Background: Chemical fungicides are the mainstay of plant disease control in agricultural production, but there are a very limited number of drugs that can effectively control plant diseases. Two series of secondary amine derivatives were synthesized using the diamine skeleton combined with saturated aromatic and aliphatic aldehydes, and their antibacterial and antifungal activities against plant pathogens were determined. In addition, the antimicrobial mechanism of the highly active compound A26 was preliminarily examined against Xanthomonas oryzae (Xoo).
Results: Compound A26 exhibited the highest antibacterial potency among all the target compounds, with MIC values of 3.12, 3.12 and 12.5 μg mL-1 against Xoo, Xanthomonas axonopodis pv. Citri and Pseudomonas sollamacearum, respectively. In addition, compound A26 had powerful curative and protective effects against Xoo at 200 μg mL-1 , and was better than the control agent Xinjunan. Preliminary mechanistic studies showed that compound A26 reduced the bacterial pathogenicity by targeting cell membranes and inhibiting the secretion of extracellular polysaccharides. Meanwhile, the toxicity of compound A26 to Human Embryonic Kidney 293 cells and Human Liver-7702 was similar to that of Xinjunan, and it had moderate toxicity according to the World Health Organization classification standard of oral exogenous toxicity, with an LD50 of 245.47 mg kg-1 .
Conclusion: Secondary amines have efficient and broad-spectrum antibacterial activity against plant pathogenic bacteria and are expected to be a new class of candidate compounds for antibacterial drugs. © 2023 Society of Chemical Industry.
Keywords: Xanthomonas oryzae; aldehydes; amines; antibacterial activity; mechanism of action.
© 2023 Society of Chemical Industry.