Identification of natural Rutaecarpine as a potent tobacco mosaic virus (TMV) helicase candidate for managing intractable plant viral diseases.

Background: Naturally occurring alkaloids are particularly suitable for use as pesticide precursors and further modifications due to their cost-effectiveness, unique mechanism of action, tolerable degradation, and environmental friendliness. The famous tobacco mosaic virus (TMV) is a persistent plant pathogenic virus that can parasitize many plants and severely reduce crop production. To treat TMV disease, TMV helicase acts as a crucial target by hydrolyzing adenosine triphosphate (ATP) to provide energy for double-stranded RNA unwinding.

Results: To seek novel framework alkaloid leads targeting TMV helicase, this work successfully established an efficient screening platform for TMV helicase inhibitors based on natural alkaloids. In vivo activity screening, enzyme activity detection, and binding assays showed that Rutaecarpine from Evodia rutaecarpa (Juss.) Benth exhibited excellent TMV helicase inhibitory properties [dissociation constant (K ) = 1.1 μm, half maximal inhibitory concentration (IC ) = 227.24 μm] and excellent anti-TMV ability. Molecular docking and dynamic simulations depicted that Rutaecarpine could stably bind in active pockets of helicase with low binding energy (ΔG  = -17.8 kcal/mol) driven by hydrogen bonding and hydrophobic interactions.

Conclusion: Given Rutaecarpine's laudable bioactivity and structural modifiability, it can serve as a privileged building block for further pesticide discovery.