Studies On The Isolation, Purification And Activities Of Functional Peptides From Pig Placenta

The placental peptide is one of the important resources for functional food development.Although pig placenta contains a variety of amino acids, which are essential for human, such as valine,leucine, lysine, etc, and it also has many other biological functions, such as endocrine, blood,immunity, memory regulation and annti-stress, it is still not well utilization. It has an importanttheoretical and practical significance to explore its biological activity and developing specialbiological activity such as antioxidant, blood pressure lowering to product the functional foods andbiological products. In this paper, the preparation of the pig placenta antioxidant peptides using theenzymatic hydrolysis method was investigated. The digested effect of five proteases, Pepsin, Papain,Flavourzyme, Protamex and Flavor Protamex was compared firstly and we found that pepsin was thebest protease for pig placenta hydrolysis. Significance to study the pig placenta biological activity isto provide the basis for the full use of the pig placenta. The main conclusions are listed as following:1. One-factor-at-a-time and orthogonal array design methods were employed to investigate theeffects of enzyme to substrate ratio, temperature and pH value on the reducing power of the peptides.The hydrolysate with optimal reducing power was predicted to be obtained at: enzyme to substrateratio of13%, temperature of30, and pH value of2.5. Under the optimum conditions, the test resultsdisplayed that the reducing power of1.3257, the degree of hydrolysis of41.38%.2. The highest absorbance peak of the pig placenta was205nm by ultraviolet scanning; thepeptide content of the pig placenta was17.37mg/mL by ultraviolet absorbance assay.3. The correctness of the different molecular weight hydrolysates were verified by SDS-PAGE.The antioxidant activities of the different molecular weight of the pig placenta hydrolysates weredetermined by the DPPH radical scavenging assay and we found that the <3KD pig placentahydrolysates showed the best activity. The <3KD pig placenta hydrolysates fraction was furtherpurified with gel filtration chromatography G-25and G-10column and a higher activity of fraction Bwas obtained. Its IC50values of DPPH radical scavenging activity and ACE inhibitory activity were7.89mg/mL and12.69mg/mL respectively.4. The stability of pig placenta hydrolysates to temperature and acid-base treatment wasinvestigated by using DPPH radical scavenging activity as a key indicator. The pig placenta hydrolysates DPPH radical scavenging activity of IC50values was9.89mg/mL,9.5mg/mL,8.94mg/mL,9.63mg/mL after high temperature, low temperature, acid, base treatment. Comparing IC50value of untreated hydrolysates was7.89mg/mL. This result indicate that the pig placentahydrolysates were relatively stable.