Structural Simplification of Podophyllotoxin: Discovery of γ-Butyrolactone Derivatives as Novel Antiviral Agents for Plant Protection.

Natural products are a valuable resource for the discovery of novel crop protection agents. A series of γ-butyrolactone derivatives, derived from the simplification of podophyllotoxin's structure, were synthesized and assessed for their efficacy against tobacco mosaic virus (TMV). Several derivatives exhibited notable antiviral properties, with compound 3g demonstrating the most potent in vivo anti-TMV activity. At 500 μg/mL, compound 3g achieved an inactivation effect of 87.8%, a protective effect of 71.7%, and a curative effect of 67.7%, surpassing the effectiveness of the commercial plant virucides ningnanmycin and ribavirin . Notably, the syn -diastereomer ( syn - 3g ) exhibited superior antiviral activity compared to the anti -diastereomer ( anti - 3g ). Mechanistic studies revealed that syn - 3g could bind to the TMV coat protein and interfere with the self-assembly process of TMV particles. These findings indicate that compound 3g , with its simple chemical structure, could be a potential candidate for the development of novel antiviral agents for crop protection.