Isorhamnetin and Female Reproduction: Effects on Viability, Hormone Secretion, and Growth Factors

Background/Objectives: Isorhamnetin is a naturally occurring flavonoid with reported antioxidant, anti-inflammatory, and anticancer properties. Although its biological activities have been extensively investigated, its effects on ovarian cell physiology remain insufficiently characterized. This study aimed to evaluate the influence of isorhamnetin on the viability, steroid hormone secretion, apoptosis, and growth factor signalling in human ovarian cell lines representing both non-tumour and tumour phenotypes. Methods: Human granulosa (HGL5), granulosa tumour (COV434), and epithelial ovarian carcinoma (OVCAR-3) cell lines were treated with isorhamnetin at concentrations of 5–80 μg/mL for 24 h. Cell viability was determined using the AlamarBlueTM assay. The secretion of progesterone, 17β-estradiol, and the presence of transforming growth factor β2 (TGF-β2), transforming growth factor β receptor 2 (TGFBR2), and apoptosis-inducing factor (AIF) was quantified by enzyme-linked immunosorbent assay (ELISA). Results: Isorhamnetin significantly reduced cell viability in a dose-dependent manner, with tumour cell lines exhibiting greater sensitivity than non-tumour granulosa cells. A significant decrease in viability was observed in OVCAR-3 cells from 10 μg/mL onward, whereas COV434 cells showed significant reductions at concentrations of 20 μg/mL and higher. In contrast, HGL5 cell viability was significantly affected only at the highest concentration (80 μg/mL). No significant changes were detected in the secretion of progesterone, 17β-estradiol, TGF-β2, or TGFBR2 in any of the examined cell lines. A significant reduction in AIF production was observed only in HGL5 cells treated with 80 μg/mL isorhamnetin. Conclusions: Isorhamnetin preferentially decreased the viability of ovarian tumour cells while exerting only limited effects on non-tumour granulosa cells, indicating preferential cytotoxic activity toward malignant ovarian cells. The absence of significant changes in steroid hormone production and TGF-β suggests that its antiproliferative effects involve molecular pathways that were not investigated in the present study. These findings support further investigation of isorhamnetin as a potential natural compound for ovarian cancer prevention or adjunctive therapy.