Design, synthesis and antibacterial activities against Xanthomonas oryzae pv. oryzae, Xanthomonas axonopodis pv. Citri and Ralstonia solanacearum of novel myricetin derivatives containing sulfonamide moiety.

Background: Myricetin and sulfonamide derivatives exhibited a wide variety of biological activity. In order to develop highly bioactive molecules, novel myricetin derivatives containing sulfonamide moiety were synthesized and antibacterial activities were investigated.

Results: The results of bioassays indicated that compound A12, having an EC value of 4.7 μg mL , exhibited the best in vitro antibacterial activities against Xanthomonas oryzae pv. oryzae (X. oryzae pv. o.); EC values for this compound were even better than those of thiodiazole-copper (TC, 71.4 μg mL ) and bismerthiazol (BT, 54.7 μg mL ). Compound A2, having an EC value of 1.1 μg mL , exhibited the best in vitro antibacterial activities against Xanthomonas axonopodis pv. citri (X. axonopodis pv. c); values were notably better than those of TC (60.0 μg mL ) and BT (48.9 μg mL ). Scanning electron microscopy analysis indicated that compounds A2 and A12 caused the cell membranes of X. axonopodis pv. c and X. oryzae pv. o. to break or deform, respectively. When the concentration of compound A12 was 100 μg mL , the effective curative activity against bacterial leaf blight of rice was 44.2% in vivo and the effective protection activity was 58.2% in vivo, results that were both better than values for TC (18.9 and 21.4%, respectively) and BT (12.5 and 12.5%, respectively).

Conclusion: Novel myricetin derivatives containing a sulfonamide moiety were synthesized and bioassay results showed that compounds A2 and A12 exhibited the best antibacterial activities. © 2019 Society of Chemical Industry.