The diffusion of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a pandemic with
unprecedent socioeconomical impact, enlightening the need of new antiviral agents able to block viral
replication. The development of vaccines is essential in the containment of the diffusion of the virus, and an
incredible joint effort led to a global vaccination campaign in about 1 year after the virus outbreak. However,
vaccines may be less or no effective against emerging variants of SARS-CoV-2 and, also, it is still unknown how
long this vaccine-induced immunity will last. Therefore, the development of antiviral drugs against
SARS-CoV-2 is of pivotal importance.
The SARS-CoV-2 non-structural protein 13 (nsp13) has been identified as a target for antiviral drugs thanks to
its critical role in viral replication and to its high sequence conservation within the coronavirus family. Nsp13
targets the natural nucleotides and deoxynucleotides as substrates when performing its adenosine triphosphatase
(ATPase) activity, utilizing the energy of nucleotide triphosphate hydrolysis to catalyze the unwinding of
double-stranded DNA or RNA in a 5′ to 3′ direction.
Although the roles of nsp13 in the viral lifecycle, there is a paucity of information about small molecules
compounds reported in literature endowed with nsp13-inhibitory activity. Aryl diketo acids (DKAs) have been
previously described as inhibitors of nsp13 of SARS-CoV-1. Basing on these literature data and thanks to our
longstanding expertise in the design and synthesis of DKA derivatives, we carried out a semi-random screening
on our in-house library of DKA compounds, identifying a promising hit compound as micromolar nsp13
inhibitor. We synthesized a set of indolyl DKA derivatives as structurally correlated with the identified hit,
obtaining new dual SARS-CoV-2 nsp13 ATPase and helicase inhibitors, also capable of inhibiting viral
replication. Mode-of-action studies revealed ATP-non-competitive kinetics of inhibition, not affected by
substrate-displacement effect, suggesting an allosteric binding. The data coming from the biological assays will
be shown and discussed
