The antifungal and antibiofilm effects of isobavachalcone on Candida glabrata (Nakaseomyces glabratus) are associated with intracellular ROS production and cell membrane damages.

Millions of fungal infections are reported every year, while the current antifungal drugs are so few that the clinical choices are limited. The opportunistic fungal pathogen Candida glabrata (reclassified as Nakaseomyces glabratus) caused more infections than any other Candida species except C. albicans. This research sought to explore the antifungal effects of isobavachalcone (IBC, a bioactive chalcone from Psoralea corylifolia) on C. glabrata planktonic growth and biofilms. Our results showed that IBC has potent antifungal activity against C. glabrata (MIC: 4-5 μg/mL), including both the standard strain and clinical isolates. This compound could also inhibit C. glabrata biofilm formation and development. Its antifungal mechanism involves intracellular ROS overproduction and cell membrane impairments, which were revealed by confocal laser scanning microscope observation after fluorescent staining of ROS and plasma membrane. N-acetyl-cysteine rescue tests also confirmed that the ROS-inducing activity of IBC contributed to its antifungal and antibiofilm effects on C. glabrata. Micrographs obtained with electron microscope revealed as well the impairments to C. glabrata plasma membrane caused by IBC. In conclusion, our results obtained here indicated that IBC is a promising antifungal candidate for treating C. glabrata infections.