Biological characterization of AB-343, a novel and potent SARS-CoV-2 M inhibitor with pan-coronavirus activity.

Since the SARS-CoV-2 outbreak, there have been ongoing efforts to identify antiviral molecules with broad coronavirus activity to combat COVID-19. SARS-CoV-2's main protease (M) is responsible for processing the viral polypeptide into non-structural proteins essential for replication. Here, we present the biological characterization of AB-343, a covalent small-molecule inhibitor of SARS-CoV-2 M with potent activity in both cell-based (EC = 0.

Structure-Activity Relationships and Discovery of ()-5-(-Butyl)-11-(difluoromethoxy)-9-methoxy-2-oxo-1,2,5,6-tetrahydropyrido[2',1':2,3]imidazo[4,5-]quinoline-3-carboxylic Acid (AB-161), a Novel Orally Available and Liver-Centric HBV RNA Destabilizer.

Lowering hepatitis B surface antigen (HBsAg) levels from covalently closed circular DNA (cccDNA) and the integrated genome could reduce the persistence of hepatitis B virus (HBV) infection. Since HBV replication occurs in the liver and to ameliorate the peripheral neuropathy observed with a first-generation tricyclic 4-pyridone PAPD5/7 inhibitor () having high systemic exposure, we focused on increasing the hepatocyte concentration and reducing plasma levels. Optimization of a novel series of PAPD5/7 inhibitors that decrease HBsAg levels led to the tetracyclic 2-pyridone , which was similarly potent to and but showed dramatically higher rodent liver-to-plasma ratios.

Rational Design of Macrocyclic Noncovalent Inhibitors of SARS-CoV-2 M from a DNA-Encoded Chemical Library Screening Hit That Demonstrate Potent Inhibition against Pan-Coronavirus Homologues and Nirmatrelvir-Resistant Variants.

The recent global COVID-19 pandemic has highlighted treatments for coronavirus infection as an unmet medical need. The main protease (M) has been an important target for the development of SARS-CoV-2 direct-acting antivirals. Nirmatrelvir as a covalent M inhibitor was the first such approved therapy.

Preclinical Antiviral and Safety Profiling of the HBV RNA Destabilizer AB-161.

HBV RNA destabilizers are a class of small-molecule compounds that target the noncanonical poly(A) RNA polymerases PAPD5 and PAPD7, resulting in HBV RNA degradation and the suppression of viral proteins including the hepatitis B surface antigen (HBsAg). AB-161 is a next-generation HBV RNA destabilizer with potent antiviral activity, inhibiting HBsAg expressed from cccDNA and integrated HBV DNA in HBV cell-based models. AB-161 exhibits broad HBV genotype coverage, maintains activity against variants resistant to nucleoside analogs, and shows additive effects on HBV replication when combined with other classes of HBV inhibitors.

Structure-Activity Relationships and Discovery of ()-6-Isopropyl-2-methoxy-3-(3-methoxypropoxy)-10-oxo-5,10-dihydro-6-pyrido[1,2-][1,7]naphthyridine-9-carboxylic Acid (AB-452), a Novel Orally Available HBV RNA Destabilizer.

Approved therapies for hepatitis B virus (HBV) treatment include nucleos(t)ides and interferon alpha (IFN-α) which effectively suppress viral replication, but they rarely lead to cure. Expression of viral proteins, especially surface antigen of the hepatitis B virus (HBsAg) from covalently closed circular DNA (cccDNA) and the integrated genome, is believed to contribute to the persistence of HBV. This work focuses on therapies that target the expression of HBV proteins, in particular HBsAg, which differs from current treatments.