Novel 1,3,4-oxadiazole sulfonate/carboxylate flavonoid derivatives: synthesis and biological activity

Background With the long-term use of traditional bactericides and antiviral agents, drug resistance has become increasingly prominent, resulting in impaired crop growth and yields. Based on this, the introduction of small molecular active groups into natural products has become the direction of research for green pesticides. Results In this study, novel 1,3,4-oxadiazole sulfonate/carboxylate flavonoid derivatives were explored. Among them, D4 exhibited good inhibitory effects on plant bacteria. It is worth mentioning that D4 (15 mu g ml(-1)) exhibited an excellent median effective concentration (EC50) value against Xanthomonas oryzae pv. oryzae (Xoo), which was better than bismerthiazol (73 mu g ml(-1)) and thiodiazole copper (100 mu g ml(-1)). The EC50 for D4 was much lower than the two positive controls (bismerthiazol, thiodiazole copper), making D4 more potent in this assay of bacterial growth inhibition. In addition, mechanism research using scanning electron microscopy revealed that D4 could cause deformation or rupture of the cell membranes of Xoo and Pseudomonas syringae pv. actinidiae. Moreover, D4 exhibited the best EC50 for in vivo curative (132 mu g ml(-1)) and protective (101 mu g ml(-1)) activities against tobacco mosaic virus, which were more effective than ningnanmycin. Microscale thermophoresis data suggested that D4 [dissociation constant (K-d) = 0.038 +/- 0.011 mu mol L-1] exhibited a stronger binding capacity than the control agent ningnanmycin (K-d = 4.707 +/- 2.176 mu mol L-1). Conclusion The biological activity data and mode of action demonstrated that D4 had the best antibacterial and antiviral effects. Compound D4 discovered in the current work may be a very promising agricultural drug. (c) 2022 Society of Chemical Industry.

Automated summary

The 1,3,4-oxadiazole sulfonate/carboxylate flavonoid derivatives, specifically D4, demonstrated excellent antibacterial and antiviral effects. Through scanning electron microscopy, it was found that D4 could cause deformation or rupture of bacterial cell membranes. Additionally, D4 exhibited remarkable in vivo curative and protective activities against tobacco mosaic virus. Microscale thermophoresis data indicated that D4 had a stronger binding capacity compared to the control agent ningnanmycin.