Sesaminol Inhibits Adipogenesis by Suppressing Mitotic Clonal Expansion and Activating the Nrf2-ARE Pathway

Background: As a key contributor to metabolic disorders, obesity is recognized as a critical global health challenge. Adipocyte differentiation depends on the mitotic clonal expansion (MCE) phase, which is controlled by oxidative balance and transcription factors like C/EBPβ. Sesaminol, a lignan derived from Sesamum indicum, has potent antioxidant properties. This study aimed to investigate whether sesaminol suppresses adipogenesis by modulating ROS signaling, MCE, and the Nrf2-ARE pathway. Methods: In the early period of adipogenic induction, 3T3-L1 preadipocytes received treatment with sesaminol. Adipogenic development was evaluated through Oil Red O staining together with the assay of GPDH activity. Assays of cell proliferation and expression of cell cycle-related proteins, along with ROS measurement, qRT-PCR, Western blotting, and immunofluorescence, were performed to evaluate the effects on oxidative stress, transcriptional regulation, and AMPK-Nrf2 signaling. Results: Sesaminol significantly inhibited lipid accumulation and GPDH activity without cytotoxicity. It suppressed MCE by inhibiting DNA synthesis and reducing the expression of cyclin E1/E2 and CDK2. Sesaminol decreased C/EBPβ expression and its nuclear localization, resulting in lower levels of C/EBPα and PPARγ. It also reduced intracellular ROS, promoted nuclear translocation of Nrf2, and upregulated antioxidant genes HO-1 and GCLC. AMPK phosphorylation was concurrently enhanced. Conclusions: Sesaminol inhibits early adipogenesis by suppressing ROS-mediated MCE and activating the AMPK-Nrf2-ARE signaling pathway, leading to downregulation of key adipogenic transcription factors. The present study supports the potential of sesaminol as an effective strategy for obesity prevention.