TMV-CP based rational design and discovery of α-Amide phosphate derivatives as anti plant viral agents

The tobacco mosaic virus coat protein (TMV-CP) is indispensable for the virus's replication, movement and transmission, as well as for the host plant's immune system to recognize it. It constitutes the outermost layer of the virus particle, and serves as an essential component of the virus structure. TMV-CP is essential for initiating and extending viral assembly, playing a crucial role in the self-assembly process of Tobacco Mosaic Virus (TMV). This research employed TMV-CP as a primary target for virtual screening, from which a library of 43,417 compounds was sourced and SH-05 was chosen as the lead compound. Consequently, a series of α-amide phosphate derivatives were designed and synthesized, exhibiting remarkable anti-TMV efficacy. The synthesized compounds were found to be beneficial in treating TMV, with compound 3g displaying a slightly better curative effect than Ningnanmycin (NNM) (EC₅₀ = 304.54 µg/mL) at an EC₅₀ of 291.9 µg/mL. Additionally, 3g exhibited comparable inactivation activity (EC₅₀ = 63.2 µg/mL) to NNM (EC₅₀ = 67.5 µg/mL) and similar protective activity (EC₅₀ = 228.9 µg/mL) to NNM (EC₅₀ = 219.7 µg/mL). Microscale thermal analysis revealed that the binding of 3g (K_d = 4.5 ± 1.9 µM) to TMV-CP showed the same level with NNM (K_d = 5.5 ± 2.6 µM). Results from transmission electron microscopy indicated that 3g could disrupt the structure of TMV virus particles. The toxicity prediction indicated that 3g was low toxicity. Molecular docking showed that 3g interacted with TMV-CP through hydrogen bond, attractive charge interaction and π-Cation interaction. This research provided a novel α-amide phosphate structure target TMV-CP, which may help the discovery of new anti-TMV agents in the future.