Amantadine inhibits known and novel ion channels encoded by SARS-CoV-2 in vitro
Trine L. Toft‐Bertelsen, Mads Gravers Jeppesen, Eva Tzortzini, Kai Xue, Karin Giller, Stefan Becker, Amer Mujezinovic, Bo Hjorth Bentzen, Loren B. Andreas, Antonios Kolocouris, Thomas N. Kledal, Mette M. Rosenkilde
Abstract
The dire need for COVID-19 treatments has inspired strategies of repurposing approved drugs. Amantadine has been suggested as a candidate, and cellular as well as clinical studies have indicated beneficial effects of this drug. We demonstrate that amantadine and hexamethylene-amiloride (HMA), but not rimantadine, block the ion channel activity of Protein E from SARS-CoV-2, a conserved viroporin among coronaviruses. These findings agree with their binding to Protein E as evaluated by solution NMR and molecular dynamics simulations. Moreover, we identify two novel viroporins of SARS-CoV-2; ORF7b and ORF10, by showing ion channel activity in a X. laevis oocyte expression system. Notably, amantadine also blocks the ion channel activity of ORF10, thereby providing two ion channel targets in SARS-CoV-2 for amantadine treatment in COVID-19 patients. A screen of known viroporin inhibitors on Protein E, ORF7b, ORF10 and Protein 3a from SARS-CoV-2 revealed inhibition of Protein E and ORF7b by emodin and xanthene, the latter also blocking Protein 3a. This illustrates a general potential of well-known ion channel blockers against SARS-CoV-2 and specifically a dual molecular basis for the promising effects of amantadine in COVID-19 treatment. We therefore propose amantadine as a novel, cheap, readily available and effective way to treat COVID-19.