Isoquercitrin, isolated from Aster yomena triggers ROS-mediated apoptosis in Candida albicans

Isoquercitrin has received much interest due to its various biological activities and exerts the antifungal effect. Therefore, we aimed to discover the novel antifungal mechanism of isoquercitrin in Candida albicans, showing apoptotic cell death. Using 2', 7'-dichlorodihydrofluorescein diacetate (H2DCFDA) staining, the levels of reactive oxygen species (ROS) were measured and isoquercitrin revealed different effects in a concentration-dependent manner: ROS scavenging effect (low concentration) and ROS forming effect (high concentration). Furthermore, we used the antioxidant, N-acetylcysteine (NAC) to discriminate the influence of ROS in DNA fragmentation and caspase activation. The green fluorescence of TUNEL and FITC-VADFMK was detected in high concentration-treated cells, whereas there was no fluorescence in both low concentration-treated cells and NAC-treated cells. These results demonstrated that ROS generation is the crucial factor in isoquercitrin-induced apoptosis. Thus, isoquercitrin induces ROS-mediated apoptosis in C. albicans.