In vitro response of human ovarian cancer cells to dietary bioflavonoid isoquercitrin

Isoquercitrin is a dietary bioflavonoid used as a food supplement. We studied the mechanism underlying its effect in human ovarian cancer cells using OVCAR-3 cell line. Viability, survival, apoptosis, release of human transforming growth factor-beta 1 (TGF-beta 1) and TGF-beta 1 receptor, and intracellular reactive oxygen species (ROS) generation by OVCAR-3 cells were examined after isoquercitrin treatment at concentrations 5, 10, 25, 50, and 100 mu g mL(-1). AlamarBlue assay revealed that isoquercitrin did not cause any significant change (P > 0.05) in cell viability as compared to control. Apoptotic assay using flow cytometry did not find any significant change (P > 0.05) in the proportion of live, dead and apoptotic cells as compared to control. ELISA also showed that the release of human TGF-beta 1 and TGF-beta 1 receptor were not significantly (P > 0.05) affected by isoquercitrin as compared to control. Chemiluminescence assay demonstrated that lower concentrations (5, 10, and 25 mu g mL(-1)) were able to exhibit beneficial effects by inhibiting the generation of intracellular ROS. In contrast, elevated concentrations of 50 and 100 mu g mL(-1) led to oxidative stress (P < 0.05). We concluded that the beneficial effect of isoquercitrin on ovarian cancer cells may be mediated by an antioxidative pathway that involves inhibition of intracellular ROS generation, thereby limiting oxidative stress.