Antioxidant Activity and Effects of Protamex-Assisted Protein Hydrolysates from Trichiurus lepturus By-Products in a Dexamethasone-Induced C2C12 Muscle Atrophy Model

Hairtail (Trichiurus lepturus) is a popular fish species in South Korea that generates substantial quantities of processing byproducts. This study investigated the potential functional properties of hairtail byproducts to enhance their utilization. Proximate composition analysis showed that crude protein was the most abundant component, accounting for approximately half of the total composition. Therefore, protein hydrolysates were prepared from hairtail byproducts using Protamex-assisted enzymatic hydrolysis. The yield of Protamex-assisted enzymatic hydrolysate (HBP) produced based on the raw material drying weight was 42.8%. Amino acid analysis revealed high levels of Aspartic acid and glutamic acid, which can provide instrumental help in muscle synthesis and growth, and free amino acids showed high L-leucine content. HBP also exhibited considerable antioxidant activity. In a dexamethasone-induced C2C12 cell atrophy model, HBP increased cell viability in a concentration-dependent manner, reaching 120.58% at 300 µg/mL. Cell proliferation also increased in a concentration-dependent manner, reaching 125.54% at the same concentration. Immunofluorescence analysis of myosin heavy chain (MyHC) and DAPI staining further indicated concentration-dependent enhancement of muscle cell differentiation. These findings suggest that hairtail byproducts may provide a sustainable source of functional protein hydrolysates with potential protective effects against muscle atrophy in a dexamethasone-induced C2C12 model.