe (17) that inhibits phosphatidylinositol-3-phosphate 5-kinase (PIKfyve). Comprehensive evaluation of inhibitor selectivity confirmed that this PIKfyve probe demonstrates excellent kinome-wide selectivity. A structurally related indolyl pyrimidinamine (30) was characterized as a negative control that lacks PIKfyve inhibitory activity and exhibits exquisite selectivity when profiled broadly. Chemical probe 17 disrupts multiple phases of the lifecycle of β-coronaviruses: viral replication and viral entry. The diverse antiviral roles of PIKfyve have not been previously probed comprehensively in a single study or using the same compound set. Our scaffold is a distinct chemotype that lacks the canonical morpholine hinge-binder of classical lipid kinase inhibitors and has a non-overlapping kinase off-target profile with known PIKfyve inhibitors. Our chemical probe set can be used by the community to further characterize the role of PIKfyve in virology