Structural Characterization, Functional Properties and Antioxidant Activity Analysis of Polyphenols and Sea Cucumber Ovum Peptide Complexes

Objective: The complexes of polyphenol and sea cucumber ovum polypeptide (SCOP) were prepared and their structure and function were studied. Methods: Chlorogenic acid (CA) and epigallocatechin gallate (EGCG) were non-covalently combined with SCOP to prepare polyphenol-SCOP complex. The structural changes of polyphenol-SCOP complex were investigated by multispectral method, and the composite was characterized by particle size, potential and other indicators. Results: The analysis of particle size and zeta potential showed that the average particle size of CA-SCOP complex increased, the average particle size of EGCG-SCOP complex decreased, and the absolute zeta potential value of both compounds increased after adding polyphenols. Significant fluorescence quenching of SCOP was observed upon treatment with both polyphenolic compounds, as evidenced by fluorescence spectroscopy. Ultraviolet-visible absorption spectroscopy (UV-Vis) showed that polyphenols and SCOP interacted and formed new complexes, which changed the microenvironment of the aromatic residues in the spatial structure of the polypeptide and induced the conformational change of SCOP. The results of infrared spectrum analysis showed that the absorption peak of the amide Ⅰ band was enhanced, which confirmed that the introduction of polyphenols changed the secondary structure of SCOP. In addition, the antioxidant activity and water and oil holding capacity of the polyphenol SCOP complex increased with the increase of polyphenol concentration. Conclusion: The structural and functional properties of two polyphenols and SCOP non-covalent complexes were studied. In summary, the addition of polyphenols changed the conformation of SCOP and improved its functional properties. This study provides a new theoretical basis for the functional application of SCOP, which is conducive to the development of high value-added Marine bioactive products and the efficient utilization of sea cucumber resources.