Lycorine Derivative Inhibits SARS-CoV-2 Replication by Reducing -1 Programmed Ribosomal Frameshifting via Targeting ZAP.

The ongoing evolution of SARS-CoV-2 and its immune-evading variants underscores an urgent requirement for broad-spectrum antiviral drugs. In this study, a series of lycorine derivatives was synthesized. This led to the identification of compound 7 as a promising antiviral candidate. Compound 7 exhibited potent inhibitory activity against SARS-CoV-2 and its variants, including Alpha, Beta, Delta, and Omicron, in vitro. The antiviral efficacy of compound 7 was then validated in vivo. Treatment with compound 7 significantly reduced viral loads and alleviated lung pathologies in SARS-CoV-2-infected hamsters. Mechanistically, compound 7 directly targeted the short isoform of the zinc-finger antiviral protein (ZAP-S) and bound to specific residues (E111, E115, and F549). This result was confirmed using cellular thermal shift assays, bio-layer interferometry, and mutagenesis studies. This interaction enhanced the ZAP-S stability and disrupted -1 programmed ribosomal frameshifting (-1PRF), a critical process for viral polyprotein synthesis. The antiviral activity of compound 7 was ZAP-S-dependent, as ZAP-S knockdown abolished its efficacy while overexpression enhanced it. These results established compound 7 as a novel antiviral candidate that can combat SARS-CoV-2 and its variants by targeting ZAP to inhibit -1PRF. This compound, therefore, represents a promising therapeutic strategy.