GS-441524 is an antiviral nucleoside analog and the active metabolite of remdesivir. [1] GS-441524 is active against Middle East respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome CoV (SARS-CoV) in infected primary human airway epithelial (HAE) cells (EC50s = 0.86 and 0.18 μM, respectively). It is cytoprotective against hepatitis C virus (HCV), yellow fever virus (YFV), dengue virus type 2 (DENV-2), influenza A, and parainfluenza 3 in cell-based assays (EC50s = 4.1, 11, 9.46, 27.9, and 1.71 μM, respectively).[2]

Reference:
[1]. Agostini, M.L., Andres, E.L., Sims, A.C., et al. Coronavirus susceptibility to the antiviral remdesivir (GS-5734) is mediated by the viral polymerase and the proofreading exoribonuclease. mBio 9(2), e00221-00218 (2018).
[2]. Cho, A., Saunders, O.L., Butler, T., et al. Synthesis and antiviral activity of a series of 1'-substituted 4-aza-7,9-dideazaadenosine C-nucleosides. Bioorg. Med. Chem. 22(8), 2705-2707 (2012).