Targeting dihydroorotate dehydrogenase (DHODH) for host-directed therapy: Discovery of a novel alkyne-based scaffold inhibitor effective against SARS-CoV-2.

In response to the rising challenge of pathogen resistance to anti-infective therapies, innovative approaches such as host-directed therapy are being investigated to bypass these resistance mechanisms. Dihydroorotate dehydrogenase (DHODH) is a crucial enzyme for synthesizing pyrimidines, which are essential for RNA and DNA biosynthesis. Inhibiting DHODH can deplete the nucleotide pool, thereby impairing the replication of pathogens that depend on this pathway. In this study, we evaluated a library of fragment-like compounds against human DHODH (HsDHODH) and identified a 1,2-diarylethine scaffold as a potential new inhibitor. Utilizing the predicted binding mode and the activity of fragments 3a and 3l against HsDHODH, we designed and synthesized 14 novel diarylethine derivatives focused on improving their potency against the enzyme. The activity of the most potent compound (3e, IC50 1.50 ± 0.02 μM) was translated to antiviral activity against SARS-CoV-2 in infected Calu-3 cells (EC50 1.7 ± 0.5 μM), with low cytotoxicity. Early ADME in vitro evaluation indicated a need for improved solubility, which will be addressed in subsequent multi-parameter optimization efforts. These findings pave the way for developing novel HsDHODH inhibitors with enhanced pharmacological and pharmacokinetics profiles, offering a promising strategy to address viral diseases that are resistant to conventional treatments.