Design, Synthesis, Antiviral Bioactivity, and Defense Mechanisms of Novel Dithioacetal Derivatives Bearing a Strobilurin Moiety

A series of dithioacetal derivatives
bearing a strobilurin moiety
were designed and synthesized on the basis of our previous work. The
antiviral activities of these compounds against Potato virus Y (PVY),
Cucumber mosaic virus (CMV), and Tobacco mosaic virus (TMV) were systematically
evaluated. Bioassay results indicated that C14 elicited
excellent curative and protective activities against PVY, CMV, and
TMV. The former had 50% effective concentrations (EC50)
of 125.3, 108.9, and 181.7 μg/mL, respectively, and the latter
had 148.4, 113.2, and 214.6 μg/mL, respectively, which were
significantly superior to those of lead compound 6f (297.6,
259.6, and 582.4 μg/mL and 281.5, 244.3, and 546.3 μg/mL,
respectively), Ningnanmycin (440.5, 549.1, and 373.8 μg/mL and
425.3, 513.3, and 242.7 μg/mL, respectively), Chitosan oligosaccharide
(553.4, 582.8, and 513.8 μg/mL and 547.3, 570.6, and 507.9 μg/mL,
respectively), and Ribavirin (677.4, 690.3, and 686.5 μg/mL
and 652.7, 665.4, and 653.4 μg/mL, respectively). Moreover,
defensive enzyme activities and RT-qPCR analysis demonstrated that
the antiviral activity was associated with the changes of SOD, CAT,
and POD activities in tobacco, which was proved by the related proteins
of abscisic acid signaling pathway. This work provided a basis for
further design, structural modification, and development of dithioacetal
derivatives as new antiviral agents.