Discovery of Clioquinol and Analogues as Novel Inhibitors of Severe Acute Respiratory Syndrome Coronavirus 2 Infection, ACE2 and ACE2 - Spike Protein Interaction In Vitro

Abstract

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the etiological agent for coronavirus disease 2019 (COVID-19), has emerged as an ongoing global pandemic. Presently, there are no clinically approved vaccines nor drugs for COVID-19. Hence, there is an urgent need to accelerate the development of effective antivirals. Here in, we discovered Clioquinol (5-chloro-7-iodo-8-quinolinol (CLQ)), a FDA approved drug and two of its analogues (7-bromo-5-chloro-8-hydroxyquinoline (CLBQ14); and 5, 7-Dichloro-8-hydroxyquinoline (CLCQ)) as potent inhibitors of SARS-CoV-2 infection induced cytopathic effect in vitro. In addition, all three compounds showed potent anti-exopeptidase activity against recombinant human angiotensin converting enzyme 2 (rhACE2) and inhibited the binding of rhACE2 with SARS-CoV-2 Spike (RBD) protein. CLQ displayed the highest potency in the low micromolar range, with its antiviral activity showing strong correlation with inhibition of rhACE2 and rhACE2-RBD interaction. Altogether, our findings provide a new mode of action and molecular target for CLQ and validates this pharmacophore as a promising lead series for clinical development of potential therapeutics for COVID-19.

Ambroxol Hydrochloride Inhibits the Interaction between Severe Acute Respiratory Syndrome Coronavirus 2 Spike Protein’s Receptor Binding Domain and Recombinant Human ACE2

“…However, the IC 50 of Aloxistatin (21.78 µM) was similar to that of BHH (21.72 µM) ( Table 1 and 2). The IC 50 values that we observed for the reference compounds are consistent with earlier reports [44][45][46][47] . While writing this manuscript, we found that other cellular studies tested BHH and AMB at certain or single concentrations [48][49][50] ; however, this is the first study to our knowledge to conduct the IC 50 evaluation for BHH and AMB against the novel SARS-CoV-2 infection induced CPE.…”

Rapid and Sensitive Inhibitor Screening Using Magnetically Modulated Biosensors

“…Here, the inhibitory effect of DMSO is seen at concentrations of 5-50% v/v (Figure 5a). Currently, low concentrations of DMSO (0.3-0.5% v/v) [5,46] are commonly used as a negative control for SARS-CoV-2 inhibitor screening experiments [9,47]. Therefore, to test the inhibitory effect of the small molecule SSAA09E2 on the S1-ACE2 interaction, a constant low concentration of 1% v/v DMSO, which, according to our results, does not inhibit the interaction itself, was used.…”

“…The outbreak of coronavirus disease in 2019 (COVID-19) started a race to develop drugs to treat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Such drug development usually requires the identification of inhibitors (e.g., therapeutic antibodies, peptides, and small molecules) that inhibit the activity of the virus [1][2][3][4][5][6][7][8]. In general, a virus infection cycle includes several phases, such as adhesion, viral entry, endocytosis, replication, and virus release [3].…”

Evolutionary analysis of SARS‐CoV‐2 spike protein for its different clades

“…In fact, more than 200 candidates for vaccines against SARS‐CoV‐2 and several antivirals are already being developed 7,8 . Most of the vaccines and therapeutic drugs are directed towards the spike glycoprotein (S) that is responsible for entering the host cell through recognition of the receptor ACE2 with the receptor‐binding protein (RBD) 8–12 . Therefore, knowing the evolutionary rate of the S is relevant as changes in this protein could affect the efficacy of the vaccine and the antivirals directed to S. Even though some studies have determined the nucleotide evolutionary rate of SARS‐CoV‐2 using the entire genome, 13,14 those values are slower and do not represent the real mutation capacity of the S region alone.…”