N-Naphthoyl-substituted indole thio-barbituric acid analogs inhibit the helicase activity of the hepatitis C virus NS3. Issue 3 (1st February 2019)

• Record Type: Journal Article
• Authors: Marecki, John C.; Aarattuthodiyil, Suja; Byrd, Alicia K.; Penthala, Narsimha R.; Crooks, Peter A.; Raney, Kevin D.
• Is Part Of: Bioorganic & medicinal chemistry letters. Volume 29:Issue 3(2019)
• Page Start: 430
• Page End: 434
• Publication Date: 2019-02-01
• Subjects: NS3 nonstructural protein 3 -- HCV hepatitis C virus -- ITBA indole thio-barbituric acid -- ssDNA single-stranded DNA -- dsDNA double-stranded DNA -- DMSO dimethylsulfoxide -- FAM 6-carboxyfluoroscein; Helicase -- Hepatitis C virus -- Nonstructural protein 3 -- Thio-barbituric acid; Bioorganic chemistry -- Periodicals; Pharmaceutical chemistry -- Periodicals; 572
• DOI: 10.1016/j.bmcl.2018.12.026
• Languages: English
• ISSNs: 0960-894X

Abstract

Graphical abstract: Highlights: Hepatitis C Virus NS3 helicase activity is inhibited by N -naphthoyl-containing indole thio-barbituric acid analogs. Both RNA and DNA-dependent unwinding activities of NS3 helicase are inhibited. Nucleic acid binding, protease and ATPase activities are not inhibited by the compounds. Abstract: The hepatitis C virus (HCV) represents a substantial threat to human health worldwide. The virus expresses a dual-function protein, NS3 having both protease and RNA helicase activities that are essential for productive viral replication and sustained infections. While viral protease and polymerase inhibitors have shown great successes in treating chronic HCV infections, drugs that specifically target the helicase activity have not advanced. A robust and quantitative 96-well plate-based fluorescent DNA unwinding assay was used to screen a class of indole thio-barbituric acid (ITBA) analogs using the full-length, recombinant HCV NS3, and identified three naphthoyl-containing analogs that efficiently inhibited NS3 helicase activity in a dose-dependent manner, with observed IC50 values of 21–24 µM. Standard gel electrophoresis helicase assays using radiolabeled duplex DNA and RNA NS3 substrates confirmed the inhibition of NS3 unwinding activity. Subsequent anisotropy measurements demonstrated that the candidate compounds did not disrupt NS3 binding to nucleic acids. Additionally, the rate of ATP hydrolysis and the protease activity were also not affected by the inhibitors. Thus, these results indicate that the three ITBA analogs containing N -naphthoyl moieties are the foundation of a potential series of small molecules capable of inhibiting NS3 activity via a novel interaction with the helicase domain that prevents the productive unwinding of nucleic acid substrates, and may represent the basis for a new class of therapeutic agents with the potential to aid in the treatment and eradication of hepatitis C virus.