Synthesis, Antiviral Activity, and Induction of Plant Resistance of Indole Analogues Bearing Dithioacetal Moiety

A series of compounds with potential activity to induce
plant resistance
was synthesized from indole and thiol compounds and methodically evaluated
for antiviral activity. The results indicated that some of the synthesized
compounds had high antipotato virus Y (PVY), anticucumber mosaic virus,
and antitobacco mosaic virus activities. Notably, compound D21 exhibited the best activity against PVY among these compounds in
vivo, and the 50% effective concentrations (EC50) of protection
activity is 122 μg/mL, which was distinctively better than the
corresponding values for ribavirin (653 μg/mL), Ningnanmycin
(464 μg/mL), and Xiangcaoliusuobingmi (279 μg/mL). Interestingly,
we found that the protection activity of D21 was associated
with improvement of chlorophyll content and defense-related enzyme
activities. Moreover, D21 could trigger the malate dehydrogenase
(MDH) signaling pathway, as further confirmed by the MDH activity
evaluation. Hence, D21 can protect plants against viral
activity and has potential as a novel activator for plant resistance
induction.