In Vitro Synergistic Effects of Hinokitiol and Fluconazole Against Candida albicans

Background: Given the escalating resistance of Candida albicans biofilms to conventional antifungal agents, in this research, we evaluated the potential of combination therapy comprising hinokitiol (HNK) and fluconazole (FLZ), as an alternative, for combating biofilm-associated infections. Methods: To assess their synergistic effects, the fractional inhibitory concentration index was calculated. The viability of biofilms and intracellular oxidative stress were quantified by XTT and reactive oxygen species assays. Structural integrity and viability were further investigated by fluorescence and scanning electron microscopy; gene expression levels were measured by real-time fluorescence analysis. Results: Treatment with HNK combined with FLZ led to noticeable disruptions in the biofilm architecture of Candida albicans and resulted in significant modulation of multiple biofilm-associated genes, such as ALS3 and HWP1. The observed increase in oxidative stress, together with a marked decline in biofilm viability, provided strong support for a synergistic effect between the two compounds. Conclusions: The findings in this study revealed a potential synergistic effect between HNK and FLZ, with influences on fungal biofilm architecture and modulation of genetic pathways associated with biofilm development.