Valorization of rabbit viscera by enzymatic hydrolysis: bioactive peptides with antioxidant and cell viability properties

Rabbit meat production generates large amounts of viscera (20-25% of live weight), which are an underutilized, protein-rich by-product. This study aimed to evaluate rabbit viscera as a substrate for enzymatic hydrolysis and to assess the antioxidant capacity and effects on cell viability of the resulting hydrolysates. Viscera from commercial crossbred rabbits (California × New Zealand) were defatted, sterilized, and lyophilized. Hydrolysis was performed independently with Alcalase and Flavourzyme (0-8 h). The hydrolysates were characterized for peptide size distribution by RP-HPLC, antioxidant capacity by DPPH and ORAC assays, and effects on SW-480 colon cancer cell viability by MTT assay. All analyses were conducted on three independent hydrolysis batches. Alcalase hydrolysates showed a higher proportion of peptides below 1 kDa and greater ORAC values (peak of 249.50 ± 7.46 µmol TE/g protein at 6 h) than Flavourzyme hydrolysates. Both hydrolysates reduced SW-480 cell viability in a concentration-dependent manner, with Alcalase generally showing stronger effects. The non-hydrolyzed (0 h) Alcalase sample produced the greatest reduction in viability. DPPH results were considered tentative due to precipitate formation. This exploratory in vitro study demonstrates that enzymatic hydrolysis of rabbit viscera produces hydrolysates with antioxidant capacity and the ability to reduce cell viability. Alcalase was more effective than Flavourzyme. These preliminary findings suggest the potential of rabbit viscera as a source of functional ingredients from an underutilized animal by-product. Further research, including peptide identification and in vivo validation, is needed.