Inhibition of hepatitis B virus replication by N -hydroxyisoquinolinediones and related polyoxygenated heterocycles

Abstract

We previously reported low sensitivity of the hepatitis B virus (HBV) ribonuclease H (RNaseH) enzyme to inhibition by N-hydroxyisoquinolinedione (HID) compounds. Subsequently, our biochemical RNaseH assay was found to have a high false negative rate for predicting HBV replication inhibition, leading to underestimation of the number of HIDs that inhibit HBV replication. Here, 39 HID compounds and structurally related polyoxygenated heterocycles (POH), N-hydroxypyridinediones (HPD), and flutimides were screened for inhibition of HBV replication in vitro. Inhibiting the HBV RNaseH preferentially blocks synthesis of the positive-polarity DNA strand and causes accumulation of RNA:DNA heteroduplexes. Eleven HIDs and one HPD preferentially inhibited HBV positive-polarity DNA strand accumulation. EC50s ranged from 0.69 μM to 19 μM with therapeutic indices from 2.4 – 71. Neither the HIDs nor the HPD had an effect on the ability of the polymerase to elongate DNA strands in capsids. HBV RNaseH inhibition by the HIDs was confirmed with an improved RNaseH assay and by detecting accumulation RNA:DNA heteroduplexes in HBV capsids from cells treated with a representative HID. Therefore, the HID scaffold is more promising for anti-HBV drug discovery than we originally reported, and the HPD scaffold may hold potential for antiviral development. The preliminary structure-activity relationship will guide optimization of the HID/HPDs as HBV inhibitors.

Marine Algal Antioxidants as Potential Vectors for Controlling Viral Diseases

“…In particular, an alginate named 911 exhibited promising activity against HIV-1 decrementing the activity of reverse transcriptase (RTase), discontinuing the virus adsorption, and immunostimulating the host cells [72]. Alternative inhibitory results were also reported against the hepatitis B virus (HBV), where 911 alginate could inhibit the virus replication by suppressing the activity of DNA polymerase [73]. Furthermore, the sulfated polymannuroguluronate (SPMG) is a promising anti-AIDS drug candidate, inhibiting the robust attachment of HIV-1 gp120 protein with CD4 molecules on the surface of T cells [74].…”

Efficacy and cytotoxicity in cell culture of novel α-hydroxytropolone inhibitors of hepatitis B virus ribonuclease H

“…However, all currently approved direct-acting anti-HBV drugs are RT inhibitors, whereas RNaseH inhibitors are yet to be developed. Recently we identified several classes of compounds that effectively inhibit both HBV RNaseH activity and viral replication (Cai et al, 2014; Edwards et al, 2017; Hu et al, 2013; Lu et al, 2015; Tavis et al, 2013). Many of the best inhibitors are α-hydroxytropolones (Lu et al, 2015).…”

Meeting report: 31st International Conference on Antiviral Research

“…Tiffany Edwards of Saint Louis University, MO, USA, reported the development of HBV RNaseH inhibitors belonging to either the N-hydroxy-isoquinolinedione (HID) and N-hydroxy-pyridinedione (HPD) families. This work follows published efforts of this team to improve the efficacy and characterize the anti-RNAse activity of these compounds in vitro (Edwards et al, 2017;Lomonosova et al, 2017). As a recall, RNAse activity in HBV polymerase is crucial for the reverse transcription of pregenomic RNA into rcDNA within nucleocapsids.…”