Abstract 13295: Novel Experimental Therapeutics for COVID-19 Derived From a Nitric Oxide Donor

Abstract

Urea transport protein B, the product of the gene SLC14A1 , facilitates transport of urea, water and urea analogues across cell membranes. SLC14A1 mRNA is overexpressed in human vascular endothelial cells in culture under hypoxic (1% oxygen) conditions compared with normoxia. This leads to transport of urea out of the endothelial cell and likely contributes to the reduction in eNOS (endothelial nitric oxide synthase) pathway activity in hypoxia. NO has antiviral activity. Novel compounds were developed by binding a urea-like moiety to the backbone of the generic agent isosorbide mononitrate, a well-known NO donor, to combat vascular endothelial dysfunction in COVID-19, a disease characterized by systemic hypoxia and inflammation due to SARS-CoV-2 infection. A study of drug-protein interactions was undertaken using in silico modelling. Novel compounds were studied against 9 key SARS-CoV-2 targets using Maestro, Schrödinger Suite software (Glide docking). Docking scores and intermolecular interactions within the target’s key binding amino acid residues were studied to compare investigational compounds and known antivirals. Several novel agents tested had a better Glide Score (a prediction of ligand affinity) against the papain-like protease (PL pro ) of SARS-CoV-2 compared with known antiviral drugs. PL pro is considered to be a primary target for therapeutic inhibition of the SARS viruses. The candidate compounds CR-305, CR-607, CR-510 and CR-605 were all superior to Remdesivir, GS-441524, Lopinavir, Boceprevir, and Ribavirin. Given the known direct antiviral action of NO and evidence of specific binding of these compounds to the PL pro of SARS-CoV-2 based on the in silico results, we conclude there is a high likelihood these novel compounds will prove to be of therapeutic value against COVID-19. CR-305 appears to have a higher affinity to SARS-CoV-2 than other antivirals as it sits firmly in the PL pro catalytic pocket and makes the most of key interactions with the catalytic pocket residues: Gly163, Asp164, Gln271 and Tyr264. These data call for a new focus on these novel antiviral agents as they appear to bind with an increased avidity to PL pro (compared with other known antivirals) while targeting delivery of NO to the SARS-CoV-2 virus in COVID-19.