1,2,4-Triazolium compounds as anti-oomycete leads against Phytophthora capsici

1,2,4-Triazolium salts are a class of stable heterocyclic salts widely used as in situ carbene precursors in organic synthesis, and they have also been reported to exhibit favorable physicochemical properties and diverse biological activities. This study aims to elucidate the potential of 1,2,4-triazolium salts as antifungal and anti-oomycete agents.

In this study, a series of 1,2,4-triazolium derivatives were evaluated for their inhibitory activities against phytopathogenic oomycete Phytophthora capsici. Compound 42 displayed the most potent in vitro activity against P. capsici, with a half-maximal effective concentration (EC₅₀) of 5.38 μg mL^-1, and demonstrated good protective efficacy in vivo against P. capsici. Scanning electron microscopy (SEM) revealed that treatment of P. capsici with compound 42 at 50 μg mL^-1 caused pronounced morphological abnormalities in the hyphae, characterized by severe collapse and shrinkage. Molecular docking studies revealed favorable binding interactions between compound 42 and uridine phosphorylase (UPase, PDB ID: 6KD3), providing possible mechanistic insights into its inhibitory activity.

Our results establish 1,2,4-triazolium compound 42 as a promising scaffold for the future development of anti-oomycete agents, offering a potential molecular basis for the design of novel crop protectants against P. capsici. © 2026 Society of Chemical Industry.