Design, Synthesis, and Study of Prenylated Carbazole Derivatives as Potential Antimicrobial Agents

Crop diseases caused by agricultural pathogens are a constant threat to food security. New antimicrobial agents are urgently required to address the toxicity and resistance issues of existing commercial agents. Inspired by the active fragments of natural prenylated carbazole alkaloids, this study synthesized a series of prenylated carbazole derivatives using a skeleton hybridization and fragment splicing strategy. Compounds C1-4, C1-15, and C1-16 demonstrated broad-spectrum in vitro antimicrobial effects which were superior to commercial drugs thiodiazole copper and bismerthiazol. In particular, compound C1-15 had a MIC of 1.56 μg/mL against Xoo, showed promising protective and curative effects in rice plants, with rates of 34.1% and 42.1%, respectively, and could inhibit bacterial growth, reduce expression of virulence factors, disrupt bacterial cellular metabolism, and even induce bacterial death. In addition, these compounds provided favorable inhibitory effects against foodborne bacteria. The above results indicated the value of prenylated carbazole derivatives as potential antimicrobial agents.