Optimization and Synthesis of Pyridazinone Derivatives as Novel Inhibitors of Hepatitis B Virus by Inducing Genome-free Capsid Formation.

The capsid of hepatitis B virus (HBV) plays a vital role in virus DNA replication. Targeting nucleocapsid function has been demonstrated as an effective approach for anti-HBV drug development. A high-throughput screening and mechanism study revealed the hit compound 4a as an HBV assembly effector (AEf), which could inhibit HBV replication by inducing the formation of HBV DNA-free capsids. The subsequent SAR study and drug-like optimization resulted in the discovery of the lead candidate 4r, with potent antiviral activity (IC50 = 0.087 ± 0.002 µM), low cytotoxicity (CC50 = 90.6 ± 2.06 µM), sensitivity to nucleoside analogue-resistant HBV mutants, and synergistic effect with nucleoside analogues in HepG2.2.15 cells.

Design and synthesis of novel benzo[d]oxazol-2(3H)-one derivatives bearing 7-substituted-4-enthoxyquinoline moieties as c-Met kinase inhibitors.

Analysis of the results of studies of docking 1 and 7a with c-Met kinase led to the identification of benzo[d]oxazol-2(3H)-one-quinolone derivatives as potential inhibitors of this enzyme. A molecular hybrid strategy, using a 4-ethoxy-7-substituted-quinoline core and a benzo[d]oxazol-2(3H)-one scaffold, was employed to design members of this family for study as inhibitors of the kinase and proliferation of EBC-1 cells. Most of the substances were found to display good to excellent c-Met kinase inhibitory activities. The results of a structure-activity relationship (SAR) study led to the discovery of benzo[d]oxazol-2(3H)-one-quinolone 13, which has IC50 values of 1 nM against c-Met kinase and 5 nM against proliferation of the EBC-1 cell line.

A novel pyridazinone derivative inhibits hepatitis B virus replication by inducing genome-free capsid formation.

Here we first identified a novel pyridazinone derivative, compound 3711, as a nonnucleosidic hepatitis B virus (HBV) inhibitor in a cell model system. 3711 decreased extracellular HBV DNA levels by 50% (50% inhibitory concentration [IC50]) at 1.5 ± 0.2 µM and intracellular DNA levels at 1.9 ± 0.1 µM, which demonstrated antiviral activity at levels far below those associated with toxicity. Both the 3TC/ETV dually resistant L180M/M204I mutant and the adefovir (ADV)-resistant A181T/N236T mutant were as susceptible to 3711 as wild-type HBV. 3711 treatment induced the formation of genome-free capsids, a portion of which migrated faster on 1.8% native agarose gel. The induced genome-free capsids sedimented more slowly in isopycnic CsCl gradient centrifugation without significant morphological changes. 3711 treatment decreased levels of HBV DNA contained in both secreted enveloped virion and naked virus particles in supernatant. 3711 could interfere with capsid formation of the core protein (Cp) assembly domain. A Cp V124W mutant, which strengthens capsid interdimer interactions, recapitulated the effect of 3711 on capsid assembly. Pyridazinone derivative 3711, a novel chemical entity and HBV inhibitor, may provide a new opportunity to combat chronic HBV infection.

Enhancing the cellular anti-proliferation activity of pyridazinones as c-met inhibitors using docking analysis.

A series of 2, 6-disubstituted pyridazinone derivatives were evaluated and optimized for their c-Met inhibitory activity in enzyme and cellular assay. An analysis of the SAR results arising from computer modeling analysis of members of the library led to the proposal that in order to obtain optimal inhibitory activity in cellular systems the lipophilic/hydrophilic properties of individual structural fragments in the inhibitors need to match those of corresponding binding pockets in the enzyme. Guided by this proposal, the quinoline-pyridazinone 8a, containing hydrophobic 6-indolyl pyridazinone and quinoline moieties along with a hydrophilic morpholine terminal group, was designed and synthesized. The results of studies with this substance showed that it is a selective c-Met inhibitor with both a high enzyme inhibition IC50 value of 4.2 nM and a high EBC-1 cell proliferation inhibition IC50 value of 17 nM.

Yhhu3813 is a novel selective inhibitor of c-Met kinase that inhibits c-Met-dependent neoplastic phenotypes of human cancer cells.

AIM: c-Met kinase deregulation is strongly associated with the formation, progression and dissemination of human cancers. In this study we identified Yhhu3813 as a small-molecule inhibitor of c-Met kinase and characterized its antitumor properties both in vitro and in vivo. METHODS: The activities of different kinases were measured using ELISA assays and signaling proteins in the cells were detected with Western blotting. Cell proliferation was assessed using SRB or MTT assay in twenty human cell lines and cell cycle distribution was determined with flow cytometry. Transwell-based assay was used to evaluate cell migration and invasion. Cell invasive growth was detected by a morphogenesis assay. c-Met overactivated human NSCLC cell line EBC-1 xenografts were used to evaluate the in vivo anti-tumor efficacy. RESULTS: Yhhu3813 potently inhibited c-Met kinase activity in vitro with an IC50 value of 2.4±0.3 nmol/L, >400-fold higher than that for a panel of 15 different tyrosine kinases, suggesting a high selectivity of Yhhu3813. The compound (20, 100 and 500 nmol/L) dose-dependently inhibited the phosphorylation of c-Met and its key downstream Akt and Erk signal cascades in multiple c-Met aberrant human cancer cell lines, regardless of the mechanistic complexity in c-Met activation across different cellular contexts. In 20 human cancer cell lines harboring different backgrounds of c-Met expression/activation, Yhhu3813 potently inhibited c-Met-driven cell proliferation via arresting cells at G1/S phase. Furthermore, Yhhu3813 substantially impaired c-Met-mediated cell migration, invasion, scattering, and invasive growth. Oral administration of EBC-1 xenograft mice with Yhhu3813 (50 or 100 mg·kg(-1)·d(-1), qd, for 2 weeks) dose-dependently suppressed the tumor growth, which was correlated with a reduction in the intratumoral proliferation index and c-Met signaling. CONCLUSION: Yhhu3813 is a potent selective inhibitor of c-Met that inhibits c-Met-dependent neoplastic phenotypes of human cancer cells in vitro and in vivo.

Discovery of novel 2,6-disubstituted pyridazinone derivatives as acetylcholinesterase inhibitors.

2,6-Disubstituted pyridazinone 4 was identified by HTS as a novel acetylcholinesterase (AChE) inhibitor. Under SAR development, compound 17e stood out as displaying high AChE inhibitory activity and AChE/butyrylcholinesterase (BuChE) selectivity in vitro. Docking studies revealed that 17e might interact with the catalytic active site (CAS) and the peripheral anionic site (PAS) simultaneously. Based on this novel binding information, 6-ortho-tolylamino and N-ethyl-N-isopropylacetamide substituted piperidine were disclosed as new PAS and CAS binders.

Synthesis and biological evaluation of novel amprenavir-based P1-substituted bi-aryl derivatives as ultra-potent HIV-1 protease inhibitors.

A series of P1-substituted biaryl amprenavir derivatives was designed and synthesized. These compounds were evaluated for enzyme inhibition and antiviral activity in vitro. Several compounds showed highly efficient antiviral activity with EC(50) values down to 0.10nM, which are more potent than marketed HIV-1 protease inhibitors. Docking study indicated that 12c has similar binding mode to amprenavir with full occupancy in P1.