Synthesis and anti-SARS-CoV-2 activity and mechanism research of lycorine derivatives

We designed and synthesized eighteen lycorine derivatives with five different structural types, and evaluated their antiviral activities on a HCoV-OC43-infected H460 cell model. Structure-activity relationships suggested that the introduction of appropriate substituents on the 6N atom of lycorine was beneficial to activity. Compound 6a gave a good activity with the half effective concentration (EC₅₀) and selectivity index (SI) values of 2.36 μmol·L^-1 and 16.52, respectively. Surface plasmon resonance (SPR) result indicated that 6a might target the non-structural protein 12 (NSP12) subunit in RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 with the dissociation constant (K_D) value of 1.36 μmol·L^-1. Molecular docking indicated that 6a might act on nidovirus RdRp-associated nucleotidyltransferase (NiRAN) catalytic center of NSP12, distinct from the mechanism of nucleoside-like drugs such as remdesivir. This study provides scientific data for the development of lycorine derivatives into a new class of anti-SARS-CoV-2 small molecule inhibitors.