Biochanin A Suppresses Growth and Biofilm Formation of Fluconazole-Resistant Candida auris

Invasive fungal infections, especially from Candida auris (C. auris), are a serious threat to immunocompromised patients because of multidrug resistance. Therefore, research into novel antifungal agents or adjuvants for pre-existing treatments is necessary. This study examined the therapeutic potential of biochanin A as an antifungal and anti-biofilm agent against fluconazole-resistant C. auris (FRCA). Its efficacy was determined through minimum inhibitory concentration (MIC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration (MBEC) assays. The fungal metabolic activity in biofilms was measured using the XTT reduction assay and the results were visualized by confocal laser scanning microscopy (CLSM). We also evaluated the effect of biochanin A on C. auris adhesion and the expression of resistance and virulence-associated genes. Biochanin A inhibited the growth of several C. auris strains, with MIC₉₀ values ranging from 16 to 64 µg/mL, as well as a dose-dependent reduction in MBIC and MBEC. The XTT assay and CLSM confirmed a significant inhibition of metabolic activity and viability. In addition, biochanin A reduced C. auris adherence to epithelial cells and downregulated the expression of the azole resistance gene ERG11 and the extracellular matrix gene KRE6. The results suggest that biochanin A is an effective alternative for managing fluconazole-resistant C. auris infections.