Optimization, Structure-Activity Relationship, and Mode of Action of Nortopsentin Analogues Containing Thiazole and Oxazole Moieties.

Plant diseases seriously endanger plant health, and it is very difficult to control them. A series of nortopsentin analogues were designed, synthesized, and evaluated for their antiviral activities and fungicidal activities. Most of these compounds displayed higher antiviral activities than ribavirin. Compounds 1d, 1e, and 12a, with excellent antiviral activities, emerged as novel antiviral lead compounds, among which 1e was selected for further antiviral mechanism research. The mechanism research results indicated that these compounds may play an antiviral role by aggregating viral particles to prevent their movement in plants. Further fungicidal activity tests revealed that nortopsentin analogues displayed broad-spectrum fungicidal activities. Compounds 2p and 2f displayed higher antifungal activities against Alternaria solani than the commercial fungicides carbendazim and chlorothalonil. Current research has laid a foundation for the application of nortopsentin analogues in plant protection.