Chiisanoside Ameliorates d-Galactose-Induced Age-Related Hearing Loss by Modulating Autophagy and Ferroptosis via the SESN2/AMPK Axis.

Age-related hearing loss (ARHL) is a pervasive sensorineural deficit lacking effective pharmacological interventions. Although Eleutherococcus senticosus fruit extracts exhibit otoprotective potential, their precise bioactive constituents and underlying molecular mechanisms remain elusive. Using network pharmacology and transcriptomic analysis as hypothesis-generating tools, followed by experimental validation, this study identifies chiisanoside (CSS) as a key bioactive compound mitigating d-galactose-induced cellular senescence and auditory impairment, with an optimal effective dose of 25 μM in vitro (HEI-OC1 cells) and 50 mg/kg/day in vivo (oral gavage in C57BL/6 mice). Mechanistically, the in vitro and in vivo models demonstrate that CSS suppresses age-related auditory decline primarily by targeting the SESN2/AMPK signaling axis. Specifically, CSS upregulates SESN2 to activate AMPK, which not only enhances autophagy via the mTOR/ULK1 pathway but also concurrently inhibits the HIF-1α/TFRC/FTH1 cascade. These findings provide mechanistic insights supporting the potential of CSS as a therapeutic candidate in ARHL.