Synthesis and biological evaluation of 1,4-pentadien-3-one derivatives containing 1,2,4-triazole

A series of new 1,4-pentadien-3-one derivatives containing 1,2,4-triazole moiety were synthesized. The structures of the synthesized compounds were charactered via 1H NMR, 13C NMR and HRMS. Antibacterial bioassays indicated that some of compounds showed potential antibacterial activities against Ralstonia solanacearum (Rs), Xanthomonas oryzae pv. Oryzae (Xoo) and Xanthomonas axonopodis pv. Citri (Xac). Compounds F8 and F17 showed good in vitro antibacterial activities against Rs, with the EC50 values of 18.6 and 18.6 μg/mL, respectively, which were better than commercial agent bismerthiazol (55.2 μg/mL). Furthermore, compounds F12 and F15 showed good in vitro antibacterial activities against Xoo, with the EC50 values of 10.9 and 17.5 μg/mL, which were better than commercial agent bismerthiazol (69.3 μg/mL). Moreover, compounds F2, F9, F16 and F17 showed good in vitro antibacterial activities against Xac, with the EC50 values of 6.6, 5.4, 7.5 and 7.8 μg/mL, respectively, which were better than commercial agent bismerthiazol (54.9 μg/mL). The effect of compound F9 on Xac bacterial cell membrane rupture was observed by scanning electron microscopy (SEM). In addition, antiviral bioassays indicated that some of compounds showed excellent protection activities against tobacco mosaic virus (TMV). Compounds F5 and F15 showed good protecting activity against TMV, with the EC50 values of 108.3 and 105.4 μg/mL, respectively, which were better than commercial agent ningnanmycin (214.7 μg/mL). Microscale thermophoresis (MST) also showed that the binding of compound F2 to TMV coat protein (TMV-CP) yielded a Kd value of 1.260 ± 0.654 μmol/L, which was very close to ningnanmycin (1.058 ± 0.286 μmol/L). Similarly, the molecular docking studies for F2 and F5 with TMV-CP (PDB code: 1EI7, ID: 4QGH) indicated that compounds F2 and F5 had partially interacted with TMV-CP.