Isolation and structural characterization of antioxidant peptides from horse bone marrow protein hydrolysates

This study aimed to investigate the structural features and antioxidant activity in vitro of horse bone marrow protein (HBMP) hydrolysate based on the activity-originated approach. Antioxidant peptides were isolated from the HBMP with different enzymes. Then, the structural features of the obtained peptide were characterized by extensive chemical, spectroscopic, and chromatographic methods. Antioxidative properties were evaluated through the determination of free radicals scavenging activity. The results showed that alcalase was determined to be the most effective for the generation of antioxidant peptides, and the highest degree of hydrolysis (39.89%) and free radical scavenging activity (55.73%) were obtained under the condition of enzyme concentration 0.9%, pH 9.5, temperature 50℃, solid-liquid ratio 1:16 g/mL through optimized by response surface methodology. HBMP and its hydrolysates were rich in beneficial amino acids. Fourier transforms infrared spectroscopy (FT-IR) and Circular dichroism (CD) revealed key functional structures of obtained peptides whereas Scanning electron microscope-energy dispersive X-ray (SEM-EDX) exhibited its characteristic morphology and elemental composition. The molecular weight distribution of the HBMP alcalase hydrolysate was 2189.014-11561.368 Da determined by Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS) analysis. The antioxidant activity test showed that enzymatic hydrolysis can significantly enhance the activity of the HBMP (P < 0.05). The results indicated that HBMP exhibited significant antioxidant activity in vitro, supporting the potential application of HBMP as antioxidants in food processing, pharmaceuticals, and other industries.