Effects of the novel mitochondrial targeted compound phosundoxin against <i>Sporothrix globosa</i> : Microbial sensitivity test combined with transcriptomics and proteomics

In recent years, the resistance of Sporothrix globosa to antifungal treatments has steadily increased, while the cure rate for sporotrichosis has declined. This growing resistance underscores the urgent need to develop novel antifungal agents with distinct mechanisms of action. Previous studies have demonstrated that phosundoxin, a biphenyl aliphatic amide that targets mitochondria, exhibits potent inhibitory effects against a broad spectrum of fungi. To further evaluate its antifungal activity, we conducted drug susceptibility testing on 112 S. globosa strains and compared the results with those of conventional antifungal agents. Phosundoxin consistently exhibited antifungal activity against all tested strains, including both mycelial forms and 32 yeast-phase strains, at concentrations ranging from 1 to 4 µg/ml. Notably, in itraconazole-resistant S. globosa strains, phosundoxin treatment led to the identification of 553 differentially expressed genes and 273 differentially expressed proteins. Integrated Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses revealed that phosundoxin exerts its antifungal effects by disrupting the mitochondrial respiratory chain and oxidative phosphorylation. This disruption triggers cellular stress responses, including the upregulation of ammonia transport and nitrogen metabolism. Additionally, phosundoxin treatment weakens cellular defense mechanisms, interferes with the cell cycle, and inhibits protein synthesis-ultimately leading to negative regulatory effects and cell death. These findings highlight phosundoxin's potential as a novel antifungal agent for treating S. globosa infections and provide critical insights into its mechanism of action against this pathogen.