Preparation and Hypoglycemic Activity of Enzymatically Hydrolyzed Peptides From the Swim Bladder of Pangasius bocourti.

The swim bladder of Pangasius bocourti is an underutilized fishery byproduct with high protein content, yet its potential as a source of hypoglycemic peptides has not been systematically investigated. This study aimed to prepare and characterize bioactive peptides from P. bocourti swim bladder (PBSB) through integrated enzymatic hydrolysis optimization, peptidomic analysis, and in vivo evaluation. Five proteases were comparatively assessed, and alkaline protease was identified as the optimal enzyme based on degree of hydrolysis and α-glucosidase inhibitory activity. Under the optimized conditions (pH 9.5, enzyme dosage 2%, 50°C, 4 h), the obtained peptides (PBSBPs) exhibited notable α-glucosidase inhibitory activity (67.90% ± 0.26% at 5 mg/mL). Nano-LC-MS/MS analysis identified 101 peptides, of which 91.09% had molecular weights below 1500 Da. The peptide sequences were enriched in hydrophobic and hypoglycemia-associated amino acid residues, and 58 peptides were predicted to possess α-glucosidase inhibitory potential. Furthermore, PBSBPs significantly improved glucose tolerance, reduced serum triglyceride and total cholesterol levels, and alleviated hepatic lipid accumulation and pancreatic islet injury in diabetic mice. This study integrates process optimization, peptide profiling, and biological validation, providing a systematic strategy for the development of functional peptides from aquatic byproducts. These findings highlight the potential application of PBSBPs as natural antidiabetic functional ingredients and contribute to the high-value utilization of fishery processing byproducts.