Carnosol inhibits KGN cells oxidative stress and apoptosis and attenuates polycystic ovary syndrome phenotypes in mice through Keap1-mediated Nrf2/HO-1 activation

Excessive oxidative stress and apoptosis of ovarian granulosa cells lead to abnormal follicular development and ovulation disorders in polycystic ovary syndrome (PCOS). Carnosol is a plant-derived polyphenol that has been proven to exhibit several cell protective effects. In this study, we established hyperandrogenic PCOS models both in vitro and in vivo. In the human ovarian granulosa cell line, KGN cells, decreased viability and mitochondrial membrane potential, and upregulated reactive oxygen species (ROS) level and apoptosis induced by DHT were partly reversed by carnosol. Western blotting results showed that carnosol treatment inhibited the DHT-activated mitochondrial apoptotic pathway by activating nuclear factor-erythroid 2-related factor (Nrf2)/heme oxygenase 1 (HO-1). Knockdown of Nrf2 by transfecting with siRNA or inhibiting HO-1 by zinc protoporphyrin (ZnPP) blocked the protective effects of carnosol. Computational modeling and pull-down assay results confirmed the direct binding of carnosol to kelch-like ECH-associated protein 1 (Keap1). In vivo results showed that the intraperitoneal administration of carnosol (50 and 100 mg/kg) improved estrous cycle disorders, polycystic ovary, and decreased elevated androgen in the PCOS mice. In summary, Carnosol has an effective role in inhibiting oxidative stress and apoptosis in DHT-treated KGN cells and protecting against mouse PCOS phenotypes through the Keap1-mediated activation of Nrf2/HO-1 signaling.