Discovery of novel phenothiazine derivatives as new agrochemical alternatives for treating plant viral diseases

Abstract

AbstractBackgroundPlant viral diseases, namely ‘plant cancer’, are extremely difficult to control. Even worse, few antiviral agents can effectively control and totally block viral infection. There is an urgent need to explore and discover novel agrochemicals with high activity and a unique mode of action to manage these refractory diseases.ResultsForty‐one new phenothiazine derivatives were prepared and their inhibitory activity against tobacco mosaic virus (TMV) was assessed. Compound A8 had the highest protective activity against TMV, with a half‐maximal effective concentration (EC50) of 115.67 μg/mL, which was significantly better than that of the positive controls ningnanmycin (271.28 μg/mL) and ribavirin (557.47 μg/mL). Biochemical assays demonstrated that compound A8 could inhibit TMV replication by disrupting TMV self‐assembly, but also enabled the tobacco plant to enhance its defense potency by increasing the activities of various defense enzymes.ConclusionIn this study, novel phenothiazine derivatives were elaborately fabricated and showed remarkable anti‐TMV behavior that possessed the dual‐action mechanisms of inhibiting TMV assembly and invoking the defense responses of tobacco plants. Moreover, new agrochemical alternatives based on phenothiazine were assessed for their antiviral activities and showed extended agricultural application. © 2023 Society of Chemical Industry.