Gold complexes have al ong tradition in medicine and for many examples antirheumatic, anticancer or anti-infective effectsh ave been confirmed. Herein,w e evaluated the lead compound Auranofin and five selected gold organometallics as inhibitors of two relevant drug targetso fs evere acute respiratory syndrome coronaviruses (SARS-CoV). The gold metallodrugsw ere effectivei nhibitorso ft he interaction of the SARS-CoV-2 spike protein with the angiotensin converting enzyme 2(ACE2) host receptor and might thusi nterfere with the viral entry process. The gold metallodrugsw ere also efficient inhibitors of the papain-like protease (PLpro) of SARS-CoV-1 and SARS-CoV-2, which is ak ey enzymei nt he viral replication. Regarding PLpro from SARS-CoV-2,t he here reportedi nhibitorsa re among the very first experimentally confirmed examples with activity against this target enzyme. Importantly,t he activity of the complexes against both PLpro enzymes correlated with the ability of the inhibitors to removez inc ions from the labile zinc center of the enzyme. Ta ken together,the results of this pilot study suggest further evaluation of gold complexes as SARS-CoV antiviral drugs.

The global spread of the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has called for an urgent need for dedicated antiviral therapeutics. Metal complexes are commonly underrepresented in compound libraries that are used for screening in drug discovery campaigns, however, there is growing evidence for their role in medicinal chemistry. Based on previous results, we have selected more than 100 structurally diverse metal complexes for profiling as inhibitors of two relevant SARS‐CoV‐2 replication mechanisms, namely the interaction of the spike (S) protein with the ACE2 receptor and the papain‐like protease PL pro . In addition to many well‐established types of mononuclear experimental metallodrugs, the pool of compounds tested was extended to approved metal‐based therapeutics such as silver sulfadiazine and thiomersal, as well as polyoxometalates (POMs). Among the mononuclear metal complexes, only a small number of active inhibitors of the S/ACE2 interaction was identified, with titanocene dichloride as the only strong inhibitor. However, among the gold and silver containing complexes many turned out to be very potent inhibitors of PL pro activity. Highly promising activity against both targets was noted for many POMs. Selected complexes were evaluated in antiviral SARS‐CoV‐2 assays confirming activity for gold complexes with N‐heterocyclic carbene (NHC) or dithiocarbamato ligands, a silver NHC complex, titanocene dichloride as well as a POM compound. These studies might provide starting points for the design of metal‐based SARS‐CoV‐2 antiviral agents.

Gold complexes have a long tradition in medicine and for many examples antirheumatic, anticancer or anti-infective effects have been confirmed. Here we evaluated the lead compound Auranofin and five selected gold organometallics as inhibitors of two relevant drug targets of severe acute respiratory syndrome coronaviruses (SARS-CoV). The gold metallodrugs were effective inhibitors of the interaction of the SARS-CoV-2 spike protein with the angiotensin converting enzyme 2 (ACE2) host receptor and might thus interfere with the viral entry process. The gold metallodrugs were also efficient inhibitors of the SARS-CoV-1 papain-like protease (PLpro), which is a key enzyme in the viral replication. Taken together, the results of this pilot study suggest further evaluation of gold complexes as SARS-CoV antiviral drugs.