Design, Synthesis and Antimicrobial Behaviors of Novel Oxadiazoles Owning Various N‐Containing Heterocyclic Pendants

BACKGROUND: The gradually elevated outbreak of plant bacterial diseases severely limits agricultural products and small amounts of pesticides can manage them. Our group has previously synthesized and screened the antimicrobial activity of diverse 1,3,4-oxadiazole thioether/sulfone compounds bridged by a sulfur atom at the 2-position of 1,3,4-oxadiazole. However, few studies evaluated the effect of eliminating the sulfur atom on bioactivity. Herein, a novel type of N-containing heterocyclic pendants-tagged 1,3,4-oxadiazoles bridged by alkyl chains only was systematically synthesized and evaluated for their antimicrobial activities. RESULTS: Bioassay results revealed that antibacterial efficacy increased by 551- and 314-folds against the corresponding phytopathogens Xanthomonas oryzae pv. oryzae and X. axonopodis pv. citri comparing to those of commercial agents. In vivo trials showed that C1 exerted remarkable curative activity against rice bacterial blight with the control effectiveness of 52.9% at 200 mug/mL. Antibacterial mechanism research found that C1 could reduce the hypersensitive response behavior and pathogenicity of Xoo through targeting the type III secretion systems (T3SS) at a lower drug dose. This outcome was verified by those observed significantly down-regulated proteins and representative genes from the related quantitative proteomics and qRT-PCR assays. CONCLUSION: This study can inspire the design of innovative molecular frameworks targeting T3SS of phytopathogens for controlling bacterial infections. This article is protected by copyright. All rights reserved.