Design, synthesis, antibacterial activity, and mechanism study of phosphate-containing vanillin sulfonylhydrazide...

The increasing prevalence of phytopathogenic bacteria, such as Xanthomonas oryzae pv. oryzicola (Xoc), Xanthomonas axonopodis pv. citri (Xac) and Pseudomonas syringae pv. actinidiae (Psa), poses a serious threat to global agricultural productivity, underscoring the urgent need for novel antibacterial agents with distinct mechanisms of action. This study designed, synthesized, and evaluated a series of phosphonyl-substituted vanillyl sulfonyl hydrazide derivatives for their antibacterial activity and to elucidate the potential mechanisms of action of the most active compound.

In total, 26 novel phosphonyl-substituted vanillyl sulfonyl hydrazide derivatives C were synthesized and structurally confirmed. Bioassays revealed that most compounds exhibited moderate to good antibacterial activity against the tested pathogens. Notably, compound C02 exhibited the most potent activity against Xoc, with a half-maximal effective concentration (EC₅₀) value of 28.2 mg/L. Mechanistic studies revealed that C02 binds to the active cavity of the target protein (Protein Data Bank code: 4Z8V), forming stable interactions. Further analysis showed that C02 is highly chemically reactive and stable, disrupts bacterial cell membrane integrity (causing wrinkling and rupture), and considerably inhibits the activity of the key metabolic enzymes. Proteomic analysis demonstrated that C02 treatment broadly disrupts bacterial metabolic pathways, including energy metabolism, amino acid synthesis, and cell membrane biosynthesis.

Compound C02 exerts its potent antibacterial effects through a multi-mechanism action involving membrane disruption and interference with multiple core metabolic processes. These findings provide a theoretical foundation and experimental evidence for developing novel antibacterial agents based on the phosphate-containing vanillin sulfonyl hydrazide scaffold, significantly advancing the field by identifying a promising lead compound with a well-characterized, multi-faceted mode of action. © 2026 Society of Chemical Industry.