Sodium New Houttuyfonate InhibitsCandida albicansBiofilm Formation by Inhibiting the Ras1-cAMP-Efg1 Pathway Revealed by RNA-seq

Here, we aim to investigate the antifungal effect and mechanism of action of sodium new houttuyfonate (SNH) againstCandida albicans. Microdilution analysis results showed that SNH possesses potent inhibitory activity againstC. albicansSC5314, with a MIC(80)of 256 mu g/mL. Furthermore, we found that SNH can effectively inhibit the initial adhesion ofC. albicans. Inverted microscopy, crystal violet staining, scanning electron microscopy and confocal laser scanning microscopy results showed that morphological changes during the transition from yeast to hypha and the biofilm formation ofC. albicansare repressed by SNH treatment. We also found that SNH can effectively inhibit the biofilm formation of clinicalC. albicansstrains (Z103, Z3044, Z1402, and Z1407) and SNH in combination with fluconazole, berberine chloride, caspofungin and itraconazole antifungal agents can synergistically inhibit the biofilm formation ofC. albicans. Eukaryotic transcriptome sequencing and qRT-PCR results showed that SNH treatment resulted in significantly down-regulated expression in several biofilm formation related genes in the Ras1-cAMP-Efg1 pathway (ALS1, ALA1, ALS3, EAP1, RAS1, EFG1, HWP1, andTEC1) and significantly up-regulated expression in yeast form-associated genes (YWP1andRHD1). We also found that SNH can effectively reduce the production of key messenger cAMP in the Ras1-cAMP-Efg1 pathway. Furthermore, usingGalleria mellonellaas anin vivomodel we found that SNH can effectively treatC. albicans infectionin vivo. Our presented results suggest that SNH exhibits potential antibiofilm effects related to inhibiting the Ras1-cAMP-Efg1 pathway in the biofilm formation ofC. albicans.