Biological activity evaluation and action mechanism of chalcone derivatives containing thiophene sulfonate

A series of novel chalcone derivatives containing a thiophene sulfonate group were designed and synthesized. The structures of all title compounds were determined by ¹H-NMR, ¹³C-NMR and HRMS. Antibacterial bioassays indicated that, compound 2l demonstrated excellent antibacterial activities against Xanthomonas axonopodis pv. citri (Xac), with an EC₅₀ value of 11.4 μg mL^-1, which is significantly superior to those of bismerthiazol (BT) (51.6 μg mL^-1) and thiodiazole-copper (TC) (94.7 μg mL^-1). Meanwhile, the mechanism of action of compound 2l was confirmed by using scanning electron microscopy (SEM). In addition, compound 2e showed remarkable inactivation activity against Tobacco mosaic virus (TMV), with an EC₅₀ value of 44.3 μg mL^-1, which was superior to that of ningnanmycin (120.6 μg mL^-1). Microscale thermophoresis (MST) also showed that the binding of compounds 2e and 2h to Tobacco mosaic virus coat protein (TMV-CP) yielded K _d values of 0.270 and 0.301 μmol L^-1, which are better than that of ningnanmycin (0.596 μmol L^-1). At the same time, molecular docking studies for 2e and 2h with TMV-CP (PDB code: 1EI7) showed that the compound was embedded well in the pocket between the two subunits of TMV-CP in each case. These results suggested that chalcone derivatives containing a thiophene sulfonate group may be considered as activators in the design of antibacterial and antiviral agents.