Synthesis and antibacterial activity of oxime ester derivatives containing 1,2,4-triazole or 1,3,4-oxadiazole moiety

A series of oxime ester derivatives containing 1,2,4-triazole or 1,3,4-oxadiazole moiety were designed and synthesized, and their antibacterial activities in vitro against Xanthomonas axonopodis pv. citri (Xac) and Xanthomonas oryzae pv. oryzae (Xoo) were evaluated. The bioassays showed that all the title compounds exhibit potent antibacterial activity against Xac and Xoo. In particular, the compounds 4a, 5a, 5b, 5c, 5d, 5h and 5i exhibited remarkable antibacterial activity against Xoo, with the EC50 values ranging from 15.15 to 49.34 mu g/mL, which were superior to that of bismerthiazol (92.61 mu g/mL). This study indicated that oxime ester derivatives containing 1,2,4-triazole or 1,3,4-oxadiazole moiety may be used as potential alternative templates in the search for novel antibacterial agents.