Hesperetin Attenuates Experimentally Induced Skeletal Muscle Dysfunction by Modulating Time-of-Day-Dependent Gene Expression and Mitochondrial Redox-Related Markers.

Skeletal muscle aging is characterized by impaired myogenic differentiation, mitochondrial dysfunction, oxidative stress, and circadian rhythm disruption, contributing to sarcopenia and muscle atrophy. Hesperetin, a natural flavonoid, has antioxidant and mitochondrial protective effects; however, its role in skeletal muscle circadian regulation during aging remains unclear. This study investigated the effects of hesperetin (20 µM or 100 mg/kg b.w.) using D-galactose (D-gal, 20 g/L)-induced senescent C2C12 myotubes, a D-gal (150 mg/kg b.w., i.p.)-induced aging mouse model, and a dexamethasone (Dex, 20 mg/kg b.w., i.p.)-induced muscle atrophy model. In D-gal-treated mice, hesperetin improved hanging test performance and increased SDH-positive area, particularly during the active phase. Hesperetin also partially modulated core clock gene expression and mitochondrial function-related gene expression. In D-gal-induced senescent C2C12 myotubes, hesperetin improved myotube formation, reduced SA-β-gal-positive cells, DCF-DA fluorescence, and MDA levels, enhanced antioxidant enzyme activities, and improved mitochondrial-associated functional indicators, including ATP levels, mitochondrial membrane potential-related fluorescence, pMitoTimer-based mitochondrial oxidation-associated signals, and Ppargc1a expression patterns. These findings suggest that hesperetin may protect against experimentally induced skeletal muscle dysfunction by modulating time-dependent gene expression, mitochondrial-related activities, and muscle-related functional markers.