Purpose: The resistance of C. albicans  to traditional antifungal drugs brings a great challenge to clinical treatment. To overcome the resistance, developing antifungal agent sensitizers has attracted considerable attention. This study aimed to determine the anti-Candida  activity of BEH alone or BEH–FLC combination and to explore the underlying mechanisms.
Materials and Methods: In vitro antifungal effects were performed by broth microdilution assay and XTT reduction assay. Infected Galleria mellonella  larvae model was used to determine the antifungal effects in vivo. Probes Fluo-3/AM, FITC-VAD-FMK and rhodamine 6G were used to study the influence of BEH and FLC on intracellular calcium concentration, metacaspase activity and drug efflux of C. albicans .
Results: BEH alone exhibited obvious antifungal activities against C. albicans . BEH plus FLC not only showed synergistic effects against planktonic cells and preformed biofilms within 8 h but also enhanced the antifungal activity in infected G. mellonella  larvae. Mechanistic studies indicated that antifungal effects of drugs might be associated with the increasement of calcium concentration, activation of metacaspase activity to reduce virulence and anti-biofilms, but were not related to drug efflux.
Conclusion: BEH alone or combined with FLC displayed potent antifungal activity both in vitro and in vivo, and the underlying mechanisms were related to reduced virulence factors.
Keywords: fluconazole-resistant Candida albicans , benserazide, fluconazole, synergism, biofilm, Galleria mellonella