Notoginsenoside R1 as a Protector Against Gentamicin Ototoxicity: Targeting p62-NRF2-GPX4 Ferroptosis Axis

Sudden sensorineural hearing loss (SSNHL) is a common auditory disorder, with oxidative stress and ferroptosis implicated in its pathogenesis. Notoginsenoside R1, a major component of Panax notoginseng, exhibits antioxidant and cytoprotective effects, but its role in ferroptosis regulation remains unclear. In this study, a mouse model of SSNHL and an oxygen-glucose deprivation/reoxygenation (OGD/R)-induced Ear Institute-Organ of Corti 1 (HEI-OC1) cell model were used to evaluate the effects of Notoginsenoside R1. Notoginsenoside R1 significantly reduced auditory brainstem response (ABR) thresholds, reduced cochlear hair cell apoptosis, and alleviated oxidative damage. It inhibited ferroptosis by decreasing Fe^{2 +}, ROS, MDA, and LPO levels, while upregulating SOD, GSH, GCL, and GPX4. Mechanistically, nuclear factor erythroid 2-related factor 2 (NRF2) was identified as a key responsive target through target prediction and qPCR validation, while molecular docking and microscale thermophoresis (MST) assays demonstrated a direct interaction between Notoginsenoside R1 and SQSTM1 (p62). Besides, Notoginsenoside R1 enhanced p62 expression and promoted NRF2 nuclear translocation, restoring expression of GCLC, GCLM, and GPX4. Both p62 knockout and siRNA-mediated knockdown progressively attenuated these protective effects. These findings suggest that Notoginsenoside R1 protects against SSNHL by inhibiting ferroptosis and oxidative stress via activation of the p62-NRF2-GCL-GPX4 axis.