SuFEx-Enabled High-Throughput Medicinal Chemistry for Developing Potent Tamoxifen Analogs as Ebola Virus Entry Inhibitors

Lucas Dada ¹ Emiko Nagai ¹ Sashank Agrawal ² Ariel S Wirchnianski ¹ Ian A Wilson ² Kartik Chandran ² Seiya Kitamura ^1*

• ¹ Albert Einstein College of Medicine, New York City, United States
• ² The Scripps Research Institute, La Jolla, California, United States

Ebola virus (EBOV) causes severe hemorrhagic fever with a high mortality rate in humans. In acute infection, an abnormal immune response results in excessive inflammatory cytokines and uncontrolled systemic inflammation that can result in organ damage and multi-organ failure. While vaccines and monoclonal antibody therapies are available, there is an urgent need for effective small-molecule antivirals against EBOV. Here, we report on the optimization of tamoxifen, an EBOV-glycoprotein (GP) binder that inhibits viral entry, using our Sulfur-Fluoride Exchange (SuFEx) click chemistrybased high-throughput medicinal chemistry (HTMC) strategy. Using a "Direct-to-Biology" approach, we generated a focused library of 2,496 tamoxifen analogs overnight and screened them in a cell-based pseudo-EBOV infection assay. The HTMC workflow enabled the development of a potent EBOV entry inhibitor with submicromolar EC50 cellular antiviral activity and more than 50-fold improvement in binding affinity against EBOV-GP compared to the parent compound. Our findings underscore the use of SuFEx-enabled HTMC for rapidly generating and assessing potential therapeutic candidates against viral and immune-mediated diseases in a cell-based assay.