Repurposing Marine Waste into Functional Antioxidants: Boiled Tuna Skin Enzyme Hydrolysate Mitigates AAPH-Induced Oxidative Stress and Apoptotic DNA Damage Across In Vitro and In Vivo Models

The seafood processing industry generates significant amounts of solid waste, including boiled tuna skin, a major byproduct with limited commercial use. Antioxidant activities of Flavourzyme hydrolysate derived from boiled Skipjack tuna (Katsuwonus pelamis) skin byproduct were assessed for their ability to reduce AAPH-induced oxidative stress in In Vitro and In Vivo. The functional properties were improved by enzymatic hydrolysis with Flavourzyme at pH 7.0 to produce an antioxidant hydrolysate. Antioxidant activity was evaluated for boiled tuna skin Flavourzyme hydrolysate (BTSFH) using Hydrogen Peroxide Scavenging activity and ABTS radical scavenging activity. The IC50 values for H2O2 and ABTS radical-scavenging activities were 2.91 mg/mL and 7.52 mg/mL. BTSFH treatment increased cell viability, significantly reduced ROS production under AAPH-induced oxidative stress, and protected against AAPH-induced apoptotic DNA damage. BTSFH exhibited potent antioxidant activity by upregulating endogenous antioxidant enzymes (SOD and Catalase) in AAPH- stimulated Vero cells. An in vivo zebrafish assay demonstrated its antioxidant potential effects by reducing ROS generation, lipid peroxidation, and cell death, thereby supporting its potential as a bioactive compound. These in vitro and in vivo studies’ findings showed that the BTSFH sample represented strong antioxidant activity, making it preliminary evidence for use in pharmaceuticals and health supplements. Marine byproducts as a source of functional ingredients help reduce waste and promote better resource management, aligning with broader goals for a more sustainable circular bioeconomy.