The synthesis of arylmethylene bisindoles catalyzed by nickel perchlorate as potential antifungal agent against Clarireedia homoeocarpa

Arylmethylene bisindole alkaloids are predominantly found in cruciferous plants and as metabolites in marine organisms, exhibiting a diverse range of biological activities. In recent years, these alkaloids have been increasingly explored and utilized for controlling plant pathogenic fungi. However, the synthesis and underlying mechanisms, particularly their effectiveness against plant pathogens such as Clarireedia homoeocarpa, still require further investigation. In this study, a series of arylmethylene bisindoles were synthesized with high yield using aromatic aldehydes and indoles catalyzed by NiClO₄·6H₂O. These compounds showed spectral antibacterial activity against six major phytopathogenic fungi and A13 exhibiting the highest antifungal activity against C. homoeocarpa with an EC₅₀ value of 0.74 mg/L. Furthermore, in vivo antifungal assays were performed to assess the efficacy of the active compounds against C. homoeocarpa. To elucidate the antifungal mechanism of arylmethylene bisindoles, a comprehensive analysis of physiological and biochemical indices, along with transcriptome profiling, was carried out to elucidate. The results demonstrated that A13 treatment can efficiently disrupt the cell membranes of C. homoeocarpa. Additionally, we identified and screened the candidate genes implicated in cell membrane alterations under A13 treatments. KEGG pathway analysis revealed that a considerable number of down-regulated DEGs were significantly enriched in metabolic pathways, biosynthesis of secondary metabolic, and ribosome biogenesis in eukaryotes. This research provides valuable insights for the effective management of lawn coin spot disease.