Antioxidant And Tumor Growth Inhibition Activity Of Peptides Prepared From Silkworm Pupae Protein

Silkworm pupae(Bombyx mori) approved as ordinary food management list new food resources by the Ministry of Health, is the only insect food with high nutritional and medicinal value. The crude protein content of dry silkworm pupae is up to 60-70%, and the protein hydrolysates have extensive activities in antioxidation, antitumor, antibacterial, immunity and other aspect. Take the silkworm pupae as raw material, get bioactive peptide through enzymatic hydrolysis, and study their functional properties to increase the added value of the pupa protein and meet the diverse needs of seasonings market is a very important significance. Alcalase, Neutrase, Protamex, Papain, Flavourzyme, and Trypsin were used as biocatalyst to hydrolyze the silkworm pupae(Bombyx mori) protein(SPP) to prepare antioxidant peptides, and effects on the antioxidant activities of the type of enzyme, the degree of hydrolysis(DH) of hydrolysates were investigated. The results showed that all hydrolysates have certain antioxidant capacity, according to the main component analysis, Neutrase hydrolysates(NH) have the highest total antioxidant capacity. Then we study the antioxidant activity in vitro of different degree of NHs, and found that NH possess the strongest antioxidant capacity at the 15% degree of hydrolysis.As same as the antioxidant peptides, we choose the best hydrolysates–Acalase hydrolysates(AH) against the proliferation of tumor from the six hydrolysates by MTT. Then the different degree of hydrolysis(DH) of AH were prepared, then their antitumor activities were studied. We found that of AH had the highest activity at the 25% degree of hydrolysis.On the basis of the determinate enzyme type and degree of hydrolysis, membrane ultrafiltration was used to separating the 25% degree of hydrolysis of AH to different components(<5k、5-10k、10-30k、>30k) according to their molecular weight. After ultrafiltration,the component of molecular weight less than 5k shows the highest antitumor activity, and through Sephadex G-25 chromatographic column,there came out 4 peaks(a, b, c, d). Although the component b had antitumor activity on MGC-803 cells in some extent, it well be lower than the component of molecular weight less than 5k. Conclusion that: The Enzyme peptide of silkworm papue protein do have antitumor activity, of which the AH shows the highest antitumor activity, and the molecular weight less than 5k worked best, and the four components separated by Sephadex chromatographic column may have the synergy.To sum up, NH has the highest total antioxidant capacity, and the AH shows the highest antitumor activity to MGC-803 in the six kinds of silkworm papue protein hydrolysates(SPPHs). Therefore, functional properties(solubility, emulsification, thermal stability et al.) of different degrees of hydrolysis of NH and AH were studied to detect their application and development prospects in the food, cosmetics, pharmaceutical industry. The functional properties of SPPHs, including solubility, thermal stability and emulsion stability index(ESI), had been greatly improved, however, the emulsifying activity(EAI) had declined. SPPHs process good antioxidant activities, antitumor activities and functional properties, could be used as food or food additives, binders used in various food processing industries. This research would provide a source of bioactive peptides of silkworm pupae protein and theoretical and experimental basis, is also important for further research.