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-ß1 (TGF-ß1) and TGF-ß1 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 µg 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-ß1 and TGF-ß1 receptor were not significantly (P > 0.05) affected by isoquercitrin as compared to control. Chemiluminescence assay demonstrated that lower concentrations (5, 10, and 25 µg mL-1) were able to exhibit beneficial effects by inhibiting the generation of intracellular ROS. In contrast, elevated concentrations of 50 and 100 µg 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.

Dietary bioflavonoid quercetin modulates porcine ovarian granulosa cell functions in vitro.

Quercetin is a dietary bioflavonoid used widely as a food supplement and is generally recognized as safe. The aim of this in vitro study was to examine the steroid hormone (progesterone and 17- ß estradiol) release, proliferation (PCNA and cyclin B1) and apoptosis (caspase 3 and p53) of porcine ovarian granulosa cells after the addition of quercetin at concentrations 0.01, 0.1, 1, 10 and 100 µmol L-1. Progesterone release was stimulated at the concentration 10 µmol L-1. Quercetin neither had any impact on 17-ß estradiol secretion nor on the presence of PCNA. However, a significant enhancement of the occurrence of cyclin B1 was noted except for the lowest concentration 0.01 µmol L-1. Quercetin did not have any influence on the number of granulosa cells containing caspase 3, but at the concentration 10 µmol L-1 it inhibited p53 occurrence. Results confirm the safety of quercetin in porcine ovarian granulosa cell model and further suggest its possible concentration-dependent influence on ovarian functions through pathway that may involve progesterone, cyclin B1 and p53.

Green tea extract affects porcine ovarian cell apoptosis.

Green tea is a commonly used beverage and green tea extract is a common dietary herbal supplement manufactured into different over-the-counter products. The aim of this in vitro study was to examine the steroid hormone secretion (progesterone and 17-ß estradiol), proliferation and apoptosis of porcine ovarian granulosa cells after addition of green tea extract. Granulosa cells were incubated with green tea extract at five doses (0.1, 1, 10, 100 and 200 µg/ml) and the release of hormones by granulosa cells was assessed by EIA after 24 h exposure. The presence of proliferation and apoptotic markers was assessed by immunocytochemistry. Secretion of steroid hormones was not affected by green tea extract at all the doses in comparison to control. Also, markers of proliferation (PCNA and cyclin B1) were not affected by green tea extract. However, the highest dose (200 µg/ml) of green tea extract used in this study increased the accumulation of apoptotic markers caspase-3 and p53 in granulosa cells. In conclusion, our results indicate the impact of green tea extract at the highest dose used in this study on ovarian apoptosis through pathway that includes activation of caspase-3 and p53. Potential stimulation of these intracellular regulators could induce the process of apoptosis in ovarian cells.